Correction method of theodolite measurement data without grounding based on orthogonal level sensor

Abstract

The method for correcting theodolite measurement data without landing based on orthogonal horizontal sensors relates to the field of photoelectric theodolite measurement technology. It solves the problems in the prior art that the sensor installation process is complicated and costly, and that model errors are introduced without considering the angle sensor errors. The method installs two orthogonal sensors on the base of the device, and sends their respective horizontal tilt angles to the real-time data processing end through the serial port in real time. The real-time data processing end adopts the method of coordinate rotation, directly uses the original measurement data of the sensor, and converts the measurement data of the device coordinate system into the real measurement data under the site horizontal coordinate system, thereby ensuring the accurate ballistic measurement of the device when the vehicle is roughly leveled. The present invention can perform precise ballistic measurement through real-time data correction processing.

Description

Technical Field

[0001] The invention relates to the technical field of photoelectric theodolite measurement, and in particular to a method for correcting measurement data of a photoelectric theodolite without touching the ground based on an orthogonal level sensor. Background Art

[0002] The photoelectric theodolite is an important part of the ballistic aerospace measurement system. It can record the flight attitude of the target and measure the target's ballistic data with high precision by acquiring the optical image of the target and processing the data. It is one of the most effective measurement equipment for evaluating the tactical strike effect of missiles and the attitude of precise aircraft in modern shooting ranges. With the gradual improvement of the requirements for the mobility of optical measurement equipment in modern shooting ranges, the photoelectric theodolite must have the ability to quickly deploy stations and network, and vehicle-mounted non-ground measurement has gradually become a common working mode of mobile equipment.

[0003] When the vehicle-mounted photoelectric theodolite is performing non-ground measurement, the reference plane is leveled through the automatic leveling system. During the process, elastic links such as tires are detached to minimize the impact of unstable links on the measurement. However, due to interference from foundation stability, wind speed, generators, thermal deformation, etc., the inclination angle of the reference plane leveled each time is different from the maximum inclination direction, and the inclination angle is also large, generally from a dozen seconds to dozens of seconds. If this inclination is not measured and compensated, the photoelectric theodolite cannot achieve precise ballistic measurement.

[0004] There are currently many related solutions for methods of correcting measurement data of vehicle-mounted photoelectric theodolites.

[0005] The document "Correction of Angle Measurement Errors of the Reference Plane of a Vehicle-mounted Photoelectric Theodolite" uses the measured angle data of two mutually perpendicular horizontal sensors to derive the calculation formula for calculating the inclination angle and maximum inclination direction of the entire reference plane based on the inclination angle measured by the horizontal sensor. Finally, the spherical coordinate system is used to analyze the angle measurement error caused by the reference plane error and a correction formula is given. The correction model of this method is to correct the measurement data based on the inclination angle and maximum inclination direction. Therefore, the original measurement angle of the horizontal sensor must be converted into the inclination angle and azimuth of the reference plane. During the conversion process, the model uses approximate processing, which introduces model errors.

[0006] The document "Real-time Error Correction Method for Non-ground Measurement of Vehicle-mounted Photoelectric Theodolite" measures the tilt angle of the equipment base with a high-precision optical angle measurement method based on double grating interference to generate moiré fringes to measure the torsion angle. In the subsequent data processing, the original measured angle data is used to correct the measured data through the idea of ​​coordinate rotation. Although this method has no model error, the high-precision angle measurement equipment required for the optical measurement equipment is complex in structure and high in cost, which is not conducive to subsequent maintenance.

[0007] Patent CN106767678A provides a method of calculating the inclination angle of the base of the device by using a laser and a fixed mirror group installed on the base of the theodolite by detecting the reflected laser. The device is divided into two parts: a fixed part and a mobile part. Although the measurement accuracy is high, the overall structure is complex and not conducive to installation and debugging. At the same time, the patent does not provide a specific error compensation algorithm. The document "Selection and Installation of Inclination Measuring Devices for Vehicle-mounted Theodolites" uses the finite element method to analyze the deformation of the vertical axis of the photoelectric theodolite, and concludes that installing the inclination sensor at the bottom of the vertical axis is conducive to improving the accuracy of non-ground measurement data, but does not analyze how to use the inclination sensor data to compensate for the measurement data in the future.

