By Kalwinder KaurJul 26 2013
A gyroscope is a device designed to have a spinning disc or wheel mounted on a base such that its axis can turn freely in one or more directions in order to maintain its orientation regardless of any movement of the base. However, the orientation changes in response to an external torque and in a different direction.
The gyroscope has evolved from technology such as mechanical-inertial spinning devices including gimbals, axles, rotors and other electronic and optical devices. Each component exploits some physical property of the system enabling it to detect rotational velocity about some axis.
Design of Gyroscope
The gyroscope is a massive rotor that is fixed in light supporting rings called gimbals. The gimbals consist of frictionless bearings that isolate the central rotor from outside torques. The axle of the spinning wheel defines the spin axis.
The rotor possesses three degrees of rotational freedom and spins about an axis. It acquires extraordinary stability of balance at high speeds as it maintains the high speed rotation axis of its central rotor.
Working Principle
When the gyroscope is applied with external torques or rotations about the given axis, the orientation can be measured by a precession phenomenon. When an object rotating about an axis is applied with external torque along a direction perpendicular to the rotational axis, the precession occurs.
This rotation about the spin axis is detected and information on this rotation is delivered to a motor or other device that applies torque in an opposite direction thereby canceling the precession and maintaining its orientation.
The precession can also be prevented using two gyroscopes that are arranged perpendicular to each other. The rotation rate can be measured by the pulsation of counteracting torque at constant time intervals.
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Image of a typical gyroscope. Credits: Photos.com.
Optical Gyroscope
There are no moving parts to the optical gyroscope and this instrument does not operate based on the conservation of angular momentum.
They are operated based on the principle of the Sagnac effect. A laser beam is first divided by a mirror with half of this surface covered in silver. The process involve The traverse of two beams in identical paths in opposite directions, and combine at a detector.
During operation, one of the beam paths travels at a greater distance to reach the detector. This difference in path length is detected as a phase shift which is proportional to the angular velocity of the system.
Applications
Gyroscopes are used in compasses for boats, spacecrafts and airplanes. In airplanes, the pitch and orientation of the airplane is measured against the steady spin of the gyroscope.
In spacecrafts, the spinning center of the gyroscope is used as a point of orientation to help navigate the desired target.
Massive gyroscopes are used to stabilize large boats and some satellites. They are also used in guidance systems in some missiles. Other applications of gyroscopes include inertial navigation systems and gyrotheodolites for maintaining direction in tunnel mining.
References
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