RU2654932C1 - Device for determining astronomical coordinates of an object - Google Patents

Abstract

FIELD: information technology.

SUBSTANCE: invention can be used to test and configure mobile devices used in self-contained navigation systems. Device includes an optical unit with three rigidly bounded reflective faces, two are inclined, one is vertical, an autocollimation block containing a lens, a test object and a reference node, reflective horizon optically connected to a first reflective inclined face and to the lens to which a second reflective inclined face is connected, a third face is perpendicular to an optical axis of the lens. Optical block is made up of two rigidly bonded base prism faces. One of the prisms, AP-90°, has a support face facing the reflective horizon, and a base face facing the lens. Second prism is made with an angle α between the reflective and base faces. Ratio of dimensions of the reflecting faces of the prisms is chosen from the condition of equal echo intensity. Main sections of the prisms lie in one plane perpendicular to a plane of the reflective horizon and passing through an optical axis of the lens.

EFFECT: determination with high accuracy in real time of the angular coordinates of objects and astronomical coordinates at an observation point in conditions of limited access to a stationary geodetic network and unstable observation conditions.

1 cl, 2 dwg, 1 ex

Description

The invention relates to measuring equipment, in particular to angle measuring devices used to determine the astronomical coordinates of objects, in particular, the direction of the meridian passing through the observation point. The device can be used to test and configure mobile devices used in stand-alone navigation systems.

Currently known angle measuring instruments are widely used for measuring the coordinates of objects located on the earth’s surface, with reference to the geodetic network [1], in navigation systems for various purposes, including spacecraft [2], for engineering and geodetic works in construction engineering structures and equipment installation [3].

Known, for example, angle measuring device [Pat. RF №2442109, IPC G01C 21/24, 06/09/2010], containing a stellar channel lens, in the focal plane of which a matrix radiation detector is installed connected to the computing unit, a radiation input device into the stellar channel lens, while the stellar channel lens provides the formation of the first point image from an astronomical radiation source on the matrix radiation receiver, and the input device of radiation into the lens of the stellar channel and the lens of the stellar channel carry out the formation of the second point image eniya from said astronomical radiation source on the matrix radiation receiver. Moreover, to increase the illumination in the second point image from an astronomical radiation source on the matrix of the receiving device, the radiation input device into the lens of the stellar channel can be made in the form of a transparent plane-parallel plate with a beam-splitting reflective coating. The main disadvantage of such a device is the inability to work with non-radiating objects, for example, mirrors, unlit brands and signs installed on objects whose coordinates must be determined.

Closest to the claimed device in terms of essential features is a device for determining astronomical coordinates [A.S. USSR No. 1585681, IPC G01C 1/00, 05.06.87,] containing an optical unit mounted on the base with three rigidly interconnected reflecting faces, two of which are inclined, one is a vertical, liquid horizon, an autocollimation unit in the form of a telescope with the test object, the axis of rotation and the reference node, while the liquid horizon is optically paired with the first reflective oblique face of the optical element and with the telescope with which the second reflective oblique face is paired.

The disadvantage of this device is the "limited scope" due to the inability to work simultaneously with several objects, such as a luminary and a mark or a sign installed on earthly objects, as well as insufficient accuracy due to the large number of operations that must be performed to determine the direction to the luminary .

A device is proposed for determining the astronomical coordinates of an object, which allows real-time determination of the angular coordinates of moving and stationary objects of observation with high accuracy and thereby the astronomical coordinates at the observation point under conditions of limited access to a stationary geodetic network and unstable observation conditions.

