Flexures Keep This Printed Displacement Sensor In Line

May 18, 2024 by 1 Comment

When the job at hand is measuring something with micron-range precision, thoughts generally turn to a tool with a Mitutoyo or Starrett nameplate. But with a clever design and a little electronics know-how, it turns out you can 3D print a displacement sensor for measuring in the micron range for only about $10.

While the tool that [BubsBuilds] came up with isn’t as compact as a dial indicator and probably won’t win any industrial design awards, that doesn’t detract from its usefulness. And unlike a dial indicator — at least the analog type — this sensor outputs an easily digitized signal. That comes courtesy of a simple opto-interrupter sensor, which measures the position of a fine blade within its field of view. The blade is attached to a flexure that constrains its movement to a single plane; the other end of the flexure has a steel ball acting as a stylus. In use, any displacement of the stylus results in more or less light being received by the phototransistor in the opto-interrupter; the greater the deflection, the less light and the lower the current through the transistor. In addition to the sensor itself, [Bub] printed a calibration jig that allows precision gauge blocks or simple feeler gauges to be inserted in front of the stylus. The voltage across the emitter resistor for these known displacements is then used to create a calibration curve.

[Bub] says he’s getting 5-micron repeatability with careful calibration and multiple measurements of each gauge block, which seems pretty impressive to us. If you don’t need the digital output, this compliant mechanism dial indicator might be helpful too. Continue reading “Flexures Keep This Printed Displacement Sensor In Line” →

NetBSD Bans AI-Generated Code From Commits

May 18, 2024 by 12 Comments

A recent change was announced to the NetBSD commit guidelines which amends these to state that code which was generated by Large Language Models (LLMs) or similar technologies, such as ChatGPT, Microsoft’s Copilot or Meta’s Code Llama is presumed to be tainted code. This amendment was to the existing section about tainted code, which originally referred to any code that was not written directly by the person committing the code, and was due to licensing concerns. The obvious reason behind this is that otherwise code may be copied into the NetBSD codebase which may have been licensed under an incompatible (or proprietary) license.

In the case of LLM-based code generators like the above-mentioned, the problem stems from the fact that they are trained on millions of lines of code from all over the internet, which are naturally released under a wide variety of licenses. Invariably, some of that code will be covered by a license that’s not acceptable for the NetBSD codebase. Although the guideline mentions that these auto-generated code commits may still be admissible, they require written permission from core developers, and presumably an in-depth audit of the code’s heritage. This should leave non-trivial commits that got churned out by ChatGPT and kin out in the cold.

The debate about the validity of works produced by current-gen “artificial intelligence” software is only just beginning, but there’s little question that NetBSD has made the right call here. From a legal and software engineering perspective this policy makes perfect sense, as LLM-generated code simply doesn’t meet the project’s standards. That said, code produced by humans brings with it a whole different set of potential problems.

Put A Little Pigeon In Your Next Clock Project

May 17, 2024 by 6 Comments

If you’re anything like us, you’ve probably wondered why gear teeth are shaped the way they’re shaped. But we’ll go out on a limb and say you’ve never wondered why gear teeth aren’t shaped like pigeons, and what a clock that’s not quite a clock based around them would look like.

If this sounds like it has [Uri Tuchman] written all over it, give yourself a cookie. [Uri] has a thing for pigeons, and they make an appearance in nearly all his whimsical builds, from his ink-dipping machine to his intricately engraved metal mouse. For this build, pigeons are transformed into the teeth of a large, ornate wheel, cut from brass using an impressive Friedrich Deckel pantograph engraver. To put the pigeon wheel to work, [Uri] built an escapement and a somewhat crooked pendulum, plus a drive weight and dial. It’s almost a clock, but not quite, since it doesn’t measure time in any familiar units, and the dial has a leg rather than hands — classic [Uri].

It may not be [Clickspring]-level stuff, but it’s still a lovely piece of work, and instructive to boot. The way [Uri] figured out the profile for the meshing teeth by looking at the negative space swept out by the pigeon profiles was pretty sweet. Plus, pigeons.

Continue reading “Put A Little Pigeon In Your Next Clock Project” →

Winamp Source Code Will Be Opened Up, Company Says

May 17, 2024 by 21 Comments

Recently the company currently in charge of the Winamp media player – formerly Radionomy, now Llama Group – announced that it will be making the source code of the player ‘available to developers’. Although the peanut gallery immediately seemed to have jumped to the conclusion that this meant that the source would be made available to all on the announced 24 September 2024 date, reading between the lines of the press release gives a different impression.

