Design, Calibration, and Control of Compliant Force-sensing Gripping Pads for Humanoid Robots

This paper introduces a low-cost and light weight design for compliant gripping pads to be used for manipulating box-like objects with smaller sized humanoid robots. These pads measure gripping forces and center of pressure. A calibration algorithm is presented for these pads. A hybrid force-alignment-position control system is proposed to regulate the gripping forces and to ensure the surface alignment between the grippers and the object. Limit surface theory is incorporated as a contact friction modeling approach to determine the gripping forces for slippage avoidance. The integrated hardware and software system is demonstrated with a NAO humanoid robot. The pad design and associated software is open sourced. Experiments show the effectiveness of the overall approach.