U.S. patent application number 13/006463 was filed with the patent office on 2011-07-21 for integrated part temperature measurement system.
This patent application is currently assigned to FARO TECHNOLOGIES, INC.. Invention is credited to Paul C. Atwell, Clark H. Briggs, Orlando Perez.
Application Number | 20110178758 13/006463 |
Document ID | / |
Family ID | 43736091 |
Filed Date | 2011-07-21 |
United States Patent
Application |
20110178758 |
Kind Code |
A1 |
Atwell; Paul C. ; et
al. |
July 21, 2011 |
INTEGRATED PART TEMPERATURE MEASUREMENT SYSTEM
Abstract
Exemplary embodiments include a portable articulated arm
coordinate measurement machine, including a manually positionable
articulated arm having opposed first and second ends, the arm
including a plurality of connected arm segments, each of the arm
segments including at least one position transducer for producing a
position signal, a measurement device attached to a first end of
the articulated arm coordinate measurement machine, an electronic
circuit for receiving the position signals from the transducers and
for providing data corresponding to a position of the measurement
device, at least one sensor element, which is disposed on the
articulated arm coordinate measurement machine, that is responsive
to electromagnetic radiation and produces an electrical signal in
response to a temperature of an object and an electronic system
that converts the electrical signal into a temperature value.
Inventors: |
Atwell; Paul C.; (Lake Mary,
FL) ; Briggs; Clark H.; (DeLand, FL) ; Perez;
Orlando; (Lake Mary, FL) |
Assignee: |
FARO TECHNOLOGIES, INC.
Lake Mary
FL
|
Family ID: |
43736091 |
Appl. No.: |
13/006463 |
Filed: |
January 14, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61296555 |
Jan 20, 2010 |
|
|
|
Current U.S.
Class: |
702/134 ;
702/150 |
Current CPC
Class: |
G05B 19/401 20130101;
G05B 19/406 20130101; G05B 2219/40596 20130101; G01B 21/047
20130101; G01B 11/007 20130101; G01B 5/012 20130101; G05B
2219/45061 20130101; G05B 2219/24067 20130101; G05B 2219/37193
20130101; G05B 2219/40233 20130101 |
Class at
Publication: |
702/134 ;
702/150 |
International
Class: |
G06F 15/00 20060101
G06F015/00 |
Claims
1. A portable articulated arm coordinate measurement machine
(AACMM), comprising: a manually positionable articulated arm having
opposed first and second ends, the arm including a plurality of
connected arm segments, each of the arm segments including at least
one position transducer for producing a position signal; a
measurement device attached to a first end of the AACMM; an
electronic circuit for receiving the position signals from the
transducers and for providing data corresponding to a position of
the measurement device; at least one sensor element, which is
disposed on the AACMM, that is responsive to electromagnetic
radiation and produces an electrical signal in response to a
temperature of an object; and an electronic system that converts
the electrical signal into a temperature value.
2. The AACMM as claimed in claim 1 wherein the electronic circuit
is configured to display the temperature value.
3. The AACMM as claimed in claim 2 further comprising a user
interface configured to display a plurality of temperature values
in a plot.
4. The AACMM as claimed in claim 1 further comprising a processor
configured to associate the temperature value with a coordinate of
the object.
5. The AACMM as claimed in claim 4 wherein the processor is further
configured to use coordinates of at least three points measured by
the measurement device.
6. The AACMM as claimed in claim 5 wherein the processor is further
configured to overlay a CAD model onto the at least three
points.
7. The AACMM as claimed in claim 5 wherein the processor is further
configured to overlay a given geometrical shape onto the at least
three points.
8. The AACMM as claimed in claim 3 wherein the processor is further
configured to plot the plurality of temperature values as a
function of position on the object.
9. The AACMM as claimed in claim 8, wherein the processor is
further configured to plot the plurality of temperature values onto
a three-dimensional representation of the object.
10. The AACMM as claimed in claim 9, wherein the processor is
further configured to represent the temperature values with gray
scale, colors, contours, or whiskers.
11. A method of implementing a portable articulated arm coordinate
measuring machine (AACMM), the method comprising: measuring a
temperature value of an object with an integrated temperature
measurement system disposed on the portable AACMM, wherein the
integrated temperature measurement system is responsive to
electromagnetic radiation that varies with the temperature of the
object, the portable AACMM comprised of a manually positionable
articulated arm having opposed first and second ends, the arm
including a plurality of connected arm segments, each arm segment
including at least one position transducer for producing a position
signal, a measurement device attached to a first end of the AACMM,
and an electronic circuit which receives the position signals from
the transducers and provides data corresponding to a position of
the measurement device; receiving the temperature value in the
electronic circuit; and displaying the temperature value on a user
interface.
12. The method as claimed in claim 11 wherein the user interface is
disposed on the AACMM.
13. The method as claimed in claim 11 wherein the user interface
displays a plurality of temperature values in a plot.
14. The method as claimed in claim 13 wherein the plot displays at
least one of a temperature gradient and a critical temperature of
the object.
15. The method as claimed in claim 13 wherein the temperature
values are processed to determine if there is at least one of a
critical temperature and a critical expansion of the object.
16. The method as claimed in claim 13 wherein the plot indicates
the magnitude of dimensional changes resulting from changes in the
temperatures of the object relative to a reference temperature.
17. A computer program product for implementing a portable
articulated arm coordinate measuring machine (AACMM), the computer
program product comprising a storage medium having
computer-readable program code embodied thereon, which when
executed by a computer causes the computer to implement a method,
the method including: measuring a temperature value of an object
with an integrated temperature measurement system disposed on the
portable AACMM, wherein the integrated temperature measurement
system is responsive to electromagnetic radiation that varies with
the temperature of the object, the portable AACMM comprised of a
manually positionable articulated arm having opposed first and
second ends, the arm including a plurality of connected arm
segments, each arm segment including at least one position
transducer for producing a position signal, a measurement device
attached to a first end of the AACMM, and an electronic circuit
which receives the position signals from the transducers and
provides data corresponding to a position of the measurement
device; receiving the temperature value in the electronic circuit;
and displaying the temperature value on a user interface.
