Running a simulation of a toy problem does not terminate

[freemin7]

Hello,

i tried to port a toy problem from Simulink to this framework.

Cf = 0.03
Lf = 0.0003
RLF = 2.0

model = Model(clock=Clock(0,0.01,4.))

konstLaststrom = StepGenerator(;amplitude=0, delay=0.001, offset=1)

divide = Multiplier((*, /))
iAdd = Adder((+, -))

Intuc = ODESystem((dx,x,u,t)->(dx[1]=u[1](t)/Cf), (x,u,t) -> x, [99.99], 0., Inport(), Outport())

Uq = StepGenerator(;amplitude=100, delay=0.0001, offset=0)
uAdd = Adder((-, -, +))

IntiLf = ODESystem((dx,x,u,t)->(dx[1]=u[1](t)/Lf), (x,u,t) -> x, [1.0], 0., Inport(), Outport())

uRf = Gain(gain=RLF)

addnode(model, konstLaststrom, label=:konstLaststrom)
addnode(model, divide, label=:divide)
addnode(model, iAdd, label=:iAdd)
addnode(model, Intuc, label=:Intuc)
addnode(model, Uq, label=:Uq)
addnode(model, uAdd, label=:uAdd)
addnode(model, IntiLf, label=:IntiLf)
addnode(model, uRf, label=:uRf)

addnode(model, Writer(Inport(5)), label=:writer)

addbranch(model, :Intuc => :divide, 1 => 2)
addbranch(model, :konstLaststrom => :divide, 1 => 1)
addbranch(model, :divide => :iAdd, 1 => 2)
addbranch(model, :IntiLf => :iAdd, 1 => 1)
addbranch(model, :iAdd => :Intuc, 1 => 1)
addbranch(model, :Intuc => :iAdd, 1 => 1)

addbranch(model, :Uq => :uAdd, 1 => 3)
addbranch(model, :Intuc => :uAdd, 1 => 2)
addbranch(model, :uRf => :uAdd, 1 => 1)
addbranch(model, :uAdd => :IntiLf, 1 => 1)
addbranch(model, :IntiLf => :uRf, 1 => 1)

addbranch(model, :Uq => :writer, 1 => 1)
addbranch(model, :Intuc => :writer, 1 => 2)
addbranch(model, :IntiLf => :writer, 1 => 3)
addbranch(model, :divide => :writer, 1 => 4)
addbranch(model, :iAdd => :writer, 1 => 5)

sim = simulate(model)

However the program is stuck on:

[ Info: 2020-05-11T20:31:55.632 Inspecting model...
┌ Info:     The model has algebraic loops:Array{Int64,1}[[2, 3, 4], [3, 4], [3, 4, 6, 7], [6, 7, 8]]
└       Trying to break these loops...
[ Info:     Loop [2, 3, 4] is broken
[ Info:     Loop [3, 4] is broken
[ Info:     Loop [3, 4, 6, 7] is broken
[ Info:     Loop [6, 7, 8] is broken
[ Info: 2020-05-11T20:31:56.43 Done.
[ Info: 2020-05-11T20:31:56.43 Initializing the model...
[ Info: 2020-05-11T20:32:00.388 Done...
[ Info: 2020-05-11T20:32:00.388 Running the simulation...

I also found no way to check whether i missed to add some branch, other than manually where i spotted nothing wrong. I also see not CPU utilization.

[zekeriyasari]

I am very glad that you give a shot to Jusdl @freemin7

I also found no way to check whether i missed to add some branch,

Jusdl is still in its development phase, and currently needs enrichment (and of course logging) of its inspection scope. So, the inspection of unterminated pins/ports will be included in the model inspection stage of the simulation.

What I see from your model construction is that iAdd has an input port consisting of 2 pins.

iAdd = Adder((+, -))

But, you try to connect the outputs of divide, inTilf and Intuc to iAdd.

addbranch(model, :divide => :iAdd, 1 => 2)
addbranch(model, :IntiLf => :iAdd, 1 => 1)
addbranch(model, :Intuc => :iAdd, 1 => 1)

This is erroneous. You should not connect 3 pins to a 2-pin port. Surely this is not your fault as this should also be checked and not be allowed during model construction . (This check will also be include to the package).

One other important thing with your model(by considering just your model construction above) is that the model includes four algebraic loops. Three of those algebraic loops are nested. Although currently Jusdl simulates models having algebraic loops that are not nested, it needs further development to break nested algebraic loops.

It seems to me that the model you are trying to simulate can be constructed more compactly without needing so many components like adders, multipliers, etc. Can you please write share the model equations with me so that I can try to simulate it.

Thank you again for filing this issue.

[freemin7]

After removing the wrong term the simulation stops at 50%. So there is still something wrong.

using Jusdl

Cf = 0.03
Lf = 0.0003
RLF = 2.0

model = Model(clock=Clock(0,0.01,4.))

konstLaststrom = StepGenerator(;amplitude=0, delay=0.001, offset=1)

divide = Multiplier((*, /))
iAdd = Adder((+, -))

Intuc = ODESystem((dx,x,u,t)->(dx[1]=u[1](t)/Cf), (x,u,t) -> x, [99.99], 0., Inport(), Outport())

Uq = StepGenerator(;amplitude=100, delay=0.0001, offset=0)
uAdd = Adder((-, -, +))

IntiLf = ODESystem((dx,x,u,t)->(dx[1]=u[1](t)/Lf), (x,u,t) -> x, [1.0], 0., Inport(), Outport())

uRf = Gain(gain=RLF)

addnode(model, konstLaststrom, label=:konstLaststrom)
addnode(model, divide, label=:divide)
addnode(model, iAdd, label=:iAdd)
addnode(model, Intuc, label=:Intuc)
addnode(model, Uq, label=:Uq)
addnode(model, uAdd, label=:uAdd)
addnode(model, IntiLf, label=:IntiLf)
addnode(model, uRf, label=:uRf)

addnode(model, Writer(Inport(5)), label=:writer)

addbranch(model, :Intuc => :divide, 1 => 2)
addbranch(model, :konstLaststrom => :divide, 1 => 1)
addbranch(model, :divide => :iAdd, 1 => 2)
addbranch(model, :IntiLf => :iAdd, 1 => 1)
addbranch(model, :iAdd => :Intuc, 1 => 1)

addbranch(model, :Uq => :uAdd, 1 => 3)
addbranch(model, :Intuc => :uAdd, 1 => 2)
addbranch(model, :uRf => :uAdd, 1 => 1)
addbranch(model, :uAdd => :IntiLf, 1 => 1)
addbranch(model, :IntiLf => :uRf, 1 => 1)

addbranch(model, :Uq => :writer, 1 => 1)
addbranch(model, :Intuc => :writer, 1 => 2)
addbranch(model, :IntiLf => :writer, 1 => 3)
addbranch(model, :divide => :writer, 1 => 4)
addbranch(model, :iAdd => :writer, 1 => 5)

sim = simulate(model)

The model is based on a small SimuLink example of somebody i know and for whom i evaluate whether Julia is ready for their work flow.
TST.zip Since i have no matlab i use a free version of DiffPlug to inspect the file.

It is obvious that this system can be rephrased as a single (linear) ODE.