A method and system for positioning a shooting terminal in a strong electromagnetic environment that integrates RTK anti-interference and attitude calculation

Abstract

This invention provides a method and system for locating a camera terminal in a strong electromagnetic environment, integrating RTK anti-interference and attitude calculation, belonging to the field of RTK positioning. It solves the problem that equipment self-positioning in strong electromagnetic environments is susceptible to external electromagnetic interference. The method includes the following steps: constructing a strapdown inertial navigation system; constructing an RTK multipath cancellation-dual-difference positioning model, which integrates multipath suppression and differential positioning techniques. Direct wave cancellation technology is used to eliminate multipath interference signals with fixed delay and amplitude attenuation relationships to the direct wave signal. Simultaneously, real-time differential calculation is performed using RTK dual-difference positioning. The dual-difference positioning method, combined with a high-difference cycle slip recovery strategy, detects and corrects cycle slip deviations generated during signal propagation. Position calculation is performed using dual-difference observations. An extended Kalman filter is introduced to fuse the RTK positioning data and attitude perception data of the camera terminal to obtain the real-time position information of the camera terminal. This invention is applied to the positioning of camera terminals in substations.

Description

Technical Field

[0001] This invention provides a method and system for positioning a shooting terminal in a strong electromagnetic environment that integrates RTK anti-interference and attitude calculation, belonging to the field of RTK positioning technology. Background Technology

[0002] High-precision positioning technology is currently widely used in various industries, such as automobiles, drones, substations, etc. Commonly used positioning methods include GPS positioning, Beidou positioning, inertial navigation positioning, base station positioning, Bluetooth positioning, etc. In GPS positioning, RTK differential technology can improve positioning accuracy. However, RTK differential technology also faces various problems in practical applications due to the diversity of application environments. To address these issues, scholars have proposed different methods. For example, Chinese patent CN118294994A fully considers the deviation problems caused by environmental factors such as the atmosphere and ionosphere during satellite signal propagation and discloses an RTK inertial deep combined carrier phase tracking control method. Drawing on the concept of differential positioning, it introduces RTK differential information to eliminate errors such as ionospheric delay and tropospheric delay to reduce satellite observation errors, which can effectively alleviate integer ambiguity and cycle slip problems and improve RTK positioning accuracy. Another example is Chinese patent CN118311630A, which considers that UAV-driven loaders have high positioning accuracy requirements. However, when the UAV is turning or moving on rough roads, RTK is affected by atmospheric conditions and cannot quickly and accurately locate the vehicle's attitude and speed information, resulting in poor attitude calculation stability. It proposes a high-precision positioning method for UAV-driven loaders based on RTK and IMU. By adding the installation error angle between the IMU coordinate system and the carrier coordinate system to the state vector for filtering estimation, the positioning and attitude calculation accuracy of the integrated navigation system can be improved. Chinese patent CN118348563A addresses the multipath effect caused by signal reflection from multiple buildings on roads in real-world driving environments. It discloses a method and system for identifying RTK positioning accuracy, combining vehicle-road perception information and RTK positioning information to determine the RTK positioning accuracy. Chinese patent CN118534497A addresses the multipath effect caused by numerous obstructions in complex mountainous environments. It discloses a multi-source adaptive positioning method and system that processes GNSS data and base station data in a multi-source heterogeneous sensor fusion enhancement module using an RTK positioning algorithm to obtain more accurate differential positioning information.

[0003] However, the aforementioned patents only address the indirect interference caused by atmospheric propagation errors or multipath effects during RTK signal reception. In contrast, in strong electromagnetic environments like substations, the dense distribution of high-voltage power equipment creates significant electromagnetic interference for RTK receivers and inertial sensors. This interference not only degrades the signal quality of the RTK receiver, leading to positioning data deviations, but also significantly reduces the stability of attitude calculations. Furthermore, buildings and high-voltage power equipment, as large physical obstacles, not only directly block the straight-line propagation path of RTK signals, but also, due to their metallic material and complex structure, cause significant reflection and scattering of the signals. This results in multiple paths for the signal to reach the RTK receiver, and the superposition and interference of these signals further reduce the accuracy of RTK positioning.