[0008] The existing method for correcting the measurement data of vehicle-mounted optical measurement equipment without landing uses a relatively complex inclination sensor or method, which places great demands on the installation, adjustment, use and maintenance of the mechanical device. In addition, the high cost is not conducive to mass production, and the use process is relatively cumbersome. Most of the algorithms for subsequent data correction start from the vertical axis tilt angle of the correction device. It is necessary to convert the original measurement data of the sensor into the vertical axis tilt angle and tilt direction of the device base through a model, and then perform the final measurement data correction based on the model for correcting the vertical axis tilt. The above-mentioned model derivation involves the use of approximate quantities, and the model error has been introduced without considering the angle sensor error.

[0009] Although the model error has little effect on the final result within a small angle range, in order to further improve the equipment measurement data correction capability, the present invention provides a correction method using the original measurement data of the sensor. At the same time, the horizontal sensor required by the present invention is low in cost, simpler and more convenient in installation and use, greatly saving manufacturing costs, subsequent maintenance costs and operator training costs, and the sensor can be directly installed on the vehicle-mounted photoelectric theodolite in the field. Summary of the invention

[0010] The present invention aims to solve the problems in the prior art that the sensor installation process is complicated and costly, and model errors are introduced without considering the angle sensor errors. A method for correcting measurement data of a theodolite without touching the ground based on an orthogonal horizontal sensor is provided.

[0011] A method for correcting theodolite measurement data without touching the ground based on an orthogonal level sensor is implemented by the following steps:

[0012] Step 1: During the first calibration, when the theodolite is leveled, clear the angle output by the orthogonal level sensor;

[0013] Step 2: Use the coordinate rotation method to correct the measurement data; first, determine the rotation angle. According to the actual physical meaning of the output angle of the orthogonal horizontal sensor, the angle of the second coordinate rotation is related to the angle α of the first coordinate rotation. Therefore, the second rotation angle β′ is the result after the β angle is corrected. The initial angle θ is the angle between the X-axis of the sensor coordinate system and the geodetic north. The initial angle θ can be determined by iteration.

[0014] Step 3: Complete the correction of the equipment measurement data; that is, convert the measurement angle under the equipment measurement coordinate system into the measurement data under the site horizontal coordinate system as the final measurement result.

[0015] Beneficial effects of the present invention: The method for correcting the measurement data of the theodolite without touching the ground based on the orthogonal horizontal sensor of the present invention requires that two orthogonal sensors be installed on the base of the device, and the respective horizontal tilt angles are sent to the real-time data processing end in real time through the serial port. The real-time data processing end adopts the idea of ​​coordinate rotation, directly uses the original measurement data of the sensor, and converts the measurement data of the device coordinate system into the real measurement data under the site horizontal coordinate system, thereby ensuring the accurate trajectory measurement of the device when the vehicle is roughly leveled.

[0016] The present invention utilizes the equipment base inclination angle output by two mutually orthogonal level sensors to perform real-time correction on the equipment's measurement data, giving full play to the mobility of the vehicle-mounted equipment and achieving the ability to perform precise ballistic measurement by only roughly leveling the vehicle and through real-time data correction processing.

[0017] The inclination sensor of the present invention is easy to install, does not require special processing and adjustment, does not need calibration in the installation workshop, and can be retrofitted to external field equipment.

[0018] In the present invention, the data correction method starts from the perspective of coordinate rotation, carefully analyzes the physical meaning represented by each measured angle, and compensates and corrects the angle β of the second horizontal sensor to make it meet the actual angle during coordinate rotation. At the same time, the angle compensation correction has no approximate processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of an orthogonal level sensor installed on a base of the device in the method for correcting measurement data of the theodolite without falling to the ground based on the orthogonal level sensor of the present invention;

[0020] Figure 2Schematic diagram of coordinate conversion relationship; (a) is a schematic diagram of the projection of the angle θ between the horizontal sensor axis and the geodetic north on the XOZ plane; (b) is a three-dimensional schematic diagram of the angle θ between the horizontal sensor axis and the geodetic north; (c) is a schematic diagram of the inclination angles α and β of the two axes of the horizontal plane of the photoelectric theodolite in the orthogonal horizontal sensor coordinate system; (d) is a schematic diagram of the angle of the theodolite coordinate system relative to the site horizontal coordinate system; DETAILED DESCRIPTION

[0021] Combination Figure 1 and Figure 2 The present embodiment is described as follows: a method for correcting theodolite measurement data without touching the ground based on an orthogonal level sensor. The method is implemented by the following steps:

[0022] 1. Sensor installation;

[0023] When correcting the equipment measurement data, how to install the tilt sensor is crucial. The installation position and sensor type directly affect the subsequent correction algorithm. The two level sensors in this embodiment are independent of each other but installed orthogonally. Each sensor can measure the angle of its own posture relative to the horizontal plane.

