Accelerated startup for a balancing personal vehicle Number:6,815,919 from the United States Patent and Trademark Office (PTO) owispatent A method and apparatus that afford a user accelerated access to operation of a balancing personal transporter. The method includes first initializing a single-axis stabilizer, and, while initializing a 3-axis stabilizer, alerting the rider that the transporter is ready for use, allowing operation of the transporter, and then completing initialization of the 3-axis stabilizer, and employing the 3-axis stabilizer for control of the balancing personal transporter. Apparatus includes single axis and 3-axis stabilizer and means to alert the user of the personal transporter.<H Accelerated, balancing, Accelerated, sta, 6815919.html, Patent, pto, 6815919

Title: Accelerated startup for a balancing personal vehicle

Abstract: A method and apparatus that afford a user accelerated access to operation of a balancing personal transporter. The method includes first initializing a single-axis stabilizer, and, while initializing a 3-axis stabilizer, alerting the rider that the transporter is ready for use, allowing operation of the transporter, and then completing initialization of the 3-axis stabilizer, and employing the 3-axis stabilizer for control of the balancing personal transporter. Apparatus includes single axis and 3-axis stabilizer and means to alert the user of the personal transporter.

Patent Number: 6,815,919 Issued on 11/09/2004 to Field, et al.

Inventors: Field; J. Douglas (Bedford, NH); Morrell; John B. (Bedford, NH)
Assignee: DEKA Products Limited Partnership (Manchester, NH)

Appl. No.: 394860

Filed: March 21, 2003

Related U.S. Patent Documents


Application Number	Filing Date	Patent Number	Issue Date
687757	Oct., 2000	6538411

Current U.S. Class: 318/587 ; 180/218; 318/561; 318/575; 318/585; 318/586

Field of Search: 318/560,561,563,566,568.24,575,585-587,597,611,623 180/218

References Cited [Referenced By]

U.S. Patent Documents


584127	June 1897	Draullette et al.
584127	April 1907	Schafer et al.
2742973	April 1956	Johannesen
3145797	August 1964	Taylor
3260324	July 1966	Suarez
3283398	November 1966	Andren
3288234	November 1966	Feliz
3348518	October 1967	Forsyth et al.
3374845	March 1968	Selwyn
3399742	September 1968	Malick
3446304	May 1969	Alimanestiano
3450219	June 1969	Fleming
3515401	June 1970	Gross
3580344	May 1971	Floyd
3596298	August 1971	Durst, Jr.
3610646	October 1971	Bobard et al.
3860264	January 1975	Douglas et al.
3872945	March 1975	Hickman et al.
3920281	November 1975	Brun
3952822	April 1976	Udden et al.
4018440	April 1977	Deutsch
4062558	December 1977	Wasserman
4076270	February 1978	Winchell
4088199	May 1978	Trautwein
4094372	June 1978	Notter
4109741	August 1978	Gabriel
4111445	September 1978	Haibeck
4151892	May 1979	Francken
4222449	September 1980	Feliz
4264082	April 1981	Fouchey, Jr.
4266627	May 1981	Lauber
4293052	October 1981	Daswick et al.
4294420	October 1981	Broquet
4325565	April 1982	Winchell
4354569	October 1982	Eichholz
4363493	December 1982	Veneklasen
4373600	February 1983	Buschbom et al.
4375840	March 1983	Campbell
4510956	April 1985	King
4560022	December 1985	Kassai
4566707	January 1986	Nitzberg
4570078	February 1986	Yashima et al.
4571844	February 1986	Komasaku et al.
4624469	November 1986	Bourne, Jr.
4657272	April 1987	Davenport
4685693	August 1987	Vadjunec
4709772	December 1987	Brunet
4716980	January 1988	Butler
4740001	April 1988	Torleumke
4746132	May 1988	Eagan
4770410	September 1988	Brown
4786069	November 1988	Tang
4790400	December 1988	Sheeter
4790548	December 1988	Decelles et al.
4794999	January 1989	Hester
4798255	January 1989	Wu
4802542	February 1989	Houston et al.
4809804	March 1989	Houston et al.
4834200	May 1989	Kajita
4863182	September 1989	Chern
4867188	September 1989	Reid
4869279	September 1989	Hedges
4874055	October 1989	Beer
4890853	January 1990	Olson
4919225	April 1990	Sturges
4953851	September 1990	Sherlock et al.
4984754	January 1991	Yarrington
4985947	January 1991	Ethridge
4998596	March 1991	Miksitz
5002295	March 1991	Lin
5011171	April 1991	Cook
5052237	October 1991	Reimann
5111899	May 1992	Reimann
5158493	October 1992	Morgrey
5161820	November 1992	Vollmer
5168947	December 1992	Rodenborn
5171173	December 1992	Henderson et al.
5186270	February 1993	West
5221883	June 1993	Takenaka et al.
5241875	September 1993	Kochanneck
5248007	September 1993	Watkins et al.
5314034	May 1994	Chittal
5350033	September 1994	Kraft
5366036	November 1994	Perry
5376868	December 1994	Toyoda et al.
5419624	May 1995	Adler et al.
5701965	December 1997	Kamen et al.
5701968	December 1997	Wright-Ott et al.
5735361	April 1998	Forrest
5775452	July 1998	Patmont
5791425	August 1998	Kamen et al.
5794730	August 1998	Kamen
5971091	October 1999	Kamen et al.
5973463	October 1999	Okuda et al.
5975225	November 1999	Kamen et al.
5986221	November 1999	Stanley
6003624	December 1999	Jorgensen et al.
6039142	March 2000	Eckstein et al.
6039326	March 2000	Agner
6050357	April 2000	Staelin et al.
6059062	May 2000	Staelin et al.
6125957	October 2000	Kauffmann
6131057	October 2000	Tamaki et al.
6223104	April 2001	Kamen et al.
6225977	May 2001	Li
6288505	September 2001	Heinzmann et al.
6302230	October 2001	Kamen et al.
6612389	September 2003	Bell
2002/0063006	May 2002	Burl et al.

