Driving BB-8: More Than One Way To Move This Bot

June 24, 2016 by Steven Dufresne 30 Comments

BB-8 is the much loved new droid introduced in the 2016 movie Star Wars: The Force Awakens, though in my case from the very first trailer released in 2014 I liked it for the interesting engineering problems it posed. How would you make a robot that’s a ball that rolls along, but with a head that stays on top while the ball rolls under it?

BB-8 in 1st Star Wars: The Force Awakens trailer

Hamster in hamster wheel

To make the ball roll, the answer most people found obvious at first was to use the analogy of a hamster wheel. The hamster running inside makes the wheel turn. In the BB-8 building world, which is quite large, the drive mechanism has come to be called a hamster drive, or just a hamster.

For the head, it seemed obvious that there would be magnets inside the ball, perhaps held in place near the top of the ball by a post extending up from the hamster. Corresponding magnets in attraction would then be attached to the underside of the head, and balls (also mounted under the head) would keep the head moving smoothly over the ball.

The magnet approach for the head has turned out to be the method used by all BB-8 builders that I’ve seen. However, the hamster has turned out to be only one of multiple solutions. Since the original debut many different methods have been used in builds and we’re going to have a lot of fun looking at each separate approach. It’s almost like revealing a magic trick; but really it’s all just clever engineering.

Note that for the actual movie, a combination of 7 or 8 props and CGI were used. The official working BB-8s that are shown at various promotional events were built after the movie was made and as of this writing, few details of their construction have been released. One notable detail, however, is that they aren’t using hamster drives.

Below are details of all the different BB-8 drive systems I’ve seen so far that have been built along with how they work.

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HobbyKing Cheetah: Building Running Robots From Hobby Motors

June 24, 2016 by Gerrit Coetzee 15 Comments

[Ben Katz] is building a running robot from hobby level brushless motors, all on his blog under the tag, “HobbyKing Cheetah.”

One of the features of fancy modern industrial motor and controller sets is the ability for the motor to act as a mass-spring-damper. For example, let’s say you want a robot to hold an egg. You could have it move to the closed position, but tell the controller you only want to use so much force to do it. It will hold the egg as if there was a spring at its joint.

Another way you could use this is in the application of a robot leg. You tell the controller what kind of spring and shock absorber (damper) combination it is and it will behave as if those parts have been added to the mechanism. This is important if you want a mechanical leg to behave like a biological leg.

[Ben] had worked on a more formal project which used some very expensive geared motors to build a little running robot. It looks absolutely ridiculous, as you can see in the following video, but it gives an idea of where he’s going with this line of research. He wanted to see if he could replace all those giant geared motors with the cheap and ubiquitous high performance brushless DC motors for sale now. Especially given his experience with them.

So far he’s done a very impressive amount of work. He’s built a control board. He’s characterized different motors for the application. He’s written a lot of cool software; he can even change the stiffness and damping settings on the fly. He has a single leg that can jump. It’s cool. He’s taking a hiatus from the project, but he’ll be right back at it soon. We’re excited for the updates!

How To Keep An Unruly Dryer In Line

June 24, 2016 by James Hobson 29 Comments

If necessity is the mother of invention, then inconvenience is its frustrating co-conspirator. Faced with a finicky dryer that would shut down mid-cycle with a barely audible beep if its load was uneven (leaving a soggy mass of laundry), [the0ry] decided to add the dryer to the Internet of Things so it could send them an email whenever it shut itself down.

After opening a thinger.io account, adding the soon-to-be device, and setting up the email notification process, [the0ry] combined the ESP8266 Development Board, a photosensitive resistor, and a 5V power supply on a mini breadboard. All that was left was to mount it on the dryer and direct the LDR (light-dependent resistor) to the machine’s door lock LED to trigger an email when it turned off — indicating the cycle had finished or terminated prematurely. A little tape ensured the LDR would only be tripped by the desired light source.

If you’re an apartment-dweller have WiFi in the wash area it would be awesome to see a battery-powered version you take with you. But in general this is a great hardware blueprint as many device have status LEDs that can be monitored in a similar way. If you want to keep the server in-house (literally in this case) check out the Minimal MQTT series [Elliot Williams] recently finished up. It uses a Raspberry Pi as the center server and an ESP8266 is one of the limitless examples of hardware that plays nicely with the protocol.

We love seeing hacks like this because not only does it conserve water and energy by reducing instances of rewashing, but it’s also a clever way to extend the life of an appliance and potentially save hundreds of dollars in replacing it. Add this to the bevvy of hacks that add convenience to one’s home — some of which produce delicious results.

Hackaday Prize Entry: A Raspberry Pi Project

June 23, 2016 by Brian Benchoff 40 Comments

There’s no piece of technology that has been more useful, more influential on the next generation of sysadmins and engineers, and more polarizing than the Raspberry Pi. For $35 (or just $5), you get a complete single board computer, capable of running Linux, and powerful enough to do useful work. For the 2016 Hackaday Prize, [Arsenijs] has created the perfect Raspberry Pi project. It’s everything you expect a Pi-powered project to be, and more.

