Terminal Sliding Mode Control of Electro-Hydrostatic Actuator Based on Disturbance Compensation

As a representative product of electro-hydraulic servo control technology, electro-hydrostatic actuator (EHA) has drawn the attention of numerous researchers and scholars, and has been extensively applied in engineering practice. However, existing research on EHA focuses on how to achieve better displacement control, and another important factor in the practical engineering application of EHA - the control of the piston rod actuating force - has not been given enough attention. Especially in the operating environment of electro-hydrostatic actuator, there are many complex non-linear factors, for instance, friction, the moment of inertia, variable loads, as well as internal and external disturbances under diverse operating conditions., which will affect the control effect of EHA actuating force, and it is difficult to achieve the ideal performance index with the traditional PID control method. To address this problem, this paper first designs a non-singular terminal sliding film controller (NTSM) for EHA actuation, and compensates the system disturbance in real time by expanding state observer (ESO), which avoids the jitter problem caused by high gain. Then, the stability and achievability of the non-singular terminal sliding mode control system are analyzed using Lyapunov theory. Finally, the results of the joint simulation experiments show that the control strategy can better suppress disturbances and has better robustness as well as higher control accuracy than the traditional PID.