Design And Research On 3D Simulation System For A One-legged Hopping Robot

With the rapid improving of robot technologies, hopping robots are widely used in many fields. 3D simulation platform of robots is very important in the research and applying of robots. In this thesis, kangaroo’s mechanical model was simplified to a one-legged hopping robot. Then, a 3D simulation system was designed based on researches of kinematics and visual model. The main research was consisted of four parts as follows.1. According to the characteristic of kangaroo’s mechanical model, it was simplified to one-legged hopping robot for research. Kinematic mathematic models were built according to the robot’s stance phase and flight phase. The problem of forward kinematics during the two stages was analyzed. The positive solution of kinematics was solved by transformational matrix method with D-H parametric. Real motion data were substituted into positive solution for discretization sampling. Then, linear fitting and simulation curve verifying were carried out in MATLAB. Based on the analysis of posture, differential sports and speed were studied. Jacobian matrix was also solved. Curve simulation verification was conducted for speed of tiptoe relative to body centroid during flight stage.2. Optimizing of real-time collision detection algorithm. The optimizing was carried out based on RECODE and OBB bounding box algorithm. A collision detection algorithm that based on image space was proposed in this thesis. This algorithm can be applied to large-scale complex scene and alleviate CPU’s burden as it utilized GPU acceleration technique. Two testing scenes were set according to the complexity of scene and models to carry out contrast experiment between RECODE and RAPID algorithms.3. The 3D simulation platform of the robot was developed in this thesis. Firstly, a 3D model was built for the one-legged hopping robot with 3ds Max software. Open source library, Assimp, was used for the import and display of 3ds model. Then, user interactive interface was developed with MFC library in order to achieve interface design between VC++ and OpenGL. UDP communication interface was designed for the 3D simulation platform. This can set up UDP communication connection with other PC in the local area network and achieve the call of MATLAB engine in VC++. As the background engine, MATLAB carried out numerical calculation and simulation curve plotting. This also added expansion interfaces for the secondary development of 3D simulation platform.4. Kinematics simulation experiment of the 3D simulation platform. A new generation method for the kinematics simulation animation that based on keyframe and interpolation algorithm was proposed in this thesis. This method had good teaching and demonstration functions. Through this method, users can set keyframe interactively and carry out kinematics simulation experiment on the simulation platform. Selecting appropriate interpolation algorithm for the space motion planning of joints during the flight stage should combine Cartesian space motion planning. In the end, simulation experiment of collision detection algorithm was carried out on the 3D simulation platform. Let the one-legged hopping robot impact with barrier during flight stage and then doing detection with optimization algorithm and OBB bounding box algorithm. It was innovative to apply this optimized algorithm in three-dimensional simulation system.