12 Mar 2013, 5:38am
Uncategorized
by

Comments Off

Vacation Engineering

For my day job, I help design CNC machines. Sometimes that looks like running around wearing a lot of different hats, and I don’t get to do much actual design, or actual engineering. That’s where Vacation Engineering comes in. Flying machines make for great vacation engineering projects. They have a nice beginning, and a clear and concise end. Usually that end is punctuated by a good solid impact with the ground.

Recently, I’ve been working on refining my folding tri-copter design. People have built folding tri-copters before, most notably FPVManuals, which is where I first heard of the concept. It’s an excellent design, and he sells kits. For my own designs, I started out building them from ABS, instead of acetal. It’s a lot lighter, has better impact resistance, and unfortunately suffers from one major, major drawback. When you cut it with a laser it releases hydrogen cyanide :(

Still, with extreme ventilation it’s possible, and so the first machine I built was made out of white ABS. It flew really well, until it eventually met its untimely demise atop the Eureka sand dunes in Death Valley.

A soft landing.

A soft landing.

Rev2 used a Quadrino controller, and suffered from a major design flaw. There was just too much mass in the center of the craft, relative to the arm length and motor sizes. The control loops just weren’t tunable. I could get the craft to stabilize, but once it started moving it would rapidly lose stability and fall out of the sky like a rock. I had switched to acetal (aka Delrin) at this point, so the extra frame mass was mostly coming from the plastic plates.

MiniTri_R2

After learning that lesson, I took Rev3 in a completely different direction. I had spent hours and hours trying to tune the Quadrino’s PID loops from the previous version. A process which involved connecting a cable, setting the new values, disconnecting, and retrying with the new settings. It was obnoxious. Around this time HK released the excellent KK2 flight controller board, which had a revolutionary new feature: onboard setup and tuning via buttons and an LCD screen.

So I ordered one and set about designing Rev3 for the KK2 board. It came out really well. Mass was considerably lower and centrally located, and so the loop tuning only took a couple of test flights to get up and running. I was still using 0.5″ aluminum C-channel arms at this point, and they don’t offer a lot of stiffness. Eventually, after a few hard landings they would get bent and introduce pretty agressive Yaw drift from geometry errors. The restraining tabs from the folding mechanism where also too lightweight and eventually I bent and cracked this frame.

MiniTri_R3

For the fourth revision I kept most of the design changes I made for R3, however, I swapped out the expensive aluminum arms for cheap pine wood ones. These proved to be considerably more resilient than the aluminum arms. The wood arms are much easier to make than metal arms. They only require two holes to be drilled with a drill press, after being cut to length. It took a long time before I broke an arm, and it broke in exactly the right manner, leaving the rest of the frame and electronics intact.

The ESC/Battery carrier plate has also proved to make the rest of the wiring neater. This keeps the ESC wires out of pinch points, a problem I had with earlier revs where the ESCs hung out the side.

MiniTri R4

Next up in the vacation engineering adventures will be a two axis stabilization gimbal for the GoPro up front. I’d also like to revise the tilt-tail design. It’s pretty heavy and reduces agility from the extra mass.

Then I plan on finding a beach to fly it on, for an actual vacation.

2 Jan 2013, 9:44pm
Uncategorized
by

1 comment

The Other 1%

Recently, I was giving a last minute impromptu talk on the rise of ubiquitous CNC machines in the home at an unconference up in Seattle. The event was called CyborgCamp, and was loosely about the way humans augment themselves with technology. The highlight for me was a talk about a fellow who had turned himself into a publicly traded human. Corporatism and the hive-mind driven to one logical end conclusion. It was fun.

Sometimes I like having opinions in public. The title of my talk was, “The Coming Suburban Manufacturing Center.” The central thesis, which I’ve written about here before, was that there is a missing piece in 3D printer/Laser cutter/Mill holy trifecta of desktop DIY machines. That’s the CAD/CAM software needed to drive them. In the coming years your ability to design the world around you will be the core skill which keeps you from becoming a factory robot.

In the Q&A someone asked me this question,

“but Mike, once everyone has 3D printers and Laser cutters in their home, won’t they just print out shit they downloaded from the internet? What do they need CAD software for?”

