U.S. patent application number 09/730159 was filed with the patent office on 2002-06-06 for air jet board device.
Invention is credited to Berlin, Andrew A., Biegelsen, David K., Cheung, Patrick C.P., Noolandi, Jaan.
Application Number | 20020066997 09/730159 |
Document ID | / |
Family ID | 24934187 |
Filed Date | 2002-06-06 |
United States Patent
Application |
20020066997 |
Kind Code |
A1 |
Noolandi, Jaan ; et
al. |
June 6, 2002 |
AIR JET BOARD DEVICE
Abstract
An air jet game comprising an air jet conduiting member having a
plurality of air jet outlets and a controller adapted to
selectively control at least partially, the flow of air out of the
air jet outlets in order to move an object located in an air flow
path of the outlet in a desired direction.
Inventors: |
Noolandi, Jaan;
(Mississauga, CA) ; Biegelsen, David K.; (Portola
valley, CA) ; Cheung, Patrick C.P.; (Castro Valley,
CA) ; Berlin, Andrew A.; (San Jose, CA) |
Correspondence
Address: |
Geza C. Ziegler, Jr.
Perman & Green, LLP
425 Post Road
Fairfield
CT
06430
US
|
Family ID: |
24934187 |
Appl. No.: |
09/730159 |
Filed: |
December 5, 2000 |
Current U.S.
Class: |
273/126A ;
273/119B |
Current CPC
Class: |
B65H 2406/1132 20130101;
A63F 7/3603 20130101; B65H 29/245 20130101; A63F 7/066 20130101;
A63F 7/06 20130101; B65H 2406/14 20130101 |
Class at
Publication: |
273/126.00A ;
273/119.00B |
International
Class: |
A63F 007/07 |
Claims
What is claimed is:
1. An air jet game comprising: an air jet conduiting member having
a plurality of air jet outlets; and a controller adapted to
selectively control at least partially, flow of air out of the air
jet outlets in order to move at least one object located in an air
flow path of the outlet in a desired direction.
2. The air jet game of claim 1 wherein the air jet conduiting
member comprises: an array of electrostatic flap valves, each flap
valve associated with a corresponding air jet outlet, wherein the
flow of air through each air jet outlet is selectively controlled
at least partially by the associated electrostatic flap valve; and
an array of sensors adapted to detect a position of the object.
3. The air jet game of claim 2 wherein the array of sensors
comprises an optical sensor array.
4. The air jet game of claim 2 wherein the array of sensors
comprises an array of linear CMOS sensor bars.
5. The air jet game of claim 1 wherein each air jet outlet is
adapted to provide an air flow of several tenths of a millinewton
of shear force.
6. The air jet game of claim 1 wherein the object is supported and
accelerated over the member without physical contact with the
member.
7. The air jet game of claim 1 wherein the member comprises a
two-sided air channel.
8. The air jet game of claim 1 wherein the member comprises a
single sided air table.
9. The air jet game of claim 1 wherein the controller further
includes at least one position control device, the position control
device being adapted to provide a control input to the controller,
the control input corresponding at least partially to the desired
direction of movement of the object.
10. The air jet game of claim 9 wherein the position control device
is further adapted to provide three degrees of freedom of the
object parallel to the member.
11. A method of controlling the movement of at least one object in
an air jet board game comprising the steps of: detecting a position
of the object; moving the object in a desired direction by one or
more air jets in the board, the step of moving comprising each air
jet being selectively energized based upon the detected position of
the object and a respective control input corresponding to a
desired direction and a desired velocity for the object; and
scoring points in the game by moving the object past a goal area on
the board.
12. The method of claim 11, wherein the step of moving the object
further comprises the step of using a position control device to
provide the control input in order to selectively energize the air
jets.
13. The method of claim 11, wherein the step of detecting a
position of the object comprises the step of sensing an edge
position of the object in at least two dimensions.
14. An air jet object mover game comprising: an array of air jets;
an array of object sensors; and a first controller and a second
controller coupled to the array of air jets and the array of object
sensors, the first and second controllers being adapted to
selectively control a movement of one or more objects over the
array of air jets by selectively activating one or more of the air
jets based upon a detected position of the object by the object
sensors and a desired direction of movement of the object.
