가상 중심 메커니즘을 이용한 치과 임플란트 수술 보조 로봇에 관한 연구

Abstract

Implant surgery is generally accepted as the good technique to replace the teeth completely. Regardless of the technical progress, the "freehand" drilling of implant is performed frequently in the numerous implant surgery. This procedure suffers from the shortcoming that the surgeon has to rely solely on his imagination to match the CT images with the real situation at the patient and that hand tremble of dentist is a insolvable problem. The simple surgical templates support the drilling. They provide easy handling but do not allow for any intraoperative modification of the predefined implant positions and orientations. The navigation in dental implantology is highly reliable and accurate systems. Although navigation facilitates positioning, the image guided adjustment of the angulation cannot be attained easily. Furthermore, the trembling cannot be substantially eliminated by mere computer assisted navigation. A completely alternative way could be a robot. Surgery is a highly interactive process and many surgical decisions are made in the operating room. The goal of surgical robotics is not to replace the surgeon with a robot, but to provide the surgeon with very versatile tools that extend his ability to treat patients. Many surgical tasks are characterized by relatively large angular mobility about a single point or within a limited spatial volume. These considerations have led us to develop mechanisms that naturally decouple rotational and translational motions of tools at a point apart from the mechanical structure of the robot. Many surgical robots include such a virtual center mechanisms as circular motion. In VC mechanisms, the RCM point is defined and mechanically locked by the kinematics of the mechanism. In this dissertation, assistant robot for dental implant surgery using virtual center mechanism is studied. It is a semi-active system that can perform a task by human-machine cooperative manipulation. The double parallelogram linkage is applied for the VC mechanism which circles a remote-center-of-motion point. Its design is verified by the finite element analysis and the multi-body dynamic analysis. The F/T sensor is used as the joystick for driving a VC manipulator. The F/T sensor signals are filtered by using zero offset, box averaging, decoupling gain, dead zone and saturation algorithms, and are transformed into motor input signals. The performance of a developed VC manipulator is evaluated. Yaw angle of handpiece according to input signals of motor3 is measured. Travel and hysteresis of a VC manipulator are also obtained. Alignment algorithm is introduced to align a RCM point with a drill tip by vision sensor and movement of drill tip is observed.