Research On CT Image Guided Manipulator For Lung Interventional Operation

This paper focus on manipulators for lung interventional operations under CT(Computed Tomography)image guidance.After analyzing the restrictions on structural dimension and imaging compatibility in CT bore,according to the actual operation process,the works,including structural design,structural analysis and hardware control system development,would be carried out.The main research contents and achievements are as follows:Firstly,according to design requirements,tendon-sheath transmission system is selected to make the manipulators compact and compatible;poly formaldehyde and carbon fiber are used to fabricate the several components.In the way of the modular design method,several modules are design for different functional requirements,including automatic seeds implantation module,biopsy module,position module and automatic transferable bed.By combination of different modules,the biopsy robot with tendon-sheath transmission system is developed.Secondly,based on screw theory,the kinematics model of the biopsy robot is built.Meanwhile,forward kinematics,inverse kinematics and reachable workspaces are deduced.After Jacobian matrix analysis,to avoid multi-solution problem under singularity configuration,each module of biopsy robot is driven to adjust needle position in turn.Structure error and actuation error are main error sources that affect the accuracy of the robot.They are regarded as special screw motions to build error model,simulation results prove that the error model is effective to improve precision.Lastly,by comparing the methods of electronic circuit,single chip computer and PLC(Programmable Logic Controller),the hardware control systems of stepper motor and servomotor are developed based on single chip computer to accomplish miniaturized,easily adjustable goals.After the single DOF(Degree of Freedom)tendon-sheath experiment,the position error is less than 0.55 mm.Laser tracker system is used to test the precision of the robot,the main error of needle tip is 1.254 mm,which is accurate enough to replace manual operation.