U.S. patent application number 10/672527 was filed with the patent office on 2004-07-29 for building control system using integrated mems devices.
Invention is credited to Ahmed, Osman.
Application Number | 20040144849 10/672527 |
Document ID | / |
Family ID | 32736119 |
Filed Date | 2004-07-29 |
United States Patent
Application |
20040144849 |
Kind Code |
A1 |
Ahmed, Osman |
July 29, 2004 |
Building control system using integrated MEMS devices
Abstract
An apparatus for use in a building system includes at least one
microelectromechanical (MEMS) sensor device and a processing
circuit that are integrated onto a single substrate. The at least
one MEMs sensor device is operable to generate a process value. The
processing circuit is operable convert the process value to an
output digital signal configured to be communicated to another
element of a building automation system. The building automation
system includes one or more devices that are operable to generate a
control output based on set point information and process value
information from one or more sensors.
Inventors: |
Ahmed, Osman; (Hawthorn
Woods, IL) |
Correspondence
Address: |
Siemens Corporation
Intellectual Property Department
170 Wood Avenue South
Iselin
NJ
08830
US
|
Family ID: |
32736119 |
Appl. No.: |
10/672527 |
Filed: |
September 26, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10672527 |
Sep 26, 2003 |
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10353110 |
Jan 28, 2003 |
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Current U.S.
Class: |
236/1E ;
62/126 |
Current CPC
Class: |
G05B 15/02 20130101 |
Class at
Publication: |
236/001.00E ;
062/126 |
International
Class: |
F25B 049/00 |
Claims
I claim:
1. An apparatus for use in a building system, the apparatus
comprising: at least one microelectromechanical (MEMs) sensor
device operable to generate a process value; a processing circuit
operable convert the process value to an output digital signal
configured to be communicated to another element of a building
automation system, the building automation system including one or
more devices that are operable to generate a control output based
on set point information and process value information from one or
more sensors; and wherein the at least one MEMs sensor device and
the processing circuit are integrated onto a first substrate.
2. The apparatus of claim 1 wherein the processing circuit includes
a microelectronics A/D converter, the microelectronics A/D
converter operable to receive the process value from the at least
one MEMs sensor device and generate digital sensor signal
therefrom.
3. The apparatus of claim 1 wherein the output digital signal is
representative of the process value.
4. The apparatus of claim 1 wherein the processing circuit is
further operable to generate a control output based on the set
point information and the process value information from the at
least one MEMs sensor device, and wherein the output digital signal
is representative of the control output.
5. The apparatus of claim 1 wherein the at least one MEMs sensor
device includes a plurality of MEMs sensor devices.
6. The apparatus of claim 1 further comprising a battery secured to
the first substrate.
7. The apparatus of claim 1 wherein the first substrate is a
semiconductor substrate.
8. The apparatus of claim 6 wherein the battery further comprises a
lithium ion battery layer.
9. The apparatus of claim 8 further comprising a power management
circuit operably coupled to the lithium ion battery layer.
10. The apparatus of claim 8 further comprising a second substrate,
and wherein the lithium ion battery layer is disposed between the
first substrate and the second substrate.
11. The apparatus of claim 1 further comprising an RF communication
circuit operably coupled to the processing circuit.
12. The apparatus of claim 1 further comprising an EEPROM operably
coupled to the processing circuit.
13. An arrangement for use in a building system, comprising: a
plurality of sensor modules, each sensor module include at least
one microelectromechanical (MEMs) sensor device, each sensor module
operable to obtain at least one value representative of a
measurable quantity in a building; and a plurality of controllers,
each controller operably connected to receive sensor information
representative of at least one value obtained by at least one MEMs
sensor device, each controller configured to generate a control
output based on the sensor information and set point information,
the control output configured to cause an actuator to effect change
to the measurable quantity.
14. The arrangement of claim 13 wherein at least one of the MEMs
sensor devices and at least one controller is formed on single
substrate.
15. The arrangement of claim 13 wherein at least one sensor module
further comprises a plurality of MEMs sensor devices.
16. The arrangement of claim 13 wherein at least one sensor module
further comprises a microelectronics A/D converter, the
microelectronics A/D converter operable to receive the at least
ones value from the at least one MEMs sensor device and generate
digital sensor signal therefrom.
17. A method, comprising: obtaining from a microelectromechanical
(MEMs) sensor device at least one value representative of a
measurable quantity in a building; generating a control output
based on the at least one value and set point information, the
control output configured to cause an actuator to effect change to
the measurable quantity.
18. The method of claim 17, wherein the set point information
includes a desired temperature value for at least a portion of the
building.
19. The method of claim 17, further comprising providing the
control control output to an actuator in a building comfort
system.
20. The method of claim 17, further comprising communicating
information representative of the at least one value to a
controller using wireless communications, the controller operable
to generate the control output.
Description
[0001] This application is a Divisional of U.S. patent application
Ser. No. 10/353,110, filed Jan. 28, 2003.
CROSS REFERENCE TO RELATED APPLICATION
[0002] Cross reference is made to U.S. patent application Ser.
No.10/353,142, filed Jan. 28, 2003, and which is incorporated
herein by reference.
FIELD OF THE INVENTION
[0003] The present invention relates generally to building control
systems, such of the type that control heating, ventilation, air
conditioning, fire safety, lighting, security and other systems of
a building or facility.
BACKGROUND OF THE INVENTION
[0004] Building control systems are employed to regulate and
control various environmental and safety aspects of commercial,
industrial and residential facilities (hereinafter referred to as
"buildings"). In ordinary single-family residences, control systems
tend to be simple and largely unintegrated. However, in large
buildings, building control systems often consist of multiple,
integrated subsystems employing hundreds of elements.
[0005] For example, a heating, ventilation and air-conditioning
("HVAC") building control system interrelates small, local control
loops with larger control loops to coordinate the delivery of heat,
vented air, and chilled air to various locations throughout a large
building. Local control systems may use local room temperature
readings to open or close vents that supply heated or chilled air.
Larger control loops may obtain many temperature readings and/or
air flow readings to control the speed of a ventilation fan, or
control the operation of heating or chilling equipment.
[0006] To facilitate the control over various aspects of a
building, control systems employ sensing devices that measure
various conditions, such as temperature, air flow, or motion. Other
sensors determine the presence of smoke, the presence of dangerous
or noxious chemicals, light and the like. Sensor devices for use in
building control systems can vary widely in function, size and
cost. Many sensors include mechanical, electromechanical and
electronic elements and thus include a significant amount of parts
that must be manufactured and assembled. In many cases, a building
will have sensor devices from multiple manufacturers that provide
different types of output signals.
[0007] Thus, a significant cost of a building control system
relates to the use of sensor devices. Such costs include the
complex and often bulky sensor units as well as the costs
associated with incorporating and converting various types of
sensor signals to a format used by the building control system.
[0008] As a consequence, there is a need for apparatus and method
that can reduce at least some of the drawbacks and costs identified
above. For example, there is a need for a method and/or apparatus
that reduces the costs associated with the sensing devices that are
necessary for sensing conditions within a building control system.
There is a further need for a sensor that reduces the need for
external signal conversion equipment.
SUMMARY OF THE INVENTION
[0009] The present invention addresses one or more of the above
needs, as well as others, by providing a building control system
that incorporates sensor units that include at least one
microelectromechanical ("MEMs") sensor devices. By incorporating
MEMs sensors, the mechanical and/or electromechanical elements of
the sensor may readily be incorporated with electronic elements
such as processing devices. In embodiments of the invention, the
MEMs sensor devices and at least parts of the electronic elements
are integrated onto a single substrate. The use of such sensors can
result in reduced material cost, bulk and energy costs. The
electronic elements may be used to convert raw sensor signals into
sensor value signals understood by other elements of the building
control system, thereby reducing the need for separate
driver/conversion circuitry.
[0010] A first embodiment of the invention is an apparatus for use
in a building system that includes at least one
microelectromechanical (MEMs) sensor device and a processing
circuit that are integrated onto a single substrate. The at least
one MEMs sensor device is operable to generate a process value. The
processing circuit is operable convert the process value to an
output digital signal configured to be communicated to another
element of a building automation system. The building automation
system includes one or more devices that are operable to generate a
control output based on set point information and process value
information from one or more sensors.
[0011] Other embodiments of the apparatus include additional
circuit elements, such as an EEPROM, a A/D converter, and/or an RF
communication circuit.
[0012] Another embodiment of the invention is an arrangement for
use in a building system that includes a plurality of sensor
modules and a plurality of controllers. Each of sensor modules
includes at least one MEMs sensor device. Each sensor module is
operable to obtain at least one value representative of a
measurable quantity in a building. Each controller is operably
connected to receive sensor information representative of at least
one value obtained by at least one MEMs sensor device, each
controller is configured to generate a control output based on the
sensor information and set point information, the control output
configured to cause an actuator to effect change to the measurable
quantity.
[0013] The above described features and advantages, as well as
others, will become more readily apparent to those of ordinary
skill in the art by reference to the following detailed description
and accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 shows a block diagram of an exemplary building
control system in accordance with the present invention;
[0015] FIG. 2 shows a block diagram of an exemplary space control
subsystem of the building control system of FIG. 1;
[0016] FIG. 3 shows a flow diagram of an exemplary set of
operations of a room control processor of the space control
subsystem of FIG. 2;
[0017] FIG. 4 shows a flow diagram of an exemplary set of
operations of a sensor module controller of the space control
subsystem of FIG. 2; and
[0018] FIG. 5 shows a flow diagram of an exemplary set of
operations of an actuator module controller of the space control
subsystem of FIG. 2.
