Method and apparatus for preview-based vehicle lateral control

Abstract

A vehicle lateral control system that integrates both vehicle dynamics and kinematics control. The system includes a driver interpreter that provides desired vehicle dynamics and predicted vehicle path based on driver input. Error signals between the desired vehicle dynamics and measured vehicle dynamics, and between the predicted vehicle path and the measured vehicle target path are sent to dynamics and kinematics control processors for generating a separate dynamics and kinematics command signals, respectively, to minimize the errors. The command signals are integrated by a control integration processor to combine the commands to optimize the performance of stabilizing the vehicle and tracking the path. The integrated command signal can be used to control one or more of front wheel assist steering, rear-wheel assist steering or differential braking.

1 . A vehicle lateral control system for a vehicle, said system comprising: 
 a driver steering intent sensor for providing a driver steering intent signal;    a yaw rate sensor for providing a measured yaw rate signal of the yaw rate of the vehicle;    a lateral acceleration sensor for providing a measured lateral acceleration signal of the lateral acceleration of the vehicle;    a vehicle speed sensor for providing a measured speed signal of the speed of the vehicle;    a target path sub-system for providing a target path signal indicative of a path of the vehicle;    a command interpreter processor responsive to the driver steering intent signal and generating a desired yaw rate signal or a desired side-slip signal;    a first subtractor responsive to the desired yaw signal and the measured yaw rate signal or the desired side-slip signal and a side-slip estimation signal, said first subtractor generating a dynamical error signal;    a motion/path prediction processor responsive to the driver steering intent signal and generating a predicted path signal of the predicted path of the vehicle;    a second subtractor responsive to the predicted path signal and the target path signal, and generating a kinematical error signal;    a dynamics control processor responsive to the dynamical error signal and generating a dynamics control command signal;    a kinematics control processor responsive to the kinematical error signal and generating a kinematics control command signal; and    a control integration processor responsive to the dynamics control command signal and the kinematics control command signal, said control integration processor integrating the dynamics control command signal and the kinematics control command signal into an integrated control command signal.    
     
     
         2 . The system according to  claim 1  wherein the command interpreter processor employs a two-degree of freedom bicycle model using a high coefficient of friction road surface to generate the desired yaw rate signal or the desired side-slip, signal.  
     
     
         3 . The system according to  claim 1  wherein the motion/path prediction processor includes a vehicle dynamics estimation processor and a vehicle kinematics estimation processor, said vehicle dynamics estimation processor generating a vehicle state variable signal based on vehicle lateral velocity and vehicle yaw rate, and said vehicle kinematics estimation processor generating the predicted path signal based on the vehicle state variable signals.  
     
     
         4 . The system according to  claim 3  wherein the vehicle dynamics estimation processor employs a bicycle model and state feedback to generate the state variable signals.  
     
     
         5 . The system according to  claim 1  wherein the dynamics control processor employs a PID controller.  
     
     
         6 . The system according to  claim 1  wherein the kinematics control processor employs an optimal control process that minimizes a predefined cost function.  
     
     
         7 . The system according to  claim 1  wherein the driver steering intent sensor is a hand-wheel angle sensor.  
     
     
         8 . The system according to  claim 1  further comprising an actuator responsive to the integrated command signal from the control integration processor.  
     
     
         9 . The system according to  claim 8  wherein the actuator is selected from the group consisting of a front-wheel steering assist actuator, a rear-wheel steering assist actuator and/or a differential braking control actuator.  
     
     
         10 . The system according to  claim 1  wherein the target path sub-system is selected from the group consisting of a vision sub-system, a radar sub-system and a map sub-system with a GPS sensor.  
     
     
         11 . The system according to  claim 1  wherein the control integration processor transforms a slow data rate coordinate frame to a fast data rate coordinate frame.  
     
     
         12 . A vehicle control system comprising: 
 a vehicle dynamics control sub-system for generating a vehicle dynamics control command signal;    a vehicle kinematics control sub-system for generating a vehicle kinematics control command signal; and    a control integration sub-system responsive to the dynamics control command signal and the kinematics control command signal, said control integration sub-system combining the kinematics control command signal and the dynamics control command signal into an integrated control command signal.    
     
     
         13 . The system according to  claim 12  wherein the dynamics control sub-system is responsive to a plurality of sensor signals that measure vehicle dynamics.  
     
     
         14 . The system according to  claim 13  where the sensors include a yaw rate sensor, a lateral acceleration sensor and a vehicle speed sensor.  
     
     
         15 . The system according to  claim 12  wherein the dynamics control sub-system generates a dynamical error signal as the difference between measured vehicle dynamics and desired vehicle dynamics estimated from driver steering input.  
     
     
         16 . The system according to  claim 12  wherein the kinematics control sub-system includes a target path sub-system for providing a target path signal indicative of a path of the vehicle.  
     
     
         17 . The system according to  claim 16  wherein the target path sub-system includes one or more of a vision sub-system, a radar sub-system and a map sub-system with a GPS sensor.  
     
     
         18 . The system according to  claim 16  wherein the kinematics control sub-system generates an error signal as the difference between the target path signal and a predicted path from a driver steering input.  
     
     
         19 . A vehicle lateral control system for a vehicle, said system comprising: 
 a hand-wheel angle sensor for providing a driver steering intent signal;    a yaw rate sensor for providing a measured yaw rate signal of the yaw rate of the vehicle;    a lateral acceleration sensor for providing a measured lateral acceleration signal of the lateral acceleration of the vehicle;    a vehicle speed sensor for providing a measured speed signal of the speed of the vehicle;    a target path sub-system for providing a target path signal indicative of a path of the vehicle;    a command interpreter processor responsive to the driver steering intent signal and generating a desired yaw rate signal or desired side-slip signal;    a first subtractor responsive to the desired yaw rate signal and the measured yaw rate signal or the desired side-slip signal and a side-slip estimation signal, and generating a dynamical error signal;    a motion/path prediction processor responsive to the driver steering intent signal and generating a predicted path signal of the predicted path of the vehicle, said motion/path prediction processor including a vehicle dynamics estimation processor and a vehicle kinematics estimation processor, said vehicle estimation processor generating a vehicle state variable signal based on vehicle lateral velocity and vehicle yaw rate, and said vehicle kinematics estimation processor generating the predicted path signal based on the vehicle state variable signal;    a second subtractor responsive to the predicted path signal and the target path signal, and generating a kinematical error signal;    a dynamics control processor responsive to the dynamical error signal and generating a dynamics control command signal;    a kinematics control processor responsive to the kinematical error signal and generating a kinematics control command signal;    a control integration processor responsive to the dynamics control command signal and the kinematics control command signal, said control integration processor integrating in the dynamics control command signal and the kinematics control command signal into an integrated control command signal; and    an actuator responsive to the integrated command signal from the control integration processor for controlling the vehicle.    
     
     
         20 . The system according to  claim 19  wherein the command interpreter processor employs a two-degree of freedom bicycle model using a high coefficient of friction road surface to generate the desired yaw rate signal or the desired side-slip signal.  
     
     
         21 . The system according to  claim 19  wherein the kinematics control processor employs an optimal control process that minimizes a predefined cost function.  
     
     
         22 . The system according to  claim 19  wherein the actuator is selected from the group consisting of a front-wheel steering assist actuator, a rear-wheel steering assist actuator and a differential braking control actuator.  
     
     
         23 . The system according to  claim 19  wherein the target path sub-system is selected from the group consisting of a vision sub-system, a radar sub-system and a map sub-system with a GPS sensor.