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Viyom Vivek

Publications and source records attributed to Viyom Vivek.

3 recordsLinked to original sources

Geometric Integrators for Nonholonomic Systems on Lie Groups

We present a general framework for constructing structure-preserving numerical integrators for nonholonomically constrained mechanical systems evolving on Lie groups using retraction maps. Retraction maps generalize the exponential map and provide a convenient tool for performing numerical integration on manifolds. In nonholonomic mechanics, the constraints restrict the dynamics to a nonintegrable distribution rather than the entire tangent bundle. Using the Hamel formulation, the equations of motion can be expressed in local coordinates adapted to this constraint distribution. We then specialize the framework to the case of Lie groups, where both the dynamics and the constraints exhibit symmetries, allowing a simplified formulation of the numerical scheme. The resulting integrator respects the constraint distribution and enforces the nonholonomic constraints at each discrete time step. The approach is illustrated using the Suslov problem.

math.NA

A Geometric Approach to Structure-Preserving Integrators for Mechanical Systems

We develop a geometric framework for the numerical integration of mechanical systems evolving on manifolds. After briefly reviewing classical numerical methods and highlighting their limitations and shortcomings in non-flat (non-Euclidean) spaces, we include a short interlude reviewing the differential geometric notions required in the sequel. We then introduce retraction maps as intrinsic generalizations of the Riemannian exponential, which induce discretization maps tailored to manifold-valued dynamics. Adopting the Tulczyjew unified viewpoint, mechanical systems are formulated as Lagrangian submanifolds, providing a natural and coordinate-free foundation for the construction of structure-preserving integrators for both Hamiltonian and Lagrangian systems. The framework is specialized to Lie groups, where parallelizability allows for the global trivialization of tangent and cotangent bundles and the systematic derivation of integrators for Euler-Poincare and Lie-Poisson equations. The effectiveness of the proposed approach is illustrated through the rigid body and heavy top, and is further extended to the construction of a geometric integrator for an underactuated mechanical system-a quadrotor-demonstrating the applicability of the framework beyond fully symmetric systems and toward problems relevant in robotics and control.

math.GM

Numerical Integrators for Mechanical Systems on Lie Groups

Retraction maps are known to be the seed for all numerical integrators. These retraction maps-based integrators can be further lifted to tangent and cotangent bundles, giving rise to structure-preserving integrators for mechanical systems. We explore the particular case where the configuration space of our mechanical system is a Lie group with certain symmetries. Here, the integrator simplifies based on the property that the tangent and cotangent bundles of Lie groups are trivializable. Finally, we present a framework for designing numerical integrators for Euler- Poincare and Lie-Poisson type equations.

math.NA