Research On System Design And Control Methods For Percutaneous Surgery Robot

With the advantages of less bleeding,lower infections,fewer complications and smaller scars,minimally invasive surgery(MIS)enjoys fast development in the last 30 years.As a common and significant sector in MIS,the puncture procedure will always influence the final operation quality.Using surgical robot for percutaneous surgery is able to improve manipulation precision,reduce hand tremors and keep surgeon safe from radiation exposure,which has great research value.This project is about researches on a robot system for percutaneous surgery.The main content of this article includes the following parts.(1)Building a percutaneous robot hardware platformBy comparison the remote center of motion(RCM)implemented with a traditional serial manipulator,a percutaneous robot with intrinsic RCM mechanism is proposed in this article.The robot is composed of three independent parts including:a proximal Cartesian movement stage for positioning,a distal rotary arm for reorientation and a needle driving unit for penetration.(2)Motion planning and control of percutaneous robotKinematics and workspace of the mechanism are discussed to highlight its superiority in puncture situation.Based on the mechanism's stereotactic design,a novel entry point targeting plan is carried out by using two additional laser pointers mounted on the rotary arm.By restricting the movement of the robot toward certain direction,the superimposition of the remote center and the entry point can be rapidly achieved with only one single camera.This method may remove dependence of commercial trackers in the entry point alignment procedure at present.(3)Puncture process monitoring and puncture testDuring the operation,the robot is designed to work compatibly with two X-ray fluoroscopy devices which located at the top and on the side of the surgical table.An image based needle tracking method is introduced to assist real-time puncture path adjustment.In this method,line segment is chosen as the descriptor to represent the percutaneous needle.Combined with prior knowledge,basic image processing method Probabilistic Hough Transform is used to track the needle in motion.The method is validated its feasibility in off-line videos captured from both side image devices.In addition,the model of needle insertion force change is discussed and later tested in ex vivo experiments conducted by the robot.