Flexible Actuators Spring Into Action

November 1, 2020 by Roger Cheng 12 Comments

Most experiments in flexible robot actuators are based around pneumatics, but [Ayato Kanada] and [Tomoaki Mashimo] has been working on using a coiled spring as the moving component of a linear actuator. Named the flexible ultrasonic motor (FUSM), [Yunosuke Sato] built on top of their work and assembled a pair of FUSM into a closed-loop actuator with motion control in two dimensions.

A single FUSM is pretty interesting by itself, its coiled spring is the only mechanical moving part. An earlier paper published by [Kanada] and [Mashimo] laid out how to push the spring through a hole in a metal block acting as the stator of this motor. Piezoelectric devices attached to that block minutely distorts it in a controlled manner resulting in linear motion of the spring.

For closed-loop feedback, electrical resistance from the free end of the spring to the stator block can be measured and converted to linear distance to within a few millimeters. However, the acting end of the spring might be deformed via stretching or bending, which made calculating its actual position difficult. Accounting for such deformation is a future topic for this group of researchers.

This work was presented at IROS2020 which like many other conferences this year, moved online and became IROS On-Demand. After a no-cost online registration we can watch the 12-minute recorded presentation on this project or any other at the conference. The video includes gems such as an exaggerated animation of stator block deformation to illustrate how a FUSM works, and an example of the position calculation challenge where the intended circular motion actually resulted in an oval.

Speaking of conferences that have moved online, we have our own Hackaday Remoticon coming up soon!

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Destroy My Vegetable Garden? Oh Hail No!

January 20, 2020 by Kristina Panos 13 Comments

Building and maintaining a garden takes a lot of work. And unless you have a greenhouse, you’re forced to leave your hard work outside to fend for itself against the double-edged sword of the elements. Rain and sun are necessary, but hard, pelting hail is never welcome. Just ask [Nick Rogness]. He didn’t go through all the trouble of building a 12’x12′ garden and planting tasty vegetables just to have Mother Nature spew her impurity-filled ice balls on it every other night during the summertime.

[Nick] did what any of us would do: fight back with technology. His solution was to build a retractable roof that covers the garden with a heavy duty tarp. A Raspberry Pi Zero W controls pair of linear actuators via motor controllers, and [Nick] put a limit switch in each of the four corners to report on the roof status. He can run the roof manually, or control it with his phone using MQTT. The whole thing runs on a 12V marine battery that gets charged up by a solar panel, so part of the interface is dedicated to reporting the battery stats.

[Nick] ran out of time to implement all the features he wanted before the season started, but there’s always next year. He has big plans that include soil moisture sensors, rain detection sensors, and an automatic watering system that collects and uses rain water. We planted the bite-size demo video for you after the break — just wash the dirt off and you’re good to go.

Maybe someday [Nick] will create a system that can automate the entire garden, like the FarmBot. Hey, we’re just trying to plant seeds of ideas.

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DIY Music Controllers For Raging With Machines

December 9, 2019 by Kristina Panos 13 Comments

[Tristan Shone], aka Author & Punisher, found a way to make industrial music even heavier. This former mechanical engineer from Boston crafted his one-man band in the university fab labs of Southern California while pursing an art degree. He started machining robust custom MIDI controllers that allow him to get physical while performing, instead of hunching over tiny buttons and trying to finesse microscopic touch pad-style pitch sliders.

Starting about ninety seconds into the video after the break, [Tristan] explains his set up and walks through each of his handmade controllers, all of which are built on Arduinos and Raspberry Pis.

Our favorite is probably Grid Iron, because it looks like the most fun. Grid Iron is a rhythm controller that works by running back and forth and side-to-side over a grid of machined textures that act like speed bumps. A spring-loaded stylus picks up the textures, and an encoder translates them to sound. Eight buttons along the 3D-printed pistol grip let [Tristan] make changes on the fly.

Tired of twiddling tiny knobs, [Tristan] made Big Knobs, a set of three solid aluminum knobs that look to be 3-4″ in diameter. These are assigned jobs like delay and filter, and their weight combined with ball bearings allows them to spin almost indefinitely while [Tristan] injects other sounds into the mix.

[Tristan] has made a few custom microphones to make the most of his voice. One is a trachea mic made from four piezos strapped to his throat that picks up every possible vocal utterance and other guttural sounds quite nicely. The other is an 8-pack of mics built into a curved metal box. He can assign a different effect to each one and do things like turn a breathy scream into the sounds of swelling cymbals.

There are more machines not covered in the video, and you can read about those on [Tristan]’s site. In a bonus video after the break, [Tristan] discusses a trio of pneumatically-driven mask controllers he made.

Don’t have a machine shop at your disposal? Dig out that fidget spinner and get moving on your own MIDI controller.

