Modeling and Motion Control of a Soft Robot

Abstract

A soft robot with locomotive abilities controlled by body deformations is modeled, analyzed, and then constructed in this study. The robot is composed of a thin steel shell, four sensors, and four shape memory alloy (SMA) springs. Due to the force exerted by the SMAs, the thin steel shell deforms and causes the robot to roll and move forward continuously. The study is conducted in four tiers. Initially, after producing a model of the soft robot, the constraint conditions of rolling actions from deformations are analyzed. Then, the relationship between the deformation and the heating time of SMAs is studied. A dynamic analysis on the rolling motion is presented based on the deformation of SMAs and the change in the robot's center of gravity. A dynamic simulation is also conducted to test the feasibility of the theory. The third tier consists of designing a closed-loop controller based on feedback data from the four deformable sensors, a feature that has never been applied to soft robots in previous studies. Finally, a prototype of the soft robot is built, and an experiment is conducted and compared to prove the validity of the theory.