Building And Flying A Helicopter With A Virtual Swashplate

June 25, 2020 by Dan Maloney 33 Comments

They say that drummers make the best helicopter pilots, because to master the controls of rotary-wing aircraft, you really need to be able to do something different with each limb and still have all the motions coordinate with each other. The control complexity is due to the mechanical complexity of the swashplate, which translates control inputs into both collective and cyclical changes in the angle of attack of the rotor blades.

As [Tom Stanton] points out in his latest video, a swashplate isn’t always needed. Multicopters dispense with the need for one by differentially controlling four or more motors to provide roll, pitch, and yaw control. But thanks to a doctoral thesis he found, it’s also possible to control a traditional single-rotor helicopter by substituting flexible rotor hinges and precise motor speed control for the swashplate.

You only need to watch the slow-motion videos to see what’s happening: as the motor speed is varied within a single revolution, the tips of the hinged rotor blades lead and lag the main shaft in controlled sections of the cycle. The hinge is angled, which means the angle of attack of each rotor blade changes during each rotation — exactly what the swashplate normally accomplishes. As you can imagine, modulating the speed of a motor within a single revolution when it’s spinning at 3,000 RPM is no mean feat, and [Tom] goes into some detail on that in a follow-up video on his second channel.

It may not replace quadcopters anytime soon, but we really enjoyed the lesson in rotor-wing flight. [Tom] always does a great job of explaining things, whether it’s the Coandă effect or anti-lock brakes for a bike.

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Building A Scooter Exhaust From Scrap Metal

June 23, 2020 by Lewin Day 20 Comments

When a part on a vehicle fails, oftentimes the response is to fit a new one fresh out the box. However, sometimes, whether by necessity or simply for the love of it, it’s possible to handcraft a solution instead. [Samodel] does just that when whipping up a new exhaust for his scooter out of scrap metal.

It’s a great example of classic backyard metalworking techniques. The flange is recreated using a cardboard template rubbed on the exhaust port, with the residual oil leaving a clear impression. Hard work with a grinder and drill get things started, with an insane amount of filing to finish the piece off nicely. A properly tuned pipe is then sketched out on the computer, and a paper template created. These templates are cut out of an old fridge to create the main muffler section.

There’s plenty of other hacks, too – from quick and dirty pipe bends to handy sheet forming techniques. It’s not the first time we’ve seen great metalworking with scrap material, either. Video after the break.

[Thanks to BrendaEM for the tip]

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Voice-Command Chess Board Powered By Alexa

June 22, 2020 by Lewin Day 6 Comments

Talking to computers used to be reserved for Star Trek and those with overactive imaginations. Now, it’s a regular part of daily life. [CodersCafe] decided to put this technology to work in a chess robot, with the help of Amazon’s digital assistant.

The build relies on an Cartesian motion rig, built out of Lego Technics parts. The end effector is fitted with a magnet , fitted onto the Z-axis screw for engaging and disengaging with the pieces. A Mindstorms EV3 controller is used to run the show, hooked up over Bluetooth to an Amazon Echo. This allows the user to ask Alexa to move the pieces for the white player in natural language – by saying, for example, “move from B1 to C3”.

It’s a build that demonstrates how easy it is to create projects with advanced functionality by lacing together the correct off-the-shelf hardware. Other Cartesian-type motion platforms can make great chess robots, too. Video after the break.

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VGA Framegrabber Built From Scratch

June 21, 2020 by Lewin Day 35 Comments

Modern computers are replete with all manner of digital video interfaces. DVI, HDMI, DisplayPort are all examples of this. In the old days, VGA ruled the roost, sending video to monitors as an analog signal. However, it’s possible to convert this back into a digital format, and [vihapuu] has done just that with his Grabor project. (a demo video is also embedded below.)

The project relies on a Texas Instruments TVP7002 to do the hard work of converting VGA into a digital signal. The output of this chip is then picked up by a CPLD which clocks the resulting data into SRAM. An NXP microcontroller is then responsible for taking the data from SRAM and sending it out over a network interface, thanks to a Microchip ENC28J60 Ethernet controller.

We can imagine this kind of tool would come in handy for working with retro machines over a network. We’ve seen other interesting VGA hacks before too, like this EEPROM-based signal generator. Video after the break.

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Plant’m If You Got’m And Keep’m Alive

June 19, 2020 by Kristina Panos 13 Comments

Having a few plants around is a great way to liven up your living and/or working space. They look nice, you get to watch them grow and change, and some types of plants can actively improve the room’s air quality. But let’s face it — even the easy ones require a baseline level of care that can easily fall by the wayside. After all, the poor things can’t scream out for water or get up and find a sunnier spot for themselves.

[Ine Hocedez] was tired of watching her plants die and not knowing why. The two main culprits involve water and light, though there can be other issues like soil pH and bugs. It’s easy to get the balance wrong, so why not automate everything?

Plant’m is a complete, portable package that [Ine] designed for a school project. A soil moisture sensor dictates the watering schedule via Raspberry Pi, and water is automatically pumped from an elevated tank.

The lamp is meant to supplement the sunlight, not replace it. But that’s the real beauty of this botanical box — [Ine] can just pick it up and try a different spot if the plant droops or shows burnt spots.

Got the sunlight part down for your plant, but can’t remember to water it? Re-purpose an old Keurig and give it an automatic drip.

Notification Wearable Helps Get Child’s Attention

June 14, 2020 by Lewin Day 9 Comments

Getting a child’s attention can be difficult at the best of times. Add deafness into the picture, and it’s harder again. [Jake]’s daughter recently had to go without her cochlear implants, raising this issue. Naturally, he whipped up some hardware to solve the problem.

[Jake]’s solution was to devise a vibrating wristband that could be used to get his daughter’s attention. An Adafruit Trinket M0 is used to vibrate a pager motor, using a DRV2605 motor driver. This is paired with a Tile Bluetooth device, allowing the unit to interface with Google Assistant. This allows [Jake] to get his daughter’s attention with a simple voice command to a smartphone, tablet or smart speaker.

While [Jake]’s daughter will regain her cochlear implants soon, they do have limitations as far as hearing distant sounds and working in high-noise environments. It’s likely that this little gadget will prove useful well into the future, and could serve others well, too. Wearable notification devices are growing more popular; this OLED ring is a particularly good example. Video after the break.

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No Need For Speed With This Arduino-Based Inkjet Printer

June 13, 2020 by Dan Maloney 17 Comments

When it comes to computers, it seems like the only thing that matters is speed. The more the better, in general, and the same applies to peripherals. We want the fastest network adapters, the fastest video card, and the fastest printer. So why in the world would anyone intentionally build a really slow inkjet printer? For art, of course.

At least that’s the story [HomoFaciens] tells us in the video below. His efforts are in support of a friend’s art project, which seeks to print slowly but continuously on a roll of paper. [HomoFaciens]’s printer is based on an H-P C6602 inkjet cartridge, one of those high-priced consumables that make buying a new printer more attractive than replacing them once depleted. After figuring out how to drive the printhead — 5 to 6 μs pulses of 18 volts through a ULN2803 Darlington array driver chip seemed to do the trick — he mounted everything to the gantry of an old 3D printer. It’s interesting to watch the images slowly being built up — something that printers usually hide from prying eyes — and to see how the DPI count of the printer can be increased by interlacing each printed line.

Near the end of the video, we get a glimpse of his “tattoo gun printer”, which reminded us of all the other cool things he’s done over the years. From a CNC machine made from paperclips and cardboard to an encoder made from a wheel of resistors, [HomoFaciens] has some interesting designs that you really should check out.

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