Research On Sector-Shaped Tactile Sensor Based On Constant Electric Field

Tactile is an important perceptual function when robots are in direct contact with the environment.It is one of the key technologies of robot development to develop the tactile sensor which satisfies the requirement.In the man-machine collision,the position coordinates detected by the tactile sensor can provide critical information for the emergency control to reduce the collision force and avoid the secondary collision.At present,the research of tactile sensor is mainly focused on array-structured sensor,but the array-structured sensor has the shortcomings of exist the dead zone and occupying more CPU resources.Non-array tactile sensors have the advantages of simple structure,good flexibility and being suitable for continuous detection.The disadvantage is that the shape of the sensor needs to be similar to or even the same as that of the robot link.This study is supported by the National Natural Science Foundation of China(no:51575111).Based on the distribution law of the constant electric field in the conductive layer,a sector-shaped tactile sensor was designed on the circular truncated cone which may be part of the robot link.First,the feasibility of constructing a unique and determined constant electric field on the conductive layer is analyzed from the principle of constant electric field,and the principle of detecting the position coordinates by two constant electric fields is introduced.According to the shape of robot link including circular truncated cone,the two-dimensional shape of the sensor is proposed and the design scheme of the sensor is proposed.The electric field distribution of the upper conductive layer and the lower conductive layer is determined depending on the electric field knowledge and the boundary value problem.The mathematical model is derived and the model of the position coordinate calculation is deduced.Secondly,the finite element analysis of the sensor was carried out using COMSOL Multiphysics software.The rationality and feasibility of the design are verified based on the constraints of the electrode,the simulation of the conductive layer and the simulation of the 3D model.When analyzing the detection accuracy,a series of simulations of the various contacts that the sensor may encounter using COMSOL Multiphysics software to analyze the sensor's error at position detection.Finally,a sample of tactile sensor was fabricated and subjected to a point contact experiment and an area contact experiment.The experimental results show that the design of the sensor is feasible,the sensor structure is simple and the detection accuracy can meet the requirement for detecting collision.The sector-shaped tactile sensor proposed in this paper can effectively cover the circular truncated cone of the robot link and accurately detect the contact coordinates.