Research On Flexible Tactile And Sliding Composite Sensing Based On The Fiber Bragg Grating

Bionic robot is the key support equipment in advanced manufacturing industry.Robot tactile and sliding intelligent sensing technology is the key technology for robot to capture the external information and achieve human-computer interaction.Based on the fiber Bragg grating with small volume,fast response speed and strong anti-electromagnetic interference capability,this paper adopted a combination of theoretical analysis,finite element simulation analysis and experimental study to carry out a comprehensive and in-depth study on the flexible tactile and sliding sensing composite sensing problem.The research and analysis of the tactile and sliding sensing theory under encapsulation condition was completed based on the sensing theory of fiber Bragg grating.The double-layer cruciform sensing array unit was proposed,and the packaging model was built and the sensing simulation experiments were carried out.The system platform of tactile and sliding sensing experiment was built,and a series of temperature and tactile and sliding sensing experiments were designed and completed.According to the experimental results,the algorithm model is used to complete the temperature compensation of the tactile sensing experiments and the recognition and classification of the sensing signals in the sliding sensing experiments.The main research contents of this paper are as follows:1)Based on the fiber coupled mode theory,the basic sensing theory of fiber Bragg grating is studied.The mapping rules of temperature,strain,pressure with the central wavelength of the grating are analyzed,and the temperature-strain cross-sensitivity mechanism is clarified.Based on the theory of material mechanics and elastic mechanics,sensing signal and numerical analysis model is established,and the theoretical models of pressure and shear force of tactile and sliding sensing in FBG flexible polymer encapsulation were constructed.The pressure sensing mechanism in tactile sensing and the friction sensing mechanism in sliding sensing were studied,and the mapping rule between wavelength drift and measured parameters of the polymer encapsulated sensing grating was revealed.2)According to the requirement of flexible tactile and sliding sensing,a double-layer cruciform distributed FBG sensing array unit was designed and proposed by using the multi-parameter signal sensing method of fiber Bragg grating.A polymer encapsulation model was built,and the optimal embedding position of the double-layer structure was determined by finite element simulation analysis.The temperature,pressure and shear force of the package model were simulated and analyzed,and the stress distribution along the corresponding path of the sensing grating is analyzed.The prototype of single and double cruciform array tactile and sliding sensors were designed and developed by using the FBG encapsulation technology.3)In order to verify the performance of tactile and sliding sensing of the sensor,the experimental system platform of temperature and tactile and sliding sensing were built.The temperature and tactile and sliding sensing experiments were designed and completed by using the FBG flexible tactile and sliding sensor designed and developed.According to the numerical analysis of the experimental data,the pressure sensitivity of the sensing gratings in the single cruciform sensor is 0.0525nm/N and 0.0579nm/N,and the shear force sensitivity is 0.0536nm/N.The average percentage error of tactile measurement calculated by repeated experiments is within 3.77%,which verifying the repeated stability of the sensor.The average temperature sensitivity of the sensing gratings in the double cruciform sensor is 13.001pm/? and 12.937pm/?,which is1.3 times that of the bare fiber Bragg grating.The pressure sensitivity of the gratings is0.0265nm/N,0.0293nm/N,0.0227nm/N and 0.0259nm/N,and the shear force sensitivity is 0.0602nm/N and 0.0636nm/N.The experiments of different sliding directions and sliding velocities were completed with the control variables,and the response curves of the sensing grating with different sliding directions and velocities were obtained through the sliding sensing signals,so as to judge the different sliding states.4)In order to optimize the performance of the tactile and sliding sensor,based on the adaptive fuzzy neural network model,a network model was built to compensate the temperature for the influence of non-standard parameters in the tactile and sliding sensing experiments.The results show that the sensing errors are greatly reduced after the compensation,and the sensing grating reference errors are all reduced to within2.92%.In order to classify and characterize the characteristic information of the sliding sensing experiment,the sliding characteristic quantity was extracted based on the sensing signal of the grating wavelength,and the sliding direction and velocity were identified and classified by using the empirical mode decomposition and support vector machine algorithm model.To sum up,the research of flexible tactile and sliding composite sensing was carried out in this article based on optical fiber Bragg grating.The proposed flexible tactile and sliding sensor can realize the detection of temperature,pressure,shear force and sliding information,which lays a certain foundation for the application of this sensor to the field of robot tactile and sliding sensing,and has certain theoretical and practical significance.