This miniature monorail stays upright with the help of gyro stabilization

Most monorail systems, like the kind at Disney and in Las Vegas, stay upright because the “rail” is actually a very wide beam. The car’s load tires (often literal truck or trailer tires) roll on top of that beam and guide tires clamp the sides of the beam, preventing the car from getting tippy. But what if the rail were more like a conventional train track? In the case of Hyperspace Pirate’s monorail model, active gyro stabilization is the key.

Nobody has really produced a working full-scale gyroscope-stabilized monorail system since first conceived by Louis Brennan in 1903, because the idea simply isn’t practical at that size. Active gyroscope stabilization requires a lot of energy and is quite complex. If anything goes wrong, disaster is just around the corner. But on a small model scale, such considerations are much less relevant.

Hyperspace Pirate took advantage of that fact to create a shrunken-down version of the 20th century experimental monorail that travels along a 24″ track. It uses a control moment gyroscope (CMG) to keep the car upright on the single narrow rail. A CMG like this one uses a spinning mass’s inertia to resist torque that would change the axis of rotation. If you’ve ever played with one of those gyroscope hand exercise balls, this works in a similar manner. This monorail utilizes two of them to counteract side-to-side tipping, while cancelling out the tendency of them to reduce forward-backward tilting. 

The challenge with this design is that it requires active actuation of the individual CMG flywheels, which is a major reason why it would be impractical at a full-scale. But Hyperspace Pirate was able to solve that problem by using an Arduino Nano board to tilt the spinning flywheels using servo motors. It does so in response to any tipping, which it detects using an MPU6050 IMU sensor. 

With some added outrigger weights, similar to a tightrope-walker’s pole, Hyperspace Pirate was able to build a monorail that seems to work fairly well. 

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