Unmanned aerial vehicle attitude perception-based base station antenna directional diagram measuring device and method

Abstract

The application discloses a base station antenna directional diagram measuring device and method based on unmanned aerial vehicle attitude sensing, and belongs to the technical field of wireless communication and antenna testing. The device comprises an unmanned aerial vehicle platform, a central processing module and a signal receiving and storing module. The unmanned aerial vehicle platform is provided with a three-dimensional holder and sensing equipment. The sensing equipment comprises an RTK-GPS, an IMU and an electronic compass. At each measuring point, the deviation between the current angle and the expected angle of the holder is calculated in real time and taken as the input of a controller to generate a holder driving instruction and realize closed-loop control. The pose information of each measuring point is recorded, and the base station signal is received at each measuring point and the original signal is recorded and stored to generate the base station antenna directional diagram. The application realizes high-precision and automatic measurement of the base station antenna directional diagram and can accurately restore the actual performance of the antenna in the network.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication and antenna testing, in particular to a base station antenna directional diagram measuring device and method based on unmanned aerial vehicle attitude sensing. BACKGROUND

[0002] Traditional manual or ground measurement methods cannot accurately determine the relative position and attitude of the measurement antenna and the base station antenna to be measured, resulting in large alignment errors and measurement results that cannot truly reflect the in-network directional diagram of the antenna.

[0003] Complex operation and low efficiency: the traditional method requires a large amount of manual intervention and repeated calibration at multiple measurement points, which is tedious and time-consuming, especially in complex terrain such as rooftops and mountainous areas.

[0004] Dynamic disturbance has a large impact: when using an unmanned aerial vehicle as a platform, wind disturbance and body vibration during flight can cause the attitude of the unmanned aerial vehicle to change constantly, and if not compensated in real time, the pointing of the measurement antenna will continuously deviate from the target, resulting in distorted measurement data.

[0005] High risk of high-altitude operation: in the traditional method, some scenarios require manual tower climbing or high-altitude operation, which poses a high safety risk. SUMMARY

[0006] The present application aims to overcome the shortcomings of the prior art and provide a base station antenna directional diagram measuring device and method based on unmanned aerial vehicle attitude sensing.

[0007] The purpose of the present application is achieved by the following technical solution: a base station antenna directional diagram measuring device based on unmanned aerial vehicle attitude sensing, comprising:

[0008] An unmanned aerial vehicle platform carries a three-dimensional gimbal and a sensing device, and performs a flight path task; the three-dimensional gimbal carries a measurement antenna for receiving measurement signals during flight path operation, and the three-dimensional gimbal adjusts the azimuth and elevation angles according to gimbal driving instructions from a central processing module; the sensing device is used to accurately obtain the position and attitude of the unmanned aerial vehicle in three-dimensional space;

[0009] A central processing module uses an embedded computer for real-time data fusion, target vector calculation, gimbal driving instruction generation, and sending of gimbal driving instructions to the three-dimensional gimbal to adjust the azimuth and elevation angles;

[0010] A signal receiving and storing module is used to record and store the signals received by the measurement antenna to generate a base station antenna directional diagram.

[0011] A base station antenna directional diagram measuring method based on unmanned aerial vehicle attitude sensing, comprising the following steps:

[0012] Step S1. Establish a local ENU coordinate system with the base station as the origin, and convert the UAV RTK coordinates to the position in the ENU coordinate system in real time ;

[0013] Step S2. Take the actual phase center of the measurement antenna as the transmission point, and calculate the unit vector pointing to the base station in the ENU coordinate system, i.e. the target direction in ENU ;

[0014] Step S3. Convert the target direction in ENU to the body coordinate system FRD;

[0015] Step S4. Convert to two degrees of freedom of the gimbal, i.e. azimuth and elevation, and take the obtained azimuth and elevation as the expected angles of the gimbal;

[0016] Step S5. At each measurement point, calculate the deviation between the current angle of the gimbal and the expected angle in real time, generate the gimbal driving instructions, and realize closed-loop control;

[0017] Step S6. Record the pose information (i.e. the information output by RTK-GPS, IMU and electronic compass) of each measurement point, and receive the base station signal at each measurement point and store the original signal record, so as to generate the base station antenna directional diagram.

