Unique Strandbeest Stands Tall With Line Of Legs

June 8, 2020 by Tom Nardi 1 Comment

Multiple rows of intricately articulated legs are the defining characteristic of the Strandbeest, but [James Bruton] wondered if he could reduce that down to a single row using the same principles at work in a self-balancing two wheeled robot. While it’s perhaps a bit early to call his experiments a complete success, the first tentative steps taken by his (relatively) svelte Strandbeest certainly look promising.

Initially the robot only had two pairs of legs, but in testing [James] found this arrangement to be a bit unstable. By bringing the total count to four legs per side and improving the counterweight arrangement, the bot has been able to walk the length of the workshop. Unfortunately, an issue with the leg design seems to be preventing the Strandbeest from taking any backward steps.

Normally this wouldn’t be that big of a problem, but in this case it’s keeping the Strandbeest from being able to self-balance while standing still. In other words, the robot needs to keep moving forward or it will fall over. Still, [James] thinks the idea has promise and wants to continue experimenting with the bot in a larger area.

Specifically, he wants to see if the dual-motor robot can turn by varying the speed the two sets of legs are running at. If it can walk in a tight enough circle, it could keep right on marching until the power runs down. Sounds more than a little nightmarish to us, but we’d still like to see it.

Reader’s may recall [James] from this other another robotic projects, such as the phenomenal OpenDog. We don’t know where his obsession of legged robots comes from, but we certainly aren’t complaining.

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Dual-Wielding Robot Carves 3D Shapes From Foam With Warped Wire

June 3, 2020 by Dan Maloney 28 Comments

“Every block of expanded polystyrene foam has a statue inside it and it is the task of the dual-arm hot wire-wielding robot to discover it.” — [Michelangelo], probably.

Be prepared to have your mind blown by this dual-wielding hot-wire 3D foam cutter (PDF). We’ve all seen simple hot-wire cutters before, whether they be manual-feed cutters or CNC-controlled like a 3D-printer. The idea is to pass current through a wire to heat it up just enough to melt a path as it’s guided through a block of polystyrene foam. Compared to cutting with a knife or a saw, hot-wire cuts are smooth as silk and produces mercifully little of that styrofoam detritus that gets all over your workspace.

But hot-wire cutters can’t do much other than to make straight cuts, since the wire must be kept taut. “RoboCut”, though, as [Simon Duenser] and his colleagues at ETH Zurich call their creation, suffers from no such limitations. Using an ABB YuMi, a dual-arm collaborative robot, they devised a method of making controlled curved cuts through foam by using a 1-mm thick deformable rod rather than a limp and floppy wire for the cutting tool. The robot has seven degrees of freedom on each arm, and there’s only so much the rod can deform before being permanently damaged, so the kinematics involved are far from trivial. Each pass through the foam is calculated to remove as much material as possible, and multiple passes are needed to creep up on the final design.

The video below shows the mesmerizing sweeps needed to release the Stanford bunny trapped within the foam, as well as other common 3D test models. We’re not sure it’s something easily recreated by the home-gamer, but it sure is fun to watch.

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Useless Machine For An Existential Quandary

May 27, 2020 by Bryan Cockfield 7 Comments

There’s no project that dives into existential quandaries more than a useless machine, as they can truly illustrate the futility of existence by turning themselves off once they have been powered on. Typically this is done with a simple switch, but for something that can truly put the lights out, and then re-illuminate them, [James]’s latest project is a useless machine that performs this exercise with a candle.

The project consists of two arms mounted on a set of gears. One arm has a lighter on it, and the other has a snuffer mounted to a servo motor. As the gears rotate, the lighter gets closer to the candle wick and lights it, then the entire assembly rotates back so the snuffer can extinguish the flame. Everything is built around an Arduino Nano, a motor driver powering a Pitman gear motor, and a set of Hall effect sensors which provide position data back to the microcontroller.

If you’re in the mood for a little existential angst in your own home, [James] has made the project files available on his GitHub page. We always appreciate a useless machine around here, especially a unique design like this one, and one which could easily make one recognize the futility of lighting a candle at all.

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Assemble Your (Virtual) Robotic Underground Exploration Team

May 26, 2020 by Roger Cheng 6 Comments

It’s amazing how many things have managed to move online in recent weeks, many with a beneficial side effect of eliminating travel making them more accessible to everyone around the world. Though some events had a virtual track before it was cool, among them the DARPA Subterranean Challenge (SubT) robotics competition. Recent additions to their “Hello World” tutorials (with promise of more to come) have continued to lower the barrier of entry for aspiring roboticists.

