The Difference Between 4WD And AWD

March 31, 2021 by Lewin Day 102 Comments

Car manufacturers will often tout a vehicle’s features to appeal to the market, and this often leads to advertisements featuring a cacophony of acronyms and buzzwords to dazzle and confuse the prospective buyer. This can be particularly obvious when looking at drivelines. The terms four-wheel drive, all-wheel drive, and full-time and part-time are bandied about, but what do they actually mean? Are they all the same, meaning all wheels are driven or is there more to it? Let’s dive into the technology and find out.

Part-Time 4WD

Part-time four-wheel drive is the simplest system, most commonly found on older off-road vehicles like Jeeps, Land Cruisers and Land Rovers up to the early 1990s, as well as pickup trucks and other heavy duty applications. In these vehicles, the engine sends its power to a transfer case, which sends an equal amount of torque to the front and rear differentials, and essentially ties their input shafts together. This is good for slippery off-road situations, as some torque is provided to both axles at all times. However, this system has the drawback that it can’t be driven in four-wheel drive mode at all times. With the front and rear differentials rotating together, any difference in rotational speed between the front and rear wheels — such as from turning a corner or uneven tyre wear — would cause a problem. The drive shaft going to one differential would want to turn further than the other, a problem known as wind-up.

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Web Tool Cranks Up The Power On DJI’s FPV Drone

March 31, 2021 by Tom Nardi 22 Comments

Apparently, if the GPS on your shiny new DJI FPV Drone detects that it’s not in the United States, it will turn down its transmitter power so as not to run afoul of the more restrictive radio limits elsewhere around the globe. So while all the countries that have put boots on the Moon get to enjoy the full 1,412 mW of power the hardware is capable of, the drone’s software limits everyone else to a paltry 25 mW. As you can imagine, that leads to a considerable performance penalty in terms of range.

But not anymore. A web-based tool called B3YOND promises to reinstate the full power of your DJI FPV Drone no matter where you live by tricking it into believing it’s in the USA. Developed by the team at [D3VL], the unlocking tool uses the new Web Serial API to send the appropriate “FCC Mode” command to the drone’s FPV goggles over USB. Everything is automated, so this hack is available to anyone who’s running a recent version of Chrome or Edge and can click a button a few times.

There’s no source code available yet, though the page does mention they will be putting up a GitHub repository soon. In the meantime, [D3VL] have documented the command packet that needs to be sent to the drone over its MODBUS-like serial protocol for others who might want to roll their own solution. There’s currently an offline Windows-only tool up for download as well, and it sounds like stand-alone versions for Mac and Android are also in the works.

It should probably go without saying that if you need to use this tool, you’ll potentially be violating some laws. In many European countries, 25 mW is the maximum unlicensed transmitter power allowed for UAVs, so that’s certainly something to keep in mind before you flip the switch. Hackaday isn’t in the business of dispensing legal advice, but that said, we wouldn’t want to be caught transmitting at nearly 60 times the legal limit.

Even if you’re not interested in fiddling with drone radios, it’s interesting to see another practical application of the Web Serial API. From impromptu oscilloscopes to communicating with development boards and conference badges, clever developers are already finding ways to make hardware hacking easier with this new capability.

[Thanks to Jules for the tip.]

Boston Dynamics Stretch Robot Trades Lab Coat For Work Uniform

March 31, 2021 by Roger Cheng 30 Comments

Boston Dynamics has always built robots with agility few others could match. While great for attention-getting demos, from outside the company it hasn’t been clear how they’ll translate acrobatic skills into revenue. Now we’re getting a peek at a plan in an interview with IEEE Spectrum about their new robot Stretch.

Most Boston Dynamics robots have been research projects, too expensive and not designed for mass production. The closest we got to date was Spot, which was offered for sale and picked up a few high profile jobs like inspecting SpaceX test sites. But Spot was still pretty experimental without an explicit application. In contrast, Stretch has a laser-sharp focus made clear by its official product page: this robot will be looking for warehouse jobs. Specifically, Stretch is designed to handle boxes up to 50 lbs (23 kg). Loading and unloading them, to and from pallets, conveyer belts, trucks, or shipping containers. These jobs are repetitive and tedious back-breaking work with a high injury rate, a perfect opportunity for robots.

But warehouse logistics aren’t as tightly structured as factory automation, demanding more adaptability than typical industrial robots can offer. A niche Boston Dynamics learned it can fill after releasing an earlier demo video showing their research robot Atlas moving some boxes around: they started receiving inquiries into how much that would cost. Atlas is not a product, but wheels were set in motion leading to their Handle robot. Learning from what Handle did well (and not well) in a warehouse environment, the designed evolved to today’s Stretch. The ostrich-like Handle prototype is now relegated to further research into wheeled-legged robots and the occasional fun dance video.

The Stretch preproduction prototypes visible in these videos lacks acrobatic flair of its predecessors, but they still have the perception and planning smarts that made those robots possible. Those skills are just being applied to a narrower problem scope. Once production models are on the job, we look forward to reading some work performance reviews.

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Sawblade Turned Beyblade Looks Painful To Tangle With

March 30, 2021 by Lewin Day 14 Comments

Beyblades were a huge craze quite some years back. Children battled with spinning tops in small plastic arenas, or, if their local toy stores were poorly merchandised, in salad bowls and old pie dishes. The toys were safe enough, despite their destructive ethos, by virtue of being relatively small and lightweight. This “Beyblade” from [i did a thing] is anything but, however.

