Development of Hydraulic Load Simulator for Force Control with High Precision

Nowadays, hydraulic actuators play an important role in a modern industry where controlled force or position with high accuracy is the most significant demand. This paper presents a new kind of hydraulic load simulator (HLS) for conducting performance and stability test in the bench system where force control is important. The system model consists of a hybrid hydro-electric actuator and another hydraulic circuit generating disturbances. For the purpose of improving force control performance of hybrid systems, a robust force controller using Quantitative Feedback Theory (QFT) technique applied to the HLS is also proposed in this paper. The controller is designed to satisfy the robust performance requirement, tracking performance specification, and disturbance attenuation despite uncertainties of HLS. Experiments are carried out to evaluate the effectiveness of the proposed control method applied for hydraulic systems even in the large varying perturbation.