Today I did some flight and photo mission tests.  Overall they went OK, but the plane is not tracking the way points properly. One issue I am sure that is correctable is the fact that it tends to meander to them and not go straight from one to the other.  I am sure some PID adjustments may help, but  would welcome input on how to correct this.

However the biggest concern is the fact that on my last test mission the plane headed toward a way point. It missed that way point and kept going.  I let it go probably further than I should have in AUTO mode thinking that it would eventually correct itself, but NO!  After being blown down wind about 3/4 of a mile, it eventually came back when I switched it to RTL.  If some of you could please take a look at this mission and let me know what you think was the cause of the aircraft going off course so far.  This mission is the very last one on the Tlog.  The mission starts going bad at about 87% of the playback.

Also, if you look at the other missions where the aircraft was toward the far East end of the field you will notice that periodically the APM goes into RTL momentarily.  This is caused because I have my Hitec Aurora 9 set up to go into RTL mode when the receiver looses contact with the transmitter.   I believe this s a separate issue from other issues.

I would certainly value the opinion of some of you more seasoned guys.

Thank you.

Bret C

Jack 90 degree manual grid.txt

2013-03-14 15-34-18.tlog

AgEagle ZII 031413.param

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  • I notice that your battery leads are routed directly on top of the APM. This could be the source of your bad compass readings.

    Some science: As a rough guess I would say that your craft consumes up to 20 amps and that the negative battery lead is possibly 4mm away from the magnetometer. If we plug those values (20A, 0,004m) into this calculator we see that the induced magnetic field from the negative lead is 10 Gauss. The positive lead could cancel this out, since the current is flowing in the opposite direction, but because it is further away (about 8mm) it only subtracts about 5 Gauss. The remaining 5 gauss from the closer negative lead is still 10 times stronger than the earth's magnetic field.

    Some things to do:

    • Route all high-current wiring as far away from your magnetometer as your design allows.
    • Route all positive and negative wire pairs close together, preferably twisted together, so their magnetic fields cancel each other out.
    Magnetic fields of currents
  • Developer

    Hi again Bret,

    Can you also tell me if anything could have changed in the airframe to explain a change in magnetic field? For example, if you have hatch magnets did you lose a magnet?

    I know it's not likely, but it will save me a lot of analysis time if I know there may be an external change to explain the change in magnetic field offsets.

    Cheers, Tridge

  • Developer

    Hi Bret,

    I'll have a look at the tlog and get back to you as soon as I can.

    Cheers, Tridge

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