Author: Danie Conradie

431 Articles

A Surprisingly Simple Omnidirectional Display

November 22, 2024 by 34 Comments

Old-school technology can spark surprising innovations. By combining the vintage zoetrope concept with digital displays, [Mike Ando] created the Andotrope, a surprisingly simple omnidirectional display.

Unlike other 3D displays, the Andotrope lets you view a normal 2D video or images that appear identical irrespective of your viewing angle. The prototype demonstrated in the video below consists of a single smart phone and a black cylinder spinning at 1,800 RPM. A narrow slit in front of each display creates a “scanning” view that our brain interprets as a complete image, thanks to persistence of vision. [Mike] has also created larger version with a higher frame rate, by mounting two tablets back-to-back.

Surprisingly, the Andotrope appears to be an original implementation, and neither [Mike] nor we can find any similar devices with a digital display. We did cover one that used a paper printout in a a similar fashion. [Mike] is currently patenting his design, seeing the potential for smaller displays that need multi-angle visibility. The high rotational speed creates significant centrifugal force, which might limit the size of installations. Critically, display selection matters — any screen flicker becomes glaringly obvious at speed.

This device might be the first of its kind, but we’ve seen plenty of zoetropes over the years, including ones with digital displays or ingenious time-stretching tricks. Continue reading “A Surprisingly Simple Omnidirectional Display” →

Tearing Down A SLA Printer With The Engineers Who Built It

November 18, 2024 by 1 Comment

Product teardowns are great, but getting an unfiltered one from the people who actually designed and built the product is a rare treat. In the lengthy video after the break, former Formlabs engineer [Shane Wighton] tears down the Form 4 SLA printer while [Alec Rudd], the engineering lead for the project, answers all his prying questions.

[Shane] was part of the team that brought all Form 4’s predecessors to life, so he’s intimately familiar with the challenges of developing such a complex product. This means he can spot the small design details that most people would miss, and dive into the story behind each one. These include the hinges and poka-yoke (error-proofing) designed into the lid, the leveling features in the build-plate mount, the complex prototyping challenges behind the LCD panel and backlight, and the mounting features incorporated into every component.

A considerable portion of the engineering effort went into mitigating all the ways things could go wrong in production, shipping, and operation. The fact that most of the parts on the Form 4 are user-replaceable makes this even harder. It’s apparent that both engineers speak from a deep well of hard-earned experience, and it’s well worth the watch if you dream of bringing a physical product to market.

You probably know [Shane] from his YouTube channel Stuff Made Here. We’ve covered many of his ludicrously challenging projects, like the auto-aiming pool cue and golf club, a robotic hairdresser, and an “unpickable” lock.

Continue reading “Tearing Down A SLA Printer With The Engineers Who Built It” →

A Very Fast Camera Slider For The Glam Shot

November 18, 2024 by 7 Comments

High-speed photography with the camera on a fast-moving robot arm has become all the rage at red-carpet events, but this GlamBOT setup comes with a hefty price tag. To get similar visual effects on a much lower budget [Henry Kidman] built a large, very fast camera slider. As is usually the case with such projects, it’s harder than it seems.

The original GlamBOT has a full 6 degrees of freedom, but many of the shots it’s famous for are just a slightly curved path between two points. That curve adds a few zeros to the required budget, so a straight slider was deemed good enough for [Henry]’s purposes. The first remaining challenge is speed. V1 one used linear rails made from shower curtain rails, with 3D printed sliders driven by a large stepper motor via a belt. The stepper motor wasn’t powerful enough to achieve the desired acceleration, so [Henry] upgraded to a more powerful 6 hp servo motor.

Unfortunately, the MDF and 3D-printed frame components were not rigid enough for the upgraded torque. It caused several crashes into the ends of the frame as the belt slipped and failed to stop the camera platform. The frame was rebuilt from steel, with square tubing for the rails and steel plates for the brackets. It provided the required rigidity, but the welding had warped the rails which led to a bumpy ride for the camera so he had to use active stabilization on the gimbal and camera. This project was filled with setback and challenges, but in the end the results look very promising with great slow motion shots on a mock red carpet.

We’ve seen DIY camera sliders of all shapes and sizes, including ones made from skateboard trucks and wood, and even a measuring tape.

Continue reading “A Very Fast Camera Slider For The Glam Shot” →

Automated Weed Spraying Drone Needs No Human Intervention

November 11, 2024 by 4 Comments

Battling weeds can be expensive, labor intensive and use large amounts of chemicals. To help make this easier [NathanBuilds] has developed  V2 of his open-source drone weed spraying system, complete with automated battery swaps, herbicide refills, and an AI vision system for weed identification.

The drone has a 3D printed frame, doubling as a chemical reservoir. V1 used a off-the-shelf frame, with separate tank. Surprisingly, it doesn’t look like [Nathan] had issues with leaks between the layer lines. For autonomous missions, it uses ArduPilot running on a PixHawk, coupled with RTK GPS for cm-level accuracy and a LiDAR altimeter. [Nathan] demonstrated the system in a field where he is trying to eradicate invasive blackberry bushes while minimizing the effect on the native prairie grass. He uses a custom image classification model running on a Raspberry Pi Zero, which only switches on the sprayers when it sees blackberry bushes in the frame. The Raspberry Pi Global Shutter camera is used to get blur-free images.