[0024] In this embodiment, an orthogonal level sensor is installed on the base of the device, such as Figure 1 As shown, the two horizontal sensors are A and B. The orthogonality of the two horizontal sensors is ensured by mechanical precision processing when the inclinometer is designed. When the inclinometer is installed on the base of the photoelectric theodolite, there are no many requirements for installation and adjustment. A direct rigid connection is sufficient. The data on each axis will be zero-calibrated later.

[0025] 2. Sensor level reset;

[0026] Since the orthogonal horizontal inclinometers are not cleared to zero when they are installed, the angle output by the inclinometers may not be zero when the base of the equipment is horizontal. It is difficult to ensure that the base of the equipment and the two inclinometers are completely horizontal during installation, which increases the requirements for the installer. In this solution, the zero position between the two sensors and the base can be cleared through the back-end real-time processing software. The specific method is as follows: After the vehicle is leveled, the base is manually adjusted to the level using an electronic level. Each photoelectric theodolite base has three leveling legs to achieve this function. After the photoelectric theodolite base is level, the real-time data processing software records the output angles of the two sensors and sets the angles as the zero position values ​​of each sensor. After the base of the subsequent equipment is tilted, the angles decomposed into the two inclinometer axes are the changes relative to their respective zero position values. At the same time, the zero position value is a fixed value, and there is no need to re-measure after each change of the site.

[0027] 3. Coordinate rotation; Figure 2 shown.

[0028] In this embodiment, when correcting the measurement data, the coordinate rotation method is used, that is, the measurement data in the measurement coordinate system of the inclined base is rotated to the site horizontal coordinate system. The relationship between the two coordinate systems is shown in Figure (d).

[0029] First, analyze the horizontal coordinate system (X N ,Y N ,Z N ) to the device measurement coordinate system (X B ,Y B ,Z B ) needs to be rotated. Since the inclination of the base of the photoelectric theodolite is measured by an orthogonal horizontal sensor, the coordinate system (X S ,Y S ,Z S ) is used as the intermediate coordinate system, which is referred to as the sensor coordinate system in this patent.

[0030] Due to the mobility of the vehicle-mounted equipment, it is impossible to guarantee that every time you arrive at the task point, as shown in Figure (a), this implementation is called the initial angle θ. This angle needs to be recalculated every time the vehicle-mounted equipment changes its position. In this implementation, the calculation method of the angle θ and the quick solution method after changing the station site will be given later.

[0031] First, the site horizontal coordinate system is rotated around Y N The axis rotates θ and transforms from the site horizontal coordinate system to the sensor coordinate system. In the sensor coordinate system, the orthogonal horizontal sensor can measure the angular deviations α and β between the two axes of the photoelectric theodolite and the horizontal plane, where α is the X S The angle of axis tilt, β is Z S The angle of inclination of the axis is shown in Figure (c). S The axis rotates α, and then the X B′ After the axis is rotated by β′, the plane X B′ -OZ B′ The plane where the theodolite base is located. Since the equipment vehicle was calibrated using differential GPS after leveling, the X-axis of the measurement coordinate system and the site horizontal coordinate system both point to the north of the earth, so the last step is to go around the Y B′ Rotate -θ, and finally get the device measurement coordinate system (X B ,Y B ,Z B ), as shown in Figure (d).

[0032] In the above coordinate transformation, it can be seen that by rotating around Z S The axis rotates α, and then the X B′The shaft rotates β′, and the angle β′ of the second rotation is related to the angle α of the first rotation. The β measured by the sensor cannot be used directly, and the second rotation angle β′ needs to be calculated.

[0033] The derivation of β′ is as follows: S The axis rotates α, and then the X B′ The effect of the rotation β′ about the X axis is similar to that of S The axis rotates β, and then the Z axis of the rotated coordinate system B′ The effect of axis rotation α′ is the same, so the final rotation matrix results of the two rotation methods are the same:

[0034]

[0035] After simplification, we get:

[0036]

[0037] Finally, we can deduce:

[0038] The above describes the process of rotating the site horizontal coordinate system four times and converting it into the measurement coordinate system. The data correction of the photoelectric theodolite is to convert the target orientation A in the measurement coordinate system B 、Pitch E B , converted to the target orientation A in the station horizontal coordinate system N 、Pitch E N , the conversion formula is as follows:

[0039]

[0040]

[0041]

[0042] The angle symbol in the formula needs to satisfy:

[0043] a. The signs of the angles in the matrix satisfy the right-hand rule;

[0044] b. The output angle of two orthogonal horizontal angle sensors is positive when they are farther away from the device.

