R/C Bot Takes Your Strawberries Away

July 10, 2016 by Steven Dufresne 16 Comments

Don’t let the friendly smile on this RC cart fool you, it will take your strawberries away — though that’s kinda the point. It’s an RC car that [transistor-man] and a few friends modified for carrying freshly picked strawberries at strawberry fields so that you don’t have to.

RC strawberry carrying robot before putting on the cooler — RC strawberry carrying robot – WIP

They started with an older Traxxas Emaxx, a 4-wheel drive RC monster truck. The team also bought a suitable sized water cooler at a local hardware store. A quick load test showed that 5lbs collapsed the springs and shock absorbers, causing the chassis to sink close to the ground. The team had two options: switching to stronger springs or locking out the springs altogether. They decided to replace one set of shocks with metal plates effectively locking them. After that it was time for some CAD work, followed by the use of a water jet to cut some aluminum plate. They soon had a mounting plate for the water cooler to sit in. This mounting plate was attached to 4 posts which originally held the vehicle’s Lexan body. A bungee cord wrapped around the cooler and posts on the mounting plate holds the cooler in place.

Some initial testing showed that the vehicle moved too fast even in low gear and tended to tip over, as you can see in the first video below. Some practice helped but a 3:1 reduction planetary gearbox brought the vehicle down to walking speed, making a big difference. A trip was arranged to go to local strawberry picking field at Red Fire Farms, but not without some excitement first. At 1AM the UNIK 320A High Voltage Speed controller emitted some magic smoke. A quick check with a thermal-camera found the culprit, one of the MOSFETs had failed, and after swapping it with one that was close enough they were back in business.

As you can see in the second video below, testing in the strawberry field went very well, though it wasn’t without some tipping. Kids also found it a fun diversion from picking strawberries, alternating between mock fright and delight.

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Makerspace North, From Empty Warehouse To Maker Magnet

June 30, 2016 by Steven Dufresne 5 Comments

Makerspace North is unique out of the 5 makerspaces in the Ottawa, Canada area in that it started life as an empty 10,000 square foot warehouse with adjoining office spaces and large open rooms, and has let the community fill it, resulting in it having become a major hub for makers to mix in all sorts of ways, some unexpected.

Many makerspaces are run by an organization that provides tools that groups or individuals use, along with qualification courses for select tools. Makerspace North, on the other hand, provides the space and lets the community provide the maker component. The result is a variety of large scale events from indoor drone flying and various types of maker faire style days, to craft shows, garage sales, and even concerts. Smaller meet-ups, most often open to anyone, are held by such groups as the Ottawa Robotics Club and the Ottawa Electronics Club as well as some more general ones. Courses offered by the community are also as varied.

This also means that the owners of Makerspace North don’t provide tools for people to use, but instead provide dedicated rental space. That doesn’t mean there aren’t tools — it means that Makerspace North encompasses a microcosm of various renters who fill out the task of things like tool rental. This is just one example of how the community has embraced the unique approach. Let’s take a closer look at that and a few other novelties of this system.

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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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Real World Race Track Is Real Hack

June 22, 2016 by Steven Dufresne 16 Comments

[Rulof] never ceases to impress us with what he comes up with and how he hacks it together. Seriously, how did he even know that the obscure umbrella part he used in this project existed, let alone thought of it when the time came to make a magnet mount? His hack this time is a real world, tabletop race track made for his little brother, and by his account, his brother is going crazy for it.

His race track is on a rotating table and consists of the following collection of parts: a motor, bicycle wheel, casters from a travel bag, rubber bands (where did he get such large ones?), toy car and steering wheel from his brother, skateboard wheels, the aforementioned umbrella part and hard drive magnets. In the video below we like how he paints the track surface by holding his paint brush fixed in place and letting the track rotate under it.

From the video you can see the race track has got [Rulof] hooked. Hopefully he lets his brother have ample turns too, but we’re not too sure. Some additions we can imagine would be robotics for the obstacles, lighting, sounds and a few simulated explosion effects (puffs of flour?).

