Metal hydride fluidic artificial muscle actuation system

The study presented here introduces a new actuation system that couples a fluidic artificial muscle designed by Festo, with a metal hydride hydrogen compressor to create a compact, lightweight system capable of high forces, completely noiseless and producing smooth actuation. The metal hydride hydrogen compressor replaces the pneumatic systems presently used to power fluidic artificial muscles, and the system can potentially be developed further for space applications and for use in extreme environments.;A model for the complete system is developed by coupling (a) a model of the actuator behavior based on a previous method used for pneumatic artificial muscles, and (b) a model of the metal hydride reactor based on a simple one-dimensional, numerical thermal analysis using a finite time approach to the thermodynamics. The analysis is restricted in some aspects concerning the complexity of the hydriding/dehydriding chemical process of the system and the three-dimensional geometry of the reactor, but it provides a useful comparison to other actuation devices and clearly reveals the parameters necessary for optimization of the actuation system in future work.;When compared to the other previously developed metal hydride actuation systems, the potential for increasing the reaction kinetics and improving the overall power output of the system is revealed; otherwise the system shows comparable work output and has the benefits of biological muscle like properties [1] for use in robotic systems, and smooth actuation, which can be temperamental/lacking using the metal bellows actuator of the other system.;A comparison of the system to a range of common actuation devices, including a biological muscle, shows similar stress and strain relations, but minimal power and frequency due to the slow actuation time. Improving the reaction kinetics of the system should be the first approach to enhancing the system, along with optimization of the mass of metal hydride used in the reactor to produce a full actuation stoke of the fluidic muscle while minimizing system weight.