Artificial exomuscle investigations for applications—metal hydride

Abstract

In pursuing the development of bionic devices, Victhom identified a need for technologies that could replace current motorized systems and be better integrated into the human body motion. The actuators used to obtain large displacements are noisy, heavy, and do not adequately reproduce human muscle behavior. Subsequently, a project at Victhom was devoted to the development of active materials to obtain an artificial exomuscle actuator. An exhaustive literature review was done at Victhom to identify promising active materials for the development of artificial muscles. According to this review, metal hydrides were identified as a promising technology for artificial muscle development. Victhom's investigations focused on determining metal hydride actuator potential in the context of bionics technology. Based on metal hydride properties and artificial muscle requirements such as force, displacement and rise time, an exomuscle was built. In addition, a finite element model, including heat and mass transfer in the metal hydride, was developed and implemented in FEMLAB software.

Experimental study of a metal hydride driven braided artificial pneumatic muscle

“…The actuation system of this study couples a braided artificial pneumatic muscle (BAPM) that is driven by pressure input and a metal hydride compressor designed to reversibly absorb and desorb hydrogen gas (figure 1). The actuator and metal hydride reactor create a closed system that operates by heating the reactor containing the activated metal hydride resulting in the desorption of hydrogen gas which pressurizes the artificial muscle causing it to contract; the reactor is then cooled and the hydrogen gas is reabsorbed by the metal hydride causing the artificial muscle to relax [9][10][11][12]22]. The fluidic artificial muscle used in the system was developed by Festo [13] and is an enhanced design over the common braided artificial pneumatic muscle (BAPM) [14][15][16][17][18][19][20][21].…”

“…The isentropic work is based on the thermodynamics of a pneumatic artificial muscle [9][10][11][12][14][15][16][17][18][19][20][21]. The system is considered an unsteady flow system, where the mass entering the system is equal to the change in mass of the system, and the mass exiting the system is zero.…”