RU2800187C1 - Device for determining astronomical azimuth - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: optical-mechanical measuring device for astronomical and geodetic purposes that can be used for high-precision determination of the astronomical azimuth of a given direction, necessary for testing and configuring mobile devices used in solving navigation problems. The device for measuring the astronomical azimuth contains a computing device, an autocollimator sight, a highly sensitive television camera of which is synchronized with an accurate time sensor, and control module element optically coupled to the autocollimator sight with a biaxial horizon sensor mounted on it. At the same time, a mark transfer lens is used as part of the autocollimator sight, and the control element module is made of a rigidly connected sighting prism, the angle of inclination of which is invariant with respect to the latitude of the location, and a two-sided vertical mirror having central holes of different diameters coaxial with the optical axis of the lens.

EFFECT: increased accuracy and efficiency of determining the astronomical azimuth, as well as standardization when using the device at different latitudes.

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Description

The invention relates to measuring optical-mechanical devices for astronomical and geodetic purposes and can be used for highly accurate determination of the astronomical azimuth of a given direction in order to standardize mobile devices used in solving navigation problems.

The analogue of the invention is the axial meridian circle (Pinigin G.I. Telescopes of ground-based optical astrometry // Tutorial. Nikolaev: Atoll, 2000, p. 64-76), which is a meridian tool with a horizontal pipe, the sighting axis of which is located in the first vertical. The lens of the tube is rigidly connected to the optical unit in the form of a prism (cube, ekker, mirror). The reflective (diagonal) surface of the optical unit is inclined at an angle of 45° to the sighting axis of the pipe. To observe a star in the meridian, the tube, together with the optical assembly, rotates in lagers around its axis by means of a pointing mechanism, setting itself according to the zenith distance so that the image of the star, after reflection from the diagonal surface of the optical assembly, enters the ocular micrometer. At the same time, the image of the light mark of a stationary long-focus collimator (targets) is also transmitted there through a translucent optical unit or a central hole in it. By measuring the distance between the images of the star and the worlds in an ocular micrometer, it is possible to constantly control the position of each star relative to the horizontal reference direction set by a long-focus collimator. The axial meridian circle is an astrometric tool and is not intended for solving the problems of geodetic astronomy.

The prototype of the invention is a device for determining astronomical coordinates (RF patent No. 2654932), which includes an optical unit mounted on the base with three reflective faces rigidly connected to each other, two of which are inclined, one is vertical, an autocollimation unit containing a lens, a test object and a reference node, a reflective horizon optically conjugated with the first reflective inclined face of the optical block and with the lens, which, in turn, is associated with the second reflective inclined face b, and the third face is set perpendicular to the optical axis of the lens. The optical unit is made as a composite of two rigidly connected base faces of prisms, one of which is made in the form of an AR-90° prism and has a reference face facing the reflective horizon and a base face facing the lens, the second prism is made with an angle α between the reflecting and base faces found from the condition

α=ϕ/2÷((ϕ-u)/2), where

ϕ - latitude of the observation point where measurements are made, deg;

u is the angle of the lens field of view.

In the specified device, the direction of the meridian is determined at the observation point as a projection onto the horizontal plane of the vertical plane passing through the zenith at the observation point and the celestial pole, that is, the center of the trajectory of the near-pole star (Polar Star for the northern hemisphere).

The use of the described device for determining the astronomical azimuth is limited to the following circumstances. The instrumental error will increase significantly at high latitudes, since the height of the near-pole star is approximately equal to the latitude of the observation point. In addition, the possibility of sighting a near-pole star is provided by the angle between the reflecting and base faces of the second prism, therefore, for each observation point located at a new latitude, it is necessary to develop and manufacture an optical unit anew. Also, when processing the results of observation, the angular scale of the image is used, which depends on the focal length of the lens and the size of the decomposition element of the matrix photodetector device (hereinafter referred to as FPU), which requires preliminary calibration of the device to determine.

The technical problem being solved is the improvement of a device designed for high-precision determination of the astronomical azimuth.

