A variable rest length impedance grasping strategy in the port-Hamiltonian framework

TL;DR

This paper introduces a novel impedance grasping strategy within the port-Hamiltonian framework that employs a variable rest-length virtual spring to ensure smooth contact transitions and desired grasping forces.

Contribution

It presents a new impedance control method using a variable rest-length virtual spring in the port-Hamiltonian framework, enabling stable contact transitions and force regulation.

Findings

Successful simulation results demonstrating the approach.

Experimental validation confirming effectiveness.

Enhanced smoothness in contact transitions.

Abstract

This work is devoted to an impedance grasping strategy for a class of standard mechanical systems in the port-Hamiltonian framework. We embed a variable rest-length of the springs of the existing impedance grasping strategy in order to achieve a stable non-contact to contact transition, and a desired grasping force. We utilize the port-Hamiltonian structure of standard mechanical systems. First, we utilize a change of variables that transforms the port-Hamiltonian system into one with a constant mass-inertia matrix. We then achieve impedance grasping control via a \emph{virtual spring} with a variable rest-length. The force that is exerted by the virtual spring leads to a dissipation term in the impedance grasping controller, which is needed to obtain a smoother non-contact to contact transition. Simulations and experimental results are given in order to motivate our results.