At just 305×305 mm (1×1 ft), the drone has limited herbicide capacity, and we expect the flights to be fairly short. For the automated pit stops, the drone lands on a 6×8 ft pad, where a motorized capture system pulls the drone into the reload bay. Here a linear actuator pushes a new battery into the side of the drone while pushing the spend battery one out the other side. The battery unit is a normal LiPo battery in 3D-printed frame. The terminal are connected to copper wire and tape contacts on the outside the battery unit, which connect to matching contacts in the drone and charging receptacles. This means the battery can easily short if it touches a metal surface, but a minor redesign could solve this quickly. There are revolving receptacles on either side of the reload bay, which immediately start charging the battery when ejected from the drone.

Developing a fully integrated system like this is no small task, and it shows a lot of potential. It might look a little rough around the edges, but [Nathan] has released all the design files and detailed video tutorials for all the subsystems, so it’s ready for refinement.

Continue reading “Automated Weed Spraying Drone Needs No Human Intervention” →

Fix That Old Remote With Graphite

November 1, 2024 by 46 Comments

A button that stopped working has probably led to more than a few smashed remotes over the years. Fortunately [pescado99] has shared a beautifully simple cure for dead or dying remote buttons: graphite dry lubricant.

Most remotes operate by pushing a conductive carbon coating on the back of the button onto a pair of contacts on the PCB. Unfortunately, that conductive coating can wear off, leaving you with a dead or dying button. The video after the break [pescado99] demonstrates how to use a cotton swab to apply powdered graphite to the rear of the buttons to make them conductive again. A soft pencil can also be used, but the graphite works better.

This beautifully simple hack is too good not to share and could save many remotes from landfills. If you’re more interested in upgrading remote, you can build your own universal remote or replace it with a web browser.

Continue reading “Fix That Old Remote With Graphite” →

Combining Gyro Stabilisation With Weight Shift Balancing

November 1, 2024 by 4 Comments

Gyroscopes are perfect to damper short impulses of external forces but will eventually succumb if a constant force, like gravity, is applied. Once the axis of rotation of the mass aligns with the axis of the external torque, it goes into the gimbal lock and loses the ability to compensate for the roll on that axis. [Hyperspace Pirate] tackled this challenge on a gyroscopically stabilized RC bike by shifting a weight around to help keep the bike upright.

[Hyperspace Pirate] had previously stabilized a little monorail train with a pair of control moment gyroscopes. They work by actively adjusting the tilt of gyroscopes with a servo to apply a stabilizing torque. On this bike, he decided to use the gyro as a passive roll damper, allowing it to rotate freely on the pitch axis. The bike will still fall over but at a much slower rate, and it buys time for a mass on the end of the servo-actuated arm to shift to the side. This provides a corrective torque and prevents gimbal lock.

[Hyperspace Pirate] does an excellent job of explaining the math and control theory behind the system. He implemented a PD-controller (PID without the integral) on an Arduino, which receives the roll angle (proportional) from the accelerometer on an MPU6050 MEMS sensor and the roll rate (Derivative) from a potentiometer that measures the gyro’s tilt angle. He could have just used the gyroscope output from the MPU6050, but we applaud him for using the actual gyro as a sensor.

Like [Hyperspace Pirate]’s other projects, aesthetics were not a consideration. Instead, he wants to experiment with the idea and learn a few things in the process, which we can support.

Continue reading “Combining Gyro Stabilisation With Weight Shift Balancing” →

Bogey Six O’clock!: The AN/APS-13 Tail Warning Radar

October 31, 2024 by 20 Comments

Although we think of air-to-air radar as a relatively modern invention, it first made its appearance in WWII. Some late war fighters featured the AN/APS-13 Tail Warning Radar to alert the pilot when an enemy fighter was on his tail. In [WWII US Bombers]’ fascinating video we get a deep dive into this fascinating piece of tech that likely saved many allied pilots’ lives.

Fitted to aircraft like the P-51 Mustang and P-47 Thunderbolt, the AN/APS-13 warns the pilot with a light or bell if the aircraft comes within 800 yards from his rear. The system consisted of a 3-element Yagi antenna on the vertical stabilizer, a 410 Mhz transceiver in the fuselage, and a simple control panel with a warning light and bell in the cockpit.

In a dogfight, this allows the pilot to focus on what’s in front of him, as well as helping him determine if he has gotten rid of a pursuer. Since it could not identify the source of the reflection, it would also trigger on friendly aircraft, jettisoned wing tanks, passing flak, and the ground. This last part ended up being useful for safely descending through low-altitude clouds.

This little side effect turned out to have very significant consequences. The nuclear bombs used on Hiroshima and Nagasaki each carried four radar altimeters derived from the AN/APS-13 system.

Continue reading “Bogey Six O’clock!: The AN/APS-13 Tail Warning Radar” →