Monday, January 12, 2015

The KK 5.5 board. Five point five you say? Yes...

Flying quadcopters is a tricky business. They take a lot of math, and fast acting controllers to keep them airborne. One of the early common boards, is the KK board.

Trying to cheap out while buying my second flight controller, I was looking at the alternate boards on HobbyKing.  They had this blue flight controller...

Which I have since learned was, or is, a clone of the original KK board.  It's also known as the "black" board. 

This board, in particular, has a ATMega 328 on board.  And as opposed to what you'll find in a multiwii based setup, three separate gyroscopes.  Sadly, there are no accelerometers, so the board has no way of figuring out which direction is down.

The board doesn't support CPPM.  It doesn't know what horizon mode it.  The board's forward direction can not be changed.  It can't be programmed without an ICSP programmer.  However, it does allow for some onboard tuning.

There's no button on the board, so "on boot options" are commanded via the transmitter, and the three pots on the board.  By swinging a pot to the full left position, you command the board to enter gyro reversing mode.

The board does have a built in arming function,  With the throttle at low, you swing the rudder full right, or left, to disarm, or arm.  When armed a red light shows on the board.

So what does the board do?  You might ask.  Well it supports about a dozen mulitcopter configurations, with one to eight motors, some stacked, some not, and some stabilized by servos.  It's really quite the resume.  But no mater what you fly, it will be in acro mode, all the time.  Because the KK doesn't know what way is down. 

The default configuration is the "plus" configuration.  With one prop leading, as opposed to the usual x configuration most of us are accustomed to flying.  The only way to change that setting, is by flashing new firmware on the board.

These boards retail for $12-16.  I can't imagine a situation where this board would be preferable to a Flip, or Naze.  If you have an unending, burning desire to fly one of these, be sure to pick up a package that also gets you a ICSP programmer.  You should also be buying a set of at four servo extensions so you can wire up the receiver to the FCS.

I think the nicest thing about this board, is that the channels are well labeled.  Unlike the Flip, KK2, or Naze32.

Sadly, the only lesson to be taken from this, is that quadcopter FCS technology has really advanced.   The KK 5.5 is a relic.  A cheap relic, but for $4 more, you can get a Flip based board, so the decision isn't a difficult one. 

Monday, December 29, 2014

Quadcopters - Learning the FPV thing.

Friday was a bit of an adventure. I had a visit with the powers that be, and after getting the all clear from the local judge, I was free to go out and play. As it turns out, so was SwitchElectrician.

SwitchElectrician came over, and we did some flying. He brought his X-Factor and his Diatone #29 / Flip 230.

We got some onboard video of his flights.  There's some good views above Northlake.  Keep in mind, it was really windy during these flights. 

I also got in a few FPV flights.  But only one with onboard video.
It got off the ground, one motor shut off, and it crashed.  No damage beyond having the 720p camera fly off.

He also  did some beauty shots of the quadcopters.  ...  We did do this wrong though.  The photo session was done AFTER we flew that afternoon. 

Since it's my blog, we'll start with my quad.  Here's my X-Factor: 
And the backside. 
 And here are the group photos. 

They're a pretty good looking group of quadcopters. 

Flying FPV is a strange experience.  I can fly a flight simulator without any problem. But the sound matches what I'm seeing.  When flying FPV, the sound of the quadcopter feels louder.  These 250 quads are powerful, and loud.  And can hurt.  Being under the hood makes that whole equation seem a lot more scary. 

Also, SwitchElectrician and I were flying at a big field.  With almost no frame of reference.  It felt very lonely and scary flying in that field. 

When I went to fly on Sunday, I chose to fly in my back yard.  I broke a few more props, but I had a much better time, as I had a frame of reference to work with.

Until next time....

Monday, December 15, 2014

There Are Four Quads.

Deadbug: A method for wiring of electronic circuits that involves attaching the components to a substrate, upside down, and then connecting the contact points, point to point.  

Saturday, I went over to SwitchElectricians place, and we spent the day messing with quadcopters.  It was a productive day, we had three different quads get completed.  

Acro quads are a strange.. They're usually an attempt at the minimum airframe to fly, but often err on the "less than minimum" amount of airframe.  That means you need to get really creative with mounting things to it, beyond the usual "hey this isn't the right size" issues that are par for the course. 

In deadbug style, here's the wiring that I did on the HobbyKing Maltese frame.  Now I'm a little disappointed I have the Velcro on there, it doesn't show my cross wiring job.

This quadcopter is flying on a set of 1704, 1900kv motors.  Spinning 5x3 props.  The battery is a 800mah 2s pack.  The flight controller is a KK clone from HobbyKing.  I'll talk about the board later, but for now, lets say I don't like it very much.  It's flying weight is very, very light.  350 grams IIRC.  