18. A computer program product as claimed in claim 17 wherein the
user interface is disposed on the AACMM.
19. The computer program product as claimed in claim 17 wherein the
user interface displays a plurality of temperature values in a
plot.
20. The computer program product as claimed in claim 19 wherein the
plot displays at least one of a temperature gradient and a critical
temperature of the object.
21. The computer program product as claimed in claim 19 wherein the
temperature values are processed to determine if there is at least
one of a critical temperature and a critical expansion of the
object.
22. The computer program product as claimed in claim 19 wherein the
plot indicates the magnitude of dimensional changes resulting from
changes in the temperatures of the object relative to a reference
temperature.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of provisional
application No. 61/296,555 filed Jan. 20, 2010, the content of
which is hereby incorporated by reference in its entirety.
BACKGROUND
[0002] The present disclosure relates to a coordinate measuring
machine, and more particularly to a portable articulated arm
coordinate measuring machine having an integrated part temperature
measurement system configured to measure the temperature of
objects.
[0003] Portable articulated arm coordinate measuring machines
(AACMMs) have found widespread use in the manufacturing or
production of parts where there is a need to rapidly and accurately
verify the dimensions of the part during various stages of the
manufacturing or production (e.g., machining) of the part. Portable
AACMMs represent a vast improvement over known stationary or fixed,
cost-intensive and relatively difficult to use measurement
installations, particularly in the amount of time it takes to
perform dimensional measurements of relatively complex parts.
Typically, a user of a portable AACMM simply guides a probe along
the surface of the part or object to be measured. The measurement
data are then recorded and provided to the user. In some cases, the
data are provided to the user in visual form, for example,
three-dimensional (3-D) form on a computer screen. In other cases,
the data are provided to the user in numeric form, for example when
measuring the diameter of a hole, the text "Diameter=1.0034" is
displayed on a computer screen.
[0004] An example of a prior art portable articulated arm CMM is
disclosed in commonly assigned U.S. Pat. No. 5,402,582 ('582),
which is incorporated herein by reference in its entirety. The '582
patent discloses a 3-D measuring system comprised of a
manually-operated articulated arm CMM having a support base on one
end and a measurement probe at the other end. Commonly assigned
U.S. Pat. No. 5,611,147 ('147), which is incorporated herein by
reference in its entirety, discloses a similar articulated arm CMM.
In the '147 patent, the articulated arm CMM includes a number of
features including an additional rotational axis at the probe end,
thereby providing for an arm with either a two-two-two or a
two-two-three axis configuration (the latter case being a seven
axis arm).
[0005] What is needed is an apparatus and a method that can measure
the temperatures of an object and the coordinates corresponding to
those temperatures.
SUMMARY OF THE INVENTION
[0006] Exemplary embodiments include a portable articulated arm
coordinate measurement machine, including a manually positionable
articulated arm having opposed first and second ends, the arm
including a plurality of connected arm segments, each of the arm
segments including at least one position transducer for producing a
position signal, a measurement device attached to a first end of
the articulated arm coordinate measurement machine, an electronic
circuit for receiving the position signals from the transducers and
for providing data corresponding to a position of the measurement
device, at least one sensor element, which is disposed on the
articulated arm coordinate measurement machine, that is responsive
to electromagnetic radiation and produces an electrical signal in
response to a temperature of an object and an electronic system
that converts the electrical signal into a temperature value.
[0007] Additional exemplary embodiments include a method of
implementing a portable articulated arm coordinate measuring
machine, the method including measuring a temperature value of an
object with an integrated temperature measurement system disposed
on the portable articulated arm coordinate measuring machine,
wherein the integrated temperature measurement system is responsive
to electromagnetic radiation that varies with the temperature of
the object, the portable articulated arm coordinate measuring
machine comprised of a manually positionable articulated arm having
opposed first and second ends, the arm including a plurality of
connected arm segments, each arm segment including at least one
position transducer for producing a position signal, a measurement
device attached to a first end of the articulated arm coordinate
measuring machine, and an electronic circuit which receives the
position signals from the transducers and provides data
corresponding to a position of the measurement device, receiving
the temperature value in the electronic circuit and displaying the
temperature value on a user interface.
[0008] Further exemplary embodiments include a computer program
product for implementing a portable articulated arm coordinate
measuring machine, the computer program product comprising a
storage medium having computer-readable program code embodied
thereon, which when executed by a computer causes the computer to
implement a method, the method including measuring a temperature
value of an object with an integrated temperature measurement
system disposed on the portable articulated arm coordinate
measuring machine, wherein the integrated temperature measurement
system is responsive to electromagnetic radiation that varies with
the temperature of the object, the portable articulated arm
coordinate measuring machine comprised of a manually positionable
articulated arm having opposed first and second ends, the arm
including a plurality of connected arm segments, each arm segment
including at least one position transducer for producing a position
signal, a measurement device attached to a first end of the
articulated arm coordinate measuring machine, and an electronic
circuit which receives the position signals from the transducers
and provides data corresponding to a position of the measurement
device, receiving the temperature value in the electronic circuit
and displaying the temperature value on a user interface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Referring now to the drawings, exemplary embodiments are
shown which should not be construed to be limiting regarding the
entire scope of the disclosure, and wherein the elements are
numbered alike in several FIGURES:
[0010] FIG. 1, including FIGS. 1A and 1B, are perspective views of
a portable articulated arm coordinate measuring machine (AACMM)
having embodiments of various aspects of the present invention
therewithin;
[0011] FIG. 2, including FIGS. 2A-2D taken together, is a block
diagram of electronics utilized as part of the AACMM of FIG. 1 in
accordance with an embodiment;
[0012] FIG. 3, including FIGS. 3A and 3B taken together, is a block
diagram describing detailed features of the electronic data
processing system of FIG. 2 in accordance with an embodiment;
[0013] FIG. 4 illustrates a screenshot of an exemplary graphical
user interface in which an operator can detect temperature and
changes in temperature in an object measured by the AACMM; and
[0014] FIG. 5 is a flowchart of a method for measuring temperature
in accordance with exemplary embodiments.