[0019] FIG. 6 shows a block diagram of a space control subsystem of
the building control system of FIG. 1 that includes a plurality of
fume hoods in accordance with the invention;
[0020] FIG. 7a shows a block diagram of a control module of the
space control subsystem of FIG. 6;
[0021] FIG. 7b shows a flow diagram of the operations of the
processing circuit of the control module of FIG. 7a;
[0022] FIG. 8a shows a block diagram of a supply module of the
space control subsystem of FIG. 6;
[0023] FIG. 8b shows a first flow diagram of the operations of the
processing circuit of the supply module of FIG. 8a;
[0024] FIG. 8c shows a second flow diagram of the operations of the
processing circuit of the supply module of FIG. 8a;
[0025] FIG. 9a shows a block diagram of a main exhaust module of
the space control subsystem of FIG. 6;
[0026] FIG. 9b shows a flow diagram of the operations of the
processing circuit of the main exhaust module of FIG. 9a;
[0027] FIG. 10a shows a block diagram of a fume hood sensor module
of the space control subsystem of FIG. 6;
[0028] FIG. 10b shows a flow diagram of the operations of the
processing circuit of the fume hood sensor module of FIG. 10a;
[0029] FIG. 11a shows a block diagram of a fume hood exhaust module
of the space control subsystem of FIG. 6;
[0030] FIG. 11b shows a flow diagram of the operations of the
processing circuit of the fume hood exhaust module of FIG. 11a;
[0031] FIG. 12a shows a representative side view of a control
system module according to an aspect of the invention; and
[0032] FIG. 12b shows a representative block diagram of the control
system module of FIG. 12a.
DETAILED DESCRIPTION
[0033] FIG. 1 shows a block diagram of an exemplary building
control system in accordance with the present invention. The
building control system 100 includes a supervisory computer 102, a
wireless area network server 104, a chiller controller subsystem
106, a fan controller subsystem 108, and room controller subsystems
110, 112 and 114. The building control system 100 includes only the
few above-mentioned elements for clarity of exposition of the
principles of the invention. Typical building control systems will
include many more space control subsystems, as well as many more
chiller, fan, heater, and other building HVAC subsystems. Those of
ordinary skill in the art may readily incorporate the methods and
features of the invention described herein into building control
systems of larger scale.
[0034] In general, the building control system 100 employs a first
wireless communication scheme to effect communications between the
supervisory computer 102, the chiller controller subsystem 106, the
fan controller subsystem 108, and the room controller subsystems
110, 112 and 114. A wireless communication scheme identifies the
specific protocols and RF frequency plan employed in wireless
communications between sets of wireless devices. In the embodiment
described herein, the first wireless communication scheme is
implemented as a wireless area network. To this end, a wireless
area network server 104 coupled to the supervisory computer 102
employs a packet-hopping wireless protocol to effect communication
by and among the various subsystems of the building control system
100. U.S. Pat. No. 5,737,318, which is incorporated herein by
reference, describes a wireless packet hopping network that is
suitable for HVAC/building control systems of substantial size.
[0035] In general, the chiller controller subsystem 106 is a
subsystem that is operable to control the operation of a chiller
plant, not shown, within the building. Chiller plants, as is known
in art, are systems that are capable of chilling air that may then
be ventilated throughout all or part of the building to enable air
conditioning. Various operations of chiller plants depend upon a
number of input values, as is known in the art. Some of the input
values may be generated within the chiller controller subsystem
106, and other input values are externally generated. For example,
operation of the chiller plant may be adjusted based on various air
flow and/or temperature values generated throughout the building.
The operation of the chiller plant may also be affected by set
point values generated by the supervisory computer 102. The
externally-generated values are communicated to the chiller
controller subsystem 106 using the wireless area network.
[0036] The fan controller subsystem 108 is a subsystem that is
operable to control the operation of a ventilation fan, not shown,
within the building. A ventilation fan, as is known in art, is a
prime mover of air flow throughout the ventilation system of the
building. This primary air flow power may be used to refresh the
air within the facility, and may be used to distribute chilled air
from the chiller plant. As with the chiller plant, ventilation fans
and their implementation within building control systems are well
known in the art. Also, the fan controller subsystem 108 is
similarly configured to receive input values from other subsystems
(or the supervisory computer 102) over the wireless area
network.
[0037] The room controllers 110, 112 and 114 are local controller
subsystems that operate to control an environmental aspect of a
location or "space" within the building. While such locations may
be referred to herein as "rooms" for convenience, it will be
appreciated that such locations may further be defined zones within
larger open or semi-open spaces of a building. The environmental
aspect(s) that are controllable by the space control subsystems
110, 112 and 114 typically include temperature, and may include air
quality, lighting and other building system processes.
[0038] In accordance with one aspect of the present invention, each
of the space control subsystems 110, 112 and 114 has multiple
elements that communicate with each other using a second wireless
communication scheme. In general, it is preferable that the second
communication scheme employ a short-range or local RF communication
sheme such as Bluetooth. FIG. 2, discussed further below, shows a
schematic block diagram of an exemplary room control system that
may be used as the space control subsystems 110.
[0039] Referring to FIG. 2, the space control subsystem 110
includes a hub module 202, first and second sensor modules 204 and
206, respectively, and an actuator module 208. It will be
appreciated that a particular room controller subsystem 200 may
contain more or less sensor modules or actuator modules. In the
exemplary embodiment described herein, the space control subsystem
110 is operable to assist in regulating the temperature within a
room or space pursuant to a set point value. The space control
subsystem 110 is further operable to obtain data regarding the
general environment of the room for use, display or recording by a
remote device, not shown in FIG. 2, of the building control system.
(E.g., supervisory computer 102 of FIG. 1).
[0040] The first sensor module 204 represents a temperature sensor
module and is preferably embodied as a wireless integrated network
sensor that incorporates microelectromechanical system technology
("MEMS"). By way of example, in the exemplary embodiment described
herein, the first sensor module 204 includes a MEMS local RF
communication circuit 210, a microcontroller 212, a programmable
non-volative memory 214, a signal processing circuit 216, and one
or more MEMS sensor devices 218. The first sensor module 204 also
contains a power supply/source 220. In the preferred embodiment
described herein, the power supply/source 220 is a battery, for
example, a coin cell battery.
[0041] Examples of MEMS circuits suitable for implementing the
first sensor module 204 are described in the ESSCIRC98 Presentation
"Wireless Integrated Network Sensors (WINS)", which is published
on-line at www.janet.ucla.edu/WINS/archives, (hereinafter referred
to as the "WINS Presentation"), and which is incorporated herein by
reference.
[0042] The MEMS sensor device(s) 218 include at least one MEMS
sensor, which may suitably be a temperature sensor, flow sensor,
pressure sensor, and/or gas-specific sensor. MEMS devices capable
of obtaining temperature, flow, pressure and gas content readings
have been developed and are known in the art. In a preferred
embodiment, several sensors are incorporated into a single device
as a sensor suite 218. Upon installation, the sensor module 204 may
be programmed to enable the particular sensing capability. By
incorporating different, selectable sensor capabilities, a single
sensor module design may be manufactured for use in a large
majority of HVAC sensing applications. In the embodiment of FIG. 2,
the sensor module 204 is configured to enable its temperature
sensing function.
[0043] The signal processing circuit 216 includes the circuitry
that interfaces with the sensor, converts analog sensor signals to
digital signals, and provides the digital signals to the
microcontroller 212. Examples of low power, micro-electronic A/D
converters and sensor interface circuitry are shown in the WINS
Presentation.
[0044] The programmable non-volatile memory 214, which may be
embodied as a flash programmable EEPROM, stores configuration
information for the sensor module 204. By way of example,
programmable non-volatile memory 214 preferably includes system
identification information, which is used to associate the
information generated by the sensor module 204 with its physical
and/or logical location in the building control system. For
example, the programmable non-volatile memory 214 may contain an
"address" or "ID" of the sensor module 204 that is appended to any
communications generated by the sensor module 110.
[0045] The memory 214 further includes set-up configuration
information related to the type of sensor being used. For example,
if the sensor device(s) 218 are implemented as a suite of sensor
devices, the memory 214 includes the information that identifies
which sensor functionality to enable. (See FIGS. 3 and 4, discussed
further below). The memory 214 may further include calibration
information regarding the sensor, and system RF communication
parameters (i.e. the second RF communication scheme) employed by
the microcontroller 212 and/or RF communication circuit 210 to
transmit information to other devices.
[0046] The microcontroller 212 is a processing circuit operable to
control the general operation of the sensor module 204. In general,
however, the microcontroller 212 receives digital sensor
information from the signal processing circuit 216 and provides the
information to the local RF communication circuit 210 for
transmission to a local device, for example, the hub module 202.
The microcontroller 212 may cause the transmission of sensor data
from time-to-time as dictated by an internal counter or clock, or
in response to a request received from the hub module 202.
[0047] The microcontroller 212 is further operable to receive
configuration information via the RF communication circuit 210,
store configuration information in the memory 214, and perform
operations in accordance with such configuration information. As
discussed above, the configuration information may define which of
multiple possible sensor functionalities is to be provided by the
sensor module 204. The microcontroller 212 employs such information
to cause the appropriate sensor device or devices from the sensor
device suite 218 to be operably connected to the signal processing
circuit such that sensed signals from the appropriate sensor device
are digitized and provided to the microcontroller 212. As discussed
above, the microcontroller 212 may also use the configuration
information to format outgoing messages and/or control operation of
the RF communication circuit 210.
[0048] The MEMS local RF communication circuit 210 may suitably
include a Bluetooth RF modem, or some other type of short range
(about 30-100 feet) RF communication modem. The use of a MEMS-based
RF communication circuit allows for reduced power consumption,
thereby enabling the potential use of a true wireless, battery
operated sensor module 204. A suitable exemplary MEMS-based RF
communication circuit is discussed in the WINS Presentation.
[0049] As discussed above, it is assumed that the sensor module 204
is configured to operate as a temperature sensor. To this end, the
memory 214 stores information identifying that the sensor module
204 is to operate as a temperature sensor. Such information may be
programmed into the memory 214 via a wireless programmer. The
module 204 may be programmed upon shipment from the factory, or
upon installation into the building control system. The
microcontroller 212, responsive to the configuration information,
causes the signal processing circuit 216 to process signals only
from the temperature sensor, ignoring output from other sensors of
the sensor suite 218.
[0050] It will be appreciated that in other embodiments, the sensor
suite 218 may be replaced by a single sensor. However, additional
advantages may be realized through the use of a configurable sensor
module capable of performing any of a plurality of sensor
functions. As discussed further above, these advantages include the
reduction of the number of sensor module designs.
