Land north-seeking method and device based on single-axis high-precision gyroscope

Abstract

The application provides a land north-seeking method and device based on a single-axis high-precision gyroscope. When a ground mobile carrier is stationary at a first position, the axis of the single-axis high-precision gyroscope is perpendicular to the vertical axis of the carrier coordinate system, and the north-seeking state is entered. According to the output of the single-axis high-precision gyroscope and the output of a double-axis accelerometer, two first possible azimuth angles are obtained by using an attitude determination algorithm based on incomplete double-vector observation. The azimuth angle of the current position is determined by comparing the two first possible azimuth angles with the azimuth obtained by a navigation system or by using a two-position method of the ground mobile carrier. The application can achieve or approach the north-seeking effect of a three-axis high-precision gyroscope for the ground mobile carrier, has high north-seeking precision, and greatly reduces the cost.

Description

Technical Field

[0001] This invention relates to a land-based north-finding method and device based on a single-axis high-precision gyroscope, belonging to the field of inertial navigation technology. Background Technology

[0002] North-finding technology is used to determine the orientation of a vehicle's pointing axis relative to true north. Inertial navigation system-based north-finding essentially obtains its orientation by sensing the Earth's rotational angular velocity using a gyroscope. The Earth's rotational angular velocity is approximately 15° / h; for effective north-finding, the gyroscope must be able to detect this rate. Optical gyroscopes, including laser gyroscopes and fiber optic gyroscopes, meet this accuracy requirement and are commonly used.

[0003] Currently, north-finding methods based on inertial navigation systems primarily employ initial alignment using an inertial measurement unit (IMU). Initial alignment provides the inertial navigation system with its initial attitude. An IMU typically consists of a three-axis accelerometer and a three-axis gyroscope. Early initial alignment methods used analytical alignment, employing a dual-vector attitude determination method based on the gravitational acceleration sensed by the three-axis accelerometer and the Earth's rotation sensed by the three-axis gyroscope. This method yields the carrier's attitude (including north and horizontal angles) relative to the Earth. Today, the commonly used initial alignment method in engineering is the inertial frame alignment method. This method was first proposed by the French company IxSea in 2000. Their Octans product can complete alignment within 5 minutes on any swaying base. In China, Qin Yongyuan et al. first applied it to coarse alignment of ships in moored conditions. Initial alignment requires the use of a high-precision three-axis gyroscope, primarily an optical gyroscope. Due to its high cost, it is mainly used in military applications and is difficult to promote in the civilian sector.

[0004] The above-mentioned issues should be considered and resolved in the land-based north-finding process based on single-axis high-precision gyroscopes. Summary of the Invention

[0005] The purpose of this invention is to provide a land-based north-finding method and device based on a single-axis high-precision gyroscope, which solves the problem in the prior art that while ensuring high north-finding accuracy, the cost needs to be reduced.

[0006] The technical solution of this invention is:

[0007] A land-based north-finding method based on a single-axis high-precision gyroscope includes the following steps:

[0008] S1. When the ground-based mobile carrier is stationary at the first position, the axis of the single-axis high-precision gyroscope is perpendicular to the vertical axis of the carrier's coordinate system, and it enters the north-seeking state. Based on the output of the single-axis high-precision gyroscope and the output of the dual-axis accelerometer, the attitude determination algorithm based on incomplete dual-vector observation is used to obtain two first possible azimuth angles.

[0009] S2. Determine the azimuth of the current position by comparing the two first possible azimuth angles with the azimuth obtained by the navigation system, or by using the two-position method of the ground mobile carrier.

[0010] Furthermore, in step S1, the angle between the axis of the single-axis high-precision gyroscope along the x-axis or y-axis of the carrier coordinate system, or the angle between the axis of the single-axis high-precision gyroscope and the y-axis of the carrier coordinate system, is arbitrary. .

[0011] Further, in step S1, an attitude determination algorithm based on incomplete two-vector observations is used to obtain two first possible azimuth angles, specifically,

[0012] S11. The axis of the single-axis high-precision gyroscope is along the x-axis direction of the carrier coordinate system. Let the output of the hypothetical y-axis and z-axis optical gyroscope in the first static position be... and The hypothetical z-axis accelerometer output in the first stationary position is denoted as... The following equation is satisfied:

[0013] (1)

[0014] in, These are the x-axis accelerometer outputs and y-axis accelerometer outputs, respectively, and have already been normalized. The output is from a single-axis high-precision gyroscope and has already been normalized. Let be the angle between the gravity vector and the Earth's rotation vector, satisfying ,in, This is the local latitude value;

[0015] S12. Given the z-axis orientation, calculate the z-axis accelerometer output using equation (a) in (1);

[0016] S13, after obtaining the z-axis accelerometer output In this case, by solving equations (b) and (c) in equation (1), the output of the y-axis optical gyroscope can be obtained. and z-axis optical gyroscope output Two possible solutions;

[0017] S14. Two first possible azimuth angles are calculated using a three-axis attitude determination algorithm, namely the TRIAD algorithm or an optimized attitude determination algorithm.

[0018] Further, in step S1, an attitude determination algorithm based on incomplete two-vector observations is used to obtain two first possible azimuth angles, specifically,

[0019] Given the orientation of the z-axis accelerometer, and based on the fact that the magnitude of the triaxial accelerometer under static conditions is the magnitude of gravitational acceleration, the output of the z-axis accelerometer can be determined.

[0020] The roll and pitch angles of the ground mobile vehicle are determined based on the output of the triaxial accelerometer. The azimuth angle of the ground mobile vehicle is used as an undetermined coefficient, and the Earth's rotation vector is projected onto the vehicle coordinate system.

