Cat-Operated Cat Food Dispenser

Tired of being harassed by your cat? [MomWillBeProud] made a cheap, effective — and more importantly cat-operated — cat food dispenser.

The feeder is of an efficient construction — a double cat food dish, one container to store the electronics, and a Pringles can to act as the hopper. A simple servo rotates the hopper thirty degrees and back on each button press; using gravity to drop food through an opening that appears due to this motion. The button itself is an old IKEA timer and a piece of plastic large enough for a hungry cat to swat.

An Arduino controls the servo, and while [MomWillBeProud] skips over going into detail on his code, you can check it out here.

Continue reading “Cat-Operated Cat Food Dispenser”

Arduino Absentmindedly Blows Bubbles

If you ever wanted to make an occasion festive with bubbles, [Sandeep_UNO] may have the project for you. As you can see in the video below (and, yes, it should have the phone rotated and it doesn’t), his Arduino uses a servo motor to dip a bubble wand into soap solution and then pulls it in front of a fan. The entire operation repeats over and over again.

There’s not a lot of detail and no code that we could find, but honestly, if you know how to drive a servo motor from an Arduino, the rest is pretty easy to figure out. Look closely at the motion of the robot. What is often accomplished with a spinning wheel of bubble wands and a constant fan becomes much more interesting when applied intermittently. The lazy cadence is what you expect to see from human operation and that adds something to the effect.

We’ve seen faster bubble blowers, but they were not so simple. We’ve even looked at other bubble-blowing robots. If you want to find out more about servo motors in general, our own [Richard Bauguley] has what you need to know.

Continue reading “Arduino Absentmindedly Blows Bubbles”

A Pi Robot Without a Hat

Daughter boards for microcontroller systems, whether they are shields, hats, feathers, capes, or whatever, are a convenient way to add sensors and controllers. Well, most of the time they are until challenges arise trying to stack multiple boards. Then you find the board you want to be mid-stack doesn’t have stackable headers, the top LCD board blocks the RF from a lower board, and extra headers are needed to provide clearance for the cabling to the servos, motors, and inputs. Then you find some boards try to use the pins for different purposes. Software gets into the act when support libraries want to use the same timer or other resources for different purposes. It can become a mess.

The alternative is to unstack the stack and use external boards. I took this approach in 2013 for a robotics competition. The computer on the robots was an ITX system which precluded using daughter boards, and USB ports were my interface of choice. I used a servo controller and two motor controllers from Pololu. They are still available and I’m using them on a rebuild, this time using the Raspberry Pi as the brain. USB isn’t the only option, though. A quick search found boards at Adafruit, Robotshop, and Sparkfun that use I2C.

Continue reading “A Pi Robot Without a Hat”

Venduino Serves Snacks, Shows Vending is Tricky Business

Seems like just about every hackerspace eventually ends up with an old vending machine that gets hacked and modded to serve up parts, tools, and consumables. But why don’t more hackerspaces build their own vending machines from scratch? Because as [Ryan Bates] found out, building a DIY vending machine isn’t as easy as it looks.

[Ryan]’s “Venduino” has a lot of hackerspace standard components – laser-cut birch plywood case, Parallax continuous rotation servos, an LCD screen from an old Nokia phone, and of course an Arduino. The design is simple, but the devil is in the details. The machine makes no attempt to validate the coins going into it, the product augurs are not quite optimized to dispense reliably, and the whole machine can be cleaned out of product with a few quick shakes. Granted, [Ryan] isn’t trying to build a reliable money-making machine, but his travails only underscore the quality engineering behind modern vending machines. It might not seem like it when your Cheetos are dangling from the end of an auger, but think about how many successful transactions the real things process in an environment with a lot of variables.

Of course, every failure mode is just something to improve in the next version, but as it is this is still a neat project with some great ideas. If you’re more interested in the workings of commercial machines, check out our posts on listening in on vending machine comms or a Tweeting vending machine.

Continue reading “Venduino Serves Snacks, Shows Vending is Tricky Business”

Wireless Robotic Gripper With Haptic Feedback

We’re not sure what kind of, “High School,” [Sam Baumgarten] and [Graham Hughes] go to that gave them the tools to execute their robotic gripper so well. We do know that it was not like ours. Apparently some high schools have SLS 3D printers and Solidworks. Rather than a grumpy shop teacher with three fingers who, despite that, kept taking the safety off the table saws and taught drafting on boards with so many phalluses and names carved into the linoleum, half the challenge was not transferring them to the line work.

Our bitterness aside, [Sam] and [Graham] built a pretty dang impressive robotic gripper. In fact, after stalking [Sam]’s linkedin to figure out if he was the teacher or the student, (student) we decided they’re bright enough they could probably have built it out of scraps in a cave. Just like [HomoFaciens], and Ironman.