[0004] Furthermore, in practice, inertial measurement units (IMUs) are a commonly used technique for measuring the spatial attitude of equipment. However, the angular velocity obtained by the gyroscope will have cumulative errors over time, and the magnetometer is easily interfered with in strong electromagnetic environments, resulting in inaccurate measurement data and poor stability of attitude calculation. Summary of the Invention

[0005] To address the issue of equipment self-positioning being susceptible to external electromagnetic interference in strong electromagnetic environments, this invention proposes a method and system for positioning a shooting terminal in strong electromagnetic environments that integrates RTK anti-interference and attitude calculation. This method can enhance the shooting terminal's ability to accurately capture position and attitude data in strong electromagnetic environments and improve the target positioning accuracy in images captured by the shooting terminal in strong electromagnetic environments.

[0006] The technical solution adopted in this invention is: a method for positioning a shooting terminal in a strong electromagnetic environment that integrates RTK anti-interference and attitude calculation, comprising the following steps:

[0007] S1: Construct a strapdown inertial navigation system and use the strapdown inertial navigation system to calculate the attitude data of the shooting terminal in a strong electromagnetic environment;

[0008] S2: Construct an RTK multipath cancellation-dual-difference positioning model. The model integrates multipath suppression and differential positioning technologies. It uses direct wave cancellation technology to eliminate multipath interference signals that have a fixed delay and amplitude attenuation relationship with the direct wave signal. At the same time, it combines RTK dual-difference positioning to perform real-time differential calculation. It uses dual-difference positioning combined with the high-difference cycle slip recovery strategy to detect and correct cycle slip deviations generated during signal propagation. It uses dual-difference observations to calculate the position and obtain the precise position information of the shooting terminal.

[0009] S3: An extended Kalman filter is introduced to fuse the RTK positioning data and attitude perception data of the shooting terminal to obtain the final real-time location information of the shooting terminal.

[0010] The strapdown inertial navigation system includes a 3-axis gyroscope, a 3-axis angular velocity meter, a 3-axis magnetometer, a barometer, and a digital motion processor, which simultaneously measures the attitude, angular velocity, geomagnetic field, and air pressure data of the shooting terminal.

[0011] The digital motion processor constructs state equations and observation equations to solve and obtain the raw data of the posture as a state variable.

[0012] The specific implementation process of eliminating multipath interference signals that have a fixed delay and amplitude attenuation relationship with the direct wave signal using direct wave cancellation technology in step S2 is as follows:

[0013] A multipath canceller is set in the reference channel, and an adaptive algorithm is used to estimate and cancel the multipath signal, thereby obtaining a purified reference direct wave signal.

[0014] Then, the reference direct wave signal obtained in the previous step is subjected to minimum mean square error (LMS) adaptive filtering in the target channel to suppress direct wave interference.

[0015] The specific implementation process of detecting and correcting cycle slip deviations generated during signal propagation using the double-difference positioning method combined with the high-difference secondary method cycle slip recovery strategy in step S2 is as follows:

[0016] First, a discontinuous epoch cycle slip detection method based on the higher order difference method is introduced to preprocess the signal after direct wave cancellation;

[0017] Then, calculate the initial coordinates of the imaging terminal relative to the satellite;

[0018] Finally, by combining observation data from multiple satellites, the current three-dimensional coordinates of the imaging terminal are solved using the weighted least squares method.

[0019] The process of preprocessing the signal after direct wave cancellation based on the high-order difference method and the discontinuous epoch cycle slip detection method is as follows:

[0020] Interruption counting is performed at the epoch of data loss, assuming the epoch is t1 and the epoch of reacquisition is t2, then the loss time is Δt = t2 - t1; the sampling interval of the high-order difference method is set to the calculated loss time Δt to ensure equal interval sampling; the signal after direct wave cancellation is interpolated, and the carrier observation with a sampling interval of Δt is interpolated to a sampling interval of 1s to construct high sampling rate data, and the high-order difference method is used for multiple difference detection.

