Research On Natural Grasps In Virtual Reality And Its Assessment Method

In daily work and study,hand is one of the most important media for human to interact with the outside world.Therefore,if people can interact with objects in the virtual environment through virtual hands,it can effectively improve their immersion in the virtual reality environment.However,hand is a very complex organ in the human body and consists of bones,skin,muscles,etc.Thus,it is difficult to build an accurate virtual hand model to simulate the interaction behavior of the hand with virtual objects.As a result,in order to ensure the realtime and stability of interactive operations,the existing methods and techniques have to make some compromises in the realism of interactive behaviors.A virtual hand modeling method is proposed in this thesis to simulate the virtual hand interaction in the automobile virtual assembly training.Constraint rules in accordance with the characteristics of grasping behavior are established to replace the complex force analysis.The virtual hand model is integrated into the virtual assembly training,and a control experiment is designed for quantitative and qualitative evaluation on the interaction effect between the virtual hand and the object.The details are as follows:(1)This thesis analyzes the physiological structure of the human hand and establishes the mesh model and skeleton model of the virtual hand.The skeleton is bound to the geometric model of the virtual hand to make the mesh model deform with the change of skeleton posture.The virtual hand skin model is established,and particles with physical properties are bound at the position of the mesh model.Collisions and friction occur when the physical particles are in contact with objects and lead to real interaction.(2)From the view of mechanics,based on the contact information between the virtual hand and the object,the thesis establishes the grasping rules which accord with the characteristics of virtual assembly operation behavior.Constraint rules that prevent the penetration between the virtual hand and the object are established.By dynamically adjusting the stiffness value of the soft body,the thesis simulates that when the hand grasps the object hard,the contact surface between the hand and the object increases,and the grab will be more stable.(3)Based on the needs of the laboratory project,a virtual assembly training system is implemented by using the workpiece model provided by the project partner company,and the virtual hand model proposed in this thesis is integrated into the assembly training.A task-based experiment and control experiment are designed and the results are used for quantitative and qualitative evaluation.As shown by the experiments,the virtual hand model proposed in this thesis performs well in real-time interaction and stability,and is more consistent with the realworld interaction.