RU2439498C1 - Complex inertial-satellite navigation system - Google Patents

Abstract

FIELD: instrument making.

SUBSTANCE: navigation system comprises units of angular speed sensors and sensors of linear acceleration, which via appropriate units of primary signals processing are connected with a digital computer machine. The system also comprises satellite navigation equipment, which with its outlets is connected to the digital computing machine. Additionally the system is equipped with a clock pulse oscillator and a coordinating time device. The outlet of the clock pulse generator is connected to the inlet of a coordinating time device and with an appropriate input of the digital computing machine. Due to introduction of a clock pulse oscillator and a coordinating time device into the system, processes of measurements collection and complex information processing are coordinated, and minimum dynamic distortions are present.

EFFECT: improved accuracy.

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Description

Technical field

The invention relates to the field of navigation devices and systems and can be used to determine with high accuracy the coordinates of the place and motion parameters of maneuverable aircraft.

State of the art

To determine the coordinates of the place and the parameters of the movement, strapdown inertial navigation systems (SINS) are widely used. They contain angular velocity sensors (gyroscopes) and apparent acceleration sensors (accelerometers), the output signals of which, with special mathematical processing, can determine the output navigation and flight data: geographical coordinates, components of the earth's velocity vector, heading angles, pitch and roll components of linear acceleration and the angular velocity of the aircraft in the axes associated with it (Babich OA Information processing in navigation systems. - M .: Mashinostroenie, 1991).

The disadvantage of SINS is the tendency to an unlimited increase in the errors of the output data over time. With the development of satellite navigation systems (GLONASS, GPS), to compensate for this shortcoming, it became possible to use on-board satellite navigation equipment (ASN). The ASN output navigation information (geographic coordinates and components of the earth velocity vector) can be used to compare it with the navigation data independently calculated in the SINS. The discrepancies of the coordinates and the velocity vector also provide the possibility of estimating (based on dynamic filtering algorithms) the errors of the course angles, pitch and roll, as well as uncompensated drifts of the angular velocity sensors.

When constructing algorithms for optimal joint processing of satellite navigation information and inertial data, one should take into account the peculiarities inherent in the processes of formation and transmission of information signals.

The output of the SINS navigation data is formed during the implementation of calculations in fast (with a frequency of 200 ... 1600 Hz) and slow (with a frequency of 50 ... 200 Hz) cycles of the built-in computer of the navigation system (Paul G. Savage. Strapdown System Computational Elements. - RTO-LS- 232 (2004) Pre-Prints, 2004). The signals of the angular velocity sensors (gyroscopes) and linear acceleration sensors (accelerometers) are fed to the input of the computational algorithm. In the general case, the frequency of interrogation of gyroscopes and accelerometers is different, but during the initial processing of signals it can be reduced to the frequency of calculations in a fast cycle. The update frequency of the output of the SINS navigation data coincides with the frequency of calculations in a slow cycle. The output of the SINS navigation data is relevant at individual points in the survey of sensors. At the same time, updating the data in the output digital lines is carried out with some delay relative to the moment of relevance associated with the need to perform mathematical processing.

The output data of the ASN is characterized by the presence of a special pulse signal indicating the moment of fixation of the primary radio navigation measurements - and, accordingly, the relevance of the output satellite navigation information generated during secondary processing in the ASN (Global Satellite Radio Navigation System GLONASS / Edited by V.N. Kharisov, A. I. Perova, V.A. Boldina. - M .: IPRZhR, 1998). Secondary processing is carried out in the ASN computer for some time, and this leads to a corresponding delay in updating data in the output digital lines.

Due to the delay in the output data, a dynamic error occurs, which adversely affects the process of joint processing of satellite navigation information with navigation data autonomously calculated in an inertial navigation system. They can be manifested in disruption of the algorithm for optimal joint information processing in the integrated inertial-satellite system of an aircraft during its maneuvering.

Known is the inertial-satellite navigation system (patent RU 2148796 C1, application No. 98120280/28 of 11/05/1998). Like the claimed invention, this system along with inertial navigation means contains satellite navigation equipment (satellite navigation system receiver). This system implements joint processing of satellite information and inertial data in order to increase accuracy. However, information processing in this system is carried out continuously in time, without taking into account time sampling and delays in digital processing and transmission of information over digital communication lines.

