You don't necessarily need to feel alien towards such devices, examples of gyroscopes can be seen on a daily basis almost anywhere, starting from toys like the yo-yos and Powerballs all the way to the common bicycle, vehicles in general, ships or even space telescopes and air planes. A basic gyroscope represents a device that measures and helps maintain orientation in space, since it will remain oriented in the same direction regardless of the motion of the platform it is mounted on.
It works on the principle of conservation of angular momentum, and consists of a spinning
wheel supported on an axis that is free to move on its own. The spinning wheel, or rotor, is mounted on a pivoting support that allows the rotation around a single axis, called a gimbal. By using two gimbals at a time, one mounted inside the other, the gyroscope gives the rotor three degrees of rotational freedom.
Some of the first gyroscopes have been created in 1817, by Johann Bohnenberger. 'The Machine', as Bohnenberger called it, quickly fell into Leon Foucault's attention, who used it, in 1852, in an experiment studying the rotation of the Earth, which also gave the device its current name. However, the experiment received no valuable scientific interest, mostly because of the fact that the friction limited the spin of the rotor to about 8 to 10 minutes, insignificant time to make accurate measurements.
The breakthrough came in the 1860s, once with the development of the first electric engines, which led to the invention of the first gyrocompasses, devices that can be used much in the same way as regular magnetic compasses. Since then,
the basic design of the gyroscopes and the gyrocompasses haven't changed very much. A revolutionary new gyroscope has only been created recently, by using Micro Electro-Mechanical Systems that work by measuring the oscillation of a vibrating element. Others spin the rotor in a volume of fluid, in order to get rid of the gimbals, which may interfere with the correct functioning of the device from time to time.
For example, gyroscopes using gimbals can experience a so-called gimbal lock, meaning that two of the three gimbals are basically located in the same plane, causing an inability to determine the platform's orientation in space. Knowing that gyroscopes are used routinely in airplanes, such a gimble lock can cause a catastrophic failure in maintaining direction, which could ultimately lead to air accidents. To resolve such problems, engineers prefer to reduce the possibility of a gimble lock by adding a fourth one.
Gyroscopes experience a number of unique behaviors, such as precession and nutation. A gyroscope device supported loosely at one end would describe a circular motion, instead of just falling under the influence of gravity. The increase in precession is directly related to the spin of the rotor, meaning that, once the rotor slows its spin rate, the circle described by the gyroscope grows in length, until it reaches a maximum and the device falls under the influence of gravity, as it is no longer able to support its own weight.
As long as the rotor of the gyroscope is being spun, the gyroscope will keep pointing in the same direction. Gyroscopes are mostly used as a basis for inertial navigation systems, meaning that with the help of three very sensitive accelerometers one can detect the motion of the vehicle on which the gyroscope is mounted, on all three axes.