We all love watching physical robots explore the real world, which is why SubT’s “Systems Track” gets most of the attention. But such participation is necessarily restricted to people who have the resources to build and transport bulky hardware to the competition site, which is just a tiny subset of all the brilliant minds who can contribute. Hence the “Virtual Track” which is accessible to anyone with a computer that meets requirements. (64-bit Ubuntu 18 with NVIDIA GPU) The tutorials help get us up and running on SubT’s virtual testbed which continues to evolve. With every round, the organizers work to bring the virtual and physical worlds closer together. During the recent Urban Circuit, they made high resolution scans of both the competition course as well as participating robots.

There’s a lot of other traffic on various SubT code repositories. Motivated by Bitbucket sunsetting their Mercurial support, SubT is moving from Bitbucket to GitHub and picking up some housecleaning along the way. Together with the newly added tutorials, this is a great time to dive in and see if you want to assemble a team (both of human collaborators and virtual robots) to join in the next round of virtual SubT. But if you prefer to stay an observer of the physical world, enjoy this writeup with many fun details on systems track robots.

Spherical Quadruped Arduino Robot

May 21, 2020 by Orlando Hoilett 9 Comments

[Greg06] started learning electronics the same way most of us did: buy a few kits, read a few tutorials, and try your hardest to put a few things together. Sound familiar? After a while, you noticed your skills started increasing, and your comfort level with different projects improved as well. Eventually, you try your hand at making your own custom projects and publishing your own tutorials.

Few are lucky to have a first-project as elaborate as [Greg06’s] quadruped robot. We don’t know about you, but for some of us, we were satisfied with blinking two LEDs instead of just one.

[Greg06’s] robot has a quadruped based, housed within a 3D printed spherical body. The legs are retractable and are actuated by tiny servo motors inside the body. [Greg06] even included an ultrasonic distance sensor for the obstacle avoidance mechanism. Honestly, if it weren’t for the ultrasonic distance sensor protruding from the spherical body, you might think that the entire robot was just a little Wiffle ball. This reminds us of another design we’ve seen before.

If that weren’t enough, the spherical head can rotate, widening the range of the ultrasonic distance sensor and obstacle avoidance mechanism. This is accomplished by attaching another servo motor to the head.

Pretty neat design if you ask us. Definitely one of the coolest quadrupeds we’ve seen.

Wall-Climbing Robot Grabs Prize

May 19, 2020 by Bryan Cockfield 24 Comments

Gravity is a nice thing to have most of the time, but sometimes it would be nice to be able to ignore it for certain applications. Rock climbing, for example, would be much easier, as would performing bridge inspections in the way that a group of mechanical engineering cadets (students) at The Citadel, a military college in South Carolina, were tasked with doing. Frustrated with the amount of traffic backups that normal bridge inspections caused, they invented a robot that defies gravity, and won a $10k prize for their efforts.

The result is essentially an RC car with a drone built in, or looking at it another way it’s a drone with wheels. The car is able to drive on vertical surfaces to inspect the bridges by using its propellers to force itself onto the surface. The lack of complicated moving parts or machinery, like a cable suspension system or other contraption, makes this device exceptionally versatile for the task at hand, reduces the amount of time needed for inspections, and can do them more safely and without closing lanes of traffic. The group hopes to build a second prototype soon and present it to the Department of Transportation for approval for more widespread use.

The need for tools like these is in high demand now as well, especially in the United States where crumbling infrastructure is often not thought about, taken seriously, or prioritized. Even for bridges that aren’t major pieces of infrastructure, tools like these will prove to be very useful.

Thanks to [Ben] for the tip!

Robotic Basketball Hoop V2

May 19, 2020 by Bryan Cockfield 12 Comments

A few weeks ago, [Shane Wighton] created a basketball backboard which made it impossible to miss a shot even remotely close to the hoop. As a passive device, though, the backboard had its limits. Shots with tremendous velocity wouldn’t go in, and (like most backboards) it was missing facial recognition software. So he got to work on a second version which solves those issues, and takes a more active role in the game.

This version is flat, and looks largely unassuming until a game begins. The flat backboard is mechanized and includes a camera, so incoming shots can be analyzed in real-time while the backboard is moved into a position to direct the ball into the net. Or, since it does include facial recognition, the backboard can always send the ball away from the hoop, ensuring that [Shane] always wins basketball games no matter how many shots his opponent takes.

If you didn’t get a chance to see the original, we featured that a while back, and it’s truly a wonder when you learn about how much analysis went into creating the shape. The new version is even more impressive, doing all of that math in real time, and we can’t wait to see what [Shane] comes up with next.

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