Research On Mechanical Properties Of The Elastic Body Of A Six-Axis Force Sensor Based On Strain Gauge

With the improvement of robot’s intelligent level, the requirement for multi-axis force sensor is higher and higher. So an accurate mathematic model of this kind of force sensor should be established if a comprebensive knowloge of it is needed. At present the modeling approaches used widely about multi-axis force sensor are experimental method and numerical method. But these two methods have a common shortcoming that they can not reveal the nature relationship between the force applied on the sensor and its deformation, stress and strain. However, analytical method can solve this problem. So it is of great significance to establish the mathematical model of the force sensor by using analytical method. This thesis is funded by the National Natural Science Foundation Project of "Research on Dynamic Coupling Characteristics of A Six-Axis Force Sensor Based on Strain Gauge (NO.51175001)". The main aim of this master thesis is to establish an accurate mathematical model about the mechanical properties of the six-axis force sensor by using analytical method. In this paper, the main research methods and research work are as follow:(1) In static analysis, according to the structure characteristic of the six-axis force sensor based on double layer E-type membrane, decompose the sensor into elastic part and rigid part. The rigid part is equivalent to the boundary condition. The force applied on the sensor is moved to the elastomer equivalently and then the force model of the elastomer is obtained. Then the static characteristic of the force sensor can be derived and simulated based on the theory of material mechanics and elasticity mechanics.(2) According to the difference of the elastomers’ shape, different methods are used to analyze their free vibration. For the free vibration of the lamella, Rayleigh-Ritz method and variables separation method are adopted to derive the approximate solution of the nature frequencies and corresponding mode shapes. The analytical solutions of free vibration of the membranes are deduced according to the nature of Bessel functions. Both the analytical results are simulated with MATLAB.(3) Based on the analysis of the elastomers’ free vibration, the analytical expressions of the elastomers’ dynamic deflection are studied when a single sinusoid force is applied on the six-axis force sensor. Then according to the theory of Fourier Series and Fourier Transform, the forced vibration can be analysed when arbitrary force changing over time is applied on the sensor.(4) According to the force situation of the force sensor in actual work, decompose a force in any directions into six components in space, and then the force situation of the force sensor is obtained.The main innovation of this paper is abandoning the commonly used experimental method and numerical method and replacing them by analytical method to establish the sensor’s static model, to deduce the related parameters of the elastomers’ free vibration and the dynamic deflection expression of the elastomers’ forced vibration.