Supernumerary Robotic Limbs for Next Generation Space Suit Technology

This paper discusses the incorporation of a pair of Supernumerary Robotic Limbs (SuperLimbs) onto the next generation of NASA space suits. The wearable robots attached to the space suit assist an astronaut in performing Extra-Vehicular Activities (EVAs). The SuperLimbs grab handrails fixed to the outside of a space vehicle to securely hold the astronaut body. The astronaut can use both hands for performing an EVA task, rather than using one hand for securing the body or operating a tether. The SuperLimbs can also assist an astronaut in repositioning the body and stabilizing it during an EVA mission. A control algorithm based on Admittance Control is developed for a) virtually reducing the inertial load of the entire body so that an astronaut can reposition his/her body with reduced effort, and b) bracing the body stably despite reaction forces and disturbances acting on the astronaut during an EVA operation. A full-scale prototype of Space Suit SuperLimbs was constructed and tested. Results from the experimentation indicated that with the aid of SuperLimbs, energy consumption during EVAs is reduced significantly.