This Force Controlled Robot Gripper Is Less Likely To Break Stuff

March 25, 2019 by No comments

While robotic arms can handle a wide variety of tasks, the specific job at hand will have a major influence on the type of end effector used. For sorting ferromagnetic parts an electromagnet might be enough, while for more accurate location a mechanical gripper could be employed. If you’re working with particularly delicate objects or in concert with human beings, it may be desired to have a force controlled gripper to avoid damage. [James Bruton] has been whipping up a design of his own for just this purpose.

The basic gripper is 3D printed, with 3 fingers consisting of two joints each. Retraction of each finger is courtesy of bungee cord, while extension is via a servo attached to the finger through a spring. The position of each finger is measured with a resistive flex sensor. An Arduino Uno is employed to run the servos and read the attached sensors.

As force is applied by the servo, the spring begins to stretch. This leads to a greater difference between the servo position and the finger position as the applied force increases. By calculating this difference, it’s possible to determine the force applied by the fingers. This can then be used to limit the applied force of the gripper, to avoid breaking delicate objects or crushing soft, fleshy humans.

[James] notes that there are some drawbacks to the current design. The force required to move the fingers is inconsistent along their travel, and this interferes somewhat with accurate measurement. Overall though it’s a solid proof of concept and a good base for further revisions. Files are on Github for those who wish to tinker at home.

Being aware of the forces applied in mechanical settings can be key to getting good results. We’ve even seen arbor presses modified for just such a purpose. Video after the break.

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Hacker Abroad: Cellphone Repair In Huaqiangbei And A Huge Meetup At Seeed

March 25, 2019 by 13 Comments

Shenzhen, China is the home of the legendary electronics markets of Huaqiangbei. Friday was my first full day in the city, having spent the previous three days in Shanghai. We got a little bit of a late start as our flight didn’t arrive until after 1 am and we stayed at the first night at an airport hotel. We met up with Scotty Allen for an amazing meal followed by a very unique experience in the electronics markets, not just seeing the items, but meeting the booth owners who showed off some of their secrets.

The day was capped off by an absolutely packed meetup at X.factory, the collaborative creative space run by Seeed Studio. They lined up a half dozen hardware talks that were quite excellent, and there was a ton of hardware being demonstrated as the night progressed. They had to kick us out or we’d have stayed all night!

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Making The World’s Fastest 555 Timer, Or Using A Modern IC Version

March 25, 2019 by 24 Comments

If you’re not familiar with the 555 timer, suffice it to say that this versatile integrated circuit is probably the most successful ever designed, and has been used in countless designs, many of which fall very far afield from the original intent. From its introduction, the legendary 555 has found favor both with professional designers and hobbyists, and continues to be used in designs from both camps. New versions of the IC are still being cranked out, and discrete versions are built for fun, a temptation I just couldn’t resist after starting this article.

If you think all 555s are the same, think again. Today, a number of manufacturers continue to produce the 555 in the original bipolar formulation as well as lower-power CMOS. While the metal can version is no longer available, the DIP-8 is still around, as are new surface-mount packages all the way down to the chip-scale. Some vendors have also started making simplified variants to reduce the pinout. Finally, you can assemble your own version from a few parts if you need something the commercial offerings won’t do, or just want a fun weekend project. In my case, I came up with what is probably the fastest 555-alike around, although I spared little expense in doing so.

Follow along for a tour of the current state of the 555, and maybe get inspired to design something entirely new with this most versatile of parts.

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ESP32 Video Tricks Hack Chat With Bitluni

March 25, 2019 by 2 Comments

Join us Wednesday at noon Pacific time for the ESP32 Video Tricks Hack Chat!

The projects that bitluni works on have made quite a few appearances on these pages over the last couple of years. Aside from what may or may not have been a street legal electric scooter, most of them have centered around making ESP32s do interesting tricks in the analog world. He’s leveraged the DACs on the chip to create an AM radio transmitter, turned an oscilloscope into a video monitor, and output composite video. That last one was handy for turning a Sony Watchman into a retro game console. He’s also found ways for the ESP32 to output VGA signals. Looks like there’s no end to what he can make the versatile microcontroller do.

Although the conversation could (and probably will) go anywhere, we’ll start with video tricks for the ESP32 and see where it goes from there. Possible topics include:

  • Tricks for pushing the ESP32 DACs to their limits;
  • When to use an external DAC;
  • Optimizing ESP32 code by running on separate cores; and
  • What about HDMI on the ESP32?

You are, of course, encouraged to add your own questions to the discussion. You can do that by leaving a comment on the ESP32 Video Tricks Hack Chat and we’ll put that in the queue for the Hack Chat discussion.

join-hack-chatOur Hack Chats are live community events on the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, March 27, at noon, Pacific time. If time zones have got you down, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.

