An underwater robot multi-device combined navigation system and method

Abstract

The invention belongs to a kind of marine equipment, and provides a multi-device combined navigation system and method for an underwater robot, comprising: a strapdown inertial navigation device, a global satellite positioning system, a Doppler log, a depth meter, a current meter, a propulsion motor, and an electronic chart. The Doppler log obtains the absolute speed information of the underwater robot to the bottom and the height information from the bottom in real time after the underwater robot is deployed into the water; the depth meter outputs the navigation depth information of the underwater robot in real time, and the current meter outputs the ocean current speed and direction in real time; the propulsion motor outputs the propulsion motor speed in real time, and the strapdown inertial navigation device receives the relevant information output by the global satellite positioning system, the Doppler log, the depth meter, the current meter, and the propulsion motor, and then passes through a combined navigation fusion algorithm and reads the map information of the electronic chart, and outputs the position information, attitude information and speed information of the underwater robot in real time to form accurate navigation and positioning information of the underwater robot.

Description

Technical Field

[0001] The present invention belongs to the field of marine equipment, relates to underwater robot navigation technology, and in particular to an underwater robot multi-device combined navigation system and method. Background Art

[0002] Due to the harsh environment beneath the ocean surface, human diving depth is affected by factors such as the external pressure of seawater and can only dive within a certain depth. The diving operation depth is limited. Underwater robots are increasingly becoming an important tool for ocean development such as marine resource exploration, marine life research, marine environment observation, underwater target search and rescue and salvage.

[0003] Navigation equipment is one of the basic equipment for underwater robots to obtain their own positioning information, realize path planning and navigation. Unlike robots used on land and in the air, traditional satellite navigation cannot be used in underwater robot equipment because radio waves attenuate rapidly when propagating in water.

[0004] At present, most underwater robots use inertial navigation devices, odometers, global satellite positioning systems, acoustic positioning systems and other equipment for navigation and positioning. The acoustic positioning system requires external ship tracking or a large number of acoustic positioning beacons in the sea area. The acoustic positioning operation distance is limited, which limits the flexibility of underwater robots and increases the security requirements of underwater robots. However, when there is no other navigation equipment to compensate, the positioning error of the inertial navigation device gradually accumulates and diverges as the underwater robot sails underwater. Therefore, the inertial navigation device of the underwater robot is generally used in conjunction with the odometer; the odometer has a certain The speed error output during normal bottoming in the water depth range is small, but as the underwater robot sails towards the deep sea, the odometer will not be able to bottom out and will switch to convection working mode. The odometer test accuracy drops sharply in convection working mode, which directly affects the combined navigation and positioning accuracy of the odometer and inertial navigation device. Currently, most underwater robots will float to the surface and calibrate through the global satellite positioning system to eliminate navigation errors caused by long-term underwater navigation. However, due to the need to frequently float and dive, the underwater robot's energy and effective operating time will be wasted, and the concealment of the underwater robot will be reduced.

[0005] Therefore, if underwater robots need to navigate autonomously underwater for a long time and need to reduce the loss of concealment, increased energy consumption and reduced operating time caused by surfacing to the surface, high-precision combined navigation technology has always been one of the main key technologies that underwater robots need to solve for navigating in deep waters.

[0006] CN 110044378A records an optical fiber strapdown inertial navigation high-precision positioning system and method for an underwater submersible, comprising a global positioning system module, a strapdown inertial navigation receiving module, a Doppler odometer, a terrain geomagnetic sensor, an information fusion filtering module, and a navigation solution module. The global positioning system module is used to determine the carrier speed, position and attitude information before the carrier enters the water; the strapdown inertial navigation receiving module is used to measure the carrier speed, position and attitude information after the carrier enters the water; the Doppler odometer is used to measure the carrier speed, and the terrain geomagnetic sensor is used to measure the position and attitude information of the carrier; the information fusion filtering module is used to fuse and filter correct the carrier speed, position and attitude information output by the strapdown inertial navigation receiving module and the carrier speed, position and attitude information output by the Doppler odometer and the terrain geomagnetic sensor; and the navigation solution module is used to solve the data output by the strapdown inertial navigation receiving module and the data after fusion and correction processing to obtain accurate navigation speed, position and attitude information.

