Method and system for automatically compensating dynamic displacement of RTK base station

Abstract

The present invention discloses a method and system for automatically compensating for the dynamic displacement of an RTK base station. By adopting a high-precision displacement sensor, the displacement can be detected more accurately to achieve displacement compensation. The RTK base station system has the advantage of being able to provide accurate RTK base station coordinate data even when it moves. By adopting a displacement compensation technology, the method has the advantage of not only being able to detect the movement, but also ensuring compensation after the movement, thereby achieving the advantage of still being usable after the movement.

Description

Technical Field

[0001] The present invention relates to the field of RTK positioning of unmanned aerial vehicles, and in particular to a method and system for automatically compensating for dynamic displacement of an RTK reference station. Background Art

[0002] RTK positioning technology: Real-time kinematic (RTK) positioning technology is a high-precision positioning method based on the Global Navigation Satellite System (GNSS). The base station compares the satellite's position data with its own precise known position, including the RTK base station and the mobile station: both stations are equipped with satellite receivers that can observe and receive satellite data. The base station is a base station that provides a reference benchmark and is generally not movable, otherwise the benchmark data sent will be wrong, while the mobile station is a station that can move continuously. The mobile station is actually the object target that measures its own three-dimensional coordinates, that is, the user terminal.

[0003] The patent "CN107991694A A RTK base station attitude monitoring system and monitoring method thereof" has a design point that an electronic bubble module is provided to detect whether the RTK module has moved, but the amount of movement cannot be measured or compensated. The electronic bubble can only be used to determine whether the base station has been moved, and cannot accurately measure the displacement of the movement, nor can it solve the problem of large positioning deviation of the mobile station caused by the base station data offset after the movement.

[0004] The patent "CN116719067A Base station position change detection method, device and readable storage medium" has a design point that the self-moving device determines whether the base station has not been moved by combining visual images and the movement characteristics of the self-moving device. It cannot solve the problem that the mobile station cannot be accurately positioned after the base station is moved.

[0005] The patent "CN117270003A RTK positioning method, mobile device, base station and storage medium" has the following design points: receiving differential corrections and ID identifiers sent by at least two base stations; performing RTK solution based on its own observations, the differential corrections and ID identifiers of each base station at the same time; and positioning based on two sets of RTK solution results. The mobile station needs to solve the data of the two base stations based on its own calculations, and use the differential corrections and ID factors to judge the reliability of the base station data. The main disadvantage of its design is that it cannot solve the situation where both base stations move, resulting in the data of both base stations being unavailable. Moreover, it uses the mobile station as a judgment and solution to the problem caused by the movement of one of the two base stations, and the system is too complex and highly coupled.

[0006] In summary, a method and system for automatically compensating for the dynamic displacement of an RTK reference station is needed to address the deficiencies in the prior art. Summary of the invention

[0007] In view of the problem in the prior art that the movement of the base station will cause the RTK differential correction data output by the base station to change, thereby rendering the RTK differential correction data received by the mobile station unusable, the present invention provides a method and system for automatically compensating for the dynamic displacement of the RTK base station, aiming to solve the above problem.

[0008] To achieve the above object, the present invention provides the following technical solution: a method and system for automatically compensating for the dynamic displacement of an RTK reference station, comprising the following steps:

[0009] Step S1: The RTK receiver of the base station receives pseudo-range observations ρi from more than three satellite data and calculates the real-time position coordinates Si and position correction numbers Li;

[0010] Step S2: The displacement sensor of the base station integrates the acceleration data detected by the inertial measurement sensor of the IMU to obtain the displacement △;

[0011] Step S3: The real-time processor fuses the fixed coordinates of the base station and the relative displacement △ calculated by the RTK module to obtain a real-time correction number;

[0012] Step S4: The base station sends the real-time position coordinates and real-time correction numbers to the mobile station;

[0013] Step S5: The mobile station performs real-time dynamic differential positioning according to the received data;

[0014] Step S6: The base station processor records and stores the displacement, and guides the training RTK base station positioning module to reposition.

