Is there a way to reset after a given time the initial condition of an integrator block in simulink?

I have to simulate the attitude determination of a satellite integrating the measurements of the angular velocities I got from a gyroscope. As initial condition I can use the values i got from other sensors to start the integration. by comparison with the exact attitude i notice that the integrated one from the measurement diverges (of course) as time goes. i was suggested to reset the integral after some time by putting a new initial condition but i haven't found a way to do it so my question is: how can i change the initial value of the integration after some time to reduce the errors introduced by the integration?

thanks to whoever can clarify me this point

Answer 1

[Paul]

If you haven't already, check out section Resetting the State on the Integrator block doc page.

[Luca Caffiero]

I've already did that but all I've understood is that i can reset the initial value as the output reaches a certain value while i want to give a new initial value after an assigned time has passed

[Paul]

Here's an example with the integrator external reset set to rising and reset to occur at t == 5.

[Luca Caffiero]

thanks for your answer, much appreciated! but my problem is a little different, i will refer to your example to be more clear. let's say that after t=5 i want to change the initial condition so that in the first 5 seconds i have one, then i change it to something else. is that feasible?

this is in the specific my case:

the yellow line is the quaternion i get integrating the real angular velocity, in violet the one obtained integrating the measured angular velocity. as time passes they diverge, so i want that every 1000 seconds the integration of the measured velocity take a new initial condition to ''re-align'' the two plots. this initial condition has to be taken from the exact quaternion.

it's basically a navigation problem in which periodically it's needed to retrieve the exact position since by integrating the speed errors accumulate over time.

[Paul]

The external initial condition input to the the integrator can be the output from another block. It sounds like you want to use the true quaternion as the input to the initial condition port of the integrator block in question. Then this integrator will initialize to the true quaternion at t=0 and reset to the true quaternion based on the input to to the external reset port.

[Luca Caffiero]

thanks man you saved my day! very much appreciated i wish you well!