The gripper itself is three large hobby servos joined to the fingers with a linkage, all 3D printed. The mechanical fingers have force sensors at the contact points and the control glove has tiny vibrating motors at the fingertips. When the force of the grip goes up the motors vibrate more strongly, providing useful feedback. In the video below you can see them performing quite a bunch of fairly fine motor skills with the gripper.

The gripper is mounted on a pole with some abrasive tape, the kind found on skateboard decks. At the back of the pole, the electronics and batteries live inside a project box. This provides a counterbalance to the weight of the hand.

The control glove has flexible resistors on the backs of the fingers. The signal from these are processed by an Arduino which transmits to its  partner arduino in the gipper via an Xbee module.

[Sam] and [Graham] did a great job. They worked through all the design stages seen in professional work today. Starting with a napkin sketch they moved onto digital prototyping and finally ended up with an assembly that worked as planned. A video after the break explaining how it works along with a demo video.

Continue reading “Wireless Robotic Gripper With Haptic Feedback”

Hacklet 113 – New Robots

I start each day checking out the new and updated projects over on Each day one can find all manner of projects – from satellites to machine vision to rockets. One type of project which is always present are robots- robot arms, educational ‘bots, autonomous robots, and mobile robots. This week’s had a few great robot projects show up on the “new and updated” page, so I’m using the Hacklet to take a closer look.

bot1We start with [Jack Qiao] and Autonomous home robot that does things. [Jack] is building a robot that can navigate his home. He’s learned that just creating a robot that can get itself from point A to point B in the average home is a daunting task. To make this happen, he’s using the Simultaneous Localization and Mapping (SLAM) algorithm. He’s implementing SLAM with the help of Robotic Operating System (ROS).  The robot started out as a test mule tethered to a laptop. It’s evolved to a wooden base with a mini ITX motherboard. Mapping data comes in through a Kinect V2, which will soon be upgraded to a Neato XV-11 LIDAR system.


tyrobotNext up is [Tyler Spadgenske] with TyroBot. TyroBot is a walking robot with some lofty goals, including walking a mile in a straight line without falling down. [Tyler’s] inspiration comes from robots such as Bob the Biped and Zowi. So far, TyroBot consists of legs and feet printed in PLA. [Tyler] is going to use a 32 bit processor for [TyroBot’s] brain, and wants to avoid the Arduino IDE at any cost (including writing his own IDE from scratch). This project is just getting started, so head on over to the project page and watch TyroBot’s progress!


friendbotNext is [Mike Rigsby] with Little Friend. Little Friend is a companion robot. [Mike] found that robots spend more time charging batteries than interacting. This wouldn’t do for a companion robot. His solution was to do away with batteries all together. Little Friend is powered by super capacitors. An 8 minute charge will keep this little bot going for 75 minutes. An Arduino with a motor shield controls Little Friend’s DC drive motors, as well as two animated eyes. If you can’t tell, [Mike] used a tomato as his inspiration. This keeps Little Friend in the cute zone, far away from the uncanny valley.


logi-botFinally we have the walking robot king, [Radomir Dopieralski], with Logicoma-kun. For the uninitiated, a Logicoma is a robot tank (or “logistics robot”) from the Ghost in the Shell series. [Radomir] decided to bring these cartoon tanks to life – at least in miniature. The bulk of Logicoma-kun is built carefully cut and sculpted acrylic sheet. Movement is via popular 9 gram servos found all over the internet. [Radomir] recently wrote an update outlining his new brain for Logicoma-kun. An Arduino Pro Mini will handle servo control. The main computer will be an ESP8266 running Micropython. I can’t wait to see this little ‘bot take its first steps.

If you want more robotic goodness, check out our brand new mobile robot list! Did I miss your project? 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!

Arduino Meets da Vinci in a Gesture-controlled Surgical Robot

Lots of us get to take home a little e-waste from work once in a while to feed our hacking habits. But some guys have all the luck and score the really good stuff, which is how these robotic surgical tools came to be gesture controlled.

The lucky and resourceful hacker in this case is one [Julien Schuermans], who managed to take home pieces of a multi-million dollar da Vinci Si surgical robot. Before anyone cries “larcency”, [Julien] appears to have come by the hardware legitimately – the wrist units of these robots are consumable parts costing about $2500 each, and are disposed of after 10 procedures. The video below makes it clear how they interface with the robot arm, and how [Julien] brought them to life in his shop. A quartet of Arduino-controlled servos engages drive pins on the wrist and rotates pulleys that move the cables that drive the instruments. A neat trick by itself, but when coupled with the Leap Motion controller, the instruments become gesture controlled. We’re very sure we’d prefer the surgeon’s hands on a physical controller, but the virtual control is surprisingly responsive and looks like a lot of fun.

When we talk about da Vinci around here, it’s usually in reference to 3D printers or a Renaissance-style cryptex build. Unsurprisingly, we haven’t featured many surgical robot hacks – maybe it’s time we started.

Continue reading “Arduino Meets da Vinci in a Gesture-controlled Surgical Robot”