Hi all,
So this is the first time I've sought help on here since I got my first APM (2.5 latest firmware). I've managed to make it this far with all the good info here and in the wiki. Here's my kit, followed by my problem.
Stock Gaui 330X-S
Spektrum 2.4Ghz Rx and DX6i Tx
So, I had the above taking off and hovering no problem with the stock ESC's (see here for make up of parts)
The ESC's that come with the quad are reputed as being of low quality so I decided to replace them with something a bit better to see if I could make it fly a bit smoother. These replacement ESC's come widely recommended, so I got some.
Cut a long story short, I cut all the connectors off my old ESC's, soldered them all to the new ESC's and rebuilt my quad with the new ESC's. Eventually figured out how to calibrate them (which I did manually) and I'm confident this has been done correctly (as I did it several times before locating the instructions and doing it properly).
My problem is, quad wobbles and flips immediately after leaving the ground. I've ran through all the troubleshooting steps in the wiki numerous times yet I'm still experiencing the same problem. The only thing I can't get working in the test is the motor CLI test:
Have you run the Motors command in the CLI Setup to ensure that all the motors are hooked up right, turning the right way and the pusher/puller props are on the right motors and oriented the right way?
The motor CLI test simply does not work for me, it just doesn't spin the motors as per instructions. I have no idea why and I promise you I have quadruple checked that I have set everything up correctly.
- All sensors tested and working
- Radio Calibrated - all end points on 100%
- Quad levelled
- Props and motor in correct orientation, I can see which way they're going when they start/stop spinning from full speed
- APM orientation fine (using 'x')
Here's the weirdest thing. If I give the quad even just a little throttle then take my hands completely off the Tx, it'll sit there on the ground, all props spinning but they will very slowly speed up to the point where the quad will take off on it's own if I don't drop the throttle.
Another test I did was to hold the quad while giving it a little throttle. It seems to work exactly how it should when I do this in that it will correctly compensate if I tilt it in a given direction. If I only lightly held it, it tended to start wobbling.
I've tried everything that seems to be listed on the forums/wiki but am at a loss. Could it be that I need to do some tuning of PID's before I can even get it to take off properly? I didn't need to touch a
thing with the stock ESC's to get it hovering ok.
Please see my quick video of it increasing the throttle by itself and the flipping.
Sorry about the "War and Peace" entry. Any suggestions/questions are more than welcome.
Thanks.
Replies
I have other Pixhawk powered multi rotors that are functional. Their own issues but nothing to this magnitude!
I'll stand on the other side of the fence from Will. no offence..... My secret is to keep changing things until it works.
I used 4 of these http:// http://www.hobbypartz.com/07e-flyfun-30a.html
Never flashed em, left all 4 power wires hooked up. My theory is that I don't want all the 5v load coming from one esc and heating it up. Also, they only supply 2amps, which is alot, but I got video tx, telemetry radio, lights and so on. I'd rather not burn up an esc by overloading the 5v line.
They take the cool programming card so no funky stick work to set them up.
My apm2 is on sorbuthane on a carbon deck, and ALL the wiring is below that deck. I did because I thought it looked cleaner, but I found out cf is conductive, so that probably helps keep the rf out of the apm..
Taking a stab in the dark here - This is exactly what my quad does when the battery gets too low. The ESCs are designed to shut off at some (programmable) voltage to prevent over draining your LiPo. In airplanes it's a safety feature but in quads, because one of the ESCs will inevitably shut off before the others, it causes flips.
It's possible you're seeing this manifest in your new ESCs and not the old ones because they have different cut off voltages. If you read the ESC's calibration procedure you can usually set how sensitive to low voltage they are. I keep mine as insensitive as possible.
It makes since that this will happen shortly after takeoff. As you increase the current drawn from the battery the voltage will drop. Depending on your battery it can be anywhere from 0.2 to 3 volts. It may be informative to hook a multi-meter up to your battery and see what the voltage does as you spin up. If it drops much (more than about half a volt immediately following spinning up), it's probably time for a new LiPo.
An easy way to test this is to plug a motor and ESC directly into your receiver. Spin it up for a bit and see if it cuts out on you. Remember, because it's one motor drawing current and not four it may take a bit longer.
I don't think this is a problem with proportional gains being too high. The flip was incredibly sudden. Flips caused by dynamic instabilities are usually oscillatory, not purely divergent. That is, it will wiggle and the wiggles will keep getting larger and larger until it eventually flips, not flip instantly.
Best of luck, I know it's a real pain right now but once you get things working it'll all be worth it
~Nate
I don't know your radio, and it's really hard to see from the picture, but it looks to me like you have channel 1 going to input 3, channel 2 going to input1, Channel 3 going to input 2.
With a mode 2 radio, I thought it was pretty straight one to one input. Depends on your radio though.
Wow. You've got a bucket of trouble, sorry to hear about it.
To be clear, this system was working - APM integrated into the Gaui and hovering - before you swapped ESCs?
To eliminate the 'throttle bump' issue try setting the throttle trim very negative (down). This is supposed to put the 'trip point' of the ESC above moving the throttle stick up. My DX6i is setup in ACRO mode.. DX6i pic I did it that way to eliminate the Ch5 movement with the throttle when set up as Heli. I didn't dig deeper to figure out if I could 'unslave' Ch5 in the radio.
Have you grabbed a log file from the APM immediately after one of these failed launches? It will show the throttle in/out values and could shed some light on the problem.