Hacklet 124 Running Robots And The Claw

September 10, 2016 by Adam Fabio 14 Comments

You never know what you’ll find when you open the projects feed on Hackaday.io. Most weeks, The Hacklet follows a theme of some sort. Sometimes I find projects that just look so cool that I have to get the word out about them.

Such is the case with this week’s first project, Mr. Runner created by [Alex Martin]. Mr. Runner is a quadruped robot that really looks the part. In fact, I’d say it looks like it’s ready to jump off the bench top. Like many of us, [Alex] has been inspired by Boston Dynamics, specifically their Wildcat robot. Wildcat had [Alex] searching the net for walking robot designs. He struck up something he liked with the work of [Dr. Fumiya Iida] and [Dr. Rolf Pfiefer]. In the mid 2000’s, the pair worked out of the University of Zurich. Mr. Runner is based upon their work, with plenty of design tweaks from [Alex].

The basic design is a quadruped with two servos per leg. The servos are at the body and the upper half of the leg. The knee and lower leg are connected by levers and a spring, forming something of a 4 bar linkage. The spring acts as a tendon, absorbing shock, and allowing energy from the servo to be stored and released while the robot runs. [Alex] is experimenting with gaits, controlled by a PC.

Mr. Runner wouldn’t be doing much running without a way to control those 8 servos. [Alex] started with an Arduino and a LynxMotion serial servo controller. This pairing served him well for the first generation of Mr. Runner. For the new version of the robot, he’s rolling his own board based upon Lynxmotion’s
BotBoarduino. The Gerber files have been sent off to OSH Park, and in about a week, Mr. Runner will be off to the races.

Another great recently updated project is Arcade Claw Game Claw Build by [Alex Anderson]. I spent way too many hours of my youth in arcades, and more than a few quarters went into claw games. Sure, they’re usually rigged, but who hasn’t been pulled in by the chance to test your skill and win a prize? A friend asked [Alex] to design an arcade style claw for a game. A seasoned CNC and 3D printing master, [Alex] grabbed his notebook and started sketching. Rack and pinion designs would work well, but didn’t within the constraints of the game. A leadscrew based design would also work, but would be two expensive. Finally, [Alex] settled on a design and fired up his CAD software. He started with two jaw systems to prove out the basic system. Once that was complete, [Alex] moved to a 4 jaw setup.

Much like the arcade games, the claw is actuated by a central plunger. The plunger drives linkages which move the 4 claw jaws. Everything looks good on paper, but when the CAD drawings meet the real world, things get complicated quickly. The initial design relied on a 3D printed part which connected the plunger to the jaw linkages. Any slop in this part would be magnified through the rest of the mechanical system. 3D printers aren’t perfect, and there was some slop — enough that the parts would pinch and bind up while moving.

[Alex] already has a revised design in mind. This is very much a work in progress. That’s the beauty of well documented projects on Hackaday.io — you get to see what works, as well as all the trials and tribulations it took to get to a final working project. Keep at it [Alex], you’re almost there!

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 Hackaday.io!

Careful Crafting Makes DIY 7-Segment Display Shine

September 10, 2016 by Donald Papp 5 Comments

[MattB] decided to go the DIY route for some 7 segment displays that were several inches tall, but he had some particular requirements. He wanted precisely shaped elements that were as cleanly and evenly lit as possible, with no obvious points of illumination from LEDs and no visibly uneven edge lighting. To do this, he used the tools and materials he had on hand and carefully handcrafted each segment. The result is awfully close to his ideal!

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Giant-Scale Physical Pong

September 10, 2016 by Elliot Williams 14 Comments

At first, we thought we were having deja vu, but then we saw this video embedded below. [Thijs Eerens] is a creative technologist (dare we say, a “hacker”?) who builds giant-scale games for a living. For the Lowlands festival in the Netherlands, he contributed to the build of a huge Pong game that looks as big as a cinema screen.

The paddles appear to be controlled by pulling ropes, and the “ball” is driven around on a system of wires and stepper motors. Code running in the background tracks the player paddles, drives the ball, and keeps score. From the video, there seem to be sound effects involved. It looks like a lot of fun.

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Bring Doping, Microfluidics, Photovoltaics, And More Into The Home

September 10, 2016 by Gerrit Coetzee 15 Comments

Can you make a spectrometer for your home lab all from materials you have sitting around? We might not believe it from a less credible source, but this MIT course does indeed build a spectrometer from foam board using two razor blades as the silt cover and a writable CD as the diffraction grating. The coolest part is removing the metal backing of the CD.

