https://www.youtube.com/watch?v=UsNdvgwCli8
In what may be the first example of multirotors and snowboards, this young person (and the pilot) make the best of two worlds combined.
The quad has excellent blade tip coverage and was a DIY project.
His build log is located HERE.
-=Doug
This week I visited the National Model Aviation Museum in Muncie, Indiana. If you have never been, put it on your short list of 'to-do' items - seriously. Just inside the main front door, to the right is a double set of doors, with glass windows, that lead into the Claude McCollugh Education Facility (you can see the roll door to the outside in the lead photo). Some local fellows, with their flying trailer, had just arrived before I did at the 10 AM opening time. You can see their trailer just to the right edge of the building. In the room, one fellow had a Futaba shirt on but, didn't look like a factory flyer. I nodded, smiled, and then noticed a multirotor with 'chicken legs' sitting on a far table. I thought, 'That design looks familiar.'
Other fellows were busy setting up cameras and lights for a photo shoot of the multi as well as a 600 or so size conventional heli. Being there to do research on a designer/builder from the 1960's, I didn't have time to chat them up. It was a good thing that I had to make several trips to the car to transfer all the stuff for my research.
On about the 4th trip, stepping out the front door I heard it, that characteristic buzzing that only a multi makes. It took about 5 seconds to locate it hovering over the pond in front of AMA headquarters! The edited Gmap pic below shows where it was located.
I was certain the pilot was running FPV but didn't want to interrupt the crew that was also taking pictures of the multi while it was flying. It hovered in front of HQ for a moment or two and, in spite of the the stiff breeze with bumpy gusts, held steady and then began to move up and toward the lower left of the Gmap image above. Not having time to enjoy watching it, I grabbed what I went to the car for, went back inside with a big grin, and continued my research.
An hour or so later on yet another trip to the car, I saw the multi sitting behind the trailer on a Pelican box with several folks standing around it. Now was the time to engage them. The closer I got to the multi, the more certain I was of the product.
'Hey there!' I said. 'Is that a 3DR multi?'
'Yep. An X8.' (I knew it. Those 'chicken legs' were a dead give-away.)
'I saw you flying earlier, was that FPV?'
'No. It was autonomous. We are flying for a local TV station story about drones.'
(That explained the photographers and long lenses they were using while it was flying.)
My grin got even bigger on hearing that. The pilot went on to say he was running APM 2.6 with the 3DR radios. He told me he had a Pixhawk too but had not put it in an aircraft yet. I told him about my friend John Githens and his Pixhawk in his Safeflight airframe (too bad about SF) and how he is building up an XPro Heli project (I will say no more to let John tell that story). We parted after a bit more chat and the pictures you see below.
If that is not complete proof that the AMA is not against multirotors and autonomous flying, then you simply are not paying attention to what is going on in the world today. Even though the X8 was running autonomous, the pilot still had his TX in hand, ready to take over in the event something went awry.
The contrast of what I was researching and the aircraft sitting in front of me could not have been greater.
Visit the NMAM. The collection is huge and a real 'drone' is part of the collection.
This was my first trip to the NMAM, certainly not my last. The staff there are friendly and engaging. The archivist I was working with was wonderful and a credit to the museum (Thank you SO MUCH Jackie!).
How was I to know that the technology of today would be present when researching the past?
Truly, this is a great time to be alive and an even better time to be in the hobby!
-=Doug
Why did I wait so long to go to Triple Tree Aerodrome? The facility is fantastic and literally a gem less than a hour from my house.
I brought my two Arducopter quads and spent a huge amount of time letting folk hold them, and pour over the details. There was so many folk wanting to talk about them, I did no flying! Multirotors were present but none on the flight line while I was there today. The Instructables Wide-Body Quad (foreground) drew numerous questions simply because the build materials were something everyone that picked it up could identify with. More than once I heard, 'I could build one of these!' I sent many folk off with my card, email address, DIYDrones URL, and Instructables URL. Most folk had not heard of 3DR or either of the URL. Outreach (marketing) seems to be a common activity for me.
