| Targeted puncture surgery has the advantages of small wounds and quick recovery,and is favored by patients.In prostate brachytherapy,radioactive seed implantation and lesion biopsy require flexible needle puncture.Compared with steel needles,flexible needles have higher flexibility.It is difficult to accurately control the effective deflection of the flexible needle by manually inserting the flexible needle during the puncture process.Robot-assisted puncture mainly uses intermittent rotation of the needle shaft to control the bending curvature of the flexible needle.In this paper,the force and bending model of flexible needle puncture soft tissue is established by applying lateral driving force,and the influence of lateral driving force on the bending curvature of flexible needle is analyzed,which has important research significance and application value.A method for multi-sensor fusion to feedback the curvature of the flexible needle is proposed.Design a fiber Bragg grating embedded flexible needle structure,and embed the fiber sensor into the flexible needle.The optical fiber sensor collects the wavelength change of the flexible needle during the puncture process,reconstructs the shape of the needle body of the flexible needle,and accurately obtains the bending curvature of the flexible needle during the puncture process.This paper proposes a needle tip steering method based on lateral driving force.A lateral drive mechanism is designed to apply a lateral drive force between the support mechanism and the needle entry point to compensate for the radial deflection of the flexible needle.The lateral driving force is applied near the insertion point of the flexible needle to provide a corrective force for the flexible needle shaft.The puncture state of the flexible needle can be adjusted by changing the size of the lateral driving force.Research on the force received by the FBG embedded flexible needle in the process of puncturing the bionic tissue.The mechanical models of clamping force and clamping friction force,cutting reaction force,lateral driving force and lateral driving friction force,tissue resistance and friction resistance are established,and the influence of lateral driving force on other components is analyzed.The mechanical model of each component force is solved through experimental data,and the relationship between the lateral driving force and other component forces is obtained.According to the established mechanical model,the Rayleigh Ritz method is used to establish the bending model of the FBG embedded flexible needle puncturing the tissue,establishing the bending deformation model of the flexible needle puncturing the soft tissue after the lateral driving force is applied,and predicting the different and different lateral driving forces.The influence of the applied position on the bending trajectory of the flexible needle and simulation verification in ABAQUS.Build an experimental system for puncturing tissue with FBG embedded flexible needles,and complete the puncture experiment.The experimental data is compared with the flexible needle bending model,and the error is within the allowable range,which proves the rationality and accuracy of the model established in this paper. |