Hackaday reader [gratian] tipped us off about the course available from MIT courseware called Nanomaker. It boils down some fairly complicated experiments to the kind one can do in the home lab without involving thousands of dollars of lab equipment. The whole point is to demystify what we think of as complicated devices and topics surrounding photovoltaics, organic photovoltaics, piezoelectricity and thermoelectricity.

Spectrometers are used to analyze the wavelengths of a light source. Now that you have a measurement tool in hand it’s time to build and experiment with some light sources of your own. Here you can see an LED that is the topic of one of the course labs.

If you have a bit of background in chemistry this is a good step-by-step guide for getting into these types of experiments at home. It reminds us of some of the really cool stuff [Jeri Ellsworth] was doing in her garage lab, like making her own EL panels.

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Hackaday Prize Entry: Characterizing LED And Laser Diodes

September 9, 2016 by Brian Benchoff 15 Comments

Needless to say, we’re fascinated by LEDs, laser diodes, and other blinkies. Although we can get just about any light emitting thing, the data sheets aren’t always accurate or available. For his Hackaday Prize entry, [Ted] is building a device to characterize the efficiency, I/V curve, and optical properties of all the blinkies. It’s a project to make glowy stuff better, and a great entry for the Hackaday Prize.

The inspiration for this project came from two of [Ted]’s projects, one requiring response curves for LEDs, and laser diodes for another. This would give him a graph of optical output vs. current, angular light output distribution, and the lasing threshold for laser diodes. This data isn’t always available in the datasheet, so a homebrew tool is the only option.

The high-level design of this tool is basically a voltmeter and ammeter measuring a glowy diode, producing IV curves and measuring optical output. That takes care of all the measurements except for the purely optical properties of a LED. This is measured by a goniometer, or basically putting the device under test on a carriage attached to a stepper motor and moving it past a fixed optical detector.

If you’re wondering why this device is needed and a simple datasheet is insufficient, check this out. [Ted] measured the efficiency of a Luxeon Z LED, and found the maximum efficiency is right around 10mA. The datasheet for this LED shows a nominal forward current of 500mA, and a maximum of 1000mA. If you just looked at the datasheet, you could easily assume a device powered for years by a coin cell would be impossible. It’s not, and [Ted]’s device gave us this information.

Landscape Lighting That Also Texts

September 9, 2016 by Bryan Cockfield 5 Comments

Your local hardware store or garden supply center probably has everything you need to install landscape lighting all around your property. What’s a little less likely is coming out of that situation with fewer holes in your wallet than in your yard. And even then, it’s pretty much guaranteed that any off-the-shelf equipment won’t send you a text message when your landscape lighting isn’t working properly. [Mark]’s landscape lighting system does, though!

Powered by a Raspberry Pi, this landscape lighting system has every feature imaginable. It can turn the lighting on at sunset and turn it off at a set or random time later in the evening. There’s a web interface served from the Pi that allows further user control. The Raspberry Pi also monitors the lighting and can sense when one of the lights burns out. When one does, the Pi uses Twillo to send a text message notification.

There’s not many more features we can imagine packing into a setup like this. Of course, if you don’t have a spare Pi around you can probably manage to get the job done with an ESP8266, or even an old-fashioned Arduino.

VW Engineer Pleads Guilty To Conspiracy

September 9, 2016 by Mike Szczys 173 Comments

[James Liang], an engineer at Volkswagen for 33 years, plead guilty today to conspiracy. He was an engineer involved in delivering Diesel vehicles to market which could detect an emissions test scenario and perform differently from normal operation in order to pass US emission standards.

A year ago we talked about the Ethics in Engineering surrounding this issue. At the time we wondered why any engineer would go along with a plan to defraud customers. We may get an answer to this after all. [Mr. Liang] will cooperate with authorities as the VW probe continues.

According to information in the indictment, none of this happened by mistake (as we suspected). There was a team responsible for developing a mode that would detect a test and pass inspection after the company discovered the engine could not otherwise pass. It’s not hard to see the motivation behind this — think of the sunk cost in developing an engine design. The team responsible for cheating the tests went so far as to push software updates in 2014 which made the cheat better, and lying about the existence of these software “features” when questioned by authorities (again, according to the indictment).