A GNSS-RTK device with rotating laser and its calibration and implementation method

Abstract

The present invention relates to the field of automatic control technology, and in particular to a GNSS-RTK device with a rotating laser and a calibration and implementation method, comprising establishing a rotatable laser coordinate system; calibrating a rotating laser in the rotatable laser coordinate system based on the GNSS-RTK device with a rotating laser to obtain real-time coordinates of a rotating point of a laser rangefinder module; calibrating a rotating axis of an absolute encoder motor of the GNSS-RTK device with a rotating laser and a laser rangefinder module based on the real-time coordinates; measuring the coordinates of the GNSS-RTK device with a rotating laser in real time, and obtaining a coordinate calculation result of a point to be measured through corresponding calculation. The above method enables a user to ensure that the antenna is tilted within a small angle range in conventional measurement to meet different usage scenarios, thereby improving work efficiency and measurement accuracy, and facilitating the use of points to be measured at different heights.

Description

Technical Field

[0001] The present invention relates to the field of automatic control technology, and in particular to a GNSS-RTK device with a rotating laser and a calibration and implementation method. Background Art

[0002] In modern surveying, GNSS-RTK technology plays a vital role and is widely used in land surveying, construction, topographic surveying and other fields. Traditional GNSS-RTK measurement is affected by many environmental factors, such as the inability to locate and measure where the satellite signal is blocked, the inaccessible locations, and the measurement in dangerous areas. These factors will have a lot of impact on the measurement, reduce the measurement accuracy and limit the scope of use of the instrument.

[0003] In order to overcome the limitations of traditional GNSS-RTK measurement methods, GNSS-RTK using lasers has gradually emerged in recent years. Laser GNSS-RTK can effectively make up for the shortcomings of the above-mentioned conventional RTK in use, thereby significantly improving the accuracy, reliability and application scenarios of measurement. It has shown unique advantages.

[0004] However, the laser RTK currently on the market is fixedly installed, mostly in a single horizontal direction or roughly vertical to the ground. As a result, when users use lasers to aim at positions at different heights for tilt measurement, the antenna attitude will inevitably tilt. Since the size of the multipath delay is related to the tilt direction and angle of the antenna, the multipath delay of satellite signals at different azimuths and altitudes has different change patterns, which significantly increases the impact of the multipath effect and reduces the number of valid observations. Therefore, as the antenna tilt angle increases, the GNSS positioning error increases, resulting in a significant increase in the coordinate error of the laser measurement. Summary of the invention

[0005] The purpose of the present invention is to provide a GNSS-RTK device with rotating laser and a calibration and implementation method, aiming to solve the problem that when the antenna attitude is tilted, the number of effective observation values ​​is reduced and the positioning accuracy is deteriorated.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a calibration and implementation method of a rotating laser GNSS-RTK device, comprising the following steps:

[0007] Establish a rotatable laser coordinate system;

[0008] According to the GNSS-RTK device with rotating laser, the rotating laser is calibrated in the rotatable laser coordinate system to obtain the real-time coordinates of the rotating point of the laser rangefinder module;

[0009] Calibrate the rotation axis of the absolute encoder motor with the rotating laser GNSS-RTK device and the laser rangefinder module based on the real-time coordinates;

[0010] The GNSS-RTK device with rotating laser is used to perform real-time coordinate measurement and calculation to obtain the coordinate calculation results of the points to be measured.

[0011] Wherein, the step of establishing a rotatable laser coordinate system comprises:

[0012] Taking the center O of the bottom of the GNSS-RTK device as the coordinate origin, and XY together with the left-handed rectangular coordinate system O-XYZ on the geodetic plane, a rotatable laser coordinate system is obtained.

