- Index
- » Usage and Applications
- » OpenModelica Usage and Applications
- » Problems with example from...
Problems with example from OpenHydraulics library
Problems with example from OpenHydraulics library
Hello Ladies and Gentleman,
I'm really new to the Modelica language and OpenModelica. I used the book from Michael Tiller to learn some basics.
Now I want to work with the OpenHydraulics library.
When trying to simulate the delivered example OpenHydraulics.Examples.Excavator.DigCycleSimulation in OpenModelica some errors appear.
Code:
[1] 11:07:15 Translation Warning
[OpenHydraulics.Basic.BaseClasses.massFlowRate_dp_WallFriction: 82:9-82:71]: Re was used before it was defined (given a value). Additional such uses may exist for the variable, but some messages were suppressed.
Code:
[2] 11:07:15 Symbolic Error
Zu wenige Gleichungen - unterbestimmtes System. Das Modell hat 2084 Gleichung(en) und 2092 Variable(n).
Even though I changed the language to english the error message appears in german.
It says that the system of equations is under-determined and that there are 2084 equations and 2092 variables.
Code:
[3] 11:07:15 Translation Error
post-optimization module encapsulateWhenConditions failed.
When trying to run this in the SimulationX trial version I'm currently testing this problem does not appear.
Can anybody give me a hint on how to run the example?
I assume when even the example can not be simulated I might experience problems on my own models.
Thanks in advance.
Thank you
Re: Problems with example from OpenHydraulics library
The OpenHydraulics library isn't supported well by OpenModelica yet: https://test.openmodelica.org/libraries … rsive.html
- lochel
-
-
- 45 Posts
Re: Problems with example from OpenHydraulics library
I will group the examples by issue and open tickets for them. We will see how fast we get full support for the OpenHydaulics library.
- lochel
-
-
- 45 Posts
Re: Problems with example from OpenHydraulics library
FINALLY!!!
I been frustrated for a while with this library so, yesterday I took it personally I decided to track down the problem... and I think I did! 
At least, the excavator and several other examples (like OpenCenter) now compiles perfectly!
Is baffling how simple the solution is. It fails because of this model: Basic.FluidPower2MechTrans
And the solution is to move everything in the 'algorithm' section to the 'equation' section
WAS:
Code:
algorithm
assert(V > 0, "Volume in fluid chamber is negative or zero.\n" + "Increase the residualVolume or the stopStiffness");
assert(p_vol < maxPressure or s_rel < 0, "Maxiumum pressure in chamber has been exceeded");
when empty then
Modelica.Utilities.Streams.print("\nWARNING: CylinderChamber has reached end of travel.");
Modelica.Utilities.Streams.print(" This could cause erratic behavior of the simulation.");
Modelica.Utilities.Streams.print(" (time = " + String(time) + ")");
end when;
equation
// medium equations
// the pressure is the same everywhere
for i in 1:n_ports loop
p_vol = p[i];
end for;
...
SHOULD BE:
Code:
equation
assert(V > 0, "Volume in fluid chamber is negative or zero.\n" + "Increase the residualVolume or the stopStiffness");
assert(p_vol < maxPressure or s_rel < 0, "Maxiumum pressure in chamber has been exceeded");
when empty then
Modelica.Utilities.Streams.print("\nWARNING: CylinderChamber has reached end of travel.");
Modelica.Utilities.Streams.print(" This could cause erratic behavior of the simulation.");
Modelica.Utilities.Streams.print(" (time = " + String(time) + ")");
end when;
// medium equations
// the pressure is the same everywhere
for i in 1:n_ports loop
p_vol = p[i];
end for;
...
and that is! so far I been able to play a little bit with the library with no problems.
Mind you, I discovered this yesterday, there could be some other problem somewhere else but I havent came across it yet.
Now Ill try to warn the maintainers of the source, lets see if Im not breaking something else and can make it into 1.9.4! 
Jorge
- JOssorio
-
-
- 2 Posts
Re: Problems with example from OpenHydraulics library
Big thanks to JOssorio for this solution!
However the Excavator example was still not working for me. It gives the following error:
Code:
[3] 14:01:51 Translation Error
[Modelica.Mechanics.MultiBody.Visualizers: 1986:8-1987:83]: PartialModelicaServices is partial, name lookup is not allowed in partial classes.
[4] 14:01:51 Translation Error
[ModelicaServices: 653:5-654:81]: PartialModelicaServices is partial, name lookup is not allowed in partial classes.
Also the PressureCompensated & PressureCompensatedLoadSensing circuits were still not working for me, which I tracked down to the following:
Need to change OpenHydraulics.Components.MotorsPumps.PCLSPump.mo
For the swashPlatePD bloack we need to change the initType from Init.InitialState to InitPID.InitialState
Before:
Code:
Modelica.Blocks.Continuous.LimPID swashPlatePD(
final controllerType=Modelica.Blocks.Types.SimpleController.PD,
k=propGain,
Td=timeConst,
final yMin=0,
initType=Modelica.Blocks.Types.Init.InitialState)
annotation (Placement(transformation(extent={{0,-36},{20,-16}},
rotation=0)));
After
Code:
Modelica.Blocks.Continuous.LimPID swashPlatePD(
final controllerType=Modelica.Blocks.Types.SimpleController.PD,
k=propGain,
Td=timeConst,
final yMin=0,
initType=Modelica.Blocks.Types.InitPID.InitialState)
annotation (Placement(transformation(extent={{0,-36},{20,-16}},
rotation=0)));
- Index
- » Usage and Applications
- » OpenModelica Usage and Applications
- » Problems with example from...
