Research Of Intraoperative Spinal Motion And Compensation For Robotic Orthopedic Surgery System

In all kind of orthopedic operation,pedicle screw fixation is one of the most common operations.However,it is wide considered as one of the most dangerous and difficult operations due to the special anatomic structure of vertebra.Therefore,robotic auxiliary surgery(RAS)has been introduced in spinal surgery by many researchers.But there is a huge challenge which restricted the clinical application of RAS.Firstly,the vertebra would fluctuate during operation.The fluctuation,caused by respiration and heartbeat,would reduce the precision and safety during drilling screw path.The mainly research in this thesis is to build the predicting model of a certain vertebral segment’s positional deviation.Based on the traditional operative procedure,a standard operative procedure for robotic assisted spinal surgery had been designed.The safety of operation is strongly influenced by spinal fluctuation.Then a data collection system was built,and the system is mainly made of two parts: the motion collection module(MCM)is used to track and record the three-dimensional motion of vertebrae,and the tidal volume collection module(TvCM)is used to record the volume of inhaled gas.Because the experimental signals have a lot of noise,FFT and DWT were used to process the noisy vertebral positional signals.The appropriate wavelet basis function for a certain signal was selected based on the performance in de-noising,and the performance is assessed by root mean square error decision-making method.Because the variation of chest’s volume is deemed as the immediate cause of spinal fluctuation,a physical model consisted of two partial overlapped ellipses was built to imitate the structure of chest.The intersection of ellipses is considered as a certain vertebral segment,and the PSO algorithm and the de-noising data is used to obtain the coefficients of intersection’s expression.The coefficient of determination(R2)was used to assess the data fitting performance.Based on 3-PRS parallel platform and Robotic Spinal Surgery System,three sets of comparing experiments were conducted and the thrust force of drilling is reserved by force/torque sensor.In statistical terms,the maximum force recorded in the tests with active compensation is steadier,which means the safety of robot assisted surgery can be guaranteed with compensation.