Building A Turbocharger Turbojet

March 25, 2019 by 17 Comments

Jet engines are known to be highly demanding machines, requiring the utmost attention to tolerances, material specifications, and operating regimes. If any of these parameters are ignored, failures can be catastrophic and expensive. Despite these exacting requirements, it is possible to build a jet engine in the home workshop – and using a turbocharger is a great way to do that. (Video also embedded after the break.)

[Tech Ingredients] does a great job of discussing the basic concepts behind the turbocharger jet engine build, and how various parameters impact performance and efficiency. Through the use of various rules of thumb, developed over years of experimentation by home builders and engineers alike, it’s possible to whip up a functioning engine without too much trial and error. The video breaks down and discusses the thermodynamics at play, as well as practical considerations like cooling and lubrication, in several easy to digest steps.

Jet engines are a popular high-octane build, and we’ve seen it pulled off before by makers like [Colin Furze]. The trick is to pull it off without causing yourself serious injury.

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Could Orion Ride Falcon Heavy To The Moon?

March 25, 2019 by 73 Comments

Things aren’t looking good for NASA’s Space Launch System (SLS). Occasionally referred to as the “Senate Launch System”, or even less graciously, the “Rocket to Nowhere”, the super heavy-lift booster has long been a bone of contention for those in the industry. Designed as an evolution of core Space Shuttle technology, the SLS promised to reuse existing infrastructure to deliver higher payload capacities and lower operating costs than its infamous winged predecessor. But in the face of increased competition from commercial launch providers and proposed budget cuts targeting future upgrades and expansions of the core booster, the significantly over budget and behind schedule program is in a very precarious position.

Which is not to say the SLS doesn’t look impressive, at least on paper. In its initial configuration it would easily take the title as the world’s most powerful rocket, capable of lifting nearly 105 tons into low Earth orbit (LEO), compared to 70 tons for SpaceX’s Falcon Heavy. It would still fall short of the mighty Saturn V’s 155 tons to LEO, but the proposed “Block 2” upgrades would increase SLS payload capability to within striking distance of the iconic Apollo-era booster at 145 tons. Since the retirement of the Space Shuttle in 2011, NASA has been adamant that the might of SLS was the only way the agency could accomplish bigger and more ambitious missions to the Moon, Mars, and beyond.

Or at least, they were. On March 13th, NASA Administrator Jim Bridenstine testified to Congress that in an effort to avoid further delays, the agency is exploring the possibility of sending their Orion spacecraft to the Moon with a commercial launcher. The statement came as a shock to many in the aerospace community, as it would seem to call into question the future of the entire SLS program. If commercial rockets can do the job of SLS, at least in some cases, why does the agency need it?

NASA is currently preparing a report which investigates what physical and logistical modifications would need to be made to missions originally slated to fly on SLS; a document which is sure to be scrutinized by SLS supporters and critics alike. Until the report is released, we can speculate about what this hypothetical flight to the Moon might look like.

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How The Gigatron TTL Microcomputer Works

March 25, 2019 by 26 Comments

About a year ago when Hackaday and Tindie were at Maker Faire UK in Newcastle, we were shown an interesting retrocomputer by a member of York Hackspace. The Gigatron is a fully functional home computer of the type you might have owned in the early 1980s, but its special trick is that it does not contain a microprocessor. Instead of a 6502, Z80, or other integrated CPU it only has simple TTL chips, it doesn’t even contain the 74181 ALU-in-a-chip. You might thus expect it to have a PCB the size of a football pitch studded with countless chips, but it only occupies a modest footprint with 36 TTL chips, a RAM, and a ROM. Its RISC architecture provides the explanation, and its originator [Marcel van Kervinck] was recently good enough to point us to a video explaining its operation.

It was recorded at last year’s Hacker Hotel hacker camp in the Netherlands, and is delivered by the other half of the Gigatron team [Walter Belgers]. In it he provides a fascinating rundown of how a RISC computer works, and whether or not you have any interest in the Gigatron it is still worth a watch just for that. We hear about the design philosophy and the choice of a Harvard architecture, explained the difference between CISC and RISC, and we then settle down for a piece-by-piece disassembly of how the machine works. The format of an instruction is explained, then the detail of their 10-chip ALU.

The display differs from a typical home computer of the 1980s in that it has a full-color VGA output rather than the more usual NTSC or PAL. The hardware is simple enough as a set of 2-bit resistor DACs, but the tricks to leave enough processing time to run programs while also running the display are straight from the era. The sync interval is used to drive another DAC for audio, for example.

The result is one of those what-might-have-been moments, a glimpse into a world in which RISC architectures arrived at the consumer level years earlier than [Sophie Wilson]’s first ARM design for an Acorn Archimedes. There’s no reason that a machine like this one could not have been built in the late 1970s, but as we know the industry took an entirely different turn. It remains then the machine we wish we’d had in the early 1980s, but of course that doesn’t stop any of us having one now. You can buy a Gigatron of your very own, and once you’ve soldered all those through-hole chips you can run the example games or get to grips with some of the barest bare-metal RISC programming we’ve seen. We have to admit, we’re tempted!

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