A METHOD AND A SYSTEM FOR CONTROLLING VEHICLE LANE HOLDING

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.