DETAILED DESCRIPTION
[0015] Exemplary embodiments include systems and methods for
measuring with an articulated arm coordinate measurement machine
(AACMM) the temperature of an object as a function of position on
the object and providing the temperature data to an operator. In
some embodiments, the AACMM or software associated with the AACMM
provides the operator with visual information about the
temperature. It may also provide an audio or visual alarm or alert.
In other embodiments, the temperature information is used to
correct dimensional measurements taken by the AACMM. To make such
corrections, the user of the AACMM provides information about the
coefficient of thermal expansion (CTE) of the material being
measured. Frequently, specifications recite dimensions at a
standard temperature, usually 20.degree. C., while the object being
measured is at another temperature. By knowing the object
temperature and the CTE, the measured dimensions can be normalized
to the standard temperature. The systems and methods described
herein may also be used to check whether the object is in thermal
equilibrium (e.g., a part may have been recently machined, welded,
or moved from outside and may not be at a uniform temperature). As
such, the systems and methods described herein determine whether
dimensional measurements are valid.
[0016] In addition, temperature measurement may be used as an end
in itself. In exemplary embodiments, the systems and methods
described herein can map the temperature of an object in 3-D. For
example, a user may want to map the temperature of the surface of a
diesel engine under normal and 110% of full load conditions. As
another example, a user may want to map the temperature of
electrical components loaded on a printed circuit board, as well as
the temperature of the mechanical structure to which the printed
circuit board is attached. Such measurements can be used to
determine whether additional heat sinking is needed for particular
electrical components, for example. It might also be used as part
of a finite element model to assist engineers in verifying or
improving their designs.
[0017] FIGS. 1A and 1B illustrate, in perspective, a portable
articulated arm coordinate measuring machine (AACMM) 100 according
to various embodiments of the present invention, an articulated arm
being one type of coordinate measuring machine. As shown in FIGS.
1A and 1B, the exemplary AACMM 100 may comprise a six or seven axis
articulated measurement device having a measurement probe housing
102 coupled to an arm portion 104 of the AACMM 100 at one end. The
arm portion 104 comprises a first arm segment 106 coupled to a
second arm segment 108 by a first grouping of bearing cartridges
110 (e.g., two bearing cartridges). A second grouping of bearing
cartridges 112 (e.g., two bearing cartridges) couples the second
arm segment 108 to the measurement probe housing 102. A third
grouping of bearing cartridges 114 (e.g., three bearing cartridges)
couples the first arm segment 106 to a base 116 located at the
other end of the arm portion 104 of the AACMM 100. Each grouping of
bearing cartridges 110, 112, 114 provides for multiple axes of
articulated movement. Also, the measurement probe housing 102 may
comprise the shaft of the seventh axis portion of the AACMM 100
(e.g., a cartridge containing an encoder system that determines
movement of the measurement device, for example a probe 118, in the
seventh axis of the AACMM 100). In use of the AACMM 100, the base
116 is typically affixed to a work surface.
[0018] Each bearing cartridge within each bearing cartridge
grouping 110, 112, 114 typically contains an encoder system (e.g.,
an optical angular encoder system). The encoder system (i.e.,
transducer) provides an indication of the position of the
respective arm segments 106, 108 and corresponding bearing
cartridge groupings 110, 112, 114 that all together provide an
indication of the position of the probe 118 with respect to the
base 116 (and, thus, the position of the object being measured by
the AACMM 100 in a certain frame of reference--for example a local
or global frame of reference). The arm segments 106, 108 may be
made from a suitably rigid material such as but not limited to a
carbon composite material for example. A portable AACMM 100 with
six or seven axes of articulated movement (i.e., degrees of
freedom) provides advantages in allowing the operator to position
the probe 118 in a desired location within a 360.degree. area about
the base 116 while providing an arm portion 104 that may be easily
handled by the operator. However, it should be appreciated that the
illustration of an arm portion 104 having two arm segments 106, 108
is for exemplary purposes, and the claimed invention should not be
so limited. An AACMM 100 may have any number of arm segments
coupled together by bearing cartridges (and, thus, more or less
than six or seven axes of articulated movement or degrees of
freedom).
[0019] The probe 118 is detachably mounted to the measurement probe
housing 102, which is connected to bearing cartridge grouping 112.
A handle 126 is removable with respect to the measurement probe
housing 102 by way of, for example, a quick-connect interface. The
handle 126 may be replaced with another device (e.g., a laser line
probe, a bar code reader), thereby providing advantages in allowing
the operator to use different measurement devices with the same
AACMM 100. In exemplary embodiments, the probe housing 102 houses a
removable probe 118, which is a contacting measurement device and
may have different tips 118 that physically contact the object to
be measured, including, but not limited to: ball, touch-sensitive,
curved and extension type probes. In other embodiments, the
measurement is performed, for example, by a non-contacting device
such as a laser line probe (LLP). In an embodiment, the handle 126
is replaced with the LLP using the quick-connect interface. Other
types of measurement devices may replace the removable handle 126
to provide additional functionality. Examples of such measurement
devices include, but are not limited to, one or more illumination
lights, a temperature sensor, a thermal scanner, a bar code
scanner, a projector, a paint sprayer, a camera, or the like, for
example.