[0015] Optionally, the real-time position coordinates in step S1 are calculated in the following manner:

[0016] Set the base station location coordinates to , calculated based on pseudo-range observations from satellite data:

[0017] ,

[0018] ,

[0019] ,

[0020] in, , , is the pseudo-range observation from the satellite to the receiver at a certain moment, are the coordinates of three satellites at the same time, where n=1,2,3,

[0021] The base station location coordinates are calculated from this ,

[0022] Then, according to the base station location coordinates, the real-time location coordinates Si of the reference station at the current moment are obtained. .

[0023] Optionally, the position correction number Li in step S1 is calculated by:

[0024] , , ,

[0025] In the formula, The base station has fixed coordinates. is the real-time position coordinate of the base station.

[0026] Optionally, the relative displacement Δ in step S2 is calculated by:

[0027] ,

[0028] ,

[0029] ,

[0030] In the formula, , , is the displacement of the three axes at time t, , , is the position of the three axes at the initial moment, , , is the speed of the three axes at time t.

[0031] Optionally, the speeds of the three axes at time t are calculated in the following manner:

[0032] ,

[0033] ,

[0034] ,

[0035] In the formula, , , is the three-axis speed at the initial moment, , , is the acceleration of the three axes.

[0036] Optionally, the acceleration of the three axes is calculated in the following manner:

[0037] ,

[0038] ,

[0039] ,

[0040] In the formula, , , is the current estimate of acceleration, , , is the estimated value of acceleration at the previous moment, , , is the current and speedometer measurement value, is the Kalman gain,

[0041] The filtered acceleration data is continuously updated according to the deviation.

[0042] Optionally, the real-time correction number in step S3 is calculated in the following manner:

[0043] ,

[0044] ,

[0045] ,

[0046] In the formula, The base station has fixed coordinates. is the real-time position coordinate of the base station, , , is the displacement of the three axes.

[0047] Optionally, the positioning coordinates of the real-time dynamic differential positioning in step S5 are Calculated by:

[0048] , , ,

[0049] In the formula, is the real-time satellite position coordinates, It is the real-time correction number.

[0050] A dynamic displacement system for automatically compensating an RTK base station includes a displacement sensor, a real-time processor, a storage device, an RTK base station and an RTX mobile station.

[0051] Displacement sensor, which monitors the displacement of the base station and is used to adjust and correct RTK data in a timely manner;

[0052] A real-time processor is suitable for processing the data received from the satellite, the displacement information provided by the displacement sensor and the positioning information of the base station;

[0053] Storage device, used to save the static information of the base station, historical displacement data, intermediate and result information during the calculation process;

[0054] The RTK base station, as a fixed reference point, is used to receive satellite signals and generate position corrections through calculations. The position corrections are used to improve the positioning accuracy of the mobile station.

[0055] The RTX mobile station, as a moving reference point, receives corrections from the RTK base station and uses the corrections combined with the satellite signals it receives to improve positioning accuracy.

[0056] Beneficial effects of the present invention:

[0057] 1. In the present invention, by using a high-precision displacement sensor, the displacement can be detected more accurately and displacement compensation can be achieved. The RTK base station system has the advantage of providing accurate RTK base station coordinate data even when it moves. The displacement compensation technology is adopted. The method has the advantage of not only being able to detect the movement, but also ensuring compensation after the movement, thereby achieving the advantage of still being usable after the movement;

[0058] 2. In the present invention, a real-time processor is used to fuse the positioning data and the displacement for a second time and then send it out. The mobile station receives the optimal positioning reference data, which has the advantage that the RTK reference station system does not rely on external mobile stations when compensating for its own movement.

