I have just set up my first 2.5 with plenty of prompt inputs from Chris and John. Much gratefulness !!!
It has flown and I am now working on the Pids. The first flight was WILD ! I have never seen such a shaking; but it has steadily improved and if the wind would stop blowing I would have it sorted. I would really like some sort of tell tale indicating when the GPS is locked on. Any suggestions
I have a new board about to arrive It's a 2.6. Is that critically different to the 2.5 ? Is there anything that I would need to be specially cautious about.
Best wishes
Peter.
Replies
I think I have a new clue. I notice today, and had not noticed previously, that when I test arm, while attached to Mission Planner, it holds the armed state for about ten seconds and then disarms. Maybe it has always done that but maybe it signals an error somewhere. I have tried this with the arm criteria enabled and disabled. It responds the same way.
Best wishes
Peter.
I am back in the air again. The orange flash, next to the green one is only evident when powered by the USB and attached to Mission Planner. The arm, pause, disarm, cycle; in Mission Planner seems to be a feature of the programme. There is no disarm occurring while 12v battery power is driving the system.
I set the P to 0.1500. The I to 0.1000 and the D to 0. 40 and reset Stabil as my basic mode. (ie FM switch fully up and the Gear switch fully back.) It flew well in winds over 12 knots Control seemed very acceptable. I am still shaking after the last flight and I will be super cautious in future.
I am rally keen to hear what other pilots think of as the priority settings for Acro.
Best wishes
Peter.
I have been working my way through the Flite Modes and have struck a problem. Everything works fine in Stabilise, Loiter and RTL but I came horribly unstuck with Acro, about a week ago and today with Sport. Since the Acro crisis I have set my Geo fence much smaller 50 metres radius and 5 metres altitude.
Today in Sport it seemed a lot like loiter but suddenly it shot up vertically and did not respond to down throttle. At about five metres, the throttle cut and it descended vertically. Again it did not respond to throttle. When it hit the ground (hard but flat) It went back to full power and again got to five metres. By this time I had switched back to Stabilise. It repeated the low throttle, no response, hit the ground etc etc. This Yo Yo process went on for four cycles. With the third hit, half of the undercarriage fled the scene and when the quad pancaked on next time, it flipped upside down. After a few seconds it went quiet.
When I got home Mission Planner gave it a clean bill of health and after switching from Sport back to Loiter, I flew again uneventfully. Clearly something is wrong. I will try to upload my files from today. I am unable to view them as I seem to need a FTML. I think I have succeeded. The total flight duration was about 90 seconds.
Best wishes
Peter
2014-08-04 15-02-39.tlog
Hi Peter,
APM 2.6 requires a GPS unit with an onboard compass or an external compass. If you're compass is one of the enclosed units and not just the GPS square circuitry exposed then you should be fine. I'm happy to help further if you want to post a picture of your current GPS. This was the only major change from 2.5 to 2.6.
Cheers,
David.
Oh, as for telling when the GPS is locked on... You shouldn't be able to arm it if you don't have a lock (if you haven't changed that). You can also tell in MIssion Planner if you have it connected via the USB cable or telemetry. Look for the Sat count and HDOP number bottom left of the map. High sat count (11+ if you can) and low HDOP (under 2.0) is what you're after.
You can also attach a LED to the APM so you can see when it's armed and it has a GPS lock. They are available in a small package with a multicolour LED or you can follow my old instructions here > http://diydrones.com/profiles/blogs/external-arm-and-gps-led-kit-fo.... Also FYI, that's from an old school quad of mine (couple of years old) running APM 2.5 and it DOESN'T have a compass enabled GPS as you can see in the background.
Cheers,
David.
Thanks for that. My GPS Unit is the Ublox 6M with a shield (skirt) It is mounted far aft and is about 60mm above the main power reticulation. I am thinking of fitting an earthed alloy shield above the power supply as extra insurance. At this point my laptop does not have MP in it. I am waiting for my IT guru to come back from his holidays. Somewhere in the shed I have a really great LED which runs on 5 volts. I saw that circuit with the transistor (BC 547) and it looks to be just the job. The Ublox has a huge green led (painfully bright) but if you can bear to look, there is a tiny blue led which flashes. I think that might be indicating a lock-on. My other GPS quads all seem to latch within a minute if they were last used at the same field. But they have huge Leds like cats eyes and I have got used to them as a very positive indicator. (They give a coded count)
A picture will need to come with daylight. Thanks again. Peter.
I promised a picture but this is not what I had in mind. As you know I was working on PIDs and I read that this was best done in Acro mode. The model had been flown previously for about half an hour without any dramatic events. I was very confident that todays test which I expected would take mere seconds would be uneventful.
Due to strong winds I was operating in a sheltered area in front of my house. Before lift off I realised that in Acro mode it was very "lively" but it seemed predictable, there was a small PIDs type oscillation. Suddenly it was climbing fast and vertically and did not respond to throttle. I switched to loiter. I think the climb stopped but it was not descending. I switched to RTL. The calibration had not been done with GPS flight in mind. (Close to house) but landing close to calibration point was still better than probable alternatives. It started to descend, while still reasonably above the calibration point, but was seen to be moving away from that point. As height would have it, it struck power lines and cartwheeled onto the sidewalk. The damage done to the airframe (ply and Meranti) was significant but will be easy to repair.
There is no obvious damage to the electronics with the exception of the pictured crack in the GPS unit. On attaching to the computer the system seems unaffected.
I seem to have got off lightly but in every respect this was (potentially) my worst ever accident. (That's based on 50 years of aero modelling, 3 years with quads) It was utterly beyond my control. I have no idea what I did wrong. I would greatly appreciate drawing on your experience in thinking this through. I must suspect that Acro mode needs to be treated with much more respect than I gave it.
Over to you,
Peter.
Post crash fracture.jpg