[0021] Based on the output of a single-axis high-precision gyroscope, two first possible azimuth angles of the ground mobile carrier are determined.

[0022] Further, in step S1, an attitude determination algorithm based on incomplete two-vector observations is used to obtain two first possible azimuth angles, specifically,

[0023] S101, the ground-based mobile carrier remains stationary at the first position for a set time, and the angle between the axis of the single-axis high-precision gyroscope and the y-axis of the carrier coordinate system is... The output of the single-axis high-precision gyroscope at the first position is denoted as... The outputs of the x-axis accelerometer and y-axis accelerometer at the first position are respectively denoted as... and Given the axial orientation of the z-axis accelerometer, and based on the fact that the magnitude of the triaxial accelerometer under static conditions is equal to the magnitude of gravitational acceleration, the output of the z-axis accelerometer can be determined. ;

[0024] S102. Let Euler angles be defined by the following formula:

[0025] (2)

[0026] in, express Tie The attitude transformation matrix of the system. The system represents the sensor coordinate system. The system represents the navigation coordinate system; after calibration, the sensor coordinate system and the carrier coordinate system are consistent. , and These refer to the roll angle, pitch angle, and azimuth angle of the sensor coordinate system relative to the navigation coordinate system, respectively. , , ; Indicates the original coordinate system along this coordinate system The axis rotates according to the right-hand rule. The attitude transformation matrix from the obtained coordinate system to the original coordinate system. express , or The roll angle, pitch angle, and azimuth angle at the first position are denoted as follows: , and ;

[0027] S103, the gravitational acceleration vector is The projection of the system is denoted as ,satisfy ,in, This represents the magnitude of gravitational acceleration. Let the output of the ideal triaxial accelerometer at the first position (when stationary) be... Record the first position Tie The coordinate transformation matrix of the system is ,satisfy:

[0028] (3)

[0029] in, ;

[0030] S104. Obtain the pitch angle at the first position using equation (3). and roll angle : , ,in, It is the arcsine function. It is the arctangent function A variant, with a range of ( ;

[0031] S105, Earth's rotation vector in The projection of the system is denoted as ,satisfy ,in, Let the local latitude be the value, and let the output of the hypothetical ideal three-axis gyroscope at the first position (where latitude is not specified) be denoted as . Rotate along the z-axis of an imaginary ideal three-axis gyroscope coordinate system according to the right-hand rule. The obtained coordinate system and The system coincides and satisfies The axis of the single-axis high-precision gyroscope is along the y-axis of an imaginary ideal three-axis gyroscope coordinate system. The output of the single-axis high-precision gyroscope at the first position satisfies the following:

[0032] (4)

[0033] in, , , ,

[0034] From equation (4), we get:

[0035] (5)

[0036] in, , ;

[0037] S106, The azimuth angle can be obtained from equation (5). There are also two possible solutions as two first possible azimuth angles, and the sum of these two possible solutions equals... .

[0038] Furthermore, in step S2, the two-position method of the ground-based mobile carrier is adopted, specifically as follows:

[0039] S21. When the ground-based mobile carrier starts moving at the first position and stops at the second position, the azimuth angle change value is obtained. ;

[0040] S22. When the ground mobile vehicle is stationary at the second position, the attitude determination algorithm based on incomplete dual-vector observation is used to obtain two second possible azimuth angles.

[0041] S23. Subtract the two first possible azimuth angles obtained in step S1 from the two second possible azimuth angles obtained in step S22 to obtain four possible azimuth angle change values. Then, compare these values ​​with the azimuth angle change values... By comparison, the closest value is the correct solution, thus determining the azimuth of the ground mobile vehicle at the first and second positions. The azimuth of the second position is used as the azimuth of the current position to achieve north finding.

[0042] Further, in step S21, the azimuth change value is obtained. The azimuth change value is calculated using a high-precision single-axis gyroscope with a vertical axis, an inertial measurement unit, or an odometer mounted on the left and right wheels of a ground-based mobile vehicle. .

[0043] Further, in step S21, the azimuth change value is obtained. The azimuth change value is calculated using a high-precision single-axis gyroscope with a vertical axis, an inertial measurement unit, or an odometer mounted on the left and right wheels of a ground-based mobile vehicle. Specifically:

[0044] Method 1: When the ground-based mobile vehicle starts moving at the first position, align the single-axis high-precision gyroscope vertically and enter the azimuth angular velocity measurement state. Measure the azimuth angular velocity of the ground-based mobile vehicle until it stops at the second position. Integrate the azimuth angular velocity to obtain the change in azimuth angle between the second position and the first position. ;

[0045] Method 2: The ground mobile vehicle starts moving from the first position. Simultaneously, the inertial measurement unit outputs the attitude reference system algorithm, setting the initial azimuth angle of the ground mobile vehicle to 0. This continues until the ground mobile vehicle stops at the second position, obtaining the azimuth change value. The azimuth angle change of the ground mobile vehicle at the second position relative to the first position, obtained from the attitude reference system, is recorded as the value. ;

[0046] Method 3: Mileage measuring devices are installed on both the left and right non-steering wheels of the ground mobile vehicle. The ground mobile vehicle starts traveling from the first position and stops at the second position. The road surface is level, and the mileage of the left wheel is... The mileage of the right wheel is The distance between the left and right wheels is Let the change in azimuth angle of the ground mobile carrier at the second position relative to the first position be recorded as . ,but .