[0013] Wherein, the GNSS-RTK device with rotating laser is used, and the rotating laser is calibrated in the rotatable laser coordinate system to obtain the real-time coordinates of the rotating point of the laser rangefinder module;

[0014] At the preset laser ranging module position, the GNSS-RTK device obtains a fixed solution, and after initial alignment, obtains the three-dimensional coordinates of the phase center and the attitude roll angle, pitch angle and heading angle of the IMU;

[0015] Calculate the coordinates of point O based on the three-dimensional coordinates of the phase center and the attitude roll angle, pitch angle and heading angle of the IMU;

[0016] The real-time coordinates of the rotation point of the laser rangefinder module are calculated based on the coordinates of the point O.

[0017] The step of calibrating the rotation axis of the absolute encoder motor with the rotating laser GNSS-RTK device and the laser beam direction of the laser rangefinder module based on the real-time coordinates includes:

[0018] Control the rotation axis of the absolute encoder motor to rotate, aim the laser beam of the laser rangefinder module at two known coordinate points in sequence, and calculate the distance from the real-time coordinate to the two known coordinate points;

[0019] A plane normal vector formed by two known coordinate points and the real-time coordinates;

[0020] Obtaining two observed angle values ​​of the absolute encoder motor;

[0021] Calculate the standard vector of the laser direction based on two known coordinate points, the angle values ​​of two observations and the distance between the two known coordinate points;

[0022] The rotation axis of the absolute encoder motor is calibrated based on the plane normal vector, and the laser beam direction of the laser rangefinder module is calibrated based on the standard vector.

[0023] In a second aspect, the present invention provides a GNSS-RTK device with a rotating laser, including a GNSS-RTK antenna, a main control board, an absolute encoding motor, a laser rangefinder module and a power supply, etc. The GNSS-RTK antenna, the absolute encoding motor, the laser rangefinder module and the power supply are all connected to the main control board, and the laser rangefinder module is fixedly connected to the absolute encoding motor.

[0024] The present invention discloses a calibration and implementation method for a GNSS-RTK device with a rotating laser. The method comprises the following steps: establishing a rotatable laser coordinate system; installing a GNSS-RTK device, and calibrating the rotating laser in the rotatable laser coordinate system to obtain the real-time coordinates of the rotating point of a laser rangefinder module; calibrating the rotating axis of an absolute encoder motor of the GNSS-RTK device with a rotating laser and the laser of the laser rangefinder module based on the real-time coordinates; and performing real-time coordinate measurement and calculation on the GNSS-RTK device with a rotating laser to obtain the coordinate calculation result of the point to be measured. The laser rangefinder module is installed on the rotatable internal absolute encoder motor in the above manner, so that when a user uses the laser GNSS-RTK, the antenna can be ensured to be tilted within a small angle range in conventional measurement to meet different usage scenarios, thereby improving work efficiency and measurement accuracy and being easy to use. The method solves the problem that the number of effective observation values ​​is reduced and the positioning accuracy is deteriorated when the antenna attitude is tilted, thereby expanding the usage scenarios and usage scope of the RTK. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the implementation examples or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 It is a schematic diagram of the relationship structure of various units of a calibration and implementation method of a rotating laser GNSS-RTK device provided by the present invention.

[0027] Figure 2 It is a schematic diagram of laser rotation angle of a calibration and implementation method of a rotating laser GNSS-RTK device provided by the present invention.

[0028] Figure 3 It is a diagram showing the position relationship with the point to be measured during the measurement alignment process.

[0029] Figure 4 This is a GNSS-RTK device that can measure rotational lasers and includes a schematic diagram of the device.

[0030] Figure 5 The figure is a top view of the structure of a GNSS-RTK device with a rotating laser provided by the present invention.

[0031] Figure 6 It is a structural front view of a GNSS-RTK device with a rotating laser provided by the present invention.

[0032] Figure 7 It is a flow chart of a calibration and implementation method of a rotating laser GNSS-RTK device provided by the present invention.

