Research On Bi-planar Parallel Manipulator For Minimally Invisive Spine Surgery

Orthopaedic surgeries account for the largest amount number of clinical surgery operations, and the lumbar spine surgery is an indispensable branch. For the sake of sophisticated techniques and decreased trauma to the patients, the minimally invasive surgery(MISS) has grown in popularity in recent years. But due to the restricted perspectives and high risks, its further development and application has been limited. To increase the accuracy and the reliability of the surgical tasks, a novel robot-assisted system for the lumbar spinal surgery which is safe, reliable, and easy to operate is developed.According to the design acquirements of the system, the configuration of robot is set based on the macro-micro mechanism. The serial part is to achieve a large workspace and micro part is used to realize high precision positioning and surgeries operation. A detailed design of the bi-planar parallel robot is based on the module design methodology. It includes the bi-planar parallel module, the sleeve module, and the handle module. The intensity and dynamical modal of the proposed mechanism are analyzed.The kinematics model of the 5R mechanism is proposed, the inverse kinematics and forward kinematics are obtained. The design space is established and the corresponding theological workspace and singular loci are analyzed. The most inscribed workspace is defined and set as the criterion to assess the useable workspace. In addition, the stiffness performance and dexterity performance were given. Ultimately the parameter of each link was achieved based on genetic algorithms within the selected design space. The dynamic model of the 5R mechanism is analyzed, and several methods were proposed to improve the dynamic performance.The error factors which may have influence on the positioning of end point were analyzed. Firstly, the transfer function of dimension error is analyzed, and the transmission coefficient of each link is proposed. Secondly, the influence of clearance in pairs for the position error is given. Thirdly, the additional internal force of mechanism and deformation of link are calculated by using the matrix force method.Finally, the control system for minimally invasive spine surgery robot was designed. And the software was programmed to manipulate the motion of the robot based on visual C++ language. The experiments afterwards proved that the robot can satisfy the requirements of spine surgery.