Structural Analysis And Control Of Multi-needle Continuous Seed Implantation Device

As the people’s standard of living improves,cancer rates and mortality also increase year after year.Radioactive seed implantation surgery has become an effective method of treating cancer because of its high targeting,small traumas,precise curative effect and low side effects.However,conventional seed implantation surgery requires frequent replacement of needle sheaths and seed capsules,resulting in poor surgical effectiveness and physician fatigue.For this purpose,this paper designs a multi-needle continuous seed implantation device.From a dynamic perspective,the factors affecting the continuous motion of the device were simulated and analyzed,and the corresponding control system was designed.Model experiments allowed to check the feasibility of the design of the device,the continuity of movement and the high efficiency of the work.First of all,the analysis of the procedure,the characteristics and the requirements relating to the implantation of radioactive seeds allowed to summarize the design requirements of the multi-needle continuous seed implantation device.According to the design requirements,the design and analysis of the overall configuration diagram was completed,and the workflow of the multi-needle continuous seed implantation device was planned.Based on the workflow and modularization idea,the structure design of the needle-changing sheath module and the seed-changing module,after that,the statics simulation of the key parts were completed,and the mechanical motion cycle diagrams were designed respectively,which verified the rationality of the motion process.The design requirements of the docking mechanism are analyzed to explain the design of the structure and the operating principle of the docking mechanism.Furthermore,the overall structural design of the multi-needle continuous seed implantation device was completed.The device can simultaneously carry multiple needle sheaths and multiple seed capsules to achieve automatic and continuous implantation of seeds.Secondly,the ANSYS Workbench finite element simulation analysis software is used to obtain the deformation of the needle core by gravity.According to the deformation results,the needle core model is optimized,the needle core guide hole is designed,and the dynamic simulation is used to obtain the needle core’s stress during movement.The force change curve and stress cloud diagram at the time of collision are obtained by dynamic simulation,and the reliability of needle core motion is verified.According to the Monte Carlo method,the motion errors of the needle sheath and the seed capsules during the replacement process were calculated,the calibration mechanism was designed to reduce the errors,and the maximum angular acceleration allowed by the calibration mechanism was calculated.SOLIDWORKS Motion and Simulation are used to analyze the force changes of the docking mechanism during the docking,needle removal and separation stages,and obtain the stress and strain cloud diagram at the maximum force,which verifies the reliability of the docking mechanism.Then,based on the analysis of the control requirements of the multi-needle continuous seed implantation device,the functional block diagram of the control system was planned,the construction of the lower computer system and the development of the upper computer software based on Labview were completed,and the communication strategy between the upper and lower computer and the robot is analyzed.The acceleration and deceleration motion control of the stepper motor is realized through the bezier curve,and the stationarity of motion of the multi-needle continuous seed implantation device is improved.Finally,a model experimental platform was built to record the time it takes for the multi-needle continuous seed implantation device to implant seeds into the target point,and the model experimental data was juxtaposed and fitted.The model experimental results showed that the device can function continuously,compared with the traditional single-needle seed implantation surgery,effectively reducing the time of the seed implantation surgery improves the effectiveness of the surgery.