Speed Control and Position Estimation of Small Hydraulic Cylinders for Digital Clay Using PWM Method

Digital Clay is a novel 3D computer input and output device for surface shape and haptic effects. The device consists of arrays of fluidically actuated cells under the control of valves connected to two pressure reservoirs in a manner ultimately suitable to an implementation in MEMS technology. At the current stage, it is very difficult to implement a tiny position sensor into each tiny cell. This paper presents a method of speed control and position estimation for the cells of digital clay using only low cost pressure sensors without any position-sensing device.