[0007] CN 110068331A records an underwater navigation and positioning device and system, comprising: a hydrophone, a processor and a sound source generator; the sound source generator is pre-fixed at a designated position in the water area where the underwater device is located, and the sound source generator is used to send a modulated sound wave signal, and the modulated sound wave signal carries time information of sending the modulated sound wave signal; the hydrophone is arranged on the outer surface of the underwater device, and the hydrophone is used to detect the modulated sound wave signal sent by the sound source generator; the processor is electrically connected to the hydrophone, and the processor is used to determine the distance between the sound source generator and the hydrophone according to the time information in the modulated sound wave signal received by the hydrophone, and determine the underwater position of the underwater device according to the position information of the sound source generator and the distance between the sound source generator and the hydrophone.

[0008] CN 105787489A records a matching navigation algorithm based on underwater topographic images. The matching navigation algorithm based on underwater topographic images is adopted to convert both a real-time image and a reference image to be matched with the real-time image into circular templates, and the invariant moment features of the two circular templates are extracted as matching content; the Euclidean distance of the invariant moment feature vectors between the real-time image and the reference image is used as a similarity measure; the position of the reference image corresponding to the minimum Euclidean distance is the matching position of the real-time image; a particle swarm optimization algorithm is adopted to replace a traversal search method; a multi-swarm idea is used to improve the particle swarm optimization algorithm; after searching for the matching position of the real-time image, a maximum cross-correlation method is used to determine the heading angle.

[0009] The article "Conversion of GPS Coordinate System and Its Application in Attitude Solution" published in the October 2008 issue of the "Command, Control and Simulation" journal derived the conversion relationship between the navigation coordinate system and the carrier coordinate system based on the Euler angle rotation, derived the corresponding conversion matrix, and on this basis derived and explained the method of determining the carrier attitude. Summary of the invention

[0010] The technical problem to be solved by the present invention is to provide an underwater robot multi-device combined navigation system and method. Aiming at the problems existing in the current common underwater navigation technology, a strapdown inertial navigation device, a global satellite positioning system, a Doppler log, a depth gauge, a current meter, a propulsion motor, an electronic chart, a navigation computer and other multiple devices are used in combination to suppress the problem of low combined navigation accuracy of the strapdown inertial navigation device and the log caused by low test accuracy of the log convection mode when the underwater robot is sailing in the deep sea, thereby significantly improving the navigation accuracy of the underwater robot sailing in deep water areas.

[0011] In order to solve the above technical problems, the technical solution adopted by the present invention is: an underwater robot multi-device combined navigation system, which includes a strapdown inertial navigation device, characterized in that the strapdown inertial navigation device is connected to a global satellite positioning system, a Doppler log, a depth meter, a current meter, and a propulsion motor;

[0012] The global satellite positioning system is used to obtain the absolute position and speed of the underwater robot in real time before the underwater robot dives on the shore or the deployment vessel, and send it to the strapdown inertial navigation device for coarse and fine alignment, obtain the initial longitude and latitude information of the underwater robot and solve the attitude matrix, or obtain the absolute position and speed of the underwater robot after surfacing to eliminate the long-term navigation error of the inertial navigation device;

[0013] The Doppler log is used to obtain the underwater robot's absolute speed information and height information from the bottom in real time after the underwater robot is deployed in the water. The Doppler log and the strapdown inertial navigation device form a speed damping feedback mechanism for the underwater robot.

[0014] The depth meter is used to collect the underwater robot's navigation depth information in real time and send it to the strapdown inertial navigation device. The depth meter and the strapdown inertial navigation device form a height direction damping feedback mechanism for the underwater robot.