[0033] 1-GNSS-RTK antenna, 2-main control board, 3-absolute encoder motor, 4-laser rangefinder module, 5-power supply. DETAILED DESCRIPTION

[0034] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0035] See also Figures 1 to 7 The present invention provides a calibration and implementation method of a rotating laser GNSS-RTK device, comprising the following steps:

[0036] S1 establishes a rotatable laser coordinate system;

[0037] Specifically, the center O at the bottom of the GNSS-RTK device is taken as the coordinate origin, and XY forms a rectangular left-handed coordinate system O-XYZ on the geodetic plane to obtain a rotatable laser coordinate system.

[0038] like Figure 1 As shown, the center O at the bottom of the instrument (GNSS-RTK equipment) is taken as the coordinate origin, and it forms the geodetic plane rectangular coordinate system O-XYZ with XY. A is the phase center of the GNSS-RTK antenna 1, and both point A and point O are located on the rotation axis at the center of the instrument. In particular, when the instrument is plumb, the OA direction coincides with the Z axis. The inertial navigation is integrated with the main control board 2, the GPS main board, etc., and can obtain information such as the instrument phase center coordinates, attitude and heading angle (and convert it into the required azimuth angle). The rotation axis of the absolute encoder motor 3 is VV′, and the rotation angle of the absolute encoder motor 3 is set in the clockwise direction, with an angle range of 0 to 360°, as shown in FIG. Figure 2As shown, when the laser rangefinder module 4 is roughly horizontal, the angle of the absolute encoder motor 3 is set to 90 degrees, increasing in the clockwise direction. The absolute encoder motor 3 is fixedly installed together with the machine housing, the main control board 2, the GNSS-RTK antenna 1 and other equipment. The laser rangefinder module 4 is fixed together with the absolute encoder motor 3 and can rotate. The laser direction UU' is perpendicular to VV' and intersects at point J. Point J is projected on the plane as point M. In the O-XYZ coordinate system, the design coordinates of point J are (x J ,y J ,z J ), the design value of the distance from phase center A to O is V.

[0039] S2 is based on a GNSS-RTK device with a rotating laser, and calibrates the rotating laser in the rotatable laser coordinate system to obtain the real-time coordinates of the rotating point of the laser rangefinder module;

[0040] Specifically, at the preset laser ranging module position, the GNSS-RTK device obtains a fixed solution, and after initial alignment, obtains the three-dimensional coordinates of the phase center and the attitude roll angle, pitch angle and heading angle of the IMU; the coordinates of point O are calculated based on the three-dimensional coordinates of the phase center and the attitude roll angle, pitch angle and heading angle of the IMU; the real-time coordinates of the rotation point of the laser rangefinder module 4 are calculated based on the coordinates of point O.

[0041] Since the laser rangefinder module 4 itself is affected by the uncertainty of the laser pointing direction and the equipment installation error during the manufacturing process, it must be calibrated before use.

[0042] like Figure 2 As shown, the instrument is placed at a certain location. After the initial alignment by GNSS and inertial navigation fusion, the three-dimensional coordinates of the phase center A are obtained as (X A ,Y A ,Z A ), the attitude of IMU (roll angle, pitch angle, and heading angle are γ, θ, ψ respectively).

[0043] 1. Calculation of the coordinates of point O:

[0044] The rotation matrices of γ, θ, and ψ are as follows:

[0045] Rotate γ angle around the X axis (roll angle)

[0046]

[0047] Rotate the Y axis by an angle of θ (pitch angle)

[0048]

[0049] Rotate ψ angle around Z axis (heading angle)

[0050]

[0051] The rotation matrix is:

[0052]

[0053] In any posture, the phase center coordinates can be converted to three-dimensional coordinates at any position along the instrument's rotation axis according to different lengths. Assume that the normal vector of the horizontal plane where point O is located is n = (0,0,1). Relative to the phase center, the coordinate correction per unit length along the instrument's rotation axis is:

[0054]

[0055] For the convenience of discussion, it is made consistent with the measurement coordinate system. x is the north direction; δP y is the east direction, δP z With δP x ,δP y Vertically, forming the northeast right-hand coordinate system, the distance from point O to the phase center is V, then the coordinate increment of point O relative to the phase center A can be obtained as:

