A microwave imaging setup. On the left is a monitor displaying a monochrome GUI. In the center is the RP2040-based positioning and measurement system, and on the right is a vector network analyzer.

Precise Positioning With The RP2040

January 1, 2024 by 10 Comments

Microwave imaging is similar to CT imaging, but instead of X-rays, the microwaves are used to probe the structure and composition of an object. To facilitate experimentation with microwave imaging, [Zehao Li] and [Kapil Gangwar] developed a system based on the RP2040 to control the height and rotation of a test object.

Their control system has a refreshingly physical user interface—a keypad. The keypad is used to configure the object’s position and the scanning step size, while user menus and the sample position are displayed in a clean and uncluttered interface over VGA. The RP2040 runs a multi-threaded program to handle user input, VGA display, and precise driving of two stepper motors for sample positioning.

The microwave imaging was performed by measuring the RF transmission over 2.5-8 GHz between two Vivaldi antennas on either side of the sample at a variety of angles. 2D cross-sections of the test object were reconstructed in Matlab using filtered back-projection. In this proof-of-concept demonstration, a commercial vector network analyzer was used to collect the data, but one could imagine migrating to a software defined radio (SDR) in the future.

A video demonstrating the system is embedded below the break. If you’re interested in DIY radio imaging, you might be interested in this guide to building your own synthetic aperture radar setup, or this analysis of an automotive radar chip.

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Electroluminescent Surfboard Looks Sharp For Night Surfing

January 1, 2024 by 5 Comments

If you’ve watched Point Break lately, you probably considered the thrill and elation involved in night surfing. If you’ve hung out with a lifeguard, though, you might instead have fretted over the dangers. In any case, it remains a popular pastime, and it’s all the more fun with a light-up surfboard like this one from [Moritz Sivers].

This project came about due to a local tradition for [Moritz], where people often surf at night to avoid the crowded breaks during the day. The build started from scratch, with a foam blank shaped into a compact  design optimized for riversurfing, with three fins set up in a thruster configuration. The back side of the board was given a coat of resin impregnated with glow-in-the-dark pigment such that the entire thing would emit an nice green glow, making it more visible at night. On the top surface, a pocket was cut in the board to host electronics for running an electroluminescent panel, complete with artwork inspired by 2001 – A Space Odyssey. The board was also outlined with EL wire to further improve the look.

[Moritz] has experimented with some neat LED surfboard designs before, too. Video after the break.

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Developing An App For Reduced-Gravity Flying

January 1, 2024 by 19 Comments

You’ve likely heard of the “vomit comet” — an rather graphic nickname for the aircraft used to provide short bursts of near-weightlessness by flying along a parabolic trajectory. They’re used to train astronauts, perform zero-g experiments, and famously let director Ron Howard create the realistic spaceflight scenes for Apollo 13. But you might be surprised to find that, outside of the padding that lines their interior for when the occupants inevitably bump into the walls or ceiling, they aren’t quite as specialized as you might think.

In fact, you can achieve a similar result in a small private aircraft — assuming you’ve got the proper touch on the controls. Which is why [Chaz] has been working on an Android app that assists pilots in finding that sweet spot.

Target trajectory, credit: MikeRun

With his software running, the pilot first puts the plane into a climb, and then noses over and attempts to keep the indicator on the phone’s display green for as long as possible. It’s not easy, but in the video after the break you can see they’re able to pull it off for long enough to get things floating around the cockpit.

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Building A Simple Compressed Air Cannon Is Easy

January 1, 2024 by 33 Comments

The world of warfare was revolutionized by the development of black powder, fireworks, cannons, and the like. You don’t need any of that chemical nonsense to just have fun, though, as this compressed air cannon from [OtisLiu153] demonstrates.

The build uses PVC pipes for both the barrel and the air tank. In the case of the latter, avoiding over-pressurization is key to avoiding injury, though some will say you should simply never build a PVC pipe pressure vessel at all. In this case, [OtisLiu153] strictly recommends 150 psi as a limit, which is nicely within the 280 PSI rating of the 2″ Schedule 40 PVC being used. Though, as they note, the connections in the design aren’t necessarily up to the same rating.

