Research On Path Planning And Motion Control Method For Flexible Needle Insertion In Complex Environment

Percutaneous puncture surgery has been widely used in modern clinical practice.At this stage,clinical kidney puncture surgery is still at the stage of manual rigid needle puncture.The precise puncture method of kidney cancer targeted flexible needle in the robot automatic puncture scene has broad research and application prospects.Compared with the traditional manual rigid needle puncture,the robot automatic flexible needle puncture has shown great potential and advantages in improving puncture accuracy,reducing surgical risk and improving surgical efficiency.Aiming at the robot’s automatic flexible needle puncture in a complex environment,this paper proposes a new flexible needle puncture precise planning and compensation control method,and conducts simulation and experimental research.In order to obtain the optimal puncture path that satisfies the incomplete kinematics constraints of the flexible needle,this paper proposes an optimal path planning algorithm for the flexible needle based on the artificial potential field algorithm and the optimal arc fitting method in a two-dimensional environment.The algorithm constructs the entire puncture space into a comprehensive potential energy field through the gravitational field generated by the target and the repulsive force field generated by the obstacle,and takes the direction of the fastest drop in potential energy as the optimal needle-point entry direction to obtain an effective path point set.The needle point,the effective path point and the target point are sequentially connected through the arc path to obtain the reference path set containing all the smooth paths.Finally,the optimal path that satisfies the non-holonomic constraints of the flexible needle is selected from the effective path set through the path evaluation function.This algorithm can obtain the optimal planning path with variable curvature.Compared with the existing equal curvature and RRT path planning methods,the proposed algorithm can obtain a better puncture path.This paper also proposes a flexible needle closed-loop control algorithm based on fuzzy logic strategy to improve the safety and accuracy of flexible needle puncture.The fuzzy controller calculates the duty cycle change online according to the needle tip position error and the error rate of change to adjust the puncture trajectory.It can compensate for the needle tip deviation error caused by the uncertainty of soft tissue deformation,tissue heterogeneity,and calibration and control deviation.Effectively improve the control accuracy of flexible needle puncture.By adjusting one or more arc paths in the initial optimal planning path,the double arc fitting algorithm can also be used for online path planning.With the help of the online path planning algorithm to compensate the target drift during the operation and the fuzzy control algorithm to compensate the movement error of the puncture needle along the planned path,the target drift in the complex environment is effectively compensated,so that the target puncture accuracy of the flexible needle can be significantly improved.Multiple puncture experiments have been completed in agar gel imitations with similar mechanical properties to soft tissues.The experiments show that the flexible needle closed-loop control method proposed in this paper has better puncture safety and higher puncture accuracy in a complex environment.