Modeling And Control Of Magnetic Resonance Imaging Compatible Pneumatic Surgical Robot

According to the demands of the high-end treatment equipments, combining thekey technologies of surgical robots and taking the minimally invasive prostate needleinsertion surgery as the typical application, a prototype of five-degrees-of-freedommagnetic resonance imaging (MRI) compatible pneumatic surgical robot has beendeveloped. Theoretical analysis and experimental verification have been conductedbased on the robot system. The main contents contain modeling of mechanicalsubsystem, modeling of control subsystem, construction of co-simulation platform,verification of movement accuracy and test of system compatibility. The researchcontents and related contributions are described as follows:Firstly, a novel MRI compatible pneumatic surgical robot for prostatebrachytherapy has been built based on hierarchical modular design with constitutingfeature of Scott-Russell mechanism. Mechanical subsystem model of the robot systemhas been established: the kinematics of the manipulator is analyzed by D-H methodand vector method, and the forward and inverse equations of the manipulator arederived; dynamics analysis of the manipulator is performed by virtual work principleand the mapping relationship between the cylinder driving force and joint position,velocity and acceleration is described. Those laid the foundation of realizing motioncontrol of the robot system.Secondly, control subsystem has been established based on hybrid drive methodwith combination of pneumatic actuation and ultrasound motor actuation. Themathematical model of valve-cylinder is constructed. The established controlsubsystem model is linearly parameterized and the model parameters are identifiedusing the ‘system identification toolbox’ in MATLAB. Stability analysis is alsoproposed with the modeled plant through the use of Nyquist criterion, which providesa strong guarantee for the realization of motion control.Thirdly, the proportional-integral-derivative control strategy is proposed basedon the mechanical and control subsystem model, and co-simulation is foundedaccording to the ADAMS and MATLAB software. A virtual prototyping based onco-simulation platform is constructed to verify the effectiveness and correctness of theestablished system model and the designed controller.Finally, experiments have been carried out to test the function of the robot, such as performance of the pneumatic servo control system, motion accuracy of thesurgical robotic system, system compatibility and so on. The soft tissue experimentshave also been conducted to verify the correctness and rationality of the proposedtheoretical analysis.The above researches accomplished in this thesis are very meaningful forpromoting the MRI compatible minimally invasive surgical robot research andimproving our capacity in the competitive high-end treatment equipments industries.