[0051] In addition, the reduced wiring requirements and the reduced
power consumption of the above described design provides benefits
even in non-battery operated sensors.
[0052] The sensor module 206 is configured to operate as a flow
sensor in the embodiment described herein. The sensor module 206
may suitably have the same physical construction as the sensor
module 204. To this end, the sensor module 206 includes a local RF
communication circuit 230, a microcontroller 232, a programmable
non-volatile memory 234, a signal processing circuit 236, a sensor
suite 238, and a power supply/source 240. In contrast to the sensor
module 204, however, the memory 234 of the sensor module 206
contains configuration information identifying that the sensor
module 206 is to function as a flow sensor.
[0053] The actuator module 208 is a device that is operable to
cause movement or actuation of a physical device that has the
ability to change a parameter of the building environment. For
example, the actuator module 208 in the embodiment described herein
is operable to control the position of a ventilation damper,
thereby controlling the flow of heated or chilled air into the
room.
[0054] The actuator module 208 is also preferably embodied as a
wireless integrated network device that incorporates
microelectromechanical system ("MEMS") devices. By way of example,
in the exemplary embodiment described herein, the actuator module
208 includes a MEMS local RF communication circuit 250, a
microcontroller 252, a programmable non-volatile memory 254, and a
signal processing circuit 256. The actuator module 208 also
contains a power supply/source 260. In the preferred embodiment
described herein, the power supply/source 260 is a battery, for
example, a coin cell battery. However, it will be appreciated that
if AC power is necessary for the actuator device (i.e. the damper
actuator), which may be solenoid or value, then AC power is readily
available for the power supply/source 260. As a consequence, the
use of battery power is not necessarily advantageous.
[0055] The actuator 262 itself may suitably be a solenoid, stepper
motor, or other electrically controllable device that drives a
mechanical HVAC element. In the exemplary embodiment described
herein, the actuator 262 is a stepper motor for controlling the
position of a vent damper.
[0056] The MEMS local RF communication circuit 250 may suitably be
of similar construction and operation as the MEMS local RF
communication circuit 210. Indeed, even if the MEMS local RF
communication circuit 250 differs from the RF communication circuit
210, it nevertheless should employ the same communication
scheme.
[0057] The microcontroller 252 is configured to receive control
data messages via the RF communication circuit 250. In the
embodiment described herein, the control data messages are
generated and transmitted by the hub module 202. The control data
messages typically include a control output value intended to
control the operation of the actuator 262. Accordingly, the
microcontroller 252 is operable to obtain the control output value
from a received message and provide the control output value to the
signal processing circuit 256. The signal processing circuit 256 is
a circuit that is configured to generate an analog control signal
from the digital control output value. In other words, the signal
processing circuit 256 operates as an analog driver circuit. The
signal processing circuit 256 includes an output 258 for providing
the analog control signal to the actuator 262.
[0058] The non-volatile memory 254 is a memory that contains
configuration and/or calibration information related to the
implementation of the actuator 262. The memory 254 may suitably
contain sufficient information to effect mapping between the
control variables used by the hub module 202 and the control
signals expected by the actuator 262. For example, the control
variables used by the hub module 202 may be digital values
representative of a desired damper position charge. The actuator
262, however, may expect an analog voltage that represents an
amount to rotate a stepper motor. The memory 254 includes
information used to map the digital values to the expected analog
voltages.
[0059] The hub module 202 in the exemplary embodiment described
herein performs the function of the loop controller (e.g. a PID
controller) for the space control subsystem 110. The hub module 202
obtains process variable values (i.e. sensor information) from
either or both of the sensor modules 204 and 206 and generates
control output values. The hub module 202 provides the control
output values to the actuator module 208. The hub module 202 also
communicates with external elements of the building control system,
for example, the supervisory computer, fan or chiller control
subsystems, and other room controller subsystems.
[0060] In the exemplary embodiment described herein, the hub module
202 further includes sensor functionality. In general, it is often
advantageous to combine the hub controller core functionality with
a sensor function to reduce the overall number of devices in the
system. Thus, some room control subsystems could include hub module
202 with an integrated temperature sensor and one or more actuator
modules. Separate sensor modules such as the sensor module 204
would not be necessary.
[0061] To accomplish these and other functions, the hub module 202
includes a network interface 270, a room control processor 272, a
non-volatile memory 274, a signal processing circuit 276, a MEMS
sensor suite 278 and a MEMS local RF communication circuit 280.
[0062] The network interface 270 is a communication circuit that
effectuates communication to one or more components of the building
control system that are not a part of the space control subsystem
110. Referring to FIG. 1, the network interface 270 is the device
that allows the space control subsystem 110 to communicate with the
supervisory computer 102, the fan controller subsystem 106, the
chiller controller subsystem 108 and/or the other room controller
subsystems.
[0063] Referring again to FIG. 2, to allow for wireless
communication between controller subsystems of the building control
system 100, the network interface 270 is preferably an RF modem
configured to communicate using the wireless area network
communication scheme. Preferably, the network interface 270 employs
a packet-hopping protocol to reduce the overall transmission power
required. In packet-hopping, each message may be transmitted
through multiple intermediate network interfaces before it reaches
its destination. Referring again to FIG. 1, if the space control
subsystem 110 sends a message to the fan control subsystem 106, the
network interface of the space control subsystem 110 provides the
message to the physically closest subsystem. Thus, in the
embodiment shown in FIG. 1, the network interface of the space
control subsystem 110 provides the message to the network interface
of the space control subsystem 112. The network interface of the
space control subsystem 112 reads the destination address of the
message and determines that the message is not intended to be
received at the space control subsystem 112. As a consequence, the
network interface of the space control subsystem 112 passes the
message along to the network interface of the next closes
subsystem, which is the space control subsystem 114. The network
interface of the space control subsystem 114 similarly passes the
message onto the fan control subsystem 116. The network interface
of the fan control subsystem 116, however, recognizes from the
destination address in the message that it is the intended
recipient. The network interface of the fan control subsystem 116
thus receives the message and processes it.
[0064] Referring again to FIG. 2, in order to facilitate the
wireless area network operation described above, the network
interface 270 is preferably operable to communicate using a short
range wireless protocol. The network interface 270 is further
operable to, either alone or in conjunction with the control
processor 272, interpret messages in wireless communications
received from external devices and determine whether the messages
should be retransmitted to another external device, or processed
internally to the hub module 202. As discussed above, if a
packet-hopping protocol is employed, the network interface 270 may
receive a message intended for another subsystem. In such a case,
the network interface 270 retransmits the message to another
device. However, if the network interface 270 includes a
temperature set point for the space control subsystem 110 of FIG.
2, then the network interface 270 passes the information to the
room control processor 272.
[0065] As discussed above, the hub module 202 may optionally
include sensor capability. To this end, the MEMS sensor suite 278
may suitably include a plurality of MEMS sensors, for example, a
temperature sensor, flow sensor, pressure sensor, and/or
gas-specific sensor. As with the sensor modules 204 and 206, the
hub module 202 may be programmed to enable the particular desired
sensing capability. In this manner, a single hub module design may
be manufactured to for use in a variety of HVAC sensing
applications, each hub module 202 thereafter being configured to
its particular use. (See e.g. FIGS. 3 and 4). However, it may be
sufficient to provide hub control modules having only temperature
sensing capability because rooms that employ an HVAC controller
also typically require a temperature sensor. Thus, a temperature
sensor on the hub module will nearly always fill a sensing need
when the hub module is employed.
[0066] The signal processing circuit 276 includes the circuitry
that interfaces with the sensor suite 278, converts analog sensor
signals to digital signals, and provides the digital signals to the
room control processor 272. As discussed above, examples of low
power, micro-electronic A/D converters and sensor interface
circuitry are shown in the WINS Presentation.
[0067] The programmable non-volatile memory 274, which may be
embodied as a flash programmable EEPROM, stores configuration
information for the hub module 274. By way of example, programmable
non-volatile memory 274 preferably includes system identification
information, which is used to associate the information generated
by the sensor module 274 with its physical and/or logical location
in the building control system. The memory 274 further includes
set-up configuration information related to the type of sensor
being used. The memory 274 may further include calibration
information regarding the sensor, and system RF communication
parameters employed by the control processor 272, the network
interface 270 and/or the local RF communication circuit 280.
[0068] The MEMS local RF communication circuit 280 may suitably
include a Bluetooth RF modem, or some other type of short range
(about 30-100 feet) RF communication modem. The MEMS local RF
communication circuit 280 is operable to communicate using the same
RF communication scheme as the MEMS local RF communication circuits
210, 230 and 250. As with the sensor module 204, the use of a
MEMS-based RF communication circuit allows for reduced power
consumption, thereby enabling the potential use of a true wireless,
battery operated hub module 202. Moreover, it may be possible and
preferable to employ many of the same RF elements in both the local
RF communication circuit 280 and the network interface 270. Indeed
in some cases, the local RF communication circuit 280 and the
network interface 270 are substantially the same circuit. In any
event, a suitable MEMS-based RF communication circuit is discussed
in the WINS Presentation.
[0069] The control processor 272 is a processing circuit operable
to control the general operation of the hub module 274. In
addition, the control processor 272 implements a control transfer
function to generate control output values that are provided to the
actuator module 208 in the space control subsystem 110. To this
end, the control processor 272 obtains sensor information from its
own sensor suite 278 and/or from sensor modules 204 and 206. The
control processor 272 also receives a set point value, for example,
from the supervisory computer 102 via the network interface 270.
The control processor 272 then generates the control output value
based on the set point value and one or more sensor values. The
control processor 272 may suitably implement a
proportional-integral-differential (PID) control algorithm to
generate the control output values. Suitable control algorithms
that generate control output values based on sensor or process
values and set point values are known.
[0070] Exemplary sets of operations of the room control system 110
is shown in FIGS. 3, 4 and 5. In general, FIGS. 3, 4 and 5
illustrate how the hub module 202, the sensor module 204 and
actuator 208 operate to attempt to control aspects of the
environment of the room. More specifically, FIG. 3 shows an
exemplary set of operations of the hub module 202, FIG. 4 shows an
exemplary set of operations of the sensor module 204, and FIG. 5
shows an exemplary set of operations of the actuator module
208.