This was more of a scouting trip of me and my traveling partner (that's his sailplane before the P-51). He got to see more aircraft than he knew existed. I got to talk with many great people and we both plan to fly when we go back to TTA.
Next time I will be sure to put on more sunscreen than I did. It stings when I smile but it is a good feeling.
Yes! Another APM 2.5 powered quadrotor took to the air in South Carolina. All that energy, time, effort and planning paid off this evening with the maiden flight of my entry into the DIY Drones sponsored Instructables Drone Contest. The build is HERE.
The idea behind this tube and plate project was to reduce the amount of hardware and aluminum used in an effort to reduce weight and cost. The ultimate goal would be a lower cost build that high school kids could afford. Of course a DJI clone air frame is cheap, but as I mention in the Instructable..
Creating/making uses cognitive processes and develops/enhances motor skills.
I chose not to use GPS on this build, again as a cost reduction effort and motivation for a school build. It would be a great project for a STEM program. A different motor mounting method was used for this build...
Rather than fighting to access motor screws through a couple of holes in the bottom of the arm, the arm area below was machined away to make it easy to install the screws. I used the same 'angle mount' idea from my first quad but as these motors were larger, I had to machine some relief into the side walls to allow the screw heads to clear. Sure, I could have reduced the heads of the screws or perhaps found some screws with smaller heads but, this fix provided the simple fix. (Psst... hey 3DR.. if you 'borrow' this idea for AC-4, I will be flattered.)
I am working on my new CNC machine so it was not ready to make the holes for me. I devised a jig, used on the previous quad for marking the holes on the arms.
The width of the jig is the width of the arm material (0.75 in square). The jig straddles the arm and then the holes are marked.
So, how did it fly? Not bad considering I didn't check the battery level prior to the flight. The flying weight of the WBQ was just under the weight of my first quad. The difference was this quad uses the heavier motors (gold vs purple). I was surprised by this when I pulled the motors out of their bags. The motors were 3DR units bought off a DIYD member who had posted them in the Buy/Sale/Trade forum.
Three throttle up/lift off runs were made: Throttle Out is graphed below.
The first hump was to ensure that the controls were right way around. Some tendency to roll right was noticed but with almost no tuning of the PID variables, I was not surprised. The second cycle, obviously longer was more relaxed and I was able to almost take my thumb off the directional stick. By the third cycle it was becoming fun. As the battery faded, you can see that I commanded more throttle to maintain hover..until the APM finally decided the battery was done. Stabilized mode was used for this evening's flights.
Pre-flight problems? Yep -- mostly just two:
If the two problems had not surfaced, I had hoped to get my wife to take some photos. Alas the tests were done near the cover of dark and in partial carport lighting shining onto my driveway. I do want some photos of it in the air to update the Instructable build and to show the skeptics that it really does fly.
My plans for this quad are mainly to educate and demonstrate that the material costs for an quadrotor can be held low but still not utilize what I call 'Minimalist Adaptations'. There still exists a need for young people to take raw material, use their minds, and create something interesting, useful, and fun. The greatest benefit is they might learn something practical in the process.
Build on!
-=Doug
It is old news to some folk but the 2013 Instructables Drone contest ended on July 15 and the winners were:
(Note: Author names are Instructable member names. Several are DIYD members with different names on this site.)
Grand Prize Winner (Prize: RTF 3DR Quadcopter Kit and an Instructables prize pack including a robot t-shirt.)
DIY (Drone It Yourself) Kit v1.0 by javl
First Prize Winners (Prize: 3DR APM Autopilot Kit with GPS, Telemetry and Voltage Sensor and an Instructables prize pack including a robot t-shirt.)
Build Your Own Eco-Quad Copter from Reused and Recycled Materials by KT-AZ
Cheap, Sturdy, 1-Hour Quadcopter by marhar
A Wide-Body Quadrotor - designs and ideas to build your own. by vtxstar
Second Prize Winners (Prize: 3DR T-shirt and an Instructables prize pack including a robot t-shirt.)