In all likelihood this is what most people will do. 1%* of people will make something novel and new. 10% will iterate on the design patterns and create improved variations (this is where I like to hang out), and the remaining 99.99999% will “just download shit from the internet.” He’s probably right, and I don’t have a good solution to that problem, but there’s another way to think about this brave new world.

we'll always have Paris.

we’ll always have Paris.

I think the goal is to increase the absolute total number of people with access to this technology, not to move the percentage of people with access who use it to do something novel. For one, I think novelty is way, way over rated. Our society places a huge value on the lone inventor, that genius who comes up with a new idea that changes the face of the world. Probably because those events are so phenomenally rare.

I feel like the execution of an idea is more important. If you have an idea, but can’t deliver, at best you serve as a warning to others. Worse still, you can run the risk of having this idea in the Plains of Poor Execution, where you do it just poorly enough to demotivate others from doing it well.

The reason increasing the number of people with access to technology is important, is that for innovation to move quickly, best practice usage patterns for that technology need to hit as many people as possible. If there’s a very small number of people who will stumble across the Truly Original Idea, they way we get to a world where we find more of these innovations is to run as many parallel experiments as possible.

Where does innovation come from? Some people think it comes from play, and play comes from undirected access to resources. That “undirected” part is important and ties directly back to the original need for universal access to an ability to design our world around us. Locked up in ivory towers, behind a prohibitively expensive cost-of-entry, these tools end up serving the rigid motivations of the industries willing to invest in the up-front capital expense.

To put it another way, your boss at Lockheed-Martin is unlikely to be happy with you designing your art project on the $40,000/seat CAD packages you use to design strategic missile defense systems during the day. Undirected access to creative tools creates an explosive expansion in creativity. The Internet being the best example of this phenomenon. Access to increasingly easier to use CAD/CAM software has the potential to completely reshape our world, with a potential impact as important as the Internet.

what could go wrong?

now available online.

Democratization of design tools also has some drawbacks. It puts a lot of noise in the signal, and in the coming suburban manufacturing center we can expect to see all kinds boogymen pop up. Intellectual “property” theft. Invasions of privacy. Weapons. I can see a world not far from now where owning a 3D printer could require a license & logs. The hoopla over 3D printed weapons has a lot of policy makers panties in a knot, but the really strange scenarios are yet to come.

Which brings us to the Other 1%: the designers of the modern world. There is an immense privilege in being able to create ones world around oneself, instead of having it created for you. There’s the obvious economic opportunities it creates, but the process of design opens doors of all of other kinds. The process itself generates more opportunity to take that experience and use it solve problems in other domains. We’re going to see more and more conversations about who should have access to manufacturing technology, and what form it should take. It’s going to change our laws, and our society.



when i was your age…

What is interesting to me, is that it is becoming increasing useful to frame access to design tools, and the knowledge of how to use them, as a form of privilege. Much in the way that we discuss gender, class, and race privilege. Those that have it will be designing the world for everyone else who does not. The thing about this technological privilege that’s different than the others though, is that I hope it’s going to be a lot easier to improve.

* In reality it will be much, much smaller than that…

28 Dec 2012, 1:22am
Uncategorized
by

Comments Off

Someplace New

A few weeks ago I got a shiny new Adafruit FLORA kit in the mail, it’s a lovely little board, and a lot of thought and care has gone into its design. Here’s what came in the box:

Some sewing required.

some sewing required.

That’s one GPS input, and bunch of LED outputs, prototyping cable, and a controller board. I was most excited about the LED modules. They solve a bunch of the problems associated with attaching LEDs to garments and getting them to produce some useful color in a controllable fashion.

I’ve been toying around with wearables for a while, and it has always suffered from a utility & UX problem. Other than glowing for the sake of glowing (which can be quite beautiful), there’s a short number of projects that meet nicely at the intersection of aesthetics & function. Combining a shirt with a computer has a tendency to produce a slightly uncomfortable shirt and an unreliable computer.

It’s not to say there isn’t really cool and exciting work being done, and some of it can be found documented on Syuzi Pakhchyan’s Fashioning Technology blog. When I think about wearables technology, it roughly breaks down for me into:

  • Blinking Lights.
  • Location tracking.
  • Ambient sensing.
  • Materials research.
  • Fabrication methods.

