Research On Design And Control System Of Afterloading Robot For Brachytherapy

Afterloading technology is an important branch of brachytherapy, which has become hot topic of tumor therapy research. Sponsored by Tianjin Science and Technology Support Plan Key Projects, the main purpose of study is to develop afterloading brachytherapy robot with independent intellectual property rights. This paper involves design of mechanical structure, manufacturing, construction of transmission system and control system, and also some related research on key technical problems, such as transmission and source positioning accuarcy. Research presented in this paper can be summarized as the follows:Firstly, In order to meet the purpose of afterloading brachytherapy, Systematic analysis of key transmission mechanism of robot was done, improved transmission mechanism was proposed based on prior analysis. Then the overall mechanical structure design was determined, subsequent conceptual design, detailed design of subsystem was finished. The 3-D virtual model of prototype was built, 2-D digital engineering drawing further lay the technical groundwork for robot prototype construction.Secondly, the analysis of control system was done regarding functionality of robot, after preliminary design of control system, hardware control circuit was built, key control program of PLC was developed. Debugging of control subsystem and mechanical system was performed, smooth feeding motion and retraction motion of cable, precise treatment channel selection function was achieved.Finally, the static model of cable and catheter was built considering open-loop cable transmission characteristics and friction, flexibility of cable. theoretically deduced the factor affecting cable positioning accuracy. After construction and testing of robot prototype, experiment was set up to study cable positioning accuracy, the result was consistent with theoretic analysis, which validated theory.The research result presented in this paper is of significant theoretical and application value, which provide design methodology reference for relevant radiotherapy robotic systems, and lays a good foundation for further research.