Such a technical effect is achieved when the device for determining the astronomical coordinates of an object, including an optical unit mounted on the base with three reflective faces rigidly connected to each other, two of which are inclined, one is a vertical, autocollimation unit containing a lens, a test object, and a reference unit , the reflective horizon optically conjugated to the first reflective inclined face of the optical unit and to the lens, which, in turn, is associated with the second reflective inclined face, and t this face is installed perpendicular to the optical axis of the lens, it is new that the optical unit is made up of two prisms rigidly connected by base faces, one of which is made in the form of an AP-90 ° prism and has a support face facing towards 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 is the latitude of the area where measurements are taken, deg;

u is the angle of the field of view of the lens, deg;

the ratio of the sizes of the reflecting faces of the prisms is selected from the condition of ensuring equal intensity of the reflected signals, the basic faces of the prisms are connected so that the main sections of both prisms lie in one plane perpendicular to the plane of the reflecting horizon and passing through the optical axis of the prism lens, and the reference unit is made in the form matrix receiving device connected to a computing unit associated with an accurate time sensor.

The basis of the invention is the definition in the horizontal plane at the observation point of the direction of the meridian, as the projection onto the horizontal plane of the vertical plane passing through the zenith at the observation point and the pole of the world, defined as the center of the trajectory of the observed object.

In FIG. 1 shows a device for determining the astronomical coordinates of an object in a section by a plane coinciding with the plane of the main sections of the prisms and passing through the optical axis of the lens, where the optical unit, consisting of prism 1, prism 2, reflective horizon 3, lens 4, autocollimation block with mark 5, illuminator 6, matrix receiving device 7, beam splitter 8, computing unit 9, accurate time sensor 10, setting tables 11, 12, quotation units 13, 14, 15 base 16, test object 17;

A is the base face of the prisms;

B - reference face of the prisms;

α is the angle at the apex of the second prism, deg .;

- направление хода лучей;

- the direction of the rays;

* - the light.

In FIG. 2 shows a diagram of directions in the horizontal plane at the observation point, where

N - direction to the sun;

About - the direction of the target axis of the device;

M _N — direction to the north;

P is the projection of the pole of the world;

Z - observation point, zenith projection;

A is the base face of the prisms;

A _N - azimuth of the star;

An is the azimuth of the device.

In solving a number of topographic, geodesic, and navigation problems, astronomical observations of celestial bodies, the coordinates of which are known at a certain time in a certain coordinate system, are widely used to determine the geographical coordinates of terrestrial objects. In one of the azimuthal methods for determining geographic coordinates, the latitude and longitude of the observation point is determined from the measured differences in the azimuths of stars at known points in time. It is known that in order to ensure the most favorable conditions for observations that allow achieving the maximum accuracy in determining the values, it is necessary to use near-pole stars for observation. In the northern hemisphere, the North Star meets this criterion.

The proposed device operates as follows.

At the observation point (point Z in Fig. 2) in the horizontal plane constructed using lens 4, prisms 1 (A is the base face of the prisms in Fig. 2) and reflective horizon 3, the position of the device’s sight axis is determined in a horizontal circle. In FIG. 2, this direction is designated as “O”. The line of sight is one of the coordinate axes of the device in a rectangular coordinate system.

The determination of the azimuthal angle of the North Star (N is the direction to the star in Fig. 2) using the computing unit 9 is carried out continuously, synchronously with the accurate time sensor 10. The measurement is carried out relative to the sighting axis of the device passing through 0 of the coordinate system of the matrix of the receiving device 7.

In order to determine the angular deviation of the sighting axis of the device from the north direction (M _N in Fig. 2), using the computing unit 9 determine the position of the center of the path of the Polar Star image in the plane of the receiving device matrix (point P in Fig. 2), for this, for 2-3 hours of observation time take at least 5 points on the trajectory and calculate the coordinates of the trajectory using one of the known methods [4].

In preparation for operation, an optical unit containing a prism 1 with a prism 2 rigidly connected to it with an angle α and a lens 4 with a focal unit using quotation units 12 and 13 are mounted relative to each other so that the autocollimation image of brand 5 from the base surface of the prism 1 will fall into the center of the matrix of the receiving device 7. The relative position of the optical unit and the lens 4 with the focal unit is fixed using the clamping elements of the quotation units 12 and 13.