[0018] The beneficial effects of the present application are: extremely high alignment accuracy: by combining high-precision GPS / IMU data and active gimbal compensation algorithm, the influence of UAV attitude jitter on measurement accuracy is eliminated, and "pixel-level" alignment of the measurement antenna to the base station antenna is realized, and the measurement result is highly reliable.

[0019] Full automation and high efficiency: (1) Measurement process automation, only need to preset the flight route and base station information, can automatically complete the scanning measurement in all directions or specific angles, greatly improves the measurement efficiency, and the single station measurement time can be shortened from several hours to several tens of minutes.

[0020] (2) Realize the "restoration" of antenna performance: due to high measurement accuracy, the obtained data can accurately draw the directional diagram of the antenna in the actual installation environment, so as to "restore" its real coverage performance, and provide irrefutable data support for network optimization and fault diagnosis (such as antenna skew, reverse feeder connection, etc.).

[0021] (3) Strong safety and accessibility: no need for manual tower climbing, avoiding the risk of high-altitude operation, and some base stations that are difficult to reach by traditional methods can be easily measured, with wide application range. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 A method flowchart of the present application. DETAILED DESCRIPTION

[0023] The technical solutions of the present application are described in further detail below in conjunction with the accompanying drawings, but the scope of protection of the present application is not limited to the following description.

[0024] The base station antenna pattern measurement device based on unmanned aerial vehicle attitude perception comprises:

[0025] An unmanned aerial vehicle platform carries a three-dimensional gimbal and a sensing device, and performs a flight path task; the three-dimensional gimbal carries a measurement antenna for receiving measurement signals during flight path flight, and the three-dimensional gimbal is used to adjust the azimuth angle and the pitch angle according to gimbal driving instructions from a central processing module; the sensing device is used to obtain the position and attitude of the unmanned aerial vehicle in three-dimensional space with high precision;

[0026] The central processing module adopts an embedded computer for real-time data fusion, target vector calculation, gimbal driving instruction generation, and sending of gimbal driving instructions to the three-dimensional gimbal for adjustment of the azimuth angle and the pitch angle;

[0027] The signal receiving and storing module is used to record and store the signals received by the measurement antenna, so as to generate a base station antenna pattern.

[0028] The sensing device comprises an RTK-GPS, an IMU, and an electronic compass;

[0029] The sensing device comprises an RTK-GPS, an IMU, and an electronic compass;

[0030] The RTK-GPS is used to obtain the positioning information of the unmanned aerial vehicle in three-dimensional space, including longitude, latitude, and height;

[0031] The IMU is used to provide the quaternion of the attitude information of the unmanned aerial vehicle and the angular velocity of the body;

[0032] The electronic compass is used to provide the heading angle of the unmanned aerial vehicle.

[0033] As shown in the figure, the base station antenna pattern measurement method based on unmanned aerial vehicle attitude perception comprises the following steps: Figure 1

[0034] Step S1. Establish a local ENU coordinate system with the base station as the origin, and convert the RTK coordinates of the unmanned aerial vehicle to the position in the ENU coordinate system in real time ;

[0035] S101. Given the base station geodetic coordinates: , and the RTK geodetic coordinates of the unmanned aerial vehicle: ; wherein,​ respectively represent the longitude, latitude and elliptic height of the base station, respectively represent the longitude, latitude and elliptic height of the unmanned aerial vehicle;

[0036] At a given latitude The calculation formula of the radius of curvature of the prime vertical circle is

[0037]

[0038] wherein, is the length of the major axis of the earth, in meters; represents the square of the first eccentricity, , represents the flattening of the earth as an ellipsoid, ;

[0039] S102. The conversion formula of the base station geodetic coordinate system and the unmanned aerial vehicle RTK geodetic coordinate system to the ECEF coordinate system is:

