Spatial Operator Algebra for Multibody System Dynamics 1

This paper describes a new spatial operator algebra for the dynamics of general{topology rigid multibody systems. Spatial operators allow a concise and systematic formulation of the dynamical equations of motion of multibody systems and the development of e cient computational algorithms. Equations of motion are developed for progressively more complex systems: serial chains, topological trees, and closed{loop systems. New operator factorizations and expressions for the mass matrix and its inverse are derived and used to obtain e cient, spatially recursive computational algorithms. The algorithms can be easily recon gured in response to changes in the constraints and the topology of constituent bodies. Thus, they are particularly suited for time{varying multibody systems. References are provided for extensions to exible multibody systems. Spatially recursive algorithms, based on the sequential ltering and smoothing methods encountered in optimal estimation theory, provide the computational infrastructure to mechanize the spatial operators.