RU2756668C1 - Method for navigation and information support of an autonomous unmanned underwater vehicle that monitors an underwater production complex - Google Patents

Abstract

FIELD: underwater navigation.

SUBSTANCE: invention relates to means of underwater navigation and communication and can be used to determine the location and control of autonomous underwater vehicles (AUV) performing continuous (periodic) monitoring of the technical condition of underwater infrastructure facilities, for example, subsea production complexes (SPC) with a large number of heterogeneous inspected objects, located on a large area, including when performing missions under the ice. In the method for navigation and information support of an autonomous unmanned underwater vehicle, in which a network of reference beacons with known coordinates, equipped with high-frequency short-range and low-frequency long-range hydroacoustic transmitting and receiving means of information exchange with the AUV, is placed in the work area, and the beacons are connected with communication lines with remote control point. AUV is equipped with an on-board number system, low-frequency (LF) hydroacoustic reception devices and high-frequency (HF) hydroacoustic reception and transmission devices for information exchange with reference beacons. Reference beacons with equipment for LF and HF hydroacoustic communications are installed at each inspected MPC facility and synchronized with the AUV with a universal time system. Operating frequency of the LF equipment is selected from the condition of providing a range equal to the size of the MPC area, and the operating frequency of the HF equipment is selected from the condition of providing a data transmission rate sufficient for transmitting a video frame in real time. The proposed effect is achieved due to AUV equipped with software for measuring the propagation time of navigation signals in the LF and HF bands from the set beacons and software for calculating the value of the effective speed of these signals, minimizing the error in calculating the current coordinates according to the generated rangefinder data in the low frequency range, and providing the refinement of these current coordinates when the AUV is in the high frequency range, by filtering them according to the rangefinder data of the high frequency range.

EFFECT: minimizing the error in calculating the current coordinates according to the generated rangefinder data in the low frequency range, providing the refinement of current coordinates when the AUV is in the high frequency range.

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Description

The invention relates to a means of underwater navigation and communication can be used to determine the location and control of autonomous underwater vehicles (AUV) performing continuous (periodic) monitoring of the technical condition of underwater infrastructure facilities, for example, subsea production complexes (MPC) with a large number of heterogeneous inspected objects located over a large area, including when performing missions under the ice.

It is known (Matvienko Yu.V., Remezkov A.V. The concept of creating a robotic complex for inspection and monitoring of the technical condition of underwater production facilities // Gas Industry. Automation. - 2020, No. 2 (802), pp. 30–37), which is a feature AUVs used to monitor the technical state of MPC objects, including taking into account their possible use in ice conditions, is a wide range of their functional characteristics. The AUV should be equipped with appropriate on-board measuring equipment for use during long transitions throughout the entire MPC site (for example, sonar survey and bottom profiling, photo survey, tracking and planned-high-altitude control of extended objects such as pipelines, measurement of physical and chemical fields), and for local work at compact individual objects (planned high-altitude control, detailed photo and video inspection, mechanical work). When performing programmable controlled missions throughout the MPC site, the dimensions of which, taking into account the length of underwater pipelines for delivering production products to the shore, can be tens of kilometers, AUVs must have means of precise geographic referencing of the work performed and the results obtained throughout the work area. AUV with on-board equipment for performing local work on individual objects and in their vicinity (for example, on a detailed photo and video inspection of objects and their components, the use of contact measuring equipment for technological operations at objects), in addition, it must be provided with precision navigation and high-speed information exchange with a remote point in order to implement supervisory control.

The main navigation device of the AUV is the on-board navigation system (BANS) for reckoning the current position according to the data of the heading, speed and depth sensors. To improve the accuracy of dead reckoning, navigational aids are used. When integrating BANS and an external, for example, hydroacoustic navigation system (HANS), a significant increase in navigation accuracy is provided (Ageev M.D., Kasatkin B.A., Kiselev L.V., Molokov Yu.G, Nikiforov V.V., Rylov N.I. Automatic underwater vehicles. - L., Sudostroenie, 1981, 223 p.).

