Autonavigator

autonavigator

[¦ȯd·ō′nav·ə‚gād·er]
(navigation)
A navigation system that automatically measures absolute vehicle motions and computes distance and direction from the departure point.

Autonavigator

 

a self-contained aeronautical navigation device that automatically and continuously plots the course (that is, calculates the current coordinates) of an aircraft. Functionally, an autonavigator can be divided into the automatic indicators for the current coordinates that are required for a fix and the programmed navigation automatons that control the flight according to a specified trajectory or specified target. An autonavigator consists of transmitters for the true airspeed and the course, transmitters for the wind velocity and direction, setting mechanisms for the chart angle and coordinates of the target, a computer, and indicators for the assigned and output parameters.

The action of an autonavigator amounts to a continuous time integration by the computer of the aircraft’s ground velocity components. These are equal to the geometric sum of the true airspeed and the wind velocity; this sum provides the measurement of the distance covered toward the target (X) and the lateral deviation from the assigned route (Y) in the conventional coordinate system OXY, which is rotated with respect to the geographical coordinate system by the chart angle ψ0. Before a flight, the coordinates of takeoff locality—the latitude ø0 and the longitude λ0—are inserted in the autonavigator. During the flight, the autonavigator continuously measures the vector of the true air speed V and the true course ψ. The wind velocity U and its direction, the angle δ, are determined periodically and fed into the autonavigator manually or automatically.

Since the operating principle of an autonavigator is based on an indirect method of measurement, there are present, in addition to instrumental errors, systematic errors. The latter make it advisable to include along with an autonavigator other airborne navigation systems (inertial, radio, and so forth). In the literature, an autonavigator is also called a navigation automaton for aerial dead reckoning and a navigation coordinator. The first autonavigator in the USSR was proposed by V. Iu. Poliak in 1930.

REFERENCE

Seleznev, V. P. Navigatsionnye ustroistva. Moscow, 1961.

A. L.GORELIK

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