Robot Servo Control Using Smartphone Audio Jack

August 14, 2012 by Mike Szczys 10 Comments

[Jim] has an old Android phone he’d like to use as a Robot brain. It’s got a lot of the things you’d want in a robot platform; WiFi, Bluetooth, a camera, an accelerometer, etc. But he needed some way to make the mobile, mobile. What he came up with is a chassis with servos that can be controlled by the phone’s audio port.

To start his adventure he crafted a square wave audio file in Audacity and then played it back on the Android music player. By monitoring the output on an oscilloscope he found the wave was well produced, with peaks of about 1V. With that in mind he designed a circuit using two transistors to amplify the signal, thereby creating a usable input for the servo motors. Each motor has one of these circuits connected to it, with the left and right channels from the audio jack driving them separately. In the clip after the break you can see he even wrote a simple Android app to extend the idea to a more usable level.

This is a similar technique as used by the recon robot we saw about a year ago.

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Servos, Servos, And More Servos

July 21, 2012 by Brian Benchoff 22 Comments

For one reason or another, a lot of Hackaday readers are doing stuff with servos as of late. Here’s a few servo hacks that made their way into our tip line over the past day or so:

USB servo controller and a Stewart Platform

[Patricio] needed a way to control a bunch of servos for his thesis project. He came up with a USB servo controller (Spanish, here’s the translation) powered by a 40-pin PIC 18F microcontroller. The board connects to the USB port of a computer and supports up to 8 servos with 8 additional digital I/Os. Why all this horsepower? It’s for a Stewart Platform [Patricio] and his partner [Natalia] built.

Continuous rotation servos

Standard servos are usually limited to a rotation angle of somewhere between 140 and 160 degrees. Sometimes you need a continuous rotation servo, and those are a little more expensive. Every servo is a continuous rotation servo if you disable a the variable resistor as [Valentin] shows us. It’s a simple, if old, hack. It’s new to someone, though.

Eight servos on a Raspi

[Mikael] made a little board to attach to the GPIO header of his Raspberry Pi and control up to 8 servos. The board is running a serial interface with a small microcontroller on board. There’s nothing in the way of schematics or code, a testament for why you should always use a good email address when sending something into the HaD tip line. It seems [Mikael] is making a proper board, and we’ll more than happily give it a full post when it’s complete.

Laser Light Painting Includes Camera Control

July 13, 2012 by Mike Szczys 6 Comments

This laser light painting setup can even control the camera. But it probably will not work with your average point-and-shoot. The exposure time used is somewhere around 2 seconds long, a feature which is hard to find on anything but DSLR cameras.

The setup relies on a red laser diode to do the painting. When viewed in real time you only see a dot tracing out a cryptic pattern and occasionally switching on and off. But with a long exposure the intense light persists to achieve an image like the one seen above. Note the ghosting around the rig as it has moved while the shutter was open.

The Arduino controlled device consists of a base which pivots the diode horizontally, with a servo for aiming on the vertical axis. Since the sketch is divided up by letter, we wonder how hard it would be to adapt this for use with a point-and-shoot? Perhaps you could capture one letter at a time and layer the frames in post production?

It seems this is a lot easier to build than some of the LED plotters we’ve looked at. If you do make your own don’t forget to send a link our way.

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Digital Picture Frame That Rotates To Match Image Orientation

July 12, 2012 by Mike Szczys 7 Comments

This digital picture frame physically rotates in order to match the image’s orientation. [Markus Gritsch] built the frame, including a Python script to translate the photos to a format which makes the best use of the 2.4″ LCD screen.

The screen is addressed in 8-bit parallel by a PIC 32MX120F032B processor. Image are read from an SD card in a raw format, with 16-bit colors pushed to the display for each pixel. To get them into this format [Markus’] script converts the JPEG files to RAW, resizes them, uses dithering to reduce to 16-bit color, then applies a sharpening filter to improve the final look. During this process it also includes orientation information. That is parsed by the microcontroller and used to drive the servo motor to which the screen is attached.

To finish off the project he spray painted a piece of acrylic to act as a bezel for the frame. Check out the demo after the break and we think you’ll agree the rotating feature, along with image scrolling, really makes this a piece you’ll want on your own desk.

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Adding A Bomb Bay To A Quadcopter

July 2, 2012 by Brian Benchoff 24 Comments

The Fourth of July is fast approaching, and what better way to celebrate the independence of your country than by blowing up a small piece of it? [Anzel360] decided to take that line of thought to a whole new level by adding a bomb bay to his quadrocopter.

[Anzel360] recently upgraded his transmitter to a Spektrum DX8, giving him two extra channels on his four-channel quadrotor. After adding a small servo to the quad, it was a simple matter of taping a box to the undercarriage and filling it full of fireworks.

The ammo [Anzel] is using is just a handful of Snappin’ Pops – otherwise known as the lamest firework ever created. We won’t hold that against him, though; a remote ignition system for a few Black Cats mounted on a fancy quadrocopter is just asking for trouble. We do recall a throwable cap gun bomb from our youth, though, that would allow for year-round ammo replenishment…

Robot Dares You To Snatch The Pebble From This Flower

June 29, 2012 by Mike Szczys 27 Comments

This pleasant-looking plant may try to take your hand off if you’re not careful. The robot flower (translated) includes sensors that cause the petals to move in reaction to external stimuli.

You can just make out the distance sensors as black rectangles on two of the petals. These let the flower track an object by rotating the flower stem. But if they determine the object is getting a bit too close for comfort, the servo motor on the back of each petal will cause the flower to suddenly clamp shut.

The video after the break starts off with an in-depth look at the hardware that went into the project. An Arduino clone called the GRoboduino makes this project a lot easier since it has a bunch of extras on the board aimed at things like sensors and servo motors. The mounting technique for the petal-powering-servos is quite attractive, and we enjoy the Snapple lid (probably not the actual brand but you get the picture) which has been coated with yellow felt for the center of the bloom. The final look is normal enough to fit in with home decor, but it still has enough geek in it to melt our hacker hearts.

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Head-mounted Memory Catcher

June 21, 2012 by Mike Szczys 20 Comments

A picture’s worth a thousand words so what is a hat that can take 360 degree pictures worth? Just make sure you put it on whenever leaving the house and capturing that next memorable moment will be just one click of a button away.

[Mikeasaurus] recently put together this… special… headgear. He used film-based disposable cameras and this choice presented a few interesting challenges. But the choice is not necessarily a bad one, as you can get six of these without really blowing your budget. He cut the top off of a plastic garbage can to serve as a headband on which to mount the hardware (zip-ties to the rescue). But things get hairy when it comes to triggering all of the shutters at once. These are spring-loaded shutter releases and you can’t just patch into them electrically like you could a digital camera. His solution is a group of six servo motors which do the button pushing for him.

A thirty-six exposure trial run turned out okay. Several times the shots didn’t come out, but at the end of his post he shares a few of the good ones that did. We’re going to stear clear of this one as we can’t abide manually winding all six cameras between each shot. But it does give us an idea for a single-camera hat that uses a 45-degree mirror which swivels. We’ll just put that one in the growing pile of ideas we need to make time for.