Optimal Transmission Ratio Selection for Electric Motor Driven Actuators With Known Output Torque and Motion Trajectories

Abstract

This paper presents a method for selecting the optimal transmission ratio for an electric motor for applications for which the desired torque and motion at the transmission output are known a priori. Representative applications for which the desired output torque and motion are periodic and known include robotic manipulation, robotic locomotion, powered prostheses, and exoskeletons. Optimal transmission ratios are presented in two senses: one that minimizes the root-mean-square (RMS) electrical current and one that minimizes the RMS electrical power. An example application is presented in order to demonstrate the method for optimal transmission ratio selection.