Hi DIY community,
Flying this arducopter is turning out to be the biggest nightmare of my life. I have been using a jDrones frame with the standard 850kV motors and 20 amp ESCs. I assembled the frame fairly easily, configured everything and started testing it. After great effort I managed to correct the drift it had been suffering. So I thought of testing some Loiter and thought the GPS would help a little in keeping it in place and not drift off. Unfortunately, that was the worst decision, since Loiter actually did not work at all. It ended up crashing into a building nearby. I was flying on an open ground, with atleast 15m on each side. I was the logs I collected. Could some tell me whats going on? I have sort of convinced myself that the arducopter is not as friendly as it is being advertised. Is it just me or this thing does not work for any noob?
I know how you feel. I was starting out a month ago, and thought that if I got it together all right frame-wise, solder-wise, and TX- config wise, all would be cool, and I could just start flying and playing. Well it was not! I scratched my head over several problemes, and with not much success in reading the manual either, info scattered all over the place. All sorts of stuff gave me some hard days. Almost gave up in the beginning, thinking this is just not working. BUT :
I kept in there and after a while I got a better understanding of things, got help from the community (very responsive), and kept on, and today I am more than happy. I have flown my first Auto, it was amazing watching the self governed vehicle fly the way it had been told by clicking a map! WOW. I have still some problems with adjusting PIDs, and you know what, but when you at last get to a stable loiter, and work your way from there, the rewards are great, I think.
But again, there is a mismatch between the advertising in the wiki, and real life, it is not THAT easy!
I had the same problem in the beginning, LOITER made the copter fly away. I think for me it helped a lot to get the copter stabilized in flight with "auto-leveling" after that it was all another game.
The first steps I take when I build these is to make sure the Arducopter can hold a level hover and not drift in any direction in just stable mode, it should just sit where you leave it, if its a still day with no wind, when it's not drifting off while doing this basic check will give you a great starting place, the PID values should be right for the standard kit with the 850kv motors, what size props are you running? Could you let us know what you did to correct the "drift" as this could be causing issues in the other modes of flight.
When you say you used "auto-levelling", how exactly did you stabilize it? I put it on auto-trim (arm for 20 sec), then lifted off and it kept drifting away. I did some correction using my sticks (not trims), but that didnt really seem to do anything for me in the long run. Could you please tell me step by step (like I know nothing), on how to do it??
Well I fixed a lot of the vibrations on one of my arms that caused it. I took my landing gear out and levelled it on completely flat surface. This cleared some of my tilting and translation. I could still not get it up and have it stay there flat, which I thought was just gyro corrections. (This is what it seemed like in the logs).. I have completely lost hope and do not know what to expect.. Should it be completely still in air when I give it only throttle??
I started a discussion about the topic some time ago here, it should be explaine there :
Basically when you do auto-trim do it in a windless environment (e.g. a gym which I did, and use the sticsk to get the copter hovering as still as you can, It might be a bit problematic if you are not used to RC and helicopters, go easy on the sticks). It made a lot of difference to me!
I think of it as very friendly. What normally would take years of research and development is functional enough that any n00b can build and crash it. :)
There are a lot of little verification and tuning steps, like checking COG, using Auto Trim (you mentioned correcting drift? did you use TX trims or auto trim?) and setting up certain parameters ... it is so user friendly that you might even skip some of these steps and still get it working well enough that it crashes well when you try to do something your quad is not yet ready, by virtue of skipping a step, to do.
There have been some changes which I am not tracking on completely, but generally speaking, I think the order of operations is to get stabilize working well, but some people recommend acro instead, and then working on AH, which can be tricky, then going to loiter, then working on Auto. Each step has its own tuning and some special knowledge about how to switch between modes and what to expect (such as how the throttle operation varies between stabilize and AH.)
I know this does not address your question, I hope it helps to address your expectations.
The brilliance of ArduCopter is not in how "plug and play" it is, as you might expect with some commercial APs using in pre-designed commercial frames, with no variation in the build. It is rather in its adaptability to handling different frames, to being expanded to suit your needs. That adaptability, the potential to get it working well with all different frame types, styles, different prop and motor combinations, and being able to expand on the base system.... that comes at the cost of needing to test several different modes methodically. Unless, that is, you buy it preassembled and pretested from jDrones, where Jani's team do it for you.
Hmm, three responses and all three refers to getting stabilize to work, I guess there might be a clue there ....I dont think it is such a good idea to use the TX trims to get things stable, although at one place in the wiki it says you can (another place says dont), I dont.
I did auto trims (no TX trims),
ensured structural symmetry (vertical motors),
multiple levelling and configurations with and without landing gear to ensure complete flat etc etc..
What else can I do to eliminate any drift I have been seeing??
Slight drift is normal. If the copter is more than 2-3 tilted it can fly away, but less than that is usually acceptable.
I had a look in the logs. You didn't have GPS logging enabled so that made it pretty hard. The copter got a pitch forward command. Was that you or the GPS commanding it to pitch?
In the future, the control mode switch is your friend. It will save you a lot of headache. Just flip it back to stabilize right away and grab manual control. Also, use Simple mode when starting out. It takes one variable out of the equation. These things are not friendly, that are incredible complex. There are hundreds if things to go wrong, mostly on the HW side. But it is incredibly rewarding and addicting.
I think I am definitely getting more than 2-3 degrees tilt, and I have no idea why. I have listed in this discussion all the various steps I have taken, both electrical and mechanical. But it just doesnt stay up straight. I made a mistake by not logging GPS, however that pitch did not come from me. I switched to stabilize as fast as I could and tried to land it, but I am not that great at this. I have almost fixed all the broken things. What do you suggest I do?? I have absolutely no idea on whats going on now?
I am definitely no expert here George, but if I can be of any help I am glad to. The great thing about stabilize (when it works :) is that it immediately gets the copter back in hover, so I have that mode readily available on a switch id something goes wrong.
I had an experience today, I forced my copter away from Loiter using sticks. When I let go of the sticks the copter leaned about 45 degrees and went quite fast to its home position. I was thinking that if there is something wrong with your GPS, it will behave like that when you switch to Loiter if it thinks its Loiter position is way off. (just a thought .... dont know the real relevance....so please dont take it for a fact)
Did you level your copter with the level command. I found this in the trouble shooting guide.
Make sure the CG (center of gravity) of the copter is dead center. Then run the level command on a flat surface. (hold disarm for ~15 seconds to invoke.) You can also fly in auto-trim mode in a windless (important!) environment--any wind will cause the changes you make to work against you when the quad rotates 180°. Hold arm for ~ 20 seconds to fly in auto-trim mode for about 45 seconds. It will exit auto-trim automatically and fly normally. (Don't worry about counting out the time, just wait for the flashing lights to enter either mode.
Try leveling your copter on a level table and see if the horizon is level in the MP display.I f it's not then try the above proceedure.
Geir, I believe my GPS was doing alright as well. I feel it was the drift that caused the crash.
@Greg: I used a level gauge to ensure each arm and the center is perfectly flat. Also I tried the auto-trim as well, but didnt really seem to make a difference for me. It still translated.