Horizon (reference)
An artificial horizon plane is necessary for numerous measuring instruments so that the measured elevation angles or height differences relate exactly to the horizontal. The plane of this reference horizon is also called the mathematical horizon and is at right angles to the vertical direction at the position of the observer.
Without this correcting horizon reference, the measurements would be falsified, since the standing axis inclination of the measuring instrument deviates from the ideal vertical position.
technical realization
The most important of the technical possibilities for establishing this reference to the mathematical horizon are:
- a pendulum body , which when the instrument is at rest - within the scope of its mechanical precision - adjusts itself to the plumb line . However, when cornering or turning , the centrifugal force distracts it.
- In geodetic measurement technology, the axis inclination is taken into account by so-called compensators as inclinometers,
- with geodetic precision theodolites and with total stations often by a mechanical height compensator ,
- with automatic leveling devices by a hanging prism that deflects the beam path,
- in flight navigation by a sextant suspended in a pendulous manner .
- a tube vial on precise spirit levels, the gas bubble of which settles in the liquid-filled tube at the highest point. The measurement can then be reduced
- take place automatically (e.g. by refraction of light in the gas bubble)
- or manually, for example in the case of the marine sextant by reflecting it into the measuring telescope or in the case of the building theodolite by looking at the insurance vial
- a liquid horizon through which the sighting axis of the measuring telescope is steered so
- with some theodolites (e.g. core DKM2 ) with an oily liquid,
- in astrometry with a mercury horizon , for example in some prism astrolabes .
Other uses
Horizon sensors are also used in modern construction vehicles (excavators) and cranes , for example to control vertical gripping movements. In Land Cruisers they serve u. a. for determining the slope of the terrain or for checking the fuel supply.
See also
Literature and web links
- Wolf von Fabeck : gyroscopes. The different types of devices and their technical applications. Principle-related errors and technical solutions. Physical basics. Vogel, Würzburg 1980, ISBN 3-8023-0612-0 .
- Heribert Kahmen : Surveyors. 19th, revised edition. de Gruyter, Berlin et al. 1997, ISBN 3-11-015399-8 .
- Wolfgang Torge : Geodesy. 2nd, completely revised and expanded edition. de Gruyter, Berlin et al. 2003, ISBN 3-11-017545-2 .
- Control for a hydraulic round shell grab