What is the purpose of Gmin and Gmax value in Hinfinty controller

ncont = 1;

nmeas = 2;

K = ss(zeros(ncont,nmeas,3));

gamma = zeros(3,1);

for i=1:3

i

[K(:,:,i),~,gamma(i)] = hinfsyn(qcaric(:,:,i),nmeas,ncont,'GMAX',inf,'GMIN',5,'METHOD','lmi','DISPLAY','on');

end

gamma;

for this code from active suspension control eventhough i am using Gmin as 5, I am getting these values of gamma =

0.9402

0.6774

1.0306

Answer 1

[Aquatris]

From the function page you can find the information you need. I am pasting it here for convenience.

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Performance range for search, specified as a vector of the form [gmin,gmax]. The hinfsyn command tests only performance levels within that range. It returns a controller with performance:

gamma ≤ gmin, when gmin is achievable

gmin < gamma < gmax, when gmax is achievable and but gmin is not

gamma = Inf when gmax is not achievable. In this case, hinfsyn returns [] for K and CL.

If you know a range of feasible performance levels, specifying this range can speed up computation by reducing the number of iterations performed by hinfsyn to test different performance levels.

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Basically it is not a strict constraint that the controller will results in gamma>= gmin. It is more of a suggestion for the algorithm to speed things up.

[Ayush Mittal]

Thank you for your response.

As stated above that It returns a controller with performance: gamma ≤ gmin, when gmin is achievable. So, is it accurate to say that if it will always give the same value of gamma irrespective of gmin as long as this condition is satisfied.

For example:

gamma= 0.9467

gmin= 1

so now if I increase the value of gmin (e.g. 2,5,10,100), will I still get the same gamma value for all these values of gmin?