Laser Cut MultiWii based quadcopter by dylanfm
Building Quadcopters, Drones and Uav's- A explanation and easy build of a basic Quad. by eben89
Solar Plane by jeffmazter406
3D Printed Ornithopter - Micro UAV Drone by Mizchief100
Brushless Gimbal for Aerial Photography Drones by oesti
Runner Up Winners (Prize: Instructable prize pack including a robot t-shirt.)
iPod AR. Drone flying spy camera at Brookstone and Apple smart phone DRONE by Parrot by GREENPOWERSCIENCE
How to build a Multirotor by Jared_Reabow
Black Eagle aerial mapping UAV by Justinvent
3D Printed Sumo Robot with High Traction Wheels by kmmarlow
Waterproof, Crashproof, Homemade Drone Airframe by mcornblatt
Our Drone by Michael_Bell
MAKE YOUR OWN TRICOPTER! by pawanvs99
Autonomous drone that you already have in your pocket! by prubeš
Canon Remote Shutter for R/C by squiggy2
At total of 45 entries were made in the contest and a wide variety of subjects were covered.
The Instructables Drone Contest page is HERE.
The original DIYD blog post announcing the contest is HERE.
Yours truly was a First Prize winner and I appreciate the new APM 2.6 setup. It will be employed in a DJI F550 Hex build (one of several builds on the bench at this time.) Additional thanks to go John Githens, DIYD member and webmaster of DroneSpeak.com, for his suggestions and editing efforts on my entry.
Thanks also to Instructables for the prize package (1 year Pro membership). If you haven't visited Instructables before, you are missing out on A LOT of amazing community sourced DIYD projects. Almost everything you can imagine is there. I have been a member since 2008 and it simply took this contest to get me off the lurker list and active. You should check it out.
In my opinion, Mark Harrison should get a Community Award for the number of views of his Instructable.
Mark is a continuous supporter of RC activity and had already won in a previous Instructable, the Launch It! contest, with his 1-hour quad project.
Many thanks again to 3DR and DIY Drones for sponsoring the contest.
-=Doug
Using EC3 connections on my quad was a good idea...except when it applied to the AttoPilot 90A sensor from SparkFun. The goal for adding this sensor to the system was to be able to remove it cleanly if needed. The sensor pcb design was changed (from earlier pics in the Wiki) to provide a clean installation of Dean's connectors. What to do? Adapt and Overcome! Behold my solution!
And from the back of the audience I hear "Yeah? So what?" Well the 'what' is the constant challenge we as hobbyists face to take parts and components from different maunfacturers and adapt them to our uses. Have you read the thread on adding this small part? To save you the trouble of looking for it, HERE. Imagine the confusion on the part of the hobbyist who asked if the sensor should be getting hot enough to melt the solder! Wow. The first task I performed after getting a successful adaptation to EC3 was checking for a direct short of the battery connection - none was found. (whew!!) The second task was to insulate the power connections to ensure a short was not added accidently while in use (or crashed).
The solution? Hot Glue! The low temp variety of hot glue guns is cheap and cheap to use. Both sides were sealed off and then tested for mechanical strength. Next was to integrate it into the quad and set it up via Mission Planner. The above linked instructions worked flawlessly to set up the sensor. There is some confusion if you should subtract the 0.3V from the actual measured output from the PDB to the APM. I subtracted it anyway - the MP prompts said I should even if it is contradicted in the Wiki instructions.
The actual function of the sensor can be seen after the APM is reset. It can also be tested with the CLI under the 'tests -> battery ' command string. NOTE: The CLI prompts you with a "Careful" mesage. THIS MEANS THE MOTORS WILL BEGIN RUNNING! ALL THE MOTORS! I did have my propellors removed prior to making the mod but if you, dear reader, decide to add this and perform the CLI tests.. REMOVE YOUR PROPS.
What you see above is the output of the CLI while the battery test is running. Note that 'Careful' actually blends into the 'Hit Enter to exit' string. When I hit Enter, the screen stopped updating but THE MOTORS CONTINUED TO RUN! I tried various commands from 'exit' to 'Cntr-C' to 'stop battery' all to no avail. The motors stopped spinning when I clicked on the 'Flight Data' icon at the top of the screen. I suspect the command string that is sent to the APM to shift from CLI to Flight Data mode flushed the command registers of the battery test states.
