A method and a system for controlling vehicle lane holding

Abstract

The present invention relates to a method for controlling vehicle lane holding for a vehicle with an electric power assisted steering by means of a steering system ( 100 ) with a steering assistance actuator and one or more controllable vehicle state actuators comprising measurement of at least one vehicle position input signal with using an on-board vision system for determination of a relative vehicle lane position in the form of a lane curvature, transformation of the relative vehicle lane position to a target yaw and/or lateral vehicle state, measuring at least one steering input signal, determination from said one or more measured steering input signals a torque value applied by the driver via a steering wheel ( 120 ), transformation of said torque value to a relative to the afore-mentioned target yaw and/or lateral vehicle state a driver target relative yaw and/or lateral vehicle state, adding said target yaw and/or lateral vehicle state and said driver target relative yaw and/or lateral vehicle state together, and using the resulting yaw and/or lateral vehicle state as a reference signal to one or more controllers for the mentioned control of the one or more vehicle state actuators.

1 . A method for controlling vehicle lane holding for a vehicle comprising an electric power assisted steering by means of a steering system with a steering assistance actuator and one or more controllable vehicle state actuators and comprising an on-board vision system, incorporating the steps of:
 measurement, with the aid of the on-board vision system, using one or more sensors of at least one vehicle position input signal representing one or more vehicle states,   determination, in a relative vehicle position calculation function or means, from said one or more measured vehicle position input signals of a relative vehicle lane position in the form of a lane curvature and/or a lane curvature derivative,   calculation, in the relative vehicle position calculation function or means, of a target lateral state vector consisting of one or more of the following target values; a target yaw and/or lateral vehicle state and a derivative of said target yaw and/or lateral vehicle state,   measurement of at least one steering input signal with the aid of a sensor,   determination in a driver torque calculation function or means, from said one or more measured steering input signals, of a torque value applied by the driver via a steering wheel, wherein   
       method further comprises the steps of:
 transformation, in a target relative vehicle state calculation means or function, of said torque value applied by the driver to a, relative to the afore-mentioned target lateral state vector, target delta lateral state vector, consisting of one or more of the following target delta values; a target delta yaw and/or lateral vehicle state and a derivative of said target delta yaw and/or lateral vehicle state, 
 adding said target lateral state vector and said target delta lateral state vector together, 
 using a from the addition ( 460 ) resulting mixed control target lateral state vector as reference signal to one or more controllers for the control of the one or more vehicle state actuators. 
 
     
     
         2 . The method according to  claim 1 , wherein:
 the target lateral state vector at least comprises a target yaw and/or lateral vehicle state, and that said target yaw and/or lateral vehicle state is a target curvature, and in that   the target delta lateral state vector at least comprises a target delta yaw and/or lateral vehicle state, and that said target delta yaw and/or lateral vehicle state is a target delta curvature.   
     
     
         3 . The method according to  claim 2 , wherein:
 the target lateral state vector further comprises a derivative of the target yaw and/or lateral vehicle state, and that said derivative of the target yaw and/or lateral vehicle state is a target curvature derivative, and in that   the target delta lateral state vector further comprises a derivative of the target delta yaw and/or lateral vehicle state, and that said derivative of the target delta yaw and/or lateral vehicle state is a target delta curvature derivative.   
     
     
         4 . The method according to  claim 1 , wherein from the torque value applied by the driver via a steering wheel, a compensation torque comprising one or more of the following compensation torque parts:
 a tyre friction torque, which is a function of a sensed or estimated yaw and/or lateral vehicle state,   a steering system friction torque, which is a function of a sensed or estimated yaw and/or lateral vehicle state,   a damping torque, which is a function of a derivative of a sensed or estimated yaw and/or lateral vehicle state, and   a returnability torque, which is a function of a sensed or estimated yaw and/or lateral vehicle state,   
       is/are subtracted. 
     
     
         5 . The method according to  claim 4 , wherein the compensation torque at least comprises the tyre friction torque, and in that the sensed or estimated yaw and/or lateral vehicle state for the input to the tyre friction torque of the compensation torque part is a sensed or estimated steering angle. 
     
     
         6 . The method according to  claim 4 , wherein the compensation torque at least comprises the steering system friction torque, and in that the sensed or estimated yaw and/or lateral vehicle state for the input to the steering system friction torque of the compensation torque part is a sensed or estimated steering angle. 
     
     
         7 . The method according to  claim 1  wherein the compensation torque at least comprises the damping torque, and in that the derivative of the sensed or estimated yaw and/or lateral vehicle state for the input to the damping torque of the compensation torque part is a sensed or estimated steering angular speed. 
     
     
         8 . The method according to  claim 1 , wherein the compensation torque at least comprises the returnability torque, and in that the sensed or estimated yaw and/or lateral vehicle state for the input to the returnability torque of the compensation torque part is a sensed or estimated steering angle. 
     
     
         9 . The method according to  claim 1 , wherein the compensation torque at least comprises the tyre friction torque, and in that the tyre friction torque, which is a function of a sensed or estimated yaw and/or lateral vehicle state, is compensated by subtracting the target yaw and/or lateral vehicle state from the sensed or estimated yaw and/or lateral vehicle state to a new yaw and/or lateral vehicle state and then to use this new yaw and/or lateral vehicle state (instead of the sensed or estimated yaw and/or lateral vehicle state) as input to the tyre friction torque. 
     