Foreign Patent Documents


2 048 593	May., 1971	DE
31 28 112	Feb., 1983	DE
32 42 880	Jun., 1983	DE
3411489	Oct., 1984	DE
44 04 594 A 1	Aug., 1995	DE
196 25 498 C 1	Nov., 1997	DE
298 08 091	Oct., 1998	DE
298 08 096	Oct., 1998	DE
0 109 927	Jul., 1984	EP
0 193 473	Sep., 1986	EP
0 537 698	Apr., 1993	EP
0 958 978	Nov., 1999	EP
980 237	May., 1951	FR
82 04314	Sep., 1982	FR
152664	Feb., 1922	GB
1213930	Nov., 1970	GB
2 139 576	Nov., 1984	GB
52-44933	Oct., 1975	JP
57-87766	Jun., 1982	JP
57-110569	Jul., 1982	JP
59-73372	Apr., 1984	JP
62-12810	Jul., 1985	JP
0255580	Dec., 1985	JP
61-31685	Feb., 1986	JP
63-305082	Dec., 1988	JP
2-190277	Jul., 1990	JP
4-201793	Jul., 1992	JP
6-171562	Dec., 1992	JP
5-213240	Aug., 1993	JP
6-105415	Dec., 1994	JP
7255780	Mar., 1995	JP
WO 86/05752	Oct., 1986	WO
WO 89/06117	Jul., 1989	WO
WO 96/23478	Aug., 1996	WO
WO 98/46474	Oct., 1998	WO
WO 00 75001	Dec., 2000	WO

