Convert discrete to continuous using delays

Specific Domains Modelling & Simulations
10

Here’s the corresponding one for statespace systems

using LinearAlgebra
function d2dc(sys::AbstractStateSpace{<:Discrete})
    T = sys.Ts
    A,B,C,D = ssdata(sys)
    z = delay(-T)
    LR = append([z for _ in 1:sys.nx]...) - ss(A + I)
    C * feedback(I(sys.nx), LR)*B + D
end

sys = ssrand(2, 3, 2, Ts = 1) # A random discrete-time MIMO system
sysc = d2dc(sys)

bodeplot(sys, w, lab="Discrete SS")
bodeplot!(sysc, w, lab="Continuous SS with delays", l=:dash, size=(800, 800))

image
image960×963 48.9 KB

Cool, thanks for the detail! I was considering asking what your application was that required such precision in the frequency response close to the Nyquist frequency.

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