[0059] 3. In the present invention, a real-time detection system for communication between a processor and a storage device is adopted, which has the advantage of judging the credibility of data from the size of the displacement, and adopts a dynamic displacement compensation algorithm, which has the advantage of not interrupting the transmission of RTCM dynamic differential positioning data during the movement of the base station. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 The present invention is a flow chart of a method.

[0061] Figure 2 A system structure diagram of the present invention. DETAILED DESCRIPTION

[0062] In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0063] like Figure 1 As shown, a method for automatically compensating for the dynamic displacement of an RTK base station is provided. The RTK receiver of the base station receives pseudo-range observations ρi from more than three satellite data and calculates the real-time position coordinates Si and the position correction number Li.

[0064] The calculation process is as follows, setting the base station location coordinates to , calculated based on pseudo-range observations from satellite data:

[0065] ,

[0066] ,

[0067] ,

[0068] in, , , is the pseudo-range observation from the satellite to the receiver at a certain moment, are the coordinates of three satellites at the same time, where n=1,2,3,

[0069] The above equation can be used to calculate the base station location coordinates ,

[0070] Then, according to the base station location coordinates, the real-time location coordinates Si of the reference station at the current moment are obtained. .

[0071] Secondly, the coordinates actually calculated this time are subtracted from the absolute position coordinates of the base station to obtain the position correction number Li at that moment.

[0072] , , ,

[0073] In the formula, The base station has fixed coordinates. is the real-time position coordinate of the base station.

[0074] Base station fixed coordinates , which can be the coordinates obtained by high-precision surveying known before the base station is set up, or the m real-time position coordinates obtained by the base station within a period of time can be calculated according to the following formula Calculate the mean and get:

[0075] ,

[0076] ,

[0077] ,

[0078] In the formula, is the real-time position coordinate of the base station calculated at time i, where i=1,2,3…m, and m is the number of times the real-time position coordinate of the base station is calculated within a period of time.

[0079] In the above steps, the final correction number is the real-time position coordinates at time i minus the fixed coordinates of the base station. This is based on the assumption that the base station has not been moved from time i-1 to time i, which will not affect the result of the correction number. However, if the base station has been moved from time i-1 to time i, the above correction number calculation will be the real-time coordinate position at time i minus the fixed position of the base station at time i, and the data will not be real-time. Therefore, the displacement between time i-1 and time i needs to be estimated to recalculate the correction number.

[0080] The high-precision displacement sensor of the base station is used to detect the relative displacement of the base station. Specifically, the acceleration data detected by the IMU inertial measurement sensor is integrated twice to solve the displacement. However, there is an error accumulation problem in the integral calculation, so the data needs to be filtered and calibrated. We sample the principle of the Kalman filter algorithm and estimate the accelerometer data volume through a linear equation. The linear state equation is as follows:

[0081] ,

[0082] ,

[0083] ,

[0084] In the formula, , , is the current estimate of acceleration, , , is the estimated value of acceleration at the previous moment, , , is the current and speedometer measurement value, is the Kalman gain.

[0085] The Kalman gain is continuously updated based on the deviation between the last measured value and the estimated value. According to the above calculation process, the filtered acceleration data can be obtained, and then the acceleration data can be integrated once to obtain the speed, and the double integration can obtain the position. The calculation formula and process are as follows:

[0086] ,

[0087] ,

[0088] ,

[0089] In the formula, , , is the three-axis speed at the initial moment, , , is the acceleration of the three axes

[0090] Considering that the initial velocity is 0, , so we can get

[0091] ,

[0092] ,

[0093] ,

[0094] According to the fact that the integral of velocity is equal to displacement, we can get the following formula:

[0095] ,

[0096] ,

[0097] ,

[0098] In the formula, , , is the position of the three axes at the initial moment, , , is the speed of the three axes at time t. , , As the reference point, the displacement of the coordinates relative to the reference point is:

[0099] ,

[0100] ,

[0101] ,

[0102] In the formula, , , is the displacement of the three axes at time t, , , is the position of the three axes at the initial moment, , , is the speed of the three axes at time t.