Most of the things I find to be really interesting tend to lean more into the ambient sensors category, largely because input technologies tend to lag output technologies in resolution/bandwidth/cost, and so they get less play time. One old project I put together was a top hat with a magnetic hal sensor, it would change color depending on which way one was pointed. It was pretty useless, most of what I learned from the experiment was that people really don’t like staring at super-bright color changing LED when trying to talk to you. Eventually I covered the LED with a translucent toy rubber frog, the magic hat was much improved.

I digress.

As the FLORA was a gift from Adafruit, I wanted to see if I could find something to do with it that would show the system off. Having recently lost my sewing lab, and living in a tiny apartment, it also turned into an experiment into what I could make with minimal resources. No space to pattern out a jacket from scratch.

The first idea I had was to put a couple of color changers under the collar of a dress shirt. San Francisco has recently seen the arrival of urban clothing retailer UNIQLO, which is like a Japanese version of the GAP. It’s the perfect art supply store for clothing moders and hackers. We braved the pre-holiday madness, but where unable to find a suitable dress shirt. At least not one I would wear in public. Dress shirts also suffer from the problem of needing regular cleaning, a part of the fashion tech lifecycle that’s a little rough around the edges. Instead I picked up a nice black cotton blazer on sale for $39, a price at which I could afford to make mistakes without crying too hard. In addition, cotton is easy to hand sew, and very forgiving if one needs to back-out stitches.

raw materials.

raw materials.

First step was testing the setup. Using the included aligator clip jump clips, it just takes a few minutes to get the board wired up. I downloaded the Adafruit Arduino app, updated the GPS libraries and LED libraries from the Adafruit github repo, and ran the test examples. GPS lock and blinkin’ lights achieved!

Sewing was a little harder. I’ve never had much luck stitching threads onto contact pads. Conductive thread is better thought of as conductive resister, and as such it’s reasonable at handling low speed signals, that don’t require a great deal signal integrity. The stainless thread that comes with the FLORA is the best I’ve used to date, but it still doesn’t knot very well. This is problematic if you want you connections to stay put as you’re moving around.

First Attempt

First Attempt

Eventually, after a few short minutes some of the knots I’d put in had come loose and the GPS started dropping packets and power cycling. The terminated connections are also pretty ugly. Little loops of stainless thread. I wanted something a little tidier. I’ve used silver bead crimps in the past for creating reliable connections on surface mount LEDs with great success. Maybe they would work for this project?

The process is pretty simple. Thread a crimp onto the needle and crimp at the far end. Thread through the pad, until the crimp rests flat against the pad. Sew to the other end, and add the other crimp. Fold over onto the pad, solder, and trim. Like so…

Neat and tidy.

neat and tidy.

With that sorted, time to make it was time to make the jacket do something. I decided I would make blazer jacket with a boutonnière that would glow brighter the faster I went. One output, and one input. There’s a lot of information you can get out of a GPS: heading, speed altitude, absolute position, time, and so on. The code is really simple:

#include <Adafruit_FloraPixel.h>
Adafruit_FloraPixel strip = Adafruit_FloraPixel(2);

#include <Adafruit_GPS.h>
#include <SoftwareSerial.h>
Adafruit_GPS GPS(&Serial1);

void setup() {
  
  // debug out
  Serial.begin(115200);
  Serial.println("Go Faster.");
  
  // 9600 NMEA is the default baud rate for Adafruit MTK GPS's- some use 4800
  GPS.begin(9600);
  GPS.sendCommand(PMTK_SET_NMEA_OUTPUT_RMCGGA);
  GPS.sendCommand(PMTK_SET_NMEA_UPDATE_5HZ);
  
  // init the color pixel
  strip.begin();
  strip.setPixelColor(0, Color(0,16,0));
  strip.show();
  
  delay(1000);
}


uint32_t timer = millis();
void loop()
{  
  // if millis() or timer wraps around, we'll just reset it
  if (timer > millis()) timer = millis();
  
  // read the GPS
  char c = GPS.read();
  if( GPS.newNMEAreceived() )
    if( GPS.parse(GPS.lastNMEA()) )
      {}
  
