Research On Virtual Robot-assisted Orthopedic Surgery System

In recent years, orthopaedics surgical robot technology has become one hot topic. However, operational objectives are human beings, so it raises the request about the interactive technique between the doctor and surgical robot. It's a key problem that prevents the research and development of the orthopaedics surgical robot. With the improvement of virtual reality and virtual reinforcement technology, robot-assisted orthopaedics surgical robot technology becomes a available way to solve the problem.This paper, combined with the China 863 Program as well as the National Natural Science Foundation projects, aimed at the human-computer interaction issues in the robot-assisted orthopaedics surgery, using virtual reality technology, tele-operate technology and modern medicinal image theory, researches virtual environment image modeling, human leg three-dimensional geometric model and soft tissue deformation in the robot-assisted orthopaedics surgical simulation. And a robot-assisted orthopaedics surgical simulation system has been built.In terms of Graphical modeling of virtual environment, we introduced the representation method of geometric model, combined with the actual situation in the subject, the paper proposed a novel method using Java3D and the Pro/E to establish a virtual environment modeling and robotics program, get the model of virtual environment bone surgery and robot, and kinematic analysis of navigation robot, C-arm and recovery robot, then researched on the corresponding collision detection. Used the creative lexical analyzer principle to extracte the approximated polyhedron information of the model's surface, expressed the entities with the sphere model. And analysed a variety of collision detection algorithm, combined with octree algorithm and the expression of sphere model, established the graphic collision detection module in the virtual environment.In terms of three-dimensional morphology of human legs, this paper discusses how to reconstruct three-dimensional geometric model of human legs based on medical CT images in detail. Using MC arithmetic, Gradient Mesh simplified arithmetic, arithmetic of cube model etc, some works have been finished, including obtaining medical cube data, taking out contour surface, simplifying mesh, constructing cube model and so on. Finally, assembly modeling together about human thighbone, cannon, leg skin based on CT images has been realized.In terms of biomechanical modeling of human legs, based on giving linear elastic model and nonlinear elastic model, this article discusses how to build multi-structure, multilayer and multi-material physical modeling and constructs finite element model of biological tissue of human leg. Base on biomechanical character of human tissue such as skeleton, muscle and skin, analyzing work of external force, boundary condition of biological tissue, this paper establishes static balance function and dynamic balance function of biological tissue, and supplies a theoretical method for calculation about deformation of biological tissue. Aimed at the problem of complexity of muscle dissection and difficulty of establishing model accurately, we raise a new modeling way based on morphology anatomy. This method considers biomechanical character of muscle tendon as well as microcosmic anatomy structure of muscle fibre. We process finite element simulation validation of human leg and then compare data of finite element simulation after calculating with data of forth location obtaining from body exemplar experiment, and inosculation of the data proves creditability of finite element model simulation of human leg.In the end, taking biomechanical modeling simulation of leg for example, it expounds some manipulation mode about development environment, control interface and surgical system of virtual surgery. To raise capacity that virtual surgical simulation system deals with real work, this article introduces BP NN model instead of finite element model, and realizes real-time biomechanical response. Then combining robot Assisted bone-knitting system, virtual surgical master-slave control test platform has been established. Using shunt-wound maser hand, manipulator inputs locomotion information and gets force feedback information. Virtual environment provides vision, calculates opposed tractive force and carries out force feedback experiments and virtual bone-knitting surgery experiments. The result of experiments testifies validity and usability of virtual surgical simulation system based on biology information.