[0015] The current meter is used to collect the speed and direction of the underwater current of the underwater robot under the water surface, and send it to the navigation strapdown inertial navigation device to correct the speed error corresponding to the propulsion motor speed in still water;

[0016] The propulsion motor outputs torque to drive the underwater robot to navigate, and sends the propulsion motor speed to the strapdown inertial navigation device. The corresponding relationship between the speed and the underwater robot's navigation speed can be obtained based on theory and the actual underwater navigation experience of the underwater robot. When the Doppler log and the strapdown inertial navigation device are used for combined navigation, the speed information output by the Doppler log and the strapdown inertial navigation device during combined navigation is used as a benchmark, and the speed scale factor of the underwater robot's navigation speed inferred by the propulsion motor and the current meter can be calculated online, which can further optimize and improve the model accuracy formed by the propulsion motor speed and the current meter.

[0017] The strapdown inertial navigation device comprises a gyroscope and an accelerometer. The gyroscope is used to measure the angular velocity rate of the underwater robot, and the accelerometer is used to measure the speed information of the underwater robot.

[0018] The strapdown inertial navigation device has an electronic nautical chart in front of it, and the chart information such as the water depth, route obstacles and the like of the current position of the underwater robot can be queried according to the longitude and latitude information to verify whether the combined navigation calculation of the strapdown inertial navigation device is normal.

[0019] A navigation method using the above system, the above strapdown inertial navigation device has a built-in correspondence between the rotation speed of the propulsion motor and the still water uniform navigation speed of the underwater robot. When the underwater robot is navigating underwater, the strapdown inertial navigation device can calculate the navigation speed of the underwater robot on the X and Y axes based on the rotation speed of the propulsion motor and the current speed and current direction information output by the current meter, and can combine the Doppler odometer data.

[0020] When the underwater robot is sailing in shallow water and the Doppler log works on the bottom, the strapdown inertial navigation device is combined with the Doppler log and the depth gauge for navigation; when the underwater robot is sailing in deep water and the Doppler log cannot work effectively on the bottom, the strapdown inertial navigation device is combined with the propulsion motor, the current meter and the depth gauge for navigation. Since the Doppler log has a low bottom penetration depth, as the depth of the underwater robot's navigation water deepens, once the maximum bottom penetration depth of the Doppler log is exceeded, the Doppler log will work in the convection mode. The test accuracy in the convection mode drops sharply, resulting in a sharp drop in the combined navigation accuracy of the Doppler log and the strapdown inertial navigation device. At this time, the strapdown inertial navigation device will form accurate combined navigation positioning information based on the underwater robot's position information, attitude information and speed information calculated by its own pure inertial navigation, combined with the received propulsion motor speed information, the current speed and direction output by the current meter for comprehensive comparison, and after Kalman filtering.

[0021] The specific steps of the above navigation system are:

[0022] Step S1: The underwater robot control device controls the strapdown inertial navigation device to power on, and starts working after passing the self-check.

[0023] Step S2: The strapdown inertial navigation device performs initial alignment according to the latitude, longitude, speed and other information output by the global satellite positioning system, completes the attitude, position and speed calculation of the strapdown inertial navigation device itself, and outputs navigation information to the underwater robot navigation control center.

[0024] Step S3: After the strapdown inertial navigation device receives the output information of the Doppler log, the Doppler log works towards the bottom when sailing in shallow waters, and the strapdown inertial navigation device, the Doppler log, and the depth gauge are combined for navigation. At the same time, the error of the combined speed output by the propulsion motor and the current meter is calibrated online, and the combined speed scale factor of the propulsion motor and the current meter output is calculated.

[0025] Step S4: When the underwater robot sails to a deep water area exceeding the bottom depth of the Doppler log, the strapdown inertial navigation device, the propulsion motor, the current meter and the depth meter are combined for navigation.

[0026] Step S5: before the combined navigation is output, the electronic chart built into the strapdown inertial navigation device is called to verify the chart information such as the depth, route obstacles, etc. at the current longitude and latitude of the underwater robot.

[0027] Step S6: After the verification is passed, the strapdown inertial navigation device outputs the navigation information to the underwater robot navigation control center. When the underwater robot navigates to the set calibration point, the underwater robot floats to the surface for calibration.

