Three-dimensional ultrasonic wind speed and wind direction measurement and calculation method for attitude compensation

Abstract

The invention discloses a three-dimensional ultrasonic wind speed and wind direction measurement and calculation method for attitude compensation, and belongs to the technical field of wind speed and wind direction measurement. The method comprises the following steps: controlling a three-dimensional ultrasonic probe array to emit and receive ultrasonic waves according to downstream and countercurrent directions to obtain flight time, calculating wind speed components in each measuring axis direction based on a time difference method, and converting the wind speed components from a measuring axis coordinate system to a carrier coordinate system according to a fixed space geometrical relationship of the probe array. And the IMU attitude and heading measurement module outputs an attitude rotation matrix of the carrier coordinate system relative to the east-north-sky geographic coordinate system in real time, performs attitude compensation on a wind speed component under the carrier coordinate system, converts the wind speed component into the east-north-sky geographic coordinate system, and calculates to obtain accurate wind speed and wind direction. Dynamic attitude compensation is introduced, the problem of measurement errors caused by inclination and rotation of a carrier in a movable base scene is effectively solved, meanwhile, a static base measurement mode is compatible, and the measurement precision and reliability in a complex application scene are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wind speed and direction measurement, and particularly relates to a three-dimensional ultrasonic wind speed and direction measurement method with attitude compensation. BACKGROUND

[0002] Wind speed and direction are important parameters in meteorological observation, environmental monitoring and other fields. Existing three-dimensional ultrasonic wind speed and direction instruments usually use ultrasonic time-of-flight difference method to measure wind speed components. The principle is to emit and receive ultrasonic signals by an ultrasonic transducer array installed in a specific geometric structure, and to calculate wind speed and direction according to the time difference of ultrasonic propagation in the forward and reverse directions. Such instruments have the advantages of no rotating parts, fast response speed and high measurement accuracy, and have been widely used in meteorological observation and aerodynamics experiments.

[0003] Most existing three-dimensional ultrasonic wind speed and direction instruments are designed based on static base application scenarios, and usually assume that the instrument installation position is fixed, and that the carrier coordinate system is consistent with the geographic coordinate system. Under this condition, the measured wind speed components can be directly mapped to the geographic coordinate system, thereby obtaining the true wind speed and direction. However, in actual applications, three-dimensional wind speed instruments often need to be installed on mobile platforms such as ocean buoys, ships or vehicles. At this time, due to the change of the carrier attitude, dynamic deviation will occur between the carrier coordinate system and the geographic coordinate system, resulting in significant errors in wind speed projection calculation. Especially in the case of large attitude motion of the platform, the measurement error will quickly accumulate, seriously affecting the reliability of the measurement results.

[0004] Therefore, there is an urgent need for a three-dimensional ultrasonic wind speed and direction measurement system that can operate stably in a dynamic base environment. The system should have an attitude compensation function, i.e. even if the measurement system tilts or rotates during operation, it can still accurately calculate the wind speed and direction in real time to meet the needs of complex application scenarios for wind field parameter measurement. SUMMARY

[0005] The purpose of the present application is to provide a three-dimensional ultrasonic wind speed and direction measurement method with attitude compensation, which can detect the deviation between the measurement system carrier coordinate system and the northeast geographic coordinate system caused by tilting or rotation of the measurement system in real time, and realize attitude compensation to solve the wind speed and direction measurement error problem in the existing technology during dynamic base operation.

[0006] To achieve the above purpose, the present application adopts the following technical solutions:

[0007] A three-dimensional ultrasonic wind speed and direction measurement method with attitude compensation is realized based on an ultrasonic transducer array installed in a specific geometric structure and an IMU attitude measurement module.

