Arducopter build (hopefully!)

[Robin Kearney]

I thought I'd drop a few posts into this shiny new forum section about the build of my Quad.

I'm not quite sure where the desire to build a quad came from, but a few hours research earlier this year lead me to discover the ArduCopter, which looked like fun and maybe something that could combine two of my hobbies, i.e. flying toys and messing about with computers.

I decided to roll my own, rather than buy a RTF or a kit, so started more research as to what I would need.

The frame shown below is the one I chose, 450mm seemed a manageable size, and I liked the ladder style of the fame which meant plenty of places to tie electronics and what not into.

(Image from HobbyKing.com - hope they don't mind!)

Not really knowing what I was doing and following quite a lot of reading I also ordered:

• Four Turnigy D2836/8 1100KV motors
• Four TURNIGY Plush 25amp ESCs.
• Some 8x4.5 slow fly props, both normal and reversed
• This useful looking PDU board.
• a 3s 2700mah lipo

That was the basics ordered, now I just had to pick a control board...

[Chris Bott - Moderator]

Following with interest Robin. It's one of the many things I'd like to have a go at.

[Tony Read 2]

Yipee!! We've got our own section!

Keep us updated as to progress. I've got a hankering for one of these.

[Biggles' Elder Brother - Moderator]

Hi Robin,

have you taken a look at the ArduPilot - Mega stuff? Could be "the way forward"!

BEB

[Robin Kearney]

Yep BEB, I have. That is the board I am using to control it. The guy who designed the PCB open sourced the design so anybody can make their own. I found RCTimer had stock when I was looking so bought it from them in the end.

As you can see from this pic there are quite a few pin through hole connectoins to solder!

[Tony Read 2]

Will it do aeros/flips?

[Biggles' Elder Brother - Moderator]

Tony - it'll make the tea if you want!

BEB

[Tony Read 2]

Naa, just got a brew thanks!

How do these things work? Do you program in the sort of responses/flight parameters via your PC/laptop?

I'm a bit of a quad novice so my only experience so far is with a UDI UFO.

[Robin Kearney]

Tony, I'm only a beginner, but the way I think it works is you do the initial setup via a USB cable to a PC running some software which the designer of the PCB also wrote and open sourced. Then you can fly it like any other RC Quad.

Beyond that if you add a GPS you can create flight paths and have it fly itself, which sounds quite neat, but probably not that rewarding after an initial play.

Other things you can program from the software is flight modes, so for example it can auto land or 'loiter' which means circle a given spot on the ground. It also has a hover mode which you can engage at any time and it just sits there. I wonder if that is handy if you get into trouble, flip a switch and have it right itself and just hang around

I have had grand thoughts of maybe trying to program it to do flips but I'm someway off that yet so I've parked those thoughts!

r

.

[Tony Read 2]

Flip it, flip it, flip it!

[Robin Kearney]

Tony, I saw a smaller quad being flipped last night in the sports hall we use for our monthly meetings. It did look fun, maybe something to build up to!

So as for the build then, the Arduflyer board I bought was from RCTimer, they provide you with two sets of input and output connectors, straight up or right angled. This gives you the choice of which to use, but of course means plenty of soldering.

This is the board as supplied, with the two different types of connector on each side.

After an hour or so spent with the smallest soldering iron bit and plenty of light, I've got them all soldered in place.

And the same board from the back you can see my somewhat amaturish efforts, but they are all working thank god!

At this point I couldn't reist plugging it into a computer to see if it was recognised and hopefully proving I hadn't blown up a IC with excessive heat!

[Robin Kearney]

 

This is a little video I shot after plugging it into the computer. The software is the open source Mission Planner, which is from the same guys who designed the PCB. Its a free download that seems to just work. Plug in the board, wait for windows to faf about with drivers then the software notices and all is good.

 

 

You can see in the video I thought at the time pitch was reversed, but now I think about it more it isn't. roll, pitch and the compass all seem to work. On to the mechano set then!

 

Edited By Robin Kearney on 07/03/2013 13:23:35

[Tony Read]

As a matter of interest why did you chose that board over the, say Naza one?

[Tony Read]

I'm thinking of giving the Dualsky Hornet a try. Anyone had any experience of these?

[Robin Kearney]

For me it came down to price, I found this Ardupilot compatible board for ~ £50 and the Naza ones seem to be in the region of ~£175.

I also like the open source nature of this, hopefully at a later stage I can start to look at the code and have a play around with some of the internals.

The specially designed plastic cases are back in stock with Unmanedtech so I've ordered one of those today. I didnt fancy having the flight control PCB stuck out in the open! Hopefully that will be here tomorrow.

r.

[Tony Read]

That price sure looks a good reason to buy it!

This may be a stupid question, but what the heck are all those pins for?

[Robin Kearney]

Hi Tony, not a stupid question at all. I only learnt the answer a few days ago, I'm just one page ahead of you

On the left you have 'outputs' to the ESCs. It can handle far more than a quad, although I'm only using 4. On the right are the 'inputs' from the Receiver. I think 5 channels is the minimum required, usual 4 axis and a flight mode switch configured to a fifth channel. I've wired in a sixth just because I had a 6 channel RX to hand.

The row at the top is for expansion - I've not explored this yet, although I do know a pair of those are for the optional camera stablisation. I think you can plug two servoes into these and have the Ardupilot keep a camera platform level irrespective of the angle of the 'copter. Bit ahead of where I am atm!

r.

[Tony Read]

Thanks Robin. Looking forward to seeing you wire it up! Are you going to bling it up with a load of LED's?

When you have finished it here is a good test!

[Robin Kearney]

Love that video Tony, quite impressive stabilisation going on there!

I've had a few deliveries and have made some progress.

First off was the case from UnmannedTech for the APM board, I feel a lot more happy now it is enclosed!

