ServoBender, The Electronic Pedal Steel

July 9, 2014 by Brian Benchoff 39 Comments

You’ve most certainly heard a pedal steel guitar before, most likely in any ‘old’ country song, or more specifically, any country song that doesn’t include the word ‘truck’ in its lyrics. Pedal steels are strange devices, looking somewhat like a 10-string guitar with levers that change the pitch of individual strings. Historically, there have been some attempts to put a detuning mechanism for individual strings in normal electric guitars, but these are somewhat rare and weird. [Gr4yhound] just nailed it. He’s come up with the perfect device to emulate a pedal steel in a real guitar, and it sounds really, really good.

The imgur album for this project goes over the construction of the ServoBender in a bit more detail than the video. Basically, four servos are mounted to a metal plate below the bridge. Each servo has a spring and cam system constructed out of 3D printed parts. The detuning is controlled by an Arduino and a few sustain pedals retrofitted with hall effect sensors. Simple, really, but the effect is astonishing.

[Gra4hound]’s contraption is actually very similar to a B-Bender where a guitarist pushes on the neck to raise the pitch of the B string. This setup, though, is completely electronic, infinitely adjustable, and can be expanded to all six strings. Very, very cool, and it makes us wonder what could be done with one of those freaky robot guitars, a soldering iron, and a bit of code.

Video below, because you should watch it again.

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Attiny PWM Generator And Servo Tester

June 8, 2014 by Nick Conn 21 Comments

PWM-Servo-Tester

Having the right tool for the job makes all the difference, especially for the types of projects we feature here at Hackaday. [Jana Marie] must agree with this sentiment, one of her latest projects involves building a tool to generate a PWM signal and test servos using an Attiny25/45/85.

Tools come in all kinds of different shapes and sizes. Even if it might not be as widely used as [Jana’s] earlier work that combines an oscilloscope and signal generator, having a tool that you can rely upon to test servos and generate a PWM can be very useful. This well written Instructable provides all the details you need to build your own, including the schematic and the necessary code (available on GitHub). The final PWM generator looks great. For simple projects, sometimes a protoboard is all you need. It would be very cool to see a custom PCB made for this project in the future.

What tools have you build recently? Indeed, there is a tool for every problem. Think outside the (tool) box and let us know what you have made!

The Un-Digital Robotic Arm

June 3, 2014 by Brian Benchoff 23 Comments

556 When you think of a robotic arm, you’re probably thinking about digital control, microcontrollers, motor drivers, and possibly a feedback loop. Anyone who was lucky enough to have an Armatron knows this isn’t the case, but you’d still be surprised at how minimal a robotic arm can be.

[viswesh713] built a servo-powered robotic arm without a microcontroller, and with some interpretations, no digital control at all. Servos are controlled by PWM signals, with a 1 ms pulse rotating the shaft one way and a 2 ms pulse rotating the shaft the other way. What’s a cheap, popular chip that can easily be configured as a timer? Yep, the venerable 555.

The robotic arm is actually configured more like a Waldo with a master slave configuration. [viswesh] built a second arm with pots at the hinges, with the resistance of the pots controlling the signal output from a 556 dual timer chip. It’s extremely clever, at least until you realize this is how very early robotic actuators were controlled. Still, an impressive display of what can be done with a simple 555. Videos below.

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Servo Stock, The Future Of 3D Printers

May 26, 2014 by Brian Benchoff 101 Comments

printer If you think about it, the RepRaps and other commercial 3D printers we have today are nothing like the printers that will be found in the workshops of the future. They’re more expensive than they need to be, and despite the RepRap project being around for a few years now, no one has cracked the nut of closed loop control yet. [mad hephaestus], [Alex], and [Will] over on the Hackaday Projects site are working on the future of 3D printing with the Servo Stock, a delta printer using servos and closed loop control to build a printer for about a quarter of the price as a traditional 3D printer.

The printer itself is a Kossel derivative that is highly modified to show off some interesting tech. Instead of steppers, the printer has three axes controlled by servos. On each axis is a small board containing a magnetic encoder, and a continuous rotation servo. With this setup, the guys are able to get 4096 steps per revolution with closed loop control that can drive the servo to with ±2 ticks.

