# Method of determining initial position of inertia block with respect to base coordinate system

FIELD: instrument industry.

SUBSTANCE: method comprises autonomous determination of the position of the instrument with respect to the horizontal plane coordinate system from the signals from the accelerometers and vector conforming of the coordinate systems for determining the position of the instrument coordinate system in azimuth.

EFFECT: enhanced precision.

1 dwg

The invention relates to the field of instrumentation and can be used to create inertial control systems to determine the navigation parameters controlled moving objects using a strapdown inertial navigation system (bins).

Known methods for determining the navigation parameters when using strapdown inertial navigation systems (Say, Timberman, Imoke. "Determination of the orientation parameters of the object strapdown inertial system" - SPB: SSC RF - CSRI "Elektropribor" 1996; Saizew, Aielines, Fuimicino, Allegiance, Hinsurance "method for determining the navigation parameters managed mobile objects and device for its implementation" - application for invention No. 2003114979 from 20.05.2003, IPC G 01 21/24).

One of the most important requirements for strapdown inertial navigation systems, is the need for initial exhibition of the instrument coordinate system (UCS) strapdown inertial block (BIB) relative to the base coordinate system.

The number of ways the exhibition inertial systems described in the book Alpena "Exhibition inertial systems on a movable base". Publishing house "Nauka", Moscow, 1971.

The known method of the exhibition unmanaged mobile object, set the on on the launcher. The initial exhibition of the object is that object together with a launcher with a special device deploy at a given azimuth shooting against a known direction to the North and to the specified elevation angle relative to the known position of the plane of the horizon. Precision shooting unmanaged moving objects does not meet modern requirements.

To improve the accuracy of fire use managed movable objects. Managed mobile objects using strapdown inertial navigation system control. The position of the instrument coordinate system associated with the strapdown inertial unit at the moment to solve the navigation task should be defined relative to the base coordinate system with great precision.

We will use the following coordinate system.

OXYZ is the starting coordinate system.

The OX axis is in the plane of the horizon and rejected from the North by an angle equal to the azimuth of fire.

The OY axis is parallel to the plumb line at the starting point and directed upwards from the Earth's center.

The OZ axis forms with the axes OX and OY, right rectangular coordinate system.

OX_{1}Y_{1}Z_{1}- the coordinate system associated with the object.

The axis OX_{1}directed along the longitudinal axis of the object.

The axis OY_{1}situated in the vertical plane of symmetry of the object.

The axis OZ_{1}forms with the axes OX_{1}and OY_{1}right rectangular coordinate system.

The position of the coordinate system OX_{1}Y_{1}Z_{1}is relative stable platform cursortype (KB) according to the signals from the angle sensors installed on the axes Kardanov suspension. Stable platform cursortheme materializes basic (initial) coordinate system.

OX_{n}Y_{n}Z_{n}- the instrument coordinate system that is defined by the mounting surface strapdown inertial unit. The instrument coordinate system OX_{n}Y_{n}Z_{n}in an "ideal" case must match the system OX_{1}Y_{1}Z_{1}. In the General case, the axes of these coordinate systems do not coincide with each other and their mutual position must be specified.

It is obvious that the initial exhibition BIB relative to the base coordinate system can determine if to make an exhibition of the instrument coordinate system BIB for the building of the axes of the object and to provide the positioning and construction of the axes of the object relative to the base coordinate system with the required accuracy.

For solving the problem of the initial exhibition BIB is proposed to use the well-known method of vector matching coordinate systems. To implement this method, you must determine not menuduh non-collinear vectors, which can be measured in the instrument and the base coordinate system (Averincev, Spicco, Aiguesmortes. Gyroscopic system. M: mechanical engineering, 1983).

The proposed method, for enhancing the accuracy of the initial exhibition of the instrument coordinate system BIB relative to the base starting coordinate system, involves the use of testimony sensitive elements BIB and cursortype (KB).

In strapdown inertial navigation systems as sensitive elements BIB uses accelerometers to measure the vector of the apparent acceleration and angular velocity sensors (Dosy) to measure the absolute angular velocity of the controlled object.

The drawing shows the layout on the launcher (1) of the controlled object (4), strapdown inertial unit (6), side (5) and ground (3) digital computing devices (BCWU, NCVO), cursortype (2), the frame (9) of the device rotate the launcher with the engine rotation azimuth angle (8) and the motor rotation angle of elevation (7).

The offered method is based on measuring the growth projections of the vector of apparent velocity from acceleration of gravity and the projections of the rotation vector launchers) together with BIB. Rotating PU is carried out at angles of azimuth and boswich is of special devices. The angles of rotation PU relatively stable platforms KB are defined in NCVO (3) signals from the angle sensors installed on the axes Kardanov suspension KB, and transferred to BCWU (5). In the process of defining the start of the exhibition is the exchange of necessary information between NCVO, BCWU.

One of the essential requirements of PU is ensuring the rigidity between the housing KB and installation place BIB, i.e. ensuring immobility BIB relatively KV.