Other References

Kawaji, S., Stabilization of Unicycle Using Spinning Motion, Denki Gakkai Ronbushi, D, vol. 107, Issue 1, Japan (1987), pp. 21-28. .
Schoonwinkel, A., Design and Test of a Computer-Stabilized Unicycle, Stanford University (1988), UMI Dissertation Services. .
Vos, D., Dynamics and Nonlinear Adaptive Control of an Autonomous Unicycle, Massachusetts Institute of Technology, 1989. .
Vos, D., Nonlinear Control of an Autonomous Unicycle Robot: Practical Isues, Massachusetts Institute of Technology, 1992. .
Koyanagi et al., A Wheeled Inverse Pendulum Type Self-Contained Mobile Robot and its Posture Control and Vehicle Control, The Society of Instrument and Control Engineers, Special issue of the 31.sup.st SICE Annual Conference, Japan 1992, pp. 13-16. .
Koyanagi et al., A Wheeled Inverse Pendulum Type Self-Contained Mobile Robot, The Society of Instrument and Control Engineers, Special issue of the 31.sup.st SICE Annual Conference, Japan 1992, pp. 51-56. .
Koyanagi et al., A Wheeled Inverse Pendulum Type Self-Contained Mobile Robot and its Two Dimensional Trajectory Control, Proceeding of the Second International Symposium on Measurement and Control in Robotics, Japan 1992, pp. 891-898. .
Watson Industries, Inc., Vertical Reference Manual ADS-C132-1A, 1992, pp. 3-4. .
News article Amazing Wheelchair Goes Up and Down Stairs. .
Osaka et al., Stabilization of unicycle, Systems and Control, vol. 25, No. 3, Japan 1981, pp. 159-166 (Abstract Only). .
Roy et al., Five-Wheel Unicycle System, Medical & Biological Engineering & Computing, vol. 23, No. 6, United Kingdom 1985, pp. 593-596. .
Kawaji, S., Stabilization of Unicycle Using Spinning Motion, Denki Gakkai Ronbushi, D, vol. 107, Issue 1, Japan 1987, pp. 21-28 (Abstract Only). .
Schoonwinkel, A., Design and Test of a Computer-Stabilized Unicycle, Dissertation Abstracts International, vol. 49/03-B, Stanford University 1988, pp. 890-1294 (Abstract only). .
Vos et al., Dynamics and Nonlinear Adaptive Control of an Autonomous Unicycle--Theory and Experiment, American Institute of Aeronautics and Astronautics, A90-26772 10-39, Washington, D.C. 1990, pp. 487-494 (Abstract only). .
TECKNICO's Home Page, Those Amazing Flying Machines, http://www.swiftsite.com/technico. .
Stew's Hovercraft Page, http://www.stewcam.com/hovercraft.html. .
Kanoh, Adaptive Control of Inverted Pendulum, Computrol, vol. 2, (1983), pp. 69-75. .
Yamafuji, A Proposal for Modular-Structured Mobile Robots for Work that Principally Involve a Vehicle with Two Parallel Wheels, Automation Technology, vol. 20, pp. 113-118 (1988). .
Yamafuji & Kawamura, Study of Postural and Driving Control of Coaxial Bicycle, Paper Read at Meeting of Japan Society of Mechanical Engineering (Series C), vol. 54, No. 501, (May, 1988), pp. 1114-1121. .
Yamafuji et al., Synchronous Steering Control of a Parallel Bicycle, Paper Read at Meeting of Japan Society of Mechanical Engineering (Series C), vol. 55, No. 513, (May, 1989), pp. 1229-1234. .
Momoi & Yamafuji, Motion Control of the Parallel Bicycle-Type Mobile Robot Composed of a Triple Inverted Pendulum, Paper Read at Meeting of Japan Society of Mechanical Engineering (Series C), vol. 57, No. 541, (Sep., 1991), pp. 154-159..

Primary Examiner: Ro; Bentsu
Attorney, Agent or Firm: Bromberg & Sunstein LLP

Parent Case Text

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application from copending U.S. application Ser. No. 09/687,757, filed Oct. 13, 2000 now U.S. Pat. No. 6,538,411 B1, and incorporated herein by reference.

Claims

What is claimed is:

1. A method for providing a user with accelerated access to operation of a balancing personal transporter, the method comprising: (a) beginning initialization of a single-axis stabilizer and of a 3-axis stabilizer; (b) completing initialization of the single-axis stabilizer, thereby making possible user operation of the transporter using the single-axis stabilizer for control; (c) alerting the user that the transporter is ready for use; (d) allowing the user to operate the transporter under the control of the single-axis stabilizer while initialization of the 3-axis stabilizer is being completed; (e) completing initialization of the 3-axis stabilizer; and (f) employing the 3-axis stabilizer for control of the balancing personal transporter.

