Theoretical Model Construction of Deformation-Force for Soft Grippers Part II: Displacement Control Based Intrinsic Force Sensing

TL;DR

This paper introduces a displacement-force mathematical model for soft grippers that enables precise contact force estimation from deformation measurements without sensors, improving force control in compliant robotic grasping.

Contribution

It develops a novel displacement-force model for compliant grippers, allowing intrinsic force sensing solely based on shape deformation, advancing force-aware grasping capabilities.

Findings

Accurately estimates contact force with about 3-4% error

Validates model through simulations compared to FEA

Works effectively across various design parameters

Abstract

Force-aware grasping is an essential capability for most robots in practical applications. Especially for compliant grippers, such as Fin-Ray grippers, it still remains challenging to build a bidirectional mathematical model that mutually maps the shape deformation and contact force. Part I of this article has constructed the force-displacement relationship for design optimization through the co-rotational theory. In Part II, we further devise a displacement-force mathematical model, enabling the compliant gripper to precisely estimate contact force from deformations sensor-free. The presented displacement-force model elaborately investigates contact forces and provides force feedback for a force control system of a gripper, where deformation appears as displacements in contact points. Afterward, simulation experiments are conducted to evaluate the performance of the proposed model through comparisons with the finite-element analysis (FEA) in Ansys. Simulation results reveal that the proposed model accurately estimates contact force, with an average error of around 3% and 4% for single or multiple node cases, respectively, regardless of various design parameters (Part I of this article is released in Arxiv1)