[0040]

[0041] is the coordinate obtained by conversion to the ECEF coordinate system; the ECEF coordinate system refers to the Earth-Centered Earth-Fixed rectangular coordinate system;

[0042] When is taken , the obtained is the conversion result of the base station geodetic coordinate system to the ECEF coordinate system, denoted as =( , );

[0043] When is taken , the obtained is the conversion result of the unmanned aerial vehicle RTK geodetic coordinate system to the ECEF coordinate system, denoted as ;

[0044] S103. Convert the ECEF coordinate system to the local ENU coordinate system:

[0045] Calculate the relative displacement of the unmanned aerial vehicle and the base station in the ECEF coordinate system :

[0046]

[0047] The rotation matrix of the ENU coordinate system with the base station as the origin to the ENU coordinate system is:

[0048] ​

[0049] Calculate the position of the UAV in the ENU coordinate system with the base station as the origin :

[0050] .

[0051] Step S2. Take the measured antenna actual phase center as the transmitting point, and calculate the unit vector pointing to the base station in the ENU coordinate system, i.e. the target direction in ENU ;

[0052] S201. Given the operator that converts the ENU coordinate system to the NED coordinate system :

[0053]

[0054] S202. Construct the rotation matrix of the NED coordinate system to the body coordinate system FRD from the UAV attitude quaternion :

[0055]

[0056] Calculate the rotation matrix of the ENU coordinate system to the body coordinate system FRD:

[0057]

[0058] S203. Calculate the rotation matrix of the body coordinate system FRD to ENU:

[0059]

[0060] S204. Calculate the measured antenna position:

[0061] Let the fixed offset of the RTK antenna relative to the measured antenna in the FRD coordinate system be , and convert it to the offset in the ENU coordinate system :

[0062]

[0063] Calculate the phase center position of the measured antenna :

[0064]

[0065] S205. Calculate the unit vector of the phase center of the measured antenna pointing to the base station, i.e. the target direction:

[0066] ​​

[0067] wherein, is the negation result of

[0068] .

[0069] Step S3. Convert the target direction under ENU to the body coordinate system FRD;

[0070] Send the target direction into the body coordinate system to get the target direction that needs to be pointed in the body-centered coordinate system :

[0071] .

[0072] This step naturally offsets the pitch / roll / yaw of the body, so that the gimbal control only needs to face the target direction in the "machine body view".

[0073] Step S4. Convert to two degrees of freedom of the gimbal, i.e. azimuth and pitch, and take the obtained azimuth and pitch as the expected angle of the gimbal;

[0074] Calculate the azimuth :

[0075] The azimuth is the right turn angle relative to "machine head straight ahead" on the horizontal plane; atan2 automatically handles the quadrant;

[0076] Calculate the pitch :

[0077] .

[0078] wherein, Down of FRD coordinate system is positive, and the pitch angle "up is positive", so take .

[0079] In the embodiments of the present application, when , the azimuth value is unstable, and is locked as the last valid value, and only the pitch is controlled; if the gimbal coordinate definition is different from FRD, take the negative of the pitch or handle it in the installation calibration matrix.

[0080] Step S5. At each measurement point, calculate the deviation of the current angle of the gimbal from the expected angle in real time, generate a gimbal driving instruction, and realize closed-loop control;

[0081] S501. Error calculation and controller input: calculate the deviation of the current angle of the gimbal from the expected angle in real time as the input of the controller, and support stable tracking:

[0082] Get the expected gimbal angle, including:

[0083] desired azimuth angle , desired pitch angle = , unit: degree or radian;

[0084] get gimbal feedback, including current actual azimuth angle , and current actual pitch angle , which are obtained by real-time acquisition of gimbal feedback;

[0085] get attitude data: body angular velocity , which is obtained from IMU, , unit: rad / s;

[0086] error solving: azimuth error ; pitch error ;

[0087] In the embodiments of the present application, limiting processing is needed: limit the error to [-180°, 180°] to avoid wrap-around, if |error|>threshold, trigger alarm log;

