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Building an F450 quadcopter – Setting up Flight Modes

After the first flight there were a couple of obvious items that needed to be addressed.  More flight modes and getting rid of the wobble.

First the flight modes.  

I had only figured out how to set up the controller to allow for two different flight modes (stabilze and altitude hold).  With so many modes available on the APM this seemed like a shame.  It took a while but by carefully following the instructions on this page I was finally able to get myself up to six flight modes by using a combination of 2-way and 3-way switches.

flight modesAlong the way I had an epiphany that the controller sends out frequencies (or something that can be counted) and that the APM looks for values from the different input channels being in ranges (because it isn’t exact).  So a value between 1,231 and 1,360 (for example) can be assigned to a particular flight mode.

Great!  A mystery solved.  Now all those calibration movements make sense.

Not only did I manage to assign the six flight modes, but on the extended tuning I was able to assign Channel 7 to a switch on my controller that would automatically tell the quad to land.  This has been a real life saver because even when it starts going crazy, switching to land will calm it down and bring it down to Earth better than I can do.  

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Building an F450 quadcopter – Beware Idle Hands

 The first time I ordered something from China it was supposed to arrive in 2 to 4 weeks.  It took 7!

Aerosky

When I decided to build a quadcopter I found a kit on eBay that seemed just the ticket.  The price was good and the seller had great reviews but, unfortunately, they were in China.  Expecting the same delays I found myself nosing around various website the following weekend and came across a ready to fly H100 very similar to the one I was planning to build.

The controller wasn’t as fancy as our build (no GPS) but it down from the regular price of almost $500 to just $200.  

My mind got to reasoning this way.

  • The parts aren’t going to arrive for a quite a while, so if I buy this I’ll have something to fly until the other one is ready.
  • Having a pre-built one nearby will help with figuring out where things go.
  • I’ll be able to upgrade the controller and add a GPS later and can then either have two fully features quads or could sell one (perhaps even at a profit).
  • I had a little extra income which would more than cover the cost of this.
  • That price was so good…I’d be throwing money away if I didn’t buy one!

After putting it into and out of the shopping cart a few times, I finally pulled the trigger.  Since it was only coming from California it would arrive on Friday…the parts for the build arrived the Wednesday before!  

Not only that but the weather turned nasty bringing wind, ice and snow with the result that the maiden flight of this machine ended up occurring about 5 minutes before the maiden flight of the our build.

Thanks Mr. Murphy – you did it again!

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Building an F450 Quadcopter – Day 7 – A very low first flight

Having seen one too many videos where the quad flips over on takeoff I was understandably nervous about trying our new baby out.  It seemed that at every turn there were little details that needed to be checked and re-checked.

For example, we checked the rotation of the motors and S. then fitted the props according to their direction.

APM RotationLater I noticed that we had the exact opposite of what was shown on the APM website.  Our props should have looked like this but were not. So, when S. wasn’t looking, I switched them.  

Fortunately I had woken up that morning with an idea that would allow the quad to fly a little, but not enough to flip over if things go wrong.  It didn’t take long before I had it lashed to our table tennis table and we were ready to try her out!

With S. videoing the first test was a spectacular non-event.  I powered up and slowly increased the throttle until full throttle was reached.  We had plenty of noise but absolutely no lift at all!  Then I realized.  S. had been right all along and I had switched the props which were now pushing it DOWN!

A quick switch of the props and we were back in business.  This is when I thanked my lucky stars that I didn’t trust myself to try it without a safety net.  Every time it lifted up it would go wild and try to flip over.  Fortunately the string kept it in place, but it was all over the place and none of the controls made any sense!  See for yourself!

I checked things over again and realized my mistake.  I had plugged the motors into the APM board with output 1 going to motor 1, output 2 going to motor 2 etc. in a clockwise pattern.  However, as you can see from the diagram above, the ONLY motor I got right was number 1!

Switching the connections on the flight controller had us finally up and running.  It now behaved, didn’t try to flip anymore, and I could lift it up and move it backwards, forwards, left and right.  Forward and backwards was reversed because for some reason the APM sets it up to expect the ELE control to be backwards.  No problem, it just took 30 seconds to change that on the transmitter.

While it seemed to be working it was very twitchy and super sensitive to the controls – nothing like my Phantom which was very docile.  