The last part of this tale will be a photo of the AttoPilot sensor as installed on the quad. It is installed prior to the PDB on my system but after the arming plug harness (covered in a previous blog post HERE). Thank you for reading this far and I wish you success should you choose to add this neat device to your system.
It took me a little while to learn what most of the switches and buttons on my DX6i could do. This past weekend the Trainer switch was assigned to start the timer in a count up mode.
Behold!
With my EFlite 30C 11.1V 3200 mAh battery almost 7 minutes of mostly hovering flight was achieved (no touch down at all until exhausted).
"Is that all you get?" comes the question from the group.
To that end one issue has been my conservative approach to charging the battery. Keeping a battery cycle log seemed like a good idea and there the evidence can be seen that although a few balancing charges have been made, the charge rate needs to increase. The cell values of the charge prior to this flight were: 3.96, 3.97, 3.97. The first couple of cycles saw 4.2V nominal. I seem to remember dropping the charge current to 800 mA. The heli buff at my LHS keeps his cells at the 4.2V level.
I think this battery can handle more, don't you?
Oh, did I tell everyone on the 3DR and APM hard/software teams how happy I am with the way this copter flies?
WOW! It flies like it has rails and I haven't even adjusted any of the PID settings or any other variables, just TX trim. Many times I have simply held the TX in my right hand and enjoyed watching her sit in the air. Hi-5 to all the devs. Why anyone would want another autopilot is beyond me.
So, if you read this, and you have some data, why not respond with your flight times. Once the battery is topping off better, I am sure the time will be closer to 8 minutes. Cutting weight would help on this bird but.. I won't complain about her weight if she doesn't complain about my flying. ;)
Of course if you have two batteries, half my weight (now at 3.4 lbs/1.5 kg with battery), then you will stay in the air longer.
This build is a trainer/development platform. The next build may be also based on the 3DR frame but the goal will be to cut frame weight to allow 2 batteries.
I've got the multicopter monkey on my back now...and I love it.
It was a fair certainty that Chris Anderson couldn't make it on August 23 to the local radio club and discuss the state of the art of DIY drone technology. On the other hand, he would have raised many smiles at the thought of attending the Anderson Radio Club monthly meeting! My best effort was applied though and everyone in attendence left with more knowledge than they arrived with.
My mostly home-brew AC Quad definitely peaked everyone's interest. Very few were aware of the capabilities of these aircraft and once a 3D lock was achieved by the GPS board, they were very impressed with Mission Planner showing exactly where the aircraft was located. I then explained that the APM2 and related software gave the vehicle the ability to execute a flight plan and if there were cameras or other instruments on board, they could be employed at the various waypoints entered in the mission plan.
The audience was diverse and was made up of a graduate student in CompSci (at Clemson - he was very interested in the code), retired College Professors, former servicemen, business owners, and others I have know for years in the local community. As nearly all were Amatuer Radio operators, I tied community service use of the AC Quad into our ham work by suggesting we could provide eyes in the sky in areas we often go such as disaster stricken locations. With professional relief agencies usually overwhelmed, we could use FPV to look over into neighborhoods with blocked access due to fallen trees and other storm debris. Another idea was to use the Quad to lay out the pull lines/cables we often use to drape over trees for wire antennas. How about a small radio repeater that we could deploy onto the top of a high building as a temporary communication node? We could drop FRS radios or other communications devices into areas where cell and land line communications were down. The lists will grow as others realize what can be done with this technology.
I discussed the current legalities of the technology and how the FAA is collecting information about their mandate to decide what will be done about non-hobby/volunteer uses of the technology. A tour of DIYDrones.com was provided and I am certain that hits to the site from this area of the county went up for the next 12 hours or so.
Also discussed, as the display on the screen shows, is the lack of 6M Amateur band radio gear for RC. There is a minor ripple in the ocean by the MS2K folk employing classic old RC TX cases and gimbals with new electronics. Alas though, there is little motiviation to use that segment of the spectrum anymore with the overwhelming advances in Spread Spectrum radio gear at 2.5GHz.