  // update the brightness.
  if( millis() - timer > 500 )
  {
    if (GPS.fix)
    {
      int n = GPS.satellites;
      RGBPixel c = Color(8,0,8);
      if( n < 5 )
        c = Color(0,0,1);
      strip.setPixelColor(0, c );
      
      float mph = GPS.speed * 1.15078;
      n = mph * 4;
      if( mph > 2 )
        strip.setPixelColor(0, Color(n,n,n) );
    }
    else
      strip.setPixelColor(0, Color(1,0,0) );
    strip.show();
  }
}

This works pretty well, and the brightness change between a standstill, walking, and biking is noticeable. The FLORA is small enough that I can hide the GPS, LED, and controller underneath the lapel of the jacket. Until I start moving nothing is noticeable. If I set the threshold to enable the lights above 5mph and add a 15sec fade out timer it turns the jacket into an automatic jogging/bike light, I just need to add shoulder tail lights.

Nothing to see here.

Nothing to see here.

I’ve been thinking about other experiments to do with this jacket. The speedometer is fun, but it wears the batteries down pretty quickly. I’d like to make a jacket that buzzes when I’ve been someplace new. That sort of persistance is difficult to maintain without a lot of support hardware, but I like the idea of have a little reminder to seek out breaks in my daily routine.

LEDs are probably the wrong indicator, a buzzer is better for this sort of thing. Haptic vibration motors are much better at conveying information in clothing. They can be very low power, and generally have a higher environmental contrast ratio than optical systems. That is, when something buzzes against your skin, you notice. As we generally don’t go around staring intently at ourselves, optical systems aren’t as good.

A small haptic output device is one addition to the FLORA platform I’d like to see. Until then, there’s the LilyPad vibe motor that will do the job. It’s a little on the large side, but if you don’t need high resolution or variable intensity it will probably work.

22 Jun 2012, 6:20pm
Uncategorized
by

Comments Off

Only Human

I found this quote today. It’s from section 1.4 The Design of a Design Engineer in Alexander H. Slocum’s Precision Machine Design:

“When the author first decided to pursue a career in design, he was immediately humbled when he really took a close look at things as complex as automobiles, CNC machines, spaceships, and tall buildings. Trying to comprehend how these complex things where designed and built gave him an appreciation for the capability of the human mind to break down even the most complex projects into workable tasks. He then realized that he was also a human and therefore he must also have this same ability.”

30 Apr 2012, 5:30pm
Uncategorized
by

1 comment

In Othernews

After two years of giant art projects, running away to join the circus, too much minecraft, and the occasional robot contract, I’ve re-entered the world of gainful employment. I’m working at a little independant research lab situated in a former pipe organ factory, called Otherlab.

It’s an amazingly quirky little spot, doing everything from advanced robotics research, to electric vehicles, solar energy and education. I’m working on the education part. We’re working on building a platform to lower the cost and increase the accessibility of science, technology, engineering and math education. As a self-taught engineer, this is a topic very near and dear to my heart.

The project is part of DARPA’s educational initiative, MENTOR. We have three goals. First, to build an extremely low cost CNC machine that can cut out cardboard patterns. Second, a set of projects that kids, adults, and the general public can build using this machine. Third, a platform where they can document their experience, what they learned along the way, and share it with other people in a way that allows the knowledge base to collective advance and grow.

It’s got some lofty goals, and we have a very short amount of time to do it in. This is probably why I missed an internet debate about my project that flared up recently. It started with the following post from Noisebridge co-founder Mitch Altman:

“It’s official. I’m greatly saddened that I won’t be able to help at this year’s US Maker Faires after they applied for and accepted a grant from DARPA. I look forward to working and playing at Maker Faire again, after they are no longer associated with DARPA.”

He goes on later to say,

“My main reason for making my decision public is to encourage public discussion on this important topic. I’m glad it’s working. We really need to consciously make choices on what we do for money. In my mind, it is not about the money. My hope is that we do what we do because we are exploring and doing what we love (whatever that means to you!).”

