Compare data at consecutive timesteps during runtime in Simulink

Hi all,

I'm trying to create a parachute model system for a rocket that will deploy when the altitude begins to decrease i.e. altitude at timestep n < altitude at timestep n-1.

I'm not entirely sure what the best way is to do this. I've played around with setting the altitude as a parameter of a masked subsystem but this didn't really work and made the simulation run significantly slower. Is there a fast way to extract a previous value of a logged signal?

Thanks!

Answer 1

[Fangjun Jiang]

Use a Unit Delay block, the input is altitude, the output is the "previous value" of the altitude.