diff --git a/README.md b/README.md
index 408e54263ef7828f3ab61e1d3f50ac58f4232eac..2bae4d9c6249e9fa8444bdad9804708d2d60fce9 100644
--- a/README.md
+++ b/README.md
@@ -66,18 +66,21 @@ end
Often one finds the need to implement a stateful controller, i.e., a function
-that has a memory or state. To this end, the function [`sysfilter`](@ref) is
-provided. This function is used to implement control loops where a signal is
-filtered through a dynamical system, i.e., `U(z) = C(z)E(z)`.
+that has a memory or state. To this end, the type [`SysFilter`](@ref) is
+provided. This type is used to implement control loops where a signal is
+filtered through a dynamical system, i.e., `U(z) = G1(z)E(z)`.
Usage is demonstrated below, which is a simplified implementation of the block
diagram above (transfer function- and signal names corresponds to the figure).
+First two `SysFilter` objects are created, these objects can now be used as
+functions of an input, and return the filtered output. The `SysFilter` type takes
+care of updating remembering the state of the system when called.
```julia
-stateG1 = init_sysfilter(G1)
-stateG4 = init_sysfilter(G4)
+G1f = SysFilter(G1)
+G4f = SysFilter(G4)
function control(i)
- rf = sysfilter!(stateG4, G4, r)
+ rf = G4f(r)
e = rf-y
- u = sysfilter!(stateG1, G1, e)
+ u = G1f(e)
end
```
`G1` and `G4` must here be represented by [`StateSpace`](http://juliacontrol.github.io/ControlSystems.jl/latest/lib/constructors/#ControlSystems.ss) types from [`ControlSystems.jl`](https://github.com/JuliaControl/ControlSystems.jl).
@@ -93,19 +96,18 @@ This is very easy, just get a discrete time `StateSpace` model of your process
You now have to implement the methods `control` and `measure` for your simulated type.
The implementation for `BeamSimulator` is shown below
```julia
-function control(p::BeamSimulator, u)
- sysfilter!(p.state, p.sys, u)
-end
-measure(P) = vecdot(p.sys.C,p.state)
+control(p::BeamSimulator, u) = p.Gf(u)
+measure(P) = vecdot(p.Gf.sys.C, p.Gf.state)
```
The `control` method accepts a control signal (`u`) and propagates the system state
-(`p.state`) forward using the statespace model (`p.sys`) of the beam. The function
-[`sysfilter!`](@ref) is familiar from the "Control" section above. What it does
-is essentially
+(`p.Gf.state`) forward using the statespace model (`p.Gf.sys`) of the beam. The object
+[`Gf::SysFilter`](@ref) is familiar from the "Control" section above. What it does
+is essentially (simplified)
```julia
-function sysfilter!(state, sys, input)
- state .= sys.A*state + sys.B*input
- output = sys.C*state + sys.D*input
+function Gf(input)
+ sys = Gf.sys
+ Gf.state .= sys.A*Gf.state + sys.B*input
+ output = sys.C*Gf.state + sys.D*input
end
```
hence, it just performs one iteration of
@@ -125,19 +127,20 @@ It should now be obvious which fields are required in the `BeamSimulator` type.
It must know which sample time it has been discretized with, as well as its
discrete-time system model. It must also remember the current state of the system.
This is not needed in a physical process since it kind of remembers its own state.
+The system model and its state is conveniently covered by the type [`SysFilter`](@ref),
+which handles filtering of a signal through an LTI system.
The full type specification for `BeamSimulator` is given below
```julia
struct BeamSimulator <: SimulatedProcess
h::Float64
- state::Vector{Float64} # states defined by the file define_beam_system
- sys::StateSpace
- BeamSimulator() = new(0.01, init_sysfilter(beam_system), c2d(beam_system, 0.01)[1])
- BeamSimulator(h::Real) = new(Float64(h), init_sysfilter(beam_system), c2d(beam_system, h)[1])
+ Gf::SysFilter
+ BeamSimulator() = new(0.01, SysFilter(beam_system, 0.01))
+ BeamSimulator(h::Real) = new(Float64(h), SysFilter(beam_system, h))
end
```
It contains three fields and two inner constructors. The constructors initializes
-the system state by calling `init_sysfilter`. The variable `beam_system` is already
-defined outside the type specification.
+the system filter by creating a [`SysFilter`](@ref).
+The variable `beam_system` is already defined outside the type specification.
