Please, could those of you who had some nasty crashes tell me how your copters react after a hard crash? Are you able to disarm them? I had a motor fail in flight today and it's not the first time I had a problem like this - motor, bullet connectors, prop failure - I think everybody hits this sooner or later. It was well above ground when it happened - I knew it was going to crash and killed the throttle while it was spinning, and tried to disarm it - it didn't react at all, so the motors are screaming when I get to it and unplug the battery. When I just crash land this doesn't happen - still reacts well, but whenever I had a "flip" (not a software glitch) it just locks up completely unresponsive.

Is this a problem with my setup, or are you experiencing the same?

Thanks for any answers

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Jan,

     I think those are great ideas (except the hammer perhaps).  The separate channel to allow you to kill the engines would be a very nice failsafe when all else has gone wrong.  I started with the TradHeli and for that, we have the one motor powered directly from the receiver and what I've always liked is the extra security of always being able to bring it down if necessary.  Fly-aways are virtual impossible.

     It's possible that we could do more "extreme value" testing.  For example we could fake very large or small values back from the sensors and see what the APM does....just a matter of finding the time.  Perhaps not quite as fast or fun as hitting it with a hammer..but cheaper!

If your APM1 appears to be alive but not responding to radio commands, then I would recommend updating the ppm encoder as described on this wiki page (Note: you need an atmel programmer).

There are a couple of bugs in the original ppm encoder including a weakness for lower voltage.  Most quad owners never see a problem but on my tradHeli (with all it's servos) i saw problem like you describe where it's clearly alive but not listening to me.

In my case there is no PPM encoder because I'm not using APM board but Flyduino Mega+sensors. Receiver is connected with 7 PWM inputs directly to "APM" (software). That's why I'm happy this issue is present also in original APM it seems - I can help debug it for others as well :-)

Well, we would need a reciever controlled relay able to withstand 200A (let's be greedy) - I'm not fluent in electronics so the only thing I can think of to hack into mine is a car headlamp relay :)

Or we could disconnect the signal wires - no amps but ~8 of them. 

Or we could have a switch to disconnect APM from power - even easier but not very nice.

The latter two have the advantage of not killing ESCs completely - you can set up failsafe on them (I saw switch on Tgy Super Brain(? I think) with selectable throttle kill timeout for this - and my ESCs start slowing rotation after signal loss and stop after 5s).

I have similar issue. After crash I'm not disarmed motors (first mistake), I'm suddenly enabled ALT_HOLD mode (second mistake) and motors start to spin in my hands. I'm tried to DISARM, but without success. After this, my friend unplug battery and I'm found that AltHold enabled on RC.

IMHO, DISARM must work in all modes.

add a watchdog.

Aleksey,

     It's hard to say though..because in altitude hold mode you can definitely put the throttle completely down when decending because it has less of an effect than when in stabilize mode ... and you could put the yaw completely left as well...although it's not a normal thing to do..you can imagine a situation where someone does that and is surprised when their copter suddenly falls out of sky.  Of course, is that situation as common as someone wanting to disarm their motors while in alt_hold mode?...maybe not, not sure really.

Yes, something like that would be great to have.  I'm also not sure how to implement it really.  Remember that without the APM alive and able to control the copter it will be tumbling to earth in less than a second..so just stopping the motors instantly is a-ok I think.

You can use this http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=... to power off APM board via RC.

This seems pretty easy to me actually.

http://www.fairchildsemi.com/ds/FD%2FFDP040N06.pdf

A MOSFET rated at 120A 60V continuous, burst current of over 600A.  These are only about $4 and available at Digikey.  All you would need is a receiver controlled switch from Hobby King to drive it.

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=...

The only problem with this one is it appears to need about 7-8V on the gate to fully turn it on.  That's OK if you use that receiver controlled switch to put full battery power to the gate.  You could apply up to 4S voltage to the gate.

You could also power this MOSFET from one of the APM outputs if you wanted.  But the voltage requirement is a problem.  You could two-stage it, with the APM output going to a transistor, which then kicks fully battery voltage to the MOSFET gate.

The MOSFET is WAY better than a relay.

I had this exact thin happen to me last week. I was hovering two feet off the ground, then the quad flipped and hit the deck. all 4 motors were still spinning and i couldnt disarm. I was in stabilise mode, but im still not sure exactly what happened.

As it was my 3rd or 4th flight I havent really played with anything, seems to hover well, im just too scared to let it get far away. and it was only a meter away when it flipped.

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Hello Randy! Could you please have a quick look at my post and tell me what you think about my crash http://diydrones.com/forum/topics/crash-people-please-help thank you!

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