[0008] The ultrasonic transducer array comprises six ultrasonic transducers, a base, a support rod and a transducer connecting rod. Each ultrasonic transducer works based on the direct and inverse piezoelectric effect and has the functions of transmitting and receiving ultrasonic waves. Each two transducers are oppositely arranged to form a measuring axis, thereby forming three measuring axes U, V and W. In each measuring axis, the first transducer transmits and the second transducer receives to form a forward flow process, and the second transducer transmits and the first transducer receives to form a reverse flow process. The ultrasonic wave flight times in the forward flow and reverse flow processes are measured respectively to provide original data for the wind speed calculation based on the time difference method.

[0009] The base, the support rod and the transducer connecting rod jointly form a mechanical support structure of the ultrasonic transducer array, which is used for fixing the transducers and arranging electrical signal lines. All the signal lines are led through the internal cavities of the above components and are finally led out from below the base. The angle between the straight line of each measuring axis and the vertical direction is 54.74°, and the projections of the three measuring axes on the horizontal plane are mutually 120°. The geometric layout makes the three axes U, V and W orthogonal to each other in the three-dimensional space and jointly form a measuring axis coordinate system to meet the coordinate conversion formula of the wind speed components from the measuring axis coordinate system to the carrier coordinate system.

[0010] The excitation and reception of the ultrasonic transducer array are realized by a special electronic device. The excitation device generates an electrical signal of a specific frequency and amplitude to drive the transmitting transducer. The receiving device processes and detects the weak echo signal output by the receiving transducer and accurately measures the flight time of the ultrasonic wave from transmission to reception.

[0011] The IMU attitude measurement module is fixedly installed in the central region of the base and is used for measuring the attitude of the system carrier coordinate system relative to the northeast geographical coordinate system in real time. The module integrates a multi-axis sensor and an internal processor and can automatically calculate and output the attitude angle of the carrier coordinate system relative to the northeast coordinate system in the form of Euler angles wherein φ is the heading angle, θ is the pitch angle, and ψ is the roll angle.

[0012] The three-dimensional ultrasonic wind speed and direction measurement calculation method with attitude compensation comprises the following steps S1-S5:

[0013] S1: A specific frequency and amplitude excitation signal is transmitted by the ultrasonic transducer excitation device to drive the transmitting transducers of the three measuring axes U, V and W of the three-dimensional ultrasonic transducer array in sequence to transmit ultrasonic waves, and the receiving transducers receive the ultrasonic signals. The received ultrasonic signals are processed by the ultrasonic signal detection device, and the ultrasonic wave flight times from transmission to reception are recorded. Each measuring axis completes the transmission and reception process in the forward flow and reverse flow directions, and six ultrasonic wave flight time data t u1-u2 , t u2-u1 , t v1-v2 , tv2-v1 , t w1-w2 , t w2-w1 , t u1-u2 , t u2-u1 , t v1-v2 , t v2-v1 , t w1-w2 , t w2-w1 , t

[0014] U-axis upwind ultrasonic wave flight time:

[0015] U-axis downwind ultrasonic wave flight time:

[0016] wherein L is the distance between the two ultrasonic transducers, c is the propagation speed of the ultrasonic wave, v is the wind speed of the current measurement axis U, t u1-u2 is the upwind flight time, and t u2-u1 is the downwind flight time.

[0017] S2: Based on the six ultrasonic wave flight times t u1-u2 , t u2-u1 , t v1-v2 , t v2-v1 , t w1-w2 , t w2-w1 obtained in step S1, the wind speed components V u , V v , V w in the measurement axis coordinate system of the measurement axes U, V, and W are calculated respectively by using the ultrasonic time difference method.

[0018]

[0019] wherein L is the fixed distance between the two ultrasonic transducers on each measurement axis;

[0020] S3: Based on the fixed spatial geometric relationship between the U, V, and W measurement axes and the measurement system carrier coordinate system in the three-dimensional ultrasonic transducer array, the wind speed components V u , V v , V w in the measurement axis coordinate system obtained in step S2 are converted to the wind speed components V x0 , V y0 , V z0 in the measurement system carrier coordinate system through a preset coordinate conversion formula.The measurement system carrier coordinate system is a coordinate system fixedly connected with a mechanical structure base on which the transducer array is installed, the X0 axis, the Y0 axis of which are parallel to the base plane, and the Z0 axis is perpendicular to the base plane, and the conversion formula is as follows:

[0021] V x0 = cos(-45°)·V u + sin(-45°)·V v

[0022] V y0 =(-sin(-45°)·V u + cos(-45°)·V v )·cos(-54.74°)+sin(-54.74°)·V w ;

[0023] V z0 =(-sin(-45°)·V u + cos(-45°)·V v )·(-sin(-54.74°))+cos(-54.74°)·V w

[0024] S4: The three-dimensional ultrasonic wind speed and direction measurement system supports static base measurement and dynamic base measurement modes. In the static base measurement mode, the measurement system carrier coordinate system X0Y0Z0 and the northeast geographical coordinate system XYZ are required to be completely aligned during installation, and the measurement system is required to remain fixed in the attitude during operation. At this time, attitude compensation is not required, V x , V y , V z , V x0 , V y0 , V z0 are consistent. In the dynamic base measurement mode, the base of the measurement system installation will change in attitude, for example, in the scenarios of ocean floating, vehicle-mounted, etc. The measurement system carrier coordinate system X0Y0Z0 cannot be aligned with the northeast geographical coordinate system XYZ, and is in a dynamic change process. In this case, attitude compensation is required, and the IMU attitude measurement module outputs the attitude Euler angle of the measurement system carrier coordinate system relative to the northeast geographical coordinate system A rotation matrix is constructed to convert the three-dimensional wind speed components V x0 , V y0 , V z0 in the carrier coordinate system in step S3 to the northeast geographical coordinate system wind speed vector V x , V y , V z after attitude compensation, so as to realize attitude compensation of the wind speed components and eliminate errors. The solving process includes:

[0025]

[0026] wherein φ, θ, are the heading angle, the pitch angle and the roll angle of the sequential rotation around the Z0 axis, the Y0 axis and the X0 axis of the measurement system carrier coordinate system respectively;

[0027] S5: obtaining the wind speed vector V x , V y , V z in the east-north-up geographic coordinate system after the attitude compensation according to step S4

[0028]

[0029] Wind direction = arctan2 (V x , V y ) · 180 / π + 180, the wind direction angle range is defined as 0°-360°. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a schematic diagram of the tilt rotation of a three-dimensional ultrasonic wind speed and direction measurement system;

[0031] Figure 2 is a schematic diagram of the ultrasonic transducer array structure installed according to a specific geometric structure;

[0032] Figure 3 is a flow chart of a three-dimensional ultrasonic wind speed and direction measurement solution method with attitude compensation;

[0033] In the figure, 1 is a support rod, 2 is an ultrasonic transducer W1, 3 is an ultrasonic transducer U1, 4 is an ultrasonic transducer V2, 5 is a base, 6 is a transducer connecting rod, 7 is an ultrasonic transducer V1, 8 is an ultrasonic transducer U2, 9 is an ultrasonic transducer W2, and 10 is an IMU attitude measurement module. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below in combination with specific embodiments, but the described embodiments are only some of the embodiments of the present application, not all the embodiments.

