Research And Optimal Design Of The Variable Stiffness Manipulator In Single-port Surgical Instrument

As an important stage in the development of minimally invasive surgery(MIS),single port surgery(SPS)not only has the same therapeutic effect as traditional laparoscopic surgery,but also has many other advantages,including slight trauma,less pain,short hospitalization,no scar and so on.Compared with natural orifice transluminal endoscopic surgery(NOTES),SPS has a wider range of application.Nowadays,researches about the SPS system have made remarkable progress.However,most of the existing systems can't achieve both sufficient flexible workspace and high load capacity.Based on the low melting point phase change metal(PSM),this paper explains the mechanism design,kinematic and workspace analysis and optimal design of the driving platform.The main content of this paper is shown as following:Firstly,according to requirements of instruments in operational process,a variable stiffness manual operating platform for SPS is designed.Variable stiffness insertion sheath(VSIS)module and drive module of the flexible manipulator are introduced and described in detail.The design efficiently improves movement flexibility and spatial accessibility,thus bringing great convenience in adjustment.In addition,the variable stiffness insertion sheath increases the load capacity of the manipulator and provides a stable platform.Secondly,based on actuator space,virtual joint space and workspace,the kinematic model is established by using a kind of geometric analysis method,which is both efficient and practical.And the workspace simulation is accomplished.According to length variation of the steel length,the mapping between the instrument arm and the driving handle is presented.The overall structure and design parameters of the driving handle are optimized by using particle swarm optimization(PSO).Finally,based on conceptual design and analysis of the variable stiffness manipulator,evaluation tests of stiffness characteristic and workspace determination are designed to verify the effectiveness of the proposed design scheme and the correctness of the kinematic model.The error of VSIS under the comprehensive impact factors is measured by an experiment.