[0103] The real-time processor fuses the real-time position coordinates calculated by the RTK module and the calculated displacement data to obtain real-time correction data:

[0104] ,

[0105] ,

[0106] ,

[0107] In the formula, The base station has fixed coordinates. is the real-time position coordinate of the base station, , , is the relative displacement of the three axes, is the real-time position coordinate of the base station.

[0108] The base station sends the above real-time position coordinates and real-time corrections to the mobile station according to the standard protocol. Since the distance between the mobile station and the base station is within 20km, compared with the 20,000km distance between the station and the satellite, the satellite clock error, receiver clock error, ionosphere and atmosphere at the same time are almost the same, so the base station and the receiving station can share their corrections. The mobile station can also solve its own real-time position coordinates based on the data of the three satellites in step 1. , and then add the corrections reported by the base station According to the ideal position difference principle, the receiving station RTK differential positioning coordinates It can be calculated according to the following method:

[0109] , , ,

[0110] In the formula, is the real-time satellite position coordinates, It is the real-time correction number.

[0111] According to the above calculation process, it can be seen that after estimating the displacement of the base station, when the base station moves, the displacement will not be superimposed on the satellite correction number, thereby avoiding the phenomenon of drift affecting the receiving station.

[0112] like Figure 2 As shown, a dynamic displacement system for automatically compensating an RTK base station includes a displacement sensor, a real-time processor, a storage device, an RTK base station and an RTX mobile station.

[0113] Displacement sensor, which monitors the displacement of the base station and is used to adjust and correct RTK data in a timely manner;

[0114] A real-time processor is suitable for processing the data received from the satellite, the displacement information provided by the displacement sensor and the positioning information of the base station;

[0115] Storage device, used to save the static information of the base station, historical displacement data, intermediate and result information during the calculation process;

[0116] The RTK base station, as a fixed reference point, is used to receive satellite signals and generate position corrections through calculations. The position corrections are used to improve the positioning accuracy of the mobile station.

[0117] The RTX mobile station, as a moving reference point, receives corrections from the RTK base station and uses the corrections combined with the satellite signals it receives to improve positioning accuracy.

[0118] The working principle of the present invention is: a high-precision displacement sensor, such as an inertial measurement unit (IMU), is used to detect the displacement of the base station. This sensor can not only detect the movement of the base station, but also estimate the displacement through integral calculation, thereby realizing real-time compensation for the displacement of the base station.

[0119] Virtual coordinate update: By fusing the displacement and fixed coordinate solutions, the virtual coordinates of the base station are calculated, representing the actual position of the base station. Even if the base station moves, the accuracy of the RTK correction numbers it outputs can be maintained.

[0120] Integrate to solve displacement: Use the accelerometer data in the IMU to solve the displacement through integration. In order to reduce the accumulated error in the integration process, the Kalman filter algorithm is used to correct the data to ensure the accuracy of the displacement.

[0121] Coordinate correction and data fusion: The real-time processor of the base station fuses the displacement with the original coordinates to correct the coordinates of the base station. It can also selectively send the displacement and original coordinates to the receiving station, which performs the coordinate correction.

[0122] Continuous observation and optimization: By continuously observing and recording the displacement of the base station, the position solution of the base station can be further optimized to improve the overall performance of the system.

[0123] Wide application of the principle: The optimization principle is not only applicable to RTK positioning technology, but can also be extended to other positioning systems based on pseudorange measurement and carrier phase measurement. Whether in RTK or other differential positioning technologies, the offset of the base station correction number can be corrected by a similar method.

[0124] Application of the position difference principle: The correction method of the base station correction number is also applicable to positioning technology based on the position difference principle. Whether it is the technology of calculating the position of the receiving station based on the pseudo-range difference or the carrier phase difference principle, this method can be used as a reference for improvement.