[0047] Furthermore, in step S22, when the ground mobile carrier is stationary at the second position, the attitude determination algorithm based on incomplete dual-vector observation, which is the same as in step S1, is used to obtain two second possible azimuth angles.

[0048] Furthermore, the single-axis high-precision gyroscope adopts laser gyroscope, fiber optic gyroscope, hemispherical resonator gyroscope or ultra-high performance MEMS gyroscope, and the ground mobile carrier is a vehicle or ground mobile robot.

[0049] A land-based north-finding device based on a single-axis high-precision gyroscope includes a single-axis high-precision gyroscope, a dual-axis accelerometer, and a control unit.

[0050] Single-axis high-precision gyroscope: used to sense the Earth's rotational angular velocity;

[0051] Dual-axis accelerometer: used to obtain the outputs of the x-axis and y-axis accelerometers;

[0052] Control unit: Based on the output of the single-axis high-precision gyroscope and the output of the dual-axis accelerometer, the azimuth angle of the current position is determined using the land-based north-finding method based on the single-axis high-precision gyroscope described above.

[0053] Furthermore, it also includes a 90° rotation mechanism: including a rotating component and a fixed component, the fixed component being fixedly connected to the ground moving carrier, and the rotating component being used to rotate 90 degrees relative to the fixed component, so that the single-axis optical gyroscope is horizontal or vertical.

[0054] Furthermore, the control unit controls the 90° rotation mechanism to put the device into azimuth velocity measurement mode or north-finding mode. Specifically, the control unit controls the 90° rotation mechanism to make the axis of the single-axis high-precision gyroscope parallel to the vertical axis of the carrier coordinate system for measuring the azimuth velocity of the ground-based moving carrier. When north-finding is required, the control unit monitors whether the ground-based moving carrier is stationary. When the ground-based moving carrier is stationary, the control unit controls the 90° rotation mechanism to make the axis of the single-axis high-precision gyroscope perpendicular to the vertical axis of the carrier coordinate system, collects the output data of the single-axis high-precision gyroscope and the data of the dual-axis accelerometer for a set time, and uses the land-based north-finding method based on the single-axis high-precision gyroscope described above to determine the azimuth angle of the current position.

[0055] The beneficial effects of this invention are: the land-based north-finding method and device based on a single-axis high-precision gyroscope can achieve the north-finding effect of a single-axis high-precision gyroscope that is close to that of a three-axis high-precision gyroscope by using a single-axis high-precision gyroscope, with high north-finding accuracy, significantly reduced cost, and reduced size and power consumption. Attached Figure Description

[0056] Figure 1 This is a flowchart illustrating the land-based north-finding method based on a single-axis high-precision gyroscope according to an embodiment of the present invention.

[0057] Figure 2 This is a schematic diagram illustrating how a single-axis optical gyroscope is used to find north when the ground-based mobile carrier is stationary, with its axis perpendicular to the vertical axis of the carrier's coordinate system.

[0058] Figure 3 This is a schematic diagram illustrating how the azimuth angular velocity is measured with the axis of a single-axis optical gyroscope parallel to the vertical axis of the carrier coordinate system while the ground-based mobile carrier is in motion.

[0059] Figure 4 This is a schematic diagram illustrating the experimental scenario of finding north using a two-position method on a ground-based moving carrier based on a single-axis high-precision gyroscope in the embodiment.

[0060] Figure 5 This is a schematic diagram illustrating a land-based north-finding device based on a single-axis high-precision gyroscope, according to an embodiment of the present invention. Detailed Implementation

[0061] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0062] A land-based north-finding method based on a single-axis high-precision gyroscope, such as... Figure 1 This includes the following steps:

[0063] S1. When the ground-based mobile carrier is stationary at the first position, the axis of the single-axis high-precision gyroscope is perpendicular to the vertical axis of the carrier's coordinate system, and it enters the north-seeking state. Based on the output of the single-axis high-precision gyroscope and the output of the dual-axis accelerometer, the attitude determination algorithm based on incomplete dual-vector observation is used to obtain two first possible azimuth angles.

[0064] In step S1, after the ground-based mobile carrier has been stationary at the first position for a set time, the output data of the single-axis high-precision gyroscope and the output data of the x-axis and y-axis accelerometers at the stationary position are averaged. The output data of the single-axis high-precision gyroscope at the first position is recorded as follows: The x-axis and y-axis accelerometer outputs at the first position are respectively denoted as... and The outputs of both the gyroscope and the accelerometer were normalized by dividing the gyroscope's output by the Earth's rotational angular velocity and the accelerometer's output by the gravitational acceleration.

[0065] In step S1, the axial direction of the single-axis high-precision gyroscope is along the x-axis or y-axis of the carrier coordinate system, or the angle between the axial direction of the single-axis high-precision gyroscope and the y-axis of the carrier coordinate system is... .

[0066] In step S1, an attitude determination algorithm based on incomplete two-vector observations is used to obtain two first possible azimuth angles, specifically,

[0067] S11. The axis of the single-axis high-precision gyroscope is along the x-axis direction of the carrier coordinate system. Let the output of the hypothetical y-axis and z-axis optical gyroscope in the first static position be... and The hypothetical z-axis accelerometer output in the first stationary position is denoted as... The following equation is satisfied:

[0068] (1)

[0069] in, These are the x-axis accelerometer outputs and y-axis accelerometer outputs, respectively, and have already been normalized. The output is from a single-axis high-precision gyroscope and has already been normalized. Let be the angle between the gravity vector and the Earth's rotation vector, satisfying ,in, This is the local latitude value;

[0070] In step S1, the carrier coordinate system can be the right front upper coordinate system of the ground mobile carrier, and the coordinate axes of the sensor coordinate system are along the direction of the sensitive axis of the inertial sensor. After calibration, the sensor coordinate system is consistent with the carrier coordinate system.

