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Improvement on Bode plot phase #312

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Improvement on Bode plot phase #312

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b799c51
Fix bode plot always negative phase
tallakt Sep 2, 2020
55eca81
Algorithm to estimate initial phase angle for bode
tallakt Sep 3, 2020
feecfbc
Allow unwrap! to start from an initial value
tallakt Sep 3, 2020
066bce8
Optimize bode function
tallakt Sep 3, 2020
3281062
Fix a bug in unwrap!
tallakt Sep 3, 2020
579acf4
Optimize bode function by using function `count`
tallakt Sep 3, 2020
22a369d
Add init=... for bodeplot phase with unwrap
Sep 3, 2020
d9075a1
Make bode phase estimate thresholds configurable
Sep 3, 2020
dab68bc
Bode plot frequency disabled for DelayLtiSystem
Sep 4, 2020
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12 changes: 11 additions & 1 deletion src/freqresp.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -104,7 +104,17 @@ at frequencies `w`
`mag` and `phase` has size `(length(w), ny, nu)`"""
function bode(sys::LTISystem, w::AbstractVector)
resp = freqresp(sys, w)
return abs.(resp), rad2deg.(unwrap!(angle.(resp),1)), w
# use the number of integrators in the system to estimate initial phase
count_unit_circle = x -> count(abs.(abs.(x) .- 1.0) .< 1e-5)
count_zeros = x -> count(abs.(x) .< 1e-8)

phase0 = if sys.Ts == 0.0
pi/2 * (count_zeros(zpk(sys).matrix[1].z) - count_zeros(zpk(sys).matrix[1].p))
else
pi/2 * (count_unit_circle(zpk(sys).matrix[1].z) - count_unit_circle(zpk(sys).matrix[1].p))
end
phase = rad2deg.(unwrap!(vcat(phase0, angle.(resp)),1))[2:end]
return abs.(resp), phase, w
end
bode(sys::LTISystem) = bode(sys, _default_freq_vector(sys, Val{:bode}()))

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