Fully-Implicit Time Stepping Methods with Integrated Proximity Queries for Accurate Simulation of Multi-Rigid-Body Systems with Intermittent Contact

为了自动规划涉及对象之间接触的任务，对象运动的准确预测是必不可少的。应用包括人机协作操作、工业自动化、工程设计和计算机游戏的物理引擎。多体系统接触和粘滑行为的不确定性给稳定、准确地模拟多体系统带来了困难。商业上可获得的多体仿真软件甚至难以仿真具有接触的简单系统。因此，用户必须求助于试错法来找到产生可信但不一定准确的结果的模拟参数。 在这个研究项目中开发的算法将导致改进的未来版本的仿真产品，如亚当斯和Working Model.The主要来源的稳定性和准确性问题的多体仿真是多面体表示的光滑物体，解耦的碰撞检测的动态时间步进子问题的解决方案，库仑摩擦模型的线性化，和模型参数的误差。本研究的重点是公式，算法开发和分析的时间步进器，以消除前三个误差源。其结果将是一个完全隐式的，稳定的，准确的，优化的方法来模拟系统的刚性物体进行间歇性接触;对象将使用隐式和参数化的表面表示建模。没有以前的一般方法已经开发，结合动力学和几何约束，在一个完全隐式的方式。通过使用新的时间步进器作为"地面实况”模型，可以比较所有以前的模型，从而第一次可以量化最常见近似值的误差影响。这项研究将涉及研究生和本科生。结果将被纳入我们的模拟包，并在RPI的机器人课程介绍。外展活动包括夏季乐高机器人活动的中学生。

To automatically plan tasks involving contact between objects, accurate prediction of object motions is essential. Applications include collaborative human-robot manipulation, industrial automation, engineering design, and physics engines for computer games. The intermittency of contact and stick-slip behavior make it difficult to simulate multibody systems stably and accurately. Commercially available multibody simulation software has difficulty simulating even simple systems with contacts. As a result, users must resort to trial-and-error to find simulation parameters that yield believable, not necessarily accurate, results. The algorithms developed in this research project will lead to improved future versions of simulation products such as Adams and Working Model.The primary sources of stability and accuracy problems in multibody simulation are polyhedral representations of smooth objects, decoupling of collision detection from the solution of the dynamic time-stepping subproblem, linearization of Coulomb friction model, and errors in model parameters. This research focuses on formulations, algorithm development and analysis of time-steppers to eliminate the first three error sources. The result will be a fully-implicit, stable, accurate, optimization approach to simulating systems of rigid objects undergoing intermittent contact; the objects will be modeled using implicit and parametric surface representations. No previous general method has been developed that combines dynamics and geometric constraints in a fully-implicit manner. By using the new time-stepper as a ``ground truth" model, all previous models can be compared, so that for the first time, the error effects of the most common approximations can be quantified. This research will involve graduate and undergraduate students. The results will be incorporated into our simulation package and introduced in the robotics courses at RPI.Outreach activities include summer Lego robotics activities for middle school students.