During measurements, the base 16 is installed in a horizontal plane in the direction of the pole (in this case, the north) with an accuracy of (0.5-1) angular minutes with an azimuth opposite to the azimuth of the star, in this case, the North Star. Moving the device in the horizontal plane, they get the image of the North Star on the matrix in the quadrant that corresponds to the time of observation of the star (this is known from the observation tables). After that, using the quotation nodes 15, the device is set so that the center of the autocollimation image of brand 5 from the reflection horizon 3 falls into the center of coordinates of the matrix of the receiving device 7. This coincidence of two autocollimation images of brand 5 indicates that the sighting axis of the device is horizontal and coincides with one of the axes of a rectangular coordinate system in which measurements are made of the astronomical coordinates of the body.

A parallel light beam emitted by the North Star, reflected from the inclined face of the prism 2, enters the field of view of the lens 4, which forms the image of the star on the matrix surface of the receiving device 7.

Using the computing unit 9, the coordinates of the center of the image of the Polar Star are determined, which, together with the time data of the observation moment coming from the exact time sensor 10, are used to calculate the astronomical azimuth of the Polar Star and the direction of the meridian (see, for example, [4]). (The Appendix provides a developed method for determining the coordinates of the center of the path of the body and, accordingly, the direction of the meridian at the point of observation of the body).

After that, an autocollimation image of the signal from the control element of the tested navigation device 17 is obtained on the matrix of the receiving device 7, as a rule, this is an autocollimation image of brand 5.

If the task is to adjust the navigation device, then comparing the X coordinate of the image center of the autocollimation signal and the pole, determine the magnitude of the azimuthal correction, which is entered into the navigation device 17.

The proposed device allows to increase the accuracy of determining the astronomical coordinates of objects due to the following factors.

A new constructive solution of the optical unit and its optical conjugation with the lens with a focal unit and a reflective horizon allows us to simultaneously observe the plane of the horizon and the location of the body during a session with the test object, which allows us to assess the stability of the position of the target axis of the device relative to the meridian and, if necessary, make adjustments by reducing the influence of non-stationary factors, such as changes in temperature, air flow, vibration on the measurement results.

The proposed constructive solution of the optical unit can also significantly reduce the effect of manufacturing errors of prisms, such as errors in angular dimensions, pyramidality of prisms that directly affect the measurement result. This is achieved during the assembly of the optical unit by controlling the location of the main sections of prisms 1 and 2 and rigidly fixing them using optical contact or gluing. The value of the residual error of the angles is certified and taken into account as corrections in the calculations.

Combining the vertical plane passing through the sight axis of the device with the meridian plane allows you to get rid of errors like parallax associated with observing an object from different points or recalculating its position in different coordinate systems.

In the design of the device there are no moving units and parts used directly in the measurement process, therefore there are no measurement errors associated with their typical errors: gaps in the guides, uneven travel, friction, etc.

Ways to reduce the influence of random factors associated with instability of observation conditions (atmospheric distortion, vibration, etc.) are known and based on the use of special devices (astroilluminators, optical fibers), mathematical statistical methods for processing the results of observations, and increasing the speed of electronic elements and devices.

Assessment of the accuracy of determining the direction of the meridian.

The assessment was made on the assumption that the center of the image of the star was determined without errors and the shape of the diffraction spot of the scattering image of the star does not change during movement along the trajectory.

1. The optical unit is made without errors, the angles of the prisms are within tolerances. The trajectory of the North Star is the circle, tan α1 tan α2 = -1 [6], R = 10 mm. Focal length of the lens = 700 mm. (Hereinafter, all linear quantities in millimeters).

First step

Second step

Third step

Fourth step

Fifth step

2. The trajectory of the motion of the North Star is an ellipse, tan α1 tan α2 = - (cos u) ² , as a consequence, the nonorthogonality of the axis of the light beam to the plane of the matrix of the receiving device.

The semi-major axis of the ellipse a = r / cos u, the semi-minor axis of the ellipse b = r, b = 10 mm, u = 1.5 °. Focal length of the lens = 700 mm.

First step

Second step

Third step

Fourth step

Fifth step

Thus, we can conclude that after three hours of observing the luminary, the calculation of the direction of the meridian can be made with an accuracy of the order of hundredths of an arc second.

