State observers for output feedback control of electro-hydraulic systems

Electro-hydraulic systems are the updated version of conventional valve-controlled hydraulics. This actuation technology, which is crucial in many fields of industry, still has room for improvement in some areas. In this regard, feedback control is challenging as only the hydraulic actuator's position and pressure drop are typically measured for practical reasons. Thus, our focus is on constructing a state observer because knowing all the system’s state variables, including the actuator velocity, is desirable for achieving effective closed-loop position control. We propose a feedback linearization approach for output feedback control by developing an observer relying only on the measured position and pressures. We leverage linear matrix inequalities (LMIs) to obtain a proper observer gain. This unconventional approach for electro-hydraulic drives leads to satisfactory observer behavior. Therefore, this contribution further establishes electro-hydraulic systems by proposing novel alternatives to facilitate their control.