[0071] Referring particularly to FIG. 3, the operations shown
therein will be described with contemporaneous reference to FIG. 2.
The operations of FIG. 3 are performed by the room control
processor 272, which generally controls the operation of the hub
module 202.
[0072] Steps 302, 304 and 306 all represent operations in which the
room control processor 272 receives input values from various
sources. The order in which those steps are performed is not of
critical importance.
[0073] In step 302, the processor 272 receives a flow value from
the sensor module 206, which in the exemplary embodiment described
herein has been configured as a flow sensor module. To receive a
flow value from the sensor module 206, the processor 272 causes the
local RF communication circuit 280 to be configured to receive a
transmitted message from the local RF communication circuit 230 of
the sensor module 206. When a message is received, the local RF
communication circuit 280 and/or the processor 278 verify the
source and intended destination of the message. If the message is
legitimately intended for the hub module 202, then the processor
278 parses the sensor value from the message for subsequent
use.
[0074] In step 304, the processor 272 receives temperature
measurement values from the sensor module 204 as well as its
internal temperature sensor device 278. In many cases, only a
single temperature sensor value is necessary, in which case the hub
module 202 need not include the temperature sensor 278, or,
alternatively, the sensor module 204 would not be necessary. In the
exemplary embodiment described herein, however, it will be assumed
that the processor 272 receives temperature values from both the
temperature sensor device 278 and the sensor module 204. To receive
a temperature value from the sensor module 204, the processor 272
and local RF communication circuit 280 operate in the same manner
as that described above in connection with receiving flow sensor
values from the sensor module 206. To receive a temperature value
from the sensor 278, the processor 272 receives digital sensor
information from the signal processing circuit 276.
[0075] In step 306, the processor 272 obtains a set point value
through the network interface 270. In particular, in the embodiment
described herein, the set point temperature for the room in which
the control subsystem 110 is disposed is provided from a device
external to the control subsystem 110. For example, the supervisory
computer 102 of FIG. 1 may provide the temperature set points for
all of the space control subsystems 110, 112 and 114 in the
building control system 100. It will be noted, however, that in
alternative embodiments, the set point may be derived from a
manually-adjustable mechanism directly connected to the hub module
202.
[0076] To receive the set point value from the external device, the
network interface 270 monitors transmissions in the WAN on which
the various subsystems communicate. If a message including a set
point intended for the space control subsystem 110 is received by
the network interface 270, then that message will be provided to
the processor 272. In such a case, the processor 272 parses out the
set point information for subsequent use, such as use in the
execution of step 308, discussed below.
[0077] In step 308, the processor 272 generates a control output
value based on the most recently received set point value and
temperature sensor values. To this end, the processor 272 may
suitably employ a PID controller algorithm to generate the control
output value. In the embodiment described herein, the control
output value is representative of a desired change in a vent damper
position. For example, if chilled air is provided through the vent,
and the sensor temperature value exceeds the set point temperature
value, then the control output value identifies that the vent
damper must be opened further. Further opening the vent damper
allows more chilled air to enter the room, thereby reducing the
temperature.
[0078] A PID control algorithm that is capable of generating a vent
damper position based on a difference between temperature sensor
values and a set point temperature value would be known to one of
ordinary skill in the art. In general, it will be noted that the
use of particular control system elements such as temperature
sensors, set point temperatures, and vent dampers are given by way
of illustrative example. The use of control systems and subsystems
with reduced wiring as generally described herein may be
implemented in control systems implementing a variety of sensor
devices and actuators or other controlled devices.
[0079] Referring again to the specific embodiment described herein,
it will be appreciated that during ongoing operation, the processor
272 does not require an update in each of steps 302, 304 and 306
prior to performing step 308. Any update received in any of those
steps can justify a recalculation of the control output value.
Moreover, the processor 272 may recalculate the control output
value on a scheduled basis, without regard as to which input values
have changed.
[0080] In step 310, the processor 272 causes the generated control
output value to be communicated to the actuator module 208. To this
end, the processor 272 and the local RF communication circuit 280
cooperate to generate a local RF signal that contains information
representative of the control output value. The processor 272 may
suitably add a destination address representative of the actuator
module 208 to enable the actuator module 208 to identify the
message.
[0081] It is noted that in the exemplary embodiment described
herein, the flow sensor value received from the flow sensor module
206 is not used in the. PID control calculation performed by the
processor 272. That value is obtained so that it may be used by
other subsystems or by the supervisory computer 102. Indeed,
multiple sensor values are typically communicated to external
subsystems.
[0082] To this end, in step 312, the processor 272 causes the
network interface 270 to transmit received sensor values to devices
external to the room control subsystem 110. For example, the
processor 272 may cause temperature and flow sensor values to be
transmitted to the supervisory computer 102. The supervisory
computer 102 may then use the information to monitor the operation
of the building control system. Moreover, temperature and/or flow
sensor values from various space control subsystems may be employed
by the fan control subsystem 108 to adjust operation of one or more
ventilation fans, or by the chiller control subsystem 106 to adjust
operation of the chiller plant. Accordingly, the processor 272 must
from time to time cause sensor values generated within the space
control subsystem 110 to be communicated to external devices
through the network interface 270.
[0083] The room control processor 272 repeats steps 302-312 on a
continuous basis. As discussed above, the steps 302-312 need not be
performed in any particular order. New sensor and/or set point
values may be received periodically either on a schedule, or in
response to requests generated by the processor 272.
[0084] With regard to the sensor values, FIG. 4 shows an exemplary
set of operations performed by the sensor module 204 in generating
and transmitting temperature sensor values to the hub module 202 in
accordance with step 302 of FIG. 3. The sensor module 206 may
suitably perform a similar set of operations to generate and
transmit flow sensor values to the hub module 202 in accordance
with step 304 of FIG. 3.
[0085] Referring now to FIG. 4, the operations shown therein are
performed by the microcontroller 212 of the sensor module 204. In
step 402, the microcontroller 212 determines whether it is time to
transmit an updated temperature value to the hub module 202. The
determination of when to transmit temperature values may be driven
by a clock internal to the sensor module 204, or in response to a
request or query received from the hub module 202, or both. In
either event, if it is not time to transmit an update, the
microcontroller 212 repeats step 402.
[0086] If, however, it is determined that an update should be
transmitted, then the microcontroller 212 proceeds to step 404. In
step 404, the microcontroller 212 obtains a digital value
representative of a measured temperature from the signal processing
circuit 216. To this end, the microcontroller 212 preferably "wakes
up" from a power saving mode. The microcontroller 212 preferably
also causes bias power to be connected to power consuming circuits
in the signal processing circuit 216, such as the A/D converter. In
this manner, power may be conserved by only activating power
consuming circuits when a temperature sensor value is specifically
required. Otherwise, the power consuming devices remain
deactivated. Thus, for example, if a temperature value need only be
updated every fifteen seconds, many of the power consuming circuits
would only be energized once every fifteen seconds. However, it is
noted that if the power source 220 is derived from AC building
power, the need to reduce power consumption is reduced, and the
microcontroller 212 and the signal processing circuit 216 may
receive and process digital temperature sensing values on an
ongoing basis.
[0087] In any event, after step 404, the microcontroller 212
proceeds to step 406. In step 406, the microcontroller 212 converts
the sensed digital temperature value into the format expected by
the room control processor 272 of the hub module 202. The
microcontroller 212 further prepares the message for transmission
by the local RF communication circuit 210. Once the message
including the sensor temperature value is prepared, the
microcontroller 212 in step 408 causes the local RF communication
circuit 210 to transmit the message. The message is thereafter
received by the hub module 202 (see step 304 of FIG. 3).
Thereafter, the microcontroller 212 may return to step 402 to
determine the next time an update is required.
[0088] FIG. 5 shows an exemplary set of operations that may be
performed by the microcontroller 252 of the actuator module 208. As
discussed above, one purpose of the space control subsystem 110 is
to control the physical operation of a device to help regulate a
process variable, in this case, the room temperature. The actuator
module 208 thus operates to carry out the actions determined to be
necessary in accordance with the control algorithm implemented by
the room process controller 272.
[0089] First, in step 502, a message which may include the control
output value is received from the hub module 202. To this end, the
RF communication circuit 250 receives the message and provides the
message to the microcontroller 252. Thereafter, in step 504, the
microcontroller 252 determines whether the received message is
intended for receipt by the actuator module 208. If not, then the
microcontroller 252 returns to step 502 to await another incoming
message.
[0090] If, however, the microcontroller 252 determines in step 504
that the received message is intended for the actuator module 208,
then the microcontroller 252 proceeds to step 506. In step 506, the
microcontroller 252 parses the message to obtain the actuator
control output value, and converts that value into a value that
will cause the actuator to perform the requested adjustment. For
example, if the received control output value identifies that the
ventilator damper should be opened another 10%, then the
microcontroller 252 would generate a digital output value that,
after being converted to analog in the signal processing circuit
256, will cause the actuator 258 to open the ventilator damper
another 10%.
[0091] In step 508, the microcontroller 252 actually provides the
digital output value to the signal processing circuit 256. The
signal processing circuit 256 then converts the value to the
corresponding analog voltage expected by the actuator device 258.
Thereafter, the microcontroller 252 returns to step 502 to await
the next message received from the hub module 202.
[0092] The above described space control subsystem 110 is merely an
exemplary illustration of the principles of the invention. The
principles of the invention may readily be applied to control
subsystems having more or less sensors or actuators, as well as
other elements.
[0093] The relatively low power requirements enabled by the use of
MEMS devices and local RF communications in the sensor modules and
even the hub module allow for implementation of the modules in
battery operated format. Thus, a mostly wireless building control
system may be developed. However, as discussed above, many
advantages of the present invention may be obtained in systems that
use other forms of power.
