Safe Grasping with a Force Controlled Soft Robotic Hand

TL;DR

This paper introduces a force-controlled soft robotic hand that uses sensor feedback and a PID controller to achieve safe, stable grasping of deformable objects, preventing damage and ensuring object stability.

Contribution

The work presents a novel soft robotic hand with integrated force sensing and a data-driven calibration method for force regulation, enabling safe grasping of deformable objects.

Findings

Successfully grasped deformable objects without damage

Achieved stable grasping through force regulation

Validated approach with experimental benchmarks

Abstract

Safe yet stable grasping requires a robotic hand to apply sufficient force on the object to immobilize it while keeping it from getting damaged. Soft robotic hands have been proposed for safe grasping due to their passive compliance, but even such a hand can crush objects if the applied force is too high. Thus for safe grasping, regulating the grasping force is of uttermost importance even with soft hands. In this work, we present a force controlled soft hand and use it to achieve safe grasping. To this end, resistive force and bend sensors are integrated in a soft hand, and a data-driven calibration method is proposed to estimate contact interaction forces. Given the force readings, the pneumatic pressures are regulated using a proportional-integral controller to achieve desired force. The controller is experimentally evaluated and benchmarked by grasping easily deformable objects such as plastic and paper cups without neither dropping nor deforming them. Together, the results demonstrate that our force controlled soft hand can grasp deformable objects in a safe yet stable manner.