My H-Quad Build

[BankNYank!]

Thanks FinalGlideAus for the info on the APM 2.6! I don't want to do acro with my quad. I just want a nice stable locked in platform to shoot video from. In the future I'm sure I'll want to try out other things the APM will do like the different flight modes and way point flying but for now nice stable video is all I'm going to be asking it to do. It's ordered. Now just waiting for Paul to get it out the door!

I think I figured out the issue with my quad. It's the esc. I switched the esc from the left rear motor (m4) to the right rear motor (m3) and it did the same thing except it flipped to the right rear this time. Looks like I have a weak esc or one that needs some programming. In flight it cuts the throttle, not off, but way back. And at other times, if I bump the throttle up real quick it doesn't respond fast enough and the quad flips over in the direction of the bad esc. I tried a different motor and a different fc and had the same issue. When I moved the esc the issue moved. My money is now on a bad esc. To bad I didn't figure this out before I placed my order with RTFQ! I'm going to email him and see if he can get back to me in time to add a couple to the order.

 

[e_lm_70]

by Mr-Fiero » Sat Jun 07, 2014 7:34 am
Somebody needs to slap me.

I built a hex, a nice one, with awesome vibration dampening as posted in a previous post. everything was tight, 1000Kv RC timer 2830's i think, RC timer ESC's , and lots of custom cut CNC parts. 11" x 5 props. A really nice and tight unit.

but

I thought, hey lets flash the new firmware for arducopter on APM2.5 and see where its at these days. Well, everything at first was perfect in flight. not much setup and flew nice. Was low altitude and just flew around and tried to see how it responded. No GPS functions at all while testing flight.

Then

I wanted to see how it would handle throttle and if it had good payload, so started jumping throttle up and down. All of a sudden, flip, and it was laying on the ground wrong side up. No damage but really, what a piece of crap FC. This is weird because this hex had substantial weight under it (gimbal and batts) and it would of taken a deliberate amount of power to flip upside down. Not just a motor cut-out. Also, it was flyable right after again which says everything is functional. What I did notice, is arducopter now detects its upside down and shuts the motors down with a warning beeper that sounded like it was coming from the ESC at 1 PPS. But atleast the motors didnt stay running cause to disarm arducopter its delayed. Still a piece of .... though.

Yea I could try to figure out from the logs, but I just dont care anymore. Probably a brownout, vibration, defective whatever, but who cares..... My 5 other Harakiri's never suffer from this. So, yes, I have another flight controller for Harakiri and its going on tomorrow.

No, seriously, slap me.

Trust me, its not as simple as a PID being the issue. My PID's are very close as I used to have a hex before, and this one is of same design. Another thing to note also, is that it flies perfectly and is responsive as well. PID's are not the issue. Mode switch is not either because I was not switching, I was keeping it in stabilize only at this point.

It was the infamous out of control "sky drop" as I like to call it. All my APM's suffer this. Its not "if", it is "when" something will happen with arducopter. There is usually no hints as a unit will fly so well for an extended period of time, but all my APM 2.5's x6 units have had this happen. Not ordered at same time for the boards, and not same builds.

Stupid me, I just thought "maybe they fixed it by now".

I'm typing while I remove the APM problem from my hex.

The guy above has long experience and fly tons of hours his copter for work ... so ... hard to say he made something wrong.
Still ... it is his opinion ... I have no experience yet on APM in the air ... I had bad experience with MPNG that is the "port" from APM, but this was with old 2.9 firmware.

About APM 2.5.2 ... this board has nothing less then APM2.6 ... the MAG is configurable to use either internal or external ... so I really don't get the point to get 2.6 , when 2.5.2 does has internal mag, and does also support the external one.

Internal mag, if the power distribution system is done fine, it does not have any problem.
MAG signal does not need to be ultra precise .. an error of +/- 20% will not cause any fly away, just a little bit less precision in going/path to the next waypoint or to keep PH

Anyhow ... you order it already, and you have mag in the GPS ... be extra sure to mount in the right direction the mag with the compass .. it must be mounted without any play ... if your mag is moving around or it is in the wrong direction ... it really can cause mayor problems.

 

[BankNYank!]

The APM 2.6 is already ordered so all I can do is hope that doesn't happen to me.

I went ahead and placed a second order with RTFQ and ordered four more of those esc's. The "bad" esc doesn't get hot or anything. Do you guys think it could be a firmware issue or something? I'm new to this so I have no idea.

I've changed motors and FC's and had the same issue in the same location. Then I moved the esc to a different motor on a different arm and the issue moved with it.