15. The game of claim 14 wherein the first controller and the
second controller are 3-degree of freedom joysticks.
16. The game of claim 14 wherein the array of air jets comprises: a
two-sided printed circuit board, the printed circuit board
including a plurality of vias to allow air to flow from a plenum on
one side of the printed circuit board to an associated
electrostatic flap valve on an other side of the printed circuit
board; and an air jet plate mounted on the other side of the
printed circuit board, the air jet plate including a plurality of
air jets, each air jet associated with one of the electrostatic
flap valves and adapted to allow the air to flow from the flap
valve through the air jet.
17. The game of claim 15 wherein each flap valve is adapted to be
connected to an electric potential in order to manipulate the flap
valve between an open and closed position.
18. The game of claim 14, wherein the array of sensors is adapted
to detect an edge position of the object in at least two
dimensions.
19. The game of claim 14, wherein the first controller and the
second controller are each adapted to compare a sensed position of
the object with a desired position of the object and selectively
energize the air jets in order to generate a force and a torque to
null the differences.
20. The game of claim 19 wherein the first controller and the
second controller uses a force allocation algorithm to determine
the flap valves to be opened and closed to best approximate the
force and the torque to null the differences.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to airjet object movement
systems, and more particularly, to an airjet board game.
[0003] 2. Prior Art
[0004] Systems for supporting objects with a controlled fluid flow
are known. For example, U.S. Pat. No. 6,004,395, which is commonly
owned by Applicants' assignee and the disclosure of which is
incorporated herein by reference, discloses a valve array for
supporting objects, such as paper, with controlled fluid flow.
SUMMARY OF THE INVENTION
[0005] The present invention is directed to, in a first aspect, an
air jet game. In one embodiment, the air jet game comprises an air
jet conduiting member having a plurality of air jet outlets and a
controller adapted to selectively control at least partially, the
flow of air out of the air jet outlets in order to move at least
one object located in an air flow path of the outlet in a desired
direction.
[0006] In another aspect, the present invention is directed to a
method of controlling the movement of an object in an air jet board
game. In one embodiment, the method comprises detecting a position
of the object, and moving the object in a desired direction by one
or more air jets in the board. The step of moving comprises each
air jet being selectively energized based upon the detected
position of the object and a respective control input corresponding
to the desired direction and desired velocity of the object. Points
are scored in the game by moving the object past a goal area on the
board.
[0007] In a further aspect, the present invention is directed to an
air jet object mover game. In one embodiment, the air jet object
mover comprises an array of air jets, an array of object sensors,
and a first controller and a second coupled to the array of air
jets and the array of object sensors. Each controller is adapted to
selectively control the movement of the object over the array of
air jets by selectively activating one or more of the air jets
based upon on a detected position of the object by the object
sensors and a desired direction of movement of the object.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The foregoing aspects and other features of the present
invention are explained in the following description, taken in
connection with the accompanying drawings, wherein:
[0009] FIG. 1 is a block diagram of one embodiment of an airjet
board game incorporating features of the present invention.
[0010] FIG. 2 is a block diagram of one embodiment of an airjet
system incorporating features of the present invention.
[0011] FIG. 3 is a cross-sectional view of a pair of airjets
levitating and accelerating an object in one embodiment of a system
incorporating features of the present invention.
[0012] FIG. 4 is a graphical representation of the measured lateral
force per jet versus pressure drop across a jet and plenum pressure
for one embodiment of a system incorporating features of the
present invention.
[0013] FIG. 5 is a cross-sectional view of one embodiment of an
electrostatic flap valve incorporating features of the present
invention.
[0014] FIG. 6 is a pictorial representation of one embodiment of a
flap valve configuration incorporating features of the present
invention stroboscopically observed from above and from the
side.
[0015] FIG. 7 is a graphical representation of valve conductance
versus valve voltage for one embodiment of a flap valve
configuration incorporating features of the present invention.
[0016] FIG. 8 is a side elevational view of a section of one
embodiment of single side air table incorporating features of the
present invention.
[0017] FIG. 9 is a side elevational view of a section of one
embodiment of a two-side air channel incorporating features of the
present invention.
[0018] FIG. 10 is an elevational view of one embodiment of an
airjet module incorporating features of the present invention.
