METHOD FOR DETERMINING CONTROLLED VARIABLE OF COORDINATE CONTROL ON SPLIT ROAD SURFACE USING DECELERATION OF VEHICLE
Disclosed herein is a method of determining a controlled variable of coordinate control on a split road surface using deceleration of a vehicle. The method includes calculating deceleration of the vehicle by differentiating a reference velocity (Vref) calculated by an electronic stability control system, calculating an override angle of an active front-wheel steering system by multiplying the deceleration of the vehicle by a control gain, determining a control direction of the vehicle, and obtaining a controlled variable for a steering angle by multiplying the calculated override angle of the active front-wheel steering system by the determined control direction of the vehicle. The method enables the vehicle to maintain a straight behavior without driver's steering intervention when the driver brakes on the split road surface
1 . A method of determining a controlled variable of coordinate control on a split road surface using deceleration of a vehicle, the method comprising:
calculating a deceleration of the vehicle by differentiating a reference velocity (Vref) calculated by an electronic stability control system;
calculating an override angle of an active front-wheel steering system by multiplying the deceleration of the vehicle by a control gain;
determining a control direction of the vehicle; and
obtaining a controlled variable for a steering angle by multiplying the calculated override angle of the active front-wheel steering system by the determined control direction of the vehicle.
2 . The method according to claim 1 , further comprising:
determining whether a driver intends to steer when braking on the road surface having dissymmetry friction;
applying a limit value of the controlled variable for the steering angle differently according to whether the driver intends to steer;
comparing the controlled variable for the steering angle with the limit value of the controlled variable for the steering angle;
outputting the controlled variable for the steering angle as a controlled variable if the controlled variable for the steering angle is less than or equal to the limit value of the controlled variable for the steering angle; and
outputting the limit value of the controlled variable for the steering angle as a controlled variable if the controlled variable for the steering angle is more than the limit value of the controlled variable for the steering angle.
3 . The method according to claim 1 wherein the control direction of the vehicle is set to 1 with respect to a “+” direction and −1 with respect to a “−” direction based on braking pressure of each of the left and right wheels.
4 . The method according to claim 2 wherein the determining whether a driver intends to steer is performed based on a driver's steering angle and a driver's steering angular velocity.