Key Techniques Of 6-PTRT Parallel Robot And Their Applycation In Orthopaedic Surgery

Currently, internal fixation is widespread to treat fracture of thighbone and tibia, while there are still some problems such as long surgery duration, low precision, hard work and deleterious radiance to doctors. During last decade, robot-assisted surgeries have been implemented in applications and are becoming the research focus all around the world because of its advantages, e.g. enhanced accuracy, short operation duration, and minimal invasiveness to the patient. By virtue of high mechanical stiffness and precision parallel robot is widely used in the robot-assisted orthopaedic system. So it has important theoretic significance and actual application value to investigate the key techniques of parallel robot in robot-assisted neoplasty.This work of this thesis is sponsored by China National High Technology and Development Program (863) projects entitled"Tele-operation assisted bone-setting surgery robotic system"and"Research and development of long-distance robotic tele-surgery systems". For the sake of establishing a 6-PTRT parallel robot system which can restore bone after fracture of the thighbone and tibia and investigate the key techniques of such robot and the method of diaplasis.Based on the comprehensive analysis of the restore fracture bone method, 6-PTRT parallel robot has been chosen as the mechanism, and the design target is proposed. The kinematics of such kind of parallel robot is introduced, and the parallel robot system has been built.Some key problems about 6-PTRT parallel robot have been investigated: the work-space of Hooke joint in parallel robot has been analyzed to get the criteria for design and safety purposes. The three-plane method is proposed to measure the pose of parallel robot, and in accordance with this method, the kinematics equation of the robot is calibrated. The parallel robot's force feeling static model and related issues can be used to judge if the links are safe in any cases.Based on the medical knowledge, some fracture diaplasis methods with aid of the robot have been proposed: the method based on image processing, the method based on physical line traction and the fuzzy control method based on biomechanical model of human leg. Some experiments and simulation have been executed with the fracture diaplasis surgery platform and parallel robot. Experimental results show that the method based on image processing is more accurate but the requirement with respect to the fixing is higher. Accuracy of the method based on physical line traction is slightly lower with a moderate requirement with respect to fixing, therefore it's more applicable for real application. The fuzzy control method based on biomechanical model of human leg avoids the steps of constantly taking X-rays to test the effect of diaplasis in "one-dimensional compression", so the radiation dosage of the doctors and patients can be reduced while the efficiency of operations will be improved.The work of this dissertation will provide theoretical and practical experiences for the investigation of parallel robot, diaplasis methods and human biomechanical in computer-assisted orthopaedic system, and will be helpful in the field of orthopaedics especially.