[0020] As shown in FIGS. 1A and 1B, the AACMM 100 includes the
removable handle 126 that provides advantages in allowing
accessories or functionality to be changed without removing the
measurement probe housing 102 from the bearing cartridge grouping
112. As discussed in more detail below with respect to FIG. 2, the
removable handle 126 may also include an electrical connector that
allows electrical power and data to be exchanged with the handle
126 and the corresponding electronics located in the probe end.
[0021] In various embodiments, each grouping of bearing cartridges
110, 112, 114 allows the arm portion 104 of the AACMM 100 to move
about multiple axes of rotation. As mentioned, each bearing
cartridge grouping 110, 112, 114 includes corresponding encoder
systems, such as optical angular encoders for example, that are
each arranged coaxially with the corresponding axis of rotation of,
e.g., the arm segments 106, 108. The optical encoder system detects
rotational (swivel) or transverse (hinge) movement of, e.g., each
one of the arm segments 106, 108 about the corresponding axis and
transmits a signal to an electronic data processing system within
the AACMM 100 as described in more detail herein below. Each
individual raw encoder count is sent separately to the electronic
data processing system as a signal where it is further processed
into measurement data. No position calculator separate from the
AACMM 100 itself (e.g., a serial box) is required, as disclosed in
commonly assigned U.S. Pat. No. 5,402,582 ('582).
[0022] The base 116 may include an attachment device or mounting
device 120. The mounting device 120 allows the AACMM 100 to be
removably mounted to a desired location, such as an inspection
table, a machining center, a wall or the floor for example. In one
embodiment, the base 116 includes a handle portion 122 that
provides a convenient location for the operator to hold the base
116 as the AACMM 100 is being moved. In one embodiment, the base
116 further includes a movable cover portion 124 that folds down to
reveal a user interface, such as a display screen.
[0023] In accordance with an embodiment, the base 116 of the
portable AACMM 100 contains or houses an electronic data processing
system that includes two primary components: a base processing
system that processes the data from the various encoder systems
within the AACMM 100 as well as data representing other arm
parameters to support three-dimensional (3-D) positional
calculations; and a user interface processing system that includes
an on-board operating system, a touch screen display, and resident
application software that allows for relatively complete metrology
functions to be implemented within the AACMM 100 without the need
for connection to an external computer.
[0024] The electronic data processing system in the base 116 may
communicate with the encoder systems, sensors, and other peripheral
hardware located away from the base 116 (e.g., a LLP that can be
mounted to the removable handle 126 on the AACMM 100). The
electronics that support these peripheral hardware devices or
features may be located in each of the bearing cartridge groupings
110, 112, 114 located within the portable AACMM 100.
[0025] FIG. 2 is a block diagram of electronics utilized in an
AACMM 100 in accordance with an embodiment. The embodiment shown in
FIG. 2 includes an electronic data processing system 210 including
a base processor board 204 for implementing the base processing
system, a user interface board 202, a base power board 206 for
providing power, a Bluetooth module 232, and a base tilt board 208.
The user interface board 202 includes a computer processor for
executing application software to perform user interface, display,
and other functions described herein.
[0026] As shown in FIG. 2, the electronic data processing system
210 is in communication with the aforementioned plurality of
encoder systems via one or more arm buses 218. In the embodiment
depicted in FIG. 2, each encoder system generates encoder data and
includes: an encoder arm bus interface 214, an encoder digital
signal processor (DSP) 216, an encoder read head interface 234, and
a temperature sensor 212. Other devices, such as strain sensors,
may be attached to the arm bus 218.
[0027] Also shown in FIG. 2 are probe end electronics 230 that are
in communication with the arm bus 218. The probe end electronics
230 include a probe end DSP 228, a temperature sensor 212, a
handle/LLP interface bus 240 that connects with the handle 126 or
the LLP 242 via the quick-connect interface in an embodiment, and a
probe interface 226. The quick-connect interface allows access by
the handle 126 to the data bus, control lines, and power bus used
by the LLP 242 and other accessories. In an embodiment, the probe
end electronics 230 are located in the measurement probe housing
102 on the AACMM 100. In an embodiment, the handle 126 may be
removed from the quick-connect interface and measurement may be
performed by the laser line probe (LLP) 242 communicating with the
probe end electronics 230 of the AACMM 100 via the handle/LLP
interface bus 240. In an embodiment, the electronic data processing
system 210 is located in the base 116 of the AACMM 100, the probe
end electronics 230 are located in the measurement probe housing
102 of the AACMM 100, and the encoder systems are located in the
bearing cartridge groupings 110, 112, 114. The probe interface 226
may connect with the probe end DSP 228 by any suitable
communications protocol, including commercially-available products
from Maxim Integrated Products, Inc. that embody the 1-wire.RTM.
communications protocol 236.
[0028] FIG. 3 is a block diagram describing detailed features of
the electronic data processing system 210 of the AACMM 100 in
accordance with an embodiment. In an embodiment, the electronic
data processing system 210 is located in the base 116 of the AACMM
100 and includes the base processor board 204, the user interface
board 202, a base power board 206, a Bluetooth module 232, and a
base tilt module 208.
[0029] In an embodiment shown in FIG. 3, the base processor board
204 includes the various functional blocks illustrated therein. For
example, a base processor function 302 is utilized to support the
collection of measurement data from the AACMM 100 and receives raw
arm data (e.g., encoder system data) via the arm bus 218 and a bus
control module function 308. The memory function 304 stores
programs and static arm configuration data. The base processor
board 204 also includes an external hardware option port function
310 for communicating with any external hardware devices or
accessories such as an LLP 242. A real time clock (RTC) and log
306, a battery pack interface (IF) 316, and a diagnostic port 318
are also included in the functionality in an embodiment of the base
processor board 204 depicted in FIG. 3.
