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add parameters to PID controllers (#336)
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* add parameters to PID controllers

* workaround for scoping issue

* remove a_end parameter

* test: fix depwarn

* format

---------

Co-authored-by: Aayush Sabharwal <[email protected]>
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@baggepinnen @AayushSabharwal
baggepinnen and AayushSabharwal authored Oct 16, 2024
1 parent 37b5157 commit fc6c413
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Showing 4 changed files with 52 additions and 30 deletions.
68 changes: 45 additions & 23 deletions src/Blocks/continuous.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -258,13 +258,21 @@ See also [`LimPID`](@ref)
with_D = !isequal(Td, false)
@named err_input = RealInput() # control error
@named ctr_output = RealOutput() # control signal
!isequal(Ti, false) &&
(Ti ≥ 0 || throw(ArgumentError("Ti out of bounds, got $(Ti) but expected Ti ≥ 0")))
!isequal(Td, false) &&
(Td ≥ 0 || throw(ArgumentError("Td out of bounds, got $(Td) but expected Td ≥ 0")))
Nd > 0 || throw(ArgumentError("Nd out of bounds, got $(Nd) but expected Nd > 0"))
@symcheck Ti ≥ 0 ||
throw(ArgumentError("Ti out of bounds, got $(Ti) but expected Ti ≥ 0"))
@symcheck Td ≥ 0 ||
throw(ArgumentError("Td out of bounds, got $(Td) but expected Td ≥ 0"))
@symcheck Nd > 0 ||
throw(ArgumentError("Nd out of bounds, got $(Nd) but expected Nd > 0"))

pars = @parameters begin
k = k, [description = "Proportional gain"]
Ti = Ti, [description = "Integrator time constant"]
Td = Td, [description = "Derivative time constant"]
Nd = Nd, [description = "Derivative limit"]
end

@named gainPID = Gain(k)
@named gainPID = Gain(; k)
@named addPID = Add3()
if with_I
@named int = Integrator(k = 1 / Ti, x = int__x)
Expand Down Expand Up @@ -304,7 +312,7 @@ See also [`LimPID`](@ref)
else
push!(eqs, connect(Dzero.output, addPID.input3))
end
ODESystem(eqs, t, [], []; name = name, systems = sys)
ODESystem(eqs, t, [], pars; name = name, systems = sys)
end

"""
Expand Down Expand Up @@ -334,15 +342,22 @@ The simplified expression above is given without the anti-windup protection.
throw(ArgumentError("Time constant `Ta` has to be strictly positive"))
@symcheck T > 0 || throw(ArgumentError("Time constant `T` has to be strictly positive"))
@symcheck u_max ≥ u_min || throw(ArgumentError("u_min must be smaller than u_max"))
pars = @parameters begin
k = k, [description = "Proportional gain"]
T = T, [description = "Integrator time constant"]
Ta = Ta, [description = "Tracking time constant"]
u_max = u_max, [description = "Upper saturation limit"]
u_min = u_min, [description = "Lower saturation limit"]
end
@named err_input = RealInput() # control error
@named ctr_output = RealOutput() # control signal
@named gainPI = Gain(k)
@named gainPI = Gain(; k)
@named addPI = Add()
@named addTrack = Add()
@named int = Integrator(k = 1 / T, x = int__x)
@named limiter = Limiter(y_max = u_max, y_min = u_min)
@named addSat = Add(k1 = 1, k2 = -1)
@named gainTrack = Gain(1 / Ta)
@named gainTrack = Gain(k = 1 / Ta)
sys = [err_input, ctr_output, gainPI, addPI, int, addTrack, limiter, addSat, gainTrack]
eqs = [
connect(err_input, addPI.input1),
Expand All @@ -357,7 +372,7 @@ The simplified expression above is given without the anti-windup protection.
connect(addTrack.output, int.input),
connect(int.output, addPI.input2)
]
ODESystem(eqs, t, [], []; name = name, systems = sys)
ODESystem(eqs, t, [], pars; name = name, systems = sys)
end

