Modeling And Control On-line Of Minimally Invasive Surgical Robot Virtual Security Fixture

MIS surgeons often perform tasks on or nearby delicate tissues and organs while confined to a relatively small workspace. Because of the lack of haptic information and the fuzzy perception, it is easy to injure these delicate tissues accidentally. During MIS robot surgery, based on teleoperation, create a virtual security fixture for the vital organs of the body and control it in real-time to avoid the harm to the vital healthy tissues caused by surgeon's fatigue and mistake in operation. It prevent surgeon from entering the danger region and injuring the vital organs and tissues, relief the mental stress of the surgeon and make the surgeon to be able to focus their attention on solving the key technical issues in surgery. So the security of the surgery will be greatly enhanced.In this paper, based on the analysis of MIS robot system at home and abroad, the virtual sensor technology, as well as the key issues about virtual surgery technology makes an in-depth study on this topic.Established the monocular-vision based image digital module, using the implicit information of the MIS telerobot and magnified endoscopic image, calibrated coordinates of the important organs of the body on line.Sampled a series of feature points from the organ's surface of the body by using of manipulator to describe the external contour of the organ based on endoscope image, and then create a dynamic local geometric model of the virtual security fixture. Made a study on the existed algorithm about collision detection, proposed a combined method of improved Lin-Canny algorithm and Bounding Sphere algorithm, detect the collision happened in the virtual surgery, can meet the requirements of real-time detection. Based on spring-mass damper model, built virtual sensor for haptic detection between the surgical instrument and human organ in virtual surgery environment. Realized the tactile and force interaction between surgical instrument and human organ model, as well as the force navigation in surgery.Based on teleoperation, established the experiment platform of the MIS robot, the theory studied and methods were verified to examine the scientific nature, effectiveness and practicality of the virtual security fixture model and control algorithm.Virtual security fixture of MIS robot provide important guarantee for the security and reliability of MIS robot, so that minimally invasive surgery is more likely to be mastered by more surgeon. This technology not only can be used in robotic minimally invasive surgery, but also can be used in other robotic surgery, even for traditional open surgery. With further study, it will have a very good prospect.