The known method of navigation and information support of the AUV (Ageev MD, Kiselev LV, Matvienko Y. V. and others. Autonomous underwater robots. - M., Science, 2005, 398 S.). In the known method of navigation and information support, based on the complex processing of BANS and HANS data, the AUV is equipped with a BANS, including heading, speed and depth sensors, a network of autonomous reference transponder beacons from the HANS is set up in the work area, the coordinates of which are known on board the vehicle, and emitting navigation signals upon request from the AUV. The AUV is equipped with means of receiving, emitting and processing navigation signals to calculate its geographic coordinates based on the measured distances from the beacons. The range of operating frequencies of the HANS, at which the dimensions of its equipment can be placed on the AUV without significantly affecting its dimensions and autonomy, is usually 10-15 kHz, which provides an operating range of 5-10 km, while the integral estimate of the accuracy of determining the coordinates reaches 5- 10m. The technology for solving the navigation problem includes reckoning the current coordinates according to the BANS data, radiation from the AUV with a set period of the request signal for the reference hydroacoustic beacons, and receiving their responses for calculating onboard the distances from the beacons by measured times and a fixed fixed speed of signal propagation, the integration of onboard and hydroacoustic navigation data, with the correction of the accumulating dead reckoning errors by determining the position of the object according to the measured distances from the beacons. AUV control is provided by integrating control commands into the structure of navigation signals using a special antenna, which is part of the HANS ship equipment.

The disadvantages of this method when used in monitoring tasks are:

- the need to use a support vessel for the performance of work;

- a limited area of operation of the AUV due to its binding to the coverage area of reference beacons, the range of which is determined by the selected frequency range of the hydroacoustic communication channel;

- a sharp increase in the size of hydroacoustic equipment placed on the AUV for emitting beacon request signals with an increase in the range of navigation systems, which is achieved by lowering the operating frequency range,

- and, accordingly, a sharp decrease in the bandwidth of the communication channel, with a decrease in the operating frequency range, which does not ensure the fulfillment of monitoring tasks,

-insufficient navigation accuracy when the AUV is operating directly at the inspected facility.

Thus, this method does not provide navigation and information support for the monitoring tasks formulated above and, moreover, is inapplicable in ice cover conditions.

Monitoring tasks require a simultaneous increase in the range of operation of hydroacoustic navigation and information support systems, which is achieved by lowering their operating frequencies, as well as an increase in the speed of information exchange, which is achieved by increasing the operating frequencies of these systems.

There is also known a method of navigation and information support of an autonomous unmanned underwater vehicle (RF Patent No. 2687844 Method of navigation and information support of an autonomous unmanned underwater vehicle of large autonomy, making an extended underwater passage., Publ. 16.05.2019, bull. No. 14), based on the application reference hydroacoustic beacons that implement information exchange with the AUV via a hydroacoustic communication channel in two ranges, low-frequency (LF) and high-frequency (HF).

In this known way:

- a rare network of hydroacoustic beacons is set up along the traffic route, which serve as reference points for navigation correction and information exchange of the AUV with a remote control point, while the beacons are equipped with low-frequency and high-frequency hydroacoustic communications and are connected with communication lines to the control center,

- the current position of the AUV is determined by the BANS data, the integration is carried out sporadically when the AUV enters the observation zone to the nearest reference beacon, the size of the observation zone is determined by the range of the beacon in the HF range, and the LF range is used to obtain rangefinder data that are used to get the AUV to the nearest lighthouse. The accumulated errors of the calculated coordinates are corrected by comparing them with the calculated coordinates according to the rangefinder data from the reference beacon in the HF range,

- the working range of the HF channel is established by the condition of ensuring the transmission of telemetric data and the reception of control commands when the AUV is in the observation area. At the same time, no restrictions are imposed on the time of information exchange.