[0094] FIG. 6 shows an exemplary embodiment of the space control
subsystem 114 of the building control system 100 of FIG. 1. The
space control subsystem 114 of FIG. 6 is used in a space or room
610 that includes two fume hoods 612 and 614. A fume hood, as is
known in the art, is a fume collection device disposed over an
enclosed surface. The fume hoods 612 and 614 allow for experiments
or processes that involve noxious gasses fumes by conducting those
gasses away from the experimental area.
[0095] The room 610 is coupled in an air communication relationship
with an air flow supply duct 618 in which are disposed a supply
damper 620 and a radiator or heating coil device 616. The room 610
is also coupled to communicate air to an exhaust duct 622 through a
main exhaust damper 624. Fume hood dampers 626 and 628 communicate
air/gas within the fume hoods 612 and 614, respectively, to the
exhaust duct 622.
[0096] The space control subsystem 114 is designed to both regulate
the temperature within the room 610 as well as ensure that the fume
hoods 612 and 614 achieve their purpose in conducting away gasses.
For ordinary temperature regulation, the space control subsystem
114 controls the operation of the supply damper 620 and the heating
coil 616 to control the supply of heated or cooled air into the
room 610. The space control subsystem 114 control the main exhaust
damper 624 in a coordinated fashion with the supply damper 620 to
ensure sufficient fresh air and proper atmospheric pressure is
maintained within the room 610. For conducting away noxious gasses,
the space control subsystem 114 controls the operation of the fume
hood dampers 626 and 628 to conduct gasses away when their presence
is detected. The supply damper 620 and/or the main exhaust damper
624 is also controlled in a coordinated manner to ensure that the
required air flow to conduct gasses away is available through the
appropriate fume hood damper 626 or 628.
[0097] To this end, the space control subsystem 114 includes a
control module 630, a supply flow module 632, a main exhaust module
634, a first fume hood exhaust module 636, a second fume hood
exhaust module 638, a first fume hood sensor module 640, and a
second fume hood sensor module 642.
[0098] The control module 620 generally operates to effectuate
communication between the space control subsystem 114 and the other
subsystems of the building control system 100 (see FIG. 1). In the
embodiment described herein, the control module 620 further
includes a temperature sensor. The supply flow module 632 controls
the supply damper 620 to regulate the supply of air flow into the
space 610, and further controls the supply of heat (or cool) water
to the heating coil element 616 disposed in the path of the air
flow supply. The main exhaust module 634 controls the main exhaust
damper 624 to regulate the flow of air out of the space 610, such
that in general the atmospheric pressure within the room is
controlled by the cooperative efforts of the supply flow module 622
and the main exhaust module 624.
[0099] The first fume hood exhaust module 636 controls the damper
626 to control the exhaust or venting of fumes or gas from within
or in the vicinity of the fume hood 612. The second fume hood
exhaust module 638 controls the damper 628 to control the exhaust
or venting of fumes or gas from within or in the vicinity of the
fume hood 614. The first fume hood sensor module 640 is operable to
obtain measurements indicative of the concentration of a gas within
the fume hood 612, while the second fume hood sensor module 642 is
operable to obtain measurements indicative of the concentration of
a gas with the fume hood 614.
[0100] FIGS. 7a-b, 8a-c, 9a-b, 10a-b and 11a-b describe the
structure and operation of the various modules 630 through 642 of
the space control subsystem 114 in order to carry out the above
described control operations. In particular, FIGS. 7a and 7b
describe the structure and operation of the control module 630,
FIGS. 8a, 8b and 8c describe the structure and operation of the
supply module 632, FIGS. 9a and 9b describe the structure and
operation of the main exhaust module 634, FIGS. 10a and 10b
describe the structure and operation of the first fume hood sensor
module 640 (which is also applicable to the second fume hood sensor
module 642), and FIGS. 11a and 11b describe the structure and
operation of the first fume hood exhaust module 636 (which is also
applicable to the second fume hood exhaust module 638).
[0101] Preferably, all of the modules 630, 632, 634, 636, 638, 640
and 642 are constructed of a uniform basic module design, and then
individually configured to carry out the particular operations
described below. To this end, FIGS. 12a and 12b show an exemplary
embodiment of a flexible, MEMS-based module design that is
particularly useful in building control, automation, comfort,
security and/or safety systems.
[0102] Referring to FIGS. 12a and 12b, the module 1200 is
implemented as a single, self-powered, standalone device in which
most of the active components are integrated onto one or two
semiconductor substrates.
[0103] As shown in FIG. 12a, the module 1200 in the embodiment
described herein includes a top semiconductor layer 1202, a lithium
ion battery layer 1204 and a bottom semiconductor layer 1206. The
various functions of the module 1200, discussed below in connection
with FIG. 12b, are incorporated into the top and bottom
semiconductor layers 1202 and 1206. The lithium ion battery layer
1204 provides a source of electrical power to the top and bottom
semiconductor layers 1202 and 1206. The lithium ion battery layer
1204 is preferably disposed between the top and bottom
semiconductor layers 1202 and 1206 to provide an advantageous,
space-efficient layout. Various interconnects may be provided
between the two semiconductor layers 1202 and 1206 around the
lithium ion battery layer 1204 as need. In the alternative, one of
the two layers may be dedicated completely to a light-powered
recharging circuit for the lithium ion battery layer 1204. In
another alternative, all of the elements of the module 1200 may be
implemented onto a single semiconductor substrate such as the layer
1202.
[0104] FIG. 12b shows a block diagram representation of the module
circuits 1250 that are implemented into the semiconductor layers
1202 and 1206 of the module 1200. The module circuit 1250 include a
sensor suite 1252, an EEPROM 1254, a processing circuit 1256, a
power management circuit 1258 and an RF communication circuit
1260.
[0105] The RF communication circuit 1260 is a MEMS based
communication circuit such as that described above in connection
with FIG. 2. The RF communication circuit 1260 is preferably
configured to communicate using at least one local RF communication
format, such as Bluetooth.
[0106] The power management circuit 1258 that preferably operates
to recharge the lithium ion battery layer 1204 of FIG. 6, and may
include semiconductor devices that convert light or RF energy into
electrical energy that may be used to trickle charge the lithium
ion battery.
[0107] The sensor suite 1252 is collection of MEMS sensors
incorporated into a single substrate. The incorporation of multiple
MEMS sensor technologies is known. For example, Hydrometrics offers
for sale a MEMS sensor device that includes both temperature and
humidity sensing functions. MEMS based light, gas content,
temperature, flow, smoke and other sensing devices are known. Such
devices are in the embodiment described herein implemented onto a
single substrate 1202 or 1206, or pair of substrates 1202 and
1206.
[0108] The processing circuit 1256 incorporates a microprocessor or
microcontroller, as well as microelectronics A/D circuits for
connecting to the MEMS sensor devices of the sensor suite 1252. As
such, the processing circuit 1256 performs the operations described
above in connection with the signal processing circuit 216 and
controller 212 of the sensor module 204 of FIG. 2.
[0109] The EEPROM 1254 (which may be another type of non-volatile,
chip-based memory such as ferro-electric or ferro-magnetic RAM) is
a non-volatile memory that stores the configuration information for
the module 1200. For example, the EEPROM 1254 may store ID
information used to identify the module 1200 to the system in which
it is connected. The EEPROM 1254 also stores information related to
the function in which the module 1200 will be used. For example,
the EEPROM 1254 may store information identifying that the module
1200 should enable its temperature sensing function as opposed to
any of its other possible sensing functions.
[0110] As discussed above in connection with FIG. 2, the
configuration information in the EEPROM 1254 may simply identify
the intended functionality of the module 1200, which would then
cause the processing circuit 1256 to execute portions of program
code stored in ROM (not shown) to carry out that identified
functionality. To this end, the EEPROM 1254 may be replaced by a
set of DIP switches that may be manually manipulated to set the
configuration of the module 1200. In either case, such embodiments
would require that most of the program code for a variety of
different sensor functions be stored in ROM, only a portion of
which would be used once the configuration information is
received.
[0111] However, in one embodiment of the invention, most or all of
the code unique to the selected function of the module is
downloaded into the EEPROM 1254 during configuration of the device.
Thus, if the module 1200 is to operate as a temperature sensor
module, then all appropriate code for a temperature sensor module
is downloaded to the EEPROM 1254, as is identification information
and calibration information. This method provide maximum
flexibility because a single module 1200 may be programmed to do
many custom tailored tasks, in addition to performing sensor
functions.
[0112] Regardless of whether the EEPROM 1254 is configured via
large amounts of programming code, or through flags and parameters
that are used to select pre-existing code within the module 1200,
the configuration information is downloaded to the EEPROM 1254 from
an external device, for example, a portable programming device. In
particular, a portable programming device provides programming
instructions via RF signals to the RF communication circuit 1260.
The processing circuit 1256 obtains the programming instructions
from the RF communication circuit 1260 and stores the instructions
into the EEPROM 1254. It will be appreciated that other techniques
for providing configuration information to the EEPROM 1254 may be
used.
[0113] Thus, the above described module 1200 may readily be
configured as any one of a large plurality of sensor types or even
other types of building automation system components. As a
consequence, large amounts of the devices may be fabricated,
thereby reducing the per-unit tooling and design costs associated
with ordinary building automation sensors. In addition, the highly
integrated nature of the devices reduces shipping and storage
costs, as well as reduces power consumption. It will be noted that
the design of the module 1200 may be used as the sensor modules
204, 206 in the exemplary space control subsystem 200 of FIG. 2,
and may also be used as the hub module 202. In such a case, the
network interface 270 of the hub module 202 may be configured to
operate via the RF communication circuit 1260 of the module 1200 of
FIGS. 12a and 12b.
[0114] Returning now to the discussion of the subsystem 114 of FIG.
6, it will be assumed that in the embodiment described herein that
the modules 630, 632, 634, 636, 638, 640 and 642 all employ the
design and construction of the module 1200 of FIGS. 12a and 12b.
However, it will be appreciated that other assemblies of those
circuits may be employed and achieve at least some of the benefits
of the invention.
[0115] The individual modules 630, 632, 634, 636, 638, 640 and 642
of FIG. 6 are now described in further detail.
