抄録
Ever since fast-switching solenoid valves were accepted as a powerful device for interfacing hydraulic systems with electronics, mechatronics technology for hydraulic actuators has developed rapidly. Such actuator development, however, has been mainly concentrated on linear motion actuators, as a result, the development of rotary-type actuators has still yet to reach a sufficient level.
A rotary-type actuator acts as an actuator by converting hydraulic energy to mechanical rotational motion within a specified angle, having a wide necessary applications. This study deals with a vane-type rotary actuator since it is superior as regards its high torque/inertia ratio and small size. By constructing a systemin which the actuator is operated by two 3-way solenoid valves, a differential-pulse width modulation method has been adopted as the method for digital control for the system. The solenoid valves in this system act as converters of the electronic-pulse signals to hydraulic ones. An arbitrary pulse width of the pressure difference across both sides of the actuator is obtained by adjusting the switching time of each valve.
The dynamic characteristics of the system were investigated by way of experiments and digital simulations. Thus it was clarified that the actuator, operated by differential-PWM, shows good linearity as a control element, achieving accurate positioning. Consequently, the availability of the system is well confirmed. Furthermore, it was recognized that the mathematical model used in this simulation might serve as a comparatively simplified model for describing the dynamics of this system.