Next up was the GPS, I originally said to myself I wouldn't bother with the GPS until I had proven the copter flew ok, but temptation got the better of me

This came with the correct wire to plug it into the GPS port on the APM so was simply a case of plugging it in and it works. If you plug the APM into a computer via the USB when the GPS is connected you should be able to see it zoom to your location once the GPS gets a lock. My desk is too far away from a window for the GPS to get a lock so I put it out onto the window box which gave it a good view of the sky and a lock was obtained within a minute or two.

Last but by no means least were the 10cm male-to-male wires to connect the 6 channels on the RX to the APM board. Any servo extension wire suffice here, as long as it is male on both ends, but being only 10cm long means keeping the wiring tidier.

So final shot is the APM, GPS and RX all wired up.

I bound the RX to the TX before wiring this up, a new model memory set to aircraft mode is what is needed.

Once you've got all this wired up you can plug the APM board into the computer via a USB cable (which actually provides enough juice to power the APM, GPS and the RX). From there you can calibrate the software inside the APM to your Radio, which is a process not too disimilar to the calibration you do in flight sims like Phoenix, if you have ever done that before.

You can also setup the flight modes at this stage, I simply went for three, all set the same - stabilize mode - which tries to level the copter and maintain heading. Think of it as a helping hand hand, but you still need to fly the thing from the TX. This is the recomended mode for the first few test flights. I'll have a play at getting 6 modes out of the DX8 I use later, apparently it is possible with some mixing on the TX end.

Next up more soldering, need to get the motors hooked up to the ESCs and the 3.5mm bullets onto the battery end of the ESC wires.

More soon.

r.

[Tony Read]

Thats a good case for your control board.

I must admit that from the little I have gleened on the subject the Naza boards are supposed to be a doddle to set up (is that why they are so much more expensive?). But you don't seem to have had a problem sussing out your Ardu at all.

[Robin Kearney]

I've had a good read about the Naza, I think it does look easier to setup. I initially thought it was pricey, but if you compare it to the ready to go Ardupilot, i.e. soldered connectors, in a case, with GPS - I dont think there is much difference in price. I just made my life more difficult by taking the DIY/saving money route

So today was supposed to be a day at work, but... The entire family saw fit to get ill, except me. So thanks to my boss for letting me have the day off at short notice I've spent the day at home. Luck must be on my side because everybody seems to have gone off to bed at the same time and left me with nothing to do. Hmm, how inconvenient.

So first things first, I reamed out the props to fit the prop adapters which came with the motors. I've got a sneaking suspicion I've managed to make one a little wonky, I'll pay close attention to that one when I spin it up for the first time.

Next up I had to widen the holes in the fibreglass motor mount plates, the back of the 2836 motors was just a little to wide to fir through. Then it was a simple job of bolting it all together, very shortly I had what looked like a quadcopter!

More soldering next, firstly putting 3.5mm bullets on the battery wires of each ESC so they can plug into the little power distribution board. Then the job of getting the ESCs connected to the motors, ensuring the front right and back left span counter-clockwise and the other pair span clockwise as per the Arducopter documentatoin. For this I simply connected each ESC to a battery and a servo tester. Testing each as I went.

For now I've just used some nylon hand cuffs to hold the ESCs on the bottom of each arm.

And finally its all done, the APM board wasn't in its case when I took this shot.

Next job is to calibrate each of the ESCs to my transmitter, I'll do this one by one, plugging them into a RX and a power supply rather than using the APM board. I've also been advised to turn off any low voltage cut-off because sometimes one ESC will cut the power shortly before the others, giving the auto stabilisation a job and a half!

Bit of cable management to go and mounting of the RX, GPS and APM board and I think I'm done.

Now if only the snow and 30mph wind would go away somewhere else!

r.

 

 

Edited By Robin Kearney on 11/03/2013 15:59:54

[Tony Read]

Numpty question time!

Why do you have to calibrate the ESC's? Is it to sinc them so they start at the same time? I have not done that before on say a twin a/c. But I suppose it is not so important on a plane, you can hold it with the rudder.

How do you do the calibration?

Not sure about shutting off the low voltage cut-off. You could do serious damage to your battery, better to stop flying early or fit a low voltage buzzer?

Looking forward to your flight test! Good luck, and hope it goes well!!!

[Tony Read]

I've answered my own question today. Had to calibrate a new ESC myself, it's the stick up and down thing. Doh! Should have remembered that! I assume you need to do that 4 times to get the end points the same on each ESC.

Noticed that a lot of people use different coloured props fore and aft to aid orintation. I'm gonner need that plus a big neon arrow on the front!

[Robin Kearney]

Hi Tony, you got it, thats the calibration I meant. Required to ensure all four spin up and hit WOT at the same point I believe.

I'm in two minds about the LVC as well, a way around it is apparently one of these which in essence is a BEC from what I can gather. The APM will draw power from that, ignoring current from the ESCs. When powered this way the APM itself implements a LVC, so you can disable the ones int he ESCs and just go with that.

I've disabled the LVC in my ESCs and I'll report back on how I get on!

Since posting mid week I've actually had the thing i the air, first few tentative flights around the garden have proved to be ok. One prop is not quite balanced, or more likely, not reamed out accurately so I'm going to have a go at reaming out another one.

It needed a good chunk of down trim applying, which is best done in the Mission planner rather than the TX trims apparently, so that required a bit of faffing around, test, land, adjust, test again. Now she is stable though and I'm hoping to get out to a bigger field soon to have a proper test and hopefully trying out some of the other flight modes, like loiter and return to launch.

r.

[Robin Kearney]

re the orientation, agreed. The yellow ball on the front is supposed to help that, but even in my little garden I started to wish there was something else! I can see why people use different coloured props.

r.