2. Apparatus for providing a user with accelerated access to operation of a balancing personal transporter comprising: (a) a single axis stabilizer for limited operation of the personal transporter; (b) a 3-axis stabilizer for full operation of the personal transporter; and (c) means for alerting the user that the single axis stabilizer is operational, thereby permitting limited operation of the personal transporter until the 3-axis stabilizer is operational.

3. The apparatus of claim 2, wherein the single axis stabilizer comprises a solid-state gyroscope.

4. The apparatus of claim 2, wherein the single axis stabilizer comprises a tilt sensor.

5. The apparatus of claim 2, wherein the single axis stabilizer is a stabilizer for the pitch orientation of the transporter.

6. The apparatus of claim 2, wherein the 3-axis stabilizer comprises at least three solid-state gyroscopes.

7. The apparatus of claim 2, wherein the 3-axis stabilizer comprises at least a tilt sensor.

8. The apparatus of claim 2, wherein the 3-axis stabilizer is a stabilizer for pitch, yaw, and roll of the personal transporter.

Description

FIELD OF THE INVENTION

The present application is directed to modes of control for a personal transporter utilizing an electrical power source.

BACKGROUND OF THE INVENTION

Dynamically stabilized transporters refer to personal vehicles having a control system that actively maintains the stability of the transporter while the transporter is operating. The control system maintains the stability of the transporter by continuously sensing the orientation of the transporter, determining the corrective action to maintain stability, and commanding the wheel motors to make the corrective action. If the transporter loses the ability to maintain stability, such as through the failure of a component, the rider may experience discomfort at the sudden loss of balance. For some dynamically stabilized transporters, such as those described in U.S. Pat. No. 5,701,965, which may include a wheelchair for transporting a disabled individual down a flight of stairs, it is essential, for the safety of the operator, that the vehicle continue to operate indefinitely after detection of a failed component. For other dynamically stabilized transporters, however, the operator may readily be capable of safely dismounting from the transporter in case of component failure. It is desirable that control modes be provided for such vehicles from which the operator is capable of safely dismounting in case of mishap.

SUMMARY OF THE INVENTION

In accordance with preferred embodiments of the present invention, a system and method are provided for automatically decelerating a personal transporter of the kind that has a controller for controlling the motion of the transporter. The method has steps of detecting a fault condition, setting a goal value of the control variable, adjusting the control variable at a specified increment in the direction of the goal value, and repeating the prior steps until the control variable equals the goal value. In accordance with alternate embodiments of the invention, the goal value may be zero, the control variable may be transporter speed, and the fault condition may be an open motor winding or a closed brake switch.

In accordance with another aspect of the present invention, a method is provided that affords a user accelerated access to operation of a balancing personal transporter. The method has the steps of initializing a single-axis stabilizer, beginning initialization of a 3-axis stabilizer, alerting the rider that the transporter is ready for use, allowing operation of the transporter, completing initialization of the 3-axis stabilizer, and, finally, employing the 3-axis stabilizer for control of the balancing personal transporter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a personal vehicle lacking a stable static position, for supporting or conveying a subject who remains in a standing position thereon;

FIG. 2 shows a block diagram of the system architecture of an embodiment of the present invention;

FIG. 3 shows a top view of the power source with the top cover removed;

FIG. 4 is a block diagram of the power drive module of an embodiment of the present invention;

FIG. 5 is an electrical model of a motor;

FIG. 6a shows a top view of a rider detector in accordance with an embodiment of the present invention;

FIG. 6b shows a cut side view of the embodiment of FIG. 6a;

FIG. 7 shows an exploded view of a yaw input device in accordance with an embodiment of the present invention;

FIG. 8a is a cross-sectional top view of an elastomer-damped yaw input device, shown in its relaxed position, in accordance with an embodiment of the present invention;