One of the constructors provides a default value for the sample time, in case
the user is unsure about a reasonable value.
diff --git a/src/LabProcesses.jl b/src/LabProcesses.jl
index a2277f380f08e592d5d3ac9bf85e4d9daa8490f0..c77a735b6813fbe9bfc81b93d6a2f81f2e101dd5 100644
--- a/src/LabProcesses.jl
+++ b/src/LabProcesses.jl
@@ -4,11 +4,12 @@ module LabProcesses
using ControlSystems
+include("utilities.jl")
+
include("interface.jl")
include("interface_documentation.jl")
include("interface_implementations/ballandbeam.jl")
-include("utilities.jl")
include("reference_generators.jl")
include("controllers.jl")
diff --git a/src/controllers.jl b/src/controllers.jl
index 93a2102d950955cde68ee8128b2f5ecb1f0414f6..f0ef21e600431e4486121a4cd12bd37799808496 100644
--- a/src/controllers.jl
+++ b/src/controllers.jl
@@ -18,15 +18,15 @@ function run_control_2DOF(P::AbstractProcess,sysFB, sysFF=nothing; duration = 10
u = zeros(nu, length(0:h:duration))
r = zeros(ny, length(0:h:duration))
- stateFB = init_sysfilter(sysFB)
+ Gfb = SysFilter(sysFB)
if sysFF != nothing
- stateFF = init_sysfilter(sysFF)
+ Gff = SysFilter(sysFF)
end
function calc_control(i)
- rf = sysFF == nothing ? r[:,i] : sysfilter!(stateFF, sysFF, r[:,i])
+ rf = sysFF == nothing ? r[:,i] : Gff(r[:,i])
e = rf-y[:,i]
- ui = sysfilter!(stateFB, sysFB, e)
+ ui = Gfb(e)
ui + bias(P)
end
diff --git a/src/interface_implementations/ballandbeam.jl b/src/interface_implementations/ballandbeam.jl
index d83dd025762a1dac39e788243b739f8d2d1e551f..5681bc8e6a27d2a7ebc15787dcb448f43f4319c4 100644
--- a/src/interface_implementations/ballandbeam.jl
+++ b/src/interface_implementations/ballandbeam.jl
@@ -22,10 +22,9 @@ const beam_system, nice_beam_controller = define_beam_system()
# nice_beam_controller gives ϕₘ=56°, Aₘ=4, Mₛ = 1.6. Don't forget to discretize it before use
struct BeamSimulator <: SimulatedProcess
h::Float64
- state::Vector{Float64} # states defined by the file define_beam_system
- sys::StateSpace
- BeamSimulator() = new(0.01, init_sysfilter(beam_system), c2d(beam_system, 0.01)[1])
- BeamSimulator(h::Real) = new(Float64(h), init_sysfilter(beam_system), c2d(beam_system, h)[1])
+ s::SysFilter
+ BeamSimulator() = new(0.01, SysFilter(beam_system, 0.01))
+ BeamSimulator(h::Real) = new(Float64(h), SysFilter(beam_system, h))
end
struct BallAndBeam <: PhysicalProcess
@@ -36,9 +35,9 @@ BallAndBeam() = BallAndBeam(0.01, 0.0)
struct BallAndBeamSimulator <: SimulatedProcess
h::Float64
- state::Vector{Float64} # pos,vel,angle,ω
+ s::SysFilter
end
-BallAndBeamSimulator() = BallAndBeamSimulator(0.01, zeros(4))
+
const AbstractBeam = Union{Beam, BeamSimulator}
@@ -64,9 +63,8 @@ bias(p::BallAndBeamSimulator) = 0
control(p::AbstractBeamOrBallAndBeam, u) = ccall((:comedi_write, comedipath),Int32,
(Int32,Int32,Int32,Int32),0,1,1,num2io(u[1]+p.bias))
-function control(p::BeamSimulator, u)
- sysfilter!(p.state, p.sys, u)
-end
+control(p::BeamSimulator, u) = p.s(u)
+
control(p::BallAndBeamSimulator, u) = error("Not yet implemented")
measure(p::Beam) = io2num(ccall((:comedi_read,comedipath), Int32,
@@ -74,7 +72,7 @@ measure(p::Beam) = io2num(ccall((:comedi_read,comedipath), Int32,
measure(p::BallAndBeam) = [io2num(ccall((:comedi_read,comedipath), Int32,
(Int32,Int32,Int32), 0,0,i)) for i = 0:1]
-measure(p::BeamSimulator) = vecdot(p.sys.C,p.state)
+measure(p::BeamSimulator) = vecdot(p.s.sys.C,p.s.state)
measure(p::BallAndBeamSimulator) = error("Not yet implemented")
@@ -87,5 +85,5 @@ initialize(p::AbstractBeamOrBallAndBeam) = ccall((:comedi_start, comedipath),Int
finalize(p::AbstractBeamOrBallAndBeam) = (control(p,0);ccall((:comedi_stop, comedipath),Int32,(Int32,), 0))
initialize(p::BallAndBeamSimulator) = nothing
finalize(p::BallAndBeamSimulator) = nothing
-initialize(p::BeamSimulator) = p.state .*= 0
+initialize(p::BeamSimulator) = p.s.state .*= 0
finalize(p::BeamSimulator) = nothing
diff --git a/src/utilities.jl b/src/utilities.jl
index 3dc62305c91b4e9d14359c4d1931189e04c11a19..7e70ba4d9fd351ce1b714decf81173039ccfa667 100644
--- a/src/utilities.jl
+++ b/src/utilities.jl
@@ -1,4 +1,4 @@
-export @periodically, init_sysfilter, sysfilter!
