Bionic Design to Reduce Driving Power for a Portable Elbow Exoskeleton Based on Gravity-balancing Coupled Model

Portability is an important performance to the design of exoskeleton for rehabilitation and assistance. However, the structure of traditional exoskeletons will decrease the portability because of their heavy weight and large volume. This paper proposes a novel bionic portable elbow exoskeleton based on a human-exoskeleton gravity-balancing coupled model. The variable stiffness characteristics of the coupled model is analyzed based on the static analysis. In addition, the optimization of human-exoskeleton joint points is analysis to improve the bionic motor characteristics of the exoskeleton. Theoretical prototype is designed and its driving power and dynamic performance are analyzed. Then, a prototype is designed and manufactured with a total weight of 375 g. The merits of driving power reducing is verified by simulation and the isokinetic experiments. The simulation and isokinetic results show that the driving torque and the driving power of the subject were significantly decreased with wearing the proposed exoskeleton. The driving torques are reduced 79.28% and 57.38% from the simulation results and isokinetic experiment results, respectively. The driving work of experiment was reduced by 56.5%. The development of the novel elbow exoskeleton with gravity-balancing mechanism can expand the application of exoskeleton in home-based rehabilitation.