A Second Chance For The Single Wheel Monorail?

August 16, 2025 by Heidi Ulrich 27 Comments

Lately, this peculiar little single wheel monorail came to our attention. Built by [extraglide1976], all from Meccano. His build started with modest tests: one gyro obviously flopped. Two gyros geared together ran slightly better. But when he adds active gimbal control, things suddenly come to life – the model shudders, catches itself, and carries on. The final green-roofed locomotive, with LEDs signalling ‘system go’, trundles smoothly along a single rail on [extraglide1976]’s deck.

To be fair, it houses a lot of mechanics and engineering which we don’t find in the monorails of today. We do have quite a few monorails in our world, but none of them balance on a single wheel like this one. So, where did this invention derail?

Outside of theme parks, Japan is one of the few countries where monorails are still used as serious urban transport: though Germany’s century-old Wuppertal Schwebebahn, the lesser-known C-Bahn, China’s sprawling Chongqing and Shanghai systems, Malaysia’s Kuala Lumpur line, Brazil’s São Paulo network, the US links in Seattle and Las Vegas, and India’s Mumbai Monorail prove the idea has quietly taken root elsewhere.

The thing you’ll see in nearly all these monorails is how the carriages are designed to clamp onto the tracks. This is of course the most safe option, but it loses out on speed to the ones that sit on top of the tracks, balancing on one wheel. Such a train was actually invented, in 1910, by Louis Brennan. His original monorail promised faster, cheaper transport, even using existing rails. The carriages leaned into turns like a motorbike, without any intervention from the driver. Two counter-rotating gyroscopes kept the carriage upright, cancelling precession forces like a mechanical Jedi trick.

Back then, it failed commercially, but today? With cheap sensors, brushless motors, and microcontrollers, and intelligent software, why not let it make a comeback? It could carry freight through narrow urban tunnels. With high-speed single-rail pods?

Investors killed Brennan’s idea, but we live in a different time now. You could start out with a gimmicky ‘snacks and beer’ highline from your fridge to your garage. Share your take on it in the comments!

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ASUS GPU Uses Gyroscope To Warn For Sagging Cards

April 28, 2025 by Maya Posch 51 Comments

It’s not really an understatement to say that over the years videocards (GPUs) — much like CPU coolers — have become rather chonky. Unfortunately, the PCIe slots they plug into were never designed with multi-kilogram cards in mind. All this extra weight is of course happily affected by gravity.

The problem has gotten to the point that the ASUS ROG Astral RTX 5090 card added a Bosch Sensortec BMI323 inertial measurement unit (IMU) to provide an accelerometer and angular rate (gyroscope) measurements, as reported by [Uniko’s Hardware] (in Chinese, see English [Videocardz] article).

There are so-called anti-sag brackets that provide structural support to the top of the GPU where it isn’t normally secured. But since this card weighs in at over 6 pounds (3 kilograms) for the air cooled model, it appears the bracket wasn’t enough, and active monitoring was necessary.

The software allows you to set a sag angle at which you receive a notification, which would presumably either allow you to turn off the system and readjust the GPU, or be forewarned when it is about to rip itself loose from the PCIe slot and crash to the bottom of the case.

Chaotic System Cooks Meat Evenly

December 11, 2024 by Bryan Cockfield 35 Comments

For better or worse, a lot of human technology is confined to fewer dimensions than the three we can theoretically move about in. Cars and trains only travel two dimensionally with limited exceptions, maps and books generally don’t take advantage of a third dimension, and most computer displays and even the chips that make them work are largely two-dimensional in nature. Most styles of cooking can only apply heat in a single dimension as well, but [Dane Kouttron] wanted to make sure the meat his cookouts took advantage of a truly three-dimensional cooking style by adding a gyroscopic mechanism to the spit.

The first thing that needed to be built were a series of concentric rings for each of the three axes of rotation. Metal tubes were shaped with a pipe bender and then welded into their final forms, with an annealing step to flatten the loops. From there, the rings are attached to each other with a series of offset bearings. The outer tube is mounted above the fire and a single motor spins this tube. Since no piece of meat is perfectly symmetrical (and could be offset on the interior ring a bit even if it were) enough chaos is introduced to the system that the meat is free to rotate in any direction, change direction at any time, and overall get cooked in a more uniform way than a traditional single-dimensional rotating spit.