[0056]

[0057] Therefore, the three-dimensional coordinates of point O can be obtained in real time:

[0058]

[0059] 2. Real-time coordinate calculation of rotation point J of laser rangefinder module 4

[0060] The design coordinates of point J relative to point O are (x J ,y J ,z J ), then in any state, the real-time coordinates of point J for:

[0061]

[0062] S3 calibrates the rotation axis of the absolute encoder motor with the rotating laser GNSS-RTK device and the laser beam direction of the laser rangefinder module 4 based on the real-time coordinates;

[0063] Specifically, the rotation axis of the absolute encoding motor 3 is controlled to rotate, the laser of the laser rangefinder module 4 is aimed at two known coordinate points in sequence, and the distance from the real-time coordinate to the two known coordinate points is calculated; a plane normal vector is formed by the two known coordinate points and the real-time coordinates; the angle value of the two observations of the absolute encoding motor 3 is obtained; based on the two known coordinate points, the angle degrees of the two observations and the distance between the two known coordinate points, the standard vector of the laser direction is calculated; the rotation axis of the absolute encoding motor 3 is calibrated based on the plane normal vector, and the laser beam direction of the laser rangefinder module 4 is calibrated based on the standard vector.

[0064] Due to the influence of manufacturing and installation errors, the rotation axis and laser direction of the absolute encoder motor 3 often do not coincide with the ideal design position. Therefore, calibration is required before use.

[0065] like Figure 3 As shown, after the instrument is placed, it remains stationary, and then the absolute encoder motor 3 is controlled to rotate, and the laser is sequentially aimed at two known coordinate points P1 and P2, whose coordinates are The distances from the rotation center J of the laser rangefinder module 4 to the points P1 and P2 are L1 and L2 respectively, and the corresponding angle readings of the absolute encoder motor 3 are τ1 and τ2 respectively.

[0066] 1. The normal vector of the plane formed by the three points P1, P2, and J is the rotation axis vector of the absolute encoder motor 3 in this state.

[0067]

[0068]

[0069]

[0070] in

[0071]

[0072] 2. Find the standard vector of the laser direction

[0073]

[0074]

[0075] After standardization:

[0076]

[0077]

[0078] During the two observations, the reading values ​​of the second observation of the absolute encoder motor 3 are uniformly calculated to the position where the angle of the absolute encoder motor 3 is zero. According to the Rodrigues formula:

[0079] N1 0 =N1 cosβ1+(N VV′ ×N1)sinβ1+(N VV′ ·N1)N VV′ (1-cosβ1)

[0080]

[0081] Calculate the weighted average value based on the length of distance L1 and L2

[0082]

[0083]

[0084] S4 performs real-time coordinate measurement and calculation on the GNSS-RTK device to obtain coordinate calculation results of the points to be measured.

[0085] Specifically, Figure 3 As shown, suppose the instrument is placed at a certain position. After initial alignment, the three-dimensional coordinates of the phase center A are obtained as (X A ,Y A ,Z A ), the roll angle, pitch angle, and heading angle of the IMU are γ, θ, and ψ respectively. When aiming at any point P to be measured, the angle reading of the absolute encoder motor 3 is β, and the distance is L, then:

[0086]

[0087]

[0088]

[0089]

[0090]

[0091]

[0092]

[0093]

[0094]

[0095]

[0096] The coordinates of point P are

[0097]

[0098] In the second aspect, the present invention provides a GNSS-RTK device with a rotating laser, including a GNSS-RTK antenna 1, a main control board 2, an absolute encoding motor 3, a laser rangefinder module 4 and a power supply 5, wherein the GNSS-RTK antenna 1, the absolute encoding motor 3, the laser rangefinder module 4 and the power supply 5 are all connected to the main control board 2, and the laser rangefinder module 4 is fixedly connected to the absolute encoding motor 3.