FIG. 8b is a cross-sectional top view of the yaw input device of FIG. 8a shown in a deflected position;

FIGS. 8c and 8d are back and top views, respectively, of the yaw input device of FIG. 8a coupled to a handlebar of a personal transporter in accordance with an embodiment of the present invention;

FIGS. 9a and 9b depict a palm steering device, in a rest state and activated state, respectively, as implemented in a handlebar of a personal transporter in accordance with an embodiment of the present invention;

FIG. 10 is a logical flow diagram of the control program in accordance with embodiments of the present invention;

FIG. 11 is a flow diagram for traction control in accordance with an embodiment of the present invention; and

FIG. 12 is a flow diagram for deceleration-to-zero in accordance for an embodiment of the present invention.

DETAILED OF PREFERRED EMBODIMENTS

A personal transporter may be said to act as `balancing` if it is capable of operation on one or more wheels but would be unable to stand on the wheels but for operation of a control loop governing operation of the wheels. A balancing personal transporter lacks static stability but is dynamically balanced. The wheels, or other ground-contacting elements, that provide contact between such a personal transporter and the ground or other underlying surface, and minimally support the transporter with respect to tipping during routine operation, are referred to herein as `primary ground-contacting elements.`

An embodiment of a balancing personal transporter in accordance with the present invention is depicted in FIG. 1 and designated generally by numeral 10. In certain applications, operation of personal transporter 10 may not require operation for an extended period of time in case of failure. Fail-operative operation may be desirable, however, for a definite period of time in order to allow the transporter to maintain stability while stopping and permitting a user to alight from the vehicle. While certain balancing personal transporters may not be required to operate indefinitely if a component fails, it may, however, advantageously provide fail-detect redundant architecture wherein the critical components such as gyros, batteries, motor windings, and processors are replicated and run in parallel during operation of the transporter. If a failure occurs in one line of components, the parallel line will still maintain the stability of the transporter for at least a short period of time. In accordance with the present invention and as discussed below, the short period of continued operation is advantageously used to bring the transporter to a stop while maintaining balance and then turn off the wheel motors. The transporter is brought to a stop by commanding the transporter to pitch backward as is done in speed limiting.

User 8 is shown in FIG. 1, standing on platform (or `base`) 12 of ground-contacting module 26. Wheels 21 and 22 are shown as coaxial about the Y axis. Steering or other control may be provided by thumbwheels 32 and 34, or by other user input mechanisms described in detail below. A handlebar 14 may be provided on stalk 16 for gripping by the user.

Referring now to FIG. 2, a block diagram is shown of the system architecture of an embodiment of the present invention. A left motor 110 drives a left wheel 20 (shown in FIG. 1) and a right motor 120 drives a right wheel 21. Motors 110 and 120 are preferably DC brushless but may be either AC or DC motors and either brushed or brushless. Each motor is energized by a redundant set of windings 111, 112, 121, 122. Each winding is capable of energizing the motor in the event the complimentary winding is unable to energize the motor. In the discussion below, each redundant component is distinguished by a two letter group identifying either the left (L) or right (R) side of the transporter and either the A group or B group of redundant components. For example, the left motor winding energized by the A group of components is designated as the LA winding.

Each of motor windings 111, 112, 121, 122 is driven by a motor amplifier 132, 133, 142, 143. The A-group amplifiers 132, 133 are supplied by the A-group power supply 131 and the B-group amplifiers 142, 143 are supplied by the B-group power supply 141. The electrical connections between the power supplies and amplifiers and between the amplifiers and motor windings are expected to carry large currents up to 20 to 40 Amperes and are identified by thick lines 105 in FIG. 2.

Each motor 110120 has a shaft feedback device (SFD) 113123 that measures the position or angular velocity of the motor shaft. The SFD is in signal communication with the motor amplifiers driving the motor associated with the SFD. For example, the right SFD 123 associated with the right motor 120 is in signal communication with the RA amplifier 133 and the RB amplifier 143. The SFD is preferably a Hall sensor that determines the position of the shaft, however the SFD may be selected from a variety of sensors such as encoders, resolvers, and tachometers, all listed without limitation for purposes of example. Certain sensors, such as tachometers, may also be used to measure the shaft velocity. Conversion of a signal representing instantaneous shaft velocity to or from a signal representing position is accomplished by integrating or differentiating the signal, respectively.

