mingwu-li / forward

A COCO-based shooting (differential-correction) toolbox

A COCO-based shooting toolbox for dynamical systems

This repo presents a shooting toolbox for autonomous and non-autonomous dynamical systems.

It supports dynamical systems in both the first-order and the second-order forms. In particular,

• For first-order systems, numerical integration solvers of MATLAB are used for performing forward simulation.
• For second-order systems, Generalized alpha and Newmark integration schemes combined with Newton's iteration are used for performing forward simulation.

Automatic construction of adjoints for first-order systems is supported as well. Please refer to [1-2] for more details about the automatic generation of adjoints.

This toolbox can be used to solve two-point boundary-value problems with arbitrary boundary conditions. For example, it can be used to perform the continuation of periodic orbits. The variational equations are solved as a by product to obtain the Jacobian for the iterations of fixed points of Poincare maps. Applications of this toolbox for computing the forced response curves of high-dimensional mechanical systems with distributed nonlinearities can be found in [5-6] (1320 DOFs).

This toolbox is developed in the platform COCO (continuation core). For more details about COCO, please refer to [3-4].

When you use this toolbox and want to cite it, you may use the following

<@misc{coco-shoot, author = {Li, Mingwu and Dankowicz, Harry}, title = {A {COCO}-based shooting toolbox for dynamical systems}, howpublished = {\url{https://github.com/mingwu-li/forward}}, note = {Accessed: xxxx-xx-xx} }>

References

[1] Li, M., & Dankowicz, H. (2018). Staged construction of adjoints for constrained optimization of integro-differential boundary-value problems. SIAM Journal on Applied Dynamical Systems, 17(2), 1117-1151.

[2] Li, M., & Dankowicz, H. (2020). Optimization with equality and inequality constraints using parameter continuation. Applied Mathematics and Computation, 375, 125058.

[3] https://sourceforge.net/projects/cocotools/

[4] Dankowicz, H., & Schilder, F. (2013). Recipes for continuation. Society for Industrial and Applied Mathematics.

[5] Jain, S., & Haller, G. (2022). How to compute invariant manifolds and their reduced dynamics in high-dimensional finite element models. Nonlinear Dynamics, 107(2), 1417-1450.

[6] Li, M., Jain, S., & Haller, G. (2022). Nonlinear analysis of forced mechanical systems with internal resonance using spectral submanifolds, Part I: Periodic response and forced response curve. Nonlinear Dynamics. https://doi.org/10.1007/s11071-022-07714-x

forward's Issues

Examples for automous systems

Hello,

Is it possible that you could provide an example for continuation of periodic orbits for an autonomous system? I see there is no constructor for HB2forward, unless I am misunderstanding.

Warm regards,
James