270 Chapter 6. Function Reference
pk-
zw
y
u
The variablesncon and nmeas are used to sp ecify the dimensions of uand yin the above
diagram (ncon = dim(u)andnmeas = dim(y)). The objective is to design a stabilizing
controller, k, whichminimizes the H2norm of the closed lo op system betweenwand z.
pis a state-space system, which can be partitioned with respect to [z;y]and[w;u]in
the following way.
p=
ab1b2
c1d11 d12
c2d21 d22
.
The following assumptions must hold:
1. (a,b2,c
2) is stabilizable and detectable
2. d12 and d21 have full rank
3. d11 =0
4. The matrix [a−jωI,b2;c1,d
12] has full column rank for all ω
5. The matrix [a−jωI,b1;c2,d
21] has full row rank for all ω
In theory the Riccati equations should always have a solution. However, Hamiltonian
eigenvalues whichar e close to the imaginary axis will give problems. epr specifies a
tolerance for how close the calculated eigenvalues can be to the jω axis.