The A-group amplifiers 132, 133 are commanded by the A processor 135 while the B-group amplifiers 142, 143 are commanded by the B processor 145. Power is supplied to the A processor from the A power source 131 through the A-group DC-DC converter 136. Similarly, the B power source 141 supplies power to the B processor 146 through the B-group DC-DC converter 145. The A-group amplifiers 132, 133, A-group converter 136, and A processor 135 are preferably grouped together into a compartment or tray 130 that is at least partially isolated by a barrier 150 from the B-tray 140 containing the B-group amplifiers, B-group converter, and B processor. Physically separating the A tray 130 and B tray 140 reduces the probability of a common point failure. The barrier 150 acts to delay the propagation of a failure in one tray to the other tray such that the transporter has sufficient time to put the rider in a safe condition to exit the transporter. Similarly, the A power supply 131 is physically separated from the B power supply 141. The A power supply 131 and the components in the A tray 130 are capable of driving both motors 110, 120 for a short period of time, on the order of a few seconds, in the event of a failure in any one of the B-group components. Conversely, the B power supply 141 and the components in the B tray 140 are capable of driving both motors 110, 120 for a short period of time if an A-group component fails.

Although the processors 135, 145 are physically isolated from each other, signal communication is maintained between the processors via communication channels 137, 147. Communication channels 137, 147 are preferably electrical conductors but may also be electromagnetic such as optical, infrared, microwave, or radio. The A channel 137 transmits signals from the A processor 135 to the B processor 145 and the B channel 147 transmits signals from the B processor 145 to the A processor 135. Optical isolators 139, 149 are incorporated into channels 137, 147 to prevent over-voltages from propagating from a shorted processor to the other processor.

Each processor receives signals from a plurality of sensors that monitor the state of the transporter and the input commands of the rider. The processor uses the sensor signals to determine and transmit the appropriate command to the motor amplifiers. The information transmitted to the processors by the sensors include the spatial orientation of the transporter provided by an inertial measurement unit (IMU) 181, 182, the rider directed turn command provided by a yaw input device (YID) 132, 142, and the presence of a rider on the transporter provided by a rider detector (RD) 161, 162, 163, 164. Other inputs to the processor may include a rider operated pitch trim device (PTD) 148 for adjusting the pitch of the transporter to a more comfortable pitch and a stop button (not shown) for bringing the transporter to a stop quickly. Depending on the importance of the sensor to the operation of the transporter, the sensors may or may not be duplicated for redundancy. For example, the spatial orientation of the transporter is central to the operation of the transporter, as is described below, and therefore an A-group IMU 181 supplies transporter orientation information to the A processor 135 and a B-group IMU 182 supplies transporter orientation information to the B-processor 145. On the other hand, the transporter may still be operated in a safe manner without the PTD 148 so only one such device is typically provided. Similarly, an output device such as a display 138 does not require redundancy. A non-redundant device such as a display 138 or a PTD 148 may be connected to either processor.

In the embodiment depicted in FIG. 2, display 138 is controlled by the A processor 136 and the PTD 148 is in direct signal communication with the B processor 145. The information provided by the PTD 148 is transmitted by the B processor 145 to the A processor 135 via the B channel 147.

Additionally, each processor 135, 145 communicates with one of the user interface processors (UIPs) 173, 174. Each UIP 173, 174 receives steering commands from the user through one of the yaw input devices 171, 172. A A-group UIP 173 also communicates to the non-redundant UIDs such as the display 138, brake switch 175, and pitch trim control 148. Other user interface devices that are not provided redundantly in the embodiment shown in FIG. 2, such as a sound warning device, lights, and an on/off switch, may also be connected to the A-group UIP 173. The A-group UIP 173 may also pass along information provided by the user interface devices to the B-group UIP 174.

