Vehicle-trailer backing-up control system with vehicle rear wheel steering

A method of assisting a vehicle operator in backing an automotive vehicle and trailer combination in an operator-determined direction, said combination having a connection between a hitch on the rear of the vehicle and a tongue of the trailer and a hitch angle between the axis of the tongue and the longitudinal axis of the vehicle;

• said vehicle comprising operator-controlled front wheel steering, and rear wheel steering actuated by a computer having continual access to data comprising vehicle speed, front wheel angle, rear wheel angle and said hitch angle, said wheel angles being measured from said longitudinal axis;
• said method being conducted by said computer upon actuation by said operator with the vehicle and trailer then aligned with a first hitch angle, said method comprising
• (a) determining whether said first hitch angle is of a magnitude that requires the vehicle to be pulled ahead to reduce said angle and, if so determined, instructing the operator to drive the vehicle forward to reduce said angle;
• (b) requesting the operator to turn the front wheels to a front wheel angle for initiating backing of the vehicle in a direction desired by the operator for moving the trailer;
• (c) using said front wheel angle to determine a target hitch angle responsive to said front wheel angle;
• (d) determining whether counter steering of the front wheels is required to achieve said target hitch angle during vehicle-trailer backing and, if so determined, instructing the operator to temporarily counter steer the front wheels while continuing to back the vehicle;
• and thereafter
• (e) continually using current vehicle speed, front and rear wheel angles and hitch angle to determining the difference between the current hitch angle and the target hitch angle and continually determining a rear wheel steering angle to achieve said target hitch angle.