RU2641515C2 - Method for construction of astroinercial navigation system - Google Patents

Abstract

FIELD: tool engineering.

SUBSTANCE: star pair is selected that is available line-of-sight view at a given object location and at a given point in time, their Cartesian coordinates are determined in projection on the axis of accompanying trihedral, and the angles for teleblock aiming thereon, subsequent sighting of star with determination of its actual coordinates, that are translated into adjustable system errors. At the star sighting stage, the base of the teleblock is installed in the plane of local horizon. On the axis of the accompanying trihedral, the Cartesian coordinates of the star are redesigned on the axis of the basic instrument trihedral by multiplying the vector of its Cartesian coordinates by transposed matrix of orientation matrix of the sighting object, and the angles of teleblock aiming are calculated by obtained Cartesian coordinates in the projections on the instrument trihedron axis that are used as a target indication when sighting the star.

EFFECT: improved accuracy of astrovision.

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Description

The invention relates to the field of instrumentation, namely to high-precision integrated navigation systems using astrometry, and is used as a part of on-board equipment of aerospace objects.

From the existing level of technology there is a known method for constructing an astroinertial navigation system (AINS), implemented, for example, in the domestic L14MA system, which is part of the navigation aerobatic complex (NPK) installed on a Tu-95MS aircraft (Cherenkov S.A., Chesnokov G.I. Jubilee All-Russian Scientific and Technical Conference in honor of the 65th anniversary of the Moscow Institute of Electromechanics and Automatics “Navigation and Control of Aircraft” (MIEA Proceedings, Issue 12), Moscow, 2016, pp. 34-35), as well as in foreign analogues, e.g. system NAS-26 (Northrop Corporation, Electronics Division, Hawthorno, California, ADA 090649, 1980).

Each of the above AINS has a gimbal suspension, which includes an external roll frame and an internal gyro platform pitch frame, on which system accelerometers are installed, providing a plane of the physical local horizon. To work out the angles of targeting the target axis of the teleblock to the selected astro landmark, the teleblock is placed in the frame of the gimbal, a repeater of the plane of the physical local horizon connected by analog or optical tracking systems with the gimbal of the gyro platform. The coordinates of the selected star (target angles) are calculated in the axes lying in the plane of the local horizon, and are issued from the onboard digital computer as target designation by targeting systems that work out these target designations to the target axis of the teleblock.

, где х₁, х₂, x₃ - декартовы координаты звезды в проекциях на оси сопровождающего трехгранника. Связь между углами нацеливания визирной оси телеблока и декартовыми координатами орта, совпадающего с линией визирования звезды, определяется исключительно схемой карданова подвеса телеблока и кинематикой отработки его углов - А и В. Рассмотрим для определенности азимутально-высотный карданов подвес, при котором наведение на звезду осуществляется разворотом телеблока в азимуте от оси Ox₁ на угол А (азимут - угол, отсчитываемый в плоскости местного горизонта от северного направления меридиана против часовой стрелки) и по высоте на угол В (высота - угол, отсчитываемый от плоскости местного горизонта до линии визирования звезды).So, for example, we define the Cartesian coordinates of the sighted star as a vector

, where x ₁ , x ₂ , x ₃ are the Cartesian coordinates of the star in the projections on the axis of the accompanying trihedron. The relationship between the target angles of the teleblock’s sight axis and the Cartesian coordinates of the unit vector, which coincides with the star’s line of sight, is determined solely by the teleblock gimbal’s gimbal and the kinematics of working out its angles — A and B. For definiteness, we consider the azimuth-altitude gimbal gimbal, in which the star is rotated by turning the teleblock in azimuth from the axis Ox ₁ to angle A (azimuth is the angle measured counterclockwise in the plane of the local horizon from the northern direction of the meridian) and in height by angle B (height is the angle measured from the plane of the local horizon to the line of sight of the star).

The relationship between the Cartesian coordinates of the star and the angles A, B of the tele-turn is defined as

Where from

-TgA = x ₂ / x ₁ ,

where x ₁ , x ₂ , x ₃ are the Cartesian coordinates of the star in the projections on the axis of the accompanying trihedron.

The disadvantages of the known system include the following.

The presence of a gimbal framework - a repeater of the horizon plane leads to a significant increase in the dimensions of the device and an increase in its weight. So, the mass of the L14MA system is about 220 kg.

The total error in the sighting of the selected star is made up of errors in the tracking systems that ensure the horizon is built by the repeater, and errors in the tracking systems that ensure the teleblock is displayed according to the target designation issued from the on-board computer.

When solving the problem of building an AINS by replacing a platform inertial navigation system (ANN) with a strap-on one (SINS), options are possible related to the specifics of building an INS — the absence of a gimbal that provides the construction of a physical local horizon.

The L14MA system, in which the gyro platform (PG-3) is replaced by SINS, is taken as the basis for the implementation of one of these options for constructing AINS; at the same time, the analogue tracking systems that provide repeater leveling are replaced with digital tracking systems that work out the horizon using digital codes for heading angles, roll and pitch, coming from the SINS output via serial binary code channels (MPC). It is also possible to build an AINS, according to which the on-board BINS digital computer and its program are finalized by digital-to-analog converters (DACs), respectively, and by including in the program a block for calculating Sin and Cos of course angles, roll and pitch, and outputting to the DAC rough and accurate channels of existing tracking systems.