I posted the video on the quadcopters FB page and our good Samaritan made a comment about how twitchy it seemed. I then found out that the latest version of the Mission Planner software has a sliding scale from 1 to 100 where the higher the number the faster it responds.  Guess where mine was set…yup…100!  I backed that off to 80 which seems to have calmed things down nicely without taking all the fun out of it.

basicOne last thing.  Remember I said that my motors were the exact opposite of the picture on the APM website?  I was under the assumption that it didn’t matter as long as they the same rotation was on the opposite corners.  Turns out that is incorrect and that not having it the right way around is going to cause problems with yaw (spinning on its axis), and possibly more.  So, after some gentle teasing by my friends about not knowing how to fit props, I switched the bullet connectors so that they now all spin the right way.

After all those changes I put it back on the “test rig” and what a difference!  It was beautifully smooth and easy to control.  See for yourself.

So, that it is.  There are still many tweaks to do, such as setting up the battery failsafe and adding LED lights, but really the next big step is to wait for a clear day and take her out.  I can’t wait!!

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Building an F450 Quadcopter – Day 6 – Ready to Fly?

AssemblyFinally the weekend arrived and, with the new flight controller in hand, we could get to work.  S. was at a sleepover again so on Friday I performed the ESC calibration and confirmed that in all motors were finally working!

Unfortunately when I tried to run a normal flight test (minus the props) the double flashing red LED told me the pre-arm checks were failing.

I pondered the problem for a while and then realized the FC was in loiter mode which requires a GPS signal to work.  There’s not much GPS signal reaching my basement!  Switching it to “stabilize” mode had it firing up and we were finally ready to put everything together.

IMG_1544I waited for S. to arrive and we set to work.  She installed the anti-vibration plate, flight controller and radio receiver.  I put the GPS post together and she added the GPS to that.  The post had a little hinge on it and I couldn’t understand why, so when S. asked me which way it should go I told her it didn’t matter.  I figured out later that it allows for lowering the mast for transport.  By pure luck it turned out we had installed it correctly.

We had a hard time figuring out where to put the power module and it ended up awkwardly squeezed alongside the battery.  That might need to be moved if we decide to go for a larger battery in the future.

IMG_1556S. checked the motor rotation, installed the props and then, all too soon, it was ready to fly!  It wasn’t pretty but we were both over the moon with it.

S. had insisted that we set up my phone to record a time-lapse video, which I had to admit was fun to watch.  See below.

Not much to do now but give it a test flight, or so I thought.  With the conditions outside being 13f and 20-30mph winds it looked as though we would have to hold off for now.

To be honest I was nervous about this first flight.  I’ve seen a lot of videos where something small or silly caused the quad to flip and when it happens, it happens FAST!  

I went to bed worrying about that and, as is often the way, woke up with an idea on how to make that first flight almost foolproof!

Next post:  The first flight (why second guessing your daughter is a bad idea).

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Building an F450 Quadcopter – Day 4 – Frame Assembly

My daughter was finally able to fit me into her schedule we had a date for 9:30am on Saturday.

We spent a little bit of time on Friday night trying to work out the best way to piece everything together.  To my surprise the APM 2.6 was too large to fit onto the PDB without sitting on the solder joints, and there was definitely no room for the damping plate.  

After much debate, and taking advice from the FB Quadtopers page, we finally decided there was no option but to switch places and put the battery inside and the APM on top.

IMG_1537

Satan’s torture device

First task of the day was assembly of the damping plate.

Let me just say, for the record, the person who came up with the idea of forcing those little squishy balls into those tiny holes on the plates is an agent of Satan.  Getting those things forced through 8 holes without tearing them took almost 45 minutes and included some serious tongue biting to avoid teaching S some bad habits.

IMG_1527

Frame assembly

While I was busy cursing the damping plate S. was busy attaching the frame spars to PDB and then flipping it over and starting on the top plate. Blue loctite was used to keep things secure but not permanent.

IMG_1538With that done it was time for us to attach the motors and secure the ESCs to the frame with zip ties.  Pushing in those little bullet connectors was tough, especially after the punishment my digits suffered putting the damping plate together.

IMG_1539Had I been more confident I would have cut the wires shorter before soldering to the PDB, which would have left less slack.  But with some zip ties we were able to make them secure, if not exactly pretty.

At this point we were ready to attach the flight controller, power module and battery and start configuring.  Getting to this point had taken us to 11:30.  I was all for pressing on but S said “No, I don’t want to finish it yet.  I’m enjoying building it with you”.  Awww!

We talked about what the next steps are and how the flight controller works with the ESCs to control the motors.  This was easy for her because we had built a robot with a Raspberry Pi, so she understands that the power cannot all flow through the computer.  We also took a look at the Turnigy 9X transmitter, which is very different from the Phantom one that she has used before.

9xNoting that the throttle doesn’t spring to the center she asked “How do we make it hover?”

