Monopropellant powered actuators for use in autonomous human-scaled robotics

Abstract

This paper presents a liquid-fuel powered pneumatic actuator appropriate for human-scale autonomous robotics. The motivation for this work is the development of a lightweight actuation system with system energy and power densities significantly greater than a DC motor and battery combination. For the scale of interest, the design tradeoffs between complexity of an energy conversion system and fuel specific energy density make many conventional approaches inappropriate. Conventional actuation, such as a battery powered DC motor system, does not possess adequate energy storage to perform significant amounts of mechanical work for significant periods of time autonomously. A system design comparison for a six-degree of freedom walking robot is presented which compares the expected performance of a monopropellant powered actuation system to a battery powered DC motor system. Results from this comparison demonstrate the viability of such an approach and indicate significant increases in energy and power densities. A single-degree of freedom manipulator was constructed to demonstrate this approach. Experimental results corroborate the expected energetic advantages.