First there is the sign-up form for ‘FreeLlama’ where interested developers can sign up, with a strong suggestion that only vetted developers will be able to look at the code, which may or may not be accompanied by any non-disclosure agreements. It would seem appropriate to be skeptical considering Winamp’s rocky history since AOL divested of it in 2013 with version 5.666 and its new owner Radionomy not doing much development on the software except for adding NFT and crypto/blockchain features in 2022. The subsequent Winamp online service doubled down on this.

Naturally it would be great to see Winamp become a flourishing OSS project for the two dozen of us who still use Winamp on a daily base, but the proof will be in the non-NFT pudding, as the saying goes.

Improved 3D Scanning Rig Adds Full-Sized Camera Support

May 17, 2024 by 2 Comments

There are plenty of reasons to pick up or build a 3D scanner. Modeling for animation or special effects, reverse engineering or designing various devices or products, and working with fabrics and clothing are all well within the wide range of uses for these tools. [Vojislav] built one a few years ago which used an array of cameras to capture 3D information but the Pi camera modules used in this build limited the capabilities of the scanner in some ways. [Vojislav]’s latest 3D scanner takes a completely different approach by using a single high-quality camera instead.

The new 3D scanner is built to carry a full-size DSLR camera, its lens, and a light. Much more similarly to how a 3D printer works, the platform moves the camera around the object in programmable steps for the desired 3D scan. The object being scanned sits on a rotating plate as well, allowing for the entire object to be scanned without needing to move the camera through a full 180° in two axes. The scanner can also be used for scanning more 2D objects while capturing information about texture, such as various textiles.

For anyone looking to reproduce something like this, [Vojislav] has made all of the plans for this build available on the project’s GitHub page including some sample gcode to demonstrate the intended use for the scanner. On the other hand, if you’re short the often large amount of funding required to get a DSLR camera, his older 3D scanner is still worth taking a look at as well.

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Emulating Biology For Robots With Rolling Contact Joints

May 17, 2024 by 2 Comments

Joints are an essential part in robotics, especially those that try to emulate the motion of (human) animals. Unlike the average automaton, animals are not outfitted with bearings and similar types of joints, but rather rely sometimes on ball joints and a lot on rolling contact joints (RCJs). These RCJs have the advantage of being part of the skeletal structure, making them ideal for compact and small joints. This is the conclusion that [Breaking Taps] came to as well while designing the legs for a bird-like automaton.

These RCJs do not just have the surfaces which contact each other while rotating, but also provide the constraints for how far a particular joint is allowed to move, both in the forward and backward directions as well as sideways. In the case of the biological version these contact surfaces are also coated with a constantly renewing surface to prevent direct bone-on-bone contact. The use of RCJs is rather common in robotics, with the humanoid DRACO 3 platform as detailed in a 2023 research article by [Seung Hyeon Bang] and colleagues in Frontiers in Robotics and AI.

The other aspect of RCJs is that they have to be restrained with a compliant mechanism. In the video [Breaking Taps] uses fishing line for this, but many more options are available. The ‘best option’ also depends on the usage and forces which the specific joint will be subjected to. For further reading on the kinematics in robotics and kin, we covered the book Exact Constraint: Machine Design Using Kinematic Principles by [Douglass L. Blanding] a while ago.

Continue reading “Emulating Biology For Robots With Rolling Contact Joints” →

Raspberry Pi Files Paperwork With The London Stock Exchange

May 17, 2024 by 20 Comments

If you’re a regular visitor to the Raspberry Pi website and you have a sharp eye, you may have noticed during the last few days a new link has appeared in their footer. Labelled “Investor relations“, it holds links to the documents filed with the London Stock Exchange of their intention to float. In other words, it’s confirmation of their upcoming share offering.

It has been interesting to watch the growth of Raspberry Pi over the last twelve years, from cottage industry producing a thousand boards in China, to dominating the SBC market and launching their own successful silicon. Without either a crystal ball or a window into Eben Upton’s mind, we’re as unreliable as anyone else when it comes to divining their future path. But since we’re guessing that it will involve ever more complex silicon with a raspberry logo, it’s obvious that the float will give them the investment springboard they need.

For those of us who have been around for a long time this isn’t the first company in our corner of the technology world we’ve seen burn brightly. It’s not even the first from Cambridge. Appointing ourselves as pundits though, we’d say that Raspberry Pi’s path to this point has been surprisingly understated, based upon the strength of its products rather than hype, and while Eben is undoubtedly a well-known figure, not based upon a cult of personality. There is already a significant ecosystem around Raspberry Pi, we’d like to think that this move will only strengthen it. We may not be looking at the British Microsoft, but we don’t think we’re looking at another Sinclair either.