[0071] S12. Given the z-axis orientation, calculate the z-axis accelerometer output using equation (a) in (1);

[0072] In step S12, since the ground-based mobile carrier usually does not overturn, and the z-axis accelerometer points upwards from the ground-based mobile carrier, the output of the z-axis accelerometer must be greater than 0.

[0073] S13, after obtaining the z-axis accelerometer output In this case, by solving equations (b) and (c) in equation (1), the output of the y-axis optical gyroscope can be obtained. and z-axis optical gyroscope output Two possible solutions;

[0074] In step S13, although the y-axis and z-axis optical gyroscopes are not present, their output values ​​can be calculated. and In seeking In the case of solving equations (1) and (b) simultaneously, we can obtain the following: and The two possible solutions are:

[0075] First possible solution:

[0076] ,

[0077] ;

[0078] Second possible solution:

[0079] ,

[0080] .

[0081] S14. Two first possible azimuth angles are calculated using a three-axis attitude determination algorithm, namely the TRIAD algorithm or an optimized attitude determination algorithm.

[0082] In step S14, the three-axis attitude determination algorithm, namely the TRIAD algorithm, is used to calculate two first possible azimuth angles, specifically,

[0083] S141. The attitude transformation matrix at the first position is calculated based on the TRIAD algorithm or an optimized attitude determination algorithm.

[0084] (2) Among them, express Tie The attitude transformation matrix of the system. The system represents the sensor coordinate system, with the coordinate axes along the sensitive axes of the inertial sensor. The system refers to the navigation coordinate system, which is defined as the local northeast-sky coordinate system. The vector representing gravitational acceleration is located at... The projection under the system has been normalized to satisfy... T represents the transpose of a matrix. Indicates the Earth's rotation vector at The projection under the system has been normalized to satisfy... ,also, , ;

[0085] S142. Euler angles are defined by the following formula.

[0086] (3)

[0087] in , and These refer to the roll angle, pitch angle, and azimuth angle of the sensor coordinate system relative to the navigation coordinate system, respectively. , , , Indicates the original coordinate system along this coordinate system The axis rotates according to the right-hand rule. The attitude transformation matrix from the obtained coordinate system to the original coordinate system. express , or ;

[0088] S143. Obtain the first possible azimuth angle at the first position according to equations (2) and (3). :

[0089]

[0090] in, , It is the arctangent function A variant, with a range of ( First possible azimuth Describing the ground-based mobile vehicle at the first location as facing north, due to and There are two possible solutions, the first possible azimuth angle There are also two possible solutions as two first possible azimuth angles.

[0091] In step S14, the attitude transformation matrix is ​​first calculated, and then two first possible azimuth angles are obtained from the attitude transformation matrix. An optimization-based attitude determination algorithm can be used to solve this problem. Algorithms such as QUEST and FORM are used. After obtaining two possible solutions as the first possible azimuth angles, it is necessary to determine the unique positive solution.

[0092] In step S1, an attitude determination algorithm based on incomplete two-vector observations is used to obtain two first possible azimuth angles. In another specific example, specifically,

[0093] Given the orientation of the z-axis accelerometer, and based on the fact that the magnitude of the triaxial accelerometer under static conditions is the magnitude of gravitational acceleration, the output of the z-axis accelerometer can be determined.

[0094] The roll and pitch angles of the ground mobile vehicle are determined based on the output of the triaxial accelerometer. The azimuth angle of the ground mobile vehicle is used as an undetermined coefficient, and the Earth's rotation vector is projected onto the vehicle coordinate system.

[0095] Based on the output of a single-axis high-precision gyroscope, two first possible azimuth angles of the ground mobile carrier are determined.

[0096] In step S1, an attitude determination algorithm based on incomplete two-vector observations is used to obtain two first possible azimuth angles. In another specific example, this includes the following steps:

[0097] S101, the ground-based mobile carrier remains stationary at the first position for a set time, and the angle between the axis of the single-axis high-precision gyroscope and the y-axis of the carrier coordinate system is... The output of the single-axis high-precision gyroscope at the first position is denoted as... The outputs of the x-axis accelerometer and y-axis accelerometer at the first position are respectively denoted as... and Given that the z-axis accelerometer's axial orientation is known, and its output is greater than 0, and considering that the magnitude of the triaxial accelerometer under static conditions is equal to the magnitude of gravitational acceleration, the z-axis accelerometer output can be determined. ;

[0098] S102. Let Euler angles be defined by the following formula:

[0099] (4)

[0100] in, express Tie The attitude transformation matrix of the system. The system represents the sensor coordinate system. The system represents the navigation coordinate system; after calibration, the sensor coordinate system is consistent with the carrier coordinate system. , and These refer to the roll angle, pitch angle, and azimuth angle of the sensor coordinate system relative to the navigation coordinate system, respectively. , , ; Indicates the original coordinate system along this coordinate system The axis rotates according to the right-hand rule. The attitude transformation matrix from the obtained coordinate system to the original coordinate system. express , or The roll angle, pitch angle, and azimuth angle at the first position are denoted as follows: , and ;

[0101] S103, the gravitational acceleration vector is The projection of the system is denoted as ,satisfy ,in, This represents the magnitude of gravitational acceleration. Let the output of the ideal triaxial accelerometer at the first position (when stationary) be... Record the first position Tie The coordinate transformation matrix of the system is ,satisfy:

