Superbly Synchronized Servos Swaying Softly

LEDs and blinky projects are great, and will likely never fade from our favor. But would you look at this sweeping beauty? This mesmerizing display is made from 36 micro servos with partial Popsicle sticks pasted on the arms. After seeing a huge display with 450 servos at an art museum, [Doug Domke] was inspired to make a scaled-down version.

What [Doug] didn’t scale down is the delightful visuals that simple servo motion can produce. The code produces a three-minute looping show that gets progressively more awesome, and you can stare at that after the break. Behind the pegboard, a single, hardworking Arduino Uno controls three 16-channel PWM controllers that sweep the servos. We like to imagine things other than Popsicle sticks swirling around, like little paper pinwheels, or maybe optical illusion wheels for people with strong stomachs.

You won’t see these in the video, but there are five ultrasonic sensors mounted face-up on the back of the pegboard. [Doug] has optional code built in to allow the servo sticks to follow hand movement. We hope he’ll upload a demo of that feature soon.

Servos can be hypnotic as well as helpful, as we saw in this 114-servo word clock.

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3D Printed Pen Plotter Is As Big As You Need It To Be

There’s nothing quite like building something to your own personal specifications. It’s why desktop 3D printers are such a powerful tool, and why this scalable plotter from the [Lost Projects Office] is so appealing. You just print out the end pieces and then pair it with rods of your desired length. If you’ve got some unusually large computer-controlled scribbling in mind, this is the project for you.

The design, which the team calls the Deep Ink Diver (d.i.d) is inspired by another plotter that [JuanGg] created. While the fundamentals are the same, d.i.d admittedly looks quite a bit more polished. In fact, if your 3D printed parts look good enough, this could probably pass for a commercial product.

For the electronics, the plotter uses an Arduino Uno and a matching CNC Shield. Two NEMA 17 stepper motors are used for motion: one to spin the rod that advances the paper, and the other connected to a standard GT2 belt and pulley to move the pen back and forth.

We particularly like the way [Lost Projects Office] handled lifting the pen off the paper. In the original design a solenoid was used, which took a bit of extra circuitry to drive from the CNC Shield. But for the d.i.d, a standard SG90 servo is used to lift up the arm that the pen is attached to. A small piece of elastic puts tension on the assembly so it will drop back down when the servo releases.

If this plotter isn’t quite what you’re after, don’t worry. There’s more where that came from. We’ve seen a number of very interesting 3D printed plotters┬áthat are just begging for a spot in your OctoPrint queue.


Taking a selfie before the modern smartphone era was a true endeavor. Flip phones didn’t have forward-facing cameras, and if you want to go really far back to the days of film cameras, you needed to set a timer on your camera and hope, or get a physical remote shutter. You could also try and create a self portrait on an Etch a Sketch, too, but this would take a lot of time and artistic skill. Luckily in the modern world, we can bring some of this old technology into the future and add a robot to create interesting retro selfies – without needing to be an artist.

The device from [im-pro] attaches two servos to the Etch a Sketch knobs. This isn’t really a new idea in itself, but the device also includes a front-facing camera, taking advantage of particularly inexpensive ESP32 Camera modules. Combining the camera features with [Bart Dring]’s ESP32 Grbl port is a winner. Check the code in [im-pro]’s GitHub.

Once the picture is taken, the ESP32 at the heart of the build handles the image processing and then drawing the image on the Etch a Sketch. The robot needs a black and white image to draw, and an algorithm for doing it without “lifting” the drawing tool, and these tasks stretch the capabilities of such a small processor. It takes some time to work, but in the end the results speak for themselves.

The final project is definitely worth looking for, if not for the interesting ESP32-controlled robot than for the image processing algorithim implementation. The ESP32 is a truly versatile platform, though, and is useful for building almost anything.

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Tea Bot Solves Another First World Problem

In the movie Wall-E, future humans live in floating chairs and have everything done for them. Today, we grumble if we have to go to physically find a light switch or a remote control. How far away can floating chairs with screens be? T2, the Tea Bot, gets us one step closer to that. Using a laser-cut frame, an ESP8266, and a servo motor, the T2 brews your tea for exactly the right amount of time.

We were kind of hoping the robot would at least dunk the tea bag in and out, but it does provide a web interface that lets you select the brew. Of course, the code is available, so you could make modifications — maybe turn on a hotplate underneath the cup.