While the Raspberry Pi, and the community surrounding the Raspberry Pi, get a lot of flak for the relatively simple approach to most projects which are effectively just casemods, critics of these projects forget the historical context of tiny personal computers. Back in the early ‘aughts, when Mini ITX motherboards were just being released, websites popped up that would feature Mini ITX casemods and nothing else. While computers stuffed into an NES, an old radio, or the AMD logo are rather banal projects today, I assure you they were just as pedestrian 15 years ago as well. Still, the creators of these Mini ITX case mods became the hardware hackers of today. It all started with simple builds, a Dremel, and some Bondo.

[Arsenijs] takes his Raspberry Pi project a bit further than a simple casemod, drawing influence from a Raspberry Pi smartphone, a Raspberry Pi security system, a Portable Raspberry Pi, and a Raspberry Pi wrist computer. These are all excellent projects in their own right, but [Arsenijs] is putting his own special twist on the project: he’s using a Raspberry Pi, and a few Raspberry Pi accessories.

While this project is first and foremost a Raspberry Pi project, [Arsenijs] isn’t limiting himself to the platform with the Broadcom chip. The team behind this Raspberry Pi project was busy porting the project to Odroid when the Banana Pi came out. This changed everything, a refactor was required, and then the Orange Pi was announced. Keeping up with technology is hard, and is a big factor in why this Raspberry Pi project hasn’t delivered yet. You can say a lot of things about the Raspberry Pi foundation, but at least their boards make a good attempt at forward compatibility.

Already [Arsenijs]’ Raspberry Pi project is one of the more popular projects on Hackaday.io, and is in the running for being one of the most popular projects in this year’s Hackaday Prize. Whether that popularity will translate into a minor win for this year’s Hackaday Prize remains to be seen, but it seems for [Arsenijs] that doesn’t matter; he’s already on the bleeding edge of Raspberry Pi projects.

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Machine Tool Build Is Anything But Boring

June 23, 2016 by Dan Maloney 19 Comments

“So just like every other great story in history, ours is going to start at the lathe.” Truer words were never spoken, and thus begins the saga of turning a bar of chrome-moly steel into a shop-built boring head.

You may have a few questions regarding [ThisOldTony]’s effort. First, unless you’re familiar with machine tooling, you may wonder what exactly a boring head is. The video below makes it plain, but the short answer is that it’s a tool to make holes. A boring head spins a boring bar with a cutting tool, and the head can be offset to spin the bar through an adjustable diameter. They’re great for making large holes of precise diameters – skip to around 25:30 to see it in action.

The other question might be: why does he spend so much time and effort building something he can just buy off the shelf? If you have to ask that question, we think you may be missing the point. [Tony] seems mainly interested in building tools; using them to make non-tool things is merely a happy accident. We totally respect that, and besides, just look at the quality of the tool he makes. We find his videos very entertaining, too – he’s got a great sense of humor and the video production quality is top-notch. Just watch out for banana peels and space-time continuum issues.

We love tools, and we really love tools that are custom made with this level of craftsmanship. For more quality toolmaking, check out this guitar-fretting jig or this belt grinder.

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A CNC You Could Pop-Rivet Together

June 23, 2016 by Gerrit Coetzee 22 Comments

You have to be careful with CNC; it’s a slippery slope. You start off one day just trying out a 3D printer, and it’s not six months before you’re elbow deep in a discarded Xerox looking for stepper motors and precision rods. This is evident from [Dan] and his brother’s angle aluminum CNC build.

Five or six years ago they teamed up to build one of those MDF CNC routers. It was okay, but really only cut foam. So they moved on to a Rostock 3D printer. This worked much better, and for a few years it sated them. However, recently, they just weren’t getting what they needed from it. The 3D printer had taught them a lot of new things, 3D modeling, the ins of running a CNC, and a whole slew of making skills. They decided to tackle the CNC again.

The new design is simple and cheap. The frame is angle aluminum held together with screws. The motion components are all 3D printed. The spindle is just an import rotary tool. It’s a simple design, and it should serve them well for light, low precision cuts. We suspect that it’s not the last machine the pair will build. You can see it in action in the video after the break.

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Custom Engine Parts From A Backyard Foundry

June 23, 2016 by Dan Maloney 40 Comments

Building a car engine can be a labor of love. Making everything perfect in terms of both performance and appearance is part engineering and part artistry. Setting your creation apart from the crowd is important, and what better way to make it your own than by casting your own parts from old beer cans?

[kingkongslie] has been collecting parts for a dune buggy build, apparently using the classic VW Beetle platform as a starting point. The air-cooled engine of a Bug likes to breathe, so [kingkongslie] decided to sand-cast a custom crankcase breather from aluminum.

Casting solid parts is a neat trick but hardly new; we’ve covered the techniques for casting plastic, pewter, and even soap. The complexity of this project comes from the fact that the part needs to be hollow. [kingkongslie] managed this with a core made of play sand and sodium silicate from radiator stop-leak solution hardened with a shot of carbon dioxide. Sure, it looks like a Rice Krispie treat, but a core like that will stand up to the molten aluminum while becoming weak enough to easily remove later. The whole complex mold was assembled, beer cans melted in an impromptu charcoal and hair-dryer foundry, and after one false start, a shiny new custom part emerged from the sand.

We’ve got to hand it to [kingkongslie] – this was a nice piece of work that resulted in a great looking part. But what we love about this is not only all the cool casting techniques that were demonstrated but also the minimalist approach to everything. We can all do stuff like this, and we probably should.

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