Offset-free Model Predictive Control: A Ball Catching Application with a Spherical Soft Robotic Arm

TL;DR

This paper introduces an offset-free model predictive control method for a spherical soft robotic arm, significantly improving tracking accuracy and enabling a practical ball catching application by compensating for soft material dynamics.

Contribution

It develops an offset-free MPC that combines a linear model with disturbance estimation, addressing soft material effects for precise control.

Findings

35% reduction in tracking error compared to standard MPC

Successful demonstration of ball catching with the soft robotic arm

Enhanced control robustness for soft robotic systems

Abstract

This paper presents an offset-free model predictive controller for fast and accurate control of a spherical soft robotic arm. In this control scheme, a linear model is combined with an online disturbance estimation technique to systematically compensate model deviations. Dynamic effects such as material relaxation resulting from the use of soft materials can be addressed to achieve offset-free tracking. The tracking error can be reduced by 35% when compared to a standard model predictive controller without a disturbance compensation scheme. The improved tracking performance enables the realization of a ball catching application, where the spherical soft robotic arm can catch a ball thrown by a human.