Known integrated navigation system (patent RU 2265190 C1, application No. 2004108184/28 of 03.23.2004). Like the claimed invention, this system for the purpose of integrating navigational aids contains a residual formation unit, optimal information processing units based on dynamic filtering algorithms (forecast unit and estimation unit). However, this system does not take measures to temporarily synchronize the mapped information flows. In practice, this will lead to the presence of dynamic errors in the composition of the residuals of navigation data during maneuvering of the aircraft, as a result of which the accuracy of the output information of the integrated system will be limited.

Known integrated inertial-satellite navigation system (patent RU 2277696 C2, application No. 2004111865/28 of 04/21/2004) and inertial-satellite navigation system with combined use of satellite data (patent RU 2334199 C1, application No. 2007110428/28 of 19.03. 2007). Like the claimed invention, these systems along with inertial navigation means contain satellite navigation equipment (multi-channel radio), a complex processing unit (information complexing unit). Systems implement comprehensive optimal information processing based on dynamic filtering algorithms. However, they also do not take measures to temporarily synchronize the mapped information flows.

Known integrated strapdown inertial-satellite navigation system on the "coarse" sensitive elements (patent RU 2380656 C0, application No. 2008150960/28 from 12.24.2008). This system, as well as the proposed one, contains satellite navigation equipment, a block of angular velocity sensors and linear acceleration sensors. Its computing platform contains blocks of quaternion calculations and recalculation of accelerations from the coordinate system connected to the navigation system, which are carried out in the fast cycle of the calculator of the proposed system, as well as a block for calculating the matrix of guiding cosines and orientation angles and a block for calculating linear and angular velocities of the navigation coordinate system, which are slow cycle calculator of the proposed system. It contains a master filter in which joint processing of inertial and satellite information is carried out. However, it also does not take measures to temporarily synchronize the mapped information flows. As already mentioned, the consequence of this is the limited accuracy of the output information of the complex system.

A known system for measuring the angular positions of an aircraft (patent RU 2244262, application No. 2002135344/28 of 12.27.2002). Like the claimed invention, this system contains angular velocity and linear acceleration sensors, as well as ASN (satellite navigation system). However, this patent uses synchronous reception of data from information systems. Therefore, its application for the case most typical in practice, when the frequencies of arrival of measurements and navigation data are different and may even be incoherent, seems problematic and will lead to limited accuracy of the output information of the complex system.

The closest analogue (prototype) to the claimed invention is an integrated navigation system (patent RU 2178147 C1, application No. 2000124858/28 from 03.10.2000). Like the claimed invention, this system along with inertial navigation means contains satellite navigation equipment (satellite navigation system). This system implements the function of generating residuals taking into account the time shift between the moment of relevance of satellite navigation information and the moment of updating information in a digital communication line. (A special extrapolation of satellite navigation information is provided by the introduction of appropriate amplifiers, adders, integrators, and delay lines.) This reduces the dynamic errors of the residuals, and, therefore, improves the accuracy of navigation information.

The disadvantage of this system in all the options considered in the patent is that the time discreteness is not taken into account when processing signals in SINS and issuing information from it. Thus, neglecting a time slice of 1/50 s when generating SINS in the slow calculation cycle produces output coordinate signals and a velocity vector for an aircraft making a bend with a roll of 60 ° at a speed of 200 m / s (with lateral acceleration of 17.3 m / s ² ) , will cause dynamic error in the formation of residuals: in coordinates - up to 4 m, in speed - up to 0.35 m / s. These values are comparable with the errors in satellite navigation in the normal mode of operation, and for the differential mode of ASN, they exceed two times or more.

In addition, due to the peculiarities of dispatching computational procedures in the ASN, the time delay between the moments of the relevance of navigation information and updating the output can be a variable. This fact will also lead to a decrease in the accuracy of this system.

Thus, the main disadvantage of the known inertial-satellite navigation systems is the insufficiently accurate time synchronization of the SINS output navigation data and satellite navigation information during the formation of residuals of coordinates and velocity vector. This leads to dynamic errors of residuals and, as a result, to problems in the integrated processing of information. Ultimately, to limiting the accuracy of an integrated navigation system. These restrictions become most noticeable when maneuvering an object.

The main objective of the invention is to improve the accuracy of the integrated inertial-satellite navigation system by organizing accurate time synchronization of navigation data streams.

Disclosure of invention

The embodiment of the invention will allow due to the organization of accurate time synchronization of the navigation data streams to increase the accuracy of the integrated inertial-satellite navigation system.

