Linköping University Electronic Press

Title:	Integration of Collision Detection with the Multibody System Library in Modelica
Authors:	Vadim Engelson
Series:	Linköping Electronic Articles in Computer and Information Science ISSN 1401-9841
Issue:	Vol. 5 (2000), No. 010
URL:	http://www.ep.liu.se/ea/cis/2000/010/

Abstract:	Collision detection and response is one of the most difficult areas in simulation of multibody systems. Two known approaches, the impulse-based method and the force-based (penalty) method, can be applied for multibody simulation in Modelica. The impulse-based method requires instantaneous modification of some variables, but such modification is not always possible in Modelica. The force-based method leads to stiff ODE, which can be handled by solvers used with Modelica. We suggest a new way to express the penalty coefficients. The force-based method, however, requires computation of penetration depth which is time-consuming. We also suggest a method that combines the distance between bodies and the penetration depth into a single quantity used for force computation. Calling external functions is a preferable method integrate collision detection algorithms with practical physical models, since body geometry is stored externally. We describe an interface with collision detection tool SOLID.

Abstract:

Collision detection and response is one of the most difficult areas in simulation of multibody systems. Two known approaches, the impulse-based method and the force-based (penalty) method, can be applied for multibody simulation in Modelica. The impulse-based method requires instantaneous modification of some variables, but such modification is not always possible in Modelica. The force-based method leads to stiff ODE, which can be handled by solvers used with Modelica. We suggest a new way to express the penalty coefficients. The force-based method, however, requires computation of penetration depth which is time-consuming.

We also suggest a method that combines the distance between bodies and the penetration depth into a single quantity used for force computation.

Calling external functions is a preferable method integrate collision detection algorithms with practical physical models, since body geometry is stored externally. We describe an interface with collision detection tool SOLID.

Original publication 2000-12-05	Postscript part I -- Checksum Checksum (old) Information about recalculation of checksum Postscript part II -- Checksum II Checksum II (old) Information about recalculation of checksum

LiU Electronic Press