Non-linear Control of a Hydraulic Piston Actuator without Velocity Information

The mathematical models of hydraulic actuators are known to be non-linear. Therefore, in order to increase the dynamic performance of the closed-loop system, we have to take into account the significant non-linearities of the hydraulic plant in the controller design. In this contribution, we deal with so-called valve-controlled translational piston actuators. In general, they have the pleasing property to be exact input-to-state linearizable in the sense of the differential geometric control synthesis approach. However, in practical applications it often turns out that those controllers, which have to rely on the knowledge of the piston velocity, have problems in the case of noisy measurements. This is why, we propose an approach where the non-linear controller is designed in such a way that the control law is independent of the piston velocity. It can be even proven that the closed-loop system is globally asymptotically stable.