Grow Your Own Tin Crystals

June 13, 2017 by John Baichtal 16 Comments

[The Plutonium Bunny] saw homegrown tin crystals on YouTube and reckoned he could do better—those crystals were flimsy and couldn’t stand up outside of the solution in which they were grown. Having previously tackled copper crystals, he applied the same procedure to tin.

Beginning with a 140 ml baby food jar filled with a solution of tin II chloride, 90 grams per liter, with a small amount of HCl as the electrolyte. A wire at the bottom of the jar was connected to a blob of tin and served as the anode, while the cathode, a loop of tin, stuck down from above. A LM317-based adjustable voltage regulator circuit was used to manage the power running through the solution. Because [The Plutonium Bunny]’s technique involves days or even weeks of very low current, he used six diodes to drop the circuit’s voltage from 1.5 V to 0.25 V, giving him around 13 mA.

His first attempt seemed to go well and he got some nice shiny crystal faces, but he couldn’t get the current bellow 10 mA without it dropping to the point where no tin was depositing. Rather than reset the experiment he made some changes to the project: he changed the solution by removing 30 ml of the electrolyte and topping it off with water. He also made a gentle agitator out of a DC motor and flattened plastic tube from a pen, powering it with another low-voltage LM317 circuit so he could get the lowest RPM possible.

With this new setup [The Plutonium Bunny] began to get much better results, proving his hypothesis that low current with a lower concentration of Sn2+ was the ticket for large crystal growth. We featured his copper crystal experiments last year and he’s clearly making good progress! Video after the break.

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Universal Robots Vision-Based LEGO Stacker

June 11, 2017 by John Baichtal 2 Comments

[Thomas Kølbæk Jespersen] and his classmates at Aalborg University’s Robot Vision course used MATLAB code and URscript to program a Universal Robots UR5 to stack up Duplo bricks. The Duplo bricks are stacked into low-fi Simpsons characters — yellow for Homer’s head, white for his shirt, and blue for his pants, for example.

The bricks are scattered randomly on a nearby table, while a camera mounted above the table scans the bricks and assists in determining the location, color, and orientation of the elements. This involves blob analysis which helps the computer decide what pixel is part of a brick and what isn’t. After running a recursive grassfire algorithm with 4-connectivity, the computer gives each pixel a number and assigns it to a blob.

To determine the orientation (the bricks are all assumed to be stud-side up and not overlapping) the blob is divided into quadrants and within each quadrant, the distance between the center of the blob and its farthest pixel is measured. This technique is not likely to work as well with a brick that isn’t square. Each brick’s location in pixels is translated into Cartesian coordinates, making it a cinch for the robot to pick it up. See [Thomas]’s GitHub for MATLAB and URscript code.

Looking for more UR5 projects? Check out the Sewbo garment-making robot we published last year.

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Quality Assurance Through FPGA

June 10, 2017 by John Baichtal 13 Comments

[Claire Chen] and [Mark Zhao], students in [Bruce Land]’s ECE5760 class at Cornell, created a project aimed at the manufacturing sector: quality-checking manufactured products automatically by visually scanning a bunch of them and processing the pixels one at a time. Ordinarily, the time when the widget comes off the line is when you have to bring in actual people to inspect. This project uses morphological image processing to like dilation and erosion to look for flaws.

[Claire] and [Mark] created a simulated manufacturing line with a servo-driven belt that brings a series of Spree candies into the range of a camera, which scans them. The SoC with a Cyclone V FPGA and ARM Cortex-9 then processes the raw images to establish the object’s color, while running it through a couple of algorithms to look for defects. The FPGA tracks how many Sprees that have passed by as well as their color, maintaining a 99% success rate with a rate of 5-10 frames per second. The FPGA also looks at each blob of color as a collection of pixels, establishing connectivity to help to distinguish multiple Sprees touching each other.

Also be sure to check out [Claire] and [Mark]’s bike sonar project from a previous semester.

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The Monolith Brings The Boom To Maker Faire

June 10, 2017 by John Baichtal 4 Comments

[Ross Fish], [Darcy Neal], [Ben Davis], and [Paul Stoffregen] created “the Monolith”, an interactive synth sculpture designed to showcase capabilities of the Teensy 3.6 microcontroller.

The Monolith consists of a clear acrylic box covered in LED-lit arcade buttons. The forty buttons in front serve as an 8-step sequencer with five different voices, while touch sensors on the left and right panels serve as a polyphonic arpeggiator and preset controller, respectively.