[0102] (5)

[0103] in, ;

[0104] S104. Obtain the pitch angle at the first position using equation (5). and roll angle : , ,in, It is the arcsine function. It is the arctangent function A variant, with a range of ( ;

[0105] S105, Earth's rotation vector in The projection of the system is denoted as ,satisfy ,in, Let the local latitude be the value, and let the output of the hypothetical ideal three-axis gyroscope at the first position (where latitude is not specified) be denoted as . Rotate along the z-axis of an imaginary ideal three-axis gyroscope coordinate system according to the right-hand rule. The obtained coordinate system and The system coincides and satisfies The axis of the single-axis high-precision gyroscope is along the y-axis of an imaginary ideal three-axis gyroscope coordinate system. The output of the single-axis high-precision gyroscope at the first position satisfies the following:

[0106] (6)

[0107] in, , , ,

[0108] From equation (6), we get:

[0109] (7)

[0110] in, , ;

[0111] In step S105, the axial direction of the single-axis optical gyroscope is along the y-axis of the carrier coordinate system, i.e. At 0°, the Earth's rotation vector is The projection of the system is denoted as ,satisfy ,in, Let be the local latitude, and let the output of the ideal three-axis gyroscope at the first stationary position be . ,satisfy The average output of the y-axis optical gyroscope at the first position satisfies: Thus obtain satisfy:

[0112]

[0113] S106, The azimuth angle can be obtained from equation (7). There are two possible solutions as two first possible azimuth angles, and the sum of these two possible solutions equals... .

[0114] S2. Determine the azimuth of the current position by comparing the two first possible azimuth angles with the azimuth obtained by the navigation system, or by using the two-position method of the ground mobile carrier.

[0115] In step S2, the two-position method of the ground-based mobile carrier is adopted, specifically as follows:

[0116] S21. When the ground-based mobile carrier starts moving at the first position and stops at the second position, the azimuth angle change value is obtained. ;

[0117] In step S21, the azimuth change value is obtained. The azimuth change value is calculated using a high-precision single-axis gyroscope with a vertical axis, an inertial measurement unit, or an odometer mounted on the left and right wheels of a ground-based mobile vehicle. Specifically:

[0118] Method 1: When the ground-based mobile vehicle starts moving at the first position, align the single-axis high-precision gyroscope vertically and enter the azimuth angular velocity measurement state. Measure the azimuth angular velocity of the ground-based mobile vehicle until it stops at the second position. Integrate the azimuth angular velocity to obtain the change in azimuth angle between the second position and the first position. ;

[0119] Method 2: The ground mobile vehicle starts moving from the first position. Simultaneously, the inertial measurement unit outputs the attitude reference system algorithm, setting the initial azimuth angle of the ground mobile vehicle to 0. This continues until the ground mobile vehicle stops at the second position, obtaining the azimuth change value. The azimuth angle change of the ground mobile vehicle at the second position relative to the first position, obtained from the attitude reference system, is recorded as the value. ;

[0120] Method 3: Mileage measuring devices are installed on both the left and right non-steering wheels of the ground mobile vehicle. The ground mobile vehicle starts traveling from the first position and stops at the second position. The road surface is level, and the mileage of the left wheel is... The mileage of the right wheel is The distance between the left and right wheels is Let the change in azimuth angle of the ground mobile carrier at the second position relative to the first position be recorded as . ,but .

[0121] S22. When the ground mobile vehicle is stationary at the second position, the attitude determination algorithm based on incomplete dual-vector observation is used to obtain two second possible azimuth angles.

[0122] In step S22, the attitude determination algorithm based on incomplete dual-vector observation, the same as in step S1, is used to obtain two second possible azimuth angles. The axis of the single-axis high-precision gyroscope is horizontally parallel to the XY plane of the carrier coordinate system. The axes of the sensor coordinate system and the carrier coordinate system are consistent. Based on the outputs of the single-axis high-precision gyroscope, the x-axis accelerometer, and the y-axis accelerometer, the attitude determination algorithm based on incomplete dual-vector observation is used to obtain two second possible azimuth angles. .

[0123] S23. Subtract the two first possible azimuth angles obtained in step S1 from the two second possible azimuth angles obtained in step S22 to obtain four possible azimuth angle change values. Then, compare these values ​​with the azimuth angle change values... By comparison, the closest value is the correct solution, thus determining the azimuth of the ground mobile vehicle at the first and second positions. The azimuth of the second position is used as the azimuth of the current position to achieve north finding.

[0124] In step S2, the azimuth of the current position is determined by comparing the two first possible azimuth angles with the azimuths obtained from other navigation systems. Specifically,

[0125] On a ground-based mobile vehicle, the GNSS and IMU integrated navigation system outputs azimuth and position information. When the ground-based mobile vehicle enters a place where GNSS signals are lost, such as a tunnel, underground parking lot, or overpass, the azimuth error accumulates over time. The GNSS and IMU integrated navigation system outputs a azimuth, which is compared with the two first possible azimuth angles obtained in step S1. The closer first possible azimuth angle is the azimuth angle of the current position, thereby achieving north finding.

[0126] Optionally, in step S2, the azimuth of the current position is determined by comparing the two first possible azimuth angles with the azimuths obtained from other navigation systems. Specifically,

[0127] The magnetic sensor and inertial navigation system on the ground mobile carrier output the azimuth. The magnetic sensor is susceptible to interference. The obtained azimuth angle is compared with the two first possible azimuth angles obtained in step S1. The closer first possible azimuth angle is the azimuth angle of the current position, thereby realizing north finding.

