A positioning and navigation method based on dual-carrier phase differential mobile station

Abstract

The invention discloses a positioning and navigation method based on a dual-carrier phase differential mobile station, and relates to the technical field of positioning and navigation. In the method, two RTK mobile stations are arranged on an automatic guided vehicle (AGV); satellite positioning is used to obtain the GPS positions of a first mobile station, a second mobile station and a base station respectively; a local coordinate system is established with the base station as the origin, and the position coordinates (x1(k), y1(k)) of the first mobile station in the local coordinate system and the position coordinates (x2(k), y2(k)) of the second mobile station in the local coordinate system are obtained; the heading angle θ(k) of the automatic guided vehicle (AGV) at the kth sampling moment is calculated; the center of mass coordinates (x(k), y(k)) of the automatic guided vehicle (AGV) at the kth sampling moment are calculated; the position coordinates (X(k), Y(k)) of the automatic guided vehicle (AGV) in the local coordinate system at the kth sampling moment are calculated, and the actual physical posture (X(k), Y(k), θ(k)) of the automatic guided vehicle (AGV) in the local coordinate system at the kth sampling moment is obtained. The positioning and navigation method of the present invention has the characteristics of high flexibility, high accuracy and high real-time performance, and improves the positioning efficiency and the diversity of AGV application scenarios.

Description

Technical Field

[0001] The invention relates to the technical field of positioning and navigation, and in particular to a positioning and navigation method based on a dual-carrier phase differential mobile station. Background Art

[0002] With the advancement of science and technology, physical manufacturing factories are gradually turning to intelligent and unmanned operations. Automated Guided Vehicles (AGVs), as an intelligent industrial equipment, are widely used in various industries. Navigation and positioning technology is the basis of AGV autonomous movement. Currently, the navigation and positioning methods used for outdoor AGVs include magnetic navigation, visual navigation, and global positioning system (GPS) navigation. Magnetic navigation requires laying magnetic strips, and the layout of magnetic strips is affected by the environment, which brings a lot of inconvenience. Visual navigation is difficult to develop and is easily affected by light outdoors, resulting in inaccurate positioning. GPS navigation technology has been widely used in land, ocean, space navigation and positioning and other fields due to its free path change, simple implementation in open outdoor places, and convenient team command and monitoring combined with digital maps.

[0003] GPS navigation positioning errors are affected by many factors, including satellite errors, propagation errors, reception errors, etc. Carrier phase differential (RTK) is a real-time differential measurement technology that uses carrier phase as the basic observation quantity. A base station is set up near the mobile station. The base station is equipped with a high-precision positioning instrument and communicates with GPS satellites simultaneously and continuously with the mobile station. The base station sends its observation values, station coordinates, satellite tracking status, etc. to the mobile station through a data link. The mobile station solves the carrier phase integer ambiguity, and then obtains the error of the mobile station through the relative positioning model, and this error is used to correct the spatial position data of the mobile station. Carrier phase differential GPS can effectively eliminate or weaken the influence of ephemeris error, satellite clock error, ionospheric delay error, tropospheric delay error and random noise error, thereby obtaining centimeter-level navigation positioning accuracy.

[0004] In the existing technology, a single RTK positioning technology is used outdoors to provide angle data, and the real-time positioning will have obvious deficiencies. Especially during the rotation of the AGV, the angle calculation module inside the RTK is greatly affected by the positioning error. If the longitude and latitude values ​​fluctuate slightly, the angle value will easily jump, resulting in positioning stability and real-time performance that are difficult to meet the chassis motion control and other task development requirements. Summary of the invention

[0005] In order to overcome the defects in the above-mentioned prior art, the present invention provides a positioning and navigation method based on a dual-carrier phase differential mobile station, which has the characteristics of high flexibility, high precision and high real-time performance, improves the positioning efficiency and the diversity of AGV application scenarios.

[0006] To achieve the above object, the present invention adopts the following technical solutions, including:

[0007] A positioning and navigation method based on a dual-carrier phase differential mobile station comprises the following steps:

[0008] S1, arrange two RTK mobile stations on the automatic guided vehicle AGV, namely the first mobile station and the second mobile station;

[0009] S2, performing the k-th acquisition using satellite positioning, and obtaining the GPS positions of the first mobile station, the second mobile station, and the base station at the k-th sampling time, respectively, wherein the GPS positions include accuracy and latitude;

[0010] Among them, the longitude of the first mobile station at the kth sampling time is lon1(k), and the latitude is lat1(k); the longitude of the second mobile station at the kth sampling time is lon2(k), and the latitude is lat2(k); the longitude of the base station at the kth sampling time is baselon(k), and the latitude is baselat(k);

