DJI F450 quadcopter alpha1 release

[pbecchi]

This PR contain an example for testing brushless DC motor. The example is a DJI F450 quadcopter FDM.

[seanmcleod]

Thanks @pbecchi this is much easier to review.

Very initial comment, it looks like roughly half the files have ^M at the end of each line and half don't, looks like some mixture of LF versus LF + CR?

[pbecchi]

Yes it could be since I work on Windows and Visual Studio , I will try to correct all those at first commit.....
I see there is also some automatic check errors, but I dont understand what they are about.....

[seanmcleod]

I also work with Visual Studio on Windows. Visual Studio will typically handle files with either CRLF or just LF and keep it that way, and prompt you when you open a file which uses a mixture asking if you want to normalize them. But there is then also your git settings in terms of how it handles line endings, potentially converting on the fly when pushing to the repo and pulling etc.

However I think I possibly saw these ^M in @rega0051's repo originally.

[seanmcleod]

In terms of the build failures I noticed that TestInitialConditions.py is failing, with a unit lookup failing. I seem to remember that the commit for the BLDC included some new unit conversions for electrical properties, maybe one of the existing unit conversions was accidently deleted?

======================================================================
ERROR: test_initial_conditions_v1 (__main__.TestInitialConditions)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "D:/a/jsbsim/jsbsim/tests/TestInitialConditions.py", line 120, in test_initial_conditions_v1
    self.CheckICValues(vars, 'script %s' % (f,), fdm, IC_root)
  File "D:/a/jsbsim/jsbsim/tests/TestInitialConditions.py", line 168, in CheckICValues
    conv = var['unit'][var_tag.attrib['unit']]
KeyError: 'M/S'

[seanmcleod]

Bit confused about <torqueconstant>. Is this supposed to be a user supplied value for Kq as per - http://web.mit.edu/drela/Public/web/qprop/motor1_theory.pdf

Although this element isn't read in by FGBrushLessDCMotor::FGBrushLessDCMotor(), instead we have the following in the header file.

constexpr double TorqueConstant = 60 / (2 * M_PI * NMtoftpound);

So what is the relationship between them?

[pbecchi]

According to theory Kq (torque constant) can be assumed to be 1/Kv (speed constant ) if we define speed in rad/sec torque in NewtonMeter.
Therefore since torque is in ftpound a unit conversion factor is necessary (the conversion factor is TorqueConstant)

[seanmcleod]

The naming is confusing, nomenclature from the motor theory document:

However your variable, TorqueConstant is a constant conversion factor. Whereas when I was initially reading the source code and comparing it to the motor model document I assumed your TorqueConstant was referring to Kq.

Also given this:

Shouldn't we allow the user to optionally specify the torque constant Kq if they want to model the efficiency more accurately?

[pbecchi]

Yes i agree....

[pbecchi]

Let me answer your questions:
I will fix all line ending in next commit
I forgot to delete TorqueCostant from motor.xlm : you are correct it is not needed anymore.
Regarding unit let me ask you a stupid question( since I still have to learn......a lot ):
Since we added unit definitions on C++ code do we need to add the unit on the properties defined in motor.xml? So for example, I need to write:
<maxvolts unit="VOLTS"> 14.6 </maxvolts>??

[seanmcleod]

I forgot to delete TorqueCostant from motor.xlm : you are correct it is not needed anymore.

Is this because you're working on the assumption that Kq == Kv?

From First-Order DC Electric Motor Model

The torque constant can be simply assumed to be the same as Kv
Alternatively, it can be obtained from motor torque data if this is available.

If so, why not allow the user to specify it optionally, and if it isn't supplied then assume Kq == Kv?

Since we added unit definitions on C++ code do we need to add the unit on the properties defined in motor.xml?

Currently you only have a single set of units for each electrical type, so at the moment it's really optional.

[pbecchi]

Yes i agreeOn Jan 23, 2022 5:42 PM, Sean McLeod ***@***.***> wrote: @seanmcleod commented on this pull request. In engine/DJI_E305.xml:

@@ -0,0 +1,12 @@

+<?xml version="1.0"?> +<!--bldc_engine name="DJI E305"--> + <brushless_dc_motor name="DJI E305"> + <!-- E305 Motor is a DJI 2312E - 960 --> + <power unit="WATTS"> 320 </power> + <velocityconstant> 960 </velocityconstant> + <torqueconstant> 6.1217 </torqueconstant> The naming is confusing, nomenclature from the motor theory document: However your variable, TorqueConstant is a constant conversion factor. Whereas when I was initially reading the source code and comparing it to the motor model document I assumed your TorqueConstant was referring to Kq. Also given this: Shouldn't we allow the user to optionally specify the torque constant Kq if they want to model the efficiency more accurately? —Reply to this email directly, view it on GitHub, or unsubscribe.Triage notifications on the go with GitHub Mobile for iOS or Android. You are receiving this because you were mentioned.Message ID: ***@***.***>

[bcoconni]

I have fixed the conflicts by merging master to the PR. Now it builds successfully.

[bcoconni]

Thanks for the PR. This will give a means to test the brushless DC motor model.
A bit of cleanup is needed before merging:

• Please remove the file aircraft/F450/F450-set.xml as it is not used by JSBSim.
• Please remove unused parameters from engine/DJI_E305.xml (i.e. the parameters power and deceleration_factor).

[bcoconni]

PR merged. Thanks for your contribution.