[0028] Step S7: When the underwater robot autonomously navigates to the end of the route or the operation is completed, the underwater robot floats up and waits for recovery, completing the combined navigation.

[0029] When the underwater robot is navigating underwater, the strapdown inertial navigation device can calculate the navigation speed of the underwater robot in the X and Y axis carrier coordinate system according to the combined Doppler log data. The underwater robot navigation speed V is synchronously determined based on the propulsion motor speed and the current speed and current direction information received from the current meter. tz Calculate and use For speed V tz The speed scaling factor is calculated online.

[0030] The specific calculation process of the above step S3 is:

[0031] The transformation matrix between the carrier coordinate system b and the navigation coordinate system n is:

[0032]

[0033] Assume that the underwater robot encounters a current with a velocity of Vc and a direction of ψ in the geographic coordinate system during navigation. c , then the component of the flow velocity Vc in the carrier coordinate system is

[0034] V xc =V c cos(ψ c -φ)

[0035] V yc =V c sin(ψ c -φ)

[0036] is the speed of the strapdown inertial navigation unit / speed log in the navigation coordinate system after navigation, is the transformation matrix from the navigation coordinate system to the carrier coordinate system. Therefore, it can be concluded that k is the scale factor error equation:

[0037]

[0038] Compared with the currently common underwater robot navigation system, the beneficial effects of the present invention are:

[0039] 1) The application prospects are broad. The underwater robot multi-device combined navigation system of the present invention provides important engineering application technical support in most marine application fields, such as underwater exploration and search, underwater deep-depth long-distance scientific research, marine geological surveys and deep-sea biological research, because the underwater robot's own high-precision navigation is the basis and prerequisite for the underwater robot's own operation and navigation.

[0040] 2) To solve the problem of poor navigation accuracy at great depths, the present invention uses a Doppler log to measure speed with high accuracy in shallow waters, but in order to solve the problem of low test accuracy during convection of the Doppler log, the propulsion motor speed corresponds to a basically constant speed, and the current speed and direction output by the current meter are comprehensively calculated, and accurate combined navigation positioning information is formed after Kalman filtering. When the calibration finds a route deviation, the electronic chart software embedded in the inertial navigation device can further verify the correctness of the navigation output, thereby improving the accuracy of the combined navigation system.

[0041] 3) Reduce energy consumption and operation time. The present invention uses the propulsion motor speed of the underwater robot to be basically constant when it is sailing in the deep sea, and the current speed output by the current meter to form an accurate combined navigation accuracy after Kalman filtering. It can reduce the number of times the underwater robot floats and calibrates, increase its concealment, and reduce the energy consumption and effective operation time caused by frequent surfacing and diving. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0043] Figure 1 It is a composition diagram of the multi-device combined navigation system of the present invention;

[0044] Figure 2This is a schematic diagram of the multi-device combined navigation principle in the present invention;

[0045] Figure 3 This is a flowchart of the multi-device combined navigation control solution in the present invention;

[0046] Figure 4 This is a connection diagram of the strapdown inertial navigation unit.

[0047] In the figure: strapdown inertial navigation unit 1, global satellite positioning system 2, Doppler log 3, depth gauge 4, current meter 5, propulsion motor 6, electronic nautical chart 7. DETAILED DESCRIPTION

[0048] like Figure 1 In the invention, a multi-device combined navigation system of an underwater robot comprises a strapdown inertial navigation device 1, wherein the strapdown inertial navigation device 1 is connected to a global satellite positioning system 2, a Doppler log 3, a depth gauge 4, a current meter 5, and a propulsion motor 6;

[0049] The global satellite positioning system 2 is used to obtain the absolute position and speed of the underwater robot in real time before the underwater robot dives on the shore or the deployment vessel, and send it to the strapdown inertial navigation device 1 for coarse alignment and fine alignment, to obtain the initial longitude and latitude information of the underwater robot and solve the attitude matrix, or to obtain the absolute position and speed of the underwater robot after surfacing to eliminate the long-term navigation error of the inertial navigation device;

[0050] The Doppler log 3 is used to obtain the absolute speed information and the height information of the underwater robot from the bottom in real time after the underwater robot is deployed into the water. The Doppler log 3 and the strapdown inertial navigation device 1 form a speed damping feedback mechanism of the underwater robot.

