Method for improving dynamic adaptability of dynamic-to-dynamic differential positioning

Abstract

The invention discloses a method for improving the dynamic adaptability of motion-to-motion differential positioning, and the method comprises the steps: S1, carrying out the capturing of a satellite navigation signal through employing a method for expanding Doppler capturing frequency deviation under the condition that a carrier moves at a high speed; s2, entering a carrier tracking process and a pseudo code tracking process, and performing carrier phase accumulation in the carrier tracking process; in the pseudo code tracking loop, pseudo code phase accumulation is carried out; outputting a pseudo-range measurement value and a carrier phase measurement value; and S3, carrying out dynamic-to-dynamic differential positioning under a high dynamic condition. According to the method, under the condition that the carrier moves at a high speed, the satellite navigation signal is captured by expanding Doppler capture frequency deviation, and under the condition that the carrier moves at a high speed, the carrier phase cycle slip is detected by using the observed quantity GF combination, so that the positioning error caused by high-speed movement signal distortion is avoided; and the requirement that the carrier carries out motion-to-motion differential positioning under the condition of high-speed motion so as to output an accurate relative position can be met.

Description

Technical Field

[0001] The present invention belongs to the technical field of satellite navigation, and particularly relates to a method for improving the dynamic adaptability of moving-to-moving differential positioning. Background Art

[0002] In actual work, we often need to accurately measure the distance between two carriers to know the distance between them. Commonly used means include laser ranging or radar ranging, but these methods usually have high costs, large volumes, and are inconvenient to use and install.

[0003] Due to cost and installation considerations, the more commonly used method later is to use navigation satellite signals for the moving-to-moving carrier phase differential positioning technology of two carriers. When the two carriers are moving at high speeds respectively, it involves the measurement of the relative distance between the carriers moving under high dynamic conditions. As Figure 2 shown, it includes the following steps: Acquisition of satellite navigation signals under high dynamic conditions: When the carrier is moving at high speed, there will be a large relative speed between the carrier and the navigation satellite. For the carrier, the navigation signal will generate a large Doppler frequency shift relative to the original signal frequency. When acquiring the navigation signal, it is necessary to acquire the navigation signal within a relatively large Doppler frequency shift range. Tracking of satellite navigation signals under high dynamic conditions: After the carrier completes the acquisition of the satellite navigation signal under high dynamic conditions, it is necessary to continue to track the navigation signal to calculate the pseudorange measurement value and carrier phase measurement value in the signal. Moving-to-moving differential positioning under high dynamic conditions: After the carrier performs acquisition and tracking processing on the satellite navigation signal under high dynamic conditions, the original observation information after signal tracking processing is used for moving-to-moving differential positioning.

[0004] In the prior art, the application scenarios of moving-to-moving differential positioning are basically scenarios with slow speed changes. When the carrier needs to work under high-speed operating conditions, conventional moving-to-moving differential positioning cannot perform normal positioning calculations. Since the carrier needs to operate at a relatively high speed, there will be a large relative speed with respect to the navigation satellite. The relative speed will cause the satellite navigation signal to generate a large signal frequency shift relative to the carrier. Therefore, a conventional receiver cannot normally acquire and track a signal with a large frequency shift. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for improving the dynamic adaptability of moving-to-moving differential positioning in view of the above deficiencies in the prior art. Under the condition that the carrier is operating at high speed, it can normally acquire, process, and track the navigation satellite signal, and perform moving-to-moving differential positioning, and the accuracy meets the usage requirements.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is: a method for improving the dynamic adaptability of moving-to-moving differential positioning, the method comprising the following steps: Step S1, when the carrier is moving at high speed, the method of expanding the Doppler capture frequency offset is used to capture satellite navigation signals; Step S2, entering the carrier tracking and pseudo-code tracking processes. During the carrier tracking process, carrier phase accumulation is performed; in the pseudo-code tracking loop, pseudo-code phase accumulation is performed; pseudo-range measurement values and carrier phase measurement values are output; Step S3, after performing data preprocessing of cycle slip detection and gross error rejection on the pseudo-range measurement values and carrier phase measurement values, moving-to-moving differential positioning is performed under high dynamic conditions.