[0045] 4. Determination of the initial angle θ;

[0046] The angle θ can be determined by calibration in the installation workshop. When the equipment changes its site, the angle θ needs to be re-determined. After the equipment is moved to a new location, the azimuth encoder 0-degree point calibration should be performed according to the differential GPS or azimuth mark, so that the azimuth encoder output value is 0 degrees when the equipment points to due north. Therefore, the angle difference that the azimuth encoder needs to correct for the north can be used to superimpose the difference on the previous θ angle to obtain the θ angle in the latest state.

[0047] In this embodiment, another method for calibrating the angle θ without using other calibration equipment in the installation workshop is provided. It can be completed in the field. The model above has analyzed how to convert the measurement data in the equipment measurement coordinate system to the final measurement data in the site horizontal coordinate system. Therefore, the angle θ in the formula can be resolved by measuring the target multiple times.

[0048] Step 1: Level the device and guide the point target to the center of the device's field of view. At this time, record the encoder's degrees A1 and E1. At the same time, the real-time data processing end records the output angle of the orthogonal horizontal sensor in the leveling state for sensor level zeroing.

[0049] Step 2: Tilt the base of the theodolite by adjusting the leveling legs. You will find that the target gradually deviates from the center of the field of view. When the deviation between the target and the center of the field of view is 1 / 4 of the field of view, you can stop the leveling legs.

[0050] Step 3: Adjust the target to the center of the field of view again, and record the encoder output angles A2 and E2, as well as the angles α and β output by the two orthogonal sensors after zeroing and correction. B 、E B , A1, E1 as A N 、E N , and bring α and β into formulas 1, 2, and 3, and the real angle θ can be finally approached through iterative cycles.

[0051] Step 4: After iterating the angle θ through step 3, you need to verify the correctness of the value. Adjust the leveling legs of the theodolite base again so that the base tilt angle is larger than that in step 2, adjust the target to the center of the field of view again, and record the encoder readings A3 and E3 at this time. B 、E B , bring the real-time α and β into formulas 1, 2, and 3, and compare the output A N 、E N The difference between A1 and E1 is within the required measurement accuracy range, and the final θ angle is determined.

[0052] 5. Correction of the center's guidance data;

[0053] During the mission, the center will send the measurement data of other equipment to the photoelectric theodolite in real time to assist the photoelectric theodolite in capturing the target. When the base of the equipment is tilted, there is a deviation between the guidance data sent by the center and the angle of the equipment field of view. In order to better utilize the guidance data sent by the center, the guidance data sent by the center is corrected, that is, the guidance data in the horizontal coordinate system of the site is converted into the guidance data in the equipment measurement coordinate system. This process is the reverse process of the correction data above. Finally, the center guidance data A Guide 、E Guide The guidance data A′ transferred to the device measurement coordinate system Guide , E′ Guide The formula is as follows:

[0054]

[0055]

[0056]

[0057] In this embodiment, an orthogonal level sensor is used. The sensor has a simple structure, low cost, and is easy to use over a large area. At the same time, the requirements for installing the sensor are low. It only needs to be rigidly installed on the base of the photoelectric theodolite, and there are no special requirements for the installation process. The real-time data processing end can calibrate the angles of the two sensors to zero to obtain the actual inclination of the equipment base. At the same time, when determining the angle between the orthogonal sensor and the true north, that is, the initial angle θ, it can also be solved through subsequent data iterations, eliminating the tedious steps of calibration in the installation workshop. This method can directly upgrade and transform field equipment. The installation position is as follows: Figure 1 shown.

[0058] In this implementation, when performing coordinate rotation, the solution of β' is the key, because α and β are used to determine the inclination of the device base in two orthogonal coordinates. However, when rotating the coordinates, the second rotation is based on the new coordinates formed after the first rotation. At this time, β can no longer represent the coordinate angle that needs to be rotated for the second time. This value should be β', which is related to α. After the above derivation, The derivation of the β′ angle is an easily forgotten link. If it is not compensated, it is not easy to be detected at a small tilt angle, but the final measurement data correction will contain model errors.