Achievable technical result - improving the accuracy and efficiency of determining the astronomical azimuth. In addition, unification is provided when using the device at different latitudes.

The essence of the invention lies in the fact that in the device for determining the astronomical azimuth, containing a computing device; sight-autocollimator (hereinafter - VA), which includes an illuminator, a sighting mark, a beam-splitting prism-cube, a mark transfer lens, a highly sensitive television camera synchronized with a precise time sensor, and a lens optically coupled to a control element unit (hereinafter - BCE), on which a two-axis horizon sensor is installed, to ensure simultaneous control of the positions of its own and external control elements and observation of many stars near the meridian and almucantar with a fixed value m height BCE is made of two rigidly connected and having central holes of different diameters of optical elements coaxial with the optical axis of the lens - a sighting prism, the angle of inclination of which is invariant with respect to the latitude of the location, and a two-sided vertical mirror. In addition, a brand transfer lens is additionally introduced, which provides control of the position of the sighting axis of the device directly in the process of observation. The brand transfer lens is a gluing of two lenses and a triple prism.

The fixed value of the height is set by the angle of inclination to the horizon of the working face of the BKE sighting prism.

An increase in accuracy is provided due to the fact that when determining the astronomical azimuth from observations of stars near Almucantarat with a fixed height value, there is no increase in instrumental error when operating the device at high latitudes, and simultaneous observation of many stars in the frame makes it possible, firstly, to reduce the error in taking readings corresponding to the positions of objects from the matrix FPA, and, secondly, to determine the angular scale of the image directly in the process of observation, that is, to exclude the influence of its change on the final result.

Improving efficiency is ensured both by simultaneous observation of stars and autocollimation responses from internal and external control elements in each frame, and by estimating the angular scale of the image directly in the process of observation, and not by pre-calibrating the device.

Unification is achieved due to the fact that when observing stars near the almucantar with a fixed height, there is no need to develop and manufacture BCE for each observation point (location).

The proposed device is illustrated by the optical functional diagram shown in Fig. 1. In FIG. 2 shows a view of the field of view of the device. In FIG. 3 shows a drawing of the BKE.

The following designations are used in the figures:

1 - VA;

2 - BCE;

3, 4 - biaxial horizon sensors (hereinafter - DG);

5 - exact time sensor;

6 - computing device;

7 - sighting prism BKE;

8 - two-sided vertical BCE mirror;

9 - external control element (ECE);

10 - lens;

11 - highly sensitive television camera;

12 - illuminator;

13 - target mark;

14 - beam-splitting prism-cube;

15 - brand transfer lens;

d1 is the diameter of the central hole of the sighting prism of the BCE;

d2 is the diameter of the central hole of the BCE vertical mirror;

a - the height of the sighting prism;

h is the height of the almucantarata, near which the observation of stars is made.

The operation of the proposed device is as follows.

During observations, VA 1 and BKE 2 are installed on the base in such a way that the VA sighting axis is near the meridian plane.

The formation of images of stars is carried out as follows: the light flux from the starry sky with the help of the working face of the sighting prism BKE 7 (the angle of inclination to the horizon is 90-h/2) is directed to the entrance pupil of the lens 10, which forms an image of the starry sky on the sensitive area of the FPU installed in the television camera 11.

Target mark images are formed as follows:

the illuminator 12 illuminates the sighting mark 13, located in the focal plane of the lens with a beam-splitting prism-cube 14;

objective 10 forms a parallel beam at the exit from the VA, which, having passed through the central hole in the sighting prism 7 BCE 2 and reflected from the inner surface of the vertical mirror 8 BCE, and also having passed through the central holes in the sighting prism and the vertical mirror of the BCE and reflected from the HCE 9, is collected by the lens on the sensitive area of the FPA, forming autocollimation images of the target mark corresponding to the directions of the normals to the inner surface of the vertical mirror 8 BKE and to the surface of the VKE 9 (Fig. 2);

the mark transfer lens 15 forms an image of the target mark on the sensitive area of the FPU, corresponding to the position of the target axis VA (Fig. 2).

