Actively Balancing A Robot With A Gyroscope

Self-balancing robots are a common hacker project, but we don’t often see them using spinning gyroscopes to achieve that balance. Robot master [James Bruton] decided to build a robotic platform with active gyroscopic stabilization, starting from a simple proof of concept.

A gyroscope can balance, but cannot actively counteract external forces directly. However, if the gyroscope is tilted around an axis it will exert a force perpendicular to that axis of tilt, known as gyroscopic precession. By tilting the gyroscope with an actuator, and orienting the gyroscope correctly, gyroscopic precession can be used for stabilization. This is known as a control moment gyroscope. [James] demonstrated this with a 3D printed proof of concept, which is used as an IMU to measure the angle of tilt, and use a PID loop to correct the imbalance with a servo actuating the gyroscope.

His second platform used a pair of gyroscopes spinning in opposite directions to compensate for any unintended gyroscopic precession along another axis. A pair of roller skate wheels allow the entire platform to roll along. Due to a slight imbalance in the platform, [James] noticed that the gyroscopes will continue to creep in one direction, until reaching the end-stops and falling over. By adding a second software controller to keep track of how much the gyroscopes have to move to maintain balance, it can continuously calculate and update the balancing point. This prevents the gyroscopes from hitting the end stops.

Control moment gyroscopes are commonly used for attitude control on spacecraft, and to reduce the rolling motion of boats in waves. [James] has plans to combine a control moment gyroscope with the more conventional balancing method, to balance a robot on a single wheel.

We’ve seen a two wheeled RC cars use gyroscopes before, but without the active control part.

9 thoughts on “Actively Balancing A Robot With A Gyroscope

  1. Very interesting to see double gyroscope balancing in action. Somewhere in my library there’s a novel from before WWI with a fictional tale of a young man driving a two-wheeled gyrocar through Albania. It didn’t describe how its two large gyros were arranged, so the flight of fancy did not go far toward practicality. In fact it seemed to assume that balance would be achieved simply by spinning them up, sans actuator and control system.

      1. Yes, but fully open, two-seater boat-like body, no training wheels, and no stand auto-retract, as far as I recall.
        Also, the Gyro-X was actually produced. It would have been very interesting to see its balancing gear.

      1. Yes, except that the vehicle had a boat shaped body, was amphibious, and seated two side by side. It was pretty James Bondish for around 1900 or so. (No publishing date in the book, sadly, so I can only go by the pre WWI world view exposited.) The book’s paper is also old.

      1. For high speed travel a monorail like this really makes a lot of sense, compared to the complexity of the tilting carriage having your monorail lean into a curve is quite elegant.

        1. There are other advantages. A single rail is both cheaper and simpler to install than parallel rails. And it can follow a tighter radius, so it would be ideal for temporary rails or mountainous terrain. On the other hand, you need stabilization both on the engine and on each carriage, and you need both a system to ensure that the gyroscopes maintain power if the engine loses power, or a strategy to “land” the train in case of a failure. Not easy to do 100 years ago, a lot simpler to achieve now. Another issue is that while having fewer wheels on the rail reduces friction further, it also makes it harder to brake and accelerate, so it’s not really ideal for high speed trains.

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