An Experimental Study of Model-based Control for Planar Handed Shearing Auxetics Robots

TL;DR

This paper develops a model-based control strategy for planar Handed Shearing Auxetics robots, enabling precise task-space regulation despite complex, coupled elastic and gravitational effects, validated through experiments.

Contribution

It introduces a collocated form of the equations of motion and a P-satI-D controller with force compensation for controlling HSA robots.

Findings

Successful experimental verification of the control strategy

Effective regulation of robot motion in task space

Handling of complex elastic and gravitational forces

Abstract

Parallel robots based on Handed Shearing Auxetics (HSAs) can implement complex motions using standard electric motors while maintaining the complete softness of the structure, thanks to specifically designed architected metamaterials. However, their control is especially challenging due to varying and coupled stiffness, shearing, non-affine terms in the actuation model, and underactuation. In this paper, we present a model-based control strategy for planar HSA robots enabling regulation in task space. We formulate equations of motion, show that they admit a collocated form, and design a P-satI-D feedback controller with compensation for elastic and gravitational forces. We experimentally identify and verify the proposed control strategy in closed loop.