Sure, I suppose we can spend some time discussing this. It’s a sentiment I’ve seen pop up in a few places, not just around government attention, but corporate attention as well. This is how I personally feel about it:

Over the last decade, I’ve watched the Maker community slowly growing into something really wonderful. I’ve watched friends start hackerspaces, build open source hardware businesses, and countless folks go out into the world and make amazing things. The rest of society has started to wake up and take notice. From big business, to the government, to hollywood: everyone wants to know what we’re about. They want in because frankly, I think we’re winning.

Maker culture is spreading, and there are a lot of newcomers. I think its only natural that many of its early leaders would feel nervous about all this new attention. After all, we built this new world up because the old one didn’t work for us, and we don’t want to see it ruined. Not an unreasonable fear, but rather than jealously defending the tree fort, I think we should be inviting them in.

It’s going to be a bumpy ride at times. Not everyone is going get our ideals, and our values. We’re going to have some weird conversations, like when we explain to big business how giving away all their intellectual property creates more market opportunity, not less. However, these conversations are going to happen, weather we want them to or not, and the participation culture should include all of society, not just the San Francisco hackers with funky dyed hair*.

This is why I think working on the MENTOR project is awesome. I like its goals: improve STEM education in America with open technology. (I even hear we get bonus points if it improves it elsewhere…) We’re trying to bring the DIY culture to the classroom.

I’m not afraid of big business, or our government, or the entertainment industry coming in and “ruining” our culture. I think our ideals are more resilient than that. I’m afraid of missing an opportunity to change theirs.

Who knows, I might even learn something from them as well. It’s what sharing ideas is all about.

*It’s currently red, in case you where wondering.

How To Build a Cardboard Quadcopter

Keeping with our recent all-multirotor all-the-time theme, it’s time for another how-to post! Plans are afoot, and scheming has been schemed. The flying robot skeletons have been piling up in a corner of the workshop, and after several revisions we’ve narrowed down the design to something worth sharing.

"Eventually, we'll get it right."

Maybe you want to build your own? Maybe you want to take this design and mod it for agility, weight, or style. Awesome. First, here’s the base pattern:

PaperQuadRev5BPattern.pdf
(updated on 04/15/2012)

Getting Started

First off, you’ll need some tools:

  • CNC laser cutter. In theory, you could cut these parts out with an x-acto knife, which is madness. You’ll want to borrow a laser cutter. Honestly, you should just buy one. They’re the absolute best thing in the world, and the prices are dropping very fast. Check out Hurricane Laser, for example. Or TechShop.
  • Scissors, for cutting tape.
  • Soldering iron, and solder.
  • A can of Super77 spray glue.
  • 60degree hole chamfer. Handheld is fine.

You’ll need the following build materials. For my examples, I use cardboard sheeting from ULINE.

  • Several sheets of 4mm cardboard. The thickness matters, if you change the thickness, make sure you update the tab cutouts to match. They’re 3x the thickness, or 12mm.
  • Brown paper packing tape for sealing the edges. The clear stuff doesn’t stick very well. You can also use fiber reinforced tape.
  • 4×4″x1/8″ black ABS plastic sheet. You can also use heavy card stock, sheet metal, acrylic, or aluminum bar stock.
  • No. 127 Black ESD or similar. 7”x1/8″
  • One 14oz ZipLock plastic container, or other lightweight 5″ diameter bowl.
  • Double sided copper clad PCB board, you’ll need about a 0.5×0.5″ square piece.
  • 4 paperclips.

For electronic components, you’ll need the following:

  • 4ea 22mm brushless outrunner motors. I’ve used both Cobra 1300kV and DiyDrones 850kV motors.
  • 4ea matching prop adapters for your motors and propellers.
  • 4ea regular propellers. GWS 8×3, GemFan 10×45, etc. Yes, 4ea. You’ll want extras, lots of extras. You’ll break a lot of props at first.
  • 4ea reverse propellers.
  • 4ea ESC controllers for your motors, with an on board BEC. I use 20A NextLevel controllers.
  • 20mm heatshrink, for the covering the copper clad power board. Electrical tape works too.
  • 6mm heatshink for covering connectors and wires.
  • 0.1″ spacing jumper wires, female socket. For the battery power sense line.
  • Controller board. I use the Quadrino Zoom.
  • Cable assembly for Quadrino Zoom.
  • Spread spectrum 2.4ghz transmitter and receiver. 6 channel or better. Spektrum DX6i, etc. There are 4 control channels, and 2 mode channels. You’ll need another two channels if you want to add head tracking later.
  • 2-4ea, 2000-1300mAh 3S LiPo battery. Trust me, you’ll want more than one. Your motors must match the battery voltage. I use Turnigy batteries.
  • Lipo battery charger.
  • Battery connector plug and wires. I use XT60 plugs.
  • Sparkfun Blutooth module, if you want wireless telemetry. Totally optional.
  • Nylon mesh wire sleeve. I use this to protect the motor leads from prop strikes. Also optional.