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Let A Spooky Owl Tell You The Weather

There can be few readers who were young in the 1970s who did not want to share in the adventures of the fearless animated ghost-hunting young crime-fighters of Scooby-Doo. What do you remember from the series though? The Mystery Machine van? Scooby snacks? Or perhaps the improbably haunted theme parks whose owners would have got away with it if it hadn’t been for those pesky kids? For [Alex Shakespeare] it seems to have been the trope of haunted pictures whose subject’s eyes would follow the protagonists around the room, because when he made a wall-mounted weather indicator he gave it an owl with eyes doing just that.

The weather part of the device is straightforward enough, an ESP8266 board drives a set of servos that move dial indicators according to data from the Dark Sky API. The owl’s moving googly eyes are the party piece though, for them the ESP takes input from an Adafruit AMG8833 thermal sensor array and drives a servo and lever arrangement to do the moving. Finally, the thermal camera’s output is available to see on the ESP’s web server. All the details of the project can be found via a GitHub repository.

The result is shown in the video below the break, and as you might expect in the spirit of its inspiration it’s more comedic than haunting. But maybe there’s the root of the popularity of artworks that follow the viewer, of which this is merely the latest in a long line.

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Robot Arms Nudge The Hands Of Time In The Strangest Clock

We see a lot of clocks here at Hackaday. Digital clocks, retro clocks, lots of Nixie clocks, binary clocks, and clocks that appear to be designed specifically to be unreadable. But this dual-servo kinematic clock is something we haven’t seen yet, and it’s certainly worth a mention.

[mircemk]’s idea is simple and hearkens back to grammar school days when [Teacher] put a large cardboard clock dial on the blackboard and went through the “big hand, little hand” drill. In this case, the static cardboard clock has been replaced by a 3D-printed dial and hands, while a pair of servos linked together by two arms takes the place of the teacher. The video below shows it in action; the joint in the linkage between the two servos has a screw sticking out that can be maneuvered across the clock face to reposition the hands. It’s a little jittery, though; [mircemk] might want to tune the servo loops up a bit or tighten the linkage joints to make things a little smoother.

Even with the shakes, we find it wonderfully weird and hard to stop watching. It reminds us a bit of this luminous plotting clock from a while back – same linkage, different display.

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New Part Day: Lynxmotion Smart Servos

Anyone who shops for robotics kits would have come across a few designed by Lynxmotion. They’ve been helping people build robots since 1995, from robot arm kits to hexapod chassis and everything in between. We would expect these people know their motors, so when they launched their own line of servo motors called Lynxmotion Smart Servos (LSS), it is worth spending a bit of time to look over what they offer.

While these new devices have a PWM mode compatible with classic remote control servos, unleashing their full power requires bidirectional communication over a serial bus. We’ve previously given an overview of three serial bus servos already on the market for comparison. A quick look at the $68-$100 price tags listed on Lynxmotion’s parent company RobotShop made it clear they do not intend to compete on price, so what interesting features do these new kids on the block have?

Digging into product documentation found some great details. Acceleration and deceleration rates are adjustable, which can help with smoother robot movement. There’s also an adjustable level of “stiffness” that adds some “give” (compliance) so a robot won’t have to be as stiff as… well, a robot!

Mechanically, the most interesting internal component is the magnetic position sensor. They are far more precise than potentiometers, but more importantly, they allow positioning anywhere within full 360 degrees. Many other serial bus servos are constrained to positions within an arc less than 360 degrees leaving a blind spot.

An interesting quirk of the LSS offerings is that the serial communication protocol uses human-readable text characters, so sending a number 255 means transmitting a three byte string ‘2’, ‘5’, and ‘5’ instead of single byte 0xFF. This would make debugging our custom robot code far easier, at the cost of reduced bandwidth efficiency and loss of checksum for detecting communication errors. It’s a trade-off that some robot builders would be happy to make, but others might not.

Externally, these servos have bountiful mounting options including some we didn’t know to ask for. Historically Lynxmotion kits have used a wide variety of servo mounting brackets, so they are motivated to make mechanical integration easy. The most novel offering is the ability to bolt external gears to the servo body. A set of 1:3 gears allow for gearing the servo up or down, or you can use a set of 1:1 gears for a compact gripper.

As you’d expect of servos in this price range, they all have metal gears, but they also have the ability to power the motor directly from a battery pack (a 3 cell lithium polymer is recommended). There are additional features, like an RGB LED for visual feedback, which we didn’t cover here so dig into the documentation for more. We look forward to seeing how these interesting little actuators perform in future robotics projects.