Model Based Position Control of Soft Hydraulic Actuators

TL;DR

This paper presents a model-based control method for soft hydraulic actuators using energy shaping and a nonlinear observer, achieving high-precision positioning despite external disturbances.

Contribution

It introduces a novel control approach combining port-Hamiltonian modeling, energy shaping, and nonlinear observation for soft hydraulic actuators.

Findings

Achieves 0.043 mm positioning accuracy in experiments.

Effectively compensates for external forces up to 1 N.

Demonstrates robustness through simulations and experiments.

Abstract

In this article, we investigate the model based position control of soft hydraulic actuators arranged in an antagonistic pair. A dynamical model of the system is constructed by employing the port-Hamiltonian formulation. A control algorithm is designed with an energy shaping approach which accounts for the pressure dynamics of the fluid. A nonlinear observer is included to compensate the effect of unknown external forces. Simulations demonstrate the effectiveness of the proposed approach, and experiments achieve positioning accuracy of 0.043 mm with a standard deviation of 0.033 mm in the presence of constant external forces up to 1 N.