Mounting the motors was somewhat difficult.  The motors have a two available mount patterns.  The ones drilled into the motor, and then a X shape bracket you can put on it to mount to larger motor mounts.  The bracket is so large that it is bigger than the arms on the quad.   The built in bolt spacing is between two of the three bolt patterns on the arms of this quad.  To make it work, I had to drill out the smallest spacing with a slightly larger drill bit.  the washers make up for the larger motor mount holes. 

M2 screws and washers are a pain to work with.... 

The board has a fixed "forward."  So the front of this thing, unless I get some kind of adapter board, will make this a "plus" configuration quad.  When I was test flying it, this shape really messed with my head.  You'll notice the red tape and red prop, I did that before I flew it because I knew my brain wasn't going to handle the plus set up very well.    That said, it did fly, and was stable as could be expected from a board without accelerometers. 

Oh look, more deadbug.   The receiver has moved, and there's a few extra wires hanging off the chassis.  Also, the motor leads have lost 5" of excess wire.  In this picture, the quadcopter has a 3s 1500mah battery in it.  It will fit a 3s 2200 as well.  I haven't tried to see if it will balance with a 1000mah 3s in it yet. 

Speaking of balance, the female balance plug on the right side of the picture, is how we decided we were going to provide power for the FPV gear.  It means we can turn on and off the video gear, without the problems that come from switches.  And it gets the video ground as far away from the motor grounds as we can manage.  It should be "better" but I haven't thrown a oscilloscope on the quadcopter to quantify those numbers.  At minimum, it makes me feel better.

The Naze32 flight controller moved twice since the last photo.  Because the receiver came off the top deck, the cable for the Naze32 ended up being to short. 

Standoffs are a wonderful thing.  To clear the speed control wires, I had to raise the naze32 over the motor deck. Eventually I'll be using the same stack of standoffs to carry my HD flight camera, but that's for another time.  

I'm still trying to decide how I am going to dress the power and signal wires for my FPV gear.  You can see the trimmed plug for the balance connector that provides power to the FPV rig. 

The starboard elevation. I'm a little worried about the receiver location, but it's in a case, and should be able to take any hits. 

 The video transmitter doesn't stick past the chassis, so should be safe.  The front end of the X-Factor is a very, very busy place. 

Doing hobby work at your computer desk isn't recommended.. but it's what I do.   I like how it turned out.  In the next week or so, the flight HD camera mount will be fabbed up, and I'll get my hands on some circular polarized antennas.  (or make them...)

SwitchElectrician also had a project to work on.  He picked up the ultra light 250 racer frame from HK.   We built that up too.  It's flying on some 2204's, 20amp Afro speed controls, a 1.5ah 3s battery, and 5x4.5 props. 

Let me tell you, it wants to move some air.  We need to get it on a scale, but I think it may have a 4:1 power to weight ratio. You can peek in at the winding on the motors, and they're positively beautiful.  I suspect they were hand wound with how the wire is stacked on each pole. 

Saturday was a productive day.  

Friday, December 12, 2014

The Third Quadcopter post.

I ended up with two complete sets of motors when I ordered the parts for the HobbyKing X-factor quadcopter frame.  Since I already had spent $35 on motors, I figured I might as well build a second quadcopter.  So I ordered the $11 HK Maltese frame, their KK 1.5 controller board, and some $6 speed controllers.  

Much to my disappointment, the motor BCD didn't match the holes in the frame.  I had to drill out the holes a little to get enough clearance to fudge the BCD between the 1704's and the airframe. 

As it sits in the following picture, it's 230 grams.  With battery, it's 349 grams.  And it will lose some weight when I trim all the wires. 

Well that's an interesting number.  632 grams.  That's the weight of the X-factor, with a 200mw transmitter, a metal case sony board camera, a HD camera, and a 1500mah 3s battery on board.

It looks like a mess.  I need to shorten the motor wires and do some more cable management.  

I did do some testing the other night, and my $40 goggles work well with my $40 radio set and $15 camera.  Next step, is to fly it.

Sunday, November 30, 2014

Quadcopter, it talks to computers, and it hovers!

Saturday morning, a package arrived. It had bigger motors in it. And, those motors came with all the right screws to mount them. So I got those installed.

Motors need something to make them spin. Those "should" be placed somewhere they'll get airflow.

The frame I'm going to be flying has the sprung lower chassis and the upper "x" frame. I think that to get the most benefit of the shock mounted upper "x" frame, I'm going to try to mount everything I can on the lower pod.

Also, to have the lightest install I can manage, I want to have the motor leads as short as I can manage.. that means mounting the speed controls close to the motors. The closest I can get the speed controls to the motor is on the wings of the pod.  I think they look good there too.

Quadcopters are not stable.  They need a controller to make them manageable.  And even then they can be a bit of an adventure.  As I'll explain later.

Our choice of controller is the Naze32.  They come soldered, and unsoldered, and this time.. we got the unsoldered version.  So out came the soldering gear.  Well.. actually SwitchElectricians soldering gear.