To obtain a technical result, the proposed system comprises: a block of angular velocity sensors, a block of linear acceleration sensors, a block of primary processing of angular velocity signals, a block of primary processing of linear acceleration signals, satellite navigation equipment, a clock generator, a coordinating temporary device, and a digital computer, which includes fast cycle calculation module, slow cycle calculation module, residual formation module, complex processing module.

The output of the clock generator is connected to the input of the coordinating temporary device and to the corresponding input of the digital computer (in the part of the module for generating residuals).

The coordinating temporary device is connected with its outputs to the corresponding inputs of the block of angular velocity sensors, the block of linear acceleration sensors, the block of primary processing of angular velocity signals, the block of primary processing of linear acceleration signals and a digital computer (in terms of the fast cycle calculator, the slow cycle calculator, the module formation of residuals, integrated processing module).

The output of the block of angular velocity sensors is connected to the corresponding input of the block of primary processing of angular velocity signals.

The output of the linear acceleration sensor unit is connected to the corresponding input of the primary linear acceleration signal processing unit.

The outputs of the primary processing unit of the angular velocity signals and the primary processing unit of the linear acceleration signals are connected to the corresponding inputs of the digital computer (in the part of the fast cycle computing module and the residual generation module).

The output of the fast cycle computing module is connected to the corresponding inputs of the slow cycle computing module and the residual generation module.

The output of the slow cycle computation module forms the flight and navigation data and is connected to the corresponding inputs of the integrated processing module and the residual formation module.

The output of the residual formation module is connected to the corresponding input of the integrated processing module.

The output of a digital computer (in terms of the integrated processing module) forms the output of high-precision flight and navigation data.

Brief Description of the Drawing

The drawing shows a block diagram of the proposed system.

The proposed system includes:

1 - clock generator (GTI);

2 - coordinating temporary device (HLC);

3 - digital computer (digital computer);

4 - satellite navigation equipment (ASN);

5 - module for the formation of residuals (MFN) of the computer;

6 - integrated processing module (MCO) of the computer;

7 - block of angular velocity sensors (BDUS);

8 - block primary processing of angular velocity signals (BODUS);

9 is a module for computing a fast cycle (MVBC) computer;

10 is a module for computing a slow cycle (MVMTS) computer;

11 is a block of linear acceleration sensors (BDLU);

12 is a block of primary processing of linear acceleration signals (BSS).

The information exchange between the inputs and outputs of the blocks is carried out along the communication lines shown in the drawing by directional lines (both solid and dashed). The dashed lines show the signals of the clock pulses. Solid lines - signal transmission lines on digital communication lines, including serial and parallel code transmission lines. The double lines show the directions of data transmission during processing in the digital computer of the system.

In the drawing, the following signal symbols are used:

f _GTI - clock system signal;

f _MC - a clock signal of a slow cycle of calculations in a digital computer;

f _BC - clock signal of a fast calculation cycle in a digital computer;

f _1s - clock signal of relevance of satellite navigation information;

{PNDVT} - high-precision flight and navigation data;

In ^C , L ^C , h ^C , v _ENU ^C - satellite navigation information: geodetic latitude, longitude and altitude, as well as the earth velocity vector in the east-north-vertical axes;

{PN} - parameters of residuals of navigation information;

f _ω is the clock signal of the interrogation of the angular velocity sensors;

ω is the vector of the measured angular velocity in the connected axes of the object;

q is the increment vector of the apparent angle in the associated axes of the object;

{PBC} - parameters of the fast calculation cycle in a digital computer;

{PNA} - flight and navigation data;

f _a - clock signal polling linear acceleration sensors;

a is the vector of the measured linear acceleration in the associated axes of the object;

Δv is the increment vector of the apparent speed in the associated axes of the object.

The implementation of the invention

In the block of angular velocity sensors 6, the angular velocity vector of the object is measured in projections onto the connected axes ω and the measurement signals are transmitted, for example, along a digital line in the form of a serial code according to GOST 18977-79.

In the block of linear acceleration sensors 10, it is possible to measure the linear acceleration vector of the object in projections onto the connected axes a and to issue measurement signals, for example, along a digital line in the form of a parallel code in accordance with GOST 18977-79.

In the blocks of the primary processing of angular velocity signals 8 and the primary processing of linear acceleration signals 12 at an ultrafast pace, the processing of measurement signals is carried out. It consists, for example, in integrating them to reduce the frequency of the fast cycle of calculations:

,

, где

,

where

T _BC - the duration of the calculation interval of the fast cycle of the computer;

N _ω and N _a are, respectively, the number of samples of measurements of the angular velocity and linear acceleration in the calculation interval of the fast cycle.