[0019] FIG. 11 is a flowchart of a control architecture for one
embodiment of a system incorporating features of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0020] Referring to FIG. 1, a block diagram of a game 10
incorporating features of the present invention is shown. Although
the present invention will be described with reference to the
embodiments shown in the drawings, it should be understood that the
present invention can be embodied in many alternate forms of
embodiments. In addition, any suitable size, shape or type of
elements or materials could be used.
[0021] Generally, the system or game 10 comprises an air jet
conduiting member 12, also referred to as an airjet board, and a
movable object 44. The game may also include a controller 14 that
is adapted to allow a user to control the position and movement of
the object 44 on the board. The game 10 may also include one or
more positioning control devices 20. In one embodiment, the
positioning control device 20 can comprise a joystick. A user can
use the joystick 20 to control the position and movement of a
movable object 44 on the board 12. It is a feature of the present
invention to allow one or more users to control the movement of one
or more objects 44 over the board 12 in a game. A game can involve
controlling the flow of air along a surface of the board 12 in
order to move the object over the board 12. In one embodiment, the
object 44 could be levitated over the board 12. For example, a game
may comprise a user playing against another user or a computer as
an opponent, and attempting to control the movement of one or more
objects 44 on the board 12.
[0022] In one embodiment, the airjet board 12 comprises a plurality
of airjets 42 and sensors 38. The member 12 may also include one or
more connectors 82 for coupling the member 12 to the controller 14,
coupling the member 12 to another member 12, or for coupling the
member 12 to other suitable devices. In one embodiment, the game 10
also includes the positioning control device 20 that is adapted to
control the movement of the object 44 along or over the board 12.
The positioning control device 20 may be coupled to the controller
14 and can be adapted to provide positioning commands to the
controller 14. In one embodiment, the positioning device 20 can be
an integral part of the controller 14. In an alternate embodiment,
the game 10 can include such other suitable components for
controlling the position of an object with an airjet.
[0023] As shown in FIG. 2, in one embodiment, the air jet
conduiting member 12 can comprise a valve board 40 and a sensor
board 36. Generally, the valve board 40 comprises an array of
airjets 42 and may include a plurality of openings 37 for sensors
38. The sensor board 36 comprises an array of sensors 38.
Generally, the airjets 42 can be used to move an object on the
board, for example by rolling, and/or levitate the object 44 above
the board 12. The sensors 38 detect the position of the object 44
on or over the board 12. In an alternate embodiment, the game 10
may include such other suitable components for moving an object 44
with an air jet system. It is a feature of the present invention to
provide a system for moving an object 44 in three degrees of
freedom without making physical contact with the object 44.
Generally, the object 44 comprises a lightweight flexible medium,
such as for example, a sheet of paper or a disk like object that
can be levitated over the board 12. The disk can comprise any
suitable material, such as for example, plastic. In an alternate
embodiment, the object 44 can make contact with the board 12 at a
point and be moved along the board 12 by the airjet 42 in a rolling
or sliding fashion. For example, the object can comprise a hollow
or semi-hollow sphere or disk which rolls on the board and can
comprise any suitable material such as for example, plastic.
[0024] FIG. 3 is a cross-section of an object 44 being levitated
and accelerated by a pair of airjets 42 in an air channel 46, in an
exemplary 2-sided embodiment of the present invention. Arrays of
simple cylindrical orifices pass through the plates oriented, in
one embodiment, at approximately 45 degrees with respect to the
plate normal. A small pressure gradient along an orifice passage 42
creates a jet of air as shown in FIG. 3. In an alternate
embodiment, any suitable number of airjets in any suitable
orientation can be used to move the object 44. It is a feature of
the present invention to levitate and move an object 44 at high
accelerations and peak velocities. As shown in FIG. 3, three
dimensionally confined airjets 42 impinge on the sheet 44 and apply
localized shear stress on the sheet 44. Fluid jets directed with a
velocity component normal to the surface of the object 44 must have
their flow redirected. Conservation of total momentum implies some
direct momentum transfer to the object 44 along the channel 46.
