Hi chaps,
I’m new to this, so please bear with me. I’ve been flying 3.1 in Stabilize mode on a new frame for a while, and all good. Today I wanted to start the Auto modes. I went out, tried Alt Hold first and I was as happy as could be for a first attempt. Then I tried Loiter. Before I flew I checked the HUD and it showed 8 satelites and a good 3d fix. As soon as I put it into Loiter it took off fast to the left/roll, I managed to save it by going back into stabilize and got it to land (hard). I checked the telemetry, and it still had lock, but the next time I tried it crashed again, same scenario.
I’m new to checking logs, have done what I can according to the wiki page. I had previously done vibration and compassmot checks, and they seemed good. When I look at the logs now, and graph visible satelites, it shows 0 (or otherwise I’m interpreting them incorrectly)
Please can someone give me an idea where to start. Do I have my compass orientation wrong?
Thank you,
Pete
do you have the .log file as well?
Hi Mark,
I’m hoping the one I’ve attached below is the correct one you’re asking for.
Thanks, Pete
Hi Pete,
Looks like you may not have had a good 3d lock. I looked at your log files and the HDOP never went below 2.2. Actually during the flight it slowly worked its way up to 2.28. You want to shoot for a HDOP of less than 2. My guess is you need to get the gps antenna higher up. What is your current setup?
I had the same issue on my first tricopter. When in loiter or Auto it would just fly off straight in the wrong direction. I had to get the gps antenna up and away from everything. I also had to wrap my gopro in foil to help reduce the interference.
[quote=“renoflash”]Hi Pete,
Looks like you may not have had a good 3d lock. I looked at your log files and the HDOP never went below 2.2. Actually during the flight it slowly worked its way up to 2.28. You want to shoot for a HDOP of less than 2. My guess is you need to get the gps antenna higher up. What is your current setup?
I had the same issue on my first tricopter. When in loiter or Auto it would just fly off straight in the wrong direction. I had to get the gps antenna up and away from everything. I also had to wrap my gopro in foil to help reduce the interference.[/quote]
Thank you r, it is something I suspected. At the moment its on top of the ‘lunchbox’ which encloses the pixhawk. I put it there because I’ve got a folding setup, and didn’t want a long (and vulnerable) mast sticking up. Although it is the highest point it may still not be high enough. I will change it and report back.
Can you elaborate on the gopro wrapped in foil please? My gopro is a good 20cm away from the gps. What sort of interference would I see? Would it be a different hdop with the gopro switched on or off, if there is any interference?
Once again much appreciate your help
Pete
I found out the not so hard way my GoPro 3 put out some RF interference. One time I was flying with the GoPro facing down taking pictures every 5 seconds and so it was probably at least 20cm away from the antenna. I then flew the same mission again and tilted up to up the Gopro to video the same flight. This time the Gopro was probably 10 cm from the gps antenna. When I put it in auto mode it would just flyaway. Same thing when in Loiter. I never crashed but came close. I did some research I found out the GoPro can sometimes interfere with GPS antennas when they are in close proximity.
I found out some people had good luck wrapping their GoPros in aluminum (aluminium for the rest of the world). The aluminum acts as a faraday cage and blocks much of the spurious rf emissions from the processors in the GoPro. Also make sure you have Wifi turned off as this will interfere with 2.4 ghz remotes which most people are using these days.
There is a very simple way to test for this because every situation is different. Put you quad out in the open and watch the telemetry for HDOP with the GoPro off. Let the GPS settle probably 3-5 minutes. Then go over and turn your GoPro on while recording video and see if your HDOP drops. Also look at the map on mission planner to see if you are close to where your craft is.
Now with telemetry recording fly around in Stabilized mode mentally remembering where you where flying or hovering. Then go back and see if the telemetry record shows a drop in HDOP and a jump in location. In my case the GPS would go off by a more than a 100meters. You will see this as a straight line when watching the mission back on mission planner.
Let me know if there is something you aren’t clear about and if you want to see a picture of what my GoPro looks like wrapped in aluminum foil.