The accuracy of exhibitions in the stillness of the BIB on Earth will be determined by the accuracy of determining the orientation associated with the housing cursortheme coordinate system relative to the base system and the accuracy of the sensing element BIB. The influence of external noise (wind, vibrations of soils and other) on the accuracy of determining the start of the exhibition can be reduced by using known filtering methods.

The proposed combined method the initial exhibition of the instrument coordinate system BIB combines offline method for determining the vertical space on the signals of the accelerometers BIB and nonautonomous method of determining azimuth method vector matching coordinate systems according to the signals of the accelerometers and angular velocity sensors BIB and the signals of the angle sensors cursortype. The method is distinguished by the combination of following the x main features:

- the use of testimony sensitive elements BIB and KB;

- formation of the projections of the rotation vector PU and growth projections videoconferencing;

- specification of the initial exhibition of the readings of the accelerometers BIB.

The method consists of performing the following operations.

The signals from the sensors of angular velocity BIB (6) in BCWU (5) for some time-reversal BIB (6) together with PU (1) solve the matrix equation Poissonwherethe angular velocity vector, S(t) is the rotation matrix.

The increment of the matrix C(t) for time reversal PU (1) determine BCWU (5) the angle of the rotation vector BIB (6) with respect to inertial space and its projection on the axis of the instrument coordinate system.

The signals of the accelerometers BIB (6) determine BCWU (5) increment projections of the apparent velocity vector (VCS) on the axis of the instrument coordinate system for some time hold PU (1) stationary relative to the Earth and determine the direction of the vertical.

By the values of the angles obtained by the signals from the angle sensors KB (2) at the start and end of turn PU (1), determine the rotation matrix associated coordinate system, relative to stable platforms KB (2).

Projected growth of video conferencing on the axis of the base coordinate system for the retention time of PU (1) in the still is able relative to the Earth and the rotation matrix for the coordinate system, associated with the housing KB (2)determine BCWU (5) increment projections of video conferencing on the axis of the coordinate system associated with the housing KB (2).

The rotation matrix corps KB (2) its relatively stable platform and the rotation matrix stabilized platform relative to inertial space during reversal PU (1) determine BCWU (5) the angle of the rotation vector of the coordinate system associated with the housing KB (2), relative to inertial space and its projection on the axis of the coordinate system associated with the housing KB (2).

On the obtained values of the increments projections VCS and the rotation vector on the axis of the associated and instrument coordinate systems defined in BCWU (5) the angular position of the instrument coordinate system relative to the associated coordinate system and relative to the base coordinate system.

The signals of the accelerometers BIB (6) specify BCWU (5) the angular position of the instrument coordinate system relative to the vertical space of the exhibition.

By appropriate software turns PU (1) it is possible to generate multiple non-collinear vectors reversal PU (1) and several non-collinear vectors increments of videoconferencing in the instrument and related coordinate systems. Any combination of pairs from this set of vectors can uniquely determine the initial orientation of the instrument coordinate system relative to the base.

Using the two proposed technical solution is achieved by reducing the time and increasing the accuracy of the initial exhibition of the instrument coordinate system relative to the base system, what is the technical result of the present invention. The proposed method can also be used when calibrating sensors BIB.

In the drawing:

1 - launcher (PU);

2 - curculation (KB);

3 - terrestrial digital computing device (NCVO);

4 - the managed object (UO);

5 - Board digital computing device (BCWU);

6 - strapdown inertial block (BIB);

7 - engine speed VS angle of elevation;

8 - engine speed VS angle of azimuth;

9 - frame device rotation PU;

OXYZ is the starting coordinate system;

OX_{p}Y_{p}Z_{p}- the instrument coordinate system;

OX_{1}Y_{1}Z_{1}- associated with a managed object coordinate system.

The method of determining the initial exhibition of the instrument coordinate system strapdown inertial unit of a managed object that is installed on the launcher relative to the base (initial) coordinate system, materialized stable platform cursortype, also installed on the launcher, which in turn, together with a launcher of a managed object at the desired elevation angle and azimuth, characterized in that

the signals from the sensors of angular velocity strapdown inertia inogo unit in the computing device during turn launchers form the rotation matrix and determine the angle of the rotation vector strapdown inertial unit relative to inertial space and its projection on the axis of the instrument coordinate system;

the signals of the accelerometers strapdown inertial unit in stationary relative to the Earth position is determined in a digital computing device increment projections of the vector of apparent velocity on the axis of the instrument coordinate system and angles vertically relative to the instrument coordinate system;

the signals from the angle sensors cursortheme in the computing device determines the rotation matrix associated coordinate system relative to the stabilized platform cursortype;

projected increment vector apparent velocity on the axis of the base coordinate system and the rotation matrix associated coordinate system relative to the stabilized platform determine the increment vector of apparent velocity on the axis of the associated coordinate system;

the rotation matrix of the coupled system is relatively stable platform and the rotation matrix stabilized platform relative to inertial space determine the angle of the rotation vector associated system with respect to inertial space and its projection on the axis of the associated coordinate system;

on the obtained values of the increments of the projection vectors of the rotation and apparent velocity determine the angular position of the instrument system to the ordinate relative to the base system;

the signals of the accelerometers specify the position of the instrument coordinate system relative to the vertical space of the exhibition.

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