[0116] Referring to the control module 630, FIG. 7a shows an
exemplary block diagram of the control module 630, while FIG. 7b
shows an exemplary flow diagram of the operations performed by the
control processor of the control module 630. In the exemplary
embodiment describe herein, the control module 630 cooperates with
the supply module 632 and main exhaust module 634 to control the
temperature in the room 610. As discussed above, the control module
630 also facilitates communication of information, if necessary,
between any of the modules 630-642 and elements of other subsystems
of the building control system 100 (see FIG. 1).
[0117] As discussed above, the control module 630 has a general
construction substantially similar to the module 1200 of FIGS. 12a
and 12b. To this end, the control module 630 includes an RF
communication circuit 705, a power management circuit 710, a
processing circuit 715, an EEPROM 720, and a sensor suite 725. Each
of the elements of the control module operates generally as
described above in connection with FIGS. 12a and 12b.
[0118] The control module 630 includes a temperature sensing
functionality. As a consequence, the EEPROM 720 includes
configuration information identifying that processing circuit 715
should obtain and process temperature measurement information from
the MEMS sensor suit 725. In the exemplary embodiment described
herein, the EEPROM 720 further includes sufficient program
instructions or code to carry out the operations illustrated in
FIG. 7b and described below.
[0119] The RF communication circuit 705 is preferably configured to
communicate with the other elements of the subsystem 114 as well as
in the local area network between subsystems. To this end, the RF
communication circuit 705 may be able to communicate using the two
different communication schemes described above in connection with
FIGS. 1 and 2. In particular, one scheme would be used for
communications within the subsystem 114 and the other scheme would
be used to communicate to other subsystems and devices external to
the subsystem 114. Alternatively, the RF communication circuit 705
may instead communicate using only a single RF communication
scheme. External communications would be carried out through a
separate network interface device, not shown, that is itself
capable of communicating using the two different communication
schemes.
[0120] The operation of the control module 630 is described with
reference to FIG. 7b, which shows an overview of the functions of
the processing circuit 715. With reference to FIG. 7b, in step 750,
the processing circuit 715 receives from time to time a room
temperature set point value W.sub.T. To this end, the RF
communication circuit 705 receives the information within
communication signals from one or more devices external to the
subsystem 114 such as, for example, the supervisory computer 102 of
FIG. 1. The RF communication circuit 705 then provides the
information to the processing circuit 715. Alternatively, all or
part of the temperature set point may be provided via a manual
control device disposed within the room 610.
[0121] Also in step 750 the processing circuit 715 receives the set
points W.sub.G1FL and W.sub.G2FL from, respectively the fume hood
exhaust modules 636 and 638. The processing circuit 715 also
receives the measured exhaust flow X.sub.FLO from the main exhaust
module 634. The processing circuit 715 receives such information
from transmitted RF signals from the modules 634, 636 and 638 via
the RF communication circuit 705.
[0122] Referring to FIG. 6, the set points W.sub.G1FL and
W.sub.G2FL represent the exhaust air flow through the exhaust
dampers 626 and 628 from the fume hoods 612 and 614, respectively.
As discussed below in connection with step 770, the control module
630 uses the values W.sub.G1FL and W.sub.G2FL to adjust the supply
flow to accommodate any additional outflow through the dampers 626
and 628. In particular, whenever it becomes necessary to vent fumes
through the fume hood via either of the dampers 626 or 628, the
supply flow at the supply damper 620 is increased to provide
additional air pressure to force air flow through the dampers 626
and/or 628. However, it will be appreciated that instead of
increasing the supply flow when it becomes necessary to vent fumes
through the fume hood(s), the supply flow may remain constant and
the main exhaust damper 624 may be further closed or restricted to
force exhaust air flow through the fume hood exhaust dampers 626
and/or 628. Alternatively, a combination of partially closing off
the main exhaust damper 624 and further opening the supply damper
620 may be used. However, in the exemplary embodiment described
herein, the supply damper 620 is adjusted to compensate for
additional (or decreased) flow cause by opening (or closing) the
fume hood exhaust dampers 626 and/or 628. For this reason, the
processing circuit 715 receives W.sub.G1FL and W.sub.G2FL in step
750, as well as W.sub.T.
[0123] In step 755, the processing circuit 715 also receives from
time to time a room temperature measurement value X.sub.T. To this
end, the processing circuit 715 obtains an analog temperature
measurement value from the temperature sensor element within the
MEMS sensor suite 725 and converts the analog temperature
measurement value to a representative digital value thereof
X.sub.T.
[0124] In step 760, the processing circuit 715 generates a
temperature control output value Y.sub.T. The value Y.sub.T
actually represents an interim value in the system indicative of
how the system must change to achieve the temperature set point
W.sub.T. Thus, Y.sub.T is a function of W.sub.T and X.sub.T. By way
of a simple example, Y.sub.T may suitably be set to the error
signal W.sub.T-X.sub.T.
[0125] Thereafter in step 765, the processing circuit 715
calculates the main exhaust set point W.sub.FLO based on the
current exhaust X.sub.FLO and the temperature control output
Y.sub.T. The function that determines W.sub.FLO carries out the
operations set forth below.
[0126] In general, if the temperature is too high within the room
610 (i.e. Y.sub.T is a negative number), then additional cool air
should be supplied to the room 610. It is assumed that the supply
duct 618 moves cooling air into the room 610 when the heating coil
616 is not actuated. Thus, if Y.sub.T is a negative number, then
the additional flow from the supply duct 618 is required. Instead
of directly increasing the supply flow, however, the main exhaust
flow set point W.sub.FLO is increased in step 765. As will be
discussed below in connection with step 770, the supply flow set
point, W.sub.FL, will also be adjusted accordingly. The resulting
increase in the supply flow and exhaust flow moves more cool air
into the room, thereby reducing the temperature within the
room.
[0127] If, instead, the temperature is too low within the room 610,
(i.e. Y.sub.T is a positive number), then the flow of cool air from
the supply duct 618 should be decreased. To this end, the main
exhaust flow set point W.sub.FLO is adjusted downward, if possible.
The reduction in the exhaust flow and corresponding reduction in
supply flow (see step 770) reduces the flow of cool air into the
room 610 and should result in an increase in the temperature. If,
the main exhaust flow is already minimized, in other words, the
main exhaust damper 624 is substantially closed, then the main
exhaust flow set point W.sub.FLO cannot be adjusted further
downward. The determination as to whether the main exhaust damper
624 is substantially closed is based on the exhaust flow X.sub.FLO
value.
[0128] The above described functionality of step 765 may readily be
carried out by any number of suitable function definitions that
determine W.sub.FLO based on Y.sub.T and X.sub.FLO.
[0129] In step 770, the processing circuit 715 calculates the
supply flow set point W.sub.FL based on the exhaust flow set point
W.sub.FLO and the two fume hood exhaust flow set points, W.sub.G1FL
and W.sub.G2FL. To this end, it will be appreciated that in the
exemplary embodiment shown in FIG. 6, the total air flowing out of
the room 610 flows through the main exhaust damper 624, the first
fume hood exhaust damper 626 and the second fume hood exhaust
damper 628. Accordingly, to avoid unduly pressurizing and/or
depressurizing the room, the supply flow set point W.sub.FL is set
to accommodate to the three exhaust flow set points. In a simple
example, W.sub.FL=W.sub.FLO+W.sub.G1FL+W.sub.G2FL.
[0130] It will be appreciated that as the exhaust flow W.sub.FLO is
increased or decreased in step 765, the supply flow exhaust point
W.sub.FL should increase or decrease accordingly.
[0131] Likewise, the supply flow increases or decreases responsive
to the change of either of the fume hood exhausts. For example, if
the fume hood 612 must be vented, then the first fume hood exhaust
flow set point W.sub.G1FL is increased (see FIGS. 10 and 11) and
the supply flow set point W.sub.FL is increased accordingly. As a
consequence, the subsystem 114 automatically increases air flow
into the room 610 to supply the needed additional pressure to vent
fumes through the fume hood exhaust dampers 626 and/or 628.
[0132] Thus, in step 770, the supply flow set point W.sub.FL is set
responsive to based on the exhaust flow set points W.sub.FLO,
W.sub.G1FL, and W.sub.G2FL.
[0133] In step 775, the processing circuit 715 determines the
heating coil set point W.sub.HC based on the temperature control
value Y.sub.T and the supply flow set point W.sub.FL. In general,
if the temperature in the room remains low (i.e. Y.sub.T is
positive) for a long time, it is indicative that the attempts to
raise the temperature through control of the air flow (in steps 765
and 770) were not successful. In such a case, the heating coil 616
should be turned on. To this end, the heating coil set point
W.sub.HC is determined based on the value of Y.sub.T over time. In
addition, the amount of heating provided by the convection air flow
over the heating coil 616 depends in part on the air flow rate past
the heating coil 616. Accordingly, the heating coil set point
W.sub.HC is also preferably determined as a function of the supply
flow set point W.sub.FL.
[0134] Thus, the above steps 765 and 770 regulate the supply flow
of cooler air into the room 610 to control the temperature.
However, if such regulation cannot adequately raise the temperature
of the room 610, then the heating coil 616 is used to help regulate
temperature in step 775. For example, the supply flow of cooler air
in some cases cannot be reduced (to raise room temperature) because
of the need for air flow to vent gasses out of the fume hoods 612
and/or 614. Thus, even though a low temperature may indicate that
the supply flow should be reduced, the supply flow cannot be
reduced without jeopardizing fume hood operation. In such cases,
the heating coil 616 is actuated and the supply flow actually
provides warm air that raises the room temperature.
[0135] It will be appreciated that other methods may be used to
regulate temperature within a space or room while adjusting the
supply flow and/or exhaust flow to compensate for the need to vent
air through the fume hoods 612 and/or 614.
[0136] In any event, in step 780, the processing circuit 715 causes
the RF communication circuit 705 to communicate the room flow set
point W.sub.FL and the heating coil set point W.sub.HC to the
supply flow module 632, and to communicate the exhaust flow set
point W.sub.FLO to the main exhaust module 634. Operation of the
supply flow module 632 is discussed below in connection with FIGS.