[0021] The initial coordinates of the imaging terminal relative to the satellite are calculated using a pseudorange single-point positioning method.

[0022] The process by which the strapdown inertial navigation system acquires and processes data is as follows:

[0023] First, the system is initialized. Then, raw data from the gyroscope, angular velocity meter, magnetometer, and barometer are collected. Error compensation is performed on the raw data. Preliminary attitude information is obtained by using a set proportional error. When the set proportional error is <1, the initial attitude angle is obtained by using the angular velocity meter and magnetometer, and then the initial quaternion is calculated based on the initial attitude angle. When the set proportional error k≥1, the quaternion differential equation is solved using the angular velocity data from the gyroscope, and the attitude angle is obtained as the measured value using the angular velocity meter and magnetometer. Then, the process error covariance and measurement error covariance are calculated to obtain the attitude angle of the shooting terminal.

[0024] A positioning system for a shooting terminal in a strong electromagnetic environment that integrates RTK anti-interference and attitude calculation includes a shooting terminal equipped with a strapdown inertial navigation system and an RTK system. The processor of the shooting terminal is programmed with a computer program for a shooting terminal positioning method in a strong electromagnetic environment that integrates RTK anti-interference and attitude calculation.

[0025] The camera terminal is located in the substation.

[0026] The advantages of this invention compared to existing technologies are as follows: Traditional RTK anti-interference is affected by cycle slip data, resulting in large positioning errors. RTK also lacks attitude perception of the device, only acquiring the target's coordinate information and ignoring spatial attitude information. In contrast, the advantages of this invention are mainly reflected in the following three aspects:

[0027] (1) Strong anti-interference capability. The RTK multipath cancellation-double difference positioning model proposed in this invention effectively solves the multipath effect problem in substations by suppressing direct wave signals and mitigating cycle slip detection problems.

[0028] (2) Strong attitude perception capability. The strapdown inertial navigation system in this invention combines extended Kalman and RTK-assisted calibration to simultaneously acquire the target's position and attitude information, thus achieving multi-information acquisition.

[0029] (3) Strong robustness. The positioning anti-interference method for substation shooting terminals that integrates RTK and spatial attitude calculation proposed in this invention solves the problem of high-precision positioning of equipment by RTK in complex electromagnetic interference environment, and is suitable for positioning tasks in any complex environment. Attached Figure Description

[0030] The present invention will be further described below with reference to the accompanying drawings:

[0031] Figure 1 This is an overall flowchart of the method of the present invention;

[0032] Figure 2 This is a schematic diagram of the RTK multipath cancellation-double difference localization model constructed in this invention;

[0033] Figure 3 This is a flowchart illustrating the data processing of the strapdown inertial navigation system constructed according to the present invention. Detailed Implementation

[0034] like Figures 1 to 3 As shown, this invention addresses the interference problem of RTK positioning and attitude calculation technologies in strong electromagnetic environments. Based on RTK positioning technology and extended Kalman filtering, it combines RTK with an inertial navigation system to propose a positioning method for a shooting terminal in strong electromagnetic environments that integrates RTK anti-interference and attitude calculation. By suppressing electromagnetic interference from buildings and equipment and multipath effects in strong electromagnetic fields, the method improves the accuracy of the device's pose (coordinate information and attitude information). The specific implementation process is as follows: Figure 1 As shown, it includes:

[0035] S1. Construct a strapdown inertial navigation system (SINS) and use sensors such as a 3-axis gyroscope, a 3-axis angular velocity meter, a 3-axis magnetometer, and a barometer to calculate the attitude data of the device.

[0036] S2. Construct an RTK multipath cancellation-dual-difference positioning model. This model integrates multipath suppression and differential positioning techniques. It uses direct wave cancellation technology to eliminate the influence of multipath effects, and then combines dual-difference positioning method to further eliminate other error sources and eliminate multipath effects caused by complex building structures and equipment in substations.