Claims

1. A method for correcting theodolite measurement data without touching the ground based on an orthogonal level sensor, characterized by: The method is implemented by the following steps: Step 1: During the first calibration, when the theodolite is leveled, clear the angle output by the orthogonal level sensor; Step 2: Use the coordinate rotation method to correct the measured data, calculate the second coordinate rotation angle correction β′, and then determine the initial angle θ by iteration; the initial angle θ is the angle of rotation around the Y axis when the X axis of the sensor coordinate system points to the geodetic north; Step 3: Complete the correction of the equipment measurement data; that is, convert the measurement angle under the equipment measurement coordinate system into the measurement data under the site horizontal coordinate system as the final measurement result; In step 2, the measurement data is corrected by using the rotation coordinate method; that is, the device measurement coordinate system (X B ,Y B ,Z B ) to the site horizontal coordinate system (X N ,Y N ,Z N ) under the measurement data; the process from the station site horizontal coordinate system to the equipment measurement coordinate system, and the process from the equipment measurement coordinate system to the station site horizontal coordinate system is the inverse process, which only requires the inverse operation of the matrix: Step 21: Introduce the sensor coordinate system (X S ,Y S ,Z S ) as the intermediate coordinate system, determine the initial angle θ, and rotate the station horizontal coordinate system around Y N The axis rotates θ, and the horizontal coordinate system of the station is converted to the sensor coordinate system. In the sensor coordinate system, the orthogonal horizontal sensor measures the angular deviations α and β between the two axes of the theodolite and the horizontal plane. α is the X S The angle of axis tilt, β is Z S The angle of axis inclination; Step 22: Wrap around Z S The axis rotates α, and then the X B′ After the axis is rotated by β′, the plane X B′ -OZ B′ is the plane where the theodolite base is located, and the angle of the second rotation is corrected. The correction formula is: Finally around Y B′ Rotate -θ to obtain the device measurement coordinate system (X B ,Y B ,Z B ); Step 23: Set the target azimuth A in the station horizontal coordinate system N , pitch angle E N Converted to the target azimuth A in the device measurement coordinate system B , pitch angle E B ; The coordinate rotation in step 22 and step 23 is finally derived as the conversion formula from the equipment measurement coordinate system to the site horizontal coordinate system:

2. The method for correcting theodolite measurement data without touching the ground based on an orthogonal level sensor according to claim 1, characterized in that: In step 1, two level sensors are orthogonally mounted on the theodolite base; After the vehicle is leveled, leveling is achieved using an electronic level and three leveling legs provided on each theodolite base; After the theodolite base is leveled, the output angles of the two horizontal sensors are recorded using real-time data processing software, and the angles are set as the zero value of each sensor; When the theodolite base is tilted, the angles resolved into the two sensor axes are the changes relative to their respective zero position values; The zero position value is a fixed value and only needs to be calibrated once when first installed, without the need to re-measure each time the site is changed.

3. The method for correcting theodolite measurement data without touching the ground based on an orthogonal level sensor according to claim 1 or 2, characterized in that: The initial angle θ is determined by collecting measurement data in two sets of equipment measurement coordinate systems and corresponding measurement results in the site horizontal coordinate system, and by iteratively converting the model; The specific process is: Step A: Level the theodolite base, guide the point target to the center of the field of view of the device, record the angles A1 and E1 of the encoder, and at the same time, the real-time data processing end records the output angle of the orthogonal horizontal sensor in the leveling state for sensor level zeroing; Step B: By adjusting the leveling legs of the theodolite base, the base of the device is tilted, and the target is found to gradually deviate from the center of the field of view. When the deviation between the target and the center of the field of view is 1 / 4 of the field of view, the operation of the leveling legs is completed; Step C: Adjust the target to the center of the field of view again, record the encoder output angles A2 and E2 and the angles α and β of the two orthogonal sensors after zeroing and correction; use A2 and E2 as A B 、E B , A1, E1 as A N 、E N , coordinate α and β to bring the target azimuth A into the device measurement coordinate system B , pitch angle E B Converted to the target azimuth A in the station horizontal coordinate system N , pitch angle E N In formulas (1), (2), and (3), the true angle θ is finally approached through a loop iteration.

4. The method for correcting theodolite measurement data without touching the ground based on an orthogonal level sensor according to claim 3, characterized in that: Also includes step D: After iterating the angle θ through step C, verify the correctness of the value; Adjust the leveling legs of the theodolite base again to make the base tilt angle different from the tilt angle in step B, adjust the target to the center of the field of view again, and record the encoder readings A3 and E3 at this time; use A3 and E3 as A B 、E B , coordinate the real-time α and β to bring the target azimuth A in the device measurement coordinate system B , pitch angle E B Converted to the target azimuth A in the station horizontal coordinate system N , pitch angle E N In formulas (1), (2), and (3), the comparison output A N 、E N The difference between A1 and E1 is within the required measurement accuracy range, and the final θ angle is determined.

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