[0035] Referring to Figure 1 , Figure 2 , Figure 3The embodiment provides an implementation process of a posture-compensated three-dimensional ultrasonic wave wind speed and direction measurement solving method, ultrasonic transducers U1(3) and U2(8) are oppositely installed to form a measurement axis U, ultrasonic transducers V1(7) and V2(4) are oppositely installed to form a measurement axis V, and ultrasonic transducers W1(2) and W2(9) are oppositely installed to form a measurement axis W. The base (5), the support rod (1) and the transducer connecting rod (6) are used for fixing the six ultrasonic transducers in a three-dimensional space according to a specific angle and position relationship, the included angle between the straight line where the three measurement axes U, V and W are located and the plumb direction is 54.74°, the projections of the three measurement axes U, V and W in the horizontal direction are distributed at 120°, and the three measurement axes can be ensured to be orthogonal to each other in space according to the above angle and position relationship. Taking the measurement axis U as an example, the ultrasonic transducer U1(3) transmits ultrasonic waves, the ultrasonic transducer U2(8) receives the ultrasonic waves, and the process is recorded as a forward flow process, and the ultrasonic wave flight time t u1-u2 of the forward flow process can be obtained. u2-u1 The ultrasonic transducer U2(8) transmits ultrasonic waves, the ultrasonic transducer U1(3) receives the ultrasonic waves, and the process is recorded as a reverse flow process, and the ultrasonic wave flight time t v1-v2 of the reverse flow process can be obtained. v2-v1 The ultrasonic transducers V1(7) and V2(4) can obtain the forward flow and reverse flow flight times t w1-w2 and t w2-w1 of the V axis in the same way. The base (5), the support rod (1) and the transducer connecting rod (6) are hollow structures, and the electrical signal lines of the ultrasonic transducers are routed from the inside, and finally the signal lines of the ultrasonic transducers are led out from below the base (5).

[0036] Figure 1 The three mutually orthogonal measurement axes shown in the figure form a measurement axis coordinate system UVW, the X axis of the IMU attitude measurement module is parallel to one of the support rods (1), the Y axis is parallel to one of the transducer connecting rods (6), and the Z axis is vertically upward, and the coordinate system is defined as a carrier coordinate system X0Y0Z0 of the measurement system, the carrier coordinate system of the measurement system is a coordinate system fixedly connected with a mechanical structure base on which the transducer array is installed, the X0 axis and the Y0 axis of the carrier coordinate system are parallel to the base plane, and the Z0 axis is perpendicular to the base plane.

[0037] It is assumed that the carrier of the measurement system is tilted and counterclockwise rotated by 30° around the X0 axis of the carrier coordinate system, and the posture compensation and wind speed and direction solving include the following steps:

[0038] S1: An excitation signal of specific frequency and amplitude is emitted by the ultrasonic transducer excitation device to drive the transmitting transducers of the three measurement axes U, V, and W in the three-dimensional ultrasonic transducer array to emit ultrasonic waves, which are then received by the receiving transducers. The received ultrasonic signals are processed by the ultrasonic signal detection device, and the ultrasonic flight time from emission to reception is recorded. Each measurement axis completes one emission and reception process in both the downstream and upstream directions, resulting in a total of six ultrasonic flight time data points t. u1-u2 , t u2-u1 , t v1-v2 , t v2-v1 , t w1-w2 , t w2-w1 , where t u1-u2 , t u2-u1 The time of flight of the measurement axis U in both downstream and upstream directions is represented by t. v1-v2 , t v2-v1 The time of flight of the measurement axis V in both downstream and upstream directions is represented by t. w1-w2 , t w2-w1 This represents the flight time along and against the current on the measurement axis W, using the U-axis as an example:

[0039] U-axis downstream ultrasonic flight time:

[0040] U-axis counter-current ultrasonic flight time:

[0041] In the formula, L is the distance between the two ultrasonic transducers, c is the propagation speed of the ultrasonic wave, v is the wind speed on the current measurement axis U, and t is the wind speed. u1-u2 For downstream flight time, t u2-u1 This refers to the time spent flying against the current.

[0042] S2: Based on the six ultrasonic flight times t obtained in step S1 u1-u2 , t u2-u1 , t v1-v2 , t v2-v1 , t w1-w2 , t w2-w1 The wind speed components V in the coordinate system of the measurement axes U, V, and W were calculated using the ultrasonic time-of-flight method. u V v V w The calculation formula is as follows:

[0043]

[0044] Where L is the fixed distance between two ultrasonic transducers on each measurement axis;