The electronics and firmware are a clean sheet redesign of the usual 3D printer loadout. The motherboard uses a Pic32 running at 80MHz. Even the communication between the host and printer has been completely redesigned. Instead of Gcode, the team is using the Bowler protocol, a system of sending packets over serial, TCP/IP, or just about any other communications protocol you can think of.

Below is a video of the ServoStock interpreting Gcode on a computer and sending the codes and kinematics to the printer. It seems to work well, and using cheap servos and cut down electronics means this project might just be the first to break the $200 barrier for a ready to run 3D printer.

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Roboartist Draws What It Sees

April 28, 2014 by Mike Szczys 10 Comments

roboartist-vector-image-machine

The perfect balance of simplicity and complexity have been struck with this automated artist. The Roboartist is a vector drawing robot project which [Niazangels], [Maxarjun], and [Ashwin] have been documenting for the last few days. The killer feature of the build is the ability to process what is seen through a webcam so that it may be sketched as ink on paper by the robotic arm.

The arm itself has four stages, and as you can see in the video below, remarkably little slop. The remaining slight wiggle is just enough to make the images seem as if they were not printed to perfection, and we like that effect!

Above is a still of Roboartist working on a portrait of [Heath Ledger] in his role as Joker from The Dark Knight. The image import feature was used for this. It runs a tweaked version of the Canny Edge Detector to determine where the pen strokes go. This is an alternative to capturing the subject through the webcam. For now MATLAB is part of the software chain, but future work seeks to upgrade to more Open Source tools. The hardware itself uses an Arduino Mega to take input via USB or Bluetooth and drives the quartet of servo motors accordingly.

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Tricked-out Arduino-controlled Time-Lapse Is More Than Just A Timer

December 16, 2013 by Kristina Panos 1 Comment

arduinoPhotoRig

[Hlesliebole] wanted a finer degree of remote control over his time-lapse shots, so he decided to build an Arduino-driven infrared shutter. He ended up creating this killer Arduino-controlled photography rig that does a whole lot more.

This hack was built for [Hlesliebole]’s Nikon D3100, but he says it should work with any DSLR and remote shutter. This initial build uses an LED as a stand-in for the remote shutter that he ordered. He intends to update the post once it arrives and he integrates it.

[Hlesliebole] wired a 7-segment display to show the current time delay between photos. This can be set on the fly with a potentiometer, so there’s no need to stop and reprogram the Arduino. And while you’re grabbing a beer and watching the sun slowly sink, the rig can better capture that sunset because of a photoresistor. It detects the ambient light level and minimizes the number of throwaway dark shots.

If that weren’t enough, he’s built servo functionality into the code to support remote control over the camera’s physical position, allowing for panning or rotation over a scene. [Hlesliebole] doesn’t go into detail, but he assures us that there are many tutorials out there. If you think you’re man enough, you could always work in this outstanding versatile motion dolly hack.

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Hack-a-Day Logo Laser Light Show

November 24, 2013 by Todd Harrison No comments

The Hack-a-Day logo challenge keeps on bearing fruit. This tip comes from [Enrico Lamperti] from Argentina who posted his follies as well as success creating a Hack-a-Day logo using a home built scanning laser projector.

The build consists of a couple small servos, a hacked up pen laser and an Arduino with some stored coordinates to draw out the image. As usual the first challenge is powering your external peripheral devices like servos. [Enrico] tackled this problem using 6 Ni-MH batteries and an LM2956 simple switcher power converter. The servos and Arduino get power directly from the battery pack and the Arduino controls the PWM signals to the servos as they trace out the stored coordinate data. The laser is connected to the servo assembly and is engaged and powered by an Arduino pin via an NPN transistor. He also incorporated a potentiometer to adjust the servo calibration point.

His first imported coordinate data generated from some Python script was not very successful. But later he used processing with an SVG file to process a click-made path the Arduino could use as map data to draw the Hack-a-Day logo. It requires a long exposure time to photograph the completed drawing in a dark room but the results are impressive.

It’s an excellent project where [Enrico] shares what he learned about using Servo.writeMicroseconds() instead of Servo.write() for performance along with several other tweaks. He also shared the BOM, Fritzing diagram, Processing Creator and Simulator tools and serial commands on GitHub. He wraps up with some options that he thinks would improve his device, and he requests any help others may want to provide for better performance. And if you want you could step it up a notch and create a laser video projector with an ATMega16 AVR microcontroller and some clever spinning tilted mirrors.