And here's the Naze32 mounted, properly, to my quad-copters top plate.  We chose to mount our controllers up there because the battery is less likely to bash into it, and an impact with the ground isn't likely to cause anything to come up and interfere with it.  Or at least that's the thought.

Mounting the boards where we did, also lead to some problems.  My board is inverted.  And the board assumes it will be right side up and looking forward.  However, that can be handled later.

While I had the soldering iron out, I built the power harness.  I want all of the motors to run the same, and I have a moderate dislike for the PDB (Power Distribution Board) systems out there.

PDB's have a limit on how much copper is available to pass power.  Given that these motors will only draw a maximum of 10 amps each, I doubt a PDB would be a big voltage drop.  Still, I don't like them, and I'm pretty good with a soldering iron.

My harness is a U shape of 14ga wire.  Each speed control is fed by 20ga wire.  I think it looks good, and it keeps the high amperage stuff away from the signal wires.  This setup still needs a few more zip ties.

It almost looks alive here.  Standing on it's tippy toes.  Here we are programming it for the first time.  Mistakes are being made as this photo was being shot.

For lack of damper balls, I have some rolled up cardboard and zip ties holding the "x" frame to the lower pod.  So for now the joint is rigid.  The receiver doesn't care if it gets shaken, so I mounted that on top.

I really like how the back end turned out.  There's an XT60 connector on there because that's what SwitchElectrican had on hand.  I use Deans connectors for the most part.  I'll be swapping that as soon as I get this thing home.

Testing the quadcopter didn't go very well.  Every time I got the throttle high enough to have it fly, it would sort of respond to inputs, then flip over.  Faster than I could do anything about it the heli was on it's top.

This happened three times.  I ate two props the first time, and another prop the second time.  And for the third time around, we flew on top of a towel, which saved the props...

The speed at which the thing was flipping made me think the thing was feeding back into itself wrong.  We sat down and watched a video on how to set up the Naze32.  And while we learned a bit from it, such as what "angle" and "horizon" modes were, that didn't seem to pin down why the thing was inverting so quickly.

And then we took a close look at the setup page.  Both SwitchElectrician and I had our boards in non-standard directions.  So any time the board tried to tip, the controller tried to compensate in a wrong direction.

Once we sorted out the proper directions, I was able to lift off and hover the thing.  However, due to the time of night, I wasn't able to really take it for a flight.

My advice to you, is make sure that your board knows what direction it's in on your airframe, and the motions you make with the airframe match what you see on the screen.

Oh look the quadcopter is home.  It needs a name.  I'm open to suggestions.

Next time, the quadcopter will get it's FPV rig, and it's 720p video camera mount.

Wednesday, November 26, 2014

Building a quadcopter: finding out what's missing.

A couple weeks ago, a youtube video surfaced of people racing quadcopters through the woods. Well, here's the video.

Kinda exciting isn't it? But what does a setup like that cost? How much effort would it take to do.  My buddy SwitchElectrician said he wanted to do it.  I...  well couldn't resist. 

I did some digging, and found a quad frame that looked good to me.  He and I both bought this:

 It's a good looking platform to me.  A solid X shape with a pod suspended on anti vibration balls.  The controller boards don't like vibration, so isolation is a good thing.  Amusingly, it's on the expensive end of quadcopter frames, at an astounding $20. 

Orders were placed.  Items were shipped.  SwitchElectrican and I both got our quad "kits" within a week.

Look, it's a flat pack Quadcopter.

The kit looks pretty complete.  Lets dig in.

SwitchElectrican had contacted me, and told me that his was missing some parts.  I was hoping mine wasn't going to be missing those bits.  So I start digging, and the disappointment sets in. 

You'll notice that the only paper in there is the little business card, with the picture of the quad on it.  There are no instructions, and that kinda matters on this thing, as we'll get to later.  And no damper balls. 

So I started with the bad, lets cover the good.  The aluminum standoffs are all perfect.  The screws and standoffs have good threads on them.  The screws are of high quality.  The milling of the FRP is almost flawless.  Suffice it to say, I'd buy this kit again, and again, and recommend it to others.

The bottom plate is some very thin fiberglass.  It's downright floppy.  But as you can see, it's got nice sharp edges everywhere, and no fuzzy bits like you'd get from a dull cutter.  I couldn't resist starting the assembly.  With eight standoffs, this should end up being a very rigid pod.
 After assembling the pod, I found that the top plate goes on the pod just one way.  This is where a manual would have been handy.  I think it would also help to dictate which side your camera should be mounted on.  

I couldn't help but throw a motor on, and a speed control, just to see what it looked like.  For now the build is stalled until I get the damper balls in. 
Next update should be the completed build, and the first hover. 

Thursday, November 6, 2014

Stinky stuff from China?

I love getting new stuff in the mail.  This time it was a stack of protoboards from China.  When I opened the package though, I was struck by the smell.  It smells like a zoo.  Weird...  Oh well, I get to build circuits tonight.