In this method, the AUV is equipped with HF reception and emission means and LF reception means for information exchange with the reference beacon, in addition, the AUV is equipped with software for its on-board control system, which implements the AUV output to the reference beacon based on the reception and processing of data received from the reference beacon. beacon in the low frequency range. Receiving control commands on board the AUV transmitted from the reference beacon in the high-frequency range and transmitting telemetry data from the AUV board to the beacon in the high-frequency range.

Additionally, the values of the operating frequencies of the hydroacoustic information exchange in the low frequency range are chosen so that the range of their operation is at least twice the maximum reckoning error according to the data of the AUV onboard navigation system for the period between observations, and the values of the operating frequencies of the hydroacoustic information exchange in the high frequency range is selected from the condition of providing the channel capacity for transmitting a small amount of telemetry data generated between observations.

This method of navigation in its functional purpose, in its technical essence and the achieved technical result is closest to the claimed one.

The disadvantage of the known method, when applied to an AUV performing monitoring tasks over a large MPC site, is that outside the coverage area of high-frequency hydroacoustic communication means, the current location is determined according to the reckoning data of the BANS with a large error, the value of which is unacceptable when performing continuous work on the site (for example in case of detailed tracking and planning and altitude control of extended objects such as pipelines, the coordinate referencing error should not exceed a few meters, and the dead reckoning error without correction grows at least at a speed of several tens of meters per hour. M. D. Ageeva. Vladivostok: Dalnauka, 2000, 272s., P. 123) Other disadvantages of the known method are the lack of information support via the hydroacoustic communication channel when moving outside the observation zones, insufficient navigation accuracy when the AUV operates at the inspected object, is insufficient I the bandwidth of the HF hydroacoustic communication channel and the long transmission time of large amounts of information, for example, image frames, necessary for the supervisory control of the AUV when it performs technological operations at the facilities, in real time.

The objective of the present invention is to develop a method for providing navigation and information support for an AUV performing missions to perform a wide range of monitoring tasks on compact and extended MPC objects located on a vast area of the seabed, and providing a solution to navigation and information exchange problems with a control point, including in ice conditions.

The problem is solved by the fact that

in the method of navigation and information support of an autonomous unmanned underwater vehicle that monitors an underwater mining complex (MPC), in which a network of hydroacoustic beacons is placed on the MPC site at points with known coordinates, beacons are connected with communication lines to a remote control station and equipped with high-frequency short-range operations and low-frequency long-range hydroacoustic transmitting and receiving means of information exchange with the AUV, and the AUV is also equipped with HF hydroacoustic transmitting and receiving means and LF hydroacoustic receiving means for information exchange with hydroacoustic beacons, then the current position of the AUV is determined by the onboard number system, and the numbering errors are corrected by Based on the calculation of the coordinates of the AUV based on the rangefinder data from the beacons, control commands are received from a remote point on board the AUV by receiving and processing data transmitted from the sonar unit yak, transmit telemetry data to a remote control point from the AUV by receiving and processing data received by the beacon;

- reference beacons with equipment for LF and HF hydroacoustic communication are installed at each inspected object of the MPC and synchronized with the AUV with a universal time system;

- the operating frequency of the LF equipment is selected from the condition of providing a range equal to the size of the MPC area, and the operating frequency of the HF equipment is selected from the condition of ensuring a data transmission rate sufficient for transmitting a video frame in real time;

- AUV is equipped with software for measuring the propagation time of navigation signals in the LF and HF ranges from the set beacons and with software for calculating the value of the effective speed of these signals, which minimizes the error in calculating the current coordinates based on the generated rangefinder data in the LF range and providing the refinement of these current coordinates when finding AUVs in the HF coverage area, due to their filtering according to HF rangefinder data.

