Speed limiting for a balancing transporter

• US 6,874,591 B2
• Filed: 06/13/2003
• Issued: 04/05/2005
• Est. Priority Date: 05/27/1994
• Status: Expired due to Term

• Current Assignee: Deka Products Limited Partnership
• Original Assignee: Deka Products Limited Partnership
• Inventors: Morrell, John B., Robinson, David W.
• Primary Examiner(s): Morris, Lesley D.
• Assistant Examiner(s): LUBY, MATTHEW D
• Application Number:
  US10/460,970
• Publication Number:
  US 20030231022A1
• Time in Patent Office: 662 Days
• Field of Search: 324426-432, 180/171, 180/179, 180/7.1, 701/29, 701/36, 701/51, 702/63, 702/64
• US Class Current: 180/179
• CPC Class Codes: A61G 5/065 with three or more wheels mounted on a rotary cross member, e.g. spiders or spoked wheels with small wheels at the end of the spokes
• CPC Class Codes: A63C 17/12 with driving mechanisms
• CPC Class Codes: B60K 7/00 Disposition of motor in, or adjacent to, traction wheel roller-skate driving mechanisms A63C17/12
• CPC Class Codes: B60L 15/2045 for optimising the use of energy
• CPC Class Codes: B60L 2200/16 Single-axle vehicles
• CPC Class Codes: B60L 2200/24 Personal mobility vehicles
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 2240/18 lateral
• CPC Class Codes: B60L 2240/20 angular
• CPC Class Codes: B60L 2240/22 Yaw angle
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/461 Speed
• CPC Class Codes: B60L 2240/463 Torque
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/549 Current
• CPC Class Codes: B60L 58/10 for monitoring or controlling batteries
• CPC Class Codes: B62D 57/00 Vehicles characterised by having other propulsion or other ground- engaging means than wheels or endless track, alone or in addition to wheels or endless track sledges B62B; motor sledges B62M
• CPC Class Codes: B62K 1/00 Unicycles
• CPC Class Codes: B62K 11/007 Automatic balancing machines with single main ground engaging wheel or coaxial wheels supporting a rider
• CPC Class Codes: B62K 17/00 Cycles not otherwise provided for
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility

Abstract

A class of transporters for carrying an individual over ground having a surface that may be irregular. Various embodiments have a motorized drive, mounted to the ground-contacting module that causes operation of the transporter in an operating position that is unstable with respect to tipping when the motorized drive arrangement is not powered. Related methods are provided for determining the maximum operating speed of the transporter from measurement of battery parameters and transporter motor current and for limiting the speed of the transporter to maintain stability.

Claims

1. A method for estimating an instantaneous capability of a battery, the battery characterized by an open circuit voltage and an internal resistance, the method comprising:

a. measuring battery parameters to obtain values of the battery parameters including a voltage value and a current value;

b. repeating measurements to obtain successive values of the battery parameters; and

c. filtering the successive values of the battery parameters to estimate the instantaneous capability of the battery.

2. A method according to claim 1 wherein filtering the successive values of the battery parameters includes performing a statistical analysis of the successive values.

3. A method according to claim 1, wherein filtering the successive values of the battery parameters includes performing recursive least squares regression.

4. A method according to claim 1, wherein filtering the measured battery parameters includes performing a recursive least squares regression with exponential forgetting.

5. A method for estimating an instantaneous capability of a battery, the battery characterized by an open circuit voltage and an internal resistance, the method comprising:

a. measuring battery parameters to obtain values including a voltage value and a current value;

b. repeating measurements to obtain successive values of the battery parameters; and

c. statistically analyzing the successive values of the battery parameters to estimate the instantaneous capability of the battery.

6. A method for determining a maximum operating speed for a transporter, the transporter including a battery supplying power to a motor, the battery characterized by a battery voltage, an open circuit voltage and an internal resistance, the motor propelling the transporter, the motor characterized by an average motor current, the method comprising:

a. calculating an open circuit voltage estimate and an internal resistance estimate for the battery; and

b. calculating the maximum operating speed as a function of the open circuit voltage estimate and the internal resistance estimate for the battery and the average motor current.

7. A method according to claim 6, wherein the function is a linear function of the open circuit voltage estimate, the internal resistance estimate for the battery and the average motor current.

8. A transporter for carrying a payload including a user, the transporter comprising:

a. a platform for supporting the user;

b. a ground-contacting module, coupled to the platform for propelling the transporter over an underlying surface in motion characterized by a speed;

c. a motorized drive arrangement, the drive arrangement, ground-contacting module and payload comprising a system being unstable with respect to tipping in a fore-aft plane when the motorized drive is not powered, the motorized drive arrangement causing, when powered, automatically balanced operation of the system;

d. a power source characterized by an instantaneous capability to energize the motorized drive arrangement; and

e. a governor that limits the speed of the ground-contacting module based at least on the instantaneous capability of the power source.

9. A transporter according to claim 8, wherein the motorized drive arrangement is characterized by an average motor current and wherein the maximum operating speed is a function of the average motor current.