In order to control all of those buttons, the team designed breakout boards equipped with a port expander, 16-channel PWM driver chip, and N-channel MOSFETs allowing the entire synth to be controlled from a single Teensy 3.6.

In terms of software, [Paul] made improvements to the Teensy Audio Library to accommodate the hardware, improving the way signal-controlled PWM waveforms are handled and enhancing the way envelopes work. Ultimately they combined three Arduino sketches into one to get the finished code.

After showing off the project on Tested, the team set up the Monolith in the Kickstarter booth at Maker Faire Bay Area. The project was a hit at the Faire, earning a coveted red ribbon and inspiring countless adults and kids to check it out. We love a project that inspires so much interaction. Not only can three people play with the Monolith at once, but they can see through the clear case and get an idea of what’s going on.

If you want to learn more you can download project files from [Paul]’s GitHub. In the meantime, check out some other synth projects we’ve published on Hackaday: we’ve grooved on a synth-violin, a 3D-printed synth, and a single-PCB synth, among many others.

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Visual Scanner Turns Obstacles Into Braille

June 9, 2017 by John Baichtal 8 Comments

This interesting project out of MIT aims to use technology to help visually impaired people navigate through the use of a haptic feedback belt, chest-mounted sensors, and a braille display.

The belt consists of a vibration motors controlled by what appears to be a Raspberry Pi (for the prototype anyway) with a distance sensor and camera connected as well. The core algorithm is designed to take input from the camera and distance sensors to compute the distance to obstacles, and to buzz the right motor to alert the user — fairly expected stuff. However, the project has a higher goal: to assist in identifying and using chairs.

Aiming to detect the seat and arms, the algorithm looks for three horizontal surfaces near each other, taking extra care to ensure the chair isn’t occupied. The study found that, used in conjunction with a cane, the system noticeably helped users navigate through realistic environments, as measured by minor and major collisions. Users recorded dramatically fewer collisions as compared to using the system alone or the cane alone. The project also calls for a belt-mounted braille display to relay more complicated information to the user.

We at HaD have followed along with several braille projects, including a refreshable braille display, a computer with a braille display and keyboard, and this braille printer.

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Controlling A Moog Werkstatt With A Capacitive Touch Jankó Keyboard

June 8, 2017 by John Baichtal 1 Comment

[Ben Bradley], a member of Freeside Atlanta, built a capacitive touch Jankó keyboard for the Georgia Tech Moog Hackathon. Jankó Keyboards are a 19th-Century attempt to add a more compact piano keyboard. There are three times as many keys as a traditional piano but arranged vertically for (supposedly) greater convenience while playing–an entire octave can be covered with one hand. But yeah, it never caught on.

[Ben]’s project consists of a series of brass plates wired to capacitive touch breakout boards from Adafruit, one for each of the Arduino Mega clone’s four I2C addresses. When a key is touched, the Arduino sends a key down signal to the Werkstatt while using a R-2R ladder to generate voltage for the VCO exponential input.

The most recent Moog Hackathon was the third. Twenty-five teams competed from Georgia Tech alone, plus more from other schools, working for 48 hours to build interfaces with Moog Werkstatt-Ø1 analog synths, competing for $5,000 in cash prizes as well as Werkstatts for the top three teams.

We’re synth-fiends here on Hackaday: we cover everything from analog synths to voltage controlled filters.

Via Freeside Atlanta, photo by [Nathan Burnham].

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Simulating VR Obstacles With Wheelchair Brakes

June 1, 2017 by John Baichtal 6 Comments

[Joey Campbell] is studying for his PhD at the Bristol Interaction and Graphics Lab, focusing on the interplay between real and virtual objects within the realm of exergaming–“gamercising” where physical motion and effort drives the game. The goal is to make the physical effort seem to correspond with what’s seen on the headset.

[Joey] set up a test rig where an exercise bike’s gears were adjusted based on the terrain encountered, seeking to find out if that realism inspired a greater feeling of immersion. He also provided some test subjects a HUD with their heart rate and other stats, to see if that encouraged gamers to exercise more.

In his current project, [Joey] has equipped a wheelchair with a pair of Arduino-controlled servos that squeeze the brakes to simulate an obstacle. In the VR realm, a player pushes the wheelchair toward a virtual block and the brakes engage, requiring the player push harder to bypass the obstacle.

One imagines the possibilities of games designed for specifically for wheelchairs. The Eyedrivomatic wheelchair that won the 2015 Hackaday Prize sounds perfect for the job!

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