Torque steer mitigation

1 . A system for a mitigating torque steer in a vehicle, the system comprising:

a plurality of vehicle sensors configured to sense data related to a vehicle steering system that includes a motor and a steering rack, a left wheel, and a right wheel; and

an electronic processor communicatively connected to the plurality of vehicle sensors and configured to

detect an occurrence of torque steering by:

generating a left wheel torque model and a right wheel torque model for the vehicle,

determining a first moment about the z-axis with respect to the left wheel of the vehicle (Mz_left) using the left wheel torque model,

determining a second moment about the z-axis with respect to the right wheel of the vehicle (Mz_right) using the right wheel torque model,

determining a steering torque as a sum of the first moment Mz_left and the second moment Mz_right,

detecting the occurrence of torque steering based on a difference between the first moment Mz_left and the second moment Mz_right,

in response to detecting an occurrence of torque steering, determine a compensation torque for the vehicle as a function of the steering torque and a gear ratio of the motor, and

control the motor based on the compensation torque.

2 . The system of claim 1 , wherein the right wheel torque model is a front right wheel torque model and the left wheel torque model is a front left wheel torque model.

3 . The system of claim 1 , wherein the electronic processor controls the motor based the compensation torque by applying the compensation torque as a motor torque.

4 . The system of claim 1 , wherein the electronic processor controls the motor based on the compensation torque by applying the compensation torque as a handwheel torque.

5 . The system of claim 1 , wherein the electronic processor is configured to detect the occurrence of torque steering in response to detecting a vehicle acceleration or a vehicle deceleration.

6 . The system of claim 5 , wherein the vehicle deceleration includes a regenerative braking operation.

7 . The system of claim 1 , wherein the electronic processor is configured to generate the right wheel torque model and the left wheel torque model based on a first left wheel geometric steering offset (dy_left) of a left tire point of rotation relative to a left tire contact patch center, a second left wheel geometric steering offset (dx_left) of a left tire point of rotation relative to a left tire contact patch center, a first right wheel geometric steering offset (dy_right) of a right tire point of rotation relative to a right tire contact patch center, a second right wheel geometric steering offset (dx_right) of a right tire point of rotation relative to a right tire contact patch center, a left wheel normal force (f_normL), a right wheel normal force (f_normR), a left wheel lateral force (f_latL), a right wheel lateral force (f_latR), a left wheel longitudinal force (f_longL), and a right wheel longitudinal force (f_longR).

8 . The system of claim 7 , wherein the electronic processor is configured to determine the first moment Mz_left according to an equation:

Mz _left=(( dy _left* f _long L )+( dx _left* f _lat L ))* f _norm L.

9 . The system of claim 7 , wherein the electronic processor is configured to determine the second moment Mz_right according to an equation:

Mz _right=(( dy _right* f _long R )+( dx _right* f _lat R ))* f _norm R.

10 . The system of claim 7 , wherein the electronic processor is configured to determine each geometric steering offset based on a rack position of the steering rack and a heave of the vehicle.

11 . The system of claim 7 , wherein the electronic processor is configured to determine each longitudinal force as a difference between a braking force of the vehicle and a motor force of the vehicle.

12 . The system of claim 11 , wherein the electronic processor is configured to determine each longitudinal force further based on a longitudinal slip of the vehicle.

13 . The system of claim 7 , wherein the electronic processor is configured to determine each lateral force based on a lateral slip of the vehicle.

14 . The system of claim 7 , wherein the electronic processor is configured to determine each normal force using a lookup table.

15 . A method for mitigating torque steer in a vehicle, the method comprising:

detecting an occurrence of torque steering by:

generating a left wheel torque model and a right wheel torque model for the vehicle,

determining a first moment about the z-axis with respect to a left wheel of the vehicle (Mz_left) using the left wheel torque model,

determining a second moment about the z-axis with respect to a right wheel of the vehicle (Mz_right) using the right wheel torque model,

determining a steering torque as a sum of the first moment Mz_left and the second moment Mz_right,

detecting the occurrence of torque steering based on a difference between the first moment Mz_left and the second moment Mz_right;

in response to detecting an occurrence of torque steering, determining a compensation torque for the vehicle as a function of the steering torque and a gear ratio of the motor; and

controlling the motor based on the compensation torque.

16 . The method of claim 15 , wherein the right wheel torque model is a front right wheel torque model and the left wheel torque model is a front left wheel torque model.

17 . The method of claim 15 , wherein controlling the motor based the compensation torque includes applying the compensation torque as a motor torque.

18 . The method of claim 15 , wherein controlling the motor based on the compensation torque includes applying the compensation torque as a handwheel torque.

19 . The method of claim 15 , wherein detecting the occurrence of torque steering is performed in response to detecting a vehicle acceleration or a vehicle deceleration.

20 . The method of claim 19 , wherein the vehicle deceleration includes a regenerative braking operation.