10. A transporter according to claim 9, further comprising a monitor, coupled to the motorized drive arrangement, the monitor including logic for calculating a maximum operating speed as a function of a battery open circuit voltage estimate, a battery internal resistance estimate and the average motor current.

11. A transporter according to claim 10, wherein the function is a linear function of the battery open circuit voltage and internal resistance and the average motor current.

12. A method for limiting the speed of a transporter, the method comprising:

a. providing a transporter including;

i) a platform which supports a payload including the user,

ii) a ground-contacting module, mounted to the platform, including at least one ground-contacting member, characterized by a ground contact region and a fore-aft plane,

iii) a motorized drive arrangement, coupled to the ground-contacting module, the drive arrangement, ground-contacting module and payload constituting a system being unstable with respect to tipping in at least the fore-aft plane when the motorized drive is not powered, the system characterized by a system speed and a system pitch value, and

iv) an energy storage device, characterized by a instantaneous capability, powering the drive arrangement;

b. determining the instantaneous capability of the energy storage device; and

c. limiting operation of the motorized drive arrangement on the basis, at least, of the instantaneous capability of the energy storage device.

13. A method according to claim 12, further including

d. dynamically maintaining stability of the system in the fore-aft plane by operation of the drive arrangement so that the net torque experienced by the system about ground contact region causes a specified acceleration of the system.

14. A method according to claim 13, wherein the step of dynamically maintaining stability includes applying a contribution to the net torque that is a function of a system pitch value multiplied by a gain.

15. A method according to claim 14, further including:

e. calculating a pitch modification value based at least on the instantaneous capability of the energy storage device; and

f. adding the pitch modification value to the system pitch value in such a manner as to limit the system speed when the system speed exceeds an intervention speed.

16. A method according to claim 15, further including:

g. subtracting the pitch modification value from the system pitch value when the system speed falls below a drop-out value.

17. A method according to claim 16 wherein subtracting the pitch modification includes subtracting the modification incrementally.

18. A method according to claim 15, wherein calculating a pitch modification includes adding a proportional term contribution, where the proportional term contribution is a function of the difference between the system speed and the intervention speed.

19. A method according to claim 18, wherein calculating a pitch modification includes adding a derivative term contribution to the pitch modification, where the derivative term contribution is a function of a system acceleration.

20. A method according to claim 19, wherein calculating a pitch modification includes adding an integral term contribution to the pitch modification, the integral term contribution formed by:

i) multiplying a gain by the difference between the system speed and a speed limit, and

ii) adding a previous integral term contribution.

21. A method according to claim 15, wherein the intervention speed is a function of the direction of system velocity.

22. A method according to claim 15, wherein the energy storage device is a battery and the transporter further includes a capability to regenerate the battery from the motorized drive arrangement, the battery further characterized by an over voltage threshold and an over voltage range, wherein the intervention speed is reduced as a function of an over voltage difference between the battery voltage and the over voltage threshold.

23. A method according to claim 22 wherein the function of the over voltage difference is a linear function of the over voltage difference when the battery voltage is within the over voltage range and a constant when the battery voltage exceeds the over voltage range.

24. A transporter for carrying a payload including a user, the transporter comprising:

a. a platform which supports a payload including the user;

b. a ground-contacting module, mounted to the platform, including at least one ground-contacting member, characterized by a ground contact region and a fore-aft plane;

c. a motorized drive arrangement, coupled to the ground-contacting module, the drive arrangement, ground-contacting module and payload constituting a system being unstable with respect to tipping in at least the fore-aft plane when the motorized drive is not powered, the system characterized by a system speed, and a system pitch value;

d. an energy storage device, characterized by a instantaneous capability, powering the drive arrangement; and

e. a controller including;

i) a control loop in which the drive arrangement is included, for dynamically maintaining stability of the system in the fore-aft plane by operation of the drive arrangement so that the net torque experienced by the system about the region of contact with the ground causes a specified acceleration of the system, the net torque including a contribution that is a function of the system pitch value multiplied by a gain, and

ii) logic that determines the instantaneous capability of the energy storage device; and

iii) logic that limits operation of the motorized drive arrangement on the basis, at least, of the instantaneous capability of the energy storage device.

25. A transporter according to claim 24, wherein the logic that limits operation of the motorized drive arrangement includes logic that:

a. calculates a pitch modification value based at least on the instantaneous capability of the energy storage device; and

b. adds the pitch modification value to the system pitch value in such a manner as to limit the system speed when the system speed exceeds an intervention speed.

26. A transporter according to claim 25, wherein the energy storage device is a battery.

27. A transporter according to claim 26, wherein the transporter further includes a capability to regenerate the battery from energy derived from the motorized drive arrangement, the battery further characterized by a battery voltage, an over voltage threshold and an over voltage range, wherein the intervention speed is reduced as a function of an over voltage difference between the battery voltage and the over voltage threshold.

28. A transporter according to claim 27, wherein the function is a linear function of the over voltage difference when the battery voltage is within the over voltage range and a constant when the battery voltage exceeds the over voltage range.