Compensator design with sisotool

Dear all,

I am having an issue when trying to design a "compensator" C using sisotool. Don't know if this is a bug in sisotool or a lack of understanding from my side. Let me explain, I will try to be concise and clear.

I have a SISO feedback system that corresponds to the "Confiuration 2" in sisotool, i.e. the controller C is in the feedback path (next to the H block, not the G block). I want to tune this C in order to have a good closed-loop transfer function (from input r to output y). I initialize my matrices and use the command:

sisotool(G,C,H,F);

with C set to 1. sisotool opens, I select configuration 2, open the looptransfer_C editor and plot the closed-loop r to y IO transfer function. I expect that when I add poles and zeros to the looptransfer_C (i.e. to C), the closed-loop transfer function should be changing as it is r/y = FG/(1+CGH).

However, the r to y transfer function does not change at all when I edit C... Note that if I use configuration 1 (the default one with C in the open-loop path, next to the G block), the process I described works very well. I can see the r/y tranfer function changing while I tune the C block... But it does not works in configuration 2, which is the one I need.

Is anyone out there familiar with sistool and can help me with that ? I would really appreciate.

Many thanks,

Anthony.

[Siddharth Jawahar]

Hi Anthony,

Could you share reproduction steps with some images? I am not able to reproduce it on my end.

Sid