Design optimization and redundant actuation selection for an efficient assistive robotic exoskeleton

Selection of an actuation system for assistive robotic exoskeletons requires careful consideration of various design factors. It is generally the requirement of the system to produce lightweight and power-efficient systems. In some cases, the torque and power requirements could be relaxed by using redundant systems. This paper involves the study of one such case in which the actuation redundancy of the system will be exploited, and the design optimization will be explored for a rigid and an elastic system. A multi-factor optimization technique will be developed for a redundant elastic actuation system. An actuator design framework will be used to evaluate the different actuator choices to determine the best motor and transmission system combination in a redundant actuation system arrangement. This will be evaluated for a rigid, parallel, and series elastic actuation system. The optimal redundant actuation system significantly reduced the power requirements of the system. The case study was virtually implemented. It was established that variable parallel elastic actuators (V-PEA) performed better as compared to variable series elastic actuators (V-SEA).