This was a question that I didn’t have an answer for, but a quick look on the Arducopter site and know we know that in loiter or altitude hold mode the throttle just has to be within 40-60% range and it will hold altitude.

For once it is my calendar that is getting in the way.  I have a very busy week ahead and it doesn’t look likely that I will get around to doing anything significant until next weekend at the earliest.

If I’m lucky I will be able to bench test the motors before then.  I might have to sneakily do that before next weekend, as it would be nice to then do that again with S watching and know that it is going to work 🙂

*** Pro Tip ***

curvedUsing a pair of bent nose pliers makes putting the little squishy balls in place simple.  I wish I had those the first time around – I could have avoided a lot of cursing.

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Building an F450 Quadcopter – Day 3 – Soldering!

One of my first jobs involved soldering RS232 connectors by hand.  I was forever burning my fingers and putting on far too much solder so that I then had to spend time trying to remove it from things that it was not supposed to be on.  That was when I was 16, and I still hate soldering to this day.

helpinghandsSo imagine my joy when I discovered that assembling the quad involved soldering about 30 connections (including some to make connectors for another quad).

Since those early days I have learned that the right tools can make all the difference so I bought a decent soldering iron and one of those little helping hands with a magnifying glass.  I also watched a ton of videos on how to solder.

Honestly I dreaded what lay ahead.  So much so that I procrastinated and found all sorts of excuses not to get on with it.  In fact my wife even asked “Are you nervous about this?”  I was.  But eventually, armed with a fresh cup of joe and an audiobook, I got down to work.

An hour later I had surprised myself with how well things had gone.  I had made a charger cable for the Aerosky quad, a battery converter so that I could reuse my Phantom batteries, soldered 12 bullet connectors on the Electronic Speed Controllers (ESCs), and soldered all the ESCs on to the power distribution board (PDB).  Work finally stopped when I realized I needed another XT60 connector and some wire to make the battery connector, which meant another trip back to Cruzin RC where I am now on first name terms with the proprietor.

With progress halted until the next day because the CrusinRC was now closed I turned to the Aerosky quad.  With the battery fully charged (thanks to my new lead) I performed the controller calibration and installed the propellers ready for its maiden voyage. Unfortunately the weather was terrible (freezing rain) so that was the end of day 3.

The next day provided just enough time to finish the last connector and I am now patiently waiting for my daughter so that we can start assembling all the components. She can definitely be a big part of this once she finally deigns to fit me into her busy schedule.   With a bit of luck I can get on her calendar next weekend…:)

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Building an F450 quadcopter – Build Day 2 – Pairing the TX/RX

With all the parts finally on hand I found myself on a Friday evening rolling into a long weekend.  My wife was out with friends, and the kids were all occupied.  Time to make some progress!

I decided to connect the TX/RX and finish configuring the APM flight controller.  I hoped this would be a 15 minute procedure.  It wasn’t.

No Roll Values

No Roll Values

I plugged in the 5 connections between the RX and the APM, paired the remote and started the calibration.  Everything worked except roll (the input used to steer the craft) which behaved as though it wasn’t connected at all.

I Googled, asked on the Quadcopters page on FB (a great bunch of people), and read the TX manual again but I couldn’t find any reference to the situation anywhere.  I was really starting to wonder if I had a dud transmitter and would be looking forward to the hassle of boxing it up and shipping it back.

After taking some time to reflect (a.k.a sulking) I decided to break things down piece by piece.  

First, I found a setting on the TX that showed the values being put out by the controls.  That convinced me that it wasn’t a problem with the stick not functioning as I could see the values changing on all axis.

Now With Roll

Now With Roll

Next I tried unplugging all the connections and adding them back one at a time, each time shutting everything down (software and hardware) and restarting.

When I added the 3rd connection things started working including the roll value!  By the time I added the 5th channel everything worked.  I have no idea why it didn’t work before but I’ll take it.


Sadly all this messing around was a time vampire and my wife would be home any second.  I used the little remaining time to set up an area in the basement ready for the big weekend build and called it a night.

Getting Ready

Getting Ready!

This was the first time I had taken all the parts out of the box and there was good news and bad news.  The good news was that the kit unexpectedly contained a battery strap.  The bad news was that it came with no instructions what so ever.

I still had a ton of unanswered questions.  What is the best way to power the APM?  Should I program the remote to cut the inputs to make first flights easier?  Did I even know how to do that?  Should I mount the APM in the middle (closer to CoG and out of the way) or on the top so that it was easily accessible?

In addition, my plans of building this with my daughter were thwarted by her busy social schedule.

Clearly this project was going to take longer to complete than I had anticipated.  

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