Unsteady flow rate generating system for gas using isothermal tank based on disturbance observer

A Generating system of unsteady flow rate for gas using an isothermal tank is proposed. With the servo valves installed at upstream and downstream of the isothermal tank, the unsteady flow can be completely controlled. Moreover, by analyzing the characteristics of the servo valve, a feed forward compensator is designed to improve the response of the system. A fuzzy-PID controller is introduced for the high nonlinearity of compressible fluids control system. Differential operation is involved in the control process, which may amplify the noise greatly. Hence a disturbance observer is employed to reduce the noise to a permissible range. The experiment shows that the frequency of the unsteady flow rate obtained from the generating system is up to 10 Hz.