[0030] The base processor board 204 also manages all the wired and
wireless data communication with external (host computer) and
internal (display processor 202) devices. The base processor board
204 has the capability of communicating with an Ethernet network
via an Ethernet function 320 (e.g., using a clock synchronization
standard such as Institute of Electrical and Electronics Engineers
(IEEE) 1588), with a wireless local area network (WLAN) via a LAN
function 322, and with Bluetooth module 232 via a parallel to
serial communications (PSC) function 314. The base processor board
204 also includes a connection to a universal serial bus (USB)
device 312.
[0031] The base processor board 204 transmits and collects raw
measurement data (e.g., encoder system counts, temperature
readings) for processing into measurement data without the need for
any preprocessing, such as disclosed in the serial box of the
aforementioned '582 patent. The base processor 204 sends the
processed data to the display processor 328 on the user interface
board 202 via an RS485 interface (IF) 326. In an embodiment, the
base processor 204 also sends the raw measurement data to an
external computer.
[0032] Turning now to the user interface board 202 in FIG. 3, the
angle and positional data received by the base processor is
utilized by applications executing on the display processor 328 to
provide an autonomous metrology system within the AACMM 100.
Applications may be executed on the display processor 328 to
support functions such as, but not limited to: measurement of
features, guidance and training graphics, remote diagnostics,
temperature corrections, control of various operational features,
connection to various networks, and display of measured objects.
Along with the display processor 328 and a liquid crystal display
(LCD) 338 (e.g., a touch screen LCD) user interface, the user
interface board 202 includes several interface options including a
secure digital (SD) card interface 330, a memory 332, a USB Host
interface 334, a diagnostic port 336, a camera port 340, an
audio/video interface 342, a dial-up/cell modem 344 and a global
positioning system (GPS) port 346.
[0033] The electronic data processing system 210 shown in FIG. 3
also includes a base power board 206 with an environmental recorder
362 for recording environmental data. The base power board 206 also
provides power to the electronic data processing system 210 using a
DC/DC converter 358 and a battery charger control 360. The base
power board 206 communicates with the base processor board 204
using inter-integrated circuit (12C) serial single ended bus 354 as
well as via a device service provider interface (DSPI) 356. The
base power board 206 is connected to a tilt sensor and radio
frequency identification (RFID) module 208 via an input/output
(I/O) expansion function 364 implemented in the base power board
206.
[0034] Though shown as separate components, in other embodiments
all or a subset of the components may be physically located in
different locations and/or functions combined in different manners
than that shown in FIG. 3. For example, in one embodiment, the base
processor board 204 and the user interface board 202 are combined
into one physical board.
[0035] Referring to FIG. 4, another aspect of the improvements to
the portable AACMM 100 of embodiments of the present invention
includes the incorporation of a part temperature measurement and/or
profiling system within the AACMM 100. In this aspect of the
present invention, the temperature of the part being measured may
be captured, integrated with the arm data stream, and provided to
the metrology application software. This temperature may be used in
correcting for dimensional changes due to the coefficient of
thermal expansion of the part material. Alternatively, it may be
used to provide accurate temperature data as a function of position
on the object, thereby enabling the temperature profile to be
accurately mapped onto a computer-aided design (CAD) model. The
temperature profile 440 may be displayed, as illustrated in FIG. 4.
The temperature profile 440 can include a numeric readout 410 or
other graphical interface, displaying the numeric temperature of
the object(s) under test. The temperature profile 440 can further
include a color or gray scale plot 420 of temperature distribution
in the object(s) under test. The plot 420 can therefore visually
display temperature gradients and critical temperatures of objects
under test.
[0036] In this context, a critical temperature is a temperature of
an object that exceeds some allowable deviation from a reference
temperature value. For example, if the dimensions of a particular
object are specified at 20.degree. C., then the allowable range of
temperatures for measurement by the AACMM in a particular instance
might be 17-23.degree. C. Outside of this value, the operator might
be instructed to attach a contact temperature sensor, such as a
thermistor, directly to the object so that temperature can be
measured and corrections made numerically to account for thermal
expansion or contraction. Similarly, it would be possible to
specify a critical expansion, for example in parts per million or
micrometers. The critical expansion of the object would then be an
expansion or contraction of the material considered excessive by
the user. Outside of the acceptable range, the user might be
instructed to attach a contact temperature sensor to the
object.
[0037] The temperature may be displayed directly on a
three-dimensional representation of the object being measured.
Modern application software provides the ability to rotate a
three-dimensional representation of an object on a display. Such a
display might be a CAD model of the object, or it might be a
representation of the object as measured by the AACMM 100.
Measurements by the AACMM might be carried out with probe 118 that
makes direct contact with an object or with non-contact devices
such as a laser line probe or with a combination of contact and
non-contact measurement devices. The temperature can be displayed
on such three-dimensional representation in a variety of ways. For
example, temperature can be represented by gray scale, by color, by
a contour map, or by "whiskers." Whiskers are small projections
having a length proportional to the deviation from a reference
temperature.
[0038] Similarly, thermal expansion or contraction relative to
dimensions at a reference temperature can be directly mapped onto a
three-dimensional representation of the object. For example, such a
contraction might be given in terms of a relative change delta L/L,
where delta L is the change in some small length at a local
position and L is value of the small length. Such a measure is
dimensionless and may also be given in parts per million (ppm). The
quantity delta L/L can be found by multiplying the CTE of the
object times the deviation of temperature from a reference value.
Alternatively, thermal expansion might be represented in absolute
terms using the actual change in length in micrometers or
millimeters relative to some datum features such as datum planes or
datum points. Graphical representations of thermal expansion or
contraction, whether given in relative or absolute terms, may be
shown using color, contour maps, or whiskers, for example.
[0039] Measurement of the temperatures or thermal expansions of
objects over their three-dimensional coordinates is useful in a
variety of ways. As discussed already, such measurements can alert
the user that temperatures or thermal expansions or contractions
are outside an acceptable range so that corrective action may be
taken. In other cases, the temperature profile of an object may be
of interest in its own right.