[0007] For the above method for improving the dynamic adaptability of moving-to-moving differential positioning, in Step S1, when the carrier is moving at high speed, the specific process of using the method of expanding the Doppler capture frequency offset to capture satellite navigation signals is as follows: Step S101, assign a value to the capturer with a Doppler frequency offset value of , perform a capture operation. When the capture is successful, execute Step S104; when the capture fails, execute Step S102; Step S102, assign a value to the capturer with a Doppler frequency offset value increased by , perform a capture operation. When the capture is successful, execute Step S104; when the capture fails, execute Step S103; Step S103, assign a value to the capturer with a Doppler frequency offset value increased by to perform a capture operation. When the capture is successful, execute Step S104; when the capture fails, return to execute Step S102; Step S104, perform tracking processing. For the above method for improving the dynamic adaptability of moving-to-moving differential positioning, in Steps S101 to S103 the value of

[0008] is 1 kHz.

[0009] For the above method for improving the dynamic adaptability of moving-to-moving differential positioning, when performing cycle slip detection and gross error rejection on the pseudo-range measurement values and carrier phase measurement values in Step S3, the GF (geometry-free) combination method is used. , where, is the difference between the pseudo-range measurement values and of two adjacent epochs, is the difference between the carrier phase measurement values of two adjacent epochs and taking the difference; Step A2: After the GF combination of the dual-frequency pseudorange ionospheric residual model and the dual-frequency carrier phase ionospheric model, it is , expressed as: , where is the polynomial generated after the order polynomial fitting, equivalent to , expressed as: , where is the wavelength of frequency 1, is the integer ambiguity of frequency 1, is the wavelength of frequency 2, is the integer ambiguity of frequency 2; Step A3: By taking the difference of between two adjacent epochs, the cycle slip and gross error of the satellite navigation signal carrier phase measurement value are determined.

[0010] For the above method for improving the dynamic adaptability of kinematic-to-kinematic differential positioning, when determining the cycle slip and gross error of the satellite navigation signal carrier phase measurement value by taking the difference of between two adjacent epochs in Step A3, it is expressed by the formula: , where and are both constant coefficients; in cycle slip detection, when both Equation (F5) and Equation (F6) hold simultaneously, it is determined that the cycle slip phenomenon occurs in the satellite signal participating in the solution currently; when only Equation (F5) is satisfied, it is determined that there is a gross error in the measurement of the current satellite signal; when it is determined that there is a gross error or a cycle slip in the measurement of the current satellite signal, it is selected to exclude the current satellite signal from the solution process and continue the solution using the remaining satellite signals.

[0011] For the above method for improving the dynamic adaptability of kinematic-to-kinematic differential positioning, the value of is 6.

[0012] For the above method for improving the dynamic adaptability of kinematic-to-kinematic differential positioning, the value of is 1.

[0013] The above method for improving the dynamic adaptability of moving-to-moving differential positioning. In step S3, when performing moving-to-moving differential positioning under high dynamic conditions, the specific process is as follows: Step S301, establish a carrier relative positioning mathematical model and establish a pseudorange relative positioning mathematical model; Step S302, perform filtering parameter estimation on both the carrier relative positioning mathematical model and the pseudorange relative positioning mathematical model; Step S303, perform ambiguity fixing on the carrier relative positioning mathematical model to obtain a fixed solution; Step S304, perform residual check on the carrier relative positioning mathematical model and the pseudorange relative positioning mathematical model. When the check passes, output the result. When the check fails, return to step S301. In the above method for improving the dynamic adaptability of moving-to-moving differential positioning, when performing filtering parameter estimation in step S303, the Kalman filtering parameter estimation method is adopted.

[0014] Compared with the prior art, the present invention has the following advantages: Under the condition that the carrier moves at a high speed, the present invention uses the expanded Doppler capture frequency offset to capture satellite navigation signals. Under the condition that the carrier moves at a high speed, the GF combination of observables is used to detect the carrier phase cycle slips, thereby avoiding positioning errors caused by signal distortion during high-speed movement, and can meet the requirement of performing moving-to-moving differential positioning when the carrier moves at a high speed and outputting accurate relative positions.

