3D Printed Tank Takes On The Elements

May 16, 2021 by Lewin Day 4 Comments

Commercially available radio control tanks are fun and all, but sometimes you’ve just got to build your own. [Let’s Print] did just that, whipping up a tank on his 3D printer before taking it out in the snow.

The tank is a fairly straightforward build, relying on a pair of brushed motors for propulsion, controlled by twin speed controllers hooked up to standard radio control hardware. Everything else is bespoke, however, from the 3D printed gearboxes, to the chassis and the rather aggressive-looking tracks. The pointed teeth of the latter leave deep indentations when the tank cruises around on mud, though weren’t quite enough to stop the little tank from getting high-centered in deep snow.

The build isn’t for the impatient, however. [Let’s Print] notes that the tracks alone took over 80 hours to run off in PETG, let alone the rest of the frame and gearboxes. However, we’re sure it was a great learning experience, and great fun to drive outside. Now the next step is surely to go bigger. Video after the break.

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Robotic Bartender Built With Industrial-Grade Hardware

May 15, 2021 by Lewin Day 12 Comments

Robotic bartenders are a popular project around these parts. If there’s one thing hackers love, after all, it’s automating tasks – as much for the challenge as for the actual time saved. This build from a group of [Teknic Servo] engineers is an impressive example of what can be done with some industrial-grade hardware.

The bartender is built as a demo project for the ClearCore controller, [Teknic’s] industrial-grade device capable of interfacing with a whole bunch of servomotors and sensors to get the job done. The controller is hooked up to a bunch of ClearPath servomotors that handle spinning the bottle carousel, muddling or stirring the beverage, or transporting the drinking glass through the machine. There’s also several interlocks to avoid the patron coming into contact with the bartender’s moving parts while it’s working, and a standard bar-style mixer dispenser actuated with solenoids to keep things simple. Drink selection and control is via a touch screen, with sliders for selecting preferences such as alcohol content and sweetness.

The bartender is certainly capable of producing a neat drink (pun intended), and serves as a great example of how easily a project can be put together with industrial-grade hardware. If you’ve got the budget, you might find using an industrial plug-and-play components quicker than assembling development boards, motor controller shields and other accessories on breakout boards. There’s always more than one way to get the job done, after all.

We’ve seen some great barbots over the years, from builds relying on robotic arms to those focused on ultimate speed. Video after the break.

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Random Robot Makes Random Art

May 14, 2021 by Bryan Cockfield 4 Comments

For the price of a toothbrush and a small motor with an offset weight, a bristlebot is essentially the cheapest robot that can be built. The motor shakes the toothbrush and the bristle pattern allows the robot to move, albeit in a completely random pattern. While this might not seem like a true robot that can interact with its environment in any meaningful way, [scanlime] shows just how versatile this robot – which appears to only move randomly – can actually be used to make art in non-random ways.

Instead of using a single bristlebot for the project, three of them are built into one 3D printed flexible case where each are offset by 120°, and which can hold a pen in the opening in the center. This allows them to have some control on the robot’s direction of movement. From there, custom software attempts to wrangle the randomness of the bristlebot to produce a given image. Of course, as a bristlebot it is easily subjected to the whims of its external environment such as the leveling of the table and even the small force exerted by the power/communications tether.

With some iterations of the design such as modifying the arms and control systems, she has an interesting art-producing robot that is fairly reliable for its inherently random movements. For those who want to give something like this a try, the code for running the robot and CAD files for 3D printing the parts are all available on the project’s GitHub page. If you’re looking for other bristlebot-style robots that do more than wander around a desktop, be sure to take a look at this line-following bristlebot too.

Thanks to [johnowhitaker] for the tip!

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Leap Motion Controls Hands With No Glove

May 8, 2021 by Al Williams No comments

It isn’t uncommon to see a robot hand-controlled with a glove to mimic a user’s motion. [All Parts Combined] has a different method. Using a Leap Motion controller, he can record hand motions with no glove and then play them back to the robot hand at will. You can see the project in the video, below.

The project seems straightforward enough, but apparently, the Leap documentation isn’t the best. Since he worked it out, though, you might find the code useful.

An 8266 runs everything, although you could probably get by with less. The Leap provides more data than the hand has servos, so there was a bit of algorithm development.

We picked up a few tips about building flexible fingers using heated vinyl tubing. Never know when that’s going to come in handy — no pun intended. The cardboard construction isn’t going to be pretty, but a glove cover works well. You could probably 3D print something, too.

