Key Technical Research On Motion Planning And Motion Synthesis For Virtual Human

Motion control for virtual human is one of the most important aspects in such areas as VR (Virtual Reality) -based ergonomics and maintenance engineering. It has two key problems: motion planning and motion synthesis. Both the theoretic and the practical research on the above two problems are carried out in this thesis, funded by Weapon and Equipment Advanced Research project"VR-based Maintainability XXX System", National"863"project"Advanced Integrated Developing Technology for High-quality Heavy Business Truck", and National Lunar Exploring project"Navigation and Control for Lunar Rover Vehicle". The main content include: the RRT (Rapidly-exploring Random Tree) based path planning algorithms, proof of probabilistic completeness of the RRT algorithms, the manipulation planning methods for the arm work and the upper-body work, as well as the motion synthesis methods based on motion primitives. The outcomes of the research will improve the efficiency and the realism of the virtual human motion simulation, which is of great importance to both the theoretic research and the application in the field of ergonomics and maintenance engineering.The main contributions and innovations are as following:1. An adaptive multi-RRTs algorithm has been proposed to effectively address the narrow passage problems, in which a Bridge-Test algorithm has been improved to accurately identify narrow passages in configuration space, and an adaptive tree selection strategy has been established by random combinatory optimization algorithm from reinforcement learning. The performance of the proposed algorithm is dramatically improved compared with that of the traditional RRT algorithms. The RRT-based path planning algorithm has been applied to address the path planning problem for the walk task of virtual human in the project"VR-based Maintainability XXX System". Typical applications show that the proposed algorithm can be generalized to address the path planning problem of lunar rover vehicle.2. In the research of probabilistic completeness theory of RRT algorithm, traditional RRT algorithms and the adaptive multiple-RRT algorithm have been proved to be probabilistic complete firstly. Next, the expansion process of the adaptive multiple-RRT algorithm has been proved to be optimal based on the analysis of the property of the random combinatory optimization strategyεt-greedy.3. A uniform RRT based manipulation planning framework for virtual human has been proposed. The math model of a uniform feasible configuration space is described, based on which the RRT-based arm and upper-body manipulation planning algorithms have been proposed. Regarding the problem of upper-body manipulation planning, the RRT algorithm is applied to rapidly solve the inverse kinematics problem. Thereafter, a sample-project algorithm has been proposed to solve the problem of motion constraints of manipulated object. EDMAN (Engineering Digital MAN), a cross-platform virtual human motion simulation software has been designed and implemented to address the problem of the virtual human maintenance task simulation in the project"VR-based Maintainability XXX System". The experimental results show that the application of the proposed algorithms has dramatically improved the efficiency of the virtual maintenance simulation.4. A virtual human motion synthesis framework has been proposed based on HMM motion primitives. In the process of the motion primitive modeling, firstly, a weighted PCA algorithm, as well as a clustering algorithm based on Gaussian Mixture Model (GMM), is adopted to segment the motion capture data into motion clips. Secondly, a hierarchical HMM clustering algorithm has been proposed to implement the classification and the modeling of the motion primitives. In the process of motion retrieval and synthesis, a dynamic programming algorithm based on HMM similarity measurement has been proposed to retrieve the motion clips and sort them according to the time sequence. The above motion synthesis method has been applied to address the problem of the truck ingress/egress motion simulation, which makes contributions to the accomplishment of the project"Advanced Integrated Developing Technology for High-quality Heavy Business Truck".