Hi ; i try to implement a matlab example in the link http://www​.mathworks​.com/help/​robust/gs/​active-sus​pension-co​ntrol-desi​gn.html but i got a message error. so kindly can any one explain why i got this error since i just implement the publishe code

mb = 300;    % kg
mw = 60;     % kg
bs = 1000;   % N/m/s
ks = 16000 ; % N/m
kt = 190000; % N/m
A = [ 0 1 0 0; ...
    [-ks -bs ks bs]/mb ; ...
      0 0 0 1; ...
      [ks bs -ks-kt -bs]/mw];
B = [0 0; 0 10000/mb ; 0 0; [kt -10000]/mw];
C = [1 0 0 0; 1 0 -1 0; A(2,:)];
D = [0 0; 0 0; B(2,:)];

qcar = ss(A,B,C,D);

ActNom = tf(1,[1/60 1]);
Wunc = makeweight(0.40,15,3);
unc = ultidyn('unc',[1 1],'SampleStateDimension',5);
Act = ActNom*(1 + Wunc*unc);
Act.InputName = 'u';
Act.OutputName = 'fs';
bodeplot(Act,'b',Act.NominalValue,'r+',logspace(-1,3,120))
title('Nominal and 20 random actuator models')

??? Error using ==> gsref.set at 36
Property SampleStateDimension is not gettable.

Error in ==> gsref.set at 36
                  error(['Property ' varargin{2*i-1} ' is
                  not gettable.']);

Error in ==> ultidyn.ultidyn at 81
      out = set(out,varargin{2*(ii-1)+1},varargin{2*ii});

Error in ==> Untitled at 18
unc = ultidyn('unc',[1 1],'SampleStateDimension',5);

Answer 1

[Walter Roberson]

The link you provided no longer exists in R2016a . The replacement appears to be http://www.mathworks.com/help/releases/R2016a/robust/examples/robust-control-of-an-active-suspension.html

I note that the R2016a documentation for ultidyn gives the property name as SampleSpaceDimension, the same as the code you posted, but that the current version of the example uses 'SampleStateDim' .

I suggest you try with the code posted in the R2016a example -- though if that fails then it might be a bug in the version you have that hypothetically might have been fixed by R2016a.

[Muna Shehan]

Thanks for your response. The version i used is 2011a, so how i can fit the code posted with my current version (2011a).

[Walter Roberson]

It turns out that 'SampleSpaceDimension' was a change as of R2015b, and that previous to that it was 'SampleStateDim', so change to that in your code and you might be able to get further.