Another force acting on the object 44 exerts a shear force on the
surface of the object 44 due to the viscous momentum exchange in a
velocity gradient. The viscous drag slows the fluid, or air, and
accelerates the object 44. The boundary layer is the fluid or air
region adjacent to the surface of the object in which the velocity
transitions from the velocity of the solid bounding surface to
nearly the fluid velocity far from the surface. In one embodiment,
the boundary layer thickness, approximately 1 mm, is considerably
greater than the root mean square height variations characterizing
the texture of most paper stocks. Thus, the shear force exerted is
approximately independent of the surface texture of the object
44.
[0025] The downstream air spreads out laterally and vertically, and
produces far less lateral force on the sheet 44. Forces are
dominated by those created in the jet impingement zones. Generally,
air spreading out in the channel 46 downstream slows and disperses.
At the low Reynolds numbers encountered here (Re<1000), flows
are laminar. The lateral forces on the sheet 44 are given by the
Newtonian law of friction, F=.mu. dv.sub.x/dy, where .mu. is the
dynamic viscosity, v.sub.x is the velocity along the channel 46, y
is the dimension perpendicular to the channel 46. The shear
velocity gradient, dv.sub.x/dy, is far greater in the impingement
zone than downstream.
[0026] The shear force on the sheet 44 depends weakly on the
incident angle and distance of paper from jet plate 48, and is
approximately proportional to the pressure drop across the airjet
42, as is represented in the graph of FIG. 4. Plenum pressure, as
will be described below, is generally higher than the pressure
across the jet 42 for the valve embodiment described. In an
alternate embodiment, the plenum pressure can be of any suitable
magnitude relative to the pressure across the jet 42. In one
embodiment, the magnitude of the lateral force is typically 0.1 mN
per jet.
[0027] The flow of air through an airjet 42 can generally be
modulated by a valve mechanism 70 as shown in FIG. 5. In one
embodiment, the valve mechanism 70 can comprise a plenum 52, an
electrostatic flap valve 50, and an airjet 42. In an alternate
embodiment, the valve mechanism 70 can include any suitable valve
mechanism and structure adapted to control the flow of air to the
jet 42. Although the embodiments of the present invention described
herein are discussed in terms of "air", "airjets" and "air flow",
any suitable fluid can be used other than including "air".
[0028] The electrostatic flap valve 50 is generally capable of
switching on and off jet flows that can provide several tenths of a
milli-newton of shear force. The flap valve generally includes an
upper electrode 64 and a lower electrode 62, across which an
electric potential can be applied. The flap valve 50 can comprise
any suitable material such as for example, polyester. The electrode
material 64 can comprise an electrically conducting material, such
as for example, aluminum or copper. In one embodiment, the lower
electrode 62 and upper electrode 64 are electrically connected to a
common potential, such as for example, a ground potential. As shown
in FIG. 5, in that embodiment, pressurized air in the plenum 52
blows through a valve orifice or via 60 and out of the airjet 42 if
there is no voltage drop across the flap valve 50. When a voltage
is applied between electrodes 62 and 64, the upper electrode 64 is
attracted to the lower electrode 62. The flap valve 50 closes and
seals the valve orifice 60.
[0029] The fabrication of flap valve mechanism 70 can generally
comprise fabricating a 2-sided or multilayer printed circuit board
58 ("PCB") by standard means with an array of 1.5 mm diameter
holes. The holes act as vias both for connecting the lower and
upper copper traces on the PCB 58 as well as for providing air to
the valve 50 from the plenum 52 below the PCB 58. In one
embodiment, a gasket plate 56 can be laminated to both sides of the
PCB 58. The gasket plate 56 can comprise an acrylic plate 2 mm in
thickness, with thin film adhesive layers. In alternate
embodiments, the gasket plate 56 can comprise any suitable
material, such as for example, FR4, ceramic or flex. The gasket
plate 56 can be laser cut to pattern the gasket around the valve
orifice 60. In one embodiment, a supporting layer 54 can be used to
facilitate handling and dimensional stability of the thin film. The
supporting layer 54 can comprise an aluminized, 6-micron thick
polyester sheet laminated onto a 250 microns thick polyester layer,
although other suitable supporting materials may be used. After
laser cutting, the thin film is aligned and bonded to the bottom of
the gasket plate 56. A jet plate 48 including the airjets 42, can
be aligned and laminated to the gasket plate 56. In one embodiment,
the jet plate 48 can be laser cut to form 1 mm diameter holes
tilted at 45.degree. and oriented in the four cardinal directions
to form the airjets 42. In an alternate embodiment, the jet plate
48 can comprise a multiple layer structure with holes spatially
shifted by a fraction of a hole diameter in each layer which are
aligned and stacked to provide the tilted air jets 42. Each layer
in the multilayer structure can be formed by drilling, die cutting
or photolithography, for example. The upper valve assembly 68,
including the gasket plate 56 and the jet plate 48, can be affixed
to the PCB 58. In one embodiment where a polyester sheet is used as
the supporting layer 54, the polyester sheet is removed from the
polyester flap valve array and the upper valve assembly 68 is
laminated to the PCB 58. In one embodiment, a 50 micron thick
adhesive can be used that compresses against the flap valve 50
material and bridges to the PCB 58.
