2-Degrees of Freedom Linear Quadratic Gaussian Position Control (2DOF LQG Control) of the Front Axle Actuator of a Steer-by-Wire Steering System

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. Hereby high requirements regarding dynamics and stationary accuracy must be fulfilled, which require an active compensation of nonlinear friction and external disturbance forces. For the fulfillment of these requirements a Two-Degrees of Freedom Linear Quadratic Gaussian Position Control (2DOF LQG Control) was developed. This control allows an independent design of the command and disturbance response of the closed loop system by combining a dynamic feedforward control with an observer-based optimal state-space control. Thereby, the advantages of feedforward and feedback control are exploited. By considering all plant states for control an arbitrary design of the complete system dynamics is achieved. Real vehicle experiments confirm an excellent control performance of the approach.

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