A coordinate partitioning framework with iterative refinement for coupled multibody dynamics and hydraulic systems

Abstract

Real-time simulation of constrained multibody systems is challenging due to complex constraint networks and strong nonlinearities arising from coupled domains. In coordinate partitioning formulations, updating dependent coordinates is often the dominant computational cost and significantly affects numerical robustness and accuracy. This thesis develops and evaluates efficient numerical strategies for dependent coordinate updates and extends them to real-time simulation of nonlinear hydraulically coupled multibody systems.

A unified framework is established to assess three update strategies: exact update, Newton increment, and Newton-Raphson, applied to planar and spatial benchmark mechanisms. Profiling indicates that dependent coordinate updates account for 60–90% of the total runtime, motivating targeted optimization.

To improve scalability, a global coordinate partitioning approach with iterative refinement is introduced. Numerical results show that it achieves accuracy comparable to relative-coordinate semi-recursive formulations while significantly reducing computational cost.

Finally, a coupled multibody hydraulic formulation is proposed. Iterative refinement is applied to both independent coordinate integration and constraint enforcement, avoiding conventional nonlinear solvers. The results demonstrate reduced computational effort while maintaining accurate constraint satisfaction and energy-consistent behavior.

Overall, the thesis provides practical guidelines for selecting update strategies under real-time and high accuracy requirements, and introduces refinement-based techniques that enhance efficiency and robustness in multi-physics multibody simulations.