The options discussed above practically do not give any advantages in terms of increasing the accuracy of the system or reducing the overall weight and weight characteristics, since the structure of the system itself, and, in particular, the horizon plane follower, are preserved.

In the patent of the Russian Federation No. 2442108, G01C 21/00, 10.27.2010, AINS is considered, in which analog tracking systems that provide communication between the gyroplatform and the frames of the gimbal suspension - horizon repeater, are replaced by optical tracking systems that provide communication between the block of sensitive elements (BEC) SINS and target axis of the teleblock. In this case, there is no need for a gimbal frame - a repeater of the horizon plane, which will entail a decrease in the overall weight characteristics of the device. However, with such an arrangement of the device, the multilevel structure of the connection between the target axis of the teleblock and the sensitivity axes of the corrected system remains, i.e. there remains the problem of the connection between the target axis of the tabloc and the prisms of the optical tracking system and the connection of these prisms with the sensitivity axes of the accelerometers of the corrected system, i.e. A potential increase in accuracy can be achieved only through the use of more accurate optical tracking systems that provide teleblock stabilization in the plane of the local horizon.

As a prototype, the AINS construction method implemented in the L-41 serial astroinertial system (Cherenkov S.A., Chesnokov G.I. Anniversary All-Russian Scientific and Technical Conference in honor of the 65th anniversary of the Moscow Institute of Electromechanics and Automatics “Navigation and Control of Aircraft” "(Proceedings of the Moscow Institute of International Economics, issue 12), Moscow, 2016, p. 34-35).

In the known method, the use of a single-axis sighting device in the AB1CM teleblock allowed us to construct a binding scheme to the basic control element (BKE), representing a 72-facet prism, directly by the teleblock, which is used to sight stars, which made it possible to exclude intermediate elements in optical communication, namely, a plane repeater horizon, thereby increasing the accuracy of sighting stars.

In the known cardan method, the teleblock suspension provides three degrees of freedom - the teleblock is rotated around two horizontal axes and around a vertical axis in azimuth. The use of the console diagram of the teleblock gimbal suspension provides two measurements when a single star is sighted by a single-axis astro-sensor - the star is sighted when the teleblock rotates to a certain angle in azimuth and the same star is sighted again when the teleblock rotates in azimuth to an angle that differs from the original by 90 °. The use of a three-channel tracking system for working out the azimuthal angle - a coarse channel built on sine-cosine transformers (SKT), for rough working out the angle, an accurate channel built on 32-pole SKT with a reduction coefficient of 32, and an optical channel built on rotating optical wedges with a reduction coefficient of 72, - it was possible to obtain the accuracy of working out the azimuthal angle of the order of units of arc seconds.

In addition, the use of the same sensitive element, namely the target axis of the teleblock (in this case, the star’s sight and the binding to one of the selected faces of the BKE, is used during measurements (determining the coordinates of the sighted star and determining the errors of reference to the base instrument coordinate system) in the same plane), allowed to exclude such structural errors of the device as the noncollinearity and non-orthogonality of the axes of the cardan of the teleblock and the axes of the basic instrument trihedron, since the obtained measurements Phenomena are defined as the angle of sight of the star minus the angle obtained in the BKE reference mode.

The disadvantage of this method is the lack of accuracy of astrovization. Since the practical production of a 72-sided prism is practically impossible, all faces of the prism are partized with respect to the initial zero face of the prism, and corrections for orientation errors of these faces are recorded in read-only memory (ROM) and are algorithmically taken into account in the work program. Thus, the complex task of linking the target axis of the teleblock is reduced to binding the normal of the initial (zero) face of the BKE to the base frame of reference of the instrument trihedron.

An object of the invention is to increase the accuracy of astrovization.

The indicated technical problem is solved thanks to the method of constructing an astroinertial navigation system, which consists in selecting a star that is available for sighting at a given location of the sighting object at a given moment in time, calculating its Cartesian coordinates in the projections on the axis of the accompanying trihedron, and the teleblock pointing angles on it, then sighting the star with the determination of its actual coordinates, which are converted into errors of the corrected system, while at the stage of sighting the stars, the base The eblock is set in the plane of the local horizon, and the Cartesian coordinates of the star defined in the projections on the axis of the accompanying trihedron are redesigned on the axis of the base instrument trihedron by multiplying the vector of its Cartesian coordinates by the transposed orientation matrix of the sighting object, and the angles of orientation are calculated from the obtained Cartesian coordinates in the projections on the axis of the trihedral teleblock, which are used as target designation for sighting a star.