[0015] Next, through the drawings and embodiments, the technical solution of the present invention will be further described in detail. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a flowchart of the method of the present invention; Figure 2 It is a flowchart of moving-to-moving differential positioning under high dynamic conditions of the present invention; Figure 3 It is a flowchart of capturing satellite navigation signals of the present invention; Figure 4 It is a processing diagram of the Doppler frequency offset of satellite navigation signals when the carrier has a large speed in the present invention; Figure 5 It is a schematic diagram of the satellite navigation signal tracking loop of the present invention; Figure 6 It is a flowchart of moving-to-moving differential positioning calculation of the present invention; Figure 7 It is a flowchart of carrier phase signal cycle slip detection of the present invention; Figure 8 It is a graph of the measurement accuracy of the baseline length between two carriers on the X-axis, Y-axis, and Z-axis of the present invention; Figure 9 It is a graph of the combined measurement accuracy of the baseline length between two carriers on the three axes of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] As Figure 1As shown, the method for improving the dynamic adaptability of dynamic-to-dynamic differential positioning of the present invention includes the following steps: Step S1, when the carrier is moving at high speed, the method of expanding the Doppler capture frequency offset is used to capture satellite navigation signals; when performing capture processing on satellite navigation signals under high dynamic conditions, by expanding the frequency search range of the satellite navigation signals to be captured, the capture of signals by the carrier under high-speed movement conditions is achieved; as Figure 3 shown; where the key step is to search again for the signal generating the Doppler frequency offset in the next frequency domain range. During the capture process of satellite navigation signals, special processing needs to be performed on high-speed movement scenarios. When the carrier is moving at low speed, it is not necessary to capture signals with a large capture frequency offset, but when the carrier is moving at high speed, it is necessary to capture signals with a large Doppler frequency offset.

[0018] In this embodiment, the specific process of using the method of expanding the Doppler capture frequency offset to capture satellite navigation signals in Step S1 when the carrier is moving at high speed is as follows: Step S101, assign a value to the capture device with a Doppler frequency offset value of , perform a capture operation, and when the capture is successful, execute Step S104; when the capture fails, execute Step S102; Step S102, assign a value to the capture device with the Doppler frequency offset value increased by , perform a capture operation, and when the capture is successful, execute Step S104; when the capture fails, execute Step S103; Step S103, assign a value to the capture device with the Doppler frequency offset value increased by , perform a capture operation, and when the capture is successful, execute Step S104; when the capture fails, return to execute Step S102; Step S104, perform tracking processing. In this embodiment, the value of in Steps S101 to S103 is 1 kHz.

[0019] Taking the capture of the No. 1 satellite navigation signal moving at high speed as an example, as Figure 4As shown in the figure, the specific process of capturing satellite navigation signals by using the method of expanding the Doppler capture frequency offset is as follows: Step S101: Assign the Doppler frequency offset value of 1 kHz of the satellite navigation signal of satellite No. 1 to the capturer, and capture the satellite navigation signal of satellite No. 1. When the capture is successful, execute step S104; when the capture fails, execute step S102; Step S102: Assign the Doppler frequency offset value of the satellite navigation signal of satellite No. 1 increased by 1 kHz to the capturer, and capture the satellite navigation signal of satellite No. 1. When the capture is successful, execute step S104; when the capture fails, execute step S103; Step S103: Assign the Doppler frequency offset value of the satellite navigation signal of satellite No. 1 increased by 1 kHz to the capturer, and capture the satellite navigation signal of satellite No. 1. When the capture is successful, execute step S104; when the capture fails, return to execute step S102; Step S104: Track the satellite navigation signal of satellite No. 1.

[0020] When specifically implemented, when the maximum capture Doppler frequency offset is set to 6 kHz, the maximum moving speed of the carrier can be satisfied to be 7000 m / s.

[0021] Step S2: After signal capture, enter the carrier tracking and pseudo-code tracking process. As Figure 5 shown, use the Doppler frequency pre-estimation value and pseudo-code phase pre-estimation value output by the capture module to quickly set the carrier NCO and code NCO, so that the tracking channel quickly enters the carrier tracking and pseudo-code tracking process. During the carrier tracking process, perform carrier phase accumulation; in the pseudo-code tracking loop, perform pseudo-code phase accumulation; when the loop is locked, perform bit synchronization, frame synchronization clock extraction of data, and output the pseudo-range measurement value and carrier phase measurement value; Step S3: As Figure 6 shown, after performing data preprocessing of cycle slip detection and gross error rejection on the pseudo-range measurement value and carrier phase measurement value, perform dynamic-to-dynamic differential positioning under high dynamic conditions. In this embodiment, when performing cycle slip detection and gross error rejection on the pseudo-range measurement value and carrier phase measurement value in step S3, the GF (geometry-free) combination method is used.

