虚拟手抓持规则融合策略研究

A virtual hand grasping rule fusion strategy

群体虚拟手抓持规则是虚拟手和虚拟物体进行抓持操作的交互规则,用于判定虚拟手是否能够成功抓持物体。对基于几何的虚拟手抓持规则和基于物理的虚拟手抓持规则分别进行了研究,针对基于几何的虚拟手抓持规则规则简单、仿真效果较差,基于物理模型的虚拟手抓持规则计算复杂、难以实现实时仿真的问题:(1)改进基于几何的虚拟手抓持规则,通过接触点位置、法矢和抓持面法矢制定抓持规则,使其效果逼近力封闭虚拟手抓持规则;(2)利用力封闭计算中抓持接触点和法矢不变的特性,通过内力配比避免了抓持操作中的非线性规划求解,使抓持操作阶段实现实时仿真;(3)通过几何约束进行初始抓持判断—力封闭计算校正—内力配比力封闭计算的策略,实现了完整的抓持过程实时仿真。设计的交互实验说明该抓持规则能实现高沉浸感和实时性的抓持仿真,可以应用到虚拟训练、虚拟装配等仿真平台。

Virtual hand grasping rules are interaction rules for a virtual hand and the virtual object to perform grasping operations.It’s used to determine whether the virtual hand can successfully grasp the object.We study geometry-based virtual hand grasping rules and physics-based virtual hand grasping rules respectively.The former rules are simple but the simulation effect is poor.The latter rules are complicated to calculate and difficult to implement real-time simulations.In view of the above problems,(1)we improve geometry-based virtual hand grasping rules,and formulate the gripping rules by the contact point position,the normal vector and the gripping’s surface normal vector to make the effect approach to force closure virtual hand grasping rules;(2)based on the invariability characteristic of the closed contact point and the normal vector in the force closure calculation,we avoid the nonlinear programming solution in the grasping operation by the internal force ratio,and realize real-time simulations in the grasping operation stage;(3)through the strategy of“initial grasping judgment based on geometric constraint-force closure calculation correction-internal force ratio for force closure calculation”,we realize real-time simulations of complete grasping operation.We design interaction experiments to verify that the proposed grasping rule can achieve high immersion and real-time grasping simulations,and it can be applied to simulation platforms such as virtual training and virtual assembly.