Unified Kinematic and Dynamical Modeling of a Soft Robotic Arm by a Piecewise Universal Joint Model

TL;DR

This paper introduces a novel 3D kinematic and dynamic model for soft robotic arms that accounts for external forces and gravity, outperforming traditional PCC models in accuracy through experiments and simulations.

Contribution

It develops a piecewise universal joint model for soft robots, improving modeling accuracy under external forces and gravity compared to existing PCC-based models.

Findings

Maximum position error reduced by 6.7 times

Maximum rotation error reduced by 4.6 times

Model validated through experiments and simulations

Abstract

The compliance of soft robotic arms renders the development of accurate kinematic & dynamical models especially challenging. The most widely used model in soft robotic kinematics assumes Piecewise Constant Curvature (PCC). However, PCC fails to effectively handle external forces, or even the influence of gravity, since the robot does not deform with a constant curvature under these conditions. In this paper, we establish three-dimensional (3D) modeling of a multi-segment soft robotic arm under the less restrictive assumption that each segment of the arm is deformed on a plane without twisting. We devise a kinematic and dynamical model for the soft arm by deriving equivalence to a serial universal joint robot. Numerous experiments on the real robot platform along with simulations attest to the modeling accuracy of our approach in 3D motion with load. The maximum position/rotation error of the proposed model is verified 6.7x/4.6x lower than the PCC model considering gravity and external forces.