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.
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.
 Acro. I had the P for Roll and Pitch at 0.35 and P for yaw at 0.2. Expo on Aileron and Elevator at 60%. I flew it just a bit. I am not into stunts -- no flips! In fact, when I had to choose which 6 modes I would configure, I left ACRO out.
 Thanks for clarifying how yaw worked in SIMPLE mode. It confirmed what I had observed that after the override it remained at the new heading and didn't try to go back to the old heading.
 I'll try out the original yaw option. Is the source code download kept in synch with the version the mission planner downloads?
 arming check -- short throttle bursts are exactly what I have been using to test whether the motors are armed -- the LED is barely visible. I suppose it is what one is used to -- I have the habit of disarming on landing/crash so didn't have the props spinning after a crash.
Wouldn't it be possible to cut pwm outputs when motors are armed ?
So that ESCs will produce beeps through the motor coils ?
To make a brushless motor "sing" you need to directly control the pulses sent to the motor coils in a way not possible with the radio pulses used to set throttle. And if you stop the control signal, there is no grantee that the ESC will go back to "beep" mode again after it has already been armed.
I would choose a middle ground. Instead of having the propeller stand still or spin slowly, why not just jerk the propellers a little every 2-3 seconds to indicate the system is armed.
Why not use something similar to the motor test routine ?
Spinning those motors while they are armed is always a bit problematic. What happens if someone that does not know properly this and goes and moves ArduCopter while motors are armed and suddenly they spin a bit. Even small spin will cause YIKES effect and most probably this guy/gal will throw this expensive device in panic to ground (and goes change his/her pants). Even thou motors were expected to spin but people just forgets it sometimes.
Only time when it would be good to spin those motors is after direct action from the user by radio or what ever. Like after level calibration from the radio, maybe even this motor arming. Ok I have been flying hundreds of quads and never seen real need to have more visual marker for arming and disarming. LED singals has always been enough. You can always check it from the LED's that are motors armed or not. Also if you are not sure that are they armed or not, I always test it by giving small throttle twitch to see if they start to spin or not. Naturally if not ... Ahaaa they are not armed so let's arm them. And everytime when doing this I'm in charge of doing it and know what to expect.
I personally find it rather scary that motors starts to spin by them self now and then. Usually it just means that something is wrong, radio signal is lost, battery running low, electronic made something funny and so on.
And as most of the people knows, I'm living in Asia/Thailand and we have a lot and hard sun here even still I can see LED signal easily.
No matter what, fly safe :)
A problem with that is when you have an unplanned landing upside down, and the motors are still trying to spin.
I'm not sure how low a revs is possible anyway. If 1 rev per second were possible, then fine, but I don't think it is.
I like the motors doing a low rev spin when armed.
It is a visual indication that the quad is armed.
Very hard to see the LEDS sometimes.
I think it is safer to have them spinning slowly - totally agree.