Dear Aleksei,
Thank you for designing such a wonderful toolbox.It is very useful & interesting toolbox. I have one question about the optimization of fpid controller. With default values, first i tune all parameters & second time i tune parameters step by step( i.e first fix exponents & then fix gains).With this two methods i found that performance of system is different for each method. can you explain why this difference occurs ?
The t.f of plant used is 1/(s+1)^4 .
You are effectively bounding the parameter search space by fixing some parameters. Obviously, you will arrive at different results, because some fractional-order controller parameters yielding particular control performance will not be accessible.
This reply was modified 10 years, 8 months ago by Aleksei.
The choice of min/max step size depends on the dynamics of the control system under study. In addition, the difference in the transient response with different step sizes may be related to the Simulink solver used. This is all I can say without further details about your simulation.
This reply was modified 10 years, 4 months ago by Aleksei.