Publications

Monopropellant Powered Systems

The motivation for this work is the development of a lightweight power supply and actuation system appropriate for untethered robotic platforms with system-level energy and power densities significantly greater than a DC motor and battery combination. Conventional actuation, such as a battery powered DC motor system, does not possess adequate energy density or power density to perform significant amounts of mechanical work for significant periods of time autonomously in a lightweight package. This monopropellant based approach utilizes the catalytic decomposition of hydrogen peroxide to produce hot pressurized gas for the controlled delivery of mechanical work utilizing pneumatic actuators.

In contrast to our work on the free-piston engine compressor, the monopropellant based work seeks a solution at the opposite end of the chemically powered devices spectrum: low convertor mass with a lower energy density fuel vs. higher convertor mass with a high energy density source. The monopropellant approach utilizes a simple and compact energy convertor (catalyst pack) but a lower energy density source (70% hydrogen peroxide with 0.4MJ/kg lower heating value). The free-piston engine compressor requires an intricate energy convertor (the engine) but utilizes a fuel with an energy density two orders of magnitude higher (propane with 46MJ/kg lower heating value). Both design philosophies seek a high system-specific work output – that is, a large amount of controlled work output per unit mass of the fuel/convertor/actuator system.

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