After I placed my order with RTFQ today I made a video of the issue that is happening. I flew around and kept hitting the throttle and rocking the quad back and forth and left and right to try to make it happen. I made two flights. The first one was about two minutes with no issues. I was almost two minutes into my second flight when you see what happened in the video below.

Today it looked like the left front dropped out then the right rear. The right rear is where the suspect esc is. Again my motors were pretty warm, actually warmer than I like them. And the esc's were all only slightly warm. Do you guys think it's possible my motors are over propped? I'll figure out a way to clamp my quad down and I'll do an amperage test and post it later.

 

[e_lm_70]

A overheat motor will not fail like this, and will also overheat the ESC too.

I think the ESC is defected, possibly it get a reset while running for some reason (maybe the internal BEC for power the internal CPU fail) ... I had some ESC that behave like that (luckily on a RC airplane) ... this ESC got sometime for no reason an internal reset, and throttle would need to move back to low position for re-arm it again ...

The easy solution is to trash the ESC ... or just use for bench experiments

 

[BankNYank!]

If you agree that it's the esc then I have a problem. In that video you can clearly see the left front (m1) motor cutting out was the reason for the crash. In the video the problem esc is in the right rear (m3) position. This means I now have two esc's that are malfunctioning. One can be a fluke. Two out of four is not a good sign. And I just ordered four more of these esc's.

 

[cranialrectosis]

How are you mitigating vibrations to the FCB?

 

[BankNYank!]

How are you mitigating vibrations to the FCB?

I am not. As a matter of fact it's in a plastic case that is hot glued straight to the frame.

So you think this may be a vibration issue?? I'll have to see if I can find some foam and give it a try.

Thanks for the tip!

 

[cranialrectosis]

In my Polakium Hex build I use a system of zip ties and hobby foam to mount my FCB.

In my Polakium Quad build and in my WarpQuad build I use little M3 sized O rings between the nylon standoffs and the screw head to suck out the vibration to the FCB.

The longer the rotors you use, the more low frequency vibration I think you will face. The more low freq vibe you face, the more you need to mitigate. On my 370 size copters running 1450 kv motors and 8045 rotors I use the foam. I use the little O rings on the 2000 + kv motors and 5" or 6" rotors.

If you are running longer than 8" rotors foam may not be enough. You will likely also have to balance motors and rotors. I balance and use foam or O rings for the best results regarless of the length of the rotors.

Vibration can easily create an error over time where certain movements can cause the FCB to do really strange things. Also, if the FCB can shift in flight or if the battery can shift in flight chaning CG or changing the FCBs relationship with CG, you can have strange intermittent issues.

Whether or not this is root cause, if you don't mitigate motor/rotor vibe, it will be root cause of something you don't like eventually.

 

[BankNYank!]

If you are running longer than 8" rotors foam may not be enough. You will likely also have to balance motors and rotors. I balance and use foam or O rings for the best results regarless of the length of the rotors.

Vibration can easily create an error over time where certain movements can cause the FCB to do really strange things. Also, if the FCB can shift in flight or if the battery can shift in flight chaning CG or changing the FCBs relationship with CG, you can have strange intermittent issues.

First off thanks for the links. I checked out the pictures and I like your idea with the o-rings.

My props are 8045's and my motors are 1450kv. All my parts are pretty secure. My fc is hot glued straight to the frame and my battery is stuck inside with velcro and it's a pretty tight fit. It'd probably stay in place even without velcro. Up until today I didn't have any of that foam like the kk2 boards come shipped in. But today I got a kitchen scale for weighing planes, quad and parts and it came wrapped in nice foam packaging. I'll try to see if I can cut out a piece and give that a try when I get off work tonight!

Thanks again for the info and for the advice!

 

[e_lm_70]

I don't believe it is a vibration issue

I normaly mount my controllers firm and stick to the frame, and this was never a cause of problem .. actually in one case were I did use some sort of foam ... I later hot glue some edge for make it more tight and it did improve the copter

Clearly if you use 'junky' firmware from APM, you need special vibrations isolation, since APM has some 'strange' control logic that is very sensible to any noise over gyro and acc sensed ... but KK2.x does not have this problem at all

In the video I see front left motor that fail first, what does later the rear right motor is irrelevant.

But if you said that it is not always the same motor that fail first ... then is quite strange

You may have very bad PI on the KK2 board, possibly a too high I factor in autolevel or gyro mode
Try to check the configuration, an maybe report it here

Other option is some lose servo cables between ESC and control board ...

