Why can't I tune my controllers in Simulink Control Design?

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I am trying to tune controllers in my model using either Control System Tuner or the PID Tuner App. However, I keep getting error messages such as:
"Linearization resulted in a system that cannot be tuned, you may try a different operating point(s)."
"Plant cannot be linearized. Use the Plant menu to create or select a new plant"
How do I tune my controllers in the model?

Accepted Answer

MathWorks Support Team
MathWorks Support Team on 20 Jun 2018
In order for Simulink to perform its tuning capabilities, it must be able to linearize the plant model. Simulink performs linearization using a block-by-block approach, then combines the individual block linearizations to product the overall system linearization. The linearization of each block can use one of two different methods:
1) Analytical linearization: obtain the Jacobian from the block
2) Numerical perturbation: perturb the block by a small amount and compute a linear model based on the response to these perturbations
Strong discontinuities in a block (such as those generated by PWM signals) can cause poor linearization results, e.g. linearizing to zero or an infinite gain. Therefore, such blocks require special handling.
For more on this, see the following page, which describes common problematic blocks and potential solutions for linearizing them:
Refer to the following page when troubleshooting linearization results in general, which provides a number of useful resources and approaches for obtaining better linearization results:
To handle poor linearization results, you can specify a custom linearization for a block if it is known. This can be down using either of these two approaches:
An alternative approach is to use the System Identification Toolbox to identify a linear system for the block. An example of how to do that can be found here:

More Answers (2)

Tony Castillo
Tony Castillo on 14 Feb 2019
Hi all;
Indeed I am sure I am experiencing the same issue you already have overpassed, that cheer me up to ask you, could you please tell me how solve it?, , that cheer me up to ask you, could you please tell me how solve it?, because I have not been able to solve it by myself, in spite of, I was seeking some insights on the documentation you previously shared in here, I do need more details in order to overcome my issue, and my problem is not being able to tune up my PID controller by the impossibility of SIMULINK to have linearize my plant. Error Message

lixia on 8 Mar 2020
I am wondering if your problem has been solved.If so,could you please share your solution?


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