[0051] The depth meter 4 is used to collect the navigation depth information of the underwater robot in real time and send it to the strapdown inertial navigation device 1. The depth meter 4 and the strapdown inertial navigation device 1 form a height direction damping feedback mechanism of the underwater robot; the current meter 5 is used to collect the speed and direction of the sea current of the underwater robot under the water surface and send it to the navigation strapdown inertial navigation device 1 to correct the speed error corresponding to the propulsion motor speed in still water;

[0052] The propulsion motor 6 outputs a torque to drive the underwater robot to navigate, and sends the rotation speed of the propulsion motor 7 to the strapdown inertial navigation device 1. The corresponding relationship between the rotation speed and the navigation speed of the underwater robot can be obtained based on theory and the actual underwater navigation experience of the underwater robot. When the Doppler log 3 and the strapdown inertial navigation device 1 are combined for navigation, the speed information output by the Doppler log 3 and the strapdown inertial navigation device 1 during the combined navigation is used as a reference, and the speed scale factor of the underwater robot navigation speed inferred by the propulsion motor 6 plus the current meter 5 can be calculated online, which can further optimize and improve the model accuracy formed by the rotation speed of the propulsion motor 6 and the current meter 5.

[0053] The circuit structure of the strapdown inertial navigation device 1 adopts a general architecture, and its inertial sensor adopts the CS-IMU-10 inertial measurement unit of China Satellite Measurement & Control Corporation, which integrates X, Y, and Z three-axis gyroscopes and accelerometers. The computer board of the strapdown inertial navigation device adopts Shenzhen Shengbo's SCM9032 system core module + SEM / CSD CAN bus interface module, based on Intel N455 processor, CAN communication interface, serial port and network port data communication interface, and can have a built-in operating system.

[0054] The global satellite positioning system 2 is a commercially available product, such as the BS-7953N GPS receiver from Shenzhen Beitian Communication.

[0055] The Doppler speed meter 3 is a commercially available product, such as the DVL500khz speed meter from Nortek.

[0056] The depth gauge 4 is a commercially available product, such as the SBE 50 digital pressure sensor from Seabird.

[0057] The above-mentioned current meter 5 is a commercially available product, such as the OS-38 phased array ocean survey ADCP produced by TRDI.

[0058] The above-mentioned propulsion motor 6 is a commercially available product, such as the underwater 500-meter motor of Jinan Yuli Direct Drive Motor Co., Ltd.

[0059] like Figure 4 In the embodiment, the strapdown inertial navigation device 1 comprises a gyroscope and an accelerometer. The gyroscope is used to measure the angular velocity rate of the underwater robot, and the accelerometer is used to measure the speed information of the underwater robot.

[0060] like Figure 1 In the above-mentioned strapdown inertial navigation device 1, there is an electronic nautical chart 7 in front of it, and the nautical chart information such as the water depth, route obstacles and the like of the current position of the underwater robot can be queried according to the latitude and longitude information to verify whether the combined navigation calculation of the strapdown inertial navigation device 1 is normal.

[0061] like Figure 3 , 4As shown in the figure, a navigation method using the above system is shown, the strapdown inertial navigation device 1 has a corresponding relationship between the rotation speed of the propulsion motor 6 and the still water uniform navigation speed of the underwater robot. When the underwater robot is navigating underwater, the strapdown inertial navigation device 1 can calculate the navigation speed of the underwater robot on the X and Y axes according to the rotation speed of the propulsion motor 6 and the current speed and current direction information output by the current meter 5, and can combine the data of the Doppler odometer 3.

