SYSTEMS AND METHODS FOR DETERMINING ROAD MU AND DRIVE FORCE

• US 20130138318A1
• Filed: 11/28/2011
• Published: 05/30/2013
• Est. Priority Date: 11/28/2011
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Motor Engineering & Manufacturing North America Incorporated (Toyota Motor Corporation)
• Inventors: Choby, Jordan
• Granted Patent: US 8,706,378 B2
• Time in Patent Office: Days
• US Class Current: 701/84
• CPC Class Codes: B60T 2270/86 Optimizing braking by using ESP vehicle or tire model
• CPC Class Codes: B60T 8/172 Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters B60T8/17551 takes precedence
• CPC Class Codes: B60T 8/175 Brake regulation specially adapted to prevent excessive wheel spin during vehicle acceleration, e.g. for traction control safety devices for propulsion unit control responsive to, or preventing, skidding of wheels B60K28/16

Abstract

The vehicle described herein employs a mu logic module. The mu logic module monitors vehicle operating conditions, and based on those operating conditions determines a road surface mu in response to a wheel slip event. The road surface mu is then used to determine a drive force to minimize or control the wheel slip event. The mu logic module continually monitors and adjusts the drive force provided to at least one of the wheels to maximize the applied drive force, while stabilizing and controlling wheel slip events to ensure safe operation of a vehicle.

Claims

1. An automobile, comprising:

a body;

a chassis configured to couple to a support of the body;

a plurality of wheels rotatably coupled to the chassis;

an engine configured to drive at least one of the plurality of wheels and is at least partially enclosed by the body;

a steering wheel configured to communicate driver inputs to the plurality of wheels;

an accelerator configured to communicate driver inputs to the engine;

a sensor configured to monitor at least one of the plurality of wheels and detect a first slip condition of the at least one of the plurality of wheels; and

an electronic control unit capable of receiving data from the sensor, managing the operation of the engine, calculating a first drive force based on a tractive force model in response to the sensor detecting a first slip condition, and increasing the first drive force based on the tractive force model to a second drive force.

2. The automobile of claim 1, wherein the sensor continues to monitor the at least one of the plurality of wheels in response to the first slip condition to detect a second slip condition.

3. The automobile of claim 2, wherein the electronic control unit reduces the second drive force to a third drive force in response to the second slip condition.

4. The automobile of claim 3, wherein the third drive force is determined based on the tractive force model.

5. The automobile of claim 1, wherein the first slip condition is detected when the automobile is in at least one of a drive gear and a reverse gear.

6. The automobile of claim 1, wherein the electronic control unit is configured to approximate a mu value of the road in response to vehicle operating conditions.

7. The automobile of claim 6, wherein the first drive force is determined as a function of the approximate mu value of the road.

8. The automobile of claim 1, wherein a mass of the automobile is used to determine the first tractive force.

9. The automobile of claim 1, wherein the tractive force model is employed by the electronic control unit in response to a first slip condition when the vehicle is operating within a predetermined speed range.

10. A method, comprising:

providing an automobile with a sensor, a plurality of wheels, and an electronic control unit, wherein the electronic control unit has a mu control including a speed threshold and a tractive force model;

detecting a first slip condition at one of the plurality of wheels by the sensor;

comparing the operating speed of the automobile to the speed threshold;

calculating, by the electronic control unit, a first drive force in response to the first slip condition;

reducing power provided to at least one of the plurality of wheels to achieve the first drive force;

monitoring the plurality of wheels by the sensor;

increasing the first drive force provided to at least one of the plurality of wheels;

calculating, by the electronic control unit, a second drive force based on the increase in the first drive force and the tractive force model in response to detecting a second slip condition at the at least one of the plurality of wheels by the sensor; and

adjusting power provided to the at least one of the plurality of wheels to achieve the second drive force in response to the electronic control unit calculating a second drive force.

11. The method of claim 10, wherein the tractive force is a function of a mass of the automobile.

12. The method of claim 11, wherein the tractive force is a function of the mass and a road surface mu.

13. The method of claim 11, wherein the mass is a function of road grade.

14. The method of claim 11, wherein the first slip condition is detected by comparing an actual acceleration rate of the at least one of the plurality of wheels to an expected acceleration rate of the at least one of the plurality of wheels.

15. The method of claim 14, wherein the expected acceleration rate is a function of the mass of the automobile, a road grade and a drive force being created.

16. The method of claim 11, further comprising estimating a road surface mu.

17. The method of claim 16, wherein the road surface is mu is estimated by detecting an initial drive force at substantially the same time of the first slip condition.

18. An automobile, comprising:

a plurality of wheels;

an engine configured to provide a first drive force to at least one of the plurality of wheels; and

an electronic control unit comprising a mu drive-force model is in communication with the engine and configured to detect a slip condition of at least one of the plurality of wheels and estimate an applied drive force at the at least one of the plurality of wheels in response to the slip condition such that the first drive force is estimated at substantially the same time that the slip condition occurs, to estimate a road mu based on the first drive force, and to calculate and communicate a second drive force to the engine such that power to the at least one of the plurality of wheels is reduced to a level that produces the second drive force.

19. The automobile of claim 18, wherein the mu drive-force model is configured to determine the second drive force based on the estimated road mu and a mass of the automobile.

20. The automobile of claim 18, wherein the mu drive-force model is engaged in response to a snow mode setting being selected.