Control of a Soft Robotic Arm Using a Piecewise Universal Joint Model

TL;DR

This paper introduces a novel control approach for soft robotic arms using a piecewise universal joint model, enabling improved trajectory tracking and end-effector positioning despite the arm's complex passive degrees of freedom.

Contribution

It develops and validates two closed-loop controllers based on a universal joint model, enhancing control accuracy and robustness for soft robotic arms.

Findings

Superior tracking accuracy with the configuration space controller

Reduced settling time and steady-state error with the task space controller

Effective control during interactions with the environment

Abstract

The 'infinite' passive degrees of freedom of soft robotic arms render their control especially challenging. In this paper, we leverage a previously developed model, which drawing equivalence of the soft arm to a series of universal joints, to design two closed-loop controllers: a configuration space controller for trajectory tracking and a task space controller for position control of the end effector. Extensive experiments and simulations on a four-segment soft arm attest to substantial improvement in terms of: a) superior tracking accuracy of the configuration space controller and b) reduced settling time and steady-state error of the task space controller. The task space controller is also verified to be effective in the presence of interactions between the soft arm and the environment.