Static Tactile Sensing for a Robotic Electronic Skin via an Electromechanical Impedance-Based Approach.

Cheng Liu,Fu-Kuo Chang,Lingling Lu,Yitao Zhuang,Amir Nasrollahi,Mohammad Faisal Haider

doi:10.3390/s20102830

Abstract

Tactile sensing is paramount for robots operating in human-centered environments to help in understanding interaction with objects. To enable robots to have sophisticated tactile sensing capability, researchers have developed different kinds of electronic skins for robotic hands and arms in order to realize the ‘sense of touch’. Recently, Stanford Structures and Composites Laboratory developed a robotic electronic skin based on a network of multi-modal micro-sensors. This skin was able to identify temperature profiles and detect arm strikes through embedded sensors. However, sensing for the static pressure load is yet to be investigated. In this work, an electromechanical impedance-based method is proposed to investigate the response of piezoelectric sensors under static normal pressure loads. The smart skin sample was firstly fabricated by embedding a piezoelectric sensor into the soft silicone. Then, a series of static pressure tests to the skin were conducted. Test results showed that the first peak of the real part impedance signal was sensitive to static pressure load, and by using the proposed diagnostic method, this test setup could detect a resolution of 0.5 N force. Numerical simulation methods were then performed to validate the experimental results. The results of the numerical simulation prove the validity of the experiments, as well as the robustness of the proposed method in detecting static pressure loads using the smart skin.

Highlights

Tactile sensing in human and animal skins enables them to touch, sense temperature, etc
The results of the numerical simulation prove the validity of the experiments, as well as the robustness of the proposed method in detecting static pressure loads using the smart skin
Regardless of over thirty years of research, tactile sensing still falls behind progress in computer vision methods. The reason for this discrepancy is that compared to cameras, tactile sensors must be compliant, tough and flexible enough to coat the surfaces of robotic limbs and hands

Summary

Introduction

Tactile sensing in human and animal skins enables them to touch, sense temperature, etc. The haptic perception, if added to robots, can significantly enhance their performance through better human-robot and robot-environment interactions. Even the most sophisticated robots have at most a few dozen tactile sensors. Regardless of over thirty years of research, tactile sensing still falls behind progress in computer vision methods. The reason for this discrepancy is that compared to cameras, tactile sensors must be compliant, tough and flexible enough to coat the surfaces of robotic limbs and hands. As the number of sensors increases, wiring and signal transfer become a major issue [1,2,3,4,5]

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Methods

Results