Design Of A Novel Bevel Tip Needle And Research On Its Trajectory Planning

Percutaneous minimally invasive interventional treatment has no open bodytissue, the small therapeutic window, a wide range of treatment, the good treatmenteffect, the fast postoperative recovery, the small risk and many other advantages,which has been more and more used in clinical treatment for various diseases. Atpresent, the clinical interventional procedure adopts the rigid needle under theguidance of medical imaging equipment, making its tip reach the focal position ofthe body in pathological diagnosis and local treatment. Due to the nature of linearmotion, the rigid needle is limited in avoiding obstacles and selecting puncture path.However, the bevel-tip flexible needle which has the capacity of forming the curvepath is becoming the focus in medical treatment of minimally invasive surgery robotsystem since the outstanding obstacle avoidance ability in recent years.Owing to the lateral force perpendicular to pinpoint and the hyperelasticmaterial of the needle, the path of bevel-tip flexible needle is a circular arc ofdefinite radius during the movement in body tissues. Furthermore, the bendingdirection is determined by the position of bevel-tip. In recent research on flexibleneedle puncture, people usually rotate the base of needle to achieve the goal ofchanging the direction of bevel-tip. But, there will be some errors between the baseangle and the rotation of the tip angle because of the effect of friction producing bytissue and its internal flexible needle body, as well as the flexible needle materialproperties, which result in the deviations during the flexible needle puncturemovement within the organizations.This paper has designed a new structure of bevel-tip flexible needle based onpiezoelectric actuator. What’s more, we have done some work on the modeling,simulation and experiment, especially the trajectory planning based on the clinicaloperation conditions. Firstly, the force of flexible needle tip is analyzed during therotation in the tissue and we design a flexible needle whose tip and body isseparated. The new flexible needle’s tip is driven by shearing piezoelectricceramics.Secondly, the motion model which the flexible needle tip is rubbed in a planeis established by analyzing the different kinds of rolling conditions of the cylinderin a plane. Thirdly, the rub dynamics effect is analyzing under different waveformof voltage upon the piezoelectric ceramic. What’s more, some detailed analysis,calculation and simulation about a series of movement mode with respect to theeffect are established.After that, deeper research is done on the trajectory planning for the flexible needle in the tissue considering the application of the clinic. The axis feeding andcircumferential rotation of the needle’s motion in people’s tissue has beenseparately discussed and analyzed. The optimal path for the needle to the objectpoint has been proposed and simulated in the computer which has been discretizedand compensated based on the features of the needle feed system. And the trajectoryplanning strategy for the needle to pierce into the multilayer tissue is discussed.Finally, the experimental study is carried out in view of the theory cited above.Driven by piezoelectric ceramic under the action of outer voltage, the tip rotationmechanism under the new flexible needle structure is verified. According todifferent flexible needle rotation effects in view of different voltage waveforms,some research is discussed. Using the flexible puncture needle system, the flexibleneedle trajectory planning theory based on the clinical condition is verified.