[0040] The software may also use temperature values provided by an
exemplary temperature measurement system to directly correct or
normalize the measured dimensional values to a reference
temperature. The user might enter information on the CTE of the
material(s) being measured into the user interface to enable this
correction to take place automatically.
[0041] Exemplary embodiments of the temperature measurement system
may include an integrated infrared or other non-contact temperature
sensor in the handle 126 or in an accessory (e.g., laser line
probe) attached to the arm portion 104 of the AACMM 100, and/or a
means to connect a contact, or non-contact, remote temperature
sensor (via a connector, Bluetooth, Wi-Fi or other protocols) to
the AACMM electronics. Also included may be interface electronics
to power, read and/or control the temperature measurement hardware,
and firmware and/or software to format the temperature data and
pass it via the arm data communication stream to the application
software running internal to the AACMM 100 or on an external
computer. Further included may be switches, or software controls to
initiate and control parameters of the temperature measurement, and
a user interface, integrated with the AACMM 100 or on an external
computer to display temperature data and control options.
[0042] The non-contact temperature measurement system may be made
using sensors that respond to electromagnetic energy. Such sensors
are often called infrared sensors although visible wavelengths as
well as infrared wavelengths may be important, especially for hot
materials. Such sensors that respond to electromagnetic energy come
in a variety of types. For example, an infrared sensor may be a
single detector (usually sensitive over some range of infrared
wavelengths) or it may include an array of optical detectors. FIG.
4 shows an example of data taken with an array of optical
detectors, with the temperature at each particular point indicated
by a gray scale value.
[0043] Some infrared sensors measure the amount of electromagnetic
energy detected over a relatively narrow range of optical
wavelengths. The temperature at any particular point can be found
from the detected energy if the emissivity of the material is
known. Other types of infrared sensors measure the amount of
electromagnetic energy over two relatively narrow ranges of optical
wavelengths. The two energies can be used to estimate the
temperature of the material when the emissivity of the material is
not known. Another method for measuring the temperature of a
material when emissivity of the material is not known is to put a
reference object having a known emissivity (e.g., a black disk)
into close thermal contact with the object under test. By measuring
the energy returned by the reference object, the temperature of the
object under test can be obtained. A method for finding the
emissivity of a material is to measure the temperature of the
object under test in the vicinity of the reference object. From the
collected data, the emissivity of the object under test can be
estimated.
[0044] A non-contact temperature sensor that responds to
electromagnetic energy converts the electromagnetic energy or power
into an electrical signal. This signal may be amplified, filtered,
or conditioned in other ways. Such conditioning may take place
close to the sensor or it may be performed at some distance from
the sensor. The signal may be converted from analog into digital
form for transmission over an electrical wire or an electrical bus,
or it may be transmitted wirelessly. Alternatively, the electrical
signal may be transmitted some distance in analog form. The
digitally converted signal may be analyzed with a processor or
other device through the use of equations, for example, equations
based on the Planck's law, to find the temperature of the object
based on a given emissivity. Alternatively, other methods such as
the two color method described above may be evaluated using a
processor with appropriate equations based on Planck's law, for
example. Because the conversion of the electromagnetic signal
received by the sensor element may be electrically processed in a
variety of ways and because such processing may be carried out at
different locations, either inside or outside the AACMM 100, we may
say that an electrical system is used to convert the electrical
signal from the sensor element into a temperature value. If a
plurality of sensor elements is used, the electrical system is used
to convert the plurality of electrical signals obtained from these
into a plurality of temperatures. Additional processing elements
contained within an electrical circuit are used to provide the
temperature information to a display. Such a display may be
integrated within the AACMM 100 or outside of the AACMM 100 (for
example, an external computer).
[0045] FIG. 5 is a flowchart of a method 500 for measuring
temperature in accordance with exemplary embodiments illustrating
that the AACMM 100 can continuously measure temperature at block
510 and display the measurements at block 520 continuously for so
long as the operator elects to measure and display at block
530.
[0046] Using AACMM 100 with a temperature measurement system is
advantageous because it enables the temperatures to be directly
related to coordinates of the object under test. Furthermore, the
AACMM 100 may be moved to different locations to view the object
from all directions. Yet, because the dimensional information
collected by the AACMM 100, all of the temperature data can be
directly related to the coordinates of the object as seen from all
sides.
[0047] A method for associating the temperatures measured by the
temperature measurement system with the coordinates of the object
as measured by the AACMM 100 will now be described. A sensor that
measures electromagnetic energy as a way of finding the temperature
of an object may include a single sensor element or multiple sensor
elements. A common type of sensor has an array of sensor elements.
At any particular time, each sensor element has a particular
position in the local frame of reference of the AACMM 100. In
addition, each sensor element has a unique line in the local frame
of reference of the AACMM 100. The line extends from the sensor
element through the effective center of a lens system that sits in
front of the sensor element. The point at which the line intersects
the object is the point about which electromagnetic energy
resulting from the local temperature of the object is projected
toward the sensor element. For a plurality of sensor elements, each
line from a particular sensor element intersects the object at a
different position.
[0048] The coordinates of the point in three-dimensional space that
corresponds to a particular temperature on the object can be found
by locating the object in three dimensional space and then finding
the point at which the line extending from a particular sensor
element intersects the object. One way to establish the position of
the object in three-dimensional space is to measure at least three
non-collinear points on the object with one or more of the
measurement devices of the AACMM 100. These points might be
particular features that are clearly identifiable. For example, a
point might be the center of a sphere or a corner at which three
edges intersect.