[0030] In order to manipulate a flap valve 50 in an array of valves
on the board 40, a common voltage is applied to the top electrode
64 of all flap valves 50 and the bottom electrodes 62 of each flap
valve 50 are addressed individually. The electrostatic forces must
be satisfactory to overcome the aerodynamic forces associated with
flows necessary to adequately accelerate the object 44.
[0031] FIG. 6 shows a flap valve 50 being optically strobed at
variable delays after the valve voltage is raised or lowered. The
images obtained on video camera through a microscope show the
stages of valve opening and closing seen from above (upper frames)
and from a side (lower frames). The figures in the upper row A show
selected frames for a flap valve 50 opening and lower row B shows a
sequence while the flap valve 50 is closing. The plenum pressure in
the valve mechanism 70 for the embodiment shown was 0.5 kPa
({fraction (1/200)} of an atmosphere) above atmosphere, the closing
voltage was 300 V, and the opening voltage was 0 V. The flow
through the opening valve under these conditions was 0.02 L/s.1. In
the closing sequence the flap valve 50 first zips rapidly up to the
orifice 60 then slows where the curvature increases as the flap
valve 50 starts to close off the flow through the orifice 60. As
the flap valve 50 approaches closure a "tunnel" is formed in the
last one or more milliseconds before complete sealing. The closing
time is taken to be the time when complete sealing occurred. On
opening, the center of the flap valve 50 balloons up and the
effective area of the aperture increases until the declining
electrostatic force of the remaining flap can no longer withstand
the increasing pneumatic force. After release, the flap valve 50
quickly rises to about half height then drifts more slowly to a
larger height. The higher the pressure the faster the flap valve 50
is blown open. Similarly for high pressures and flows, the flap
curvature is increased, the electrostatic forces are decreased, and
the flap valve 50 takes longer to zip shut. Beyond about 1 kPa,
under the conditions used here the flap valve 50 no longer can
close. By changing gasket shape, valve orifice diameter, etc.,
closing pressure drops can be increased to several kpa.
[0032] Generally, the pressure is dropped across the flap valve 50
and airjet 42 in series. The impedance of a 4 mm long, 1 mm
diameter jet 42 is very nearly equal to that of a 1 mm diameter
aperture. The flow through an aperture at these small pressure
drops is proportional to the square root of the pressure drop. The
impedance, .DELTA.P/F, where F is the mass flow under the pressure
gradient .DELTA.P, is thus not a constant. Series impedances add in
quadrature. For an inlet aperture with area A.sub.i and outlet
aperture with area A.sub.o in series, the pressure at the midpoint,
i.e. in the gasket volume, rapidly equilibrates to
P=P.sub.o+.DELTA.P.sub.i/(r.sup.2+1), where r is the ratio
A.sub.o/A.sub.i and .DELTA.P.sub.i-P.sub.o is the pressure drop
from plenum 52 to jet exhaust. This is useful in determining the
behavior of a flap valve 50 in conjunction with a particular
diameter jet 42.
[0033] FIG. 7 is a schematic drawing of the hysteretic behavior of
one embodiment of the present invention showing the steady state
valve conductance as a function of valve voltage for a plenum
pressure of 0.5 kPa. At zero volts the compliant flap valve 50 is
blown open into a stable, inflected curve. For applied voltages
less than 220 V the flap valve 50 zips up to the orifice 60 and
stops. For voltages higher than 220 V the flap valve 50 zips to
closure with the total elapsed time to completion decreasing with
increasing voltage. Similarly, dropping the voltage to greater than
120 V does not allow the flap valve 50 to open because the
electrostatic force is much greater when the flap valve 50 is shut
than when it is open because of the finite curvature in the latter
case. Thus, the voltage must be increased for an open flap valve 50
to overcome this barrier resulting in a hysteretic behavior.