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Wrangling High Voltage

June 15, 2016 by Steven Dufresne 28 Comments

Working with high voltage is like working with high pressure plumbing. You can spring a leak in your plumbing, and of course you fix it. And now that you’ve fixed that leak, you’re able to increase the pressure still more, and sometimes another leak occurs. I’ve had these same experiences but with high voltage wiring. At a high enough voltage, around 30kV or higher, the leak manifests itself as a hissing sound and a corona that appears as a bluish glow of excited ions spraying from the leak. Try to dial up the voltage and the hiss turns into a shriek.

Why do leaks occur in high voltage? I’ve found that the best way to visualize the reason is by visualizing electric fields. Electric fields exist between positive and negative charges and can be pictured as electric field lines (illustrated below on the left.) The denser the electric field lines, the stronger the electric field.

Weak and strong electric fields

Ionization in electric fields

The stronger electric fields are where ionization of the air occurs. As illustrated in the “collision” example on the right above, ionization can happen by a negatively charged electron leaving the electrically conductive surface, which can be a wire or a part of the device, and colliding with a nearby neutral atom turning it into an ion. The collision can result in the electron attaching to the atom, turning the atom into a negatively charged ion, or the collision can knock another electron from the atom, turning the atom into a positively charged ion. In the “stripping off” example illustrated above, the strong electric field can affect things more directly by stripping an electron from the neutral atom, again turning it into a positive ion. And there are other effects as well such as electron avalanches and the photoelectric effect.

In either case, we wanted to keep those electrons in the electrically conductive wires or other surfaces and their loss constitutes a leak in a very real way.

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World's tiniest violin, using Project Soli and finger gestures

World’s Tiniest Violin Uses Radar And Machine Learning

June 15, 2016 by Steven Dufresne 19 Comments

The folks at [Design I/O] have come up with a way for you to play the world’s tiniest violin by rubbing your fingers together and actually have it play a violin sound. For those who don’t know, when you want to express mock sympathy for someone’s complaints you can rub your thumb and index finger together and say “You hear that? It’s the world’s smallest violin and it’s playing just for you”, except that now they can actually hear the violin, while your gestures control the volume and playback.

[Design I/O] combined a few technologies to accomplish this. The first is Google’s Project Soli, a tiny radar on a chip. Project Soli’s goal is to do away with physical controls by using a miniature radar for doing touchless gesture interactions. Sliding your thumb across the side of your outstretched index finger, for example, can be interpreted as moving a slider to change the numerical value of something, perhaps turning up the air conditioner in your car. Check out Google’s cool demo video of their radar and gestures below.

Project Soli’s radar is the input side for this other intriguing technology: the Wekinator, a free open source machine learning software intended for artists and musicians. The examples on their website paint an exciting picture. You give Wekinator inputs and outputs and then tell it to train its model.

The output side in this case is violin music. The input is whatever the radar detects. Wekinator does the heavy lifting for you, just give it input like radar monitored finger movements, and it’ll learn your chosen gestures and perform the appropriately trained output.

[Design I/O] is likely doing more than just using Wekinator’s front end as they’re also using openFrameworks, an open source C++ toolkit. Also interesting with Wekinator is their use of the Open Sound Control (OSC) protocol for communicating over the network to get its inputs and outputs. You can see [Design I/O]’s end result demonstrated in the video below.

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High Voltage Please, But Don’t Forget The Current

June 8, 2016 by Steven Dufresne 30 Comments

In high voltage applications involving tens of thousands of volts, too often people think about the high voltage needed but don’t consider the current. This is especially so when part of the circuit that the charge travels through is an air gap, and the charge is in the form of ions. That’s a far cry from electrons flowing in copper wire or moving through resistors.

Consider the lifter. The lifter is a fun, lightweight flying machine. It consists of a thin wire and an aluminum foil skirt separated by an air gap. Apply 25kV volts across that air gap and it lifts into the air.

Lifter flying with high voltage power supply

Lifter parts

So you’d think that the small handheld Van de Graaff generator pictured below, that’s capable of 80kV, could power the lifter. However, like many high voltage applications, the lifter works by ionizing air, in this case ionizing air surrounding the thin wire resulting in a bluish corona. That sets off a chain of events that produces a downward flowing jet of air, commonly called ion wind, lifting the lifter upward.

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