Hinfgs Question Control Input Number

When I am using hinfgs I have to tell it the number of measurements and control inputs.

I have my system defined with a B matrix that includes two submatrices, one for the control inputs and one for the exogenous inputs.

I am using a command called 'sconnect' to define the interconnnected system before passing it to hinfgs. My question is, the output of sconnect tells me that I have 12 measurements and 24 control inputs. I have 12 measurements and 6 control inputs. However, I do have a total of 24 inputs between exogenous inputs and control inputs.

Is this going to be an issue? It seems that sconnect is just returning whatever number of columns are in my big B matrix not taking into account that not all of those are control inputs. Should I just manually overright it with the correct number (6)?

Answer 1

[SOUMNATH PAUL]

Hi @Tristan,

Yes, this can be an issue for the design of your H-infinity controller using "hinfsyn". The "hinfsyn" function requires the correct number of control inputs to design the controller properly. If "sconnect" is returning a system with all inputs (control plus exogenous) combined as control inputs, this will mislead "hinfsyn" into considering all inputs as controllable, which is not the case.

You should manually specify the correct number of control inputs (which is 6 in your case) when calling "hinfsyn". You do not need to "overwrite" the number per se, but rather ensure that when you construct the system to be passed into "hinfsyn", it correctly reflects the number of control inputs and measurements.

Hope it helps!

Regards,

Soumnath