MPC designer error: Designing state estimator

I have an XT28 model

I add a MPC controller (MPC toolbox) to one of the legs. Sometimes when I run the XT28 with a MPC controller I get an MPC designer error that says the following:

"Problems encountered when designing the default state estimator (Kalman filter) used by MPC.

Controller cannot be designed in the app. Use commands to investigate the problem.

For example, increase the sample when there is a large time delay in the plant model and make sure all the unstable modes are observable"

I use the matlab version R2019b.

I have tried to search for the error but not been able to find anything. I dont understand what is causing the error. Do anyone know?

Answer 1

[Ahmed Elgohary]

Well, try to change the smaple time of your MPC Controller, it seems that your model has a huge delay and is not comptiable with the MPC sample time. So try to start by 50 or 100 as your initial smaple time of your MPC. But most probably your controller will not work as the step time is so large, so try to recheck your model or make it run more faster and try again.