Vehicle dynamics control in electric drive vehicles

• US 8,718,897 B2
• Filed: 03/24/2011
• Issued: 05/06/2014
• Est. Priority Date: 03/29/2010
• Status: Active Grant

• Current Assignee: Wrightspeed, Inc.
• Original Assignee: Wrightspeed, Inc.
• Inventors: Wright, Ian, Cash, Ryan
• Primary Examiner(s): Olszewski, John R
• Assistant Examiner(s): MELTON, TODD M
• Application Number:
  US13/071,356
• Publication Number:
  US 20110238251A1
• Time in Patent Office: 1,139 Days
• Field of Search: 701/22, 180/6.48, 180/65.1, 180/65.51, 180/197
• US Class Current: 701/89
• CPC Class Codes: B60K 7/0007 the motor being electric
• CPC Class Codes: B60L 15/20 for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
• CPC Class Codes: B60L 15/2036 Electric differentials, e.g. for supporting steering vehicles
• CPC Class Codes: B60L 15/2054 by controlling transmissions or clutches
• CPC Class Codes: B60L 15/32 Control or regulation of multiple-unit electrically-propelled vehicles
• CPC Class Codes: B60L 2220/44 Wheel Hub motors, i.e. integrated in the wheel hub
• CPC Class Codes: B60L 2220/46 Wheel motors, i.e. motor connected to only one wheel
• CPC Class Codes: B60L 2240/461 Speed
• CPC Class Codes: B60L 2240/465 Slip
• CPC Class Codes: B60L 3/102 of individual wheels
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 2520/26 Wheel slip
• CPC Class Codes: B60W 2720/26 Wheel slip
• CPC Class Codes: B60W 30/18172 Preventing, or responsive to skidding of wheels
• CPC Class Codes: B60W 50/087 where the control system corrects or modifies a request from the driver
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

Embodiments of the invention are directed toward a geared traction drive system configured to drive a wheel of a vehicle, comprising: a driveshaft for transmitting power to the wheel; an electric drive motor for driving the driveshaft, the electric drive motor configured to receive signals from a vehicle dynamic control system to command a required speed; a gear reduction component for reducing the speed of the motor by a predetermined factor to a lower speed suitable for driving the wheel; and a drive electronics component that works with the electric drive motor to drive the wheel to the speed commanded by the vehicle dynamic control system.

Claims

1. A vehicle dynamics control system, comprising:

a first motor electrically coupled to a first drive electronics module, the first motor coupled to a first wheel, and a second motor electrically coupled to a second electronics module, the second motor coupled to a second wheel; and

a main control processor, the main control processor configured to control the electric motors by transmitting speed commands to the drive electronics modules, wherein the transmitted speed commands are determined by;

receiving vehicle speed and direction data from at least one sensor,

receiving driver data from at least one driver input sensor,

generating first and second required wheel speeds from the driver data and the vehicle speed and direction data,

calculating first and second optimum wheel speeds, the calculated optimum wheel speeds being the speed at which each wheel can be driven to so as to not exceed a slip rate which achieves an optimal slip,

determining a first and second commanded wheel speed by limiting the first and second required wheel speeds to the optimum wheel speeds, and

transmitting the first and second commanded wheel speeds to the first and second drive electronics modules.

2. The vehicle dynamics control system of claim 1, wherein the main control processor includes a non-transitory computer readable medium having computer executable program code embodied thereon, the computer executable program code configured to receive the sensor inputs, calculate required wheel speed, and send appropriate signals to the electric drive motor to command the required wheel speed.

3. The vehicle dynamics control system of claim 1, wherein the main control processor includes a dedicated general purpose microcomputer with flash memory main storage, RAM, and communications ports to interface to the at least one driver in-put sensor.

4. The vehicle dynamics control system of claim 1, wherein the vehicle dynamics control system main control processor is configured to calculate effective tire circumference, tire pressure, vehicle mass and location of center of gravity, tire slip rate, and tire slip angle.

5. The vehicle dynamics control system of claim 1, wherein the first commanded wheel speed and the second commanded wheel speed are different when the vehicle is cornering.

6. The vehicle dynamics control system of claim 1, further including a third motor electrically coupled to a third electronics drive module, the third motor coupled to a third wheel, and a fourth motor electrically coupled to a fourth electronics drive module, the fourth motor coupled to a fourth wheel.

7. The vehicle dynamics control system of claim 6, wherein the main control processor is further configured to control the third and fourth electric motors by transmitting third and fourth speed commands to the third and fourth drive electronics modules, wherein the third and fourth speed commands are determined by:

receiving vehicle speed and direction data from at least one sensor, receiving driver data from at least one driver input sensor, generating third and fourth required wheel speeds from the driver data and the vehicle speed and direction data, calculating third and fourth optimum wheel speeds, the calculated optimum wheel speeds being the speed at which each wheel can be driven to so as to not exceed a slip rate which achieves an optimal slip, determining a third and fourth commanded wheel speed by limiting the third and fourth required wheel speeds to the optimum wheel speeds, and transmitting the third and fourth commanded wheel speeds to the third and fourth drive electronics modules.

8. The vehicle dynamics control system of claim 7, wherein the first, second, third and fourth commanded wheel speeds are different.

9. The vehicle dynamics control system of claim 7, wherein the first and third wheel commanded speeds are equal.

10. The vehicle dynamics control system of claim 7, wherein the second and fourth commanded wheel speeds are equal.

11. The vehicle dynamics control system of claim 7, wherein the first, second, third and fourth commanded wheel speeds are equal.

