Robotic Tabletop

Remember pin art? That’s the little box full of pins that you can push something into and the pins take on the shape. You usually use your hand, but any small object works (including, if you are brave enough, your face). [Sean Follmer] (formerly at the MIT Media Lab) developed the reverse of this: a surface made of pins driven by motors. Under computer control, the surface can take on shapes all by itself.

The square pins can be seen in the video below moving and manipulating blocks and using them to build structures out of the blocks. By using the right sequence of pin motions, the blocks can be flipped and even stacked. Magnetic blocks offer even more options.

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Hacklet 83 – Tiny Robot Projects

Hackers, makers, and engineers have been hacking on robot projects since the era of clockwork mechanics. Any robot is a cool project, but there is something particularly attractive about small ones. Maybe it’s the skill required to assemble them, or perhaps it’s the low-cost. Either way, there are lots of palm-sized robot projects on This week on the Hacklet, we’re going to highlight a few of them!

tinyrobot2We start with the granddaddy of them all, [shlonkin] and Tiny robot family. [Shlonkin] built line following robots that can hide under a US half-dollar coin. The robots are simple circuits – an ATtiny85 with an LED and pair of phototransistors. The code is provided both in Arduino’s wiring, and in straight C++. Two coreless motors, normally used in cell phones vibrators or quadcopters, provide the locomotion. These robots only know one thing – moving forward and following a line. They do it well though! We love this project so much that we hosted a tiny robot workshop at the 10th anniversary back in 2014.

toteWhen it comes to tiny walking robots, [Radomir Dopieralski] is the king. Many of his projects are small biped, quadruped, or even hexapod robots. He’s done things with 9 gram nano servos that we thought were impossible. Tote, an affordable spider robot, is his latest creation. Tote is a four-legged bot utilizing 12 9 gram servos. [Radomir] created a custom PCB for Tote, which acts as a carrier for its Arduino Pro Mini Brain. This robot is easily expandable – [Radomir] has experimented with the Teensy 3 series as well. Controlling the robot can be anything from an ESP8266 to an infrared remote control.

botbot[Alan Kilian] may well have the ultimate tease project with Hand-wound inductors for a tiny robot. [Alan] was using some tiny GM-10 motors on his micro-bot. The motors didn’t have inductance for the locked-antiphase drive controller. His solution was to wind some coils to provide a bit of added inductance. The mod worked, current consumption dropped from 116 ma to about 6 ma. We want to know more about that ‘bot though! It’s controlled by a Megabitty, [Monty Goodson’s] ATmega8 controller board from sometime around 2003. The lilliputian board has been very popular with the nano sumo crowd. Other than the controller, motors, and the plywood frame, [Alan] has left us guessing about his robot. If you see him, tell [Alan] to give us more info on his micro robot’s design and construction!


espbot[Ccates] jumped on the tiny robot bandwagon with Tiny wi-fi robot. Rather than go with an Arduino for control, [Ccates] grabbed the popular ESP-8266 WiFi module. The construction of the bot is inspired by [shlonkin’s] tiny robot family up above. This bot is controlled by the Xtensa processor embedded in the ESP-8266. Since it only drives forward, it only takes two GPIO pins to control the transistors driving the motors. Even the diminutive ESP-01 module has enough I/O for that. We’d love see some sensors and a full H-bridge on this micro beastie!


If you want to see more palm-sized robot projects, check out our new tiny robot projects list! These ‘bots are small, so I may have missed yours. If that’s the case, don’t be shy, just drop me a message on That’s it for this week’s Hacklet. As always, see you next week. Same hack time, same hack channel, bringing you the best of!

Harvard’s Microrobotic Lab Sinks RoboBees and Claims it was on Purpose

What do you call tiny flying robots that undoubtedly emit a buzzing noise as they pass by? Mosquitoes are universally hated, as are wasps, so the logical name is RoboBees.

The Wyss Institute for Biologically Inspired Engineering at Harvard University has been cooking up these extremely impressive tiny robots in their Microrobotics lab. The swarms use piezoelectric actuators to produce the mechanical force to drive the wings, which can be independently controlled.This isn’t the first time we’ve looked in on the Robobees, but the most recent news revealed the ability to swim, and dive (term used generously) into water.

This may not sound like much, but previously the robots lacked the ability to break the surface tension of water. To sink, the wings need a coating of surfactant. Once submerged, the bots lack the ability to transition back from water to air. But we won’t be surprised to see that ability added as a feature while the scope of the project continues to creep. So yes, you can jump into water to escape bees but not to escape Robobees.

Diving isn’t the only wonder to behold. The ‘head’ of the RoboBee is utterly fascinating. It’s constructed by folding the PCB into a pyramid like structure, 4 sides of the head include a photo-transistor covered by a diffused lens which the bot uses for self positioning by sensing changes between the bright light of the sky and absence thereof below the horizon. This concept is taken directly from biological self-righting systems found on the head of most insects, however Harvard’s version has one more sensor than the stock 3 seen on insects. Take that, nature!

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Hand Controlled Robot uses Accelerometer

What do orchestra conductors, wizards, and Leap controller users have in common? They all control things by just waving their hands. [Saddam] must have wanted the same effect, so he created a robot that he controls over wireless using hand gestures.

