Euler--Poincaré reduction and the Kelvin--Noether theorem for discrete mechanical systems with advected parameters and additional dynamics
This work provides a geometric discretization framework for systems with advected parameters, which is important for structure-preserving simulations in mechanics and control, but the contribution is incremental as it generalizes existing discrete reduction techniques.
The authors extend Euler-Poincaré reduction to discrete Lagrangian systems on Lie groups with advected parameters and additional dynamics, deriving discrete Euler-Poincaré equations and corresponding Kelvin-Noether theorems. Numerical simulations of underwater vehicle dynamics demonstrate the scheme's ability to preserve geometric properties over long time intervals.
The Euler--Poincaré equations, firstly introduced by Henri Poincaré in 1901, arise from the application of Lagrangian mechanics to systems on Lie groups that exhibit symmetries, particularly in the contexts of classical mechanics and fluid dynamics. These equations have been extended to various settings, such as semidirect products, advected parameters, and field theory, and have been widely applied to mechanics and physics. In this paper, we introduce the discrete Euler--Poincaré reduction for discrete Lagrangian systems on Lie groups with advected parameters and additional dynamics, utilizing the group difference map technique. Specifically, the group difference map is defined using either the Cayley transform or the matrix exponential. The continuous and discrete Kelvin--Noether theorems are extended accordingly, that account for Kelvin--Noether quantities of the corresponding continuous and discrete Euler--Poincaré equations. As an application, we show both continuous and discrete Euler--Poincaré formulations about the dynamics of underwater vehicles, followed by numerical simulations. Numerical results illustrate the scheme's ability to preserve geometric properties over extended time intervals, highlighting its potential for practical applications in the control and navigation of underwater vehicles, as well as in other domains.