I maidened my APM2 yesterday. It's running the latest code offered by the mission planner--2.34. I've got the skywalker parameters file from april 2012 set on it.
Just as the subject line says, when I switched to either fbw A or stabilize (didn't try fbw b), the plane inverted. I didn't leave it there long enough to confirm that it was trying to level out, but from the footage and the log playback, I'd say that's where it was headed.
To aid in confiming this, I played the log several times with various sensors checked in the tuning window. Seems that the accelerometer Z axis calibrates to -1000 while X and & axes are both 0. I know that the Z would be offset because of gravity, but noting every time I enabled one of those modes during the flight, you can see the Z axis graph climb up to positive values.
So, I suppose the simple question is: how do I invert the Z axis of the accelerometer? Or, why would this be part of a normal setup?
I'm sure it's worth noting that I manually level the plane--I don't have the acc calibrate on boot. I checked to see if I had done that this time, and I believe I did, based on seeing a slightly sharp shift in the values for gyro & acc.
I had done this once by accident in my multiwiicopter. There it was easy enough to add or subtract a - in front of the sensor's raw term. I have a feeling that's not so much the case in such a complicated system?
Your insight is appreciated!
Do cpontroll surfaces move the direction they should?
Just hold it in your hand in stab mode.
Check the wiki under "inverted". Maybe you have the inverted parameter set.
Thanks for the advice guys!
Inverted mode is set to 0 in the params list.
I believe my roll was inverted in the radio calibration menu. I've re-configured everything again. I did verify proper aileron and elevator direction while on the ground in stab mode, but the prop spun up once I entered the mode, so I may have been distracted by that... is it supposed to start spinning in FBW A and Stabilize modes?
I've re-leveled, re-calibrated, and re-verified the whole thing again, here. Rolling the plane farther increases the deflection of the ailerons, just as one would expect... Yet az on the tuning graph shows a solid -1000, just as it did during the flight. When I invert the plane now, that value climbs up to +1000, just as it did during the flight.
I'll have to get it in the air to try again, of course, but I don't have much confidence that I've corrected the issue.
Can any of you who have successful use of stabilize confirm that when level and calibrated your az value is also -1000? That would settle it, certainly.
Below is a link to the video of the flight. The first mode switch was stabilize, then FBW A, then FBW B. I've also attached the TLOG. For the actual flight, scroll all the way to 79%. I was fussing around with everything else prior, forgetting how fast this system can acquire gps.
Yep, -1000 is the proper value. Just double checked mine and it reads -985.
Prop shouldn't spin in stabilize or FBWA mode as long as you have the throttle back. My APM sometimes gooses the throttle for no apparent reason though (usually when I turn the TX on), so be careful.
Just to be clear, in FBW-A the throttle will go to THR_MIN .
Set in params, so be careful when switching on the bench.
(Found out the hard way with a 18" prop) :)
in the cuise settings, Min, Max and cruise.
Mines set to 40%, so it jumps into life, quite violently.
Hope this helps.
Well, that's not good! The mode description in the manual under "FLY BY WIRE_A" says that...
The autopilot will hold the roll and pitch specified by the control sticks. Throttle is manual.
That's a pretty dangerous error in the manual! One user already injured it seems!
Hope you weren't too badly hurt.
I'm with Jake! I thought A was the safe-on-the-bench one lol
For bench testing, like last night, I just keep my esc disconnected. 18" at 40% must have been very exciting while sitting on a table !
Excellent, thank you! Knowing that, I can look elsewhere for further issues if the next flight turns me upside down again. I suspect it won't, though. I bet I had the reverse box checked on roll and pitch.
It'll be a few days before I can find out, though; we're heading out of town and the plane isn't coming along :(
What is your method for leveling the plane before you calibrate the acc? To get proper level flight, that calibration must have to be very very close to perfect, right?
I put a board under my two rear wheels. (nosewheel plane) With a tail dragger I guess you'd put something under the rear wheel.
I also usually check the manual calibration box. That way I only level it occasionally.
I also thought that in FBW-A the throttle was on manual, but clearly not.
we must be careful, (however it not being completely manual makes perfect sence, as long as you know about it.
The problem is that there's no way to know about it when the manual has the wrong info.
FBW-A should have manual throttle control. It doesn't make sense to have a throttle minimum in FBW-A.