(GoogleDocs spreadsheet.)

It’s a lot of parts and pieces, it’s true. Depending on where you source things from, and how fast your shipping times are, it can take up to a month for all the parts and pieces to arrive. HobbyKing has notoriously long wait times, for example. If you care about customer service and speed, order domestic. I recommend Innov8tive Designs.

Got all your parts and pieces? Great! Let’s get started…

(**Hey, what’s with those holes in the picture? How come they’re not in the plans? Turns out the tend to cause frame failure for really hard landings, so I took ‘em out. Amazingly, it still flew after one of the arms bent…)

24 Mar 2012, 1:45am
robotics:
by

Comments Off

Cardboard Tricopter Build Plans

Joachim here,

This tricopter frame design is decently ridged, it’s not extremely crash resistant, but it does fine with a few hard landings. This is the first flying revision, so there is plenty of room for design improvements. Improve and share! Available under a creative commons ShareAlike-NonComm-Attrib license.

Source files here: 24cmTrV2.zip

You’ll also need a few build materials:

  • Lasers, or a lot of time and a sharp knife.
  • Glue: less is more!
  • Itoya- O’Glue, school glue, etc.. some kind of water based glue
  • Hot melt glue – hot glue gun
  • CA glue – super glue
  • 3.2mm rod, carbon fiber, fiberglass, wood, or a glue-able plastic

Arms are each made from 4 laminations of 3mm cardboard. To better resist bending, cut the outer two arm laminations parallel to the corrugation, and the inner two perpendicular.

Cut 5 base plates and 1 top plate. Three of the base plates will go on the bottom part of the frame, and the other two will combine with the top plate to make the upper part. For maximum durability, rotate each plate lamination 120 degrees so that the corrugations criss-cross when you glue them. You may need to adjust the motor mounts and servo profile in the tail arm to match your parts.

Total cut list:

  • 4 arms parallel to corrugation
  • 4 arms perpendicular to corrugations
  • 2 tail arms parallel to corrugation
  • 2 tail arms perpendicular to corrugations
  • 5 base plates
  • 1 top plate
  • 1 set servo retainers – 1.4mm cardstock
  • 2 motor mounts – 1.4mm cardstock
  • 1 tail assembly top and bottom – 1.4mm cardstock

For the laminations use a moderate amount of water based glue – Itoya-O’Glue is nice. You could use spray adhesive too, but it’s $18/can.

Press:
Get two sheets of something really flat, i.e. some scrap acrylic sheet you have laying around. Sandwich your newly glued arms and plates between two of these flat sheets and put a good number of books and heavy things on top (~15kg). This will press the glue into any voids and keep your structural members straight as they dry. If you used the water-based glue, leave the arms to dry for about 24hrs, no peeking!

Frame:
Now that you’ve waited 24hrs for your parts to dry, retrieve them! As long as you were somewhat careful when you aligned the laminations, you should be able dry assemble your tricopter frame plates and arms. I start gluing the base plate and arms together with about 3mm gap between them- I squirt some hot glue into that gap and press the parts together. Work fast, hot glue works a lot better when it is hot!

Motor mounts:
Adjust the mounts to fit your motors. Mount your motors to the motor mounts, glue the mounts to the arms with hot melt glue.