[0128] This land-based north-finding method based on a single-axis high-precision gyroscope uses a laser gyroscope, fiber optic gyroscope, hemispherical resonator gyroscope, or ultra-high-performance MEMS gyroscope, and the ground mobile carrier is a vehicle or a ground mobile robot.

[0129] The embodiment also provides a land-based north-finding device based on a single-axis high-precision gyroscope, including a single-axis high-precision gyroscope, a dual-axis accelerometer, and a control unit.

[0130] Single-axis high-precision gyroscope: used to sense the Earth's rotational angular velocity;

[0131] Dual-axis accelerometer: used to obtain the outputs of the x-axis and y-axis accelerometers;

[0132] Control unit: Based on the output of the single-axis high-precision gyroscope and the output of the dual-axis accelerometer, the azimuth angle of the current position is determined using the land-based north-finding method based on the single-axis high-precision gyroscope described above.

[0133] like Figure 5 It also includes a 90° rotation mechanism: including a rotating component and a fixed component. The fixed component is fixedly connected to the ground moving carrier, and the rotating component is used to rotate 90 degrees relative to the fixed component, so that the single-axis optical gyroscope is horizontal or vertical.

[0134] This land-based north-finding device based on a single-axis high-precision gyroscope uses a control unit to control a 90° rotation mechanism, enabling the device to enter either azimuth angular velocity measurement or north-finding mode. Specifically, the 90° rotation mechanism is controlled to align the axis of the single-axis high-precision gyroscope parallel to the vertical axis of the carrier coordinate system, used to measure the azimuth angular velocity of the ground-based moving carrier. When north-finding is required, the device monitors whether the ground-based moving carrier is stationary. When the ground-based moving carrier is stationary, the 90° rotation mechanism is controlled to align the axis of the single-axis high-precision gyroscope perpendicular to the vertical axis of the carrier coordinate system. Data from the single-axis high-precision gyroscope and dual-axis accelerometers are collected over a set time. The azimuth angle of the current position is determined using the land-based north-finding method based on the single-axis high-precision gyroscope described above.

[0135] The control unit uses a zero-speed detection algorithm to monitor whether the ground moving vehicle is stationary. The zero-speed detection algorithm determines whether the output of the gyroscope or accelerometer is less than a set threshold, or whether the speed output of the navigation system is zero.

[0136] This land-based north-finding method and device, based on a single-axis high-precision gyroscope, measures the azimuth angular velocity by aligning the gyroscope's axis along the vertical axis of the carrier's coordinate system. When north-finding is required, a 90° rotation mechanism is used to make the gyroscope's axis perpendicular to the vertical axis of the carrier's coordinate system. When the ground-based mobile carrier is stationary in the first position, two possible azimuth angles are obtained using an attitude determination algorithm based on incomplete dual-vector observation, based on the outputs of the single-axis high-precision gyroscope and the dual-axis accelerometer. The azimuth angle is then determined using prior azimuth information or the two-position method of the ground-based mobile carrier. By utilizing a single-axis high-precision gyroscope, the north-finding and azimuth angular velocity measurement effects of a three-axis high-precision gyroscope are achieved, while significantly reducing costs.

[0137] By using a 90° rotation mechanism to align the axis of a single-axis high-precision gyroscope with the vertical axis of the carrier coordinate system, the azimuth angular velocity of the ground mobile carrier can be measured. When GNSS signals are lost, the divergence of azimuth error is a major problem in the positioning of ground mobile carriers. Utilizing a single-axis high-precision gyroscope to measure the azimuth angular velocity will significantly improve the accuracy of azimuth measurement, thereby enabling the continuous acquisition of high-precision azimuth.

[0138] This land-based north-finding method based on a single-axis high-precision gyroscope achieves north-finding and azimuth angular velocity measurement effects comparable to or close to those of a three-axis high-precision gyroscope by employing a single-axis optical gyroscope. It boasts high north-finding accuracy, significantly reduced costs, and smaller size and power consumption.

[0139] In the embodiments, for cases where only north-finding is required, method 2 or method 3 can be used to obtain the azimuth change. In this case, a 90° rotation mechanism is unnecessary, allowing the single-axis high-precision gyroscope to remain perpendicular to the vertical axis of the carrier's coordinate system, thus reducing both cost and size. This invention requires the carrier to remain relatively level without significant swaying, making it suitable for ground-based mobile carriers.

[0140] The experimental verification of this land-based north-finding method and device based on a single-axis high-precision gyroscope in the embodiment is as follows:

[0141] like Figure 4 As shown, the vehicle is equipped with a laser gyroscope-based IMU and a MEMS-based IMU, employing a single-axis laser gyroscope and a dual-axis accelerometer. The method uses S11-S14 to calculate the possible azimuth angle values ​​for the first and second positions, and method 2 to calculate the azimuth angle change value. North-finding was performed using steps S21-S23. The azimuth angle obtained by substituting the 6-axis output of the laser gyroscope-based IMU into the TRIAD algorithm had high accuracy and was used as a reference value to verify the method error obtained by the invented method. Four experiments were conducted, and the results are shown in Table 1 when the axis of the single-axis laser gyroscope used was along the x-axis of the carrier coordinate system.

