Research On A New Tactile Sensor Based On Fiber Bragg Grating

Tactile perception is an important function of sensing information changes for organisms.Similarly,the robot also needs the tactile sensing function to accurately identify the size,stress,temperature,material and shape of the contact target.With the rapid development of intelligent robots,the types and number of tactile sensors required gradually increase,which will bring a series of problems such as electromagnetic interference,complex integration and signal noise.Fiber Bragg grating tactile sensor has the advantages of small dimension,high sensitivity,low cost,biocompatibility,and immune from electrostatic and electromagnetic noise,it is widely used in the field of tactile sensing.A new tactile sensor based on fiber Bragg grating(FBG)is studied in this paper.Firstly,aiming at the problem that doctors lack the force perception information of contact between surgical instruments and human tissues in minimally invasive surgery,a new structure of FBG tactile sensor is proposed,the first innovation of the new structure is to fix a spoke-type cross beam structure near the tip of the needle column,and to make double circular arc cutting on both ends of the traditional elastic beam;The second innovation in the new structure is to dig a grooves on the surface of the needle column.Through the force simulation and comparative analysis,the force strength of the new structure has been improved.The torque force sensing element FBG1 is pasted on the upper surface of the new elastic beam to calibrate the torque force strain,and the axial force sensing element FBG3 is pasted into the groove to calibrate the axial force strain.Secondly,aiming at the influence of temperature on the reflected center wavelength in the force tactile sensing experiment,a reference fiber method is proposed to compensate the temperature.The reference element FBG2 is pasted on the under surface of the new elastic beam,and only one end point of the grating is pasted.,FBG2 only feels the temperature change and it is not affected by the stress.The difference between the reflected center wavelength of the sensing element and the reference element can reduce the interference of temperature,and improve the force sensing performance of the new FBG tactile sensor.Finally,the torque force,axial force and temperature sensing performance of FBG new tactile sensor are also studied.The experimental data of reference fiber method are analyzed,the resolution and sensitivity of torque force are 0.8mN·m and 22.8pm/mN·m,respectively;the resolution and sensitivity of the axial force are 0.03N and 0.089nm/N,respectively.Through the analysis of the force tactile sensor performance data and comparing the performance of other similar studies reported data,it shows that the new FBG tactile sensor has good force tactile sensing performance,which enables doctors to enhance the perception of small force strain in minimally invasive surgery,and it can not only sense the axial force strain in puncture surgery,but also the strain of small torque force,so as to improve the safety and reliability of surgery.