[0088] S502. The central processor generates gimbal driving instructions to realize closed-loop stabilization and dynamic compensation:

[0089] In the embodiments of the present application, input preparation: package error and angular velocity, send to controller, every 10-20ms cycle, match main loop frequency; Wherein the controller refers to the algorithm module of the gimbal tracking control loop integrated in the central processor, including (PID or PI controller with angle error as input) and feedforward module (prediction compensation based on body angular velocity / angular acceleration)

[0090] For azimuth angle:

[0091] send the azimuth error to the first PID controller, and output a control signal from the first PID controller ;

[0092] calculate the feedforward compensation control signal of the azimuth angle: ; is a pre-calibration matrix; the feedforward azimuth compensation is based on ;

[0093] calculate the total control output of the azimuth angle:

[0094] use to generate gimbal driving instructions to drive and control the gimbal;

[0095] For pitch angle:

[0096] The pitch error is sent to a second PID controller, and a control signal is output by the second PID controller ;

[0097] A feedforward compensation control signal of the pitch angle is calculated: ; the feedforward pitch compensation is based on ;

[0098] A total control output of the pitch angle is calculated:

[0099] The gimbal driving instruction is generated, and the gimbal is driven and controlled.

[0100] In the embodiments of the present application, the PID calculation mode is: , which is independently calculated for the azimuth and the pitch, respectively; Kp / Ki / Kd needs to be tuned, and the initial value is based on the gimbal specification; wherein is the deviation of the expected angle and the actual angle (when e takes the azimuth error , then If e takes the pitch error , then ), The initial value is set according to the gimbal specification (inertia, rated motor torque), and is iteratively tuned in actual tests.

[0101] In the embodiments of the present application, frequency stratification is performed: the outer loop runs at 50-200 Hz in this step; the inner loop is built-in ≥500 Hz in the gimbal driver, to ensure high-frequency response;

[0102] In the embodiments of the present application, the system first compares the expected gimbal angle with the actual feedback angle to obtain the errors in the azimuth and the pitch directions. Subsequently, the control module performs operation based on the errors to generate the driving instruction for the motor, and the control method is divided into two parts: PID control: through the proportional, integral and differential links, the instantaneous error is suppressed, the accumulated deviation is eliminated, and the dynamic oscillation is reduced, so as to realize basic tracking of the expected angle.

[0103] Feedforward compensation: the body angular velocity information is introduced at the same time, the offset caused by the disturbance of the unmanned aerial vehicle attitude is predicted in advance, and a compensation amount is added to the control instruction, so as to accelerate the response speed and improve the stability.

[0104] Finally, the PID output and the feedforward compensation are superimposed to form the total gimbal driving instruction, and are limited in amplitude when necessary to avoid motor overload. The whole process is run by the upper computer at a medium frequency, and the internal gimbal completes fine adjustment through a high-speed current / speed loop. This layered closed-loop control ensures dynamic response and stability.

[0105] ​In the embodiments of the present application, performance optimization can also be performed: monitor error convergence time; if jitter is large, increase Kalman filter smoothing , or adjust PID parameters adaptively;

[0106] Integration suggestion: implement algorithms using embedded computers, support ROS node publishing / subscription; record control data;

[0107] Safety mechanism: if RTK / IMU signal is lost, switch to open-loop mode, fix gimbal angle; degrade alarm when frequency < 50 Hz;

[0108] Test indicators: static tracking error < 0.5°, dynamic tracking error < 1° (dynamic); response delay < 20 ms.

[0109] During system operation, control effect needs to be continuously optimized and monitored. The specific process includes:

[0110] Performance observation: real-time monitoring of angle error and response process, if oscillation or slow convergence occurs, control parameters can be adjusted or filtering can be added to improve.

[0111] Data integration: all control quantities and error data are recorded and stored for subsequent analysis and parameter optimization.

[0112] Safety mechanism: once sensor data interruption or main control frequency anomaly is detected, the system will immediately switch to safety mode, keeping the gimbal at a stable angle to avoid the risk of losing control.