[0037] S3 introduces extended Kalman filtering to fuse RTK positioning data with attitude perception data, and adopts a combined inertial navigation method of strapdown inertial navigation system and RTK-assisted calibration to improve the stability and accuracy of attitude calculation.

[0038] The strapdown inertial navigation system and RTK antenna, among other hardware, are installed into the imaging terminal that needs to be positioned, and the computer program of the method is written into the imaging terminal.

[0039] like Figure 2 The image shows the RTK multipath cancellation-double-difference positioning model proposed in this invention, which is used to eliminate building reflections and electromagnetic interference from the imaging terminal. The model internally includes a reference channel, an FIR filter, and a target echo channel, with a multipath canceller installed in the reference channel.

[0040] The specific implementation steps of this model are as follows:

[0041] S2.1: Constructing a direct wave interference suppression algorithm based on multipath cancellation. By setting a multipath canceller in the reference channel, an adaptive algorithm is used to estimate and eliminate multipath signals, thereby obtaining a purified reference direct wave signal. Then, minimum mean square error (LMS) adaptive filtering is applied to this reference direct wave signal in the target echo channel to suppress direct wave interference. The specific implementation process is as follows:

[0042] Assuming the output signal of the reference channel is y(t), and N is the number of multipath signals, then:

[0043]

[0044] In the formula: s(t) represents the reference direct wave signal, n(t-τ) i ) indicates after different delays τ i And the attenuated multipath leakage signal, α i n(tt) represents the signal amplitude along the corresponding path. i ') represents the cancellation signal, which is achieved by adjusting its delay t. i 'and amplitude α i To match and eliminate leakage signals.

[0045] Based on the above results, the Least Mean Square Error (LMS) algorithm is used for suppression. The calculated reference direct wave signal s(t) is used as a reference signal in the target echo channel to perform adaptive filtering on the target echo signal. By iteratively updating the coefficients of the FIR filter, the error between the output signal of the FIR filter and the desired signal is minimized, thereby suppressing direct wave interference.

[0046] S2.2: RTK Dual-Difference Positioning. Based on multipath cancellation technology, RTK dual-difference positioning is adopted. Through cycle slip detection and repair, positioning deviations generated during signal propagation are suppressed, thereby improving positioning accuracy. The specific implementation process is as follows:

[0047] (1) First, a non-continuous epoch cycle slip detection method is introduced based on the high-order difference method: interruption counting is performed at the epoch where the data is lost. Assuming that the epoch is t1 and the re-acquired epoch is t2, the loss time is Δt = t2 - t1. The sampling interval of the high-order difference method is set to the calculated loss time Δt to ensure equal interval sampling. The original data is interpolated, and the carrier observation value with a sampling interval of Δt is interpolated to a sampling interval of 1s to construct high sampling rate data and ensure observation accuracy. The high-order difference method is used for 4th difference detection.

[0048] (2) Pseudorange single-point positioning provides relatively accurate initial coordinate values ​​for relative positioning, mainly based on the transmission time of satellite signals and the speed of light to calculate the distance between the imaging terminal (receiver) and the satellite.

[0049] (3) Combining observation data from multiple satellites, the current three-dimensional coordinates of the imaging terminal are solved by weighted least squares method.

[0050] Based on the above process, the multipath effect caused by the complex building structure in the substation can be eliminated, and the positioning deviation caused by external interference such as clock error and delay in satellite positioning can be suppressed, thereby further improving the positioning accuracy of RTK.

[0051] This invention utilizes direct wave cancellation technology to eliminate the influence of multipath effects. The multipath canceller identifies and eliminates multipath interference signals that have a fixed delay and amplitude attenuation relationship with the direct wave signal. Simultaneously, it combines RTK dual-difference positioning for real-time differential calculation. For cycle slip deviations generated during propagation, a dual-difference positioning method combined with a high-difference cycle slip recovery strategy is used to detect and correct these deviations. The position is calculated using the dual-difference observations to obtain the precise position information of the imaging terminal.

