EFFICIENT COMPUTATION OF ARTICULATED-BODY INERTIAS USING SUCCESSIVE AXIAL SCREWS

The articulated-body (AB) algorithm for dynamic simulation of chains o f rigid bodies was developed by Featherstone [1]. The most costly step in this algorithm is the computation of the AB inertias at each link which involves a spatial (6 x 6) congruence transformation. The amount of computation required is closely coupled to the kinematic modeling technique used, This paper examines this computation in detail and pre sents an efficient step-by-step procedure for its evaluation in a seri al chain with revolute and prismatic joints using nodified Denavit-Har tenberg parameters for modeling the kinematics. The result is a very e fficient procedure using successive axial screws that reduces the comp utational requirements of the AB algorithm by about 15% from results o btained by Brandl, Johanni, and Otter [2]. The procedure developed def ines a general approach and can be used to improve the efficiency of s patial congruence transformations of other types of matrices, such as spatial rigid-body inertias (used in the Composite Rigid-Body simulati on algorithm [3], [4]).