Re: [Paparazzi-devel] Re: Paparazzi-devel Digest, Vol 82, Issue 64

[Andre Devitt]

Hi Felix-
  A couple points on the VN-100:

  I've used both the VN-100 firmware lib and the pprz module. I
noticed the same point that the vn100 really should be classified as
an ahrs. One issue that I'm considering how to resolve is that the
VN-100's heading state output is based on power on orientation, not
true or magnetic north. Any tips on how to cleanly work with the
offset are appreciated. I don't want to use startup gps heading as gps
heading with non-moving vehicle would seem to be not that great. Maybe
I should use gps heading at gps ground speed > 5m/s or similar?

  About the VN-100 firmware / math lib. I've spoken with the folks at
vectornav company and they are fine with contributing the source to
open source community. I think they are not familiar with OSS
community but have no problems contributing. Point of caution to those
using VN-100 Embedded Firmware Library: I've found a few functions in
there that blow up memory, I've been meaning to forward them fixes to
library but have not gotten to it yet. Mostly they are a result of
functions writing the wrong number of floats before returning, pretty
much a copy and paste neglect; other than this I've found the VN-100
EFW to be pretty good.

Andre.


On Thu, Jan 27, 2011 at 1:58 PM, Felix Ruess <address@hidden> wrote:
> Hi Matthew,
>
> I'm not really familiar with the VN-100, just had a quick look and if I'm
> correct it is not an IMU but an AHRS.
> You apparently implemented it as an imu subsystem? So do you just get the
> calibrated and scaled values from the vn100 or do you read out the already
> estimated angles?
> If it is the latter, it should probably adhere to the ahrs interface and be
> an ahrs subsystem, if you read the sensor values it should be an imu
> subsystem.
>
> Now about the ins_vn100 module, I believed it is currently only used for
> fixedwings. Gautier knows more on this.
> This was created before we started merging rotorcraft support properly and
> should be renamed to ahrs_vn100 and also use the ahrs interface.
>
> There are currently some functions in fw_ins_v100.c to use it with
> fixedwings (update the soon to be deprecated estimator we still have).
> Hopefully we will have a proper state interface (position, attitude, etc.)
> and we can get rid of this.
> http://paparazzi.enac.fr/wiki/DevGuide/StateInterface
> Then we can use all IMUs, AHRS, INS things for fixedwings and rotorcrafts.
>
> Cheers, Felix
>
> On Thu, Jan 27, 2011 at 6:08 PM, Matthew Plymale <address@hidden>
> wrote:
>>
>> I was totally unaware of the existence of that module. It's not in the
>> module list http://paparazzi.enac.fr/wiki/Modules_list
>> And it's not listed here
>> either: 
>> http://paparazzi.enac.fr/wiki/Inertial_Measurement_Units#Vector-Nav_VN-100
>> I will look into using this module, thanks for letting me know.
>>
>>>
>>> Message: 1
>>> Date: Thu, 27 Jan 2011 11:46:30 +0100
>>> From: Felix Ruess <address@hidden>
>>> Subject: Re: [Paparazzi-devel] Re: NPS Simulator: IMU Simulation
>>> To: address@hidden
>>> Message-ID:
>>>        <address@hidden>
>>> Content-Type: text/plain; charset="utf-8"
>>>
>>> Another question.
>>> Any particular reason that you decided to write your own using the
>>> VectorNav
>>> lib and not the vn-100 module already in Paparazzi?
>>>
>>> Cheers, Felix
>>>
>>> On Thu, Jan 27, 2011 at 11:17 AM, Felix Ruess <address@hidden>
>>> wrote:
>>>
>>> > Hi Matthew,
>>> >
>>> > great to hear! We really need to work on the sim as well, help there
>>> > would
>>> > be very much appreciated!
>>> >
>>> > Just some comments regarding licensing, etc.: Paparazzi is GPL, meaning
>>> > that if you want to distribute/sell/share your work, according to the
>>> > GPL
>>> > you have to provide the source as well. If you just use it yourself at
>>> > uni
>>> > it is fine.
>>> > But of course it would be great if you could contribute your
>>> > changes/additions/fixes, Paparazzi basically lives from that.
>>> > I also saw that you use the Vectornav VN-100 IMU and firmware library.
>>> > I
>>> > could not find any information on the license of the lib, so I'm not
>>> > sure if
>>> > we could actually put the parts of the lib we need into the paparazzi
>>> > repo.
>>> > On the other hand we probably don't need much of that anyway.
>>> >
>>> > Cheers, Felix
>>> >
>>> > On Thu, Jan 27, 2011 at 2:45 AM, Matthew Plymale
>>> > <address@hidden>wrote:
>>> >
>>> >> I got the simulator working for our quadrotor! I can see the Google
>>> >> earth
>>> >> tiles and our flight plan and all the settings in real time.
>>> >> Many thanks for help with this, the culprit was indeed the -boot and
>>> >> -norc
>>> >> options, along with tracking down a nasty sigfault in JSBSim
>>> >> I hope to write more about our project on my wiki page in the coming
>>> >> days
>>> >> (no pictures yet)
>>> >> http://paparazzi.enac.fr/wiki/BoozUserList#Concordia_University
>>> >> Not sure if our contract will allow us to commit our code to the
>>> >> public
>>> >> repository, as the University technically owns our work. I will check
>>> >> back
>>> >> on this.
>>> >> Again thank you to all who answered my paparazzi-related questions
>>> >> --
>>> >> Matthew Plymale
>>> >> Concordia University
>>> >>
>>> >> Date: Sun, 23 Jan 2011 18:44:10 +0100
>>> >>
>>> >> From: Felix Ruess <address@hidden>
>>> >>
>>> >>  Subject: Re: [Paparazzi-devel] Re: NPS Simulator: IMU Simulation
>>> >>
>>> >>
>>> >>
>>> >> _______________________________________________
>>> >> Paparazzi-devel mailing list
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>>> >>
>>> >>
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