Design And Research Of Soft Body Deformation Sensing Network Based On Fiber Bragg Grating

With the development of robotics technology,intelligent soft body,namely soft robot,has made up for the shortcomings of traditional rigid robot by virtue of its advantages of flexibility and security,and has become a new hot spot in the field of robotics research.At present,the research on soft robots is mostly about the design and research of motion control methods,mainly using open-loop control,but its effect is not ideal,so it has important research significance and application prospects to carry out real-time monitoring and detection of flexible deformation process of soft robots and realize motion information feedback.This paper combines the soft body with the optical fiber sensing technology,and through real-time perception and feedback of the movement position and shape parameters of the intelligent soft body,completes the shape detection of the robot body,realizes the closed-loop precise control of the flexible body with feedback link,in order to cope with multiple tests in complex environment.The main contents of this paper are as follows:(1)Soft grabbing robot is chosen as the prototype of this paper.This kind of intelligent soft body has a large aspect ratio.Its movement and deformation modes include bending,stretching and torsion.And the bending is the main deformation means,and its shape can be expressed by the continuous trajectory or discrete points of the center line.According to the piecewise constant curvature method,the motion model of soft body is established.The soft body is divided into several constant curvature segments,and connected with every segment to form a complete deformation shape curve.The limited measurement information is interpolated to obtain more parameter information and improve the accuracy of deformation curve reconstruction.Combining with the derivation process of the shape reconstruction theory of the soft body motion model,the dynamic data processing program of LabVIEW is compiled,and the shape curve of the soft body is simulated according to different scenarios,which verifies the feasibility of the reconstruction algorithm.(2)To solve the problem that the measurement range of quartz fiber grating can,t meet the demand of large strain measurement in the deformation process of soft body,the spiral arrangement of fiber grating is tilted to reduce the actual strain measurement of fiber grating and improve the measurement range of axial strain of soft body.Reasonable layout of circumferential sensor points is planned,and soft body deformation sensing network is designed to realize integrated detection of bending,expansion and torsion state parameters of soft body with large deformation.According to the strain equation of shape parameters measured by FBG,the processing program module of Lab VIEW measurement results is compiled.Combining with the previous dynamic data processing program,the visualization platform of soft body deformation curve is constructed.(3)A soft body deformation experiment platform was built,and the feasibility and good repeatability of FBG strain measurement were verified.By comparing the experimental results with the theoretical results,the feasibility and accuracy of the soft body deformation sensing network are verified,which indicates that the design of the soft body deformation sensing network is reliable and has practical value.The experimental error is analyzed,and the measures to reduce the error and improve the reconstruction accuracy are put forward.(4)The strain transfer model of surface-mounted FBG sensor is established,the strain transfer theoretical mechanism is deduced,and the strain transfer rate and average strain transfer rate along each point of the sensor scale are obtained.According to the theoretical formula,the effect of physical parameters of bonding layer on strain transfer is analyzed.The theoretical results are verified by finite element simulation.