SAE International High Performance Electromechanical Actuator for Active Rear Axle Kinematics of a Sports Car 2012-01-0974

An electromechanical actuator is presented for the active control of a sports car's rear axle kinematics with a high performance-to-size ratio not available on the market up to now. Toe and camber values of both rear wheels are controlled independently to reach the optimum position of the tire contact patch on the ground for each driving situation. The complete system utilizes 4 actuators and is known as Active Kinematics Suspension (AKS). The actuators substitute the camber and toe links in a multilink suspension, without major modifications, on the prototype of an existing car. The actuators are capable of covering the high axial forces seen in the links and can rapidly alter the wheel position. The heart of the actuator is a hollow-shaft brushless DC motor running efficiently in field control. It drives a recirculating ball-screw which transfers the motor's rotational motion to a translational displacement of a central rod. Packaging and manufacturing checks are performed in a 3D CAD environment using kinematic and tolerance analysis tools. Sizing of the detail parts are analyzed with the help of non-linear FEM methods to ensure geometric stability and high durability of the complete system. A first set of four actuators are tested on a 6-DOF bench, incorporating a full rear axle suspension system before installation in the prototype vehicle and final road tests.