The presentation was wrapped up with the short video my friend John helped me edit. HERE is the link.
It was a busy weekend. One of my earliest concerns with this project was the lack of an ON/OFF switch that could handle the current of the system and that would not look like something from an old junk box. I wanted it to be easy to use, easy to access (translate: no where near the propellors), and completely remove the battery supply in the event of an unfortunate event.
Enter the Schumacher ArmSafe Arming Kit.
This kit comes with 10 gauge wire and the hardware for nice installation. I didn't use the wire supplied but used 13 gauge wire from my LHS.
After measuring the wire paths and checking the sexes of the required connections (I have EC3 on the PDU and battery), my sketch was turned into a harness.
After some razor saw work with my favorite plywood, some light drilling, tapping, and other fabricating, the harness was installed on a side deck next to the APM2.
The home brew camera mount was pulled from a camera pistol grip project from last year and adapted to the arming deck. Behold the complete installation!
A view with my Philips Qvida pocket camcorder installed...
This weekend was also spent running down the battery on the Arducopter multiple times. The tether system is working fine. One flight effort was at my friend John's house lauching off his lawn. That was a different experience because the interaction of the grass tugged at the legs causing a different type of compensation for hovering. At times I had to abort due to hanging on the grass and tipping too far over.
Another funny thing to watch were leaves and bugs that happened to be sucked into the down draft. Think leaf mulcher.
I am presenting a program on drones/UAVs at the Anderson Radio Club meeting this Thursday night. John helped me edit some of my video and some he shot into a short movie to present at the meeting. The activities director wants to intro the program with a clip from one of the Mission Impossible movies where a drone is used in an action packed scene. Talk about riding the hype curve...
The sun was out, the winds were light, the temperature was about 85F, it was my birthday. There was nothing else to do but discover if all the time, money, energy, planning, and hope would work out.
It was a qualified success! Qualified in that I think pitch is reversed but in the case of today's short effort, it was another event of discovery on the road to longer flights.
The good news was I did not break a prop! The casualty of the trials was a leg! Anyone out there want to report how the stock 3DR legs break? They do sell spares at the store so I suspect one or two have failed.
The leg breaking may have been encouraged by the tether arrangement. The quad was blown while the line was taught and circled into the yard while I lowered the throttle. It impacted on the leg sideways moderately hard. The ground was wet and the toe stuck in the dirt while the copter kept rotating. The break was where one might expect it, at the through hole for the cross brace. If it had been on the driveway, I suspect it would have just skidded.
From my previous blog posts you would have known that while cutting legs out with my home brew CNC mill, I made plenty of extra legs. 10 minutes on the bench later and the Arudcopter was ready to go again. Unfortunately it was time to pack up and go see the grandchildren.
The tether weight was an old lamp ballast I use for a glue weight. I didn't think the copter could drag it anywhere especially with the small 'purple' motors (3DR sourced).
While driving to Tennessee to see the kids, it occurred to me that some sort of telescope/tilt platform would be a good tool for a copter-in-adjustment. All too often I read posts of noobs like me wanting to blame the APM or code for a setup issue. I suspect some form of gimbal jig to allow a tethered hoover would confirm if a command axis is reversed.
Throttle was good with liftoff around 52% of stick. Yaw seemd correct but the tether would yaw the quad when wind blew it to the rope end.
All in all, I am pleased and it was not a bad way to spend my 54th birthday.
It was a productive weekend: MP up and running on my shop PC, aircraft firmware loaded into APM2, radio connections troubleshot and calibrated, Wow! There's my house with a graphic quad hovering over it! (I am not worried about giving away my coordinates. Come on by but call first, please.) After performing the leveling cal I even was able to watch the artificial horizon roll correctly, the compass indications were correct, and all in all it was just plain cool!
The Configuration -> Radio Calibration section of MP is great. Graphically you can see if your transmitter outputs need inverting and also if they are centered well. This is a great benefit if your transmitter does not have this feature but it is more important to the operation of the aircraft.
