Research On Force Sensing Technology Based On Fiber Bragg Grating

As one of the important external sensors,the robot multi-dimensional force sensor,is usually mounted on the wrist or ankle of the robot and can be used to sense the external contact force.The robot multi-dimensional wrist force sensor enables the robot to accurately control its posture and motion,which requires the sensor to have small cross-axis sensitivities,good static and dynamic characteristics,and high sensitivity.With fiber Bragg grating being its sensitive element,the sensor can be used in harsh environments such as strong electromagnetic interference and high humidity and high salt,which can meet the requirements of the robot on special occasions.Firstly,two kinds of multi-dimensional force sensor elastic structure models based on fiber Bragg gratings are studied.The static,modal and transient characteristic of a multi-dimensional force sensor elastic body is obtained by using ANSYS finite element analysis software.According to the static simulation analysis,the stress and strain of the elastic body are obtained when the sensor is subjected to single-dimensional force/torque in all directions.The modal analysis of the sensor elastomer is carried out to know the vibration characteristics of the elastic structure,and the natural frequencies and modes of the first six orders are given.Transient analysis of the sensor elastomer yields the deformation of the elastic structure under dynamic loading.Secondly,the overall scheme of the force measurement system is designed based on fiber Bragg grating.The main components such as ASE light source,FBG,optical circulator and fiber optic connector used in the hardware part of the system is introduced in detail.The optical signal is converted into an electrical signal by the FBGA demodulation module,and the data is collected by the control circuit,and the communication between the upper computer and the hardware is realized by the USB port,thereby transmitting the data to the upper computer for processing.The upper computer interface includes two parts of upper computer management and web-page monitoring,and the two parts of data are transmitted through a database.Finally,the bow beam elastic body was customized,the arched beam elastic body is customized,and the experimental system is built.According to the laboratory conditions,thearc beam elastic body is simulated,and the fitting relationship between the central wavelength variation and the force of the fiber Bragg grating is determined,and the sensitivity is obtained.It proves that it has good repeatability and stability,which proves that the system is feasible.