[0113] Through the above optimization and monitoring, the present scheme can maintain stable work under actual flight disturbance and complex environment, and enter safety mode in time when an exception occurs, thereby ensuring the reliability of measurement data and the safety of system operation.

[0114] Step S6. Record the pose information (i.e. the information output by RTK-GPS, IMU and electronic compass) of each measurement point, and receive the base station signal at each measurement point and record and store the original signal, so as to generate a base station antenna directional diagram.

[0115] The above description shows and describes one preferred embodiment of the present application, but as previously mentioned, it should be understood that the present application is not limited to the form disclosed herein, should not be considered as excluding other embodiments, and can be used in various other combinations, modifications and environments, and can be modified within the scope of the inventive concept described herein, by the above teachings or related art or knowledge. Any modification and change made by those skilled in the art without departing from the spirit and scope of the present application shall be within the protection scope of the appended claims of the present application.

Claims

1. A method for measuring a base station antenna directional diagram based on an unmanned aerial vehicle (UAV) attitude perception, characterized in that: The method comprises the following steps: Step S1. Establish a local ENU coordinate system with the base station as the origin, and convert the UAV RTK coordinates to the position in the ENU coordinate system in real time ; Step S2. Take the measured antenna actual phase center as the transmitting point, and calculate the unit vector pointing to the base station in the ENU coordinate system, i.e. the target direction in ENU ; Step S3. The target direction under the ENU is obtained Turning to the body coordinate system FRD, the target direction to be pointed to under the body-centered coordinate system is obtained ; Step S4. Convert the yaw angle and the pitch angle to two degrees of freedom of the gimbal, i.e. azimuth angle and elevation angle, and take the obtained azimuth angle and elevation angle as the expected angles of the gimbal. Convert the yaw angle and the pitch angle to two degrees of freedom of the gimbal, i.e. azimuth angle and elevation angle, and take the obtained azimuth angle and elevation angle as the expected angles of the gimbal. Step S5. At each measurement point, the deviation of the current angle of the gimbal from the expected angle is calculated in real time to generate a gimbal driving instruction and realize closed-loop control. Step S6. The pose information of each measurement point is recorded, i.e. the information output by the RTK-GPS, the IMU and the electronic compass, and the raw signal is recorded and stored at each measurement point to facilitate the generation of the base station antenna directional diagram.

