RTL Confusion

Hi Guys

I've just set up my APM2 and got it flying.

With a friend's help, worked my way through the PPM encoder firmware update and got the throttle failsafe all sorted. When I turn my radio off, the throttle drops to 924 which is below my FS cut.

Didn't fly great (bit drifty) but I upgraded to 2.8.1 and balanced props and things were looking great.

I have channel 7 bound to RTL and have verified that CH7 is changing PWM in the input screen.

I went out flying at the weekend and in my haste to take off as it was starting to rain, forgot to put my FPV cloverleaf on my receiver. First time I've done that and if I had of followed my usual preflight sequence it wouldn't have happened.

Waited for GPS lock (solid blue, (gps says gtpa010 on it)) before arming and taking off.
Took off across the field and about 50-100m away, my video dropped out. Thought it was static at first and banked around to fly back hoping it would come back and it didn't, so I flicked the RTL switch expecting the copter to come back to me (and thus my FPV signal to come back).

It didn't, it just throttled down and landed right above where I flipped the ch7 switch for RTL (was still well within radio range)

It landed in some brush and when I got to it the motors were making a weird half attempting to spin sound and things sounded pretty messed up. Dropped the throttle with no response (at this point ch7 was still flipped) and carefully lifted it out of the brush avoiding the sound. 
Props continued to twitch and sound like they were spinning up and down without actually spinning.

Sat it on the ground and realised ch7 was still enabled (RTL) so flipped it back to non RTL and the motors stopped.

I've been flying multirotors for about a year and a half and started with the openpilot copter control, very little experience with the APM2 though.

If it matters (e.g. to check my alt hold/power settings), i'm flying a lunar lander (quadframe.com) frame with APC 10x4.7 props, 30a plush escs, with turnigy NTM prop drive 2830 motors and a 6000mah lipo.

Params and logs (i haven't been erasing them and i've flown once since this so I attached second to last log) attached below.

Logging mode is defaults

My question is: why did the copter land instead of RTL, or at least try to RTL?

Should it not have at least tried to come back to me, even if my GPS was 10m accurate it should have not just landed straight away.

Thanks in advance,

Gareth

logs.7z

apm2-20121029.param

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Replies

  • I have just enabled my OSD.

    When testing it, I noticed my GPS fix was slower than I'd expect. Moved APM2 (and GPS, onboard) to a uBec.

    GPS fix is < 1 min now.

    On OSD, it reports no fix though.

    Tested RTL in short range, after a while of flying it started working (not right after solid blue on 3dfix light), didn't let it return as it was set to 15m and there were powerlines overhead, but when i flicked the switch it started climbing.

    Current thought is that while the GPS unit says 3dfix, apm2 is unaware of this and thus, this is why my RTL did not work when I needed it to. 

    Without the OSD/Telemetry/USB cable in the field, I have no way of knowing that the APM2 didnt have a fix.

    Next to test: 
    USB cable connected, quad outside, with laptop running mission planner. See if I can see if it is indeed not getting a fix/talking to the GPS chip correctly.

    Could someone advise that if APM2 didn't register a fix (even though the gps light was solid blue) that this would cause the symptoms described above?

  • Gareth, I have experienced the same issue on the flight before I lost a prop.  Clicked RTL on the ground station and it landed. Had to use the ground station to switch to send a stabilize command as the switches on the TX did not do anything.  I personally have not tested RTL since as I am waiting on a replacement motor to arrive from HK.  when it comes in I am going to load the new firmware and see if it corrects the issue.  

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