The output data of the blocks of the primary signal processing with some deterministic delay are relevant at the time of the clock pulse f _BC .

In the module for computing the fast cycle of digital computer 9, mathematical processing is carried out to determine the parameters of the fast cycle {PBC}, which are intermediate data of the strapdown inertial navigation algorithm. Processing may be carried out, for example, according to [Paul G. Savage. Strapdown System Computational Elements. - RTO-LS-232 (2004) Pre-Prints, 2004]. The composition of the parameters of the fast cycle in this case will include, in particular, the increment of the apparent speed and the vector of the apparent rotation of the object in the calculation interval within the cycle of the fast cycle. The output of the fast cycle calculation module with some deterministic delay is relevant at the time of the clock pulse f _BC .

In the computing module of the slow cycle of the digital computer 10, mathematical processing is carried out to determine the aeronautical navigation data {PND}, which are the output of the strapdown inertial navigation algorithm. Processing may be carried out, for example, according to [Paul G. Savage. Strapdown System Computational Elements. - RTO-LS-232 (2004) Pre-Prints, 2004]. The composition of the navigation data in this case will include, in particular, the geographical coordinates of the object, the vector of its earth speed and the flight angles of the aircraft. The output of the slow cycle computation module with some deterministic delay is relevant at the time of the clock pulse f _MC .

In the module for the formation of residuals 5, satellite navigation information is compared with inertial navigation data included in the {PND}: geodesic latitude B ^I , longitude L ^I and height h ^I and the earth velocity vector in the east-north-vertical axes v _ENU ^I.

To compare the navigation information, a single point in time is used, which corresponds to the leading edge of the pulse f _1c “second mark” ACH. Satellite navigation data (latitude B ^C , longitude L ^C , height h ^C , earth velocity vector v _ENU ^C ) transmitted with some deterministic delay, for example via a digital line in the form of a serial code according to GOST 18977-79, are relevant strictly at this point in time . At the same time, in order to bring inertial flight and navigation data into the MFN module, the corresponding data processing is performed:

1) using obsolete by pulses f _BC and fixed by pulses f _1s counter of pulses f _GTI , the obsolescence of the fast cycle parameters τ _{BC is} determined;

2) according to an algorithm identical to that performed in the MVMC module [Paul G. Savage. Strapdown System Computational Elements. - RTO-LS-232 (2004) Pre-Prints, 2004], an extraordinary calculation of inertial navigation data is performed using the current values of the fast cycle parameters {PBC};

3) upon receipt of the next (corresponding to the following _BC pulse f _1c sample) signals q, Δv they are scaled in proportion to the obsolescence of the fast cycle parameters:

,

,

,

,

then the scaled inertial measurement signals are used to refine the inertial navigation data according to the following steps 4) and 5);

4) according to the scaled data q ^* , Δv ^{*, the} parameters of the fast cycle are calculated at one step according to an algorithm identical to that performed in the module of the IECC [Paul G. Savage. Strapdown System Computational Elements. - RTO-LS-232 (2004) Pre-Prints, 2004];

5) according to the results of the calculation of the fast cycle parameters at one step, the inertial navigation data is updated according to an algorithm identical to that performed in the IECM module [Paul G. Savage. Strapdown System Computational Elements. - RTO-LS-232 (2004) Pre-Prints, 2004].

As a result of processing according to claims 1-5, the inertial navigation data is brought to the time of the relevance of satellite navigation information. This allows you to create residuals of inertial and satellite navigation data:

ΔB ^IP = B ^AND -B ^C ;

ΔL ^IP = L ^AND -L ^C ;

Δh ^IP = h ^AND -h ^C ;

These discrepancies are relevant at the time of the leading edge of the pulse f _{1s the} “second mark” of the ASN. Their dynamic errors are minimized.

In the integrated processing module 6, based on the dynamic filtering method, the errors of inertial flight and navigation data are estimated using well-known forecasting and correction algorithms (see, for example, patent RU 2265190 C1, application No. 2004108184/28 of 03.23.2004). Due to the minimal dynamic distortion of the residuals, in contrast to the known systems, the integrated signal processing in the claimed invention will provide higher accuracy characteristics.

In addition, in the integrated processing module 6, the correction of inertial aerobatic navigation data is performed by the value of the estimates relevant to the moments f _{1 s} for their errors. Thus, the high-accuracy flight-navigation data {PNDVT} of the system is formed.