[0049] In many cases, a CAD model is available for the thing being
measured. In this case, the CAD model may be made to overlay the
three measured features (points) to obtain a match. In other cases,
the object may have a simple shape--for example, a plane or a
sphere. A simple shape of this sort can be fit to the at least
three measured points. In still other cases, the shape of the
object may not be known. In this instance, the measurement devices
of the AACMM may be used to measure enough points on the object to
establish the shape of the object. In all of these cases, the
measurements by the AACMM enable a mapping of the temperature data
onto a dimensional representation of the object.
[0050] Software provided for use with the non-contact temperature
sensor may reside within the articulated arm itself or within
application software residing in an external computer. Besides
displaying measured temperatures on a display, the software may
also provide a way for the user to compensate the non-contact
temperature sensor or to enter information about emissivity of the
materials being measured.
[0051] As explained hereinabove, a contact temperature sensor may
be used in addition to, or instead of, a non-contact sensor. One
type of contact sensor is attached to a workpiece. Contact sensors
can be obtained with relatively high accuracies--in some cases,
+/-0.1.degree. C. or better. Contact sensors may measure the
temperature of a given point on a workpiece surface continuously
regardless of the position of the AACMM 100. Sensing elements
within a contact temperature sensor may include thermistors, RTDs,
thermocouples, or other devices. The complete temperature sensing
device will typically contain electronics and an electrical cable
in addition to the sensing element. If the object being measured
(the workpiece) is made of a ferromagnetic material such as steel,
the temperature sensor may be coupled to the workpiece using a
magnet. The temperature sensor may be attached to a workpiece using
a fluid or adhesive, for example, a thermal grease or a thermal
epoxy. Alternatively, the temperature sensor may be attached to the
material using an adhesive tape.
[0052] An important use for contact temperature sensors is to
correct for thermal expansion of a workpiece in relation to a
reference temperature. To make this correction, it is necessary to
know the CTE of the material as well as the change in temperature
of the workpiece from the reference temperature. In many cases, the
temperature of the object under test is nearly uniform over a
volume of the object. In this instance, it may be enough to attach
a single temperature sensor to the workpiece. In other cases, it
may be desirable to attach a number of temperature sensors to one
or more workpieces.
[0053] A temperature sensor may be plugged into a wire-line port
such as the USB port 312, for example, or it may be attached to a
wireless port by means of Bluetooth module 232, for example.
Alternatively, the electrical signal from the sensing element may
be delivered in analog form to the articulated arm, where
electrical circuitry, for example on base processor board 204,
converts the signal into a digital temperature value. The measured
temperature value may be delivered to user interface board 202, or
it may be delivered to an external computer.
[0054] The user of the AACMM 100 may enter the CTE of the workpiece
being tested into the user interface board 202, or the user may
enter a range of CTE values for different portions of the workpiece
under test. The user may also enter a reference temperature, which
is often 20.degree. C., into the user interface. The user interface
board 202 may process the data for viewing on the display 338
within the AACMM 100. Alternatively, it may export data to an
external computer.
[0055] There are many ways in which the temperature data can be
used by the user interface board 202 or external computer. For
example, an expansion factor=1+(measured temperature-reference
temperature)*CTE may be calculated. The expansion factor is also
equal to (L+delta L)/L, where L is a length and delta L is a
corresponding change in length. The expansion factor, or any other
factor that combines the effects of measured temperature, reference
temperature, and CTE, may be used by the user interface board 202
or an external computer. One simple and important way that an
expansion factor can be used is to calculate the dimensions the
workpiece, normalized to the reference temperature. The calculated
dimensions may be referenced by the user interface board 202 to a
global frame of reference or to datums on the workpiece. In this
way, expansion of the workpiece between any two points is made
available and can be graphically visualized. Corrections to account
for thermal expansion can be made to points obtained from any
measurement device--for example, a contact probe 118 or an LLP
242.
[0056] Suppose that an operator wants to measure points on a
workpiece with an AACMM 100 and then display the results normalized
to a reference temperature in a global coordinate system. If the
global coordinate system has not been established, the operator may
measure three or more non-collinear points as a way of establishing
the x, y, and z axes of the global coordinate system in terms of
the local coordinate system of the AACMM 100. From this same data,
a mathematical transformation can be established to convert any
coordinates measured by the probe 118 or LLP 242 in the local
coordinate system of the AACMM 100 into the global coordinate
system. For example, the transformation may be carried out by a
4.times.4 transformation matrix that performs a rotation and a
translation. Such transformations are well known to those of
ordinary skill in the art and will not be discussed further. To
normalize the coordinate values displayed in the global coordinate
system to a reference temperature, each of the three measured
values x, y, and z of a point is multiplied by an expansion factor
obtained using the method described hereinabove. The normalized
coordinate values can be shown on the display 338 or sent to an
external computer for display or further processing. One advantage
of sending normalized data to an external computer is that the
operator can have confidence that the temperature corrections have
been performed correctly by the user interface board 202. This can
save time by eliminating the need to verify the accuracy of the
normalization calculation for each type of application software
used with AACMM 100.
[0057] If CAD data is available, the dimensions of the workpiece,
as measured by the AACMM 100, may be normalized to the reference
temperature and then compared to the CAD model having dimensions
specified at the same temperature. Deviations in dimensions from
the specified values may be shown on display 338 or on an external
computer using color, gray scale, contour map, or whiskers, for
example.
[0058] In some cases, it may be desirable to attach several contact
temperature sensors to one or more workpieces. One method of doing
this is to multiplex the several temperature sensors into one port
(wire-line or wireless) of the AACMM 100 and then collect the
temperature readings sequentially. An alternative method is to
attach each temperature sensor to a different port on the AACMM
100.
