Real-time System Development And Control Strategy For Minimally Invasive Surgical Robot

Minimally invasive surgery has advantages of small wound, less pain and shorter recovery time. It has been widely performed in clinical application. But there are drawbacks such as lack of hand-eye coordination and flexibility. Robot-assisted minimally invasive surgery system produced by the combination of robotics and minimally invasive techniques can overcome these drawbacks, and improve the operation efficiency and effectiveness significantly.Minimally invasive surgical robotic systems are used in clinical application, which claims high real-time and safety requirements. And s urgical robot system needs to achieve that surgical instruments follow doctor hands in the same movement trend, which guarantees the hand-eye coordination. In this paper, software and hardware framework of minimally invasive surgical robot is built based on the QNX real-time system, and the master-slave consistency incremental control strategy in Cartesian space is studied. These two parts form a complete control system. Finally, a variety of experiments are carried out on the control system to verify the effectiveness and performance of real-time control strategy.The distributed I/O and processing control system architecture is adopted. It has to be ensured that the real-time performance of each part of the system must meet the needs of the whole system. QNX system is ported to the IPC, and a communication network among various parts is built up. The application software system is designed based on the hierarchy architecture. According to various functions, the system is partitioned into tasks. Prioritize real-time tasks and define the structure of them. The real-time performance of the system is analyzed with rate monotonic analysis method. The results show that the control system has good enough real-time performance to meet the requirements of minimally invasive surgery.For the master-slave heterogeneous structural characteristics of the surgical robot system, the master-slave consistency incremental control strategy in Cartesian space is studied. A D-H parameters model of slave robot arms is established, and the analytical solution of inverse kinematics is obtained according to structural characteristics of the arm. And the master-slave consistent mapping method in endoscope perspective is studied. The orientation relationship between arms is measured quickly and accurately with the monocular vision technology. In order to improve the perfo rmance of surgical robot system, intraoperative master-slave adjustment, the master Tremor filtering and intraoperative virtual fixture are developed as master-slave control functions.The real-time performance comparison experiment, master-slave control experiment, suture and knot experiments and surgery on living animal are carried out. Experiment results show that the slave robot arm could follow the motion of master manipulator with good real-time performance; control system could enable the operator intuitively complete a variety of surgical procedures in hand-eye coordination; masterslave control functions improve the stability, flexible and security of the robotic system. The experiments have laid a solid foundation of the clinical application with minimally invasive surgical robot.