Study On Robotic Control Technology For Accurate Puncture Under Respiratory Motion

Puncture robot has been widely used in neurosurgery,orthopedics and other clinical fields.But its application in puncture surgery under respiratory movement still faces great challenges.The target area of chest and abdomen is affected by respiratory movement,thus its position changes in real time.If target puncture is performed directly according to preoperative image data and planned path,the puncture accuracy is not only low-level but the pull between needle and surrounding tissue will lead to the bending and deformation of needle and tissue damage.Therefore,how to overcome the influence of breathing movement and improve the location accuracy of the target area is the focus of research on the effective application of puncture robot in thoracic and abdominal part.At present,puncture robot is mainly used in the puncture of rigid target area.It matches the data of fiducial markers in preoperative medical image space and actual operation space to complete one-time precise puncture.However,the position of target areas in chest and abdomen changes due to the influence of respiratory movement.As a result,the intraoperative and preoperative image information cannot be accurately matched,leading to low puncture accuracy on the non-rigid target areas under respiratory movement.Due to the complex characteristics of respiratory movement such as periodic but asymmetric,if robot cannot analyze the respiratory movement signal in real time,calculate the optimal time slot for puncture,and adjust the movement posture accordingly,it will lead to the pull between the surgical tool and the patient tissue,resulting in secondary injury.In view of the above problems,this paper completes the corresponding research contents:(1)A puncture robot system under respiratory movement is designed.In order to achieve accurate puncture of target area under respiratory movement,a puncture robot system under respiratory movement was constructed in this paper.Combined with the near-infrared optical tracking system,six-degree-of-freedom robotic arm,experimental device for the simulation of respiratory motion and robotic software control center,the software and hardware system of the puncture robot under respiratory movement is constructed.Experimental device for the simulation of respiratory motion outputs respiratory motion signal in real time,which provides an effective verification platform for relevant algorithms and technologies.(2)A multiple closed-loops hand-eye calibration algorithm for puncture robot is proposed.In the process of hand-eye calibration,the manipulator moves along its base and end coordinate frame with a specific movement strategy.During robotic movement,the position information of the markers mounted on the surgical tool is collected by the optical tracking system.The algorithm inputs the position data of markers and outputs the relative position relationship between different coordinate frames in the puncture robot system.It uses the closed-loop transformation principle of coordinate frame to calculate the closed-form solution without iterative calculation cycle,which greatly reduces the risk of non-convergence in calculation and shortens the calculation time of target parameters,as well as avoids complex mathematical derivation and calculation.The experimental results show that the multiple closed-loops handeye calibration algorithm can be accurately calibrated with a small amount of input data,and the location accuracy on the static target area is less than 1 mm,which can be effectively applied to the hand-eye calibration of puncture robot system.(3)The target location algorithm with geometric constraints in three-dimensional space and the uncalibrated SR-UKF target location algorithm are proposed.An accurate,safe and robust mathematical model for target location based on geometric constraints in threedimensional space is established,which can calculate the target robotic pose and increase the safety factor during puncture process.This algorithm calculates the target coordinate system firstly,and then obtains the target robotic pose through the closed-loop transformation of coordinate frame.The position and posture of surgical tool coincides with the preset puncture path after rotation and translation according to the spatial geometric constraints.In order to improve the applicability of the puncture robot in clinical scenarios,the uncalibrated SR-UKF target location algorithm is studied in this paper.Preoperatively,the system does not need to perform hand-eye calibration but uses SR-UKF algorithm to online estimate the target robotic control pose and realize the angle and position location of puncture path.In this paper,a series of experiments are carried out to verify the feasibility of the above target location algorithms.(4)The strategy of robotic movement on respiratory follow-up movement and target puncture is proposed.The robotic control center acquires the respiratory motion signal in real time and calculates the optimal time slot for puncture.The robot performs target puncture or respiratory follow-up according to the optimal time slot.At the optimal time slot,the robot advances the needle into the target area.When in the non-puncture time slot,the robot stops the needle insertion into the target area and follows the breathing movement.The error of target location upon the experimental device for the simulation of respiratory motion by using this strategy is less than 3 mm,which meets the requirements of clinical target puncture in chest and abdomen.