The Unity app will drive the hand live or can playback one of the five recorded routines. You can see how the record and playback work on the video.

This reminded us of another robot hand project, this one 3D printed. We’ve seen more traditional robot arms moving with a Leap before, too. Continue reading “Leap Motion Controls Hands With No Glove” →

MIT’s Hair-Brushing Robot Untangles Difficult Robotics Problem

May 8, 2021 by Kristina Panos 12 Comments

Whether you care to admit it or not, hair is important to self-image, and not being able to deal with it yourself feels like a real loss of independence. To help people with limited mobility, researchers at MIT CSAIL have created a hair-brushing robot that combines a camera with force feedback and closed-loop control to adjust to any hair type from straight to curly on the fly. They achieved this by examining hair as double helices of soft fibers and developed a mathematical model to untangle them much like a human would — by working from the bottom up.

It may look like a hairbrush strapped to a robot arm, but there’s more to it than that. Before it ever starts brushing, the robot’s camera takes a picture that gets cropped down to a rectangle of pure hair data. This image is converted to grayscale, and then the program analyzes the x/y image gradients. The straighter the hair, the more edges it has in the x-direction, whereas curly hair is more evenly distributed. Finally, the program computes the ratio of straightness to curliness, and uses this number to set the pain threshold.

The brush is equipped with sensors that measure the forces being exerted on the hair and scalp as it’s being brushed, and compares this input to a baseline established by a human who used it to brush their own hair. We think it would be awesome if the robot could grasp the section of hair first so the person can’t feel the pull against their scalp, and start by brushing out the ends before brushing from the scalp down, but we admit that would be asking a lot. Maybe they could get it to respond to exclamations like ‘ow’ and ‘ouch’. Human trials are still in the works. For now, watch it gently brush out various wigs after the break.

Even though we have wavy hair that tangles quite easily, we would probably let this robot brush our hair. But this haircut robot? We’re not that brave.

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Building A Robotic Band To Make Up For Lack Of Practice

May 6, 2021 by Danie Conradie 6 Comments

Learning to play a musical instrument well requires a significant time investment. [Ivan Miranda] had dreamt of doing this but made peace with the fact that his talents and motivation lay in building machines. However, he has decided to play to his strengths and is building a robotic band. See the videos after the break.

So far he has mechanized a hi-hat, snare drum, and a very basic guitar. The guitar is nothing more than a single string stretched across an aluminum frame, with an electronic pickup. Most of the work has gone into the solenoid-driven picking mechanism. He wanted to avoid picking the string when the solenoid is turned of, so he created a simple little mechanism that only comes in contact with the string when it’s moving in one direction. A bistable solenoid might be a simpler option here.

For the high hat, [Ivan] built a custom stand with two bistable solenoids to lift and drop the top cymbal. A solenoid-driven drumstick was also added. The snare drum uses a similar mechanism, but with a larger solenoid. So far he hasn’t really worked on a control system, focusing mainly on electronics.

[Ivan] points out several times that he has knows very little about making music, but we do enjoy watching him explore and experiment with this new world. Usually, his projects involve a lot more 3D printing, like when he built a giant nerf bazooka or a massive 3D printed tank. Continue reading “Building A Robotic Band To Make Up For Lack Of Practice” →

Prioritising Mechanical Multiplexer

May 4, 2021 by Danie Conradie 17 Comments

When automating almost any moderately complex mechanical task, the actuators and drive electronics can get expensive quickly. Rather than using an actuator for every motion, mechanical multiplexing might be an option. [James Bruton] has considered using it in some of his many robotics projects, so he built a prioritizing mechanical multiplexer to demonstrate the concept.

The basic idea is to have a single actuator and dynamically switch between different outputs. For his demonstration, [James] used a motor mounted on a moving platform actuated by a lead screw that can engage a number of different output gears. Each output turns a dial, and the goal is to match the position of the dial to the position of a potentiometer. The “prioritizing” part comes in where a number of outputs need to be adjusted, and the system must choose which to do first. This quickly turns into a task scheduling problem, since there are a number of factors that can be used to determine the priority. See the video after the break to see different algorithms in action.

Instead of moving the actuator, all the outputs can connect to a single main shaft via clutches as required. Possible use cases for mechanical multiplexers include dispensing machines and production line automation. Apparently, the Armatron robotic arm sold by Radioshack in the ’80s used a similar system, controlling all its functions with a single motor.

[James] knows or two about robotics, having built many of them over the last few years. Just take a look at OpenDog and his Start Wars robots. Continue reading “Prioritising Mechanical Multiplexer” →