Multikollision

Multikollision is a term used in physics and computer simulation to describe a collision event in which three or more rigid bodies contact one another within a short interval of time. Unlike two-body collisions, multikollision involves several contact points and constraints that interact, potentially changing the post-collision state of the involved bodies in a nontrivial way. The term is used in domains such as computer graphics, robotics, vehicle dynamics, and crash analysis.

In simulations, multikollision is commonly addressed by two broad strategies: event-driven approaches that resolve contacts sequentially as they are detected, and time-stepping or constraint-based methods that enforce non-penetration and friction constraints across all active contacts within a time step. For multikollision, constraint-based formulations are widely used because they can capture simultaneous interactions and produce more stable results.

Key challenges include non-uniqueness of outcomes, sensitivity to contact graph structure, and difficulties in modeling friction and restitution consistently across multiple contacts. Numerical issues such as penetrations, jitter, and energy drift may arise. Typical remedies involve robust collision detection, regularization of contact constraints, stabilizing techniques (for example constraint stabilization or Baumgarte terms), and solving a linear complementarity problem or quadratic program to obtain contact impulses that satisfy non-penetration and Coulomb friction conditions.

Applications include real-time physics engines in video games, robotics simulators for planning and control, vehicle crash research, and computer graphics animation. Understanding multikollision is important for realistic interaction of stacked objects, dense debris, and complex contact networks where multiple bodies respond collectively rather than pairwise. See also multibody dynamics, contact mechanics, and friction modeling.