Algebraic loop error - Simulink

Hi, I was wondering if anyone could help.

Answer 1

[Paul]

Hi John,

The model equations as implemented are:

(1) actual_height = new_height

(2) new_height = displacement + actual_height

Or

(3) actual_height = dispslacement + actual_height

which is the algebraic loop.

Is that what the equations should be?

[John]

I see the error now. I think I need to add a time delay in the first equation. The ‘new height’ should be actual height but only for the next time step.

Do you think that adding a ‘delay one step’ block, in between the plant ‘new height’ output and ‘actual height’ input, would achieve this?

[Paul]

Adding a delay somewhere between 'actual height' and 'new height' will remove the algebraic loop. But it's probabably an indication that something isn't being modeled correctly in the first place.