Robust sliding mode control of hydraulic valves

Describes a robust sliding mode (SLM) controller for proportional solenoid valves. Such valves are common in industry due to their simple construction and low cost. The valve used in this study consists of a flow metering spool which is positioned by balancing the force from a solenoid against that of a return spring. The open loop dynamics of these valves are highly nonlinear; the inductance of the solenoid (and the generated force) varies with displacement, and the spool is subject to large hydraulic flow reaction forces