Impulse-based Dynamic Simulation of Rigid Body Systems

Brian Vincent Mirtich

Ph.D. Thesis
University of California at Berkeley

download PDF:  MirtichThesis.pdf (5.7 MB)

download gzipped Postscript: (3.3 MB)



Dynamic simulation is a powerful application of today's computers, with uses in fields ranging from engineering to animation to virtual reality. This thesis introduces a new paradigm for dynamic simulation, called impulse­based simulation. The paradigm is designed to meet the twin goals of physical accuracy and computational efficiency. Obtaining physically accurate results is often the whole reason for performing a simulation, however, in many applications, computational efficiency is equally important. Impulse­based simulation is designed to simulate moderately complex systems at interactive speeds. To achieve this performance, certain restrictions are made on the systems to be simulated. The strongest restriction is that they comprise only rigid bodies.

The hardest part of rigid body simulation is modeling the interactions that occur between bodies in contact. The most commonly used approaches are penalty methods, followed by analytic methods. Both of these approaches are constraint­based, meaning that constraint forces at the contact points are continually computed and applied to deter­ mine the accelerations of the bodies. Impulse­based simulation is a departure from these approaches, in that there are no explicit constraints to be maintained at contact points. Rather, all contact interactions between bodies are affected through collisions; rolling, sliding, resting, and colliding contact are all modeled in this way. The approach has several advantages, including simplicity, robustness, parallelizability, and an ability to efficiently simulate classes of systems that are difficult to simulate using constraint­based methods. The accuracy of impulse­based simulation has been experimentally tested and is sufficient for many applications.



Due to the number of requests for electronic copies of Brian's thesis, I am currently hosting these files with Brian's permission.  -James

1997 - 2006 © James Kuffner, Jr.