ABSTRACT
In mechatronic engineering, there exist three common actuators used in automation system, that is, servo motor, electro-hydraulic, and pneumatic. Each method has its own advantages to address different control problems. Since some unknown parametric variation may be significant in different working conditions, many state/output feedback controllers cannot be well established to guarantee the dynamic performance of electro-hydraulic servo systems (EHS). The other difficulty in EHS is the undesirable dynamic behavior of the established controller due to the ignorance of the largely unknown disturbance caused by the dynamic external load. Recently, there have been several control methods applied in electro-hydraulic control system. The classical approach to the control of EHSs is proportional integral derivative (PID) control, which is easy to be used in industry. Variable control parameters of PID controllers are adopted to suit the variable characteristics of the dynamic model.
