Magnetically Actuated Artificial Muscles for Applications in Battery-Powered Robots

Abstract

Artificial muscles are a class of actuator that is of particular interest to the field of soft robotics. Soft robots are characteristically pliable and are therefore well-suited to manipulating potentially fragile objects, such as fruits or even human users, and artificial muscles are the actuators that power soft robots. Many current artificial muscles, however, struggle with efficiency and actuation speed, and thus are impractical for a variety of applications. In this paper, we present a novel type of muscle, inspired by HASEL muscles invented by the Keplinger Research Group at the University of Colorado Boulder [3] [1], that uses magnetic force to rapidly expand or contract upon application of an electric current. HASEL muscles use electrostatic forces and are able to achieve both high efficiency and high actuation speed. How-ever, they operate at very high voltages ( 10 kV) and low current, which makes them difficult to use in self-contained robots, which are typically battery-operated and may have components packed close together [3]. This paper describes a novel muscle that, by relying on magnetic instead of electrostatic forces, operates at low voltage and high current to achieve a similar motion. Multiple designs of the new muscle were prototyped and tested, and although all had practical issues preventing them from working as intended, this paper details the issues encountered and the reasons behind them, develops a mathematical model of the muscle’s theoretical performance, and describes how future work might overcome the problems encountered.