Linearizing compensation by PWM driving and feedback control of fishing line artificial muscle

Abstract

Soft actuators are attracting attention as safe driving sources suitable for robots coexisting in human living environment. As one of the promising actuators, a fishing line artificial muscle has been proposed. It is manufactured by twisting nylon fiber into coil shape. It expands and contracts in response to temperature change. By using conductive nylon fiber as a material or winding a nichrome wire, it is possible to drive electrically by Joule heating. The actuator is able to control by simple driving circuit and feedback control method; however, a squared nonlinearity due to Joule's law exists in response characteristics. In this research, we apply a linearizing compensation by PWM drive and simple feedback control with unti-windup method. The proposed method is investigated through experiments.