[0034] Below 120 V the flap valve 50 is opened by the held-off
pressure with times as shown in FIG. 7. Thus, the flexible
electrostatic valves described here can be seen to have large
stroke but have a region of sufficiently low curvature so that the
gap between electrodes is small enough to provide electric fields
strong enough to zip the membrane along. FIG. 7 also plots the
opening times at low voltages and the closing times at high
voltages. As shown, the higher the voltage the faster the flap
valve 50 snaps shut, and the lower the voltage the faster the flap
valve 50 pops open.
[0035] Another method used to characterize valve response, a method
that is more functionally relevant, utilizes a silicon membrane
pressure sensor, stripped of its packaging. The sensor is
positioned at the impingement zone of a jet 42. The time dependence
of the stagnation pressure of the jet, and therefore the time
dependence of the flow in the channel, is determined from the
response of the sensor. The measured flow generally follows the
driving pulse except that both turn-on and turn-off have
approximately a 1 ms delay and have<1 ms rise and fall time.
There is a seeming discrepancy between the flow response times and
the stroboscopic measurements of flap transition times, for both
closing and opening the flow transitions occur more quickly. The
difference arises predominantly from the variation in flow
impedance of the valve when the flap valve 50 is near closure. The
impedance of the flap valve 50 when the flap is near the lower
electrode 62 increases strongly as the gap decreases. The impedance
of the "tunnel" feature is much higher than that of the open valve.
Therefore, the time to full visual closure overestimates the time
of significant flow. Similarly, the impedance of the valve is
limited by the impedance of the jet 42 when the flap valve 50 is
well above the electrode 62. Therefore, when the flap valve 50
rises beyond a height of about d/4, where d is the diameter of the
valve orifice 60, the flow is saturated. So again the stroboscopic
estimate exceeds the flow response time. Another characteristic
feature of the flow response is the approximately 1 millisecond
delay between voltage drive and flow response. This is a
convolution of the flap response time and the time constant for
pressurizing and de-pressurizing the gasket volume, estimated to be
1-2 millisecond.
[0036] Lifetime tests were run on an array of 120 valves by driving
the valves in parallel with a 10 millisecond repetition time.
Driving was terminated after 400 million repetitions with no valve
failures and negligible charge injection-induced voltage shifts.
The flap valves 50 are thus shown to be very reliable, most likely
because the small curvatures of the flaps lead to negligible
plastic deformation of the polyester or aluminum. Furthermore,
having the aluminum above the plastic minimizes abrasion of both
the aluminum and copper.
[0037] To enable controlled manipulation of the object 44, the
position of the object 44 must be sensed. As shown in FIG. 2, the
air jet member assembly 12 may also include a sensor board 36.
Generally, the sensor board 36 comprises an array of sensors 38
that are adapted to detect the position of the object 44 in two or
more dimensions. In one embodiment, the sensor board 36 can
comprise an array of linear CMOS sensor bars 38, having for
example, an internal pixel pitch of 64 microns, to detect edge
positions of the object 44 in two dimensions. In an alternate
embodiment, any suitable means to detect a position of the object
may be used, such as for example, a distributed optical sensor on
the same PCB containing the actuators and computational electronics
or an amorphous silicon or organic sensor array. In one embodiment,
the levitated object is illuminated, either in transmission or
reflection, and the contrast between the light levels with the
object 44 absent and present are detected optically as edge
transitions. For example, as shown in FIG. 9, Lambertian
illumination from above casts a shadow of the object 44 which is
imaged by a SelFoc.TM. array 76 onto the CMOS sensor 38. In one
embodiment, a collimator 74 may overlay the sensor array 36 as
shown in FIG. 8. All 1280 gray level pixels of all sensors are
latched simultaneously and then clocked out every millisecond and
binarized using a processor-set threshold. As shown in FIG. 2, a
field programmable gate array (FPGA) 26 can be used to filter the
outputs into acceptable edge transitions. The transitions can be
passed to a digital signal processor (DSP) 18 to infer the position
and rotation state of the object 44. In one embodiment, the desired
position and orientation for the object 44 can be entered into the
DSP 18 from a canned trajectory or from a three degree of freedom
joystick 20 as shown in FIG. 2. Alternately, any suitable
positioning device can be used to enter a desired position and
trajectory of the object 42. The DSP 18 compares the sensed state
of the object as determined by the sensor array 36 with the desired
state as determined by the joystick 20, and generates the forces
and torques required to null the differences. The DSP 18 is
generally adapted to convert the transitions into a spatial map of
edge crossings, and can generate a rectangle, a shape or multiple
shapes which best fit through those transitions. A force allocation
algorithm can then be used to determine which valves 50 should be
opened and closed to best approximate the desired forces and
torques. The commands can then be sent to another FPGA 26 which is
adapted to drive the high voltage arrays 30 to enable the valve 50
transitions. In one embodiment, the control loop is pipelined with
the sensing so that the entire feedback looping occurs within
approximately one millisecond.
