People learn in different ways, but sometimes the establishment fixates on explaining a concept in one way. If that’s not your way you might be out of luck. If you have trouble internalizing floating point number representations, the Internet is your friend. [Fabian Sanglard] (author of Game Engine Black Book: Wolfenstein 3D) didn’t like the traditional presentation of floating point numbers, so he decided to explain them a different way.
Here on Hackaday, too often do we turn our heads and gaze at the novelty of 3D printing functional devices. It’s easy to forget that other techniques for assembling functional prototypes exist. Here, [Reuben] nails the aspect of functional prototyping with the laser cutter with a real-world application: a roll-pitch friction differential drive built from just off-the shelf and laser-cut parts!
The centerpiece is held together with friction, where both the order of assembly and the slight wedged edge made from the laser cutter kerf keeps the components from falling apart. Pulleys transfer motion from the would-be motor mounts, where the belts are actually tensioned with a roller bearing mechanism that’s pushed into position. Finally, the friction drive itself is made from roller-blade wheels, where the torque transferred to the plate is driven by just how tightly the top screw is tightened onto the wheels. We’d say that [Reuben] is pushing boundaries with this build–but that’s not true. Rather, he’s using a series of repeatable motifs together to assemble a both beautiful and complex working mechanism.
This design is an old-school wonder from 2012 uncovered from a former Stanford course. The legendary CS235 aimed to teach “unmechanically-minded” roboticists how to build a host of mechanisms in the same spirit as MIT’s How-to-make-almost-Anything class. While CS235 doesn’t exist anymore, don’t fret. [Reuben] kindly posted his best lectures online for the world to enjoy.
Continue reading “Friction Differential Drive Is A Laser-Cut Triumph”
Here at Hackaday, we write for a community of readers who are inquisitive about the technology surrounding them. You wouldn’t be here if you had never taken a screwdriver to a piece of equipment to see what makes it work. We know that as well as delving inside and modifying devices being core to the hardware hacker mindset, so is repairing. If something we own breaks, we try to work out why it broke, and what we can do to fix it.
Unfortunately, we live in an age in which fixing the things we own is becoming ever harder. Manufacturers either want to sell us now hardware rather than see us repair what breaks, or wish to exercise total control over the maintenance of their products. They make them physically impossible to repair, for example by gluing together a cellphone, or they lock down easy-to-repair items with restrictive software, for example tractors upon which every replacement part must be logged on a central computer.
This has been a huge issue in our community for a long time now, but to the Man In The Street it barely matters. To the people who matter, those who could change or influence the situation, it’s not even on the radar. Which makes a piece in the British high-end weekly newspaper The Economist particularly interesting. Entitled “A ‘right to repair’ movement tools up“, it lays out the issues and introduces the Repair Association, a political lobby group that campaigns for “Right to repair” laws in the individual states of the USA.
You might now be asking why this is important, why are we telling you something you already know? The answer lies in the publication in which it appears. The Economist is aimed at politicians and influencers worldwide. In other words, when we here at Hackaday talk about the right to repair, we’re preaching to the choir. When they do it at the Economist, they’re preaching to the crowd who can make a difference. And that’s important.
You may recognise the tractors mentioned earlier as the iconic green-and-yellow John Deere. We’ve written about their DRM before.
Neon sign, All Electronics Service, Portland, Visitor7 [CC BY-SA 3.0].
For those who have suffered a stroke, recovery is a long and slow process that requires rehabilitation to start as early as possible. Quite often, secondary stroke attacks complicate matters. Spasticity — muscle contraction and paresis — muscular weakness, are two of the many common after-effects of stroke. Recovery involves doing repeated exercises to strengthen the muscles and bring back muscle memory. Benchmarking progress becomes difficult when caregivers are only able to use qualitative means such as squeezing tennis balls to monitor improvement. To help provide quantitative measurements in such cases, [Sergei V. Bogdanov] is building a Dynamometer for Post-Stroke Rehabilitation. It is an Open Source, 4-channel differential force gauge for measuring and logging the progress of the patient. The device measures, graphs, and logs the force exerted by the four fingers when they push down on the four force gauges.
The device consists of four strain gauges obtained from cheap kitchen scales. The analog outputs from these are fed to HX-711 24-bit ADC boards. An Arduino Nano processes the data and displays it on two banks of eight-digit LED modules. [Sergei] also experimented with a 20×4 character LCD in place of the LED display. In the standalone mode, the device can only indicate the measured forces on the LED (or LCD) display which is calibrated to display either numerical values or a logarithmic scale. When connected to a serial port and using the (Windows only) program, it is possible to not only view the same information but also save it at regular, set intervals. The data can also be viewed in graphical form.
The project page provides links to their Arduino code, Windows monitor program as well as build instructions. Check out the related assistive technology project that [Sergei] is working on — A Post Stroke Spasticity Rehab Helper.
Continue reading “Hackaday Prize Entry: Dynamometer For Post Stroke Rehabilitation”
It isn’t really a book, but Richard Feynman’s Appendix to the Challenger Disaster Report is still definitely something you should read. It’s not particularly long, but it’s educational and relevant not just as an example of critical thinking in action, but as a reminder not to fool oneself; neither individually, nor on an organizational level. Sadly, while much was learned from the events leading to and surrounding the Challenger disaster, over thirty years later many of us can still find a lot of the same things to relate to in our own professional lives. There isn’t a single magic solution, because these problems are subtle and often masquerade as normal.
Richard Feynman (1918-1988) was a Nobel Prize winning physicist and one of the best-known scientists of his time. In 1986 he somewhat reluctantly agreed to join the Rogers Commission, whose task was to investigate the Challenger disaster. The space shuttle Challenger had exploded a little more than a minute after launch, killing everyone on board. The commission’s job was to find out what had gone wrong and how it had happened, and figure out how to keep it from happening again.
Continue reading “Books You Should Read: Feynman’s Appendix To The Challenger Disaster Report”
Have you ever stood under a dome and whispered, only to hear the echo of your voice come back much louder? Researchers at NIST used a similar principle to improve the atomic force microscope (AFM), allowing them to measure rapid changes in microscopic material more accurately than ever before.
An AFM works by using a minuscule sharp probe. The instrument detects deflections in the probe, often using a piezoelectric transducer or a laser sensor. By moving the probe against a surface and measuring the transducer’s output, the microscope can form a profile of the surface. The NIST team used a laser traveling through a circular waveguide tuned to a specific frequency. The waveguide is extremely close (150 nm) to a very tiny probe weighing about a trillionth of a gram. When the probe moves a very little bit, it causes the waveguide’s characteristics to change to a much larger degree and a photodetector monitoring the laser light passing through the resonator can pick this up.
Continue reading “NIST Uses Optical Resonance To Probe Atoms”
Build something cool and pick up new skills from the workshops at the Hackaday Superconference. Last week we announced all of the talks you’ll find at Supercon, and starting today you can reserve your spot at one of the workshops.
You must have a Superconference ticket in order to purchase a workshop ticket; buy one right now if you haven’t already. You can get mechanical with Haptics and Animatronics, take your product design from schematic to PCB and enclosure, brush up your embedded development on several choices of platform, make cell towers do your bidding, or dump way too many volts into a block of wood.
Space in these workshops is limited so make sure to sign up before all the seats are taken. The base price for workshops is $10 (basically a “skin in the game” price to encourage those who register to show up). Any tickets priced above that base is meant to cover the material expense of the workshop. Here’s what we have planned:
Superconference workshops tend to sell out extremely quickly. Don’t wait to get your ticket.
