具备触觉反馈的实时绳子打结仿真

Real-time Knot Tying Simulation of Ropes with Haptics

实现了实时绳子打结仿真。绳子使用刚性杆模型和FTL(FollowtheLeader)变形算法。碰撞处理算法将刚性杆当作圆柱体,使用AABB层次结构提高碰撞检测效率,可以处理绳子的自碰撞和绳子与其它刚体的碰撞,并通过设置临时接触约束实现等效摩擦力。通过碰撞簇的识别检测结的形成并在FTL算法中将结作为一个整体处理,确保结形成后可以在空间自由运动。图形绘制算法对刚性杆进行曲线插值以产生光滑的绳子效果。用户通过触觉反馈设备控制绳子的运动。反馈力根据绳子的张力和约束条件计算,并使用时间域上取平均的方法消除反馈力抖动现象。最后给出仿真程序的运行效果。

Real-time knot tying simulation of rope was implemented. The rope was modeled as a series of rigid links and FTL （Follow the Leader） algorithm was used for its deformation. To process self collision of the rope and collision between rope and other rigid objects, the rigid links were treated as cylinders and AABB bounding volume hierarchy was constructed and used to accelerate collision detection. Temporary contact constraints were set for collided rope parts to produce the effect of friction. Collision cluster detection was used to detect knot formation. Once detected, each knot was treated as a whole in FTL algorithm to enable it to move freely with the rest of the rope. To give the rope smooth appearance, the rigid links were interpolated using spline curves during graphics rendering. The user could control the rope by grabbing and moving part of the rope using haptic device. Feedback force was calculated according to tension in the rope and constraints applied to the rope. The feedback force was then averaged in the time domain to eliminate trembling. Finally the results of the simulation were given and discussed.