3D Printed Wheels Passively Transform To Climb Obstacles

Wheels do a great job at rolling over all kinds of terrain, particularly if you pair them with compliant tires. However, they’re not perfect, and can get stumbled by things like large vertical steps. Enter the PaTS-Wheel — a compliant mechanism that can tackle such obstacles with ease.

The PaTS-Wheel takes advantage of printable flexural hinges. Under regular conditions, it exists as a simple round wheel. However, when presented with a step obstacle, its individual segments can bend and flex to grab on to the step and hoist the vehicle up. It all happens passively as a result of the wheel’s structure, no actuators or control system are needed to achieve this action.

The video below does a great job of explaining the concept in raw engineering terms, as well as showing it in action. If you really want to drill down though, dive into the research paper. The design outperformed smooth wheels and whegs in climbing ability, and was able to match smooth wheels in simple tests of flat ground power consumption. The results are very impressive.

We’ve seen other transforming wheels before, like these wheg-like constructions, but nothing so passive and elegant as these. Video after the break.

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An Elbow Joint That Can

We’re not certain whether [Paul Gould]’s kid’s prosthetic elbow joint is intended for use by a real kid or is part of a robotics project — but it caught our eye for the way it packs the guts of a beefy-looking motorized joint into such a small space.

At its heart is a cycloidal gearbox, in which the three small shafts which drive the center gear are driven by a toothed belt. The motive power comes from a brushless motor, which is what gives the build that impressive small size. He’s posted a YouTube short showing its internals and it doing a small amount of weight lifting, so it evidently has some pulling power.

If you’re interested in working with this design, it can be downloaded for 3D printing from Thingiverse. We think it could find an application in plenty of other projects, and we’d be interested to see what people do with it. There’s certainly a comparison to be maid over robotic joints which use wires for actuation.

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Roboticizing An Etch-a-Sketch

The Etch-a-Sketch was a popular toy, but a polarizing one. You were either one of those kids that had the knack, or one of the kids that didn’t. [Micah] was pretty firmly in the latter group, so decided to roboticize the Etch-a-Sketch so a computer could draw for him instead.

The build uses a pair of stepper motors attached to the Etch-a-Sketch’s knobs via 3D-printed adapters. It took [Micah] a few revisions to get the right design and the right motors for the job, but it all came together. A Raspberry Pi is charged with driving the motors to draw the desired picture.

Beyond the mechanics, [Micah] also does a great job of explaining the challenges around drawing and the drive software. Namely, the Etch-a-Sketch has a major limitation in that there’s no way to move the stylus without drawing a line. He accounts for this in his code for converting and drawing images.

The robot draws slowly but surely. The final result is incredibly impressive, and far exceeds what most of us could achieve on by hand. We’ve seen some similar builds in the past, too. Video after the break.

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Laser cut bug body with pincers and electronics to control the pincers

A Buggy Entry In The Useless Robot Category

No one loves a useless robot more than we do here at Hackaday. But if anyone does it might be [ARC385] with her Bug Bite Bot.

A true engineering marvel, [ARC385]’s bug bot extinguishes the candle on its own little birthday cupcake. Yup. That’s it! Even more peculiar, (and to be fair, somewhat fittingly) before her bug releases its less-than-crushing bite, it plays itself a little Happy Birthday jingle. Seems legit.

If you choose to build this little bug yourself, you’ll be happy to know that the electronics on this build are pretty straightforward. Servo motors control the pincers and a photoresistor detects the flame. [ARC385] tried using a flame sensor instead of the photoresistor, but mentioned she couldn’t get consistent performance at her required sensing distance. She also mentions that you’ll probably need to calibrate the photoresistor to ambient light if for whatever reason you choose to embark on this build yourself.

[ARC385] did a pretty good job with the laser-cut plywood to construct the bug, but using plywood adds a few more question marks to this already puzzling build. She even mentioned having to modify the pincers so they wouldn’t catch fire trying to extinguish the candle.

Would be cool if the candle could rekindle itself, but we can’t possibly support making this hack even more of a fire hazard than it already is.

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Fire Up The 3D Printer And Build Yourself A Spiderbot

Robots are cool, so check out [Atlin Anderson]’s Spiderbot (video, embedded below) which can be made with 3D printed parts, hobby servos, and ESP32-CAM module for control and a first-person view. Looking for a new project? All of the design details are shared online if you’d like to make a hexapod of your own.

We like the effort [Atlin] put into minimizing hardware fasteners in the design of the 3D-printed parts, and aiming for a modular concept that leaves things open for expansion or modification. There’s plenty of room in the chassis for more hardware, with a convenient peg system for snap-fitting assemblies.

Control is done wirelessly via a mobile phone with an app created using the MIT App Inventor, a fantastic tool that is still going strong as a capable and accessible way to make an Android app.

As for the ESP32-CAM module that drives it all, it is a great piece of hardware with capabilities that are leveraged very nicely here. We’ve seen other projects make good use of it as well, from this 1/64 scale micro RC car to an oddball tripod camera robot.

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Dodge, The Weird Tripod Robot

[hannu_hell] created Dodge as a “novel design of tripod.” It’s a small robotic device quite unlike anything else we’ve seen of late. It’s intended to be a self-mobile camera platform that can move itself around to capture footage as needed.

Dodge is essentially a two-legged robot with a large flat “foot” in the center. When stationary, it rests on this flat foot. When it needs to move, it can raise this center foot and rest on its two outside legs. If Dodge needs to move, it can crab back and forth in a line with these two legs. If it wants to turn, it can return to resting on its center foot, and pivot about its central axis. It can thus rotate itself and use its two outer legs to move further as needed.

Dodge does all this while carrying an ESP32 Cam module. The idea is that it’s a small mobile tripod platform with a live camera feed. It reminds us of various small monitoring robots from cartoons and anime.

Ultimately, it’s an interesting take on robot locomotion. Rather than walking with two legs or four legs and dynamic stability, it takes full advantage of static stability instead.

We’ve seen some wild roboticized camera rigs over the years. Video after the break.

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Vastly Improved Servo Control, Now Without Motor Surgery

Hobby servos are great, but they’re in many ways not ideal for robotic applications. The good news is that [Adam] brings the latest version of his ServoProject, providing off-the-shelf servos with industrial-type motion control to allow for much, much tighter motion tracking than one would otherwise be limited to.

Modifying a servo no longer requires opening the DC motor within.

The PID control system in a typical hobby servo is very good at two things: moving to a new position quickly, and holding that position. This system is not very good at smooth motion, which is desirable in robotics along with more precise motion tracking.

[Adam] has been working on replacing the PID control with a more capable cascade-based control scheme, which can even compensate for gearbox backlash by virtue of monitoring the output shaft and motor position separately. What’s really new in this latest version is that there is no longer any need to perform surgery on the DC motor when retrofitting a servo; the necessary sensing is now done externally. Check out the build instructions for details.

The video (embedded just below) briefly shows how a modified servo can perform compared to a stock one, and gives a good look at the modifications involved. There’s still careful assembly needed, but unlike the previous version there is no longer any need to actually open up and modify the DC motor, which is a great step forward.

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