[0142] Table 1. Axial axis of single-axis laser gyroscope along the x-axis of the carrier coordinate system

[0143]

[0144] When the axis of the single-axis laser gyroscope used is along the y-axis of the carrier coordinate system, the results are shown in Table 2:

[0145] Table 2. Axial axis of single-axis laser gyroscope along the y-axis of the carrier coordinate system

[0146]

[0147] As can be seen from the results in Tables 1 and 2, the azimuth angle obtained by the method in the embodiment is close to the reference value, indicating that the north-finding method of the embodiment is effective and has high accuracy. Meanwhile, according to the error propagation characteristics of the method in the embodiment, when the axis of the single-axis laser gyroscope used is along the x-axis of the carrier coordinate system, if the azimuth angle is close to 90° or 270°, the error is large. As shown in Table 1, when the azimuth angle is 232.9°, it is close to 270°, and the north-finding error becomes larger. When the axis of the single-axis laser gyroscope used is along the y-axis of the carrier coordinate system, if the azimuth angle is close to 0° or 180°, the error is large. As shown in Table 2, when the azimuth angle is 191.47° or 182.72°, it is close to 180°, and the north-finding error becomes larger. Therefore, when the axis of the single-axis laser gyroscope used is along the x-axis of the carrier coordinate system, the vehicle is not traveling in an east-west direction, and the north-finding accuracy is high; when the axis of the single-axis laser gyroscope used is along the y-axis of the carrier coordinate system, the vehicle is not traveling in a north-south direction, and the north-finding accuracy is high.

[0148] The above are merely preferred embodiments of the present invention, but do not limit the patent scope of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of the present invention specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the patent protection scope of the present invention.

Claims

1. A land-based north-finding method based on a single-axis high-precision gyroscope, characterized in that, Includes the following steps: S1. When the ground-based mobile carrier is stationary at the first position, the axis of the single-axis high-precision gyroscope is perpendicular to the vertical axis of the carrier's coordinate system, and it enters the north-seeking state. Based on the output of the single-axis high-precision gyroscope and the output of the dual-axis accelerometer, the attitude determination algorithm based on incomplete dual-vector observation is used to obtain two first possible azimuth angles. In step S1, the angle between the axis of the single-axis high-precision gyroscope along the x-axis or y-axis of the carrier coordinate system, or the angle between the axis of the single-axis high-precision gyroscope and the y-axis of the carrier coordinate system, is arbitrary. ; In step S1, an attitude determination algorithm based on incomplete two-vector observations is used to obtain two first possible azimuth angles, specifically, S11. The axis of the single-axis high-precision gyroscope is along the x-axis direction of the carrier coordinate system. Let the output of the hypothetical y-axis and z-axis optical gyroscope in the first static position be... and The hypothetical z-axis accelerometer output in the first stationary position is denoted as... The following equation is satisfied: (1) in, These are the x-axis and y-axis accelerometer outputs, respectively, and have already undergone normalization by dividing by the gravitational acceleration value. The output is from a single-axis high-precision gyroscope and has been normalized by dividing by the Earth's rotational angular velocity. Let be the angle between the gravity vector and the Earth's rotation vector, satisfying ,in, This is the local latitude value; S12. Given the z-axis orientation, calculate the z-axis accelerometer output using equation (a) in (1); S13, after obtaining the z-axis accelerometer output In this case, by solving equations (b) and (c) in equation (1), the output of the y-axis optical gyroscope can be obtained. and z-axis optical gyroscope output Two possible solutions; S14. Two first possible azimuth angles are calculated using a three-axis attitude determination algorithm, namely the TRIAD algorithm or an optimized attitude determination algorithm. In step S1, an attitude determination algorithm based on incomplete two-vector observations is used to obtain two first possible azimuth angles, specifically, S101, the ground-based mobile carrier remains stationary at the first position for a set time, and the angle between the axis of the single-axis high-precision gyroscope and the y-axis of the carrier coordinate system is... The output of the single-axis high-precision gyroscope at the first position is denoted as... The outputs of the x-axis accelerometer and y-axis accelerometer at the first position are respectively denoted as... and Given the axial orientation of the z-axis accelerometer, and based on the fact that the magnitude of the triaxial accelerometer under static conditions is equal to the magnitude of gravitational acceleration, the output of the z-axis accelerometer can be determined. ; S102. Let Euler angles be defined by the following formula: (2) in, express Tie The attitude transformation matrix of the system. The system represents the sensor coordinate system. The system represents the navigation coordinate system; after calibration, the sensor coordinate system and the carrier coordinate system are consistent. , and These refer to the roll angle, pitch angle, and azimuth angle of the sensor coordinate system relative to the navigation coordinate system, respectively. , , ; Indicates the original coordinate system along this coordinate system The axis rotates according to the right-hand rule. The attitude transformation matrix from the obtained coordinate system to the original coordinate system. express , or The roll angle, pitch angle, and azimuth angle at the first position are denoted as follows: , and ; S103, the gravitational acceleration vector is The projection of the system is denoted as ,satisfy ,in, This represents the magnitude of gravitational acceleration. Let the output of the ideal triaxial accelerometer at the first position (when stationary) be... Record the first position Tie The coordinate transformation matrix of the system is ,satisfy: (3) in, ; S104. Obtain the pitch angle at the first position using equation (3). and roll angle : , ,in, It is the arcsine function. It is the arctangent function A variant, with a range of ( ; S105, Earth's rotation vector in The projection of the system is denoted as ,satisfy ,in, Let the local latitude be the value, and let the output of the hypothetical ideal three-axis gyroscope at the first position (where latitude is not specified) be denoted as . Rotate along the z-axis of an imaginary ideal three-axis gyroscope coordinate system according to the right-hand rule. The obtained coordinate system and The system coincides and satisfies The axis of the single-axis high-precision gyroscope is along the y-axis of an imaginary ideal three-axis gyroscope coordinate system. The output of the single-axis high-precision gyroscope at the first position satisfies the following: （4） in, , , , From equation (4), we get: （5） in, , ; S106, The azimuth angle can be obtained from equation (5). There are also two possible solutions as two first possible azimuth angles, and the sum of these two possible solutions equals... ; S2. Determine the azimuth of the current position by comparing the two first possible azimuth angles with the azimuth obtained by the navigation system, or by using the two-position method of the ground mobile vehicle. In step S2, the two-position method of the ground-based mobile carrier is adopted, specifically as follows: S21. When the ground-based mobile carrier starts moving at the first position and stops at the second position, the azimuth angle change value is obtained. ; S22. When the ground mobile vehicle is stationary at the second position, the attitude determination algorithm based on incomplete dual-vector observation is used to obtain two second possible azimuth angles. S23. Subtract the two first possible azimuth angles obtained in step S1 from the two second possible azimuth angles obtained in step S22 to obtain four possible azimuth angle change values. Then, compare these values ​​with the azimuth angle change values... By comparison, the closest value is the correct solution, thus determining the azimuth of the ground mobile vehicle at the first and second positions. The azimuth of the second position is used as the azimuth of the current position to achieve north finding.