In accordance with preferred embodiments of the invention, the A-group UIP 173 compares calculations of the A-group processor with calculations of the B-group processor and queries the A-group processor 135 with a `watchdog` calculation to verify operation of the A-group processor. Similarly, the B-group UIP 174 queries the B-group processor 145 to verify normal operation of the B-group processor.

Several components of personal transporter 10, in accordance with various embodiments of the present invention, are now described.

Battery

The transporter power required to drive the motors 110, 120 and electrical components may be supplied by any known source of electrical power known in the electrical arts. Sources of power may include, for example, both internal and external combustion engines, fuel cells, and rechargeable batteries. In preferred embodiments of the present invention, power supplies 131, 141 are rechargeable battery packs. Various battery chemistry modalities may be used, as preferred under various conditions, and may include, without limitation, lead-acid, Lithium-ion, Nickel-Cadmium (Ni--Cd), or Nickel-metal hydride (Ni-MH) chemistry. Each power supply 131, 141 is enclosed in a container that protects the battery packs and associated electronics from the environment.

FIG. 3 shows a top view of one embodiment of the power supply with the top cover removed. A tray 205 that is covered and sealed to protect the contents from the environment encloses the components of power supply 200. Tray 205 houses a plurality of battery blocks 210, each of which contains a plurality of battery cells 215. The number of cells 215 packaged in a block 210 and the total number of blocks in the power supply are determined by the expected power requirements of the transporter. In a preferred embodiment, cells 215 are "sub-C"-size cells and each block 210 contains ten cells 215. In another embodiments, block 210 may contains other numbers of cells 215. Cells 215 are preferably connected in series, as are blocks 210. In other embodiments blocks 210 may be connected in parallel with the cells 215 within each block connected in series, or, alternatively, blocks 210 may be connected in series with the cells 215 within each block 210 connected in parallel, each configuration providing advantages for particular applications.

Electrical current flowing into or out of power supply 200 is conducted through a connector 220 that provides the electrical interface between the power supply 200 and the transporter 10. In an embodiment shown in FIG. 3, connector 220 is located on the top cover (not shown) of power supply 200 but any positioning of connector 220 is within the scope of the present invention. In addition to conducting current into or out of power supply 200, connector 220 may also include a plurality of signal lines that establish signal communication between the power supply internals and any other transporter processor.

The temperature of each block 210 is monitored by the supply controller 230 through temperature sensors 235. In addition, supply controller 230 also monitors the voltage of each block 210. If supply controller 230 detects that the temperature of a block 210 is over a preset temperature limit, the supply controller 230 sends an over-temperature signal to the processor through connector 220. Similarly, if supply controller 230 detects that the voltage of a block 210 is below a preset voltage limit, the supply controller 230 sends an under-voltage signal to the processor through the connector 220.

Supply controller 230 preferably contains an ID chip 240 that stores information about the power supply such as battery type, the number of cells in the power supply 210, and optionally, a date code or serial number code. The ID chip 240 may be of any type of permanent or semi-permanent memory devices known in the electronics art. The information contained in the ID chip 240 may be used by the processor 135, 145 to set various operating parameters of the transporter. The information may also be used by a charger (not shown) to recharge the power supply.

Power supply 200 may be connected via connector 220 to a charger that is either external to the transporter or contained within the transporter. In one embodiment of the present invention, the charger is located on the transporter and is an AC switch mode charger well known in the power art. In another embodiment, the charger is contained within battery tray 205. In another embodiment of the present invention, power supply 200 is charged by an auxiliary power unit (APU) such as the one described in copending U.S. patent application, Ser. No. 09/517,808 entitled "Auxiliary Power Unit".

Motor Amplifier & Operating Modes

FIG. 4 shows a block schematic of a power module 300 of one embodiment of the present invention. A balancing processor 310 generates a command signal to motor amplifier 320 that, in turn, applies the appropriate power to motor 330. Balancing processor 310 receives inputs from the user and system sensors and applies a control law, as discussed in detail below, to maintain balance and to govern