I had copter with high vibration with 10" very unbalanced prop .. and still my KK2.0 had no problem to make it fly just fine ... having the board hard mounted on the frame ...

If you are using KK2.1 ... try to move to KK2.0, this is more vibration safe .. with KK2.1 I have no experience with any firmware except my own one ... clearly mine own firmware is way better ... lol ... seriously even reported by a guy from the net ... his copter for his words fly much better with my firmware then with the 'Pro' version that get tons of flowers from the net

Anyhow ... instead of fly and crash ... you should put your copter on ropes and study what does fail .. once you can reproduce the problem, without crash on the ground ... is more asy to understand and solve the problem

 

[BankNYank!]

In the video the left front failed first but that was the first time the left front ever failed. In the past it has always been the esc that is in the right rear. I even moved that esc to another motor/boom and the problem followed the esc.

I have not adjusted any of the PI settings on the FC. Everything is set as it comes by default. I also tried the kk2.0 board and had the same issue.

I'm off tomorrow so I'll do a complete tear down of my quad and inspect everything and put it up on ropes for further testing. I'll shoot some more video and let you know what I come up with.

As always, thanks for all the help and advice!

 

[cranialrectosis]

BTW much as I would like to, I cannot take credit for the O ring method.

That belongs to Soma, the inventor of the WarpQuad String Theory Frame.

Are you using suppo 1450s with ipeaka ESCs and a KK2.1.5? If so, I have 3 (with the KK2. not the 2.5) and vibration from the frame to the FCB can do all kinds of intermittent, crapola things to you.

Before you completely rebuild, I would try the foam approach.

 

[BankNYank!]

Are you using suppo 1450s with ipeaka ESCs and a KK2.1.5? If so, I have 3 (with the KK2. not the 2.5) and vibration from the frame to the FCB can do all kinds of intermittent, crapola things to you.

Before you completely rebuild, I would try the foam approach.

The motors are suppo 2208/14 1450's and the esc's are the RTFQ fire red series so not sure on the manufacturer. I've tried both an kk2.1.5 and the 2.0 and had the same issue. I was pretty busy today but I will try the foam idea and put the quad up on strings for testing as soon as I get a chance.

 

[e_lm_70]

Assuming you have vibration issues, I would expect a quite imprecise yaw control, so yaw should be drifitng in absence of yaw control ... due to the gyro noise on vibrations

Since you replaced the board, it can't be a bad servo signal from board to esc ... so only option left is a bad esc (in my view)

Now, put he copter on two strings ... let the copter free to move in the direction which is controlled by the esc you did assume it is maybe problematic ... record by video ... and see if you can reproduce the problem

If I remember right you have some new esc on the way ... a quick test/solution is to replace the esc that you have identified ...

If the problem are vibrations ... in theory even lowering the PI setting on KK2.0 should solve the problem ... KK2.0 under vibrations should work better then KK2.1 ... still I had multiple maiden on diffeent copters using KK2.0 , copters rich in vibrations at maiden and I never had this flip over issue ... nor that I read any case on the KK2.0 rcg thread about this problem ... but ... never say never

Once you have apm ... apm has a 16mbit memory and will tell you exactly what did happen in case of flip over

 

[BankNYank!]

I apologize for not getting back to you guys sooner. My grandpa passed away and I have been going through that. But mostly supporting my Mom and keeping her going. He was a vet and the national cemetery did a great service for him with honor guard and taps and all that. I was touched that even the police officer that escorted us to the cemetery got out of his car and stood at parade rest as we passed by.

My Mom loves boating and I bought her a little jon boat about a month ago but I haven't taken the time to get it all setup for her. I decided, given the situation, that would be some good times for her so I've been spending all my free time getting that on the water. We got it on the trailer and did a short trial run before but we officially maidended it yesterday evening. I put her in the back and let her drive us around for about an hour and she absolutely loved it! The only thing I have left now is to put some seats in it. I got those cushioned swivel kind with the backs that fold down when not in use. I think those will be better on her old bones than the hard metal built-in ones.

Given all this, I haven't had any time to work on my quad or even to fly for that matter. However, my order from RTFQ came in today with my APM 2.6 and four new esc's! I'll be done with the boat today and will be back on the quad this evening or tomorrow!

 

[Craftydan]

BNY,

Fully understandable -- I sorry for your loss -- but this is a hobby. The only schedule you have, you set for yourself. We're curious in how your approach fairs to give us ideas to improve our own, but take your time.

Good luck with the refit!