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Tiny Robots That Grow Taller (And Wider)

October 4, 2019 by Danie Conradie 9 Comments

Sometimes one just needs an extra hand or six around the workbench. Since you’re a hacker that should take the form of a tiny robot swarm that can physically display your sensor data, protect you against a dangerously hot caffeine fix and clean up once you’re done. [Ryo Suzuki] and [Clement Zheng] from the University of Colorado Boulder’s ATLAS Institute developed ShapeBots, small shape-shifting swarm robots that aim to do exactly that and more.

The robots each consist of a cube shaped body with 2 small drive wheels, onto which 1-4 linear actuator modules can attach in various positions. For control the robots’ relative positions are tracked using an overhead camera and is shown performing the tasks mentioned above and more.

To us the actuators are the interesting part, consisting of two spools of tape that can extend and retract like a tape measure. This does does lead us to wonder: why we haven’t seen any hacks using an old tape measure as a linear actuator? While you likely won’t be using it for high force applications, it’s possible to get some impressive long reach from a small from factor. This is exactly what the engineers behind the Lightsail 2 satellite used to deploy it’s massive space sail. Space the two coils some distance apart and you can even achieve full 2-axis motion.

You can also control your swarm using your favourite wifi chip or have them skitter around using vibration or 3D print some linear actuators.

Thanks for the tip [Qes]!

Plasma Globe Reveals Your Next Clue

June 24, 2019 by Sven Gregori 7 Comments

If you like solving puzzles out in the real world, you’ve probably been to an escape room before, or are at least familiar with its concept of getting (voluntarily) locked inside a place and searching for clues that will eventually lead to a key or door lock combination that gets you out again. And while there are plenty of analog options available to implement this, the chances are you will come across more and more electronics-infused puzzles nowadays, especially if it fits the escape room’s theme itself. [Alastair Aitchison] likes to create such puzzles and recently discovered how he can utilize a USB powered plasma globe as a momentary switch in one of his installations.

The concept is pretty straightforward, [Alastair] noticed the plasma globe will draw significantly more current when it’s being touched compared to its idle state, which he measures using an INA219 current shunt connected to an Arduino. As a demo setup in his video, he uses two globes that will trigger a linear actuator when touched at the same time, making it an ideal multiplayer installation. Whether the amount of fingers, their position on the globe, or movement make enough of a reliable difference in the current consumption to implement a more-dimensional switch is unfortunately not clear, but definitely something worth experimenting with.

In case you’re planning to build your own escape room and are going for the Mad Scientist Laboratory theme, you’ll obviously need at least one of those plasma globes sparking in a corner anyway, so this will definitely come in handy — maybe even accompanied by something slightly larger? And for all other themes, you can always resort to an RFID-based solution instead.

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Amplifier Controlled Motorized Display

October 6, 2018 by Tom Nardi 4 Comments

It’s easy to get jaded by gadgets like the Chromecast or Sonos, which let the user control AV equipment remotely from a mobile device or computer. You can pick something to play from your phone and send it off to your speakers via the magic of Wi-Fi. But it’s still nice to have a display to look at for music visualizations and that sort of thing, at least occasionally.

To address this only occasional desire to have a display on your media setup, you could follow in the footsteps of [Steven Elliott] and create a DIY motorized display which only pops up when needed. Inspired by seeing videos of TVs rising out of cabinets and other such trickery, he decided to create his own version using an old computer monitor he had lying around.

The monitor is lifted with a beefy linear actuator, which has been placed inside of a square metal fence post to keep from rotating. It already had a power supply and control board with relays for extending and retracting, so [Steven] just needed to find a convenient way of firing them off.

The answer came from a somewhat unconventional source: his amplifier. [Steven] explains that many amplifiers feature a “Trigger Output”, which uses a standard stereo 3.5mm connector and sends a 12V pulse to connected device. This is generally used to turn on downstream devices when the amplifier switches to the respective input. It’s too short and not nearly powerful enough to close the actuators relays, but it’s easy enough to detect.

[Steven] uses a LeoStick microcontroller to wait for the pulse from the amplifier, and then use that to raise or lower the display depending on the selected input. There’s also a SPST momentary switch which can be used to trigger the actuator manually. Beyond the fact the linear actuator is a bit loud, he says the setup works very well and prevents him from having to start up his projector if he just wants to take a quick glance at what’s playing or program his DVR.

We don’t see many motorized display lifts like this anymore, not since wall mounted LCDs became popular anyway. But it’s still a cool effect, and today made quite a bit easier thanks to the fact that TVs and monitors no longer weigh as much as a small car.

[Thanks to Baldpower for the tip.]

Build Your Next Dancing Robot From Empty Soda Bottles

October 5, 2018 by Richard Baguley 2 Comments

When you think about the materials for your next large dancing robot build, soda bottles might not be the first thing that springs to mind. But they could work, according to TrussFab, a project from a group of students at the Hasso Plattner Instituit. Their system uses empty coke bottles and 3D printed connectors to build large structures, modeled in software that checks their load balance and safety. The team has modeled and built designs up to 5 meters high. Now, the project has taken a step further by adding linear actuators and hinges to the mix so you can create things that move, including a 4-meter high animatronic robot.

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