In accordance with the proposed method for constructing an astroinertial navigation system, the Cartesian coordinates of the unit vector, which coincides with the line of sight of the selected star, are determined in the axes of the accompanying trihedron by being redesigned on the axis of the base instrument trihedron by multiplying them by the transposed Euler-Krylov orientation matrix, which is a function of the roll angles, pitch and and calculated in the work program BINS calculator in accordance with the formula

- орт, совпадающий с линией визирования звезды, определенный в проекциях на оси базового приборного трехгранника;Where

- the unit vector, which coincides with the line of sight of the star, defined in the projections on the axis of the base instrument trihedron;

And ^t is the transposed orientation matrix;

x is the vector of the Cartesian coordinates of the star in the projections on the axis of the accompanying trihedron.

The relationship between the basic instrument and the accompanying trihedra is determined by three consecutive turns of the accompanying trihedron by the course angle ψ around the Ox ₃ axis, by the pitch angle υ around the Ox ₂ axis, by the roll angle γ around the Ox ₁ axis, which corresponds to the sequential multiplication of matrices

where A is the orientation matrix;

Ψ is the matrix of the turn of the accompanying trihedron to the heading angle ψ;

υ is the matrix of the rotation of the accompanying trihedron by the pitch angle υ;

G is the matrix of the turn of the accompanying trihedron by the angle of heel γ.

From here we get

In this case, the tilt angles of the teleblock (for the considered azimuth-altitude suspension) are determined as

Thus, according to the proposed method, the teleblock turning angles are determined taking into account the device’s rotation and, accordingly, the gimbal of the teleblock in space relative to the local horizon, which eliminates the need to install the gimbal - the repeater of the plane of the local horizon and thereby increases the accuracy of star sighting by eliminating the intermediate channel mining horizon tracking systems without complicating the overall design of the device. Instrumental errors in the mutual alignment of the teleblock sighting axis with the coordinate system of the base instrument trihedron are determined on goniometric measuring stands during bench tests and are taken into account as compensation corrections in working algorithms and programs.

The structure of the astroinertial system that implements the proposed method, structurally includes an astroizing device 1 and a hardware-connected digital computer 2 (on-board computer) that receives signals from the consumer and implements BINS algorithms (Fig. 1). The astroizing device includes a teleblock 3, servo systems implemented as a gimbal drive control unit for pointing the teleblock to astro-landmark 4, connected to the teleblock 3 by its output, and the input to the calculator 2, the sensor unit BINS 5, including a triaxial block micromechanical gyroscopes 6 with a block of accelerometers 7, as well as a block for measuring the angular position of the astroizing device 8, connected by their outputs to the corresponding inputs of the calculator 2. Astroizing device onstruktivno 9 consists of a platform with detecting astroorientir teleblokom 2 mounted thereon and BCHE BINS 5 - triaxial unit micromechanical gyros and 6 accelerometers unit 7 (Figure 1, 2.). The platform 9 is mounted in an azimuth-high gimbal suspension, which includes an external roll frame 10 that rotates relative to the frame, and a rotationally internal pitch frame 11 connected to it, by which the platform 9 can rotate in bearings along the pitch and roll axes. The platform 9 is rigidly connected to the inner frame of the pitch 11 and is installed along a vertical line, which the optical axis of the teleblock 3 is ideally collinear.

Thus, the teleblock and sensitive elements of the BSE BINS are installed on a single platform so that the sensitivity axes of gyroscopes and accelerometers are rigidly connected with the axis of working off the teleblock pointing angles, as a result of which targeting of the teleblock pointing angles are formed in the axes of the base instrument trihedral according to the information about heading angles and pitch obtained with SINS. This scheme reduces the number of channels of tracking systems in block 4 by eliminating the channels of tracking systems for mining the horizon, which can potentially improve the accuracy of astrovization.

The claimed method is as follows.

The transmitter 2 of the astronautical system receives information from the consumer (navigation and sighting system) about the location of the object, the date and time of the location of the object at a particular point. The calculator solves the navigation equations in the "Exhibition" mode and in the "Navigation" mode using the sensitive elements of the BINS BINS 5 located on the gimbal of the teleblock 3. In the "Astronavigation" mode, the calculator solves the problem of selecting an astronomical point using signals from the BINS BINS sensors. When generating control signals for the gimbal drives control unit for pointing the teleblock to the selected astro-landmark, as well as accompanying this astro-landmark, the same sensitive elements of the BINS BINS are used, which eliminates the errors of reference to the base instrument coordinate system, and, therefore, improves the accuracy astrovization.

Claims (1)

A method of constructing an astroinertial navigation system, which consists in choosing a star that is available for sighting at a given point of the location of the sighting object at a given time, calculating its Cartesian coordinates in the projections on the axis of the accompanying trihedron and the teleblock pointing angles on it, then sighting the star with determining its actual coordinates, which are converted into errors of the corrected system, while at the stage of sighting the star, the base of the teleblock is set in the plane of the local horizon nt, characterized in that the Cartesian coordinates of the star defined in the projections on the axis of the accompanying trihedron are re-projected onto the axis of the base instrument trihedron by multiplying the vector of its Cartesian coordinates by the transposed orientation matrix of the sighting object, and the telelock pointing angles are calculated from the Cartesian coordinates in the projections on the axis of the instrument trihedral which are used as target designation for star sighting.

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