Transmitter failure, but APM saves the day

APM flying a search pattern with a SkyWalker

By Andrew Tridgell [ http://diydrones.com/profile/AndrewTridgell ]

DIYDrones.com

April 26, 2011

After yesterdays transmitter failure, we flew the SkyWalker again today with Jacks Spektrum transmitter. This time everything went very well, and we successfully flew a search pattern over the CMAC field.

The flight we did was:

- takeoff in fly-by-wire-A mode
- switched to GPS loiter, worked well
- switched to full auto, and flew a "mow the lawn" 18 waypoint search pattern over CMAC

The plane flew beautifully and the APM behaved perfectly. The audio feedback from mavproxy was really useful (it called out the waypoint numbers automatically during the flight for example). The wind was quite strong, and the SkyWalker coped well, although its speed upwind was affected quite a lot. From the GPS log, the upwind speed in auto mode was around 21km/h, whereas the downwind speed was around 48km/h, which means we were fighting a 27km/h wind. The upwind track ended up with a lot of curves in it, whereas the downwind tracks were fairly straight.

Tracks for the fully automatic part of the flight are here:

http://samba.org/tridge/UAV/SkyWalker/logs/2011-04-26/f2/CMAC-search.kml

The planned search pattern is here:

http://samba.org/tridge/UAV/SkyWalker/logs/2011-04-26/f2/CMAC-search-plan.kml

as you can see, the wind really pushed it off course!

There are a few photos here:

http://photos.tridgell.net/v/CanberraUAV/SkyWalker/

and a video of the auto-search here:

http://www.youtube.com/watch?v=rUr55J0T4_Q&feature=channel_video_title

We flew with 2x2200mAh 3S LiPos wired in parallel, and after the plane landed we measured the amount of charge the charger would put in as around 900maH per battery. From that, we estimate we'll get around a 1hr flight time if we switch to a 5000mAh 4S battery.

We're now planning on adding the pandaboard and ptgrey camera this week, and we will try a search pattern with the camera in the SkyWalker next weekend. That will give us the image data we need combined with full telemetry (attitude, GPS, altitude etc) to get back to the image processing and 'find Joe' task for the outback challenge [ http://www.uavoutbackchallenge.com.au/ ].

3:31am