On the Describing Functions of PWM Pneumatic High-Speed On-Off Valves

High-speed on-off valves are widey used in PWM electropneumatic servo sys- tems and their characteristics are generally described by their on and off delay time. This paper focuses on establishing the relationships between their on-off switching behaviors and their frequency response characteristics. A method is proposed by which the frequency response characteristics of an analog PWM high-speed on-off valve can be calculated for inputs whose periods are certain multiples of the carrier period, based on its switching be- haviors. Thus, a simple and direct describing function for a PWM high-speed on-off valve is established.