Nested algebraic loops

Nested algebraic loops

Sometimes, some submodels are embedded in more than one loop: in this case we are talking about nested loops. Nested algebraic loops can occur in models involving central submodels like an interface import block or a chassis submodel.

For example, FMU import blocks are generally strongly linked to the system they are embedded in and generally have multiple variables at I/O interfaces.

Figure 63: Example of a FMU import submodel involved in two nested algebraic loops

Now consider the example of the chassis submodel VDCAR3DOF2 in 04 _ModularModel demo.

Figure 64: 04_ModualModel demo sketch

The chassis submodel is embedded in a system containing two different algebraic loops, which can be displayed from the compilation window.

Figure 65: Compilation window for 04_ModularModel

Navigating through the two loops, only the upper elements providing the lateral force on front axle and front tires are emphasized even if the chassis model is also part of the corresponding loop.

Figure 66: First algebraic loop display in 04_ModualModel demo

The second loop will display all the elements.

Figure 67: Second algebraic loop display in 04_ModualModel demo

This display is due to the fact that, reworking the model, the chassis submodel no longer be in an algebraic loop once both the 1st and 2nd loops have be broken. This is a limitation of nested algebraic loops: common elements of multiple loops may only be printed once, in the loop of upper index.