As a proof of concept [Dane] hosted a cookout and made “gyro” sandwiches (even though the machine may technically be more akin to a gimbal), complete with small Greek flag decorative garnishes. It seems to have been a tremendous success as well. There are a few other novel ways we’ve seen of cooking food over the years, including projects that cook with plasma and much more widely available methods that cook food efficiently using magnets, of a sort.

Combining Gyro Stabilisation With Weight Shift Balancing

November 1, 2024 by Danie Conradie 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.

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The Gyro Monorail: How To Make Trains Better With A Gyroscope

January 31, 2024 by Maya Posch 11 Comments

The gyroscopic system for gyro monorail trains that Brennan developed. (Credit: Primal Space)

Everyone who has ever handled a spinning gyroscope found themselves likely mesmerized by the way it absolutely maintains its orientation even when disturbed. Much of modern technology would be impossible without them, whether space telescopes or avionics. Yet during the early 20th century a much more radical idea was proposed for gyroscopes, one that would essentially have turned entire trains into gyroscopes. This was the concept of the Gyro Monorail, with Louis Brennan being among those who built a full-sized, working prototype in 1910, with its history and fate covered in detail by [Primal Space], along with an accompanying video.

At first glance it may seem rather daft to have an entire train balancing on a single rail track, using nothing but gyroscopic forces to keep the entire contraption level and balanced even when you feel the thing should just tip over. Yet the gyroscopic system that Brennan created and patented in 1903 turned out to function really well, and reliably kept the train on its single track. Key to this was the use of two gyroscopic wheels, each spinning in an opposite direction, with a pneumatic system linked to a gear system between the two wheels that used the gyroscope’s precession in corners to quickly establish a new balance.

Despite this success, investors were unconvinced, and regular trains were already firmly established, and the system would also require that each car had its own gyro system. Even so, the idea of the gyro monorail never truly died, as evidenced by the recently created German MonoCab-OWL project. This targets converting single-rail sections into dual-rail, bi-directional service with no infrastructure investment required.

Thanks to [Stephen Walters] for the tip.

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Teardown Of Two Russian Missile Sensors

January 5, 2024 by Maya Posch 22 Comments

Recently [Michel] received two packages from Ukraine containing some salvaged Russian electronics that once belonged to (presumably) a 9K38 Igla, Vympel R-27 or similar infrared homing missile, as well as a Fiber Optic Gyroscope (FOG) from an unknown missile, though possibly from the Tornado family of MRLSes. The latter uses the Sagnac effect to detect the phase shift between two laser beams being injected into the same fiber when the fiber, and thus the device, are rotating. The advantage of such a gyroscope is that it is effectively solid-state, requiring only some optical components, amplifier stage and as shown here an Altera Cyclone II FPGA to integrate the results.

The 16-channel linear infrared array sensor is more basic, with a matching amplification channel for each optical receiver element, which are fed into a multiplexer IC in a rather remarkable looking ceramic-gold packaged DIP format, with what looks like a 2004 date code (‘0424’). Although both are rather damaged, [Michel] figures that he might be able to restore the FOG to working condition, assuming no crucial and irreplaceable parts are missing. As useful as FOGs are in missiles, they also have countless uses outside of military applications.

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Fancy Gyroscopes Are Key To Radio-Free Navigation

November 1, 2023 by Lewin Day 49 Comments

Back in the old days, finding out your location on Earth was a pretty involved endeavor. You had to look at stars, use fancy gimballed equipment to track your motion, or simply be able to track your steps really really well. Eventually, GPS would come along and make all that a bit redundant for a lot of use cases. That was all well and good, until it started getting jammed all over the place to frustrate militaries using super-accurate satellite-guided weapons.

Today, there’s a great desire for more accurate navigational methods that don’t require outside communications that can easily be jammed. High-tech gyroscopes have long been a big part of that effort, allowing the construction of inertial navigation systems with greater accuracy than ever before.

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