UBC Theses and Dissertations
Parallel implementation of multibody dynamics for real-time simulation Wong, Darrell
A multibody dynamics formulation has been developed for the purposes of real-time simulation of large scale robotic mechanisms such as excavators. The formulation models the rigid body dynamics of any arbitrary tree structured mechanism, although at present the formulation is restricted to single degree of freedom rotational joints. This formulation is an example of the orthogonal complement approach, which describes the dynamics by projecting an initial description of the primitive equations of motion (the derivatives of translational and angular momentum plus the kinematic equations) from angular and translational Cartesian coordinates to relative angles. In this thesis the approach was developed from Newtonian and Eulerian principles. Novel single cpu algorithms for inertia matrix and force vector formation have been implemented. Novel multiprocessor algorithms were implemented for the inertia matrix and the force vector on a 2d [formula omitted] triangular mesh architecture. A feedforward systolic matrix solution technique was also implemented. These algorithms are of O(n) complexity, and together they form a parallel formulation which is more efficient than other parallel formulations in the literature for mechanisms with fewer than 15 degrees of freedom. A Caterpillar 215B excavator was simulated in real-time using an array of transputers, and teleoperation experiments were conducted to verify the formulation. Single cpu simulations of the PUMA 600 and a human torso were also conducted.
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