Gyroscope Technology and Applications
A gyroscope is a device that uses to measure the orientation and angular rate of the vehicle in which, it is placed. A typical gyroscope consist a spinning wheel in which the axis of the rotation is free to assume any position in space by itself. During its operation, this spinning wheel axis orientation is unaffected by rotating the mounted vehicle, based on the conservation of angular momentum principle.
Journey without navigation technology is unimaginable. Gyroscopes can be considered as the heart of the inertial navigation system. The range of gyroscope application include from marine to space vehicles. These gyroscopes are employed in many critical applications like guiding ballistic missiles, stabilizing the vehicles, fire control systems in ships, satellite navigation etc.
There is a wide range of applications of gyroscopes include from under water to space like inertial navigation systems, such as in the Hubble telescope, or inside the steel hull of a submerged submarine. Due to their precision, gyroscopes are also used in gyro the odolites to maintain direction in tunnel mining. Gyroscopes can also be used to construct gyrocompasses, which complement magnetic compasses (in ships, aircraft and spacecraft, vehicles in general), to assist in stability (bicycles, motorcycles, and ships) or be used as part of an inertial guidance system.
A Typical gyroscope
A typical gyroscope has a wheel mounted in two or three gimbals, which are pivoted supports that allow the rotation of the wheel about a single axis. These set of gimbals are mounted one on the other with orthogonal pivot axes, may be used to allow a wheel mounted on the innermost gimbal to have an orientation remaining independent of the orientation, in space, of its support. In the case of a gyroscope with two gimbals, the outer gimbal is the gyroscope frame, and is mounted so as to pivot about an axis in its own plane determined by the support. This outer gimbal possesses one degree of rotational freedom and its axis possesses none. The inner gimbal is mounted to gyroscope frame so as to pivot about an axis in its own plane that is always perpendicular to the pivotal axis of the gyroscope frame (outer gimbal). This inner gimbal has two degrees of rotational freedom. The axle of the spinning wheel defines the spin axis. The rotor is constrained to spin about an axis, which is always perpendicular to the axis of the inner gimbal. So the rotor possesses three degrees of rotational freedom and its axis possesses two. The wheel responds to a force applied to the input axis by a reaction force to the output axis.
A Dynamically tuned gyroscope
A Dynamically tuned gyroscope (DTG) is a rotor suspended by a universal joint with flexure pivots. The flexure spring stiffness is independent of spin rate. However, the dynamic inertia from the gimbals provides negative spring stiffness proportional to the square of the spin speed. Therefore, at a particular speed, called the tuning speed, the two moments cancel each other, freeing the rotor from torque, a necessary condition for an ideal gyroscope.
A dynamically tuned gyroscope comprises of a rotor, flexures, gimbals, and a shaft driven by a motor. The main parameters are the moments of inertia of the gimbals, the torsional spring stiffness’s of the flexures, and the spin speed. The gimbals shape need not be a ring, but it should be a regular shape, to make the calculations easy, with a polar inertia Cg and transverse inertias Ag and Bg.