DYNAMIC REGENERATIVE BRAKING TORQUE CONTROL

1 . A method for adjusting regenerative braking torque in a vehicle having wheels and a regenerative braking system providing the regenerative braking torque, the method comprising the steps of:

determining a deceleration of the vehicle;

determining a wheel slip of the wheels; and

adjusting the regenerative braking torque for the regenerative braking system, via a processor, using the deceleration and the wheel slip.

2 . The method of claim 1 , wherein:

the wheels comprise front wheels and rear wheels;

the step of determining the wheel slip comprises the step of determining a relative wheel slip between the front wheels and the rear wheels; and

the step of adjusting the regenerative braking torque comprises the step of adjusting the regenerative braking torque using the deceleration and the relative wheel slip.

3 . The method of claim 2 , wherein the step of adjusting the regenerative braking torque comprises the step of determining an adjustment for the regenerative braking torque using the deceleration, the relative wheel slip, and a look-up table relating the deceleration, the relative wheel slip, and the adjustment.

4 . The method of claim 2 , wherein the step of adjusting the regenerative braking torque comprises the step of reducing the regenerative braking torque from a first non-zero amount to a second non-zero amount as the relative wheel slip increases for a given value of the deceleration, provided that the relative wheel slip is greater than a predetermined threshold.

5 . The method of claim 2 , wherein the step of adjusting the regenerative braking torque comprises the step of reducing the regenerative braking torque from a first non-zero amount to a second non-zero amount as the deceleration increases for a given value of the relative wheel slip, provided that the deceleration is greater than a predetermined threshold.

6 . The method of claim 2 , wherein the step of determining the relative wheel slip comprises the steps of:

measuring front wheel speeds of the front wheels;

measuring rear wheel speeds of the rear wheels;

calculating a vehicle speed using the front wheel speeds and the rear wheel speeds;

calculating a front wheel slip of the front wheels using the front wheel speeds and the vehicle speed;

calculating a rear wheel slip of the rear wheels using the rear wheel speeds and the vehicle speed; and

calculating the relative wheel slip using the front wheel slip and the rear wheel slip.

7 . The method of claim 6 , wherein:

the step of calculating the front wheel slip comprises the step of calculating an average front wheel slip using the front wheel speeds and the vehicle speed;

the step of calculating the rear wheel slip comprises the step of calculating an average rear wheel slip using the rear wheel speeds and the vehicle speed; and

the step of calculating the relative wheel slip comprises the step of calculating an average relative wheel slip using the average front wheel slip and the average rear wheel slip.

8 . A program product for adjusting regenerative braking torque in a vehicle having wheels and a regenerative braking system providing the regenerative braking torque, the program product comprising:

a program configured to:

determine a deceleration of the vehicle;

determine a wheel slip of the wheels; and

adjust the regenerative braking torque for the regenerative braking system using the deceleration and the wheel slip; and

a non-transitory computer readable medium bearing the program and containing computer instructions stored therein for causing a computer processor to execute the program.

9 . The program product of claim 8 , wherein the wheels comprise front wheels and rear wheels, and the program is further configured to:

determine a relative wheel slip between the front wheels and the rear wheels; and

adjust the regenerative braking torque using the deceleration and the relative wheel slip.

10 . The program product of claim 9 , wherein the program is further configured to determine an adjustment for the regenerative braking torque using the deceleration, the relative wheel slip, and a look-up table relating the deceleration, the relative wheel slip, and the adjustment.

11 . The program product of claim 9 , wherein the program is further configured to reduce the regenerative braking torque from a first non-zero amount to a second non-zero amount as the relative wheel slip increases for a given value of the deceleration, provided that the relative wheel slip is greater than a predetermined threshold.

12 . The program product of claim 9 , wherein the program is further configured to reduce the regenerative braking torque from a first non-zero amount to a second non-zero amount as the deceleration increases for a given value of the relative wheel slip, provided that the deceleration is greater than a predetermined threshold.

13 . The program product of claim 9 , wherein the program is further configured to:

measure front wheel speeds of the front wheels;

measure rear wheel speeds of the rear wheels;

calculate a vehicle speed using the front wheel speeds and the rear wheel speeds;

calculate a front wheel slip of the front wheels using the front wheel speeds and the vehicle speed;

calculate a rear wheel slip of the rear wheels using the rear wheel speeds and the vehicle speed; and

calculate the relative wheel slip using the front wheel slip and the rear wheel slip.

14 . The program product of claim 13 , wherein the program is further configured to:

calculate an average front wheel slip using the front wheel speeds and the vehicle speed;

calculate an average rear wheel slip using the rear wheel speeds and the vehicle speed; and

calculate an average relative wheel slip using the average front wheel slip and the average rear wheel slip.

15 . A system for adjusting regenerative braking torque in a vehicle having wheels and a regenerative braking system providing the regenerative braking torque, the system comprising:

one or more sensors configured to measure a wheel speed of the wheels; and

a processor coupled to the one or more sensors and configured to:

determine a deceleration of the vehicle;

determine a wheel slip using the wheel speed; and

adjust the regenerative braking torque for the regenerative braking system using the deceleration and the wheel slip.

16 . The system of claim 15 , wherein:

the wheels comprise front wheels and rear wheels; and

the processor is further configured to:

determine a relative wheel slip between the front wheels and the rear wheels; and

adjust the regenerative braking torque using the deceleration and the relative wheel slip.

17 . The system of claim 16 , further comprising:

a memory configured to store a look-up table relating the deceleration, the relative wheel slip, and a desired adjustment for the regenerative braking torque, wherein the processor is further configured to determine an adjustment for the regenerative braking torque using the deceleration, the relative wheel slip, and the look-up table.

18 . The system of claim 16 , wherein:

the one or more sensors comprise:

one or more front wheel speed sensors configured to measure front wheel speeds of the front wheels;

one or more rear wheel speed sensors configured to measure rear wheel speeds of the rear wheels; and

the processor is further configured to:

calculate a vehicle speed using the front wheel speeds and the rear wheel speeds;

calculate a front wheel slip of the front wheels using the front wheel speeds and the vehicle speed;

calculate a rear wheel slip of the rear wheels using the rear wheel speeds and the vehicle speed; and

calculate the relative wheel slip using the front wheel slip and the rear wheel slip.

19 . The system of claim 18 , wherein the processor is further configured to calculate the deceleration using the vehicle speed.

20 . The system of claim 18 , wherein the processor is further configured to:

calculate an average front wheel slip using the front wheel speeds and the vehicle speed;

calculate an average rear wheel slip using the rear wheel speeds and the vehicle speed; and

calculate an average relative wheel slip using the average front wheel slip and the average rear wheel slip.