Tech Preview - Generalized Hybrid Solver and Fast Friction Model
- Marc Lievin
The Generalized Hybrid Solver Extension provides a method of improving the performance of some simulations by reducing the fidelity in the calculation of specified friction forces.
Using the Generalized Hybrid Solver
The generalized hybrid solver can use both direct and iterative methods to solve the dynamics simulation problem. The standard solver of Vortex uses a direct method of solving. The direct method is more accurate but it can get slowed down drastically for problems with many contacts with friction. An iterative solver can be faster for such problems at the cost of lower fidelity. The generalized hybrid solver works in conjunction with the Fast Friction option of contact materials. Friction for contacts that have Fast Friction enabled are solved using an iterative method whereas the rest of the problem is solved with a direct method.
To use the generalized hybrid solver, the Generalized Hybrid Solver extension must be added to a mechanism in the simulation. This extension affects the simulation globally, not just the mechanism which contains it, so only one instance of this extension should be present in the simulated content.
The extension has two inputs: “Enable Solver” and “Number of Iterations”. Increasing the number of iterations can improve fidelity but increase the solve time.
The materials in the material table have a parameter for Fast Friction with three settings: Deactivated, Activated and Neutral. These settings are used to determine if Fast Friction is enabled for a material pair. The Fast Friction setting can be overridden for a specific material pair. When set to Neutral, the setting for the other material in contact is used. Neutral - Neutral and Deactivated - Activated pairs default to Deactivated.
If using multiple solver groups, or the automatic solver groups extension, note that the Generalized Hybrid Solver only supports the Point Force Coupling option. If the Generalized Hybrid Solver is enabled, it will automatically change the coupling method to Point Force Coupling.