[0052] like Figure 3 As shown, a strapdown inertial navigation system (SINS) is constructed using a 3-axis gyroscope, a 3-axis angular velocity meter, a 3-axis magnetometer, and a barometer. This system simultaneously measures the attitude, angular velocity, geomagnetic field, and air pressure of the imaging terminal. State equations (calculating attitude angles and velocities) and observation equations (RTK data and state variables) are then constructed. Sensor data is processed by a digital motion processor (DMP) to obtain raw attitude data, such as pitch, roll, and yaw angles, which serve as state variables. Simultaneously, position information, including longitude and latitude data, is received from the RTK system. Position changes are calculated using RTK data to estimate the attitude, which serves as the observation. Finally, an iterative process using an extended Kalman filter algorithm is employed to estimate the real-time attitude of the imaging terminal.

[0053] The data acquisition and processing flow of a strapdown inertial navigation system is as follows: Figure 3 As shown, the system is first initialized, and then raw data from the gyroscope, angular velocity meter, magnetometer, and barometer are collected. Error compensation is performed on the raw data, and preliminary attitude information is solved by setting a proportional error. In this embodiment, the proportional error k is set to 1. When k < 1, the initial attitude angle is solved by the angular velocity meter and magnetometer, and then the initial quaternion is calculated based on the initial attitude angle. When k ≥ 1, the quaternion differential equation is solved using the angular velocity data of the gyroscope, and the attitude angle is solved using the angular velocity meter and magnetometer as the measured value. Then, the process error covariance and measurement error covariance are calculated, and finally, the optimal attitude angle is estimated by Kalman filter attitude fusion.

[0054] This invention integrates RTK positioning technology and extended Kalman filter attitude perception technology. By constructing an RTK multipath cancellation-double-difference positioning model, the multipath effect caused by the complex building structure within the substation is effectively suppressed. Simultaneously, through deep fusion and optimization of positioning and attitude perception data using extended Kalman filtering, the spatial attitude information of the imaging terminal within the substation is further effectively acquired, providing reliable technical support for the precise positioning of substation equipment.

[0055] This invention was integrated into an intelligent image acquisition terminal, which was then placed in the complex natural environment of a substation with strong electromagnetic fields and numerous buildings. The terminal was able to acquire its own latitude and longitude, pitch angle, and yaw angle in real time. The measured horizontal error of the acquired positioning information was 0.035m, and the vertical error was 0.096m.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for positioning a shooting terminal in a strong electromagnetic environment that integrates RTK anti-interference and attitude calculation, characterized in that: Includes the following steps: S1: Construct a strapdown inertial navigation system and use the strapdown inertial navigation system to calculate the attitude data of the shooting terminal in a strong electromagnetic environment; S2: Construct an RTK multipath cancellation-dual-difference positioning model. The model integrates multipath suppression and differential positioning technologies. It uses direct wave cancellation technology to eliminate multipath interference signals that have a fixed delay and amplitude attenuation relationship with the direct wave signal. At the same time, it combines RTK dual-difference positioning to perform real-time differential calculation. It uses dual-difference positioning combined with the high-difference cycle slip recovery strategy to detect and correct cycle slip deviations generated during signal propagation. It uses dual-difference observations to calculate the position and obtain the precise position information of the shooting terminal. S3: An extended Kalman filter is introduced to fuse the RTK positioning data and attitude perception data of the shooting terminal to obtain the final real-time location information of the shooting terminal.

2. The method for positioning a shooting terminal in a strong electromagnetic environment that integrates RTK anti-interference and attitude calculation according to claim 1, characterized in that: The strapdown inertial navigation system includes a 3-axis gyroscope, a 3-axis angular velocity meter, a 3-axis magnetometer, a barometer, and a digital motion processor, which simultaneously measures the attitude, angular velocity, geomagnetic field, and air pressure data of the shooting terminal.

3. The method for positioning a shooting terminal in a strong electromagnetic environment that integrates RTK anti-interference and attitude calculation according to claim 2, characterized in that: The digital motion processor constructs state equations and observation equations to solve and obtain the raw posture data as state variables.