In this method, the control of the AUV, when it is at the MPC site, is performed by receiving and processing data transmitted from the control point through the equipment of the reference beacon in the low frequency range and providing two-way information exchange through the beacon equipment in the high-frequency range, when the AUV is in the vicinity of the inspected object ...

Comparative analysis of the proposed technical solution and the prototype shows that the first, in contrast to the prototype, has the following essential features:

Sign: ".. support beacons with equipment for LF and HF hydroacoustic communication are installed at each inspected MPC facility ..." - provides at the MPC site the formation of an extensive network of HANS beacons in the low frequency range and provides the possibility of high-speed information support during AUV operation at each facility.

Sign: ".. support beacons with equipment for LF and HF hydroacoustic communication ... synchronize .. with the AUV system ..." - provides the ability to measure the propagation time in an asynchronous mode, which makes it possible to use only receiving equipment on board the AUV in the LF range without bulky radiation equipment.

Sign: ".. the operating frequency of the LF equipment is selected from the condition of ensuring a range equal to the size of the MPC area" - ensures the reception of LF navigation signals on board the AUV from each installed beacon at each point of the MPC, while the reception of signals from three beacons already makes it possible to unambiguously determine the current position of the AUV throughout the MPC site, and reception from more beacons is used to improve accuracy.

Sign: "the operating frequency of the HF equipment is selected from the condition of ensuring a data transmission rate sufficient for transmitting a video frame in real time" - provides the possibility of supervisory control of the underwater vehicle when it performs technological operations at the inspected object and is used to additionally accurately determine the range of the AUV from the inspected object ...

Sign: "AUV is equipped with software for measuring the propagation time of navigation signals in the LF and HF ranges from the set beacons and with software for calculating the value of the effective speed of these signals, which minimizes the error in calculating the current coordinates from the generated rangefinder data in the LF range ..." - provides the implementation of navigation requirements for AUVs performing monitoring of the technical condition of MPC objects - high accuracy of navigation on the MPC site, since when calculating the ranges, the effective signal speed is not fixed, but is a calculation parameter based on redundant ranging data.

Sign: "... AUV is equipped with software that provides clarification of these current coordinates when the AUV is in the HF coverage area, by filtering them according to HF rangefinder data ..." HF range. HANS LCH determines the position of the AUV in the form of a circle, the center of which is the calculated estimate of the coordinates, and the radius is the error of their calculation. When combining these data with the distance from the beacon in the HF range, the position of the AUV is determined by the area of intersection of this circle with the ring, the radius of which is the range, and the width of the ring is the error in measuring the range. With the connection of BANS data when moving, for example, with a fixed course and speed, the distance traveled is reckoned. At the same time, the change in the current range in the HF range is also determined. The ratio of the change in range to the distance traveled determines the bearing to the AUV from the point where the beacon is located, due to this, the area of the AUV is established by the intersection of the mentioned circle and ring in the angular sector, determined by the values of the bearing and the error in its calculation. It is easy to show that if the error in the LF GANS is 1-3 m, the error in measuring the range in the HF range is 0.02 m, the reckoning error according to the data of the heading and speed sensors is 0.2 m in 10 seconds, then the AUV is in the operating area HF equipment determines its position with an error of less than 0.1 m.

EFFECT: provision of navigation and information support of AUV, which monitors an underwater mining complex, is achieved by placing a network of reference beacons operating in two frequency ranges at each inspected MPC object, algorithms for processing navigation signals that ensure navigation errors in the work on the MPC site. more than 1-3 m and an error in the vicinity of the inspected objects of less than 0.1 m, as well as the use of HF hydroacoustic communication equipment that provides the possibility of supervisory control of the AUV when performing work on the objects.

The set of essential features of the claimed invention has a causal relationship with the achieved technical result. Based on the foregoing, it can be concluded that the claimed technical solution is new and has an inventive step, since does not explicitly follow from the prior art and is suitable for industrial use.

The method is implemented as follows.

