Pulse Width Modulation of Water Jet Propulsion Systems Using High Speed Coanda Effect Valves

Abstract

An integrated highspeed valve switching and pump output control scheme are developed for precision maneuvering of underwater vehicles. Highspeed Coandaeffect valves combined with a centrifugal pump allow for precise control of thrust force using a unique pulse width modulation (PWM) control scheme, where both pulse width and pulse height are controlled in a coordinated manner. Dead zones and other complex nonlinear dynamics of traditional propeller thrusters and water jet pumps are avoided with use of the integrated pumpvalve control. Three control algorithms for coordinating valve switching and pump output are presented. A simplified nonlinear hydrodynamic model of underwater vehicles is constructed, and design tradeoffs between PWM frequency and pulse height, with regard to steady state oscillations, are addressed. The control algorithms are implemented on a prototype underwater vehicle and the theoretical results are verified through experiments.