[0022] In this embodiment, the specific process of using the GF (geometry-free) combination method to perform cycle slip detection and gross error rejection on the pseudo-range measurement value and carrier phase measurement value in step S3 is as follows: Step A1: Establish a dual-frequency pseudo-range ionospheric residual model and a dual-frequency carrier phase ionospheric residual model, expressed as: , where is the difference between the pseudo-range measurement values of two adjacent epochs and do the difference, is the difference between the carrier phase measurement values of two adjacent epochs and Take the difference; Step A2: After the GF combination of the dual-frequency pseudorange ionospheric residual model and the dual-frequency carrier phase ionospheric model, it is , expressed as: , where, is the polynomial generated after performing order polynomial fitting, equivalent to , expressed as: , where, is the wavelength of frequency 1, is the integer ambiguity of frequency 1, is the wavelength of frequency 2, is the integer ambiguity of frequency 2; Step A3: By taking the difference of between two adjacent epochs, determine the cycle slips and gross errors of the satellite navigation signal carrier phase measurement values.

[0023] In this embodiment, when determining the cycle slips and gross errors of the satellite navigation signal carrier phase measurement values by taking the difference of between two adjacent epochs in Step A3, it is expressed by the formula: , where, represents the th epoch, represents the th epoch, represents the th epoch, and are both constant coefficients.

[0024] In cycle slip detection, when both Equation (F5) and Equation (F6) hold simultaneously, it is determined that a cycle slip phenomenon occurs in the satellite signal currently participating in the solution; when only Equation (F5) is satisfied, it is determined that a gross error occurs in the current satellite signal measurement; when it is determined that a gross error or a cycle slip occurs in the measurement of the current satellite signal, select to exclude the current satellite signal from the solution process and continue the solution using the remaining satellite signals; the judgment process is as Figure 7 shown.

[0025] In this embodiment, the value of is 6. That is, Equation (F5) is expressed as: .

[0026] In this embodiment, the value of is 1. That is, Equation (F6) is expressed as: 。

[0027] In this embodiment, the process of performing moving-to-moving differential positioning under high-dynamic conditions in step S3 is as follows: Step S301: Establish a carrier relative positioning mathematical model and establish a pseudorange relative positioning mathematical model; Step S302: Perform filtering parameter estimation on both the carrier relative positioning mathematical model and the pseudorange relative positioning mathematical model; Step S303: Fix the ambiguity of the carrier relative positioning mathematical model to obtain a fixed solution; Step S304: Perform residual check on the carrier relative positioning mathematical model and the pseudorange relative positioning mathematical model. When the check passes, output the result. When the check fails, return to step S301.

[0028] Using the moving-to-moving differential positioning technology, two devices serve as the reference station and the mobile station for each other. After the reference station calculates its own position through the pseudorange, it sends this coordinate as the reference station coordinate to the mobile station. Since the carrier is in a high-speed motion state, phenomena such as signal interruption, signal loss of lock, and signal distortion may occur in the satellite navigation signal. When the lost signal is captured again, cycle slips may occur. When cycle slips occur, special processing is required to eliminate the influence of cycle slips on differential positioning; In the case of high-speed movement of the carrier, the present invention uses the observable GF combination to detect the carrier phase cycle slips, which can effectively avoid positioning errors caused by signal distortion during high-speed movement.

[0029] Step S302: Establish a carrier relative positioning mathematical model and establish a pseudorange relative positioning mathematical model; Step S303: Perform filtering parameter estimation on both the carrier relative positioning mathematical model and the pseudorange relative positioning mathematical model. In this embodiment, when performing filtering parameter estimation in step S303, the Kalman filtering parameter estimation method is used. Step S304: Fix the ambiguity of the carrier relative positioning mathematical model to obtain a fixed solution; Step S305: Perform residual check on the carrier relative positioning mathematical model and the pseudorange relative positioning mathematical model. When the check passes, output the result. When the check fails, return to step S301.

[0030] To verify the technical effects that the present invention can produce, a navigation signal source is used to simulate moving-to-moving differential positioning of two carriers under high-speed movement, and the measured relative distance is subtracted from the relative distance reference of the simulation source to obtain the baseline measurement accuracy; the satellite navigation simulation source sets the test scenario as two carriers with speeds of 7000 m / s respectively, the distance between the two carriers is 24 km, and the broadcast signals are BDS B1 signal and BDS B3 signal; the test results are as Figure 8 and Figure 9 shown. It is found through the test results that the three-axis combined error of the measured relative distance is 0.036 m (1σ), which meets the requirements of moving-to-moving differential positioning of the carrier at high speed.

[0031] The above are only the preferred embodiments of the present invention, and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent structural changes made to the above embodiments based on the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for improving the dynamic adaptability of dynamic-to-dynamic differential positioning, characterized in that: The method comprises the following steps: step S1, when the carrier moves at high speed, a method of expanding Doppler capture frequency offset is adopted to capture satellite navigation signals; step S2, entering the carrier tracking and pseudo code tracking process, during which carrier phase accumulation is performed; in the pseudo code tracking loop, pseudo code phase accumulation is performed; pseudo range measurement values ​​and carrier phase measurement values ​​are output; step S3, after data preprocessing of cycle slip detection and gross error elimination is performed on the pseudo range measurement values ​​and the carrier phase measurement values, dynamic-to-dynamic differential positioning is performed under high dynamic conditions.

