Abstract

Figure 1: A Rube-Goldberg contraption that demonstrates many challenging multibody contact sounds. A noisy block feeder (Left) with flexible tubes ejects marbles into a double helix of plastic chutes (Middle), which causes a cup to fill up, lifting a lever that drops a bunny into a runaway shopping cart (Right) producing familiar clattering and clanging sounds due to deformable micro-collisions. Our approach can accurately resolve modal vibrations and contact sounds using an asynchronous, adaptive, frictional contact solver. Contact sound models based on linear modal analysis are commonly used with rigid body dynamics. Unfortunately, treating vibrating objects as “rigid ” during collision and contact processing fundamentally limits the range of sounds that can be computed, and contact solvers for rigid body animation can be ill-suited for modal contact sound synthesis, producing various sound artifacts. In this paper, we resolve modal vibrations in both collision and frictional contact processing stages, thereby enabling non-rigid sound phenomena such as micro-collisions, vibrational energy exchange, and chattering. We propose a frictional multibody contact formulation and modified Staggered Projections solver which is well-suited to sound rendering and avoids noise artifacts associated with spatial and temporal contact-force fluctuations which plague prior methods. To enable practical animation and sound synthesis of numerous bodies with many coupled modes, we propose a novel asynchronous integrator with model-level adaptivity built into the frictional contact solver. Vibrational contact damping is modeled to approximate contact-dependent sound dissipation. Results are provided that demonstrate high-quality contact resolution with sound.

Citations