8a, 8b and 8c. Operation of the main exhaust module 634 is
discussed below in connection with FIGS. 9a and 9b.
[0137] The processing circuit 715 thereafter periodically receives
updates of X.sub.FLO, W.sub.G1FL, W.sub.G2FL, and/or W.sub.T via
the RF communication circuit 705, and updates of the measured
temperature X.sub.T from the sensor suite 725. While these updates
are typically interrupt-based, such that reception of one of the
values causes recalculation of one or more of the values W.sub.FLO,
W.sub.FL or W.sub.HC, another suitable update and recalculation
scheme would involve periodically requesting updates to any or all
of W.sub.G1FL, W.sub.G2FL, W.sub.T and/or X.sub.T. In either event,
upon receiving one or more updates, the processing circuit 715
preferably repeats of steps 760, 765, 770, 775 and 780.
[0138] It will thus be noted that the steps 750 through 780 need
not be executed in the order illustrated in FIG. 7b, nor must both
steps 750 and 755 be executed prior to each subsequent execution of
steps 760 through 780. However, over the course of operation, steps
750 through 780 will be executed repeatedly.
[0139] The above steps illustrate how the control module 630 may
determine the set point for the supply flow damper 620, the exhaust
flow damper 624 and the heater coil 616 in order to control the
room temperature. It will be appreciated that the control module
730 may readily be adapted to other methods to control the
temperature. The control module 630 further adjusts the supply flow
as necessary to compensate for the need for additional air flow to
vent fumes out of this exhaust dampers 626 and/or 628.
[0140] It is noted, however, that the control module 730 does not
directly cause actuators of the heating coil or air flow equipment
to act. Instead, the control module 730 merely obtains the set
points, W.sub.FLO, W.sub.FL and W.sub.HC, for such equipment. The
actuators for the supply damper 620 and heater coil 616 are
controlled by the supply flow module 632. The actuator for the main
exhaust damper 624 is controlled by the main exhaust module
634.
[0141] Referring now specifically to FIG. 8a, the supply flow
module 632 has a general construction substantially similar to the
module 550 of FIGS. 12a and 12b. To this end, the supply flow
module 632 includes an RF communication circuit 805, a power
management circuit 810, an processing circuit 815, an EEPROM 820,
and a sensor suite 825. Each of the elements of the control module
operates generally as described above in connection with FIGS. 12a
and 12b.
[0142] The control module 830 includes a flow sensing
functionality, and is further configured to generate actuator
output signals. The actuator output signals may suitably be
provided as analog output pins 815a, 815b on the processing circuit
815. The actuator output signals are analog outputs that control
the operation of actuators for the heating coil 616 and the damper
620. To this end, the analog output pins 815a and 815b are
connected to external actuators 817 and 818.
[0143] To enable the flow sensing functionality, the EEPROM 820
includes configuration information identifying that the processing
circuit 815 should obtain an air flow measurement information from
the MEMS sensor suit 825. In the exemplary embodiment described
herein, the EEPROM 820 further includes sufficient program
instructions or code to carry out the operations illustrated in
FIGS. 8b and 8c and described below.
[0144] The RF communication circuit 805 is preferably configured to
communicate with the other elements of the subsystem 114. As
discussed above, the RF communication circuit 805 may suitably be
configured to use Bluetooth or another local RF communication
protocol.
[0145] The operation of the supply flow module 632 is described
with reference to FIGS. 8b and 8c, which show an overview of two
separate functions of the processing circuit 815. FIG. 8b shows the
function related to regulation of the supply air flow in the room
610 while FIG. 8c shows the function related to control of the
heater coil 616.
[0146] With reference to FIG. 8b, in step 850, the processing
circuit 815 receives from time to time (via the RF communication
circuit 805) the set points W.sub.FL and W.sub.HC from the control
module 630. The use of the heating coil set point W.sub.HC is
discussed further below in connection with step 880 of FIG. 8c.
[0147] In step 855, the processing circuit 815 also receives a
supply air flow measurement value X.sub.FL. To this end, the
processing circuit 815 obtains an analog flow measurement value
from the flow sensor element within the MEMS sensor suite 825 and
converts the analog flow measurement value to a digital value
representative thereof, X.sub.FL.
[0148] In step 860, the processing circuit 815 calculates a supply
flow damper control output Y.sub.FL based on the measured flow
X.sub.FL and the set point value W.sub.FL. To this end, the
processing circuit 815 may use an ordinary PID algorithm.
[0149] In step 865, the processing circuit 815 provides an actuator
output signal corresponding to Y.sub.FL to its output 815a, which
in turn provides to the actuator 817 that causes mechanical
adjustment of the supply flow damper 620.
[0150] As with the processing circuit 715 of FIG. 7a, the
processing circuit 815 thereafter periodically receives updates of
its inputs and recalculates the output value of step 860. Steps
850, 855, 860 and 865 need not be executed in the order illustrated
in FIG. 8b.
[0151] FIG. 8c shows a flow diagram of the steps of the processing
circuit 815 in controlling the actuator 818 of the heater coil 616.
In step 880, the processing circuit 815 receives the heating coil
set point W.sub.HC through the RF communication circuit 805. The
processing circuit 815 thereafter in step 885 sets the actuator
control output Y.sub.HC to value that is the functional equivalent
of W.sub.HC and provides Y.sub.HC to the output 815b. The heating
coil actuator control output Y.sub.HC then propagates to the
actuator 818. The actuator 818 thereafter affects the operation of
the heating coil 616 in a manner responsive to the control output
Y.sub.HC in a manner that would be known to those of ordinary skill
in the art.
[0152] The processing circuit 815 may thereafter receive periodic
updates, via request or otherwise, and then repeat steps 880 and
885. Steps 880 and 885 may suitably executed independently of steps
of the steps of FIG. 8b.
[0153] The above operations of the processing circuit 815 cause the
supply flow module 632 to control both the heating coil 616 and the
supply flow damper 620 to regulate the temperature and fresh air
supply into the room 610. As discussed above, the processing
circuit 815 uses local RF communications to obtain the necessary
set points and other data to carry out the operations. In addition,
the processing circuit 815 communicates exhaust flow information to
the main exhaust module 624.
[0154] As referenced further above, FIGS. 9a and 9b show the
structure and operation of the main exhaust module 634. The main
exhaust control module 634 effectively controls the main exhaust
damper 624 to help regulate the removal of "spent" air that is
being replace with "fresh" air through the supply conduit 618. As
is known in the art, fresh air is preferably supplied to the room
610 even in the absence of noxious fumes or gas, particularly to
provide cooling air to maintain a steady temperature into the
room.
[0155] Referring now specifically to FIG. 9a, the main exhaust
module 634 has a general construction substantially similar to the
module 120 of FIGS. 12a and 12b. To this end, the main exhaust
module 634 includes an RF communication circuit 905, a power
management circuit 910, an processing circuit 915, an EEPROM 920,
and a sensor suite 925. Each of the elements of the main exhaust
module 634 operates generally as described above in connection with
FIGS. 12a and 12b.
[0156] The main exhaust module 634 includes a flow sensing
functionality, and is further configured to generate an actuator
output signal. The actuator output signal may suitably be provided
as analog output pin 915a on the processing circuit 915. The
actuator output signal is an analog output that controls the
operation of actuator for the damper 624. To this end, the analog
output pin 815a is connected to an external actuator 917, which in
turn controls the position of the damper 624.
[0157] To enable the flow sensing functionality, the EEPROM 920
includes configuration information identifying that the processing
circuit 915 should obtain an air flow measurement information from
the MEMS sensor suite 925. In the exemplary embodiment described
herein, the EEPROM 920 further includes sufficient program
instructions or code to carry out the operations illustrated in
FIG. 9b and described below.
[0158] The RF communication circuit 905 is preferably configured to
communicate with the other elements of the subsystem 114. As
discussed above, the RF communication circuit 905 may suitably be
configured to use Bluetooth or another local RF communication
protocol.
[0159] The operation of the main exhaust control module 634 is
described with reference to FIG. 9b, which shows an overview of the
functions of the processing circuit 915. As shown in FIG. 9b, in
step 950, the processing circuit 915 receives from time to time
(via the RF communication circuit 905) the main exhaust set point
W.sub.FLO, which is provided by the control module 630, as
discussed above.
[0160] In step 955, the processing circuit 915 receives a main
exhaust flow measurement X.sub.FLO. To this end, the processing
circuit 915 obtains an analog flow measurement value from the flow
sensor element within the MEMS sensor suite 925 and converts the
analog flow measurement value to a digital value representative
thereof X.sub.FLO.
[0161] In step 960, the processing circuit 915 calculates a main
exhaust damper control output Y.sub.FLO based on the measured flow
X.sub.FLO and the set point value W.sub.FLO. To this end, the
processing circuit 915 may use an ordinary PID algorithm.
[0162] In step 965, the processing circuit 915 provides an actuator
output signal corresponding to Y.sub.FLO to its output 915a, which
in turn provides the actuator output signal to the actuator 917.
The actuator 917 causes mechanical adjustment of the main exhaust
damper 624 responsive to the actuator output signal.
[0163] In step 970, the processing circuit 915 causes the RF
communication circuit 970 to communicate the measured flow value
X.sub.FLO to the control module 630.
[0164] The processing circuit 915 thereafter periodically receives
updates of its inputs and recalculates the actuator output signal.
In other words, steps 950-970 are periodically repeated.
[0165] The above operations of the processing circuit 915 operate
to control the main exhaust of "spent" air to the room based on the
set point W.sub.FLO generated by the control module 632. (See FIG.
8b). Alternative calculations of the exhaust flow set point
W.sub.FLO may be made. As discussed further above, in alternative
embodiments, the main exhaust flow may be adjusted to redirect air
flow through the fume hood exhaust dampers 626 and/or 628.
Regardless, one feature of this embodiment of the invention is that
balance between the supply flow and the main exhaust flow is
adjusted in response to a need to vent air or gas through the fume
hood exhausts.