Tail yaw assembly, the hard part:
Cut the rod to about 4.5cm or so and slide on your hinge parts, rotating them 180 degrees from each other. The hinge elements should rotate relatively easily but not be loose, or really stiff. Line up the rod flush with the first top tail plate hinge element. Line up your hinge elements with the tail hinge plate top and bottom. Make sure all the hinge elements are straight. Use CA to carefully glue hinge elements to the top and bottom, don’t get glue on the rod! Double check that everything is lined up and let the glue fully set. Now that the glue is set, double check that the rod is aligned with the first top plate hinge element. Carefully glue *only* the top hinge elements to the rod. Trim your servo horn so that its splined hub can fit on the front top hinge element co-axial with the rod, it might help if you sand away any surface features from the servo horn. Double check your alignment and glue the servo horn to the front plate. Allow the glue to set.

Make sure that the servo is centered by connecting it to a powered neutral RX channel.

Carefully partially test fit the hinge on the servo, don’t push it on all the way, I doubt it would survive removal from a snug shaft. Make sure that your hinge is co-axial with the servo splined shaft. You might need to add a shim to the bottom of the hinge or trim the arm a bit to make sure the hinge and servo are co-axial. Carefully fit the hinge hub onto the shaft. I use hot melt glue to glue hinge bottom to the tail arm.

Attach your electronics and go flying!

Additional Resources
Some tricopter fundamentals by David Windestål – http://www.rcexplorer.se

  • http://rcexplorer.se/Educational/kkguide/kkguide/tri.html
  • http://www.rcexplorer.se/projects/tricopterv25/tricopterv25.html
  • http://www.rcexplorer.se/Educational/HKKK/HKKK.html

Joachimp’s parts:

Thing

weight(g)

quan

total weight(g)

sub price

price

Notes

Links
Orange 6 chan RX 9.9 1 9.9 5.99 5.99 de-case, and use heat shrink to save weight HobbyKing
servo metalGear 14.5 1 14.5 4.67 4.67 HobbyKing
servo Plastic 9.9 0 0 plastic might work.
kk-board 14.6 1 14.6 14.99 14.99 You will also need a programmer to reflash this with the tricopter firmware. Most any iscp 6 pin will do. HobbyKing
esc 9.8 3 29.4 9.47 28.41 Maybe buy an extra HobbyKing
motor + hardware 20 3 60 10 30 Get at least one extra HobbyKing
5030Prop (ccw) 1.5 6 9 1 6 Get a few extra, especially if you don't have experence flying dynamically unstable rotor craft, ie, collective pitch helicopters HobbyKing
male-male JR 1.8 4 7.2 1 4 HobbyKing
tur 1300 123.2 1 123.2 10 10 Order from domestic HK warehouse, need at least 25C rate, 1000mAh – 1600mAh HobbyKing
EstAirframe3ply 50 1 0
Actual4plyFrame 60 1 60 1 1 standard corrugated cardboard, nominal thickness 3mm, density 166.7 kg/m^3 (50mg/cm^2 – one 3mm sheet)
Frame assembly structural glue 5 1 5 0 Low-mid temp hot melt glue
Composit layer glue 0 Itoya- O'Glue, might switch to contact adhesive, $18
CA – Glue 0 Servo retainer/ tail tilt hinge assembly glue
0
0
0
0
HK EMS shipping 1 30 30
Total est Weight 332.8 Total Price($) 135.06
Actual Weight 357

Cardboard TriCopter

Hot damn!

My friend Joachim P., taking some inspiration from the cardboard quad, decided to build a paper tri-copter. Using a pretty ingenious tail tilt mount, his Tri-copter comes in at 357g fully loaded. It also costs around 130$ (sans transmitter.)

Of course, he’s using a gyro only board (the KKmicrocopter controller), so one could probably get a lot more stability with 6DOF or 9DOF board, but I’m impressed none the less.

UPDATE: Build plans are are in the next post. Thank’s Joachim!

7 Mar 2012, 6:38am
robotics Uncategorized:
by

Comments Off

Cardboard Quadcopter

I finished another frame this afternoon. Now that I’ve made a few of these, the turn around time is getting shorter.

A new set of shoes.

This time with rubber-band shock landing gear, and card-stock motor mounts. They work better than the old aluminum ones from the previous frame. A friend with a bit more flying experience than I came over to help me grab this video.

The paper shocks aren’t holding up very well, but I think I can fix that.

Cardboard. It’s awesome.

Update: We took it outside and got some test video, this little guy really performs!