[0045] S3: Based on the fixed spatial geometric relationship between the U, V, W measurement axis coordinate system and the measurement system carrier coordinate system in the three-dimensional ultrasonic transducer array, first rotate 45° counterclockwise around the W axis, then rotate 54.74° counterclockwise around the U axis to achieve the coincidence of the measurement axis coordinate system UVW and the carrier coordinate system X0Y0Z0. Using a preset coordinate transformation formula, the wind speed component V in the measurement axis coordinate system obtained in step S2 is transformed. u V v V w Wind speed component V converted to the coordinate system of the measurement system x0 V y0 V z0 The conversion formula is as follows:

[0046]

[0047] S4. The three-dimensional ultrasonic anemometer and wind direction measurement system supports both static and dynamic base measurement modes. In static base measurement mode, the measurement system's carrier coordinate system (X0Y0Z0) and the geographic coordinate system (XYZ) must be perfectly aligned during installation, and the measurement system must remain stationary during operation. No attitude compensation is required in this case. x V y V z Values ​​and V x0 V y0 V z0 Completely consistent; In the dynamic base measurement mode, due to the attitude change of the base on which the measurement system is installed, the carrier of the measurement system in this embodiment tilts and rotates counterclockwise by 30° around the X0 axis of the carrier coordinate system. At this time, the X0Y0Z0 coordinate system of the measurement system carrier cannot be aligned with the XYZ coordinate system of the northeast-northeast coordinate system and is in a dynamic change process. Obviously, this embodiment belongs to the dynamic base measurement mode. The attitude Euler angles of the measurement system carrier coordinate system relative to the northeast-northeast coordinate system are output by the IMU attitude measurement module. Constructing a rotation matrix to convert the three-dimensional wind speed components V in the carrier coordinate system in step S3 x0 V y0 V z0 The wind speed vector V in the northeast-sky geographic coordinate system is obtained after attitude compensation. x V y V z To achieve attitude compensation and eliminate errors in the wind speed component, the calculation process is as follows:

[0048]

[0049] S5: Based on the wind speed vector V in the northeast-central geographic coordinate system obtained in step S4 after attitude compensation. x V y Vz Calculate the final wind speed and direction, where:

[0050]