4. The method for positioning a shooting terminal in a strong electromagnetic environment that integrates RTK anti-interference and attitude calculation according to claim 1, characterized in that: The specific implementation process of eliminating multipath interference signals that have a fixed delay and amplitude attenuation relationship with the direct wave signal using direct wave cancellation technology in step S2 is as follows: A multipath canceller is set in the reference channel, and an adaptive algorithm is used to estimate and cancel the multipath signal, thereby obtaining a purified reference direct wave signal. Then, the reference direct wave signal obtained in the previous step is subjected to minimum mean square error (LMS) adaptive filtering in the target channel to suppress direct wave interference.

5. The method for positioning a shooting terminal in a strong electromagnetic environment that integrates RTK anti-interference and attitude calculation according to claim 4, characterized in that: The specific implementation process of detecting and correcting cycle slip deviations generated during signal propagation using the double-difference positioning method combined with the high-difference secondary method cycle slip recovery strategy in step S2 is as follows: First, a discontinuous epoch cycle slip detection method based on the higher order difference method is introduced to preprocess the signal after direct wave cancellation; Then, calculate the initial coordinates of the imaging terminal relative to the satellite; Finally, by combining observation data from multiple satellites, the current three-dimensional coordinates of the imaging terminal are solved using the weighted least squares method.

6. The method for positioning a shooting terminal in a strong electromagnetic environment that integrates RTK anti-interference and attitude calculation according to claim 5, characterized in that: The preprocessing process of the signal after direct wave cancellation is as follows: Based on the higher order difference method, a discontinuous epoch cycle slip detection method is introduced to preprocess the signal using a non-continuous epoch cycle slip detection method. An interruption count is performed at the epoch where the data is lost, assuming that epoch is... t 1. The epoch of recapture is t 2, then the time of loss of lock is Δ t = t 2- t 1; Set the sampling interval of the higher-order difference method to the calculated unlocking time Δ. t Ensure equal-interval sampling; interpolate the signal after direct wave cancellation processing, with a sampling interval of Δ. t The carrier observations are interpolated to a 1-second sampling interval to construct high-sampling-rate data, and multiple difference detections are performed using the high-order difference method.

7. The method for positioning a shooting terminal in a strong electromagnetic environment that integrates RTK anti-interference and attitude calculation according to claim 5, characterized in that: The initial coordinates of the imaging terminal relative to the satellite are calculated using a pseudorange single-point positioning method.

8. The method for positioning a shooting terminal in a strong electromagnetic environment that integrates RTK anti-interference and attitude calculation according to claim 2, characterized in that: The process by which the strapdown inertial navigation system acquires and processes data is as follows: First, the system is initialized. Then, raw data from the gyroscope, angular velocity meter, magnetometer, and barometer are collected. Error compensation is performed on the raw data. Preliminary attitude information is obtained by using a set proportional error. When the set proportional error is <1, the initial attitude angle is obtained by using the angular velocity meter and magnetometer, and then the initial quaternion is calculated based on the initial attitude angle. When the set proportional error k≥1, the quaternion differential equation is solved using the angular velocity data from the gyroscope, and the attitude angle is obtained as the measured value using the angular velocity meter and magnetometer. Then, the process error covariance and measurement error covariance are calculated to obtain the attitude angle of the shooting terminal.

9. A positioning system for a shooting terminal in a strong electromagnetic environment that integrates RTK anti-interference and attitude calculation, characterized in that: The device includes a camera terminal equipped with a strapdown inertial navigation system and an RTK system. The processor of the camera terminal is programmed with a computer program for a camera terminal positioning method in a strong electromagnetic environment that integrates RTK anti-interference and attitude calculation as described in any one of claims 1-8.

10. A positioning system for a shooting terminal in a strong electromagnetic environment that integrates RTK anti-interference and attitude calculation according to claim 9, characterized in that: The camera terminal is located in the substation.

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