Due to the slow dynamics of inertial flight and navigation data errors when compensating for them in the MCO module, it is permissible to use the estimates obtained at the previous step of the Kalman filtering algorithm with their linear extrapolation to moments f _MC .

To coordinate the operation of components in the system, several clock signals are used.

The clock generator 1 generates a clock signal of the system f _GTI , which serves as the basis for a single time scale. (This can be, for example, a pulse signal of a discrete analog type according to GOST 18977-79 with a frequency of 1 MHz.)

This signal is used in the coordinating temporary device 2 for forming by dividing the frequency of the control pulses f _ω , f _a , f _BC , f _MC .

The clock signal of the interrogation of the angular velocity sensors f _ω (for example, pulses according to GOST 18977-79 with a frequency f _GTI / 625 = 1600 Hz) serves to fix the next count of the measured angular velocity vector of the object in the block of angular velocity sensors, as well as to control the request for the next measurement from the block of primary processing of angular velocity signals.

The timing signal of the interrogation of linear acceleration sensors f _a (for example, pulses according to GOST 18977-79 with a frequency f _GTI / 125 = 8000 Hz) serves to fix in the sensor unit the angular velocity of the next count of the measured vector of linear acceleration of the object, as well as to control the request for the next measurement from the block of primary processing of linear acceleration signals.

A clock signal of a fast calculation cycle f _BC (for example, pulses in accordance with GOST 18977-79 with a frequency f _GTI / 2500 = 400 Hz) serves to fix the output values of the increment vector of the apparent angle q and the increment vector of the apparent in the blocks of the primary processing of the signals of the angular velocity and linear acceleration Δv, a, and also to control the request for these signals from a digital computer (for transmission to the fast cycle calculation module and the residual formation module).

The clock signal of the slow cycle of calculations f _MC (for example, pulses according to GOST 18977-79 with a frequency f _GTI / 10000 = 100 Hz) serves to fix the output parameters in the fast cycle calculation module, as well as to control their transmission to the slow cycle calculation module and module formation of residuals. The leading edge of the pulse determines the moments of relevance of navigation and navigation data {PND} and high-precision output data of the system {PNDVT}.

The “second mark” signal ACH f _{1c is} used in the MFN module to determine obsolescence of fast cycle parameters (relative to the time of the relevance of satellite navigation information), as well as in the MCO module to determine the obsolescence of estimates for errors {PNA} (relative to the time of the relevance of flight and navigation data) .

Thus, by introducing a clock generator and a coordinating time device into the system, it is possible to organize inertial measurement collection processes and process inertial and satellite navigation and flight information in which the accuracy of the integrated system output information is improved due to minimal dynamic distortion distortions.

Claims (1)

Integrated inertial-satellite navigation system containing a block of angular velocity sensors, a block of linear acceleration sensors, a block of primary processing of angular velocity signals, a block of primary processing of linear acceleration signals, satellite navigation equipment, a digital computer, which includes a fast cycle calculation module, a slow calculation module cycle, residual formation module, complex processing module, the output of the block of angular velocity sensors connected to the corresponding input the unit for processing angular velocity signals, the output of the linear acceleration sensor unit is connected to the corresponding input of the unit for processing linear acceleration signals, the outputs of the unit for processing angular velocity signals and the unit for primary processing of linear acceleration signals are connected to the corresponding inputs of a digital computer (in the part of the fast cycle and residual formation module), the output of the fast cycle calculation module is connected to the corresponding inputs of the calculation module nth slow cycle and residual formation module, the output of the slow cycle computing module forms flight and navigation data and is connected to the corresponding inputs of the residual formation module and the integrated processing module, the outputs of the satellite navigation equipment are connected to the corresponding inputs of the residual generation module, the output of the residual generation module is connected to the corresponding the input of the integrated processing module, the output of the digital computer (in the part of the integrated processing module) forms the flight high-precision navigation data, characterized in that it is additionally equipped with a clock generator and a coordinating temporary device, and the output of the clock generator is connected to the input of the coordinating temporary device and to the corresponding input of a digital computer (in the part of the module for generating residuals), coordinating the temporary device with its outputs connected to the corresponding inputs of the block of angular velocity sensors, the block of linear acceleration sensors, the primary processing unit and angular velocity signals, a block of primary processing of linear acceleration signals and a digital computer (in terms of a fast cycle calculation module, a slow cycle calculation module, a residual generation module, an integrated processing module), and the first output of satellite navigation equipment is additionally connected to the corresponding digital computing input machines (regarding the integrated processing module).