Development and Control of Evasive Steer Assist Using Rear Wheel Steering

A first step towards autonomous rear-end collision avoidance is to start providing natural support to driver in avoiding collision by steering and braking intervention. The proposed system detects slower-moving and stationary vehicles ahead and classifies the risk of having a rear-end-collision. If the risk is high and there is insufficient space to avoid a collision by braking only, the system helps the driver to steer around the obstacle by steering rear toe angle of the wheels individually. A lot of research already exist in the rear wheel steering but the role of rear wheel steering in collision avoidance is not researched yet in great details. Rear wheel steering is used to increase agility and manoeuvrability of vehicle at lower vehicle speed and stability of vehicle at higher vehicle speed. In the situation of the high speed rear end collision where steering is more effective than braking the strategy of control design of rear wheel steering needs to be dynamically updated. Linear threat assessment and path planning followed by optimal control of the trajectory in combination with driver steering shows a significant improvement in collision avoidance by steering. A test vehicle Mondeo is equipped with rear wheel steering is tested at different vehicle speed for collision avoidance against stationary and moving obstacles. A set of metrics are created to show the performance improvement against the base design of the vehicle.