[0038] In the embodiment shown, control in the system 10 is
centralized. Alternate embodiments may utilize distributed
computation and control. The algorithm, operating with an
approximately 25 Hz closed loop bandwidth, is a simple first order
lead controller which can use history to disambiguate nearly
equivalent fits of rectangles to the set of edge locations.
Position is generally held to approximately 25 microns for
statically positioned levitated objects, and tracking accuracy is
approximately 75 microns for rapidly moving trajectories (such as
circles and steps). Although the present invention is described in
terms of moving an object, it should be understood that the
controller can also be used to hold a relatively stationary
position of the object 44. Generally, the joystick 20 is used to
input a command signal to the controller corresponding to a desired
direction of movement of the object 44. The joystick 20 may also be
adapted to input a desired velocity for the object 44. In alternate
embodiments, the joystick 20 can provide any suitable commands to
the system 10. In one embodiment, the command signal may include a
command to hold a position of the object 44, in which case the
object 44 can be levitated in a relatively stationary position.
[0039] A control architecture flowchart for one embodiment of the
present invention is shown in FIG. 10. Force and torque commands
(Fx, Fy, and Tz are fed through the controller 14 in order to
allocate the valve 50 actuators as indicated in blocks 102 and 104.
The actuator allocation generally includes control commands for
each of the 576 valves in a single sided embodiment of the air
table described above. In an alternate embodiment, an air table
could include any suitable number of valves. Generally, the force
and torque commands depend from a position command(s) (x,y,.theta.)
from the position control device 20 or devices, and the detected
position(s) (x,y,q) of the object or objects. The actuator commands
are processed through the paper and actuator dynamics as indicated
in block 106. The detection of the object 44 can be processed
through sensor-edge processing as indicated in block 108, which can
then be used to determine the position in terms of coordinates
(x,y,q) of the object as indicated in block 110. The control loop
depicted in FIG. 11 allows for accurate control and movement of an
object 44 over a board 12. The system 10 can generally be operated
either as a single sided air table 80 as shown in FIG. 8 or as a
2-sided air channel 90 as shown in FIG. 9. In an alternate
embodiment, the system 10 may be operated with any suitable number
of sides, such as for example, a tunnel. As shown in FIGS. 8 &
9, the system 10 can include a blower 72 to supply air to the
plenum 52. The system 10 can include any suitable number of plenums
52 and blowers 72. The system 10 can also include high voltage
drivers 74. Generally, the 2-sided system 90 has better performance
characteristics due to the increased actuation authority and the
stablilization from a double sided air bearing created by the air
flow from two jets 42 impinging on the object 44. The 2-sided air
bearing effectively stiffens the object and maintains the sheet at
a fixed height (approximately 2 mm above the jet plate 48)
independent of plenum pressure as long as both top and bottom plena
52 are at the same pressures.
