Output feedback nonlinear energy-saving position control of electro-hydraulic asymmetric actuator

Both precise tracking performance and significant energy-saving effect are important issues for electro-hydraulic systems. Different from other available actuation methods, the electro-hydraulic systems generally suffer from severe energy consumption. To deal with the problem of energy saving and position tracking simultaneously, an output feedback nonlinear energy-saving controller is presented for electro-hydraulic asymmetric actuator. Specifically, the pump pressure is variable controlled in an open-loop manner based on the desired trajectory and system parameters to improve the system efficiency according to the concept of load-sensing control. Additionally, both the system states and the lumped uncertainties including parametric uncertainties and uncertain nonlinearities are estimated by an extended sliding mode observer. Moreover, a robust tracking controller is constructed to ensure a prescribed tracking performance. Thus, the multi-problem is resolved using only position measurement. The stability of the controller is verified by Lyapunov method, and the internal dynamics are demonstrated. The effectiveness of the controller is demonstrated by comparative experimental results.