Off-the-shelf couplings are used to piece everything together, with the twin-reservoir design also acting as a useful shoulder mount. Charging the cannon is done via a Schrader valve, as you might find on a bike’s inner tube, and firing is achieved via a ball valve.

Of course, if you build such an air cannon yourself, just be careful with your aim. Video after the break.

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A Deep Dive Into Quadcopter Controls

January 1, 2024 by 3 Comments

In the old days, building a quadcopter or drone required a lot of hacking together of various components from the motors to the batteries and even the control software. Not so much anymore, with quadcopters of all sizes ready to go literally out-of-the-box. While this has resulted in a number of knock-on effects such as FAA regulations for drone pilots, it’s also let us disconnect a little bit from the more interesting control systems these unique aircraft have. A group at Cornell wanted to take a closer look into the control systems for drones and built this one-dimensional quadcopter to experiment with.

The drone is only capable of flying in one dimension to allow the project to more easily fit into the four-week schedule of the class, so it’s restricted to travel along a vertical rod (which also improves the safety of the lab).  The drone knows its current position using an on-board IMU and can be commanded to move to a different position, but it first has to calculate the movements it needs to make as well as making use of a PID control system to make its movements as smooth as possible. The movements are translated into commands to the individual propellers which get their power from a circuit designed from scratch for this build.

All of the components of the project were built specifically for this drone, including the drone platform itself which was 3D printed to hold the microcontroller, motors, and accommodate the rod that allows it to travel up and down. There were some challenges such as having to move the microcontroller off of the platform and boosting the current-handling capacity of the power supply to the motors. Controlling quadcopters, even in just one dimension, is a complex topic when building everything from the ground up, but this guide goes some more of the details of PID controllers and how they help quadcopters maintain their position.

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Wii-Inspired Controller Built Using Raspberry Pi Pico

January 1, 2024 by 2 Comments

We all thought Nintendo was going to change the world of gaming when it released the Wii all those years ago. In the end, it was interesting but not really fundamentally life-changing for most of us. In any case, [Sebastian] and [Gabriel] decided to build a Wii-like controller for their microcontroller class at Cornell.

The build uses a pair of Raspberry Pi Pico microcontrollers, communicating over HC-05 Bluetooth modules. One Pico acts as a controller akin to a Wiimote, while the other runs a basic game and displays it on a screen via VGA output. The controller senses motion thanks to a MPU6050 inertial measurement unit, combining both gyros and accelerometers in all three axes.

The duo demonstrate the hardware by using it as a pointer to play a simple Tic-Tac-Toe game. It’s in no way going to light up the Steam charts, but the project page does go into plenty of useful detail on how everything was implemented. If you want to create your own motion gaming controller, you could do worse than reading up on their work.

We’ve seen some other great examples of motion controls put to good use, like this VR bowling game. Video after the break.

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Frog Boy Color Reimagines The Game Boy Color Hardware From The Ground Up

December 31, 2023 by 13 Comments

Sales figures suggest Nintendo did pretty well with the Game Boy Color during its original run, even if the hardware and visuals feel a tad archaic and limited today. [Chris Hackmann] has taken the Game Boy Color design and reworked it from the ground up as the Frog Boy Color, kitting it out with modern upgrades in a GBA-like form factor while retaining the original hardware underneath.

[Chris] went to the wide-style GBA layout for comfort, which he considers superior to the original rectangular Game Boy format. He iterated through over 50 3D-printed enclosure designs to get the design to work, ensuring that the final housing could be CNC machined. He then set out to trim down the original Game Boy Color circuit layout to cut out hardware he considered unnecessary. The original LCD driver could go, since the Q5 replacement LCD he intended to use didn’t need it, and he also considered the IR port to be surplus to requirements. He also set out to replace the original audio amp with his own stereo design.

The result is a wide-format Game Boy Color with a gorgeous modern LCD, USB-C charging, and excellent compatibility with original games and accessories. Files are on Github if you want to build one yourself. Of course, he’s not the only person working on building the best Game Boy ever, but we always love seeing new work in this space. Video after the break.

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