An AUV that monitors an underwater mining complex with an expanded set of on-board measuring equipment, including equipment for working throughout the MPC site and equipment for performing technological operations at the inspected facilities, can be deployed as part of an underwater station installed at the MPC site, including in ice conditions.

AUV, after receiving a task to perform monitoring work, moves around the MPC site and receives navigation signals in the low-frequency range from the installed beacons in the common time system with the beacons and determines the propagation time from each beacon. When receiving signals from three or more beacons, redundant data allows you to set the average effective speed (Matvienko Yu.V., Vaulin Yu.V., Kamorny A.V. Graduation of navigation aids for underwater robots // Underwater Research and Robotics. 2015, No. 1 ( 19), pp.16-23) propagation of navigation signals and with greater accuracy calculate the distance from the beacons, and then determine the current coordinates of the AUV. In addition, as part of the LF navigation signals, using well-known coding methods, if necessary, commands to control the progress of work from a remote (coastal) point are transmitted. When performing work on the MPC site, the operation of the measuring equipment becomes rigidly tied to time and geographic coordinates, which makes it possible to perform work on monitoring the state of extended and compact objects, measuring physical and chemical fields, sonar survey of the relief and profiling of the bottom structure, and other work on the entire MPC site ...

To perform complex technological operations directly at the inspected object and in its immediate vicinity, the AUV, being in the coverage area of HF equipment, uses two-way information exchange in the HF range. The algorithm for solving the navigation problem using low-frequency rangefinder data is supplemented by measurements of the current range of the AUV from this beacon in the high-frequency range, which improves the navigation accuracy at this object by filtering the coordinates obtained from the low-frequency range data. For example, if the operating frequency of the HF range is 500 kHz, then when the AUV is in the vicinity of a beacon with a radius of less than 10 m, the range measurement with a unit error is implemented in the HF range. precision navigation (with an integral navigation error of less than 0.1 m) at the inspected object.

The high frequency of HF equipment also makes it possible to significantly increase the throughput of this communication channel (for example, at a frequency of 500 kHz and a band of 100 kHz, the transmission rate over the hydroacoustic channel can be more than 100 kbit / s) and ensure the transmission of photo or video frames from the AUV to the point management in real time, providing supervisory control of the necessary technological operations.

Claims (4)

A method of navigation and information support for an autonomous unmanned underwater vehicle (AUV) monitoring an underwater mining complex (MPC), in which a network of hydroacoustic beacons is placed on the MPC site at points with known coordinates, beacons are connected with communication lines to a remote control station and equipped with high-frequency short-range and low-frequency long-range hydroacoustic transmitting and receiving means of information exchange with the AUV, and the AUV is also equipped with HF hydroacoustic transmitting and receiving means and LF hydroacoustic receiving means for information exchange with hydroacoustic beacons, then the current position of the AUV is determined by the onboard number system, and is corrected reckoning errors based on the calculation of the coordinates of the AUV based on the rangefinder data from the beacons, receive control commands from a remote point on board the AUV by receiving and processing data transmitted from the sonar unit yak, transmit telemetry data to a remote control point from the AUV by receiving and processing data received by the beacon, characterized in that the reference beacons with equipment for low-frequency (LF) and high-frequency (HF) communication are installed at each inspected object of the MPC and synchronized with a system of uniform time with the AUV; - the operating frequency of the LF equipment is selected from the condition of providing a range equal to the size of the MPC area, and the operating frequency of the HF equipment is selected from the condition of ensuring a data transmission rate sufficient for transmitting a video frame in real time; - AUV is equipped with software for measuring the propagation time of navigation signals in the LF and HF ranges from the set beacons and with software for calculating the value of the effective speed of these signals, which minimizes the error in calculating the current coordinates based on the generated rangefinder data in the LF range and providing the refinement of these current coordinates when finding AUVs in the HF coverage area, due to their filtering according to HF rangefinder data.