"""
Expand Down Expand Up @@ -408,18 +423,25 @@ where the transfer function for the derivative includes additional filtering, se
Ti = k / Ti
Td = Td / k
end
0 ≤ wp ≤ 1 ||
throw(ArgumentError("wp out of bounds, got $(wp) but expected wp ∈ [0, 1]"))
0 ≤ wd ≤ 1 ||
throw(ArgumentError("wd out of bounds, got $(wd) but expected wd ∈ [0, 1]"))
!isequal(Ti, false) &&
(Ti ≥ 0 || throw(ArgumentError("Ti out of bounds, got $(Ti) but expected Ti ≥ 0")))
!isequal(Td, false) &&
(Td ≥ 0 || throw(ArgumentError("Td out of bounds, got $(Td) but expected Td ≥ 0")))
@symcheck Ti ≥ 0 ||
throw(ArgumentError("Ti out of bounds, got $(Ti) but expected Ti ≥ 0"))
@symcheck Td ≥ 0 ||
throw(ArgumentError("Td out of bounds, got $(Td) but expected Td ≥ 0"))
@symcheck u_max ≥ u_min || throw(ArgumentError("u_min must be smaller than u_max"))
@symcheck Nd > 0 ||
throw(ArgumentError("Nd out of bounds, got $(Nd) but expected Nd > 0"))

pars = @parameters begin
k = k, [description = "Proportional gain"]
Ti = Ti, [description = "Integrator time constant"]
Td = Td, [description = "Derivative time constant"]
wp = wp, [description = "Set-point weighting in the proportional part"]
wd = wd, [description = "Set-point weighting in the derivative part"]
Ni = Ni, [description = "Anti-windup tracking gain"]
Nd = Nd, [description = "Derivative limit"]
u_max = u_max, [description = "Upper saturation limit"]
u_min = u_min, [description = "Lower saturation limit"]
end
@named reference = RealInput()
@named measurement = RealInput()
@named ctr_output = RealOutput() # control signal
Expand All @@ -431,7 +453,7 @@ where the transfer function for the derivative includes additional filtering, se
if with_AWM
@named addI = Add3(k1 = 1, k2 = -1, k3 = 1)
@named addSat = Add(k1 = 1, k2 = -1)
@named gainTrack = Gain(1 / (k * Ni))
@named gainTrack = Gain(k = 1 / (k * Ni))
else
@named addI = Add(k1 = 1, k2 = -1)
end
Expand Down Expand Up @@ -492,7 +514,7 @@ where the transfer function for the derivative includes additional filtering, se
push!(eqs, connect(Dzero.output, addPID.input2))
end

ODESystem(eqs, t, [], []; name = name, systems = sys)
ODESystem(eqs, t, [], pars; name = name, systems = sys)
end

"""
Expand Down Expand Up @@ -611,13 +633,13 @@ See also [`StateSpace`](@ref) which handles MIMO systems, as well as [ControlSys
description = "Denominator coefficients of transfer function (e.g., `s² + 2ωs + ω^2` is specified as [1, 2ω, ω^2])"
]
bb[1:(nbb + nb)] = [zeros(nbb); b]
d = bb[1] / a[1], [description = "Direct feedthrough gain"]
end
d = bb[1] / a[1]# , [description = "Direct feedthrough gain"]

a = collect(a)
@parameters a_end = ifelse(a[end] > 100 * symbolic_eps(sqrt(a' * a)), a[end], 1.0)
a_end = ifelse(a[end] > 100 * symbolic_eps(sqrt(a' * a)), a[end], 1.0)

