Monopropellant Driven Free Piston Hydraulic Pump (FPHP)

Tim McGee and Justin Raade

The lack of compact, efficient, and lightweight power sources impedes the realization of mobile robotic devices that operate autonomously for periods of hours.  During the last year, The Human Engineering Laboratory has developed a novel free piston hydraulic pump to supply power for mobile robotic systems.  This power source is capable of operation in environments with no oxygen, such as underwater and space, with an energy density exceeding that of electric batteries.  The basic design incorporates several innovative features.  High concentration monopropellant (e.g. hydrogen peroxide) decomposes into steam and oxygen when exposed to a solid catalyst bed such as silver or platinum.  The energy released by this reaction can be harnessed in the novel engine/pump, producing high-pressure hydraulic flow to power actuators.  Since the reaction does not require an oxidizer, fuel/oxidizer mixing is eliminated.  This allows the design of simple, lightweight systems with increased power and energy density, and operation in oxygen free environments.  The design, unlike the internal combustion engine, produces power on demand, eliminating idling when there is no load on the system.  Steam and oxygen are the only byproducts of this power supply, and for many applications it will have no traceable signature.

Click for Animation of FPHP Operation