Flexible Tactile Sensor Array for Slippage and Grooved Surface Recognition in Sliding Movement.

Wang Wang,Mei Mei,Chen Chen

doi:10.3390/mi10090579

Abstract

Flexible tactile sensor with contact force sensing and surface texture recognition abilities is crucial for robotic dexterous grasping and manipulation in daily usage. Different from force sensing, surface texture discrimination is more challenging in the development of tactile sensors because of limited discriminative information. This paper presents a novel method using the finite element modeling (FEM) and phase delay algorithm to investigate the flexible tactile sensor array for slippage and grooved surfaces discrimination when sliding over an object. For FEM modeling, a 3 × 3 tactile sensor array with a multi-layer structure is utilized. For sensor array sliding over a plate surface, the initial slippage occurrence can be identified by sudden changes in normal forces based on wavelet transform analysis. For the sensor array sliding over pre-defined grooved surfaces, an algorithm based on phase delay between different sensing units is established and then utilized to discriminate between periodic roughness and the inclined angle of the grooved surfaces. Results show that the proposed tactile sensor array and surface texture recognition method is anticipated to be useful in applications involving human-robotic interactions.

Highlights

Flexible tactile sensors have been widely utilized in robotics, prosthetic hands, and medical surgery [1,2]
Robotic dexterous manipulation generally requires integrated tactile sensors on the robotic hand with force sensing as well as object texture and contour shape recognition abilities
To fill this research gap, we developed an accurate 3D finite element modeling (FEM) model of the tactile sensor array to study the sensing performance and contact behavior of the sensor when contacted with objects

Summary

Introduction

Flexible tactile sensors have been widely utilized in robotics, prosthetic hands, and medical surgery [1,2]. Youssefian et al [17] developed a finite element modeling (FEM) of the tactile sensor by adopting nonlinear elastic material properties to study the induced stress and strain when a normal force is applied to the outer surface of the tactile sensors In these proposed numerical models, the structure of the tactile sensors needs to be simplified into beam and plate structures for fast calculation convergence. Based on the measured contact forces of the tactile sensor array, a novel approach based on phase delay algorithm for grooved surface recognition is developed and verified by both FEM modeling and experimental validation.

Flexible Tactile Sensor Array

FEM Modeling

Slippage Detection in Sliding Movement

Phase Delay Algorithm for Surface Texture Recognition

Spatial Period Discrimination

Inclined Angle Calculation in Grooved Surfaces