+export @periodically, init_sysfilter, sysfilter!, SysFilter
"""
@periodically(h, body)
@@ -27,6 +27,36 @@ macro periodically(h, simulation, body)
end
end
+
+"""
+ Csf = SysFilter(sys_discrete::StateSpace)
+ Csf = SysFilter(sys_continuous::StateSpace, sampletime)
+ Csf = SysFilter(sys::StateSpace, state::AbstractVector)
+Returns an object used for filtering signals through LTI systems.
+Create a SysFilter object that can be used to implement control loops and simulators
+with LTI systems, i.e., `U(z) = C(z)E(z)`. To filter a signal `u` through the filter,
+call like `y = Csf(u)`. Calculates the filtered output `y` in `y = Cx+Du, x'=Ax+Bu`
+"""
+struct SysFilter
+ sys::StateSpace
+ state::Vector{Float64}
+ function SysFilter(sys::StateSpace, state::AbstractVector)
+ @assert !ControlSystems.iscontinuous(sys) "Can not filter using continuous time model."
+ @assert length(state) == sys.nx "length(state) != sys.nx"
+ new(sys, state)
+ end
+ function SysFilter(sys::StateSpace)
+ @assert !ControlSystems.iscontinuous(sys) "Can not filter using continuous time model. Supply sample time."
+ new(sys, init_sysfilter(sys))
+ end
+ function SysFilter(sys::StateSpace, h::Real)
+ @assert ControlSystems.iscontinuous(sys) "Sample time supplied byt system model is already in discrete time."
+ sysd = c2d(sys, h)[1]
+ new(sysd, init_sysfilter(sysd))
+ end
+end
+(s::SysFilter)(input) = sysfilter!(s.state, s.sys, input)
+
"""
state = init_sysfilter(sys::StateSpace)
Use together with [`sysfilter!`](@ref)
@@ -36,6 +66,7 @@ function init_sysfilter(sys::StateSpace)
end
"""
+ output = sysfilter!(s::SysFilter, input)
output = sysfilter!(state, sys::StateSpace, input)
Returns the filtered output `y` in `y = Cx+Du, x'=Ax+Bu`
@@ -46,3 +77,5 @@ function sysfilter!(state::AbstractVector, sys::StateSpace, input)
state .= vec(sys.A*state + sys.B*input)
output = vec(sys.C*state + sys.D*input)
end
+
+sysfilter!(s::SysFilter, input) = sysfilter!(s.state, s.sys, input)
diff --git a/test/runtests.jl b/test/runtests.jl
index d6bb9b9848a042552a43fbe1a50f1663e89911fc..20189a9389e479138cbffcab42609fc1e55188d0 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -1,4 +1,4 @@
-using LabProcesses
+using LabProcesses, ControlSystems
using Base.Test
# Reference generators
@@ -6,3 +6,30 @@ r = PRBSGenerator(Int(4))
seq = [r() for i = 1:10]
@test all(seq .== [1,0,1,0,0,0,0,0,0,0])
foreach(r,1:10_000)
+
+function test_sysfilter()
+ N = 10
+ u = randn(N)
+ b = [1, 1]
+ a = [1, 0.1, 1]
+ sys = ss(tf(b,a,1))
+ state = init_sysfilter(sys)
+ yf = filt(b,a,u)
+ yff = similar(yf)
+ for i in eachindex(u)
+ yff[i] = sysfilter!(state, sys, u[i])[1]
+ end
+ @test sum(abs,yf - yff) < √(eps())
+ sysfilt = SysFilter(sys)
+ for i in eachindex(u)
+ yff[i] = sysfilter!(sysfilt, u[i])[1]
+ end
+ @test sum(abs,yf - yff) < √(eps())
+ sysfilt = SysFilter(sys)
+ for i in eachindex(u)
+ yff[i] = sysfilt(u[i])[1]
+ end
+ @test sum(abs,yf - yff) < √(eps())
+end
+
+test_sysfilter()