Control System Tuner always selects maximum value
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Hey,
I am new to the Matlab Control System Toolbox and want to try out the Control System Tuner but I am facing a weird problem.
This is my control loop:
And I want to tune the PI controller to achieve a stable response. So I have specified the following Step Tracking Goal:
However, the Control System Tuner just gives me the maximum possible gain:
Does someone of you has an idea if I have to adjust the settings somehow or what else could be the reason for this behaviour?
Thanks
回答（1 个）
Hi @Cedric
The algorithm in Control System Tuner will find the best combination of PI gains that produces the smallest steady-state error.
In your case, by selecting the maximum allowable gain for 
, the smallest steady-state error is achieved.
, the smallest steady-state error is achieved. However, if a Proportional Controller is placed at the feedback path, and set 
, the desired response 
is achieved PERFECTLY!
, the desired response is achieved PERFECTLY!Gp = tf(1, [1 -1])
Gc = pid(1000);
Gcl = feedback(Gc*Gp, 1)
sse = abs(dcgain(Gcl) - 1)
Alternative solution:
2 个评论
Cedric
2024-7-4
Thank you for your response.
I am not searching for the solution to this specific control loop but more asking how i can make the CST to find the solution that fits best to the desired response 
. From my point of view this would be 
.
. From my point of view this would be .Hi @Cedric
Inside the Control System Tuner, there are rules that prevent it from using an unstable zero to cancel out an unstable pole.
Gp = tf(1, [1 -1])
Gc = pid(1, -1)
Gcl = feedback(Gc*Gp, 1)
ToF = isstable(Gcl) % 0 means False
step(Gcl, 40), grid on
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