pars = [collect(b); a; collect(bb); d; a_end]
pars = [collect(b); a; collect(bb)]
@variables begin
x(t)[1:nx] = zeros(nx),
[description = "State of transfer function on controller canonical form"]
Expand Down
2 changes: 1 addition & 1 deletion src/Blocks/nonlinear.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,7 @@ Limit the range of a signal.
@component function Limiter(; name, y_max, y_min = y_max > 0 ? -y_max : -Inf)
@symcheck y_max ≥ y_min || throw(ArgumentError("`y_min` must be smaller than `y_max`"))
m = (y_max + y_min) / 2
@named siso = SISO(u_start = m, y_start = m) # Default signals to center of saturation to minimize risk of saturation while linearizing etc.
siso = SISO(u_start = m, y_start = m, name = :siso) # Default signals to center of saturation to minimize risk of saturation while linearizing etc.
@unpack u, y = siso
pars = @parameters y_max=y_max [description = "Maximum allowed output of Limiter $name"] y_min=y_min [
description = "Minimum allowed output of Limiter $name"
Expand Down
10 changes: 5 additions & 5 deletions test/Blocks/continuous.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -430,7 +430,7 @@ end
@named pt1 = TransferFunction(b = [1.2], a = [3.14, 1])
@named iosys = ODESystem(connect(c.output, pt1.input), t, systems = [pt1, c])
sys = structural_simplify(iosys)
prob = ODEProblem(sys, Pair[pt1.a_end => 1], (0.0, 100.0))
prob = ODEProblem(sys, Pair[], (0.0, 100.0))
sol = solve(prob, Rodas4())
@test sol.retcode == Success
@test sol[pt1.output.u]≈pt1_func.(sol.t, 1.2, 3.14) atol=1e-3
Expand All @@ -440,7 +440,7 @@ end
@named pt1 = TransferFunction(b = [1.2], a = [3.14, 0])
@named iosys = ODESystem(connect(c.output, pt1.input), t, systems = [pt1, c])
sys = structural_simplify(iosys)
prob = ODEProblem(sys, Pair[pt1.a_end => 1], (0.0, 100.0))
prob = ODEProblem(sys, Pair[], (0.0, 100.0))
sol = solve(prob, Rodas4())
@test sol.retcode == Success
@test sol[pt1.output.u] ≈ sol.t .* (1.2 / 3.14)
Expand All @@ -464,7 +464,7 @@ end
@named pt1 = TransferFunction(b = [w^2], a = [1, 2d * w, w^2])
@named iosys = ODESystem(connect(c.output, pt1.input), t, systems = [pt1, c])
sys = structural_simplify(iosys)
prob = ODEProblem(sys, Pair[pt1.a_end => 1], (0.0, 100.0))
prob = ODEProblem(sys, Pair[], (0.0, 100.0))
sol = solve(prob, Rodas4())
@test sol.retcode == Success
@test sol[pt1.output.u]≈pt2_func.(sol.t, k, w, d) atol=1e-3
Expand All @@ -474,7 +474,7 @@ end
@named pt1 = TransferFunction(b = [1, 0], a = [1, 1])
@named iosys = ODESystem(connect(c.output, pt1.input), t, systems = [pt1, c])
sys = structural_simplify(iosys)
prob = ODEProblem(sys, Pair[pt1.a_end => 1], (0.0, 100.0))
prob = ODEProblem(sys, Pair[], (0.0, 100.0))
sol = solve(prob, Rodas4())
@test sol.retcode == Success
@test sol[pt1.output.u]≈1 .- pt1_func.(sol.t, 1, 1) atol=1e-3
Expand All @@ -484,7 +484,7 @@ end
@named pt1 = TransferFunction(b = [2.7], a = [pi])
@named iosys = ODESystem(connect(c.output, pt1.input), t, systems = [pt1, c])
sys = structural_simplify(iosys)
prob = ODEProblem(sys, Pair[pt1.a_end => 1], (0.0, 100.0))
prob = ODEProblem(sys, Pair[], (0.0, 100.0))
sol = solve(prob, Rodas4())
@test sol.retcode == Success
@test all(==(2.7 / pi), sol[pt1.output.u])
Expand Down
2 changes: 1 addition & 1 deletion test/Mechanical/translational_modelica.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -105,5 +105,5 @@ end
prob = ODEProblem(sys, [], (0, 2pi))
sol = solve(prob, Rodas4())
tv = 0:0.1:(2pi)
@test sol(tv, idxs = sys.mass.s)≈@.(2sin(2pi * tv * 3)) atol=1e-2
@test sol(tv, idxs = sys.mass.s).u≈@.(2sin(2pi * tv * 3)) atol=1e-2
end

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