Force and Position Control of a Solenoid Injected Monopropellant Powered Actuator

This paper describes the control of a direct-injection, liquid monoproplellant powered actuation system, which was developed for the purpose of providing mechanical power to autonomous human-scale robots. The actuation system utilizes the catalytic decomposition of a monopropllant as a hot gas generator for powering a pneumatic actuator. Pressurization of the respective sides of a pneumatic actuator. is provided via solenoid injection valves, which control the flow of the monopropellant through a catalyst pack into the respective sides of the cylinder. Depressurization is provided by a three-way proportional spool valve, which proportionally exhausts one of the two cylinder chambers. This paper describes a controller that coordinates the control of the two discrete injection valves, together with the control of the proportional exhaust valve, in order to provide actuator force tracking. The controller is implemented on a prototype system with a closed-loop servo controller. Experimental results indicate effective position and force tracking.Copyright © 2004 by ASME