[0051] Wind direction = arctan2(V) x V y )·180 / π+180, the wind direction angle range is defined as 0°~360°.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. For those skilled in the art, the present invention can have various changes and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for calculating three-dimensional ultrasonic wind speed and direction with attitude compensation, characterized in that, This method is based on an ultrasonic transducer array and an IMU attitude measurement module installed according to a specific geometry. The ultrasonic transducer array forms three mutually orthogonal measurement axes U, V, and W, and each measurement axis consists of a pair of ultrasonic transducers. The attitude-compensated three-dimensional ultrasonic wind speed and direction measurement and calculation method includes the following steps S1 to S5: S1: An excitation signal of specific frequency and amplitude is emitted by the ultrasonic transducer excitation device, sequentially driving the transmitting transducers of the three measurement axes U, V, and W in the three-dimensional ultrasonic transducer array to emit ultrasonic waves, which are then received by the receiving transducers. Based on the positive and negative piezoelectric effect, each ultrasonic transducer has both transmitting and receiving functions. The received ultrasonic signals are processed by the ultrasonic signal detection device, and the ultrasonic flight time from emission to reception is recorded. Each measurement axis completes one emission and reception process in both the downstream and upstream directions, obtaining a total of six ultrasonic flight time data points t. u1-u2 , t u2-u1 , t v1-v2 , t v2-v1 , t w1-w2 , t w2-w1 ; S2: Based on the six ultrasonic flight times t obtained in step S1 u1-u2 , t u2-u1 , t v1-v2 , t v2-v1 , t w1-w2 , t w2-w1 The wind speed components V in the coordinate system of the measurement axes U, V, and W were calculated using the ultrasonic time-of-flight method. u V v V w The calculation formula is as follows: Where L is the fixed distance between two ultrasonic transducers on each measurement axis; S3: Based on the fixed spatial geometric relationship between the U, V, and W measurement axes in the three-dimensional ultrasonic transducer array and the coordinate system of the measurement system carrier, the wind speed component V in the measurement axis coordinate system obtained in step S2 is transformed using a preset coordinate transformation formula. u V v V w Wind speed component V converted to the coordinate system of the measurement system x0 V y0 V z0 The coordinate system of the measurement system carrier is a coordinate system fixedly connected to the mechanical structure base on which the transducer array is fixedly installed. Its X0 and Y0 axes are parallel to the base plane, and its Z0 axis is perpendicular to the base plane. The transformation formula is as follows: In x0 =cos(-45°) V u +sin(-45) V v In y0 =(-sin(-45°) V u +cos(-45°) V v )·cos(-54.74°)+sin(-54.74°)·V w ; In z0 =(-sin(-45°) V u +cos(-45°) V v )·(-sin(-54.74°))+cos(-54.74°)·V w S4: The static base measurement mode requires the measurement system to be installed in a fixed position, and the coordinate system of the measurement system carrier must be precisely aligned with the northeast-central geographic coordinate system beforehand. The measurement system must also maintain its attitude during operation. In this mode, the wind speed vector V in the northeast-central geographic coordinate system... x V y V z The wind speed component V in the carrier coordinate system output in step S3 is equal to the wind speed component V. x0 V y0 V z0 : V x =V x0 ;V y =V y0 ;V z =V z0 The dynamic base measurement mode has no special requirements for the installation position and real-time attitude of the measurement system during operation, allowing dynamic changes in the relative attitude between the carrier coordinate system and the northeast-northeast geographic coordinate system. In this mode, real-time attitude compensation is required to eliminate the influence of carrier attitude changes on the measurement results, and the Euler angles of the carrier coordinate system relative to the northeast-northeast geographic coordinate system, measured in real time by the IMU attitude measurement module, are obtained. Based on the attitude Euler angles, a rotation matrix is ​​constructed, and the three-dimensional wind speed component V in the coordinate system of the measurement system carrier obtained in step S3 is... x0 V y0 V z0 Real-time attitude compensation is performed, and the wind speed vector V is converted to the northeast-central geographic coordinate system. x V y V z The conversion formula is as follows: Where φ, θ, These are the angles of rotation sequentially around the Z0, Y0, and X0 axes of the measurement system carrier coordinate system; S5: Based on the wind speed vector V in the northeast-central geographic coordinate system obtained in step S4 after attitude compensation. x V y V z Calculate the final wind speed and direction, where: Wind direction = arctan 2(V) x V y )·180 / π+180, the wind direction angle range is defined as 0°~360°.

2. The method for attitude-compensated three-dimensional ultrasonic wind speed and direction measurement and calculation according to claim 1, characterized in that: The ultrasonic transducer array is installed in three-dimensional space by means of a mounting bracket according to a specific geometric angle and positional relationship. The mounting bracket includes a base (5), a support rod (1) vertically fixed on the base, and a transducer connecting rod (6) for fixing the ultrasonic transducers. The mounting bracket has a hollow cavity structure inside, and all electrical signal lines of the ultrasonic transducers are laid inside the hollow cavity and finally led out from the bottom of the base (5). The ultrasonic transducers are respectively installed at the ends of the transducer connecting rods. Every two ultrasonic transducers are installed opposite each other to form a measuring axis, thus forming three measuring axes: U, V, and W. Each measuring axis makes an angle of 54.74° with the vertical direction, and the projections of the three measuring axes in the horizontal direction are 120° apart, so that the three measuring axes U, V, and W are orthogonal to each other in three-dimensional space, satisfying the coordinate transformation formula described in step S3: The IMU attitude measurement module is fixedly installed in the central area of ​​the base (5), with its coordinate axes aligned with the coordinate system of the measurement system carrier. It measures the attitude information of the carrier coordinate system relative to the northeast-northeast coordinate system in real time. The integrated processor inside the module automatically calculates and outputs the attitude Euler angles of the carrier coordinate system relative to the northeast-northeast coordinate system in Euler angle form. Where φ is the heading angle and θ is the pitch angle. This refers to the roll angle.

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