System and method of lane centering control with active rear steering

1 . A computer-implemented method that, when executed by data processing hardware, causes the data processing hardware to perform operations comprising:

determining a desired effective steering angle based on a desired path of a vehicle;

measuring a front road wheel angle and a rear road wheel angle, wherein the rear road wheel angle is a low resolution rear road wheel angle;

measuring a hand wheel angle;

estimating a high resolution rear road wheel angle using the low resolution rear road wheel angle, the hand wheel angle, and a predictive ratio;

determining an actual effective steering angle;

determining an effective steering angle error based on the desired effective steering angle and the actual effective steering angle;

generating a torque command for an electronic power steering system based on the effective steering angle error; and

controlling an active rear steering system independently from the electronic power steering system.

2 . The method of claim 1 , wherein determining the actual effective steering angle further comprises evaluating a difference between the front road wheel angle and the high resolution rear road wheel angle.

3 . The method of claim 1 , wherein determining the actual effective steering angle further comprises evaluating a difference between the front road wheel angle and the low resolution rear road wheel angle.

4 . The method of claim 1 , wherein determining the effective steering angle error further comprises determining a difference between the desired effective steering angle and the actual effective steering angle.

5 . The method of claim 1 , wherein the active rear steering system is configured to be selectively controlled while an advanced driver assistance system is enabled.

6 . The method of claim 5 , wherein controlling the active rear steering system further comprises disabling the active rear steering system if the advanced driver assistance system is enabled and either: (i) the rear road wheel angle is less than a first threshold or (ii) the vehicle has a velocity less than a second threshold.

7 . The method of claim 1 , further comprising adjusting the front road wheel angle of one or more front wheels of the vehicle based on the torque command.

8 . A system comprising:

data processing hardware; and

memory hardware in communication with the data processing hardware, the memory hardware storing instructions that, when executed on the data processing hardware, cause the data processing hardware to perform operations comprising:

determining a desired effective steering angle based on a desired path of a vehicle;

measuring a front road wheel angle and a rear road wheel angle, wherein the rear road wheel angle is a low resolution rear road wheel angle;

measuring a hand wheel angle;

estimating a high resolution rear road wheel angle using the low resolution rear road wheel angle, the hand wheel angle, and a predictive ratio;

determining an actual effective steering angle;

determining an effective steering angle error based on the desired effective steering angle and the actual effective steering angle;

generating a torque command for an electronic power steering system based on the effective steering angle error; and

controlling an active rear steering system independently from the electronic power steering system.

9 . The system of claim 8 , wherein determining the actual effective steering angle further comprises evaluating a difference between the front road wheel angle and the low resolution rear road wheel angle.

10 . The system of claim 8 , wherein determining the effective steering angle error further comprises determining a difference between the desired effective steering angle and the actual effective steering angle.

11 . The system of claim 8 , wherein controlling the active rear steering system further comprises disabling the active rear steering system if an advanced driver assistance system is enabled and either: (i) the rear road wheel angle is less than a first threshold or (ii) the vehicle has a velocity less than a second threshold.

12 . A vehicle management system comprising:

an advanced driver assistance system for maintaining control of a vehicle;

an active rear steering system, wherein the active rear steering system is disabled if the advanced driver assistance system is enabled and either: (i) a rear road wheel angle is less than a first threshold or (ii) the vehicle has a velocity less than a second threshold, and wherein a state of the active rear steering system is unchanged if the advanced driver assistance system is enabled and the rear road wheel angle is greater than the first threshold and the velocity of the vehicle is greater than the second threshold;

an active rear steering compensation module system comprising a feature state module, wherein the feature state module is configured to control the state of the active rear steering system; and

a computing system, comprising:

data processing hardware; and

memory hardware in communication with the data processing hardware, the memory hardware storing instructions that, when executed on the data processing hardware, cause the data processing hardware to perform operations comprising:

determining a desired effective steering angle based on a desired path of the vehicle;

measuring a front road wheel angle and the rear road wheel angle;

determining an actual effective steering angle;

determining an effective steering angle error based on the desired effective steering angle and the actual effective steering angle;

generating a torque command for an electronic power steering system based on the effective steering angle error; and

controlling an active rear steering system independently from the electronic power steering system.

13 . The vehicle management system of claim 12 , wherein determining the actual effective steering angle further comprises evaluating a difference between the front road wheel angle and the rear road wheel angle.

14 . The vehicle management system of claim 13 , wherein determining the effective steering angle error further comprises determining a difference between the desired effective steering angle and the actual effective steering angle.

15 . The method of claim 1 , wherein estimating the high resolution rear road wheel angle includes evaluating the low resolution rear road wheel angle using a detection module that triggers a ratio estimator module when the low resolution rear road wheel angle has at least one of a rising edge, a positive value, a falling edge, and a negative value.

16 . The method of claim 1 , wherein the predictive ratio is an instantaneous ratio that accounts for the low resolution rear road wheel angle and the hand wheel angle, and wherein the high resolution rear road wheel angle is estimated by taking a product of the predictive ratio and the hand wheel angle.

17 . The method of claim 1 , further comprising reinitializing the predictive ratio using a look-up table if there is a significant change in vehicle speed.

18 . The vehicle management system of claim 12 , further comprising estimating a high resolution rear road wheel angle including evaluating a low resolution rear road wheel angle using a detection module that triggers a ratio estimator module when the low resolution rear road wheel angle has at least one of a rising edge, a positive value, a falling edge, and a negative value.

19 . The vehicle management system of claim 18 , wherein estimating a high resolution rear road wheel angle includes estimating the high resolution rear road wheel angle using a predictive ratio, the predictive ratio being an instantaneous ratio that accounts for a low resolution rear road wheel angle and a hand wheel angle, and wherein the high resolution rear road wheel angle is estimated by taking a product of the predictive ratio and the hand wheel angle.

20 . The vehicle management system of claim 19 , further comprising reinitializing the predictive ratio using a look-up table if there is a significant change in vehicle speed.