The build begins with a circular saw blade over 1 foot in diameter, replete with many angry cutting teeth that alone portend danger for any individual unlucky enough to cross its path. Saw blades tend to cut slowly and surely however, so to allow the illicit Bey to deal more traumatic blows, a pair of steel scraps are welded on to deliver striking blows as well. This has the added benefit of adding more mass to the outside of the ‘blade, increasing the energy stored as it spins.

With the terrifying contraption spun up to great RPM by a chainsaw reeling in string, it’s able to demolish cheap wood and bone with little resistance. Shrapnel is thrown in many directions as the spinner attacks various objects, from a melon to an old CRT TV. We’d love to see the concept taken further, with an even deadlier design spun up to even higher speeds, ideally with a different tip that creates a more aggressive motion across the floor.

As aggressive as this saw blade looks in action, not all are so scary. Even paper can do the job under the right conditions. Video after the break.

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Wires Vs Words — PCB Routing In Python

March 30, 2021 by Chris Lott 30 Comments

Preferring to spend hours typing code instead of graphically pushing traces around in a PCB layout tool, [James Bowman] over at ExCamera Labs has developed CuFlow, a method for routing PCBs in Python. Whether or not you’re on-board with the concept, you have to admit the results look pretty good.

Key to this project is a concept [James] calls rivers — the Dazzler board shown above contains only eight of them. Connections get to their destination by taking one or more of these rivers which can be split, joined, and merged along the way as needed in a very Pythonic manner. River navigation is performed using Turtle graphics-like commands such as left(90) and the appropriately named shimmy(d)that aligns two displaced rivers. He also makes extensive use of pin / gate swapping to make the routing smoother, and there’s a nifty shuffler feature which arbitrarily reorders signals in a crossbar manner. Routing to complex packages, like the BGA shown, is made easier by embedding signal escapes for each part’s library definition.

We completely agree with [James]’s frustration with so many schematics these days being nothing more than a visual net lists, not representing the logical flow and function of the design at all. However, CuFlow further obfuscates the interconnections by burying them deep inside the wire connection details. Perhaps, if CuFlow were melded with something like the SKiDL Python schematic description language, the concept would gain more traction?

That said, we like the concept and routing methodologies he has implemented in CuFlow. Check it out yourself by visiting the GitHub repository, where he writes in more detail about his motivation and various techniques. You may remember [James] two of his embedded systems development tools that we covered back in 2018 — the SPI Driver and the I2C driver.

Custom Built 12-Port A/V Switch Keeps CRT Well Fed

March 30, 2021 by Tom Nardi 5 Comments

Classic gaming aficionados who prefer to play on real hardware know the struggle of getting their decades-old consoles connected to a modern TV. Which is why many gamers chose to keep a contemporary CRT TV around for when they want to take a walk down memory lane. Unfortunately those old TVs usually didn’t offer more than a few A/V ports on the back, so you’ll probably need to invest in a A/V switch to keep them all hooked up at once.

That’s the situation [Thomas Sowell] found himself in, except he couldn’t find one with enough ports. Rather than chain switches together, he decided to build his own custom 12-port console selector. With an integrated amplifier to keep everything looking sharp, a handsome walnut and metal enclosure, and a slick graphical interface that shows the logo of the currently selected console on a Vacuum Fluorescent Display (VFD), the final product is a classic gamer’s dream come true.

To switch the audio [Thomas] is using a pair of ADG1606 16-channel analog multiplexers, while video is shuffled around with four MAX4315 8-channel video multiplexer-amplifiers. The math might seem a bit off at first, but he’s using one ADG1606 for each stereo channel and since the switch is for S-Video, each device has a luminance and color signal that needs to be handled separately. The multiplexers are flipped with a ATmega2561 microcontroller, which is also responsible for reading user input from a rotary encoder on the front of the case and displaying the appropriate console logo on the 140×32 Noritake VFD.

You may be surprised to find that [Thomas] considered himself an electronics beginner when he started this project, and that this is only the second PCB he’s ever designed. Was this a bold second project? Sure. But it also speaks to how far DIY electronics has come over the last years. Powerful open source tools, modular components, and of course a community of creative folks willing to share their knowledge and designs, has gone a long way towards redefining whats possible for the individual hacker and maker.

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Pneumatic Actuator Made Out Of Lasercut Plastic

March 30, 2021 by Lewin Day 17 Comments

Pneumatics are a great solution for all kinds of actuators, and can even be used for logic operations if you’re so inclined. Typically, such actuators rely on nicely machined metal components with airtight rubber seals. But what if you did away with all that? [Richard Sewell] decided to investigate.

The result is a pneumatic actuator built out of lasercut acetal parts. The mechanism consists of of two outer layers of plastic acting as the enclosure, and a cut-out middle layer which creates the air chamber and houses the actuating arm itself. It’s a single-acting design, meaning the air can push the actuator one way, with a spring for return to the neutral position. The action is quite fast and snappy, too.

[Richard] aims to tweak the design further by improving the registration between the features of each layer and reduce the rubbing of the actuator’s rotor on the surrounding parts. If you’ve got the know-how, sound off in the comments. Alternatively, consider looking into soft pneumatics as well. Video after the break.

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