I hit a wall when it came to calibrating the ESCs. 3 hours of frustration and a day later, the short version of the story is: Triple check your wiring of the *output* of the APM2 if you can run the ESCs one at a time off the receiver throttle output. I messed up and had the ESC output cable on the wrong end of the header. Output 8 - 5 DO NOT drive the ESCs. I now have a gold star on the top of the cable plug and oriented to remind me of how it is supposed to be installed. The picture below shows the cable, on the right, installed incorrectly.
Tonight I succesfully performed the 'all at once' ESC calibration and ran all four motors up under APM control! Then my ESCs decided to inform me that the battery had drained sufficiently to allow them to refuse to operate. The indication was a "1-2-3" (increasing pitch) beep series followed by "1-1-1-1-1-1..." (same pitch at 0.25 sec interval). Low battery. Onto the charger it went while I do this post.
Spektrum DX6i note: Part of the troubleshooting yesterday involved figuring out why Ch 5 was following inverted to the throttle input. This was simultaneous and proportional. Ah yes, the hand in the back.. Mr. Sikorsky? Very good! You must set up your Spektrum DX6i (or what ever DX you have) in ACRO (fixed wing) mode. Somewhere this was not clearly explained to me. I suspect this is true for any of the programmable RC transmitters. If you think about it, there is no such thing as a multirotor RC transmitter mode. I suspect that soon enough the maufacturers will provide multirotor graphics to make those of us who are obsessed about that kind of thing happy. Until then, the airplane graphic will do just fine.
As mentioned in a previous post, we need some form of kill switch to make system power isolation easier than pulling a stiff connector off the battery. My right thumb is nearly raw from all the efforts. Yes I am whining but there must be a better way. A rework of my battery mount is also in order. The sticky foam being employed does not stick to itself very well. The double velcro straps work but if the foam slides, so does the battery. A multi-connector manifold for Deans, EC-60, etc connections would also be cool. That way most any battery I have could be employed. Most have Deans but in the pic above you see the EC-60. The PDB has an XT60. Connector proliferation has struck in spite of my efforts to not allow it!
In short, my soldering job seems to be good and now that the wiring is sorted out and basic functions and calibrations were performed, a maiden flight, though probably short, is very near.
This means more time with FMS and the DX6i.
After reading several blog posts and discussions about folk having startup issues with ESCs, APM2s, etc, I thought it prudent to build a simple servo tester to allow ESC checks sans APM functionality. The new issue of Make Magazine, #31 (I did a discussion post last week after the mailman delivered it) has a section on servos and their function. It included a common manual servo tester/driver.
I had everything needed to build it in my stash except a 50K pot that was less than 10 turns. A quick trip to ebay and $5 later got me 5 pots.. delivered in less than 5 days!
Why, you say, didn't I just buy a premade servo tester while I was on ebay? In general I like building things rather than consuming things. If you started with my first blog posts, you may recall that I buy where it makes sense and build when it pleases me and I have the parts on hand.
In the case of my tester, I know and understand how it works. I didn't take pictures of the scope outputs because the circuit is so well known and there are much better sites that can show you servo drive theory. Go consume them for details. ;-)
How, pray tell, did I determine the CCW, CW direction of the motors without installing the props? I ran the motor at the lowest speed adjustable with tape on the outrunner section of the motor. My finger served as the direction indicator.
Motor 1 was fine CCW. All the others required a lead swap to obtain correct rotation. This process also allowed me to run each motor up to the max my simple tester provided. Listening for bearing knock, grind or other mechanical issues that might have crept into the build was also part of the process.
One thing that is for sure, we need some type of kill switch on these machines. I haven't put much thought into it but it would be a grand safety feature for these birds.
Next up I wanted to verify the output power of the ESC to the APM2. The simple tester worked so I knew it was in the range for the circuit design but the APM2 is a little more particular than a 555 circuit. On a previous trip to the local hobby shop an Electrifly Power Match power meter had followed me home.
The power meter has Rx/Tx inputs to act as a voltmeter for those supplies, perfect for what I wanted to know. The ESC may not have an adjustable output (like Castle Creastion units) but the 6 millivolt low value should not be a problem if the ESC holds steady.
