Research was completed to investigate the use of high-speed on\off valves in the control of a hydraulic actuator. This work was completed as part of efforts to improve the accuracy and smoothness of travel for a six-degree-of-freedom testing machine. A mathematical representation of the system was developed that correctly predicted experimental results when a single command pulse was sent to the valves. For experiments involving a series of pulses to the valves the simulated and experimental results generally agreed at lower duty cycles, however, at higher duty cycles there was some separation in the results due to assumptions made in the simulation.

Keywords: on/off valves, digital hydraulics, position control, simulation and modelling