Robust control design of an electro-hydraulic actuator

The paper proposes a hierarchical control design of an electro-hydraulic actuator. The high-level hydromotor is modeled with a linear form with parametric uncertainty, while the low-level spool valve is modeled with a polynomial system. The subsystems require different control strategies. At the high level a robust H_∞/μ control is used in order to meet the performance specifcations. At the low level a Control Lyapunov Function-based algorithm is proposed, which calculates discrete control input values for the valve. The interaction between the two control systems is guaranteed by the spool displacement, which is the control input at the high level and must be tracked at the low level. The operation of the actuator control system is illustrated through a simulation example.