Design and energetic characterization of a liquid-propellant-powered actuator for selfpowered robots

Abstract—This paper describes the design of a power supply and actuation system appropriate for position or force controlled human-scale robots. The proposed approach utilizes a liquid monopropellant to generate hot gas, which is utilized to power a pneumatic-type actuation system. A prototype of the actuation system is described, and closed-loop tracking data are shown, which demonstrate good motion control. Experiments to char-acterize the energetic performance of a six-degree-of-freedom actuation system indicate that the proposed system with a diluted propellant offers an energetic figure of merit five times greater than battery-powered dc motors. Projections based on these experiments indicate that the same system powered by undiluted propellant would offer an energetic figure of merit an order of magnitude greater than a comparable battery-powered dc motor actuated system. Index Terms—Actuators, actuation, energy density, human-scale robot, hydrogen peroxide, monopropellant, pneu-matic, power supply, self-powered robot, service robot