The Arducopter assembly manual, if read sequentially, led me to believe that the power to the APM2 did not require the JP1 jumper. It would not power up as shown in the assembly manual. Further reading indicated that JP1 is the default mode. I tested the APM2 with a USB cable and it powered fine. Back to the PDB lead, JP1 installed and...
hurrah! Going for the gold I added the Spektrum power input. The receiver modules lit up looking for a bind (not shown in the above pic). The Tx was in the house so I declared victory and called it a day.
Little steps add up and now the ESCs are direction correct and I can begin to integrate the APM2 software and bind the Spektrum Rxs with the Tx.
Thanks to DIY Drones, I discovered there is another Aruducopter, now flying in South Carolina. None the less, my build continues and this time the RC Rcv deck was the focus.
The documentation on the AR6210 states that the remote receiver must be at least 2 inches away from the main and perpendicular to the main receiver. To accomplish this with the cable that came with my gear, I wanted to use a stack up plate with extensions.
After some sketching and judicious work with my mini mill, razor saw, and titebond wood glue...
The idea was to provide a rigid mount for the Spektrum modules while securing the wiring.
After cutting some saddle points, drilling holes for the cable ties and installing some sticky foam pads under the Spektrum modules, I then fabricated some stack up hardware out of the aluminum hex standoff hardware from my stash.
Here's a view from above demonstrating the passage of the PDB board cabling up through the stack.
Although not 'stock' (if there is such a thing), I wanted the APM2 at the top to allow me visibility of the LEDs, easy access to the reset button, easy connection of the USB, and easy access to the SD card. The APM2 inputs are on the other side from the Spektrum receiver to allow easier management of the wiring (longer run takes up the wiring). The 90 degree connectors also allow a lower profile for the top plate.
Next to order are the signal cables to connect the APM2 to the AR6210. Initial tests will be with the AR6210 powered through the APM2 connections. There is plenty of room between the two plates for my Vex 9.6V 1000mAh pack to power the AR6210 if so desired. The AR6210 handles 3.5 to 9.6 VDC.
With the soldering on the APM2 complete (I think) it was time to move on with the stack up plates for the quad. For those who have not put their hand on an APM2, the Xacto knife with #11 blade provides some scale.
I am using aircraft plywood (it is on hand and paid for) rather than the FRP/G10 that is popular. Using ancient methods of razor saw and ruler, three stack up plates were cut and the process of making a home for the APM2 was initiated.
Some tolerance creep has set in but that is normal with a mixture of hand and machine tools. I wanted the wiring to pass up through some of the boards rather than outside the stack. This may provide a neater harness and offer some protection against impact damage.
Having a Mini Mill comes in handy on a project like this. The cable slot was a cinch to cut after penciling an outline. I used a 1/8 4 flute end mill to do the cutting. Sandpaper was used to finish the edges.
I marked the APM2 holes, drilled them, and then counter drilled with a 1/4 end mill to sink the nylon standoffs into the plywood. This reduced the length of the mounting screw needed to hold the board in place.
After turning down (with my 7 x 12 lathe) some aluminum threaded hex standoffs to clear the electrical parts on the board, I cut a plexiglass plate to cover the APM2, drilled it, and found appropriate screws to hold the lid on. The 4/40 screw heads are on the bottom of the plywood plate. They pass up through the nylon spacers, through the APM2 with the pcb held down by the turned end of the aluminum standoffs. I colored the hex end 'knobs' black with a Sharpie to add some style to the mount.
Here is a idea: Perhaps using plywood will dampen vibrations in the system? I can also employ some RTV/Silicone washers if vibration is more suspect. Frankly a proper balancing of propellors would go a long way to reducing vibration on a quadrotor.
Next task: The stack plate for the Spektrum RC gear (main and remote). I actually cut/drilled three plates prior to the APM2 final machining. I've got two blanks to go.
On second thought, maybe ordering the APM2 assembled would have been a good idea.