2. The land-based north-finding method based on a single-axis high-precision gyroscope as described in claim 1, characterized in that: In step S21, the azimuth change value is obtained. The azimuth change value is calculated using a high-precision single-axis gyroscope with a vertical axis, an inertial measurement unit, or an odometer mounted on the left and right wheels of a ground-based mobile vehicle. .

3. The land-based north-finding method based on a single-axis high-precision gyroscope as described in claim 2, characterized in that: In step S21, the azimuth change value is obtained. The azimuth change value is calculated using a high-precision single-axis gyroscope with a vertical axis, an inertial measurement unit, or an odometer mounted on the left and right wheels of a ground-based mobile vehicle. Specifically: Method 1: When the ground-based mobile vehicle starts moving at the first position, align the single-axis high-precision gyroscope vertically and enter the azimuth angular velocity measurement state. Measure the azimuth angular velocity of the ground-based mobile vehicle until it stops at the second position. Integrate the azimuth angular velocity to obtain the change in azimuth angle between the second position and the first position. ; Method 2: The ground mobile vehicle starts moving from the first position. Simultaneously, the inertial measurement unit outputs the attitude reference system algorithm, setting the initial azimuth angle of the ground mobile vehicle to 0. This continues until the ground mobile vehicle stops at the second position, obtaining the azimuth change value. The azimuth angle change of the ground mobile vehicle at the second position relative to the first position, obtained from the attitude reference system, is recorded as the value. ; Method 3: Mileage measuring devices are installed on both the left and right non-steering wheels of the ground mobile vehicle. The ground mobile vehicle starts traveling from the first position and stops at the second position. The road surface is level, and the mileage of the left wheel is... The mileage of the right wheel is The distance between the left and right wheels is Let the change in azimuth angle of the ground mobile carrier at the second position relative to the first position be recorded as . ,but .

4. The land-based north-finding method based on a single-axis high-precision gyroscope as described in claim 1, characterized in that: In step S22, when the ground mobile carrier is stationary at the second position, the attitude determination algorithm based on incomplete dual-vector observation, which is the same as in step S1, is used to obtain two second possible azimuth angles.

5. The land-based north-finding method based on a single-axis high-precision gyroscope as described in claim 1, characterized in that: The single-axis high-precision gyroscope uses laser gyroscopes, fiber optic gyroscopes, hemispherical resonator gyroscopes, or ultra-high performance MEMS gyroscopes, and the ground mobile carrier is a vehicle or a ground mobile robot.

6. A land-based north-finding device based on a single-axis high-precision gyroscope, characterized in that: Includes a single-axis high-precision gyroscope, a dual-axis accelerometer, and a control unit. Single-axis high-precision gyroscope: used to sense the Earth's rotational angular velocity; Dual-axis accelerometer: used to obtain the outputs of the x-axis and y-axis accelerometers; Control unit: Based on the output of the single-axis high-precision gyroscope and the output of the dual-axis accelerometer, the azimuth angle of the current position is determined using the land-based north-finding method based on the single-axis high-precision gyroscope as described in any one of claims 1-5.

7. The land-based north-finding device based on a single-axis high-precision gyroscope as described in claim 6, characterized in that: It also includes a 90° rotation mechanism: including a rotating component and a fixed component. The fixed component is fixedly connected to the ground moving carrier, and the rotating component is used to rotate 90 degrees relative to the fixed component, so that the single-axis optical gyroscope is horizontal or vertical.

8. The land-based north-finding device based on a single-axis high-precision gyroscope as described in claim 7, characterized in that: The control unit controls the 90° rotation mechanism to put the device into azimuth velocity measurement mode or north-finding mode. Specifically, it controls the 90° rotation mechanism to make the axis of the single-axis high-precision gyroscope parallel to the vertical axis of the carrier coordinate system for measuring the azimuth velocity of the ground-based moving carrier. When north-finding is required, it monitors whether the ground-based moving carrier is stationary. When the ground-based moving carrier is stationary, it controls the 90° rotation mechanism to make the axis of the single-axis high-precision gyroscope perpendicular to the vertical axis of the carrier coordinate system, collects the output data of the single-axis high-precision gyroscope and the data of the dual-axis accelerometer for a set time, and uses the land-based north-finding method based on the single-axis high-precision gyroscope as described in any one of claims 1-5 to determine the azimuth angle of the current position.

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