[0059] Technical effects and benefits include the ability to
continuously measure temperature and changes in temperature of an
object being measured by the AACMM 100. As such, the operator may
be alerted to changes and take corrective action. Such action may
include moving the object under test to a more suitable measurement
environment or giving the object time to come to thermal
equilibrium. Alternatively, software may be used to normalize test
results to account for the temperature and the CTE of the object
under test. In addition, the non-contact temperature sensor may be
used to measure as an end in itself by measuring the temperature of
an object as a function of position on the object. The dimensional
information provided by the AACMM 100 can be used to accurately map
the measured temperature onto a CAD model of the object under test.
This is useful to engineers in determining whether designs need to
be changed and in providing accurate information for finite element
models.
[0060] As will be appreciated by one skilled in the art, aspects of
the present invention may be embodied as a system, method, or
computer program product. Accordingly, aspects of the present
invention may take the form of an entirely hardware embodiment, an
entirely software embodiment (including firmware, resident
software, micro-code, etc.) or an embodiment combining software and
hardware aspects that may all generally be referred to herein as a
"circuit," "module" or "system." Furthermore, aspects of the
present invention may take the form of a computer program product
embodied in one or more computer readable medium(s) having computer
readable program code embodied thereon.
[0061] Any combination of one or more computer readable medium(s)
may be utilized. The computer readable medium may be a computer
readable signal medium or a computer readable storage medium. A
computer readable storage medium may be, for example, but not
limited to, an electronic, magnetic, optical, electromagnetic,
infrared, or semiconductor system, apparatus, or device, or any
suitable combination of the foregoing. More specific examples (a
non-exhaustive list) of the computer readable medium would include
the following: an electrical connection having one or more wires, a
portable computer diskette, a hard disk, a random access memory
(RAM), a read-only memory (ROM), an erasable programmable read-only
memory (EPROM or Flash memory), an optical fiber, a portable
compact disc read-only memory (CD-ROM), an optical storage device,
a magnetic storage device, or any suitable combination of the
foregoing. In the context of this document, a computer readable
storage medium may be any tangible medium that may contain, or
store a program for use by or in connection with an instruction
execution system, apparatus, or device.
[0062] A computer readable signal medium may include a propagated
data signal with computer readable program code embodied therein,
for example, in baseband or as part of a carrier wave. Such a
propagated signal may take any of a variety of forms, including,
but not limited to, electro-magnetic, optical, or any suitable
combination thereof. A computer readable signal medium may be any
computer readable medium that is not a computer readable storage
medium and that can communicate, propagate, or transport a program
for use by or in connection with an instruction execution system,
apparatus, or device.
[0063] Program code embodied on a computer readable medium may be
transmitted using any appropriate medium, including but not limited
to wireless, wireline, optical fiber cable, RF, etc., or any
suitable combination of the foregoing.
[0064] Computer program code for carrying out operations for
aspects of the present invention may be written in any combination
of one or more programming languages, including an object oriented
programming language such as Java, Smalltalk, C++, C# or the like
and conventional procedural programming languages, such as the "C"
programming language or similar programming languages. The program
code may execute entirely on the user's computer, partly on the
user's computer, as a stand-alone software package, partly on the
user's computer and partly on a remote computer or entirely on the
remote computer or server. In the latter scenario, the remote
computer may be connected to the user's computer through any type
of network, including a local area network (LAN) or a wide area
network (WAN), or the connection may be made to an external
computer (for example, through the Internet using an Internet
Service Provider).
[0065] Aspects of the present invention are described with
reference to flowchart illustrations and/or block diagrams of
methods, apparatus (systems) and computer program products
according to embodiments of the invention. It will be understood
that each block of the flowchart illustrations and/or block
diagrams, and combinations of blocks in the flowchart illustrations
and/or block diagrams, may be implemented by computer program
instructions.
[0066] These computer program instructions may be provided to a
processor of a general purpose computer, special purpose computer,
or other programmable data processing apparatus to produce a
machine, such that the instructions, which execute via the
processor of the computer or other programmable data processing
apparatus, create means for implementing the functions/acts
specified in the flowchart and/or block diagram block or blocks.
These computer program instructions may also be stored in a
computer readable medium that may direct a computer, other
programmable data processing apparatus, or other devices to
function in a particular manner, such that the instructions stored
in the computer readable medium produce an article of manufacture
including instructions which implement the function/act specified
in the flowchart and/or block diagram block or blocks.
[0067] The computer program instructions may also be loaded onto a
computer, other programmable data processing apparatus, or other
devices to cause a series of operational steps to be performed on
the computer, other programmable apparatus or other devices to
produce a computer implemented process such that the instructions
which execute on the computer or other programmable apparatus
provide processes for implementing the functions/acts specified in
the flowchart and/or block diagram block or blocks.
[0068] The flowchart and block diagrams in the Figures illustrate
the architecture, functionality, and operation of possible
implementations of systems, methods, and computer program products
according to various embodiments of the present invention. In this
regard, each block in the flowchart or block diagrams may represent
a module, segment, or portion of code, which comprises one or more
executable instructions for implementing the specified logical
function(s). It should also be noted that, in some alternative
implementations, the functions noted in the block may occur out of
the order noted in the Figures. For example, two blocks shown in
succession may, in fact, be executed substantially concurrently, or
the blocks may sometimes be executed in the reverse order,
depending upon the functionality involved. It will also be noted
that each block of the block diagrams and/or flowchart
illustration, and combinations of blocks in the block diagrams
and/or flowchart illustration, may be implemented by special
purpose hardware-based systems that perform the specified functions
or acts, or combinations of special purpose hardware and computer
instructions.
[0069] While the invention has been described with reference to
example embodiments, it will be understood by those skilled in the
art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this invention, but that the invention will include
all embodiments falling within the scope of the appended claims.
Moreover, the use of the terms first, second, etc. do not denote
any order or importance, but rather the terms first, second, etc.
are used to distinguish one element from another. Furthermore, the
use of the terms a, an, etc. do not denote a limitation of
quantity, but rather denote the presence of at least one of the
referenced item.
* * * * *