arXiv:2506.14097cs.ROcond-mat.soft2025-06

将刚体接触建模为递归生成的线性互补问题,避免了传统方法的采样误差和计算开销。

Smooth-Rigid-Body Contact as a ReLCP: A Recursively Generated Linear Complementarity Problem

  • 基于逐层添加单边约束,动态构建递增维数的LCP求解序列
  • 在小时间步下可保证有限终止,且接触不穿透误差可控
  • 适合高精度刚体动力学模拟,尤其适用于复杂几何体

本文将无摩擦光滑刚体间的非光滑接触问题重新表述为一种递归生成的线性互补问题(ReLCP),通过一系列维度递增的LCP求解实现。从经典的单约束共享法向符号距离(SNSD)LCP出发,仅在当前接触集预测的离散更新会违反光滑表面非穿透性时才添加单边约束。该方法直接作用于光滑几何,以预定容差强制满足非穿透性,避免了如网格化或多重球分解等代理表面模型固有的过度采样问题,后者常因几何保真度提升导致约束数量和计算成本急剧增长。对于严格凸体,在初始无重叠且时间步足够小时,证明了自适应增强过程的有限终止性,并得到唯一的离散时间速度更新。在小时间步极限下,对任意固定无重叠离散状态与固定几何重叠容忍度,递归将在首次求解后终止,退化为经典单约束SNSD LCP,保持补全时间步与底层微分变分不等式的一致性。数值实验包括椭球碰撞、紧凑椭球悬浮体压缩、细菌群落生长及张紧链甲网络,均显示稳定的大时间步行为、无离散化引入的表面粗糙度所导致的穿透控制,以及相较于代表性离散面补全形式显著降低的活动约束数量和运行时间。

原文摘要 · Abstract (English)

This paper reformulates complementarity-based time-stepping for frictionless nonsmooth contact between smooth rigid bodies as a recursively generated linear complementarity problem (ReLCP), involving a sequence of LCPs of increasing dimension. Starting from a classical single-constraint shared-normal signed-distance (SNSD) LCP, the method adds unilateral constraints only when the discrete-time update predicted by the current contact set would violate nonpenetration of the underlying smooth surfaces. The resulting procedure acts directly on smooth geometry, enforces nonpenetration to a prescribed tolerance, and avoids the oversampling inherent to proxy-surface contact models such as tessellations or multi-sphere decompositions, for which improved geometric fidelity can drive rapid growth in constraint count and cost. For strictly convex bodies, we prove that an initially overlap free configuration with sufficiently small timestep sizes, imply finite termination of the adaptive augmentation, and yield a unique discrete-time velocity update. In the small timestep limit and for any fixed overlap-free discrete state with a fixed geometric overlap tolerance, we prove that the recursion terminates after the initial solve, reducing the method to the classical single-constraint SNSD LCP and retaining the usual consistency of complementarity time-stepping with the underlying differential variational inequality. Numerical tests on colliding ellipsoids, compacting ellipsoid suspensions, growing bacterial colonies, and taut chainmail networks demonstrate stable large-timestep behavior, bounded interpenetration without discretization-induced surface roughness, and substantial reductions in both active constraint counts and runtime relative to representative discrete-surface complementarity formulations.

刚体动力学接触模拟LCP几何建模

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