[0166] FIGS. 10a and 10b show the structure and operation of the
first fume hood sensor module 640. The first fume hood sensor
module 640 effectively measures the concentration of one or more
select noxious gasses within the first fume hood 612. It will be
appreciated that the second fume hood sensor module 642 has a
substantially similar construction and operates in a substantially
similar way.
[0167] Referring now specifically to FIG. 10a, the first fume hood
sensor module 640 has a general construction substantially similar
to the module 1200 of FIGS. 12a and 12b. To this end, the first
fume hood sensor module 640 includes an RF communication circuit
1005, a power management circuit 1010, an processing circuit 1015,
an EEPROM 1020, and a sensor suite 1025. Each of the elements of
the first fume hood sensor module 640 operates generally as
described above in connection with FIGS. 12a and 12b.
[0168] The first fume hood sensor module 640 includes a gas
concentration sensing functionality. The gas may be any of a number
of noxious gasses. As discussed further above, various MEMS sensors
devices are known that detect the concentration of various gasses.
Thus, for example, the sensor suite 1025 may suitable include a
plurality of gas-specific sensors. To enable the gas sensing
functionality, the EEPROM 1020 includes configuration information
identifying that the processing circuit 1015 should obtain gas
concentration measurement information for one or more gasses from
the MEMS sensor suite 1025. It is noted that the gas sensing
functionality should correspond to the types of noxious gas or
gasses expected to be generated within the fume hood 612. With the
configurable EEPROM 1020, the module 640 may be reconfigured if the
type of noxious gas generated within the fume hood 612 changes.
[0169] In the alternative, the first fume hood sensor module 640
may include a MEMs-based gas chromatography element in the sensor
suite 1025. Such an element can provide gas chromatographic
information to the processing circuit 1015. The processing circuit
1015 may then analyze the information for specific gas content. The
EEPROM 1020 would provide configuration information as to which
gasses to monitor. A suitable MEMs-based gas chromatography device
is the "Lab on a Chip" available from Argon National Laboratories.
Others are known in the art.
[0170] In yet another embodiment, using gas chromatography or
similar gas content analysis, the configuration information of the
EEPROM 1020 may identify a template defining breathable air, for
example, having specific ranges of oxygen, nitrogen and carbon
dioxide. The processing circuit 1015 uses this template to
determine whether the oxygen, nitrogen and/or other breathable air
gasses are within predefined limits. If not, then X.sub.G1 would be
given a value that indicates the need for additional venting.
[0171] In any event, in the exemplary embodiment described herein,
the EEPROM 1020 further includes sufficient program instructions or
code to carry out the operations illustrated in FIG. 10b and
described below.
[0172] The RF communication circuit 1005 is preferably configured
to communicate with the other elements of the subsystem 114. As
discussed above, the RF communication circuit 1005 may suitably be
configured to use Bluetooth or another local RF communication
protocol.
[0173] The operation of the first fume hood sensor module 640 is
described with reference to FIG. 10b, which shows an overview of
the functions of the processing circuit 1015. With reference to
FIG. 10b, in step 1050, the processing circuit 1015 obtains a gas
concentration measurement value X.sub.G1. To this end, the
processing circuit 1015 obtains an analog gas concentration
measurement value from the gas concentration sensor element within
the MEMS sensor suite 1025 and converts the analog flow measurement
value to a digital value representative thereof, X.sub.G1.
[0174] In step 1055, the processing circuit 1015 provides the gas
concentration measurement value X.sub.G1 to the first fume hood
exhaust module 636 via the RF communication circuit 1005.
[0175] In embodiments in which the first fume hood sensor module
640 is cnfigured to obtain gas concentration measurements for a
plurality of different individual gasses, then steps 1050 and 1055
may be repeated for each gas.
[0176] The processing circuit 1015 thereafter periodically receives
updates of its inputs and recalculates the actuator output signal.
In other words, steps 1050 and 1055 are periodically repeated.
[0177] FIGS. 11a and 11b show the structure and operation of the
first fume hood exhaust module 636. The first fume hood exhaust
module 636 effectively controls the first fume hood exhaust damper
626 to help vent noxious gasses present within or in the vicinity
of the fume hood 612 out of the room 610. The need for venting is
based on the concentration measurement value X.sub.G1 generated by
the first fume hood sensor module 640, and a gas concentration set
point W.sub.G1.
[0178] It will be appreciated that the second fume hood exhaust
module 638 has a similar construction and operates in substantially
the same manner as the first fume hood exhaust module 636.
[0179] Referring now specifically to FIG. 11a, the first fume hood
exhaust module 636 has a general construction that is substantially
similar to the module 1200 of FIGS. 12a and 12b. To this end, the
first fume hood exhaust module 636 includes an RF communication
circuit 1105, a power management circuit 1110, an processing
circuit 1115, an EEPROM 1120, and a sensor suite 1125. Each of the
elements of the first fume hood exhaust module 636 operates
generally as described above in connection with FIGS. 12a and
12b.
[0180] The first fume hood exhaust module 636 includes a flow
sensing functionality, and is further configured to generate an
actuator output signal. The actuator output signal may suitably be
provided on analog output pin 1115a of the processing circuit 1115.
The actuator output signal is an analog output that controls the
operation of the actuator for the damper 626. To this end, the
analog output pin 1115a is connected to an external actuator 1117,
which in turn controls the position of the damper 626.
[0181] To enable the flow sensing functionality, the EEPROM 1120
includes configuration information identifying that the processing
circuit 1115 should obtain an air flow measurement information from
the MEMS sensor suite 1125. The EEPROM 1120 also includes
information identifying the tolerable limits for concentration of
the gas, or in other words, the gas concentration set point
W.sub.G1 for the gas x being measured in the first fume hood 612.
In the exemplary embodiment described herein, the EEPROM 720
further includes sufficient program instructions or code to carry
out the operations illustrated in FIG. 11b and described below.
[0182] The RF communication circuit 1105 is preferably configured
to communicate with the other elements of the subsystem 114 using a
local RF communication protocol.
[0183] The operation of the first fume hood exhaust module 636 is
described with reference to FIG. 11b, which shows an overview of
the functions of the processing circuit 1115. With reference to
FIG. 11b, in step 1150, the processing circuit 1115 receives from
time to time (via the RF communication circuit 1105) the gas
concentration measurement value X.sub.G1, which is provided by the
first fume hood sensor module 640, as discussed above.
[0184] In step 1155, the processing circuit 1115 calculates a first
gas concentration control output Y.sub.G1 based on the measured gas
concentration value X.sub.G1 and the gas concentration set point
W.sub.G1. To this end, the processing circuit 1115 may use an
ordinary PID algorithm, the configuration of which would be known
to those of ordinary skill in the art.
[0185] In step 1160, the processing circuit 1115 then determines a
set point value for the first fume hood exhaust flow, W.sub.G1FL,
based on the gas concentration control output Y.sub.G1. To this
end, the processing circuit 1115 may simply set
W.sub.G1FL=Y.sub.G1, if scaling or other adjustments for unit
conversion are not required.
[0186] In step 1165, the processing circuit 1115 receives a first
fume hood exhaust flow measurement X.sub.G1FL. To this end, the
processing circuit 1115 obtains an analog flow measurement value
from the flow sensor element within the MEMS sensor suite 1125 and
converts the analog flow measurement value to a digital value
representative thereof, X.sub.G1FL.
[0187] In step 1170, the processing circuit 1115 calculates a first
fume hood exhaust damper control output Y.sub.G1FL based on the
measured flow X.sub.G1FL and the set point value W.sub.G1FL. Again,
the processing circuit 1115 may use an ordinary PID algorithm to
perform the calculation.
[0188] In step 1175, the processing circuit 1115 provides an
actuator output signal corresponding to Y.sub.G1FL to its output
1115a, which in turn provides to the actuator 1117 that causes
mechanical adjustment of the first fume hood exhaust damper
626.
[0189] As with the processing circuit 715 of FIG. 7a, the
processing circuit 1115 thereafter periodically receives updates of
its inputs and recalculates the actuator output signal. In other
words, steps 1150-1175, although not necessarily in strict order.
The processing circuit 1115 also communicates the set point
W.sub.G1FL to the control module 630.
[0190] The above operations of the processing circuit 1115 operate
to control the venting of gas-laden air through control of the
damper 626. The processing circuit 1115 controls the venting based
on the measured gas concentration X.sub.G1 received periodically
from the first fume hood sensor module 640 and the desired gas
concentration set point W.sub.G1 stored in the EEPROM 1120. It is
noted that the value of W.sub.G1 may be programmed into the EEPROM
1120 upon configuration of the module 636, or may be received from
supervisory devices external to the subsystem 114 via the control
module 630. It will also be noted, the control calculation of step
1155 may be carried out in the first fume hood sensor module
640.
[0191] One of the advantages of incorporating wireless MEMS modules
in a building subsystem or system that includes fume hoods is the
reduced wiring requirements over normal fume hood systems.
Moreover, by detecting the relative presence of noxious gasses
within the fume hood, the fume hood is only vented when noxious
gasses are present, or in other words, only as needed. The
arrangement thus potentially conserves energy by ventilating only
to the extent necessary. It is noted that the fume hood sensor
module 640 and/or the fume hood exhaust module 636 may be
programmed to detect an alarm condition and provide a wireless (or
wire output pin) signal to a visible and/or audible alarm device,
not shown.
[0192] It will be appreciated that the above described embodiments
are merely illustrative, and that those of ordinary skill in the
art may readily devise their own adaptations and implementations
that incorporate the principles of the present invention and fall
within the spirit and scope thereof. For example, control systems
or subsystems having any number of fume hoods may be adapted to
incorporate the principles of the present invention.
[0193] Moreover implementation of the subsystems incorporating
features from either or both of subsystems 110 and 114 may be used
in building control systems that are not completely wireless. The
space control subsystems 110 of FIG. 2 may readily be modified for
use in a conventional wired building control system. To this end,
my copending application, Attorney Docket No. 2002 P 01349 US 01,
entitled "Building System With Reduced Wiring Requirements and
Apparatus for Use Therein", filed on even date herewith and which
is incorporated herein by reference, describes a suitable method
for incorporating individual subsystems into current building
automation system architecture.
* * * * *
References