A Study on a New Energy Saving Load Simulator using Hybrid Actuator and QFT Technique

The use of hydraulic systems in industrial applications has become widespread due to their efficiency advantages. In recent years, hybrid actuation system, which combines electric and hydraulic technology in a compact unit, can be adapted to a wide variety of force, speed and torque requirements. Moreover, the hybrid actuation system has dealt with the energy consumption and noise problem existed in the conventional hydraulic system. The new low cost hybrid actuator using DC motor as a power supply unit is considered as a novel linear actuator with various applications. However, this efficiency gain is often accompanied by a degradation of system stability and control problems. In this paper, to maintain robust performance requirement, tracking performance specification, and disturbance attenuation requirement, the design of a robust force controller for the new hybrid actuator using quantitative feedback theory (QFT) is presented. A family of plants model is obtained from experimental frequency responses of the system in the presence of significant uncertainty. Experimental results show that highly robust force tracking by hybrid actuator could be achieved even if the stiffness of environment and set-point force change. In addition, it is understood that the new system has energy saving effect even though it has almost the same response as that of valve controlled system