In the course of observations, the television camera records frames with reference to the exact time scale implemented by means of the exact time sensor 5. In each frame, images of stars observed near the meridian and almucantarat with a fixed height h are formed, and three images of the sighting mark, one of which corresponds to the position of the sighting axis, and the second and third to the positions of the normals to the inner surface of the vertical mirror 8 BCE and to the surface of the HCE 9 (Fig. 2).

The vertical mirror is two-sided and sets the base direction for both the device itself and external autocollimating goniometers.

The positions of the BCE and the television camera relative to the horizon are controlled by the DG 4 and 3 installed on the BCE and the television camera 11, respectively.

The astronomical azimuths of the outgoing normal directions to the inner surface of the vertical mirror 8 BKE and to the surface of the VKE 9 are determined in the computing device 6 as the sum of the azimuth of the sighting axis and the horizontal angles between the sighting axis BA 1 and the directions of the normals to the inner surface of the vertical mirror 8 BKE and to the surface of the VKE 9, respectively.

The determination of the azimuth of the sighting axis is carried out by a computing device as follows: according to the coordinates of the energy centers of the images of objects registered in the frame and the information of the star catalog, the stars are identified, as a result of which an array of compared coordinates of stars is formed: those determined in the FPU plane and equatorial from the catalog, this array is used to determine the transformation parameters, using which the angular scale of the image is calculated and the coordinates of the FPU point corresponding to the position of the sighting axis are converted into equatorial coordinates, and then taking into account the Greenwich stars time and astronomical coordinates of the observation point into horizontal, that is, into the azimuth and height of the sighting axis.

The horizontal angles between the VA sighting axis and the directions of the normals to the BCE and HCE are determined by the computing device, taking into account the angular scale of the image, by the magnitude of the linear displacements of the autocollimation images of the sighting mark obtained by reflection from the BCE and HCE, relative to the VA sighting axis.

The final value of astronomical azimuths is based on the results of multiple observations.

An example implementation of the proposed device.

The proposed device was created and experimentally tested at the enterprise. The diameters of the central holes coaxial with the optical axis of the lens: in the sighting prism 25 mm, in the double-sided vertical mirror 50 mm, were chosen based on the need to ensure the equality of the brightness of the autocollimation images of the target mark (diameter values can be chosen differently, based on the characteristics of the autocollimator sight and observation conditions). Stars were observed near the meridian and the circle of equal heights h = 40° (the choice of the optimal height was made taking into account the influence of instrumental errors and lateral refraction), i.e. the angle of inclination to the horizon of the working face of the BKE sighting prism became invariant with respect to the latitude of the location and amounted to 70°. Also in the device were used: 20-megapixel CMOS-matrix as FPU; lens with relative aperture 1:7; horizon sensor that allows you to determine the angle of inclination relative to the horizon with a root-mean-square error of not more than 0.2 arc. With.; receiver of signals of satellite navigation systems as an accurate time sensor and a computing device for data processing.

In the process of observations, frames containing images of about 50 objects were recorded every second, of which about 30 stars were identified. When processing the data, the angular scale of the image was estimated, which amounted to 2.169 arc. With. The mean square error in determining the astronomical azimuth during the observation time is not more than 20 minutes. did not exceed 0.5 ar. s., which meets the requirements for the accuracy of standardization of mobile devices used in solving navigation problems.

Thus, the claimed technical result is achieved.

Claims (1)

A device for determining an astronomical azimuth, comprising a computing device, a sighting device-autocollimator, a highly sensitive television camera of which is synchronized with an accurate time sensor, and a control element optically coupled to the sighting device-autocollimator with a biaxial horizon sensor installed on it, characterized in that in order to ensure control of the position of the sighting axis directly in the process of observation, a brand transfer lens is used as part of the sighting device-autocollimator, and to ensure simultaneous control of the positions of its own and external control and observation of many stars near the meridian and almucantarat with a fixed value of the height of the block-control element is made of a rigidly connected sighting prism, the angle of inclination of which is invariant with respect to the latitude of the location, and a two-sided vertical mirror having central holes of different diameters coaxial with the optical axis of the lens.