Systematic method for selection of motor-reducer units to power a lower-body robotic exoskeleton

Abstract

ABSTRACT Powered exoskeletons are wearable robotic devices intended to provide extra power to ailing limbs during walking. The selection of appropriate motor and transmission is essential in enhancing the power-to-weight ratio of the system while keeping the cost down. This article presents a systematic method to size the motortransmission unit by taking into account the motor’s characteristics, transmission inertia, efficiency and cost of the system. Since a lower-limb exoskeleton system is designed for walking, clinical gait analysis data is used to assess the dynamic load requirements. An optimal selection of the motor and gearhead is made to power the hip joint of the exoskeleton. Choice of the motor-reducer unit is compared using different criteria such as maximizing load acceleration or peak power. The framework can be easily extended to other joints as well as to other types of exoskeletons.