Ourobot: What Happens When A Snake Bot Swallows Its Own Tail

July 20, 2016 by Elliot Williams 21 Comments

For all their joking about “reinventing the wheel”, the team behind Ourobot made a very cool robot (German, automatic translation here). The team, at the University of Applied Sciences in “Bielefeld, Germany“, built their wheel out of twelve segments, each with its own servo motor, a 3D-printed case, and a pressure sensor mounted on the outside of the wheel. The latter, plus some clever programming, allows the robot wheel to vary its circular gate and climb up over obstacles automatically.

There are a bunch of interesting constraints in designing the control for this bot. The tracks on the ground, naturally, have to adjust their relative angles so that they lie each flat on the surface, even if that surface isn’t itself flat or level. The segments in the air are unconstrained, but the sum of all the servos’ interior angles has to add up to 1800 degrees, and these angles control where its center of gravity is.

Our head is spinning. The paper, “OUROBOT – A Self-Propelled Continuous-Track-Robot for Rugged Terrain” is unfortunately behind the IEEE paywall, but goes into detail if you can find it. Continue reading “Ourobot: What Happens When A Snake Bot Swallows Its Own Tail” →

Simple Beetle Robot Uses Smoking Soldering Iron

July 20, 2016 by Al Williams 34 Comments

As robot projects go, [creative ideas km]’s isn’t going to impress many Hackaday readers. Still, as an art project or something to do with the kids, it might be fun. But the reason it caught our interest wasn’t the actual robot, but the improvised soldering iron used in its construction.

The robot itself isn’t really autonomous. It is just a battery, a motor, and a switch. The motor vibrations make the robot scoot around on its bent copper wire legs. Some hot glue holds it all together, but the electrical wiring is soldered.

If you look at the video below, you’ll see the soldering is done with an unusual method. A disposable lighter generates a flame that hits an attached copper wire with a coil wound in it. The coil acts as a heat exchanger, and the wire becomes a soldering iron tip.

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Giant Spider Roams The Streets

July 16, 2016 by Jenny List 30 Comments

There is a giant spider the size of a house stretching its massive, delicate legs as it parades through the French city of Nantes. Is the Arthropod Apocalypse upon us? Fortunately not, for this arachnid is the latest in a series of performance pieces by a French theatre company, La Machine.

Like the rest of La Machine’s productions, this spider is a large hydraulically controlled model driven not by a computer with a single operator but by a team of operators perched inside and underneath the mechanism who turn the operation of the spider’s legs into a piece of complex choreography. They in turn are aided by a team on the street who ensure that any manoeuvres are executed safely. The spider only gives the appearance of walking as it is supported on a hydraulic arm from a wheeled vehicle that carries its power plant, so freed of the requirement for support from its legs it can move with extreme grace.

The video below shows the spider inching its way underneath a set of tram cables. There is more video on the page linked above.

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Code Craft – Embedding C++: Multitasking

July 15, 2016 by Rud Merriam 24 Comments

We’re quite used to multitasking computer systems today. Our desktops run email, a couple of browsers in different workspaces, a word processor, and a few other applications, apparently all at once. Looking behind the scenes using a system monitor or task manager program reveals a multitude of other programs running in support of our activities. Of course, any given CPU is running a maximum of one program at a time. Multitasking is simply the practice of switching between active processes fast enough to give the illusion of simultaneity.

The roots of multiasking go way back. In the early days, when computers cost tons of money, the thought of an idle system was anathema. Teletype IO was slow compared to the processor, and leaving the processor waiting idle for a card reader to slurp in the next card was outrageous. The gurus of the time worked to fill that idle time with productive work. That eventually led to systems that would run multiple programs at one time, and eventually to more finely grained multitasking within a program.

Modern multitasking depends on support from the underlying API of an operating system. Each OS uses its own techniques, making it difficult to write portable code. The C++ 2011 standard increased the portability of the language by adding concurrency routines to the Standard Template Library (STL). These routines use the API of the OS. For instance, the Linux version uses the POSIX threading library, pthread. The result is a minimal, but useful, capability for building upon in later standards. The C++ 2017 standard development activities include work on parallelism and concurrency.

In this article, I’ll work through some of the facilities for and pitfalls in writing threaded code in C++.

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LEGO Monowheel Corners Like It’s On Rails

July 14, 2016 by Steven Dufresne 6 Comments

[Jason]’s at it again. This time the LEGO maestro is working on a LEGO BB-8 droid. As a first step he’s made a motorized monowheel that not only races along hallways and through living rooms at the peril of any passing people, but turns as well.

To drive it forward there’s an axle that runs across the center of the wheel and a motor that rotates that axle. He’s also included some weight bricks. Without the mass of those bricks for the rotation to work against, the motor and axle would just spin in place while the friction of the floor keeps the wheel from rotating. If you’ve seen the DIYer’s guide to making BB-8 drive systems, you’ll know that this is classified as an axle drive system.

LEGO monowheel interior shown while leaning to turn

For steering the monowheel left or right he has another mass located just above the axle. Shifting the mass to the left causes the monowheel to lean and move in that direction. Shifting the mass to the right makes the wheel move to the right in the same fashion. Being ever efficient, [Jason] has the motor that shifts the mass doubling as the mass itself.

As with any proof-of-concept, there are still some issues to work out. When turning the wheel left or right it can tip onto its side. Ridges on both sides of the wheel’s circumference reduce the chances of that happening but don’t eliminate it altogether. Also, the steering mass/motor doesn’t yet have a self-centering mechanism; after a turn it’s up to the person holding the remote control to find center. If the mass isn’t correctly centered after a turn, there tends to be some wobble.

As always, we’re looking forward to seeing how [Jason] solves those issues but first he’ll have to put it back together since, as you can see from the video below, it didn’t quite pass the stair test.

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Highlights From Robotic Shipwreck Exploration

July 13, 2016 by Donald Papp 9 Comments

DIY Research Vessel in use, while ROV is busy below. [Source: NYT]

OpenROV shared the results of their June 2016 underwater expedition to locate and robotically explore the wreck of the S.S. Tahoe, currently sitting at a depth of 150m in Lake Tahoe. Back in 1940 the ship was intentionally scuttled in shallow water, but unexpectedly slid to a much deeper depth. OpenROV used a modified version of their new Trident design to dive all the way down to the wreck and take a good look at things, streaming it over the internet in the process.

We previously covered the DIY research vessel that was designed and created as a floating base station for the ROV while it located and explored the wreck, and now the results are in! The video highlights of the expedition are below, as is a video tour of the ROV used and the modifications required to enable it to operate at 150m.

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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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