[0125] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for automatically compensating for the dynamic displacement of an RTK reference station, characterized in that: The following steps are involved: Step S1: The RTK receiver of the base station receives pseudo-range observations ρi from more than three satellite data and calculates the real-time position coordinates Si and position correction numbers Li; The position correction Li is calculated as follows: ， ， ， In the formula, The fixed coordinates of the base station, is the real-time position coordinates of the base station; Step S2: The displacement sensor of the base station integrates the acceleration data detected by the inertial measurement sensor of the IMU to obtain the relative displacement △; Step S3: The real-time processor fuses the fixed coordinates of the base station and the relative displacement △ calculated by the RTK module to obtain a real-time correction number; Real-time corrections are calculated as follows: ， ， ， In the formula, The fixed coordinates of the base station, is the real-time position coordinate of the base station, , , is the relative displacement of the three axes; Step S4: The base station sends the real-time position coordinates and real-time correction numbers to the mobile station; Step S5: The mobile station performs real-time dynamic differential positioning according to the received data; Positioning coordinates of real-time dynamic differential positioning Calculated by: ， ， ， In the formula, is the real-time satellite position coordinates, It is the real-time correction number; Step S6: The base station processor records and stores the displacement, and guides the training RTK base station positioning module to reposition.

2. The method for automatically compensating for dynamic displacement of an RTK reference station according to claim 1, characterized in that: The real-time position coordinates in step S1 are calculated in the following manner: Set the base station location coordinates to , calculated based on pseudo-range observations from satellite data: ， ， ， In the formula, , , is the pseudo-range observation from the satellite to the receiver at a certain moment, are the coordinates of three satellites at the same time, where n=1,2,3, The base station location coordinates are calculated from this , Then, according to the base station location coordinates, the real-time location coordinates Si of the reference station at a certain moment are obtained. .

3. The method for automatically compensating for dynamic displacement of an RTK reference station according to claim 2, characterized in that: The relative displacement Δ in step S2 is calculated by the following method: ， ， ， In the formula, , , is the displacement of the three axes at time t, , , is the initial position of the three axes, , , are the speeds of the three axes at time t.

4. The method for automatically compensating for dynamic displacement of an RTK reference station according to claim 3, characterized in that: The displacement of the three axes at time t is calculated in the following way: ， ， ， In the formula, , , is the initial position of the three axes, , , are the speeds of the three axes at time t.

5. The method for automatically compensating for dynamic displacement of an RTK reference station according to claim 4, characterized in that: The speeds of the three axes at time t are calculated as follows: ， ， ， In the formula, , , is the three-axis speed at the initial moment, , , is the acceleration of the three axes.

6. The method for automatically compensating for dynamic displacement of an RTK reference station according to claim 5, characterized in that: The acceleration of the three axes is calculated as follows: ， ， ， In the formula, , , is the current estimate of acceleration, , , is the estimated value of acceleration at the previous moment, , , is the current and speedometer measurement value, is the Kalman gain, The filtered acceleration data is continuously updated according to the deviation.

7. A system for automatically compensating for the dynamic displacement of an RTK reference station, using the method for automatically compensating for the dynamic displacement of an RTK reference station as claimed in any one of claims 1 to 6, characterized in that: Including displacement sensor, real-time processor, storage device, RTK base station and RTX mobile station, Displacement sensor, which monitors the displacement of the base station and is used to adjust and correct RTK data in a timely manner; A real-time processor is suitable for processing the data received from the satellite, the displacement information provided by the displacement sensor and the positioning information of the base station; Storage device, used to save the static information of the base station, historical displacement data, intermediate and result information during the calculation process; The RTK base station, as a fixed reference point, is used to receive satellite signals and generate position corrections through calculations. The position corrections are used to improve the positioning accuracy of the mobile station. The RTX mobile station, as a moving reference point, receives corrections from the RTK base station and uses the corrections combined with the satellite signals it receives to improve positioning accuracy.

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