The purpose of this book is to present computationally efficient
algorithms for calculating the dynamics of robot mechanisms represented
as systems of rigid bodies. The efficiency is achieved by the use of
recursive formulations of the equations of motion, i.e. formulations in
which the equations of motion are expressed implicitly in terms of
recurrence relations between the quantities describing the system. The
use of recursive formulations in dynamics is fairly new, 50 the
principles of their operation and reasons for their efficiency are
explained. Three main algorithms are described: the recursIve
Newton-Euler formulation for inverse dynamics (the calculation of the
forces given the accelerations), and the composite-rigid-body and
articulated-body methods for forward dynamics (the calculation of the
accelerations given the forces). These algorithms are initially
described in terms of an un-branched, open- loop kinematic chain -- a
typical serial robot mechanism. This is done to keep the descriptions of
the algorithms simple, and is in line with descriptions appearing in the
literature. Once the basic algorithms have been introduced, the
restrictions on the mechanism are lifted and the algorithms are extended
to cope with kinematic trees and loops, and general constraints at the
joints. The problem of simulating the effect of contact between a robot
and its environment is also considered. Some consideration is given to
the details and practical problems of implementing these algori?hms on a
computer.