The Reciprocating Chemical Muscle (RCM) is a mechanism that takes advantage of the superior energy density of chemical reactions. It is a regenerative device that converts chemical energy into motion through a direct noncombustive chemical reaction.
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Function
RCM is capable of generating autonomic wing beating from a chemical energy source. It can also be used to provide a small amount of electricity to the onboard control systems. It further helps in differential lift enhancement on the wings to achieve roll and, hence, steered flight. A large test bed for RCM technique is in the manufacturing of insect-like MAVs. The first generation of RCM was large and had a reciprocating frequency of approximately 10 Hz. The later generations developed were very small and lighter. Also the reciprocating frequency of this generation RCM was as high as 60 Hz. The Reciprocating Chemical Muscle was invented by Prof. Robert C. Michelson of the Georgia Tech Research Institute and implemented up through its fourth generation by Nino Amarena of ETS Laboratories.
Benefits
Particular benefits of the RCM are that it:
- requires no ignition source (thereby allowing it to work in explosive atmospheres),
- is anaerobic (thereby allowing it to operate underwater or in oxygen-free environments such as the lower atmosphere of the planet Mars),
- thermoelectrically generates electrical energy from its own exothermic metabolism, and
- converts chemically-bound potential energy directly into kinetic energy with greater energy density than batteries.
Specific Uses
The Reciprocating Chemical Muscle was developed as a drive mechanism for the flapping wings of the Entomopter. The RCM reuses energy many times before releasing it into its surroundings. First of all, it converts mainly heat energy into flapping wing motion in the Entomopter. Then heat is scavenged for thermoelectric generation in support of ancillary systems. Waste gas from the chemical decomposition of the fuel is then used to create an FMCW (frequency modulated continuous wave) acoustic ranging signal that is Doppler insensitive (used for obstacle avoidance). Waste gas is then passed through an ejector to entrain external atmospheric gases in order to increase mass flow and decrease waste gas temperature so that lower temperature components can be used down stream. Some waste gas is diverted into gas bearings for rotational and linear moving components. Finally remaining waste gas is vectored into the wings where it is used for circulation-controlled lift augmentation (Coanda Effect). Any remaining gas can be used for vectored thrust, however if the gas budgets are correctly designed, there should be no extra gas beyond the circulation control points. The features of the RCM are tailored to the Entomopter in order to conserve energy.
References
http://avdil.gtri.gatech.edu/RCM/RCM/Entomopter/EntomopterProject.html
See: “Reciprocating Chemical Muscle (RCM) and Method for Using Same”, U.S. Patent No. 6,446,909, September 10, 2002
