Robust Mu-Controller for Electro-Hydraulic Steering System

The paper presents the design of robust mu-controller for a laboratory test-bench composed of electrohydraulic-steering unit (EHSU), steering cylinder, 32-bit microcontroller, steering wheel and joystick. The controller design is based on an identified multivariable linear state-space model of the test-bench. Uncertain elements are introduced in the model from identification to account for unmodelled dynamic effects due to nonlinearities. Then the system is represented in a robust control framework and the structured singular value of the closed loop system is minimized with a DK iterative procedure to obtain robust stability and performance.