2.0.14 is my first Arducopter code. My previous experience has been with MultiWiiCopters and I built and flew several quads with this software.
Wanting to try out UAV/GPS features, I built an APM and today I swapped out the electronics in an existing quad with APM hardware.
I am using a non-standard frame, but the quad flew in STABILIZE mode without any PID changes. So far I have only tried out SIMPLE, ACRO and STABILIZE modes – mainly because I have been test flying in my basement (no GPS signal, and also the available space is smaller than the LOITER radius :-)).
I really liked the Mission Planner, which made code download and setup very easy. Though I had to reverse the Elevator control in my Tx after realizing it was reversed in the first test “hop”. It wasn’t very obvious in the Radio Panel in the configurator that this control needed to be reversed.
Arming: It was a bit disconcerting that arming the motors is almost un-noticeable. I had to stare at the APM to figure out that a previously green LED had now started blinking. The MultiWii code spins the props (at low RPM) at all times when the motors are armed. This is a very useful safety feature and it would be great if ArduCopter adopted this too. The manual states emphatically that the props won’t spin, but I am not sure the reason behind it.
ACRO: after bumping up the P values, and turning up Expo on the Aileron and Elevator controls in my Tx, I was able to fly in ACRO mode. Interestingly, even a small non-zero “I” value made it completely unstable.
The ability to update PID via XBEE is very nice since it makes it easy to experiment with various parameter values.
The next two modes worked better with the expo settings removed for aileron/elevator (back to linear).
SIMPLE: it seems to work, although I have a question about which heading it locks on to. When I overrode the heading with the yaw stick, it didn’t appear to aggressively come back to the original heading. Does it latch on to a new heading after the override? BTW, I do have a compass sensor.
STABILIZE: I found this the easiest to fly with and so far I haven’t changed the PID values. I’ve seen comments that the yaw problem has been fixed in this release. However, I found the yaw very sluggish – almost as though I was fighting heading-hold. I checked more than once to make sure I wasn’t in SIMPLE mode. Also, after it begins to yaw, it tends to overshoot. Then if I center the yaw control, it slowly turns back a little. Next I plan to tweak the Yaw PID to see if it fixes this sluggishness.
Of course, the raison d’etre for Arducopter 2.0 are the UAV/GPS/GCS/Mavlink features and I am looking forward to testing these in the next few days.
Useful review. I also like the idea of some remote indication of arming/disarming, rather like when you lock some cars and hear a Plip Plip sound. If the motors were just to twitch once on disarming and twitch three times on arming, that would suffice probably. What do people think?
Thanks for the test report. We have had slow prop arming indicators in the past, but some users asked us to remove them because they we worried about safety. I suppose we could take a vote to see which most people prefer.
The board does not have a buzzer or piezo speaker on board, so we can't make an audible indicator.
I'd vote for a Motor twitch too.
Just a short twitch, so you would know it is on now...
I've been working on a high intensity RGB_LED Becon Status system for AC2 to help identify the status of
2.) ppm signal
5.)Motor Armed or Disarmed
Well, I've found that spinning props serve as a pretty unambiguous warning that the motors are armed.
Take the case that you've landed the quad and think you've disarmed the motors. You walk to the quad, tx in hand, and pick it up. Now if you accidentally nudge the throttle -- you're toast. With spinning props indicating the motors are armed, that won't happen.
You could say: (a) just don't do it, but it is hard to argue against a visual reminder. or (b) planes have the same problem -- but at least you can pick up a plane in such a way that even if the prop starts up, you won't get hurt. That is pretty much impossible with a quad.
Chris, a configuration option, or even a compile-time switch for spinning props would be nice.
Thanks for the feedback!
I've never flown Acro before. What are your PID settings? There is a little know option in there for flips called ACRO_RATE_TRIGGER. If you're a confidant pilot, maybe try that out. Setting to 4200 should put the copter into wicked flips with full stick deflection.
Simple mode Yaw will reset with each yaw command. Centered yaw stick means hold.
Now that yaw is fixed, try the original yaw controller. In APM_Config.h set:
It's much more aggressive and includes a "brake" for more aggressive stopping of yaw.
Many folks complained about the motors spinning when Armed in NG. It's annoying when you crash that the motors grind away as well. I have gotten used the current setup and prefer it now. For now, give it a chance. You can always test with a short throttle burst.