[0062] When the underwater robot is navigating in shallow water and the Doppler log works on the bottom, the strapdown inertial navigation device 1 is combined with the Doppler log and the depth gauge 4 for navigation; when the underwater robot is navigating in deep water and the Doppler log cannot work effectively on the bottom, the strapdown inertial navigation device 1 is combined with the propulsion motor 6 and the current meter 5 and the depth gauge 4 for navigation. Since the bottoming depth of the Doppler log 3 is relatively low, as the depth of the underwater robot's navigation water area deepens, once the maximum bottoming depth of the Doppler log 3 is exceeded, the Doppler log 3 will work in the convection mode, and the test accuracy in the convection mode drops sharply, thereby causing the combined navigation accuracy of the Doppler log 3 and the strapdown inertial navigation device 1 to drop sharply. At this time, the strapdown inertial navigation device 1 will form accurate combined navigation positioning information after Kalman filtering based on the underwater robot position information, attitude information and speed information calculated by its own pure inertial navigation, combined with the received propulsion motor speed information, the current speed and direction output by the current meter.

[0063] The specific steps of the above navigation system are:

[0064] Step S1: The underwater robot control device controls the strapdown inertial navigation device 1 to power on, and starts working after passing the self-check.

[0065] Step S2: The strapdown inertial navigation device 1 performs initial alignment according to the latitude, longitude, speed and other information output by the global satellite positioning system 2, completes the posture, position and speed calculation of the strapdown inertial navigation device 1 itself, and outputs navigation information to the underwater robot navigation control center.

[0066] Step S3: After the strapdown inertial navigation device 1 receives the output information of the Doppler log 3, the Doppler log 3 works toward the bottom when sailing in shallow waters, and the strapdown inertial navigation device 1, the Doppler log 3, and the depth gauge 4 perform combined navigation, and at the same time, the error of the combined speed output by the propulsion motor 6 plus the current meter 5 is calibrated online, and the scale factor of the combined speed output by the propulsion motor 6 plus the current meter 5 is calculated.

[0067] Step S4: When the underwater robot sails to a deep water area exceeding the bottom depth of the Doppler log 3, the strapdown inertial navigation device 1 and the propulsion motor 6 plus the current meter 5 and the depth meter 4 are combined for navigation.

[0068] Step S5: before the combined navigation is output, the electronic nautical chart 7 built into the strapdown inertial navigation device 1 is called to verify the chart information such as the depth, route obstacles, etc. at the current longitude and latitude of the underwater robot.

[0069] Step S6: After the verification is passed, the strapdown inertial navigation device 1 outputs the navigation information to the underwater robot navigation control center. When the underwater robot navigates to the set calibration point, the underwater robot floats to the surface for calibration.

[0070] Step S7: When the underwater robot autonomously navigates to the end of the route or the operation is completed, the underwater robot floats up and waits for recovery, completing the combined navigation.

[0071] When the underwater robot is navigating underwater, the strapdown inertial navigation device 1 can calculate the navigation speed of the underwater robot on the X and Y axes according to the data of the combined Doppler log 3. The underwater robot navigation speed V is synchronously determined based on the rotation speed of the propulsion motor 6 and the current speed and current direction information received from the current meter 5. tz Calculate and use For speed V tz The speed scaling factor is calculated online.

[0072] The specific calculation process of the above step S3 is:

[0073] The transformation matrix between the carrier coordinate system b and the navigation coordinate system n is:

[0074]

[0075] Assume that the underwater robot encounters a current with a velocity of Vc and a direction of ψ in the geographic coordinate system during navigation. c , then the component of the flow velocity Vc in the carrier coordinate system is

[0076] V xc =V c cos(ψ c -φ)

[0077] V yc =V c sin(ψ c -φ)

[0078] is the speed of the strapdown inertial navigation unit / speed log in the navigation coordinate system after navigation, is the transformation matrix from the navigation coordinate system to the carrier coordinate system. Therefore, it can be concluded that k is the scale factor error equation:

[0079]

[0080] After obtaining the scale factor of the propulsion motor speed and the current speed measured by the current meter, the problem of a sharp drop in the combined navigation accuracy of the Doppler log 3 and the strapdown inertial navigation device 1 due to a sharp drop in the test accuracy of the Doppler log in the convection mode during deep water navigation can be avoided.