2. The method of claim 1, wherein the method further comprises: The step S1 comprises: S101. Given the base station geodetic coordinates: , and the UAV RTK geodetic coordinates: ; wherein, respectively represent the longitude, latitude and ellipsoidal height of the base station, respectively represent the longitude, latitude and ellipsoidal height of the UAV; At a given latitude The calculation formula of the curvature radius of the prime vertical is determined as follows The calculation formula of the curvature radius of the prime vertical is determined as follows ； wherein is the length of the major axis of the Earth, in meters; denotes the first eccentricity squared, , denotes the flattening of the Earth as an ellipsoid, ; S102. The conversion formula of the base station geodetic coordinate system and the unmanned aerial vehicle RTK geodetic coordinate system to the ECEF coordinate system is given: ； refers to coordinates obtained by converting to the ECEF coordinate system; the ECEF coordinate system refers to the Earth-Centered, Earth-Fixed rectangular coordinate system; When Take , the resulting is the conversion result of the base station geodetic coordinate system to the ECEF coordinate system, denoted as =( , ); When Take , get The conversion result of the UAV RTK geodetic coordinate system to the ECEF coordinate system is recorded as ; S103. The ECEF coordinate system is converted to the local ENU coordinate system: Computing relative displacement of a drone and a base station in an ECEF coordinate system : ； The rotation matrix of the body frame to the ENU coordinate system with the base station as the origin is: ； calculating the position of the drone in an ENU coordinate system with the base station as the origin : 。 3.The method of claim 1, wherein: The step S2 comprises: S201. Given an operator that converts ENU coordinate system to NED coordinate system : ； S202. Construct a rotation matrix of the NED coordinate system to the body coordinate system FRD from the drone attitude quaternion :​ ； The rotation matrix of the ENU coordinate system to the body coordinate system FRD is calculated: ； S203. The rotation matrix of the body coordinate system FRD to the ENU is calculated: ； S204. The measurement antenna position is calculated: Under the system FRD, the fixed offset of RTK antenna relative to the survey antenna , which is converted into the offset in the ENU coordinate system : ； Computing a phase center position of a measuring antenna : ； S205. Calculate the unit vector of the phase center of the measuring antenna pointing to the base station, with the base station as the origin i.e. the target direction: ； wherein is the negated result of 。 4. The method of claim 3, wherein the method further comprises: The step S3 comprises: Send the target direction into the body coordinate system, get the target direction that needs to point to in the body-centered coordinate system : 。 5. The method of claim 4, wherein: The step S4 comprises: Computing an azimuth angle : ; The azimuth angle is the right turning angle on the horizontal plane relative to the "head straight ahead"; the atan2 automatically processes the quadrant; Computing the pitch angle : 。 6. The method of claim 5, wherein the method further comprises: The step S5 comprises: S501. Error calculation and controller input: the deviation of the current angle of the gimbal from the expected angle is calculated in real time as the input of the controller to support stable tracking: The expected gimbal angle is obtained, comprising: desired azimuth angle , desired elevation angle = , in degrees or radians; Obtaining gimbal feedback, including a current actual azimuth angle , and a current actual pitch angle , are obtained by real-time acquisition of gimbal feedback; Acquisition of attitude data: body angular velocity This data is acquired from the IMU, in rad / s; Error solution: azimuth error ; pitch error ; S502. The central processing unit generates a gimbal driving instruction to realize closed-loop stability and dynamic compensation: For the azimuth angle: The azimuth error is sent into a first PID controller, and a control signal is outputted by the first PID controller ; feedforward compensation control signal for the azimuth angle: ; is a pre-calibration matrix; the feedforward azimuth compensation is based on ; Total control output for calculating azimuth angle: ; Utilizing Generate a gimbal driving instruction to drive and control the gimbal. For the pitch angle: The pitch error is sent to a second PID controller, and a control signal is outputted by the second PID controller ; A feedforward compensation control signal for the pitch angle is calculated: ; the feedforward pitch compensation is based on ; Total control output for calculating the pitch angle: ; Utilizing Generate a gimbal driving instruction to drive and control the gimbal.

7. The base station antenna directional diagram measurement device based on the unmanned aerial vehicle attitude sensing, adopts the method in any one of claims 1-6, characterized in that: Comprising: An unmanned aerial vehicle platform, carrying a three-dimensional gimbal and a sensing device, and performing a route flight task; the three-dimensional gimbal carries a measurement antenna, which is used for receiving measurement signals during the route flight process; the three-dimensional gimbal is used for adjusting the azimuth angle and the pitch angle according to the gimbal driving instruction received from the central processing module; the sensing device is used for obtaining the position and attitude of the unmanned aerial vehicle in the three-dimensional space with high precision; A central processing module, which is an embedded computer, is used for real-time data fusion, target vector calculation, gimbal driving instruction generation, and sending the gimbal driving instruction to the three-dimensional gimbal to adjust the azimuth angle and the pitch angle; A signal receiving and storing module is used for recording and storing the signals received by the measurement antenna to facilitate the generation of the base station antenna directional diagram.

8. The unmanned aerial vehicle attitude-sensing-based base station antenna directional diagram measurement device according to claim 7, characterized in that: The sensing device comprises an RTK-GPS, an IMU and an electronic compass; The RTK-GPS is used for obtaining the positioning information of the unmanned aerial vehicle in the three-dimensional space, including the longitude, the latitude and the height; The IMU is used for providing the quaternion of the attitude information of the unmanned aerial vehicle and the angular velocity of the body; The electronic compass is used for providing the heading angle of the unmanned aerial vehicle.

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