6 Mar 2012, 8:16pm
robotics Uncategorized:
by

Comments Off

Paper Robots, Part 4

It took a few round, and I went down a few dead ends, but today I finally managed to make a flying paper robot. Originally, I started out with a flying sphere design copied wholesale from the JDM Flying Sphere. Eventually I figured out that I didn’t know the first damn thing about making a flying robot and that it would probably make a bit of sense to try and build one that had been successfully flown by more than one other person working for the Japanese military.

So, I decided to build a quadcopter. A few people have built those, and it looked like a simpler problem.

The hardest part about getting started with quadcopters is choosing which of the half-dozen or so control platforms best describes you as a quadcopter enthusiast. I settled on the ArduPilot Mega v2. Then I settled on the MultiWii based Quadrino. Both are perfectly capable of loitering around like a lazy robot, but the Quadrino has a certain simplicity and easy-of-use that I found attractive, so I’ve been using that one the most.

Too big to fail?

As I had a few 750W motors lying around from the flying sphere experiments I decided to build my first quad out of those. This created a few unexpected problems, and a few very dangerous close calls. With 3kW of motor connected to the frame it was very much a robot, in the kill all humans sense of the word. While I did manage to make it hover, I eventually learned my lesson and decided to go with something a little more petite.

It seems that the point of all these paper robot exercises has been to try and find interesting design patterns that one can use to build cheap, reproducible robots with. With that in mind, the hard part about building a paper quadcopter frame was going to be getting it rigid enough to fly with some semblance of control.

Folded triangle failure.

I started with folded up triangle beams, as I had been using these to make legs for the walking robots earlier. Unfortunately, they proved to be difficult to anchor in a cross configuration. I could get one beam rigid, but the other would be split in two. The frame was floppy, and had a very wide profile against the prop downwash, and was a fantastic failure.

After that, I abandon triangles. I decided to try and build laminated cardboard beams in the hopes that they would be rigid enough to make a frame. For some reason I was still hung up on folding, and went with a triangular folded stiffener. It too was a dismal failure. Eventually it became clear, that I was going to have to find some way to make the arms cross each other at the center, and to find some other way of attaching the stiffeners.

In retrospect I probably should have started with slotted construction from the beginning, but sometimes you just have to do things the wrong way first. Maybe it makes for a better story. Maybe it makes figuring out the right way that much more enjoyable once you pull your head out of the… bushes.

Closer...

Hot off the laser, I slotted the new frame together. Already it was considerably stiffer than any of my previous attempts. By gluing the layers together, I could make the frame stiffer still. The final piece in the puzzle was when I remembered a bit about applying polyurethane to paper my friend Pete told me about when I first showed him my walking robots. After applying kraft tape to strengthen the edges of the cardboard, I sprayed the frame down 3-4 times with an oil based polyurethane wood finish. At 52 grams, the final frame was incredibly light, water proof, and very, very rigid. Surprisingly so!

Stronger, faster, lighter.

Impatient for my HobbyKing order to arrive, I purchased a set of 2213/34 Cobra motors from Innov8tive Designs, (highly recommended. Thanks again for the advice!), and set about integrating the electronics. This involved finding a way to attach 4 motor controllers, a radio, battery, and the control board onto the paper frame. It needed to be done in a way that wouldn’t compromise frame integrity, be easily serviceable, and survive multiple crash landings from operator and software error.

By notching the stiffener plates I found a novel way to use large black rubber bands to secure various elements to the frame. They have proven to be very versatile in holding ESCs, cables, and even heavy 4S battery packs to the underside of the frame. The 1.75 cup ZipLock plastic container that acts as the crash dome is even secured with rubber bands.

(Photo by Audrey Penven)

You got to get up to get down.

Without the battery, this little guy weighs 600 grams and pushes approximately 2400. With the hulking 4S lipo pack installed it comes in just under 900 grams and takes off at about 1/3 throttle. As the motors are small enough, I can fly indoors. The motor mounts where the only part where I resorted to using sheet metal, but I’m fairly confident they can be replaced with a heavy card stock. I can probably knock another 50-100 grams off the frame by replacing the cable harness as well.

…but that’s for another day. Now, I must go outside and fly.

Update:
If you’d like to make your own, here are the flat patterns. FlyingPaper.pdf