     
         10 . The method according to  claim 1 , wherein the compensation torque at least comprises the steering system friction torque, and in that the steering system friction torque, which is a function of a sensed or estimated yaw and/or lateral vehicle state, is compensated by subtracting the target yaw and/or lateral vehicle state from the sensed or estimated yaw and/or lateral vehicle state to a new yaw and/or lateral vehicle state and then to use this new yaw and/or lateral vehicle state (instead of the sensed or estimated yaw and/or lateral vehicle state) as input to the steering system friction torque. 
     
     
         11 . The method according to  claim 1 , wherein the compensation torque at least comprises the damping torque, and in that the damping torque, which is a function of a derivative of a sensed or estimated yaw and/or lateral vehicle state, is compensated by subtracting the derivative of the target yaw and/or lateral vehicle state from the derivative of the sensed or estimated yaw and/or lateral vehicle state to a new derivative of a yaw and/or lateral vehicle state and then to use this new derivative of a yaw and/or lateral vehicle state (instead of the derivative of the sensed or estimated yaw and/or lateral vehicle state) as input to the damping torque. 
     
     
         12 . The method according to  claim 1 , wherein the compensation torque at least comprises the returnability torque, and in that the returnability torque, which is a function of a sensed or estimated yaw and/or lateral vehicle state, is compensated by subtracting the target yaw and/or lateral vehicle state from the sensed or estimated yaw and/or lateral vehicle state to a new yaw and/or lateral vehicle state and then to use this new yaw and/or lateral vehicle state (instead of the sensed or estimated yaw and/or lateral vehicle state) as input to the returnability torque. 
     
     
         13 . The method according to  claim 1  wherein the compensation torque at least comprises the tyre friction torque, and in that the tyre friction torque, which is a function of a sensed or estimated steering angle, is compensated by subtracting the target steering angle from the sensed or estimated steering angle to a new steering angle and then to use this new steering angle (instead of the sensed or estimated steering angle) as input to the tyre friction torque. 
     
     
         14 . The method according to  claim 1 , wherein the compensation torque at least comprises the steering system friction torque, and in that the steering system friction torque, which is a function of a sensed or estimated steering angle, is compensated by subtracting the target steering angle from the sensed or estimated steering angle to a new steering angle and then to use this new steering angle (instead of the sensed or estimated steering angle) as input to the steering system friction torque. 
     
     
         15 . The method according  claim 1 , wherein the compensation torque at least comprises the damping torque, and in that the damping torque, which is a function of a sensed or estimated steering angular speed, is compensated by subtracting the target steering angular speed from the sensed or estimated steering angular speed to a new steering angular speed and then to use this new steering angular speed (instead of the sensed or estimated steering angular speed) as input to the damping torque. 
     
     
         16 . The method according  claim 1 , wherein the compensation torque at least comprises the returnability torque, and in that the returnability torque, which is a function of a sensed or estimated steering angle, is compensated by subtracting the target steering angle from the sensed or estimated steering angle to a new steering angle and then to use this new steering angle (instead of the sensed or estimated steering angle) as input to the returnability torque. 
     
     
         17 . A system for controlling vehicle lane holding for a vehicle comprising an electric power assisted steering by means of a steering system with a steering assistance actuator and one or more controllable vehicle state actuators and comprising an on-board vision system, comprising:
 means for measurement, with the aid of the on-board vision system, using one or more sensors, of at least one vehicle position input signal representing one or more vehicle states,   a relative vehicle position calculation function or means adapted for determination, from said one or more measured vehicle position input signals, of a relative vehicle lane position in the form of a lane curvature and/or a lane curvature derivative, and for calculation, of a target lateral state vector consisting of one or more of the following target values; a target yaw and/or lateral vehicle state and a derivative of said target yaw and/or lateral vehicle state,   means for measurement of at least one steering input signal with the aid of a sensor,   driver torque calculation function or means for, from said one or more measured steering input signals, determination of a torque value applied by the driver via a steering wheel, wherein it further comprises:   a target relative vehicle state calculation means or function for transformation of said torque value applied by the driver to a, relative to the afore-mentioned target lateral state vector, target delta lateral state vector, consisting of one or more of the following target delta values; a target delta yaw and/or lateral vehicle state and a derivative of said target delta yaw and/or lateral vehicle state,   addition means for adding said target lateral state vector and said target delta lateral state vector together,   vehicle state control means using a from the addition resulting mixed control target lateral state vector as reference signal to one or more controllers for controlling the one or more vehicle state actuators.   
     
     
         18 . The system according to  claim 17 , wherein
 the target lateral state vector at least comprises a target yaw and/or lateral vehicle state, and that said target yaw and/or lateral vehicle state is a target curvature, and   the target delta lateral state vector at least comprises a target delta yaw and/or lateral vehicle state, and that said target delta yaw and/or lateral vehicle state is a target delta curvature.   
     
     
         19 . The system according to  claim 18 , wherein:
 the target lateral state vector further comprises a derivative of the target yaw and/or lateral vehicle state, and that said derivative of the target yaw and/or lateral vehicle state is a target curvature derivative, and in that   the target delta lateral state vector further comprises a derivative of the target delta yaw and/or lateral vehicle state, and that said derivative of the target delta yaw and/or lateral vehicle state is a target delta curvature derivative.