[0040] FIG. 10 shows one embodiment of a 12 inch.times.12 inch
30.48 cm.times.30.48 cm airjet object mover module 12 or board
game. Although this embodiment comprises arrays of square modules,
and suitable size or shape of array can be used, such as for
example circular arrays as shown in FIG. 12. In the example shown
in FIG. 10, each actuation PCB 58 consists of 576 valves 50 and
jets 42; 144 (or one per square inch) point in each of the four
cardinal directions. The jets 42 are interleaved with the sensor
bars 38. Sixteen element arrays 78 comprise flap valves 50 and
associated jets 42. The black bars are SelFoc.TM. arrays 76. By
invoking an image of valve openings arbitrary force fields can be
applied to the levitated objects 44. Object motions with three
degrees of freedom (x, y, .theta.) can be controlled, and gray
levels of force can be asserted by changing the number of jets 42
or the time of actuation of jets 42.
[0041] Connectors 82 are provided for coupling to the controller 12
and other related components or devices. In one embodiment, an
airjet module 12 is adapted to be connected to one or more other
airjet modules 12. In this manner, a series of airjet modules 12
can be connected in order to provide a larger platform or a pathway
along which an object 44 can be moved.
[0042] One feature of the system 10 is that due to the individual
airjet 42 control, pieces of paper or other objects 44 can be moved
arbitrarily in a two-dimensional plane. Although the object 44 is
described herein as being flat, any object 44 that can be moved,
roller or levitated by an airjet 42 or series of airjets, can be
used. In one embodiment, a board game application of the system 10
can have one or more players competing to move/block playing pieces
44 using one or more position control devices 20, such as one or
more joysticks. For example, an airjet board game incorporating
features of the present invention could include two 3-degree of
freedom joysticks 20 to allow two or more users to move one or more
objects 44 past each other toward some goals. In another
embodiment, the airjet board game could include an individual user
playing against a computer.
[0043] The system 10 allows for maneuverability of the playing
pieces as well as progammability of the field of play. Games may
include for example, soccer, hockey, and obstacle races.
Programmable fields of play could include for example, hills and
tunnels, where the physical "terrain" of the playing field or board
12 could be modified by the computer.
[0044] In another embodiment, the system 10 could be adapted to
move sheets of paper along a path or sort tiles into desired
patterns.
[0045] The architecture described above provides for the control of
thousands of actuators and sensors. The system described above has
a largely centralized control architecture. The scalability of
control electronics and algorithms for assemblies of numerous
independent agents, particularly for human-scaled systems demands
distributed computation and control. Systems tightly integrating
many actuators, sensors, computational nodes and communication, can
be called "smart matter".
[0046] In designing smart matter systems the boundaries between the
digital and analog worlds are blurred. An example of a smart matter
approach to achieve a scalable control design is an analog "market
wire" developed to perform the force allocation tasks. In one
embodiment of the airjet module 12, each set of four actuators,
pointing in four different directions, is a force agent. One or
more sensors 38 can be associated with each force agent. An analog
circuit and/or micro-controller can be associated with each agent.
Agents can thus sense and act locally, but coherent, larger scale
actions are required. PCBs can have many layers of metal for little
extra expense. An agent, such as a controller 14, can request more
of a commodity, say force in the x direction, by sourcing current
onto such a plane, a market wire, basically a capacitor. The
voltage (the "price" of the x-force) rises. Each agent has vias
connecting to the market wire(s). Producer agents, the airjet
foursomes, consider supplying the x-force. First the local sensor
38 looks up at the object 44. If it is there it makes sense to
participate. Should it turn on? Locally it has a "marginal utility
function" which says, in effect, if the voltage is above a certain
threshold, turn the x-valve on. Then sink current from the x-force
market wire, dropping the "price". Another agent, perhaps far away,
but also under the sheet, asynchronously decides that the price has
now dropped below its threshold and decides not to turn on. The
desired force is thus provided almost instantaneously. The
mechanism is easily scalable. It is essentially independent of the
number of agents on a board. If another board is added to the
system, the market wires are joined and no change in programming is
needed.
[0047] The airjet mover is an exemplar of a smart matter system.
The airjets provide a low-mass system for moving objects in three
degrees of freedom without making physical contact with the
objects.
[0048] It should be understood that the foregoing description is
only illustrative of the invention. Various alternatives and
modifications can be devised by those skilled in the art without
departing from the invention. Accordingly, the present invention is
intended to embrace all such alternatives, modifications and
variances which fall within the scope of the appended claims.
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