Robust Control Toolbox™

Specify uncertain state space models or convert LTI model to uncertain state space model

Syntax

• usys = uss(a,b,c,d) 
  usys = uss(a,b,c,d,Ts) 
  usys = uss(d) 
  usys = uss(a,b,c,d,Property,Value,...) 
  usys = uss(a,b,c,d,Ts,Property,Value,...) 
  usys = uss(sys) 
  

Description

uss creates uncertain state-space models (uss objects) or to convert LTI models to the uss class.

usys = uss(a,b,c,d) creates a continuous-time uncertain state-space object. The matrices a, b, c and d can be umat and/or double and/or uncertain atoms. These are the 4 matrices associated with the linear differential equation model to describe the system.

usys = uss(a,b,c,d,Ts) creates a discrete-time uncertain state-space object with sampling time Ts.

usys = uss(d) specifies a static gain matrix and is equivalent to usys = uss([],[],[],d).

Any of these syntaxes can be followed by property name/property value pairs.

usys = uss(a,b,c,d,'P1',V1,'P2',V2,...) set the properties P1, P2, ... to the values V1, V2, ...

usys = uss(sys) converts an arbitrary ss, tf or zpk model sys to an uncertain state space object without uncertainties. Both usys.NominalValue and simplify(usys,'class') are the same as ss(sys).

Example

You can first create two uncertain atoms and use them to create two uncertain matrices. These four matrices can be packed together to form a 1-output, 1-input, 2-state continuous-time uncertain state space system.

• p1 = ureal('p1',5,'Range',[2 6]); 
  p2 = ureal('p2',3,'Plusminus',0.4); 
  A = [-p1 0;p2 -p1]; 
  B = [0;p2]; 
  C = [1 1]; 
  usys = uss(A,B,C,0); 
  

In the second example, you can convert a not-uncertain tf model to an uncertain state-space model without uncertainties. You can verify the equality of the nominal value of the usys object and simplified representation to the original system.

• G = tf([1 2 3],[1 2 3 4]); 
  usys = uss(G) 
  USS: 3 States, 1 Output, 1 Input, Continuous System 
  isequal(usys.NominalValue,ss(G)) 
  ans = 
       1 
  isequal(simplify(usys,'class'),ss(G)) 
  ans = 
       1 
  

See Also
frd         Creates or converts to frequency response data model

ss          Creates or converts to state-space model

Provide feedback about this page

usample

usubs

© 1984-2008- The MathWorks, Inc.    -   Site Help   -   Patents   -   Trademarks   -   Privacy Policy   -   Preventing Piracy   -   RSS