Claims

1. A multi-device integrated navigation system for an underwater robot, comprising a strapdown inertial navigation device (1), It is characterized in that The strapdown inertial navigation device (1) is connected to a global satellite positioning system (2), a Doppler log (3), a depth gauge (4), a current meter (5), and a propulsion motor (6); The global satellite positioning system (2) is used to obtain the absolute position information and speed information of the underwater robot in real time before the underwater robot dives or after it surfaces, and send the information to the strapdown inertial navigation device (1); The Doppler speed meter (3) is used to obtain the absolute speed information and the height information of the underwater robot from the bottom of the water in real time after the underwater robot is put into the water, and send the information to the strapdown inertial navigation device (1); The depth meter (4) is used to collect the navigation depth information of the underwater robot in real time and send it to the strapdown inertial navigation device (1); The current meter (5) is used to collect the speed and direction of the current under the water surface of the underwater robot and send it to the navigation strapdown inertial navigation device (1); The propulsion motor (6) outputs torque to propel the underwater robot to navigate, and transmits the rotation speed of the propulsion motor (6) to the strapdown inertial navigation device (1); The strapdown inertial navigation device (1) is equipped with an electronic nautical chart (7), which can query the water depth and route obstacle information of the underwater robot's current position according to the longitude and latitude information, so as to verify whether the combined navigation calculation of the strapdown inertial navigation device (1) is normal; When the underwater robot is navigating in shallow water and the Doppler log works toward the bottom, the strapdown inertial navigation device (1) is combined with the Doppler log and the depth gauge (4) for navigation; when the underwater robot is navigating in deep water and the Doppler log cannot effectively work toward the bottom, the strapdown inertial navigation device (1) is combined with the propulsion motor (6) and the current meter (5) and the depth gauge (4) for navigation, and the error of the combined speed output by the propulsion motor (6) and the current meter (5) is calibrated online at the same time.

2. The underwater robot multi-device integrated navigation system according to claim 1, Its characteristics are: The strapdown inertial navigation device (1) comprises a gyroscope and an accelerometer, wherein the gyroscope is used to measure the angular velocity rate of the underwater robot, and the accelerometer is used to measure the speed information of the underwater robot.

3. A navigation method using the system of claim 1, It is characterized in that The specific steps of the navigation system are: Step S1: The underwater robot control device controls the strapdown inertial navigation device (1) to power on and start working after passing the self-check; Step S2: the strapdown inertial navigation device (1) performs initial alignment according to the latitude, longitude and speed information output by the global satellite positioning system (2), completes the posture, position and speed calculation of the strapdown inertial navigation device (1) itself and outputs navigation information to the underwater robot navigation control center; Step S3: After the strapdown inertial navigation device (1) receives the output information of the Doppler log (3), the Doppler log (3) works toward the bottom when sailing in shallow waters, and the strapdown inertial navigation device (1) performs combined navigation with the Doppler log (3) and the depth gauge (4), and at the same time, performs online error calibration on the combined speed output by the propulsion motor (6) and the current meter (5); Step S4: When the underwater robot sails to a deep water area exceeding the bottom depth of the Doppler log (3), the strapdown inertial navigation device (1) and the propulsion motor (6) plus the current meter (5) and the depth meter (4) are combined for navigation; Step S5: before the combined navigation is output, the electronic nautical chart (7) built into the strapdown inertial navigation device (1) is called to verify the water depth and route obstacle information of the current position of the underwater robot at the current longitude and latitude; Step S6: After the verification is passed, the strapdown inertial navigation device (1) outputs the navigation information to the underwater robot navigation control center. When the underwater robot reaches the set calibration point, it floats to the surface for calibration. Step S7: When the underwater robot autonomously navigates to the end of the route or the operation is completed, the underwater robot floats up and waits for recovery, completing the combined navigation.

Images