Accurate Finite-Time Motion Control of Hydraulic Actuators With Event-Triggered Input

Generally, asymptotic tracking motion control algorithm can ensure the stability of the closed-loop system, but hardly exploits the potential system performance. As an alternative, a high-accuracy control method with finite-time regulation is studied in this paper for hydraulic actuators pertaining to complex unknowns and limited communication bandwidth. During system modeling, a hydraulic actuator system is expressed in the Brunovsky form with a lumped disturbance term, instead of the conventional semi-strict-feedback form, such that the tracking control can be transformed to the stabilizing problem. As a result, the homogeneity-based finite-time motion controller enables to be recursively constructed. This paper develops a finite-time observer to simultaneously estimate the partial unknown state and the lumped disturbance, with a short time, thereby improving the disturbance rejection and transient response. Moreover, a novel threshold triggering mechanism is proposed to alleviate the limited communication resources and ensure the relatively small amplitude fluctuation of control inputs via a minimum function. The stability and finite-time convergence of the closed-loop system are all proved. Meanwhile, the Zeno behavior is avoided. Finally, the proposed control scheme is tested and verified on the aero-engine Hardware-in-the-loop (HIL) test-rig with hydraulic actuators. Note to Practitioners— This paper displays how to utilize the event-triggered communication protocol and finite-time control for hydraulic actuators in the networked control systems. The designed event-triggered mechanism saves more communication resources while ensuring the satisfied motion control effect. Moreover, the internal and external uncertainties are all tackled with the developed finite-time observer. Experimental results verify that the proposed schemes are easily implemented, but with the plentiful performance improvements of motion control, disturbance attenuation (i.e., finite-time output tracking and unknown estimation), and the capability on saving network resources. In addition, the proposed event-driven control scheme is also feasible for other mechatronic systems, e.g., linear motor, DC motor and marine surface vehicles.