Gyrotheodolite is a theodolite with a gyroscope device used to measure the true north azimuth of the line. It is an instrument combining gyroscope and theodolite through a connecting mechanism to measure the true north azimuth. It uses the physical characteristics of the gyroscope itself (fixed axis and precession), and uses the sensitive part of the gyroscope with the center of gravity moving down to be sensitive to the horizontal component of the earth's rotation angular velocity. Under the action of gravity, a precession moment to the north is generated, so that the gyroscope main shaft swings back and forth around the meridional plane of the earth, so as to measure the true north azimuth. Gyro theodolite is widely used in mine survey, engineering survey and military survey. It is also an important auxiliary equipment for radar antenna orientation, UAV flight orientation, artillery and long-range weapon launching orientation.
The application of gyrotheodolite
1.Tunnel centerline measurement
In tunnels and other excavation projects, the center line measurement in the pit generally adopts the long distance traverse which is difficult to ensure the accuracy, especially in the case of shield excavation. Starting from the short reference center line of the vertical pit, the accuracy of Angle measurement and station shifting must be very high. In the measurement, the corresponding inspection of ground and underground should be carried out frequently to ensure the accuracy of measurement. Especially in dense urban areas, inspection conditions are difficult and it is impossible to conduct excessive inspection operations. If the gyrotheodolite can be used to obtain the absolute high accuracy of the bearing datum, and can reduce the cost of high detection operations (minimum checkpoint), it is a high efficiency of the center line measurement method.
2.To obtain the direction Angle when the vision is impaired
When the directional Angle cannot be obtained from a known point due to the obstruction of sight, it can be obtained by means of astronomical survey or gyrotheodolite survey. Compared with astronomical measurement, the gyro theodolite measurement method has many advantages: less dependence on weather, no complicated astronomical calculation, can be obtained in the field of any measurement line direction Angle and easy to calculate the closure difference.
3.The true north measurement required for the calculation of the solar shadow
In urban or suburban areas, there are height restrictions on tall buildings with sun or shadow conditions. The shadow chart should be attached to the building application. This solar shadow map is based on the true solar time of the winter solstice from 8:00 to 16:00 to determine the true north direction with high accuracy for calculation and cartographic purposes. At this time the use of gyro theodolite measurement can not be affected by weather, time, etc.
Limitations in the application of gyrotheodolite
Gyro-theodolites are primarily used in the absence of astronomical star sights and GPS. For example, where a conduit must pass under a river, a vertical shaft on each side of the river might be connected by a horizontal tunnel. A gyro-theodolite can be operated at the surface and then again at the foot of the shafts to identify the directions needed to tunnel between the base of the two shafts. During the construction of the Channel Tunnel, which runs under the English Channel from France to the UK, gyro-theodolites were used to align the tunnels.
Although a gyro-theodolite functions at the equator and in both the northern and southern hemispheres, it cannot be used at either the North Pole or South Pole, where the Earth's axis is precisely perpendicular to the horizontal axis of the spinner and the meridian is undefined. Gyro-theodolites are not normally used within about 15 degrees of the pole because the east-west component of the Earth’s rotation is insufficient to obtain reliable results.Unlike an artificial horizon or inertial navigation system, a gyro-theodolite cannot be relocated while it is operating. It must be restarted again at each site.
When available, astronomical star sights are able to give the meridian bearing to better than one hundred times the accuracy of the gyro-theodolite. Where this extra precision is not required, the gyro-theodolite is able to produce a result quickly without the need for night observations.
More Technical Questions
1.Do You Know the Application of Gyro Theodolite ?
2.What is the Structure of a Gyro Theodolite?
3.Gyroscope in Gyro Theodolite
4.A Brief Description of the Gyro Theodolite
5.What Is The Orientation Principle Of A Gyrotheodolite?
6.The Gyrotheodolite is Precisely Oriented
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