[0099] Specifically, it also includes a centering rod, wherein the laser rangefinder module 4 is integrated into the GNSS-RTK antenna 1, and the line connecting the antenna phase center of the GNSS-RTK antenna 1 is consistent with the centering rod. The present invention adopts a rotatable laser method to install the laser rangefinder module 4 on a rotatable internal absolute encoder motor 3, so that when the user uses the laser GNSS-RTK, in conventional measurements, the antenna can be ensured to be tilted within a small angle range to meet different usage scenarios, thereby significantly improving the positioning accuracy of the laser GNSS-RTK measurement.

[0100] The above disclosure is only a preferred embodiment of a GNSS-RTK device and calibration and implementation method of the present invention. Of course, this cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of implementing the above embodiments and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A calibration and implementation method for a rotating laser GNSS-RTK device, characterized in that: The following steps are involved: Establish a rotatable laser coordinate system; According to the GNSS-RTK device with rotating laser, the rotating laser is calibrated in the rotatable laser coordinate system to obtain the real-time coordinates of the rotation point of the laser rangefinder module, wherein the rotation point refers to the intersection of the rotation axis of the absolute encoder motor and the laser direction; Calibrate the rotation axis of the absolute encoder motor with the rotating laser GNSS-RTK device and the laser beam direction of the laser rangefinder module based on the real-time coordinates; The GNSS-RTK device with rotating laser is used to perform real-time coordinate measurement and calculation to obtain the coordinate calculation results of the points to be measured.

2. The calibration and implementation method of the GNSS-RTK device according to claim 1, characterized in that: The step of establishing a rotatable laser coordinate system comprises: Taking the center O of the bottom of the GNSS-RTK device as the coordinate origin, and XY together with the left-handed rectangular coordinate system O-XYZ on the geodetic plane, a rotatable laser coordinate system is obtained.

3. The calibration and implementation method of the GNSS-RTK device according to claim 2, characterized in that: The method is based on a rotating laser GNSS-RTK device and calibrates the rotating laser in the rotatable laser coordinate system to obtain the real-time coordinates of the rotating point of the laser rangefinder module, including: At the preset laser ranging module position, the GNSS-RTK device obtains a fixed solution, and after initial alignment, obtains the three-dimensional coordinates of the phase center and the attitude roll angle, pitch angle and heading angle of the IMU; Calculate the coordinates of point O based on the three-dimensional coordinates of the phase center and the attitude roll angle, pitch angle and heading angle of the IMU; The real-time coordinates of the rotation point of the laser rangefinder module are calculated based on the coordinates of the point O.

4. The calibration and implementation method of the GNSS-RTK device according to claim 3, characterized in that: The method of calibrating the rotation axis of the absolute encoder motor with the rotating laser GNSS-RTK device and the laser beam direction of the laser rangefinder module based on the real-time coordinates includes: Control the rotation axis of the absolute encoder motor to rotate, aim the laser beam of the laser rangefinder module at two known coordinate points in sequence, and calculate the distance from the real-time coordinate to the two known coordinate points; Calculate the plane normal vector of the plane formed by the two known coordinate points and the real-time coordinates; Obtaining two observed angle values ​​of the absolute encoder motor; Calculate the standard vector of the laser direction based on two known coordinate points, the angle values ​​of the two observations and the distance from the real-time coordinate to the two known coordinate points; The rotation axis of the absolute encoder motor is calibrated based on the plane normal vector, and the laser beam direction of the laser rangefinder module is calibrated based on the standard vector.

5. A GNSS-RTK device with a rotating laser, applied to the calibration and implementation method of the GNSS-RTK device according to claim 4, characterized in that: It includes a GNSS-RTK antenna, a main control board, an absolute encoding motor, a laser rangefinder module and a power supply, etc. The GNSS-RTK antenna, the absolute encoding motor, the laser rangefinder module and the power supply are all connected to the main control board, and the laser rangefinder module is fixedly connected to the absolute encoding motor.

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