Based on the foregoing, the assessment of the total error in determining the azimuthal coordinates of the object using the proposed device is not more than 0.2-0.3 ".

Literature

1. Kuznetsov PN, Vasyutinsky I.Yu., Yambaev Kh.K. Geodetic Instrumentation: A Textbook for Universities.- M .: Nedra, 1984.

2. Kolosov M.P. Optics of adaptive goniometers. Introduction to Design: Monograph. M., Logos, 2011.

3. Yambaev Kh.K. Special geodetic instruments for engineering and geodetic works. - M .: Nedra, 1990.

4. S.S. Urals. Course of geodetic astronomy. Textbook for high schools. M., "Nedra", 1980.

5. I.I. Privalov. Analytic geometry. Textbook for high schools. M., "Science" 1964.

6. M.Ya. Vygodsky. Handbook of Higher Mathematics. M., "Science", 1969.

application

A method for determining the coordinates of the center of the path of the body and, accordingly, the direction of the meridian at the point of observation of the body

The image of the North Star during measurements continuously moves into the field of view of the lens of the device.

This trajectory in a rectangular coordinate system can be represented as a system of equations

Y = r cosωt,

X = r sinωt,

where t is the time of day

ω is the speed of rotation of the Earth around its axis,

r is the radius of the trajectory in the calculated position, defined as the product of the azimuthal angle of the star in radians and the focus of the lens,

In the process of measurement, the coordinates of the center of the image of the star, on the matrix of the receiving device, are read in synchronously with the signals of the exact time. Approaches to determining the center of the image are known. Moreover, in each measurement step, the following calculations are performed:

- determination of the coordinates of the middle of the chord connecting the first point on the trajectory of the body with the second, then the first with the third, etc .;

- determination of tgα1, where α1 is the angle in degrees between the straight line passing through these points and the axis of the receiver matrix passing through the large axis of the ellipse, as the ratio of the increment of the X and Y coordinates relative to the coordinates of the first observation point;

- determination of tgα2, where α2 is the angle in degrees between the straight line passing through the middle of the chord connecting the two centers of the image of the body, and the center of the path along which the image of the body is moving, and the same axis of the receiver matrix.

These two angles α1 and α2 are connected by the relation:

tan α1 tan α2 = -1, which corresponds to a circle [5].

Solving a system of equations at each measurement step

(Us1-Ur) = tgα2 (Xc1-XP)

(Ycn-Ur) = tgα2 (Xcn-XP), where

Xc1 - abscissa of the middle of the first segment,

Us1 - the ordinate of the middle of the first segment,

Хр - abscissa of the center of the trajectory,

Ur - the ordinate of the center of the trajectory,

1 ÷ n - the number of the point located in the middle of the segment,

find the coordinates of the center of the trajectory Хр and Ур, along which the luminary moves [6].

Then the coordinates Xp and Yp are averaged, for example by the least squares method.

After the azimuthal values of the northward direction and the synchronous azimuthal positions of the North Star are determined, the known relations given in [4] are used to determine the coordinates.

Claims (5)

A device for determining the astronomical coordinates of an object, including an optical unit mounted on the base with three reflecting faces rigidly interconnected, two of which are inclined, one is a vertical, autocollimation unit containing a lens, a test object and a reference unit, a reflective horizon optically coupled to the first reflective oblique face of the optical unit and with the lens, which, in turn, is paired with the second reflective oblique face, the third face is mounted perpendicular to the optical a specific axis of the lens, characterized in that the optical unit is made up of two prisms rigidly connected with the base faces, one of which is made in the form of an AP-90 ° prism and has a support face that faces toward the reflective horizon and a base face that faces towards 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 is the latitude of the area where measurements are taken, deg; u is the angle of the field of view of the lens, deg; the ratio of the sizes of the reflecting faces of the prisms is chosen from the condition of equal intensity of the reflected signals, the basic faces of the prisms are connected so that the main sections of both prisms lie in one plane perpendicular to the plane of the reflecting horizon and passing through the optical axis of the lens, and the reading unit is made in the form of a matrix receiver a device connected to a computing unit associated with an accurate time sensor.

Images