How can I make my simulation stop when my graph hits 0? (Simulink)

I looked everywhere and I just can't figure out how to do this. I have graph that is an upside down porabola that starts from 0. I want the simulation to stop when it hits 0 the second time. I'm not sure what blocks I should use to achieve this. I tried solving it with an if block and a stop block but wasn't able to get it to work. Any help would be appreciated. Thanks

Answer 1

[Andy Bartlett]

You can build a solution using the Stop Block.

You'll need to build the logic that feeds the Stop Block input using

relational operators or "detect blocks"

and use blocks with state to keep track of the counts.

The state needs can be managed with unit delays and switch blocks

or you can use the discrete integrator block configured to Accumulator mode (which does not multiply inputs by sample time).