12. The vehicle dynamics control system of claim 7, wherein vehicle direction is further controlled by altering wheel speeds to achieve a desired directional change.

13. The vehicle dynamics control system of claim 1, wherein the driver input sensor is a steering angle sensor.

14. The vehicle dynamics control system of claim 13, further including a second driver input sensor, wherein the second driver input sensor is an accelerator position sensor.

15. The vehicle dynamics control system of claim 1, wherein the driver input sensor is an accelerator position sensor.

16. The vehicle dynamics control system of claim 1, wherein the vehicle speed and direction are measured using a velocity sensor.

17. The vehicle dynamics control system of claim 16, wherein the velocity sensor is a digital camera disposed perpendicular to a road surface.

18. The vehicle dynamics control system of claim 1, wherein the vehicle speed and direction are measured using two velocity sensors.

19. The vehicle dynamics control system of claim 18, wherein the velocity sensors are mounted at opposite ends of the vehicle.

20. The vehicle dynamics control system of claim 19, wherein the velocity sensors are digital cameras disposed perpendicular to the road surface.

21. The vehicle dynamics control system of claim 1, wherein the slip includes a slip rate and a slip angle the slip rate and slip angle being expressed as a vector sum.

22. The vehicle dynamics control system of claim 21, wherein the main control processor maintains the vehicle within a traction circle through the commanded wheel speeds, the traction circle consisting of a collection of points defined by the vector sum of the slip angle and slip rate defining a maximum traction force in each direction.

23. The vehicle dynamics control system of claim 21, wherein the main control processor prevents wheelspin through the commanded wheel speeds.

24. The vehicle dynamics control system of claim 1, wherein the driver input sensor is selected from a group consisting of a brake pressure sensor, a steering sensor, or an accelerator position sensor.

25. The vehicle dynamics control system of claim 1, further including a display electronically coupled to the main control processor, the display configured to display at least one of the following, vehicle speed, slip rate, slip angle, differential torque, traction circle calculation, steering angle, accelerator position, brake position, used traction vs. available traction, motor speed.

26. The vehicle dynamics control system of claim 1, further including a second driver input sensor, the second driver sensor including a unique driver identifier.

27. The vehicle dynamics control system of claim 26, wherein the unique driver identifier selects a unique program stored within the main control processor.

28. The vehicle dynamics control system of claim 27, wherein the unique program is a valet program, the valet program limiting the vehicle speed and acceleration.

29. The vehicle dynamics control system of claim 27, wherein the unique program is an advanced driver program, the advanced driver program altering one or more program parameter selected from the group consisting of:

greater wheel slip, greater acceleration or greater torque application.

30. The vehicle dynamics control system of claim 1, wherein the main control processor prevents vehicle rollover by altering the first and second commanded wheel speeds.

31. A method for controlling vehicle dynamics, comprising:

receiving vehicle speed and direction data from at least one sensor on a vehicle;

receiving driver data from at least one driver input sensor;

generating, by at least one computer, a first and a second required wheel speed from the driver data and the vehicle speed and direction data;

calculating, by at least one computer, a first and a second optimum wheel speed, the calculated optimum wheel speed being the speed at which respectively a first and a second wheel can be driven to so as to not exceed a slip rate which achieves an optimal slip over a surface;

determining, by at least computer, a first and a second commanded wheel speed by limiting the first and the second required wheel speed to respectively the first and the second calculated optimum wheel speed;

transmitting the first commanded wheel speed to a first electronic module coupled with a first motor, the first motor coupled to the first wheel; and

transmitting the second commanded wheel speed to a second electronic module coupled with a second motor, the second motor coupled with the second wheel.

32. The method of claim 31, wherein the first commanded wheel speed and the second commanded wheel speed are different when the vehicle is cornering.

33. The vehicle dynamics control system of claim 31, further comprising:

generating, by at least one computer, a third and a fourth required wheel speed from the driver data and the vehicle speed and direction data;

calculating, by at least one computer, a third and a fourth optimum wheel speeds, the third and the fourth calculated optimum wheel speed being the speed at which respectively a third wheel and a fourth wheel can be driven to so as to not exceed a slip rate which achieves an optimal slip over the surface, determining, by at least one computer, a third and a fourth commanded wheel speed by limiting the third and the fourth required wheel speed to respectively the third and the fourth optimum wheel speed; and

transmitting the third commanded wheel speed to a third electronic module coupled with a third motor, the third motor coupled to the third wheel; and

transmitting the fourth commanded wheel speed to a fourth electronic module coupled with a fourth motor, the fourth motor coupled with the fourth wheel.

34. The method of claim 33, wherein the first, second, third and fourth commanded wheel speeds are different.

35. The vehicle dynamics control system of claim 33, wherein the first and third wheel commanded speeds are equal.

36. The vehicle dynamics control system of claim 33, wherein the second and fourth commanded wheel speeds are equal.

37. The vehicle dynamics control system of claim 33, wherein the first, second, third and fourth commanded wheel speeds are equal.

38. The method of claim 31, wherein the slip includes a slip rate and a slip angle the slip rate and slip angle being expressed as a vector sum.

39. The method of claim 38, further comprises maintaining, through at least one computer, the vehicle within a traction circle through the commanded wheel speeds, the traction circle comprising a collection of points defined by the vector sum of the slip angle and slip rate defining a maximum traction force in each direction.

40. The vehicle dynamics control system of claim 38, further comprising preventing, by at least one processor, wheelspin through the commanded wheel speeds.

41. The method of claim 31, wherein the driver input sensor is selected from a group consisting of a brake pressure sensor, a steering sensor, or an accelerator position sensor.