An accelerometer reads hand motions and sends them via an RF module to an Arduino. This is a bit of a trick, because the device produces an analog value and [Saddam] uses some comparators to digitize the signal for the RF transmitter. There is no Arduino or other CPU on the transmit side (other than whatever is in the RF module).

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Talk To The (Robotic) Hand

Robotic hacker [Andrea Trufini] apparently likes choices. Not only does his robotic arm have six degrees of freedom, but it has a variety of ways he can control it. The arm’s software can accept commands through a programming language, via potentiometers, an infrared remote, or–the really interesting part–through spoken commands.

The videos don’t show too much of the build detail, but the arm is mainly constructed of laser cut plywood and uses an Arduino. Hopefully, we’ll see more particulars about the build soon but for now have a look at a similar project.

The software (myrobotlab) is on github and looks very impressive. The Java-based framework has a service-oriented architecture, with modules that support common processors (like the Arduino, Raspberry Pi, and Beagle Board) along with I/O devices (like motors, sound devices, and that Leap Motion controller you just had to buy). As you might expect from the demonstration found below, there are speech to text and text to speech services, too. Like a lot of open source projects, some of these services are more ready for prime time than others but that just means you can contribute your hacks back to the project.

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My Robot Army @ Maker Faire

For a few years now I’ve been developing an interactive army of delta robots. This ongoing project is fueled by my desire to control many mechanical extremities like an extension of my body (I’m assuming I’m not the only one who fantasizes about robots here).

IMG_1846Since my army doesn’t have a practical application… other than producing pretty light patterns and making the user feel extremely cool for a minute, I guess you’d call it art. In the past I’ve held a Kickstarter to fund the production of my art which I can now happily show at cool events with interesting people; Maker Faire being one of them.

Interactivity and Sprawling Crowds

Last year, for our debut at the big Bay Area Maker Faire, my collaborator, [Mark], and I displayed a smaller sampling of 30 robots for our installation. We also decided to create an interactive aspect for others to experience. After the end of our crowdfunding period last March, we had a little over a month to do any development before the big event, so our options were slim. The easy solution was to jam our delta code into the hand tracking demo which comes with the Xbox Kinect’s Open NI within Processing. This was cool enough to exhibit, but we hadn’t really anticipated how it would go over in an environment as densely packed as the dark room at Maker Faire.

We should have known better. Both of us were aware that there would be many, many children… all with micro hands to confuse and bewilder the Kinect, but we did it anyway. Our only resolve was to implement the feature that would force the Kinect to track one hand at a time, only after being waved at in a very particular fashion. After needing to explain this stipulation to every person who stopped by our booth over the course of the weekend, we decided never to use the Kinect for crowds ever again; lesson learned.

Delta Robots and DMX

Over the past year since that experience, we’ve tripled the size of the installation and brainstormed some better demo ideas. As of now, the robots are all individually addressable over an RS485 bus, and we use the DMX protocol over a CAT5 cable to send commands. If you aren’t familiar with it, DMX is used in show production to control stage lighting… to which there is a super neat and free application called QLC+ that allows you to effectively orchestrate the motion and color of many individual light units; perfect for our cause.

qlcDeltasFunctionally, each of the 84 delta robots in the installation believes that it is a stage light (robots with identity issues). We mapped the X and Y axis of the end effector to the existing pan and tilt values, and the z axis to the beam focus value. The RGB of the LED mounted in the end effector of each delta maps directly to the RGB value of the stage light.

By using the sliders in the QLC+ GUI, I could select groups of robots and create presets for position and color. This was great, someone like me who doesn’t really write a lot of code could whip up impressive choreography with little sweat. Additionally, the program comes with a nice visualizer, where you can layout virtual nodes and view your effects as you develop them.

This is the layout of our installation mapped in QLC+. The teal and purple sliders around each light represent pan and tilt (or in our case X and Y):


Lighting control was an interesting solution. Having autonomous robots this year changed how people responded to them, as they were less like an army you’d command and more of a hypnotic field of glowing grass.

[Mark] and I are considering picking up some flex sensors and maybe playing with the Leap or an EEG headset as a means to reintroduce the interactive aspect. Bottom line, I have this cool new toy that I can’t wait to play with over the summer!

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Twisted String Actuators

[Travis] tells us about a neat actuator concept that’s as old as dirt. It’s capable of lifting 7kg when powered by a pager motor, and the only real component is a piece of string.

The concept behind the twisted string actuator, as it’s known to academia, is as simple as putting a motor on one end of a piece of string, tying the other end off to a load, and putting a few twists in the string. It’s an amazingly simple concept that has been known and used for thousands of years: ballistas and bow-string fire starters use the same theory.

Although the concept of a twisted string actuator is intuitively known by anyone over the age of six, there aren’t many studies and even fewer projects that use this extremely high gear ratio, low power, and very cheap form of linear motion. A study from 2012 (PDF) put some empirical data behind this simple device. The takeaway from this study is that tension on the string doesn’t matter, and more strands or larger diameter strands means the actuator shrinks with a fewer number of turns. Fewer strands and smaller diameter strands take more turns to shrink to the same length.

As for useful applications of these twisted string actuators, there are a few projects that have used these systems in anthropomorphic hands and elbows. No surprise there, really; strings don’t take up much space, and they work just like muscles and tendons do in the human body.

Thanks [ar0cketman] for the link.