Resonance Suppression of Electro-hydrostatic Actuator by Full State Feedback Controller Using Load-side Information and Relative Velocity

摘要

Hydraulic actuators have good power/weight ratio, and electro-hydrostatic actuators (EHAs), which is a way to control oil flow, are recently keeping attention. EHAs are directly driven by servomotors resulting in high power efficiency, low cost, and small systems. However, owing to inertia of servomotors, the control performance of EHAs has been believed to be lower than that of usual hydraulic systems, in which oil flow is controlled by servo valves. The target issue of this work is to improve the only one drawback of EHAs, control performance. In this research, we firstly show resonance generated by inertia of servomotors. Then, a full state feedback controller is proposed to suppress the resonance. Usually, a full state of resonant systems can be measured by two angular sensors, which measure angle responses of servomotors (motor-side) and hydraulic motors (load-side). However, there is oil leakage in hydraulic systems making full state feedback control unstable. To solve the problem, a new state equation using relative velocity between motor-sides and load-sides is proposed. The validity of the proposed method is experimentally verified.