TECHNIQUE TO HANDLE LOCAL CONSTRAINTS IN MULTIBODY DYNAMICS

摘要

Sometimes we have a system that can be expressed basically by independent variables, with some redundant variable groups to decide only small parts of the system respectively. If the constrains of these redundant variables in each group are not coupled with each other, namely these are no common variables, we call them as local constraints. Example of local constrains are Euler parameter constraint and constrains of link mechanism of car suspension system. The necessity of redundant variables can also be limited for position level. Within the simple nonholonomic system we can always select the appropriate independent velocities to express the other velocity level variables. If the system has only local constraints, it is inefficient to use the typical DAE formulation, which handled all the constraints simultaneously. The technique we explain in this paper has advantage in calculation time and also in the sense of constrain stabilization. This paper gives a basic idea of the technique and its general formulation. Also three examples are explained which we used to confirm the effectiveness of the technique. We got a good result of constrains stabilization. More detailed examination about the calculation time and the constraint stabilization is planned in near future before we proceed to construct a simulation program of complex elastic vehicle model.