Chapter 6. Sensors

6.2. Gyroscope

The gyroscope - a device designed to measure angular velocity and angles of orientation of the body relative to the coordinate system of the body (Fig. 52).

Fig. 52. The angles of roll, pitch and yaw

Gyroscopic sensors on the principle of action can be classified as follows:

  • Mechanical gyroscopes:
    • Rotary,
    • Coriolis or vibration;
  • Optical gyroscopes:
    • Laser
    • Fiber.

Mechanical gyros are the moving parts in the construction of sensors, which are measured by the deviation parameters.

Mechanical spinning gyroscope is symmetrical about the axis of rotation of the mass that rotates on its axis at a certain speed. Placing rotor Cardan suspension provides free rotation in three dimensions (Fig. 53).

Fig. 53. The structure of the mechanical rotor gyroscope

The effect of rotor gyroscope lies in the fact that the axis of the rotor mechanical gyroscope is trying to maintain its original position in space. According axis gyroscope exposed before the flight determine the angles of roll, pitch and yaw. While maneuvering of aircraft the axis of gyroscope rotor remains in its original position and acts as a frame of reference (Fig. 54).

Fig. 54. Application rotor gyroscope for measuring angles

The principle of the Coriolis vibratory gyroscopes or based on measuring the Coriolis acceleration, which is caused by rotation of the body.

Coriolis acceleration occurs during the fast rotation of the body about an axis perpendicular to the plane of motion (Fig. 55). Under the influence of the Coriolis force trajectory of the body is distorted. Acceleration is measured fixation deviation of the moving body from the initial position. The most common measurement principle - capacitive at which the deviation depends on the distance between the capacitor wraps.

Fig. 55. Coriolis acceleration

Development of modern technologies of electronic components can significantly minimize the amount of detail. This led to the creation Micro Electro Mechanical System (MEMS). The main advantage of MEMS devices - its dimensions and weight equipment.

Gyroscopes MEMS - is the mikro-elektro mechanical gyroscopes that embodies microelectronic and micromechanical components for measuring angles and corresponding angular velocities [13, 23].

MEMS gyroscopes main types

  • Tuning fork gyroscopes;
  • Gyroscopes built on the principle of rolling wheels;
  • Type gyroscopes Wine Glass Resonator;
  • Electronic piezo gyros;
  • Quantum gyroscopes.

Optical gyroscopes based on the Sagnac effect in optics. Consider the example of the Sagnac effect a system of mirrors placed in a circle (Fig. 56).

A ray of light from the source (laser) incident on the mirror and re-reflects system mirrors in two opposite directions and recorded photosensitive element. In the case of both stationary stationary beams are the same distance.

Fig. 56. The circular interferometer

When you rotate a circular interferometer around the axis perpendicular to the plane of motion rays beam that goes in the direction of rotation, need more time to undergo ring system mirrors than beam directed against the direction of rotation. This is explained by the disparity of optical path lengths, which pass both rays. Depending on the time of passage defined rotation angle and angular velocity. Depending on the environmental distribution of rays in optical gyroscopes are distinguished laser (beam propagates in the gas, Fig. 57) [6] and fiber (beam propagates in the waveguide, Fig. 58) gyroscopes.

Fig. 57. A laser gyroscope
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Avionics training in details by
Ostroumov IvanOSTROUMOV Ivan, PhD
Associate Professor, www.ostroumov.sciary.com