Nah, why let someone else have all the fun? The board is wonderfully small and has convinced me that SMD components require learning new tricks if I plan to roll my own in the future. Over 35 years of through-hole work only qualifies me to solder in the header pins.. barely. You see a very vintage grounded Ungar iron and the ESD packing on my bench acting as my base ground ("Where's my anti-static mat?")
I could not locate an order of assembly for the 'kit' version of the on-board GPS (the APM1 has one) so...
Here is what I did:
The GPS header connector was not marked with Vcc or Gnd. This implies the power and return (earth, ground) are delivered through the single pins. If I missed the markings, at least the board is mechanically intact if/when an uncontrolled impact should occur. Besides, the pictures of the pre-assembled APM2 seem to show those pins soldered from the top.
Why did I go with the kit? I wanted the 90 degree connectors for the inputs/outputs rather then the stock units. I think cable management will be neater this way. When I get APM2 in the Quad stack up, this will be confirmed or recanted.
My plan is to do bench testing of the APM2, Mission Planner, etc before even thinking about trying to get off the ground.
Last week I purchased a Hitec X1 AC Plus Multicharger and an Eflite 3S 3200mAh LiPo from my local hobby shop (previously mentioned in the first blog post). More to do is matching up connectors from the battery to the PBD on the quad. Also to make up are the stack up plates for the APM2 and RC Rcv section. Writing the Gcode for these can be time consuming but it will allow me to create spares if they are broken while learning to fly. I think I will buy interconnect cables from 3DR. We've got to keep folks employed afterall.
There are a lot of home-brew parts in this machine (no fooling, really).
I had orignially fabricated parts based on the 'A' frame but after noticing the 'B' release, I ordered replacement parts and modified mine as close as possible. The bottom plate is 1/8 aircraft plywood painted. The top was made from an FRG piece I had in a junk box.
Getting access to the PDB is now much easier and if you have an 'A' and break it, go to the 'B'.
The legs are made on my home-brew CNC Dremel router.
Using the posted 3DR drawings, I made some G-code that cloned the 3DR leg pretty close. I didn't bother with the nice radius at the 'foot' end but may tinker with the code later. The harvested circuit board material found new life rather than being tossed in the landfill to decay over a thousand years. This way I get to break it in spectacular fashion!
I used 6-32 screws and remachined some aluminum hex standoffs I had for the leg hardware. I let the CNC router crank out two complete sets of legs as I suspect a few will get broken while I earn my quad wings.
Using what I have in my shop/garage and buying significant parts from 3DR has been my approach.
Things left to do/make are:
More to come!
April 14, 2012
I've been assembling the PBD, ESC and motor connectors.
I went with the XT60 for the battery side rather than the Deans.
After routing the motor wiring as mentioned previously, I added another layer of heat shrink to the wiring to provide another level of anti-chaffing.
For those of you interested in the actual hole pattern on the arm...
As this is my trainer quad, as mentioned before, I think the next arm will have radiused corners out past the motor. This will reduce impact edges and give the arm a more finished look I think.
Here is one of the arms with the extra heat shrink at the motor, the ESC with all connectors zip-tied in place.
I took the Arducopter, prior to mounting the just shown wiring updates, to one of the local shops in Greenville, SC, The Great Escape. Keith is the resident heli-nut and we discussed the need for me to spend time with a simulator. Real Flight 6 Heli now has a quadrotor in the selection. The in-store demo unit had me hovering and breaking props in between reset button presses. It looks like a great product and at rev 6, it seems that it won't be going away anytime soon.
Keith inquired about the PDB and had not heard of 3DR. A quick trip on one of the store's PCs to the DIYDrones Store and he was in love with the Hex copter. I tried to explain the APM and its open source development. He was accustomed to a single threaded application (dumb controllers) rather than a 'smart' controller like APM.
We had a good visit for about an hour or so and I promised to return when the Arducopter was getting closer to flying.
Before I get the funds for the APM order, I may build a servo 'stimulator' and check the motor directions. Anyone ever try that before bolting in an APM?
May 19, 2012
Checklist items acquired for the quad:
Still building funds for the APM2 purchase. I gathered parts for the servo stimulator and need to get that sub project going. I may just breadboard it and then used one of my favorite programming languages - solder.
