JoystickInput in QGroundControl

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JoystickInput in QGroundControl

Postby jamesbass » Sat Mar 21, 2015 7:20 pm

I have successfully recompiled QGroundControl with the joystick input and widget enabled. I'm able to get the widget to respond to joystick input but it looks like there is no code in the firmware to respond to the mav_manual_control events and that the controls are hardwired to the radio inputs. I will go ahead and try to add the appropriate message handlers to the firmware but if you have any advice on the best approach it would be helpful. Thanks for the great project! PS. Is there a reason why some of the repositories are hosted on google code and others on github?
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Re: JoystickInput in QGroundControl

Postby Max » Sat Mar 21, 2015 7:33 pm

Hi James,

Yes, now you know why the joystick stuff is disabled in AQ QGC. ;)

There's actually some firmware changes in the works to abstract the radio inputs from the actual controls. So a "virtual radio" could be used, eg. via Mavlink. This should help your endeavor. I'm not sure I'd really want to control a MR via Mavlink, but hey... :)

The repo stuff is mostly historical, and with GCode shutting down, we'll be moving the firmwares to GitHub sooner rather than later. It was already planned anyway, but I have to rework a few things like the build server.

Cheers,
-Max
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Re: JoystickInput in QGroundControl

Postby jamesbass » Sat Mar 21, 2015 9:50 pm

Thank you Max for the info! Ultimately my inspiration is to put together some sort of camera based auto navigation system using AQ as inspired by the amazing work of the team at http://flyingmachinearena.org/. The Mavlink route is attractive as it only requires software changes to the existing AQ infrastructure. Since I am planning on indoor flights I'm not super interested in gps navigation or a long range solution. The commented out joystick and libfreenect inputs are very interesting to me for that reason.

I assumed that ETH-Zurich and others were using Mavlink for navigation by looking at the various modules for ROS and the pixhawk documentation. Why would you suggest avoiding that? the lag from bluetooth? range issues? Since I am already using a devo 7e with my ladybird v2 AQ build I suppose I should try the arduino/DSC approach ala http://www.min.at/prinz/?x=entry:entry130721-182227 but it seems a bit messy.

Are there any off the shelf usb dongles that will transmit to the AQ onboard radio?

Let me know if there are parts of the groundcontrol/firmware related to indoor autonomous navigation that I could help work on! Thanks!
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Re: JoystickInput in QGroundControl

Postby Max » Sun Mar 22, 2015 7:03 pm

Hi James,

Mavlink just has a fair amount of overhead attached to it. For direct control I'd think a simpler, more direct protocol would be more appropriate. But that's just IMHO. It shouldn't be hard to try it out, like you say. I'd at least disable most of the other Mavlink telemetry messages so they're not clogging the airwaves (except heartbeat of course, maybe STATUS).

I've definitely seen lots of data errors and re-transmission attempts when using BT to, for example, refresh all the parameters. Reducing the baud rate between AQ and the air radio should help with errors, but of course slows down as well.

If you don't have an actual radio configured in AQ, you could just stuff the radio.channels[] array with values from Mavlink messages. It'd be a quick & dirty way to try it out, at least. With um, lots of bench testing before any motors get spun up ;)

There's some discussion about USB solution in the M4 forum... there's not much out there though, except one $60(?) device for USB to PPM, which you'd then need to plug into a Tx module. Or maybe it already does DSMx... I forget :)

Yea, we need help that's fer sure. :lol: Feel free to jump in anytime once you get oriented. With QGC especially, lots of room for improvement!

Cheers,
-Max
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