Research On 3D Forces Sensor Based On Mismatched Optical Fiber Structure

Multi-dimensional forces sensors refer to sensors that can simultaneously detect two or more directional forces/torques,and are widely used in fields such as intelligent robots,mechanical assembly,automobile manufacturing,and medical treatment.All-fiber Mach-Zehnder Interferometer(MZI)is an all-fiber interference structure,which has the advantages of high sensitivity,strong anti-interference ability and good stability in stress sensing.Therefore,a structure is designed The simple,three-dimensional force sensor with sensitive element as the core mismatch structure is of great significance.In this paper,single-mode fiber(SMF)-multimode fiber(MMF)-small-core fiber(TCF)-single-mode fiber(SMTS)is an all-fiber MZI sensor.The structure,combined with the spoke-type structure,constructs a three-dimensional force sensor with a core mismatch fiber structure,and studies it through a combination of theory and experiment.The main research contents are as follows:1.The development status of multi-dimensional force sensors at home and abroad is summarized,and the research status of multi-dimensional force sensors with optical fiber as the sensitive element is further introduced.2.The working mechanism of all-fiber MZI sensor is introduced.Combined with the strain sensing model of core mismatch fiber structure,the principle of stress sensing is analyzed.3.The finite element analysis software ANSYS Workbench is used to statically simulate and analyze the elastic body of the three-dimensional force sensor,and simulate the strain situation when the sensor is subjected to three mutually unidirectional forces in space.In the case of unidirectional force in the direction,the strain value of the center line of the upper surface of a group of beams along the y direction is always zero,and the value of the strain of the center line of the upper surface of a group of beams along the x direction is always the same,but the sign is opposite The area near the center cuboid has the largest strain value;when the sensor receives a single-dimensional force in the z direction,the strain curves on the upper surfaces of the four beams highly overlap,which indicates that the strain distribution on the upper surfaces of the four beams is the same.4.On the basis of ANSYS Workbench simulation,a multi-dimensional force sensor based on fiber core mismatch fiber structure is designed and produced.Paste the SMTS optical fiber structure at the corresponding position of the sensor,build an experimental test system,and test the performance of the sensor in three perpendicular directions in the space.The experimental results show that the sensor has good linearity and repeatability when external force is applied;The sensitivities in the three directions of x,y and z are:2 pm/N,1.9pm/N and 1.6pm/N.5.Combined with the results of sensor performance testing,decoupling algorithm based on linear calibration and least square method were used to decouple the calibration data of the three-dimensional force sensor when it received a single-dimensional force in the z direction.A set of data calibrated by experiment is decoupled by two methods.The decoupling results show that the decoupling algorithm based on linear calibration is closer to the actual value than the least square method in single direction force measurement,and the data decoupling performance is better.Therefore,this sensor selects a decoupling algorithm based on linear calibration for decoupling.Finally,a program that can be applied to the three-dimensional force sensor is written in the Matlab app to form a software display interface corresponding to the data of the multidimensional force sensor network.