Synthesis of a 2DOF Linear Quadratic Gaussian Position Control for a Steer-by-Wire System in Highly Automated Driving Applications

The Steer-by-Wire (SbW) steering system is a key technology for highly automated driving. For automated lateral vehicle guidance, the precise position control of the SbW Front Axle Actuator is an essential prerequisite. This paper presents the modeling, control synthesis, control loop analysis, and vehicle performance evaluation of the position control for the SbW Front Axle Actuator. Based on a nonlinear model of the plant a simplified linear system model is derived. This model yields the basis for the design of a Two-Degrees of Freedom Linear Quadratic Gaussian Control (2DOF LQG control), which allows an independent design of the command and the disturbance response. Besides a linear analysis of the control performance and stability, real vehicle tests for different driving maneuvers are conducted to verify simulation results and get a representative picture of the control performance.