2. A method for improving dynamic adaptability of dynamic-to-dynamic differential positioning according to claim 1, characterized in that: The specific process of capturing satellite navigation signals by using the method of expanding the Doppler capture frequency offset in step S1 when the carrier moves at high speed is as follows: step S101, assigning a value to the capture device with the Doppler frequency offset value as , perform the capture operation, if the capture is successful, execute step S104; if the capture fails, execute step S102; step S102, assign a value to the capture device to increase the Doppler frequency deviation value , perform the capture operation, if the capture is successful, execute step S104; if the capture fails, execute step S103; step S103, assign a value to the capture device to increase the Doppler frequency deviation value , perform a capture operation, when the capture is successful, execute step S104; when the capture fails, return to execute step S102; step S104, tracking processing.

3. A method for improving dynamic adaptability of dynamic-to-dynamic differential positioning according to claim 2, characterized in that: In step S101 to step S103 The value is 1kHz.

4. A method for improving dynamic adaptability of dynamic-to-dynamic differential positioning according to claim 1, characterized in that: When performing cycle slip detection and gross error elimination on the pseudorange measurement value and the carrier phase measurement value in step S3, the GF combination method is used.

5. A method for improving dynamic adaptability of dynamic-to-dynamic differential positioning according to claim 4, characterized in that: When performing cycle slip detection and gross error elimination on the pseudorange measurement value and the carrier phase measurement value in step S3, the specific process of using the GF combination method is as follows: Step A1, establishing a dual-frequency pseudorange ionosphere residual model and a dual-frequency carrier phase ionosphere residual model, expressed as: , in, is the pseudorange measurement value of two adjacent epochs and Do badly, is the phase measurement value of two adjacent carriers and Step A2, the dual-frequency pseudo-range ionosphere residual model and the dual-frequency carrier phase ionosphere model are combined by GF to obtain , expressed as: ,in, for The polynomial generated after performing N-order polynomial fitting, Equivalent to , expressed as: in, is the wavelength of frequency 1, is the integer ambiguity of frequency 1, is the wavelength of frequency 2, is the integer ambiguity of frequency 2; Step A3, through the two adjacent epochs Make a difference and determine the cycle slip and gross error of the satellite navigation signal carrier phase measurement value.

6. A method for improving dynamic adaptability of dynamic-to-dynamic differential positioning according to claim 5, characterized in that: Step A3 describes the process of When making a difference and determining the cycle slip and gross error of the satellite navigation signal carrier phase measurement value, the formula is: ,in, and are all constant coefficients; in cycle slip detection, when equation (F5) and equation (F6) are both established, it is determined that the satellite signal currently involved in the solution has a cycle slip; when only equation (F5) is satisfied, it is determined that a gross error has occurred in the measurement of the current satellite signal; when it is determined that a gross error or a cycle slip has occurred in the measurement of the current satellite signal, the current satellite signal is selected to be removed from the solution process, and the remaining satellite signals are used to continue the solution.

7. A method for improving dynamic adaptability of dynamic-to-dynamic differential positioning according to claim 6, characterized in that: Said The value of is 6.

8. A method for improving dynamic adaptability of dynamic-to-dynamic differential positioning according to claim 6, characterized in that: Said The value of is 1.

9. A method for improving dynamic adaptability of dynamic-to-dynamic differential positioning according to claim 1, characterized in that: The specific process of performing dynamic-to-dynamic differential positioning under high dynamic conditions as described in step S3 is as follows: step S301, establishing a carrier relative positioning mathematical model, and establishing a pseudorange relative positioning mathematical model; step S302, estimating filter parameters for both the carrier relative positioning mathematical model and the pseudorange relative positioning mathematical model; step S303, fixing the ambiguity of the carrier relative positioning mathematical model to obtain a fixed solution; step S304, performing residual check on the carrier relative positioning mathematical model and the pseudorange relative positioning mathematical model, and outputting the result when the check passes, and returning to step S301 when the check fails.

10. A method for improving dynamic adaptability of dynamic-to-dynamic differential positioning according to claim 9, characterized in that: When estimating the filter parameters in step S303, a Kalman filter parameter estimation method is used.

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