Point-to-point trajectory tracking with two-degree-of-freedom robust control for a non-minimum phase electro-hydraulic system

Abstract

Electro-hydraulic actuator (EHA) system inherently suffers from uncertainties, nonlinearities and timevarying in its model parameters which makes the modeling and controller designs are more complicated. The main objective of this paper is to perform a robust control design using discretetime sliding mode control (DSMC) with two-degree-of-freedom (2-DOF) control strategy. The proposed controller consists of feedback and feedforward combination which capable to reduce phase lag and steady state error during the trajectory tracking of EHA system. The feedforward controller is developed by implementing the zero phase error tracking control (ZPETC) technique which the main difficulty arises from the nonminimum phase system with no stable inverse. A point-to-point trajectory is used in the experimental works to evaluate the performance of the DSMC. Experimental results reveal that the DMSC with 2-DOF control structure is highly robust and capable to deal with the uncertainties and disturbances occur during the position tracking control for different point of trajectories. It is also shows that the proposed controller can achieve better tracking performance as compared to conventional LQR and PID controller.

Robust Control for Non-Minimum Phase Systems with Actuator Faults: Application to Aircraft Longitudinal Flight Control

“…Generally, the linear quadratic regulator (LQR), which is based on the optimal control theory, offers more significant advantages than the classical control methods with respect to time response performance, control effort, robustness for uncertainty, and disturbance and noise rejection capabilities [20,21]. As reported in the literature, the LQR controller has been successfully applied to deal with various types of NMP dynamics, for instance, m-link robotic manipulators [22], phase electrohydraulic systems (EHS) [23], and wheeled bipedal robot with kinematic loops [24]. It is remarkable that the first significant application of multivariable control based on the linear quadratic regulator (LQR) started in the Boeing company (Chicago, IL, USA) in 1978 as a part of NASA's research programs [25].…”