[0011] S3, establish a local coordinate system with the base station as the origin, and obtain the position coordinates (x1(k), y1(k)) of the first mobile station in the local coordinate system and the position coordinates (x2(k), y2(k)) of the second mobile station in the local coordinate system at the kth sampling time according to the GPS positions of the first mobile station, the second mobile station, and the base station at the kth sampling time;

[0012] S4, according to the GPS positions of the first mobile station and the second mobile station at the kth sampling time, calculate the heading angle θ(k) of the automatic guided vehicle AGV at the kth sampling time, θ(k)∈[0°,360°];

[0013] S5, calculate the center of mass coordinates (x(k), y(k)) of the automatic guided vehicle AGV at the kth sampling moment according to the position coordinates (x1(k), y1(k)) of the first mobile station in the local coordinate system and the position coordinates (x2(k), y2(k)) of the second mobile station in the local coordinate system at the kth sampling moment;

[0014] S6, based on the center of mass coordinates (x(k), y(k)) of the AGV at the kth sampling moment, calculate the position coordinates (X(k), Y(k)) of the automatic guided vehicle AGV in the local coordinate system at the kth sampling moment, and obtain the actual physical posture (X(k), Y(k), θ(k)) of the automatic guided vehicle AGV in the local coordinate system at the kth sampling moment.

[0015] Preferably, in step S1, the two RTK mobile stations are arranged on the front and rear sides of the automatic guided vehicle AGV respectively, and the centers of the two RTK mobile stations are on the same straight line.

[0016] Preferably, in step S4, the calculation method of the heading angle θ(k) of the automatic guided vehicle AGV at the k-th sampling moment is as follows:

[0017] S41. Determine whether the longitude lon1(k) of the first mobile station and the longitude lon2(k) of the second mobile station are equal at the k-th sampling moment. If they are not equal, go to step S42; otherwise, go to step S43;

[0018] S42. If lon1(k)>lon2(k) and lat1(k)≥lat2(k), calculate the latitude difference Δlat(k) and the longitude difference Δlon(k) of the two RTK mobile stations at the k-th sampling moment, Δlat(k)=lat1(k)-lat2(k), Δlon(k)=lon1(k)-lon2(k), and take the arctangent value of the ratio of Δlat to Δlon as the heading angle θ(k) of the AGV at the k-th sampling moment;

[0019] If lon1(k)>lon2(k) and lat1(k)<lat2(k), calculate the latitude difference Δlat(k) and the longitude difference Δlon(k) of the two RTK mobile stations at the k-th sampling moment, Δlat(k)=lat1(k)-lat2(k), Δlon(k)=lon1(k)-lon2(k), and take the absolute value of the arctangent value of the ratio of Δlat to Δlon minus 360° as the heading angle θ(k) of the AGV at the k-th sampling moment;

[0020] If lon1(k)<lon2(k) and lat1(k)≥lat2(k), calculate the latitude difference Δlat(k) and the longitude difference Δlon(k) of the two RTK mobile stations at the k-th sampling moment, Δlat(k)=lat1(k)-lat2(k), Δlon(k)=lon1(k)-lon2(k), and take the absolute value of the arctangent value of the ratio of Δlat to Δlon minus 180° as the heading angle θ(k) of the AGV at the k-th sampling moment;

[0021] If lon1(k)<lon2(k) and lat1(k)<lat2(k), calculate the latitude difference Δlat(k) and the longitude difference Δlon(k) of the two RTK mobile stations at the k-th sampling moment, Δlat(k)=lat1(k)-lat2(k), Δlon(k)=lon1(k)-lon2(k), and take the value of the arctangent value of the ratio of Δlat to Δlon plus 180° as the heading angle θ(k) of the AGV at the k-th sampling moment;

[0022] In S43, if lon1(k) = lon2(k) and lat1(k) > lat2(k), then the heading angle θ(k) of the AGV at the k-th sampling moment is 90°;

[0023] If lon1(k) = lon2(k) and lat1(k) < lat2(k), then the heading angle θ(k) of the AGV at the k-th sampling moment is 270°.

[0024] Preferably, in step S3, based on the difference between the GPS positions of the first mobile station and the base station at the k-th sampling moment, the position coordinates (x1(k), y1(k)) of the first mobile station in the local coordinate system at the k-th sampling moment are obtained; based on the difference between the GPS positions of the second mobile station and the base station at the k-th sampling moment, the position coordinates (x2(k), y2(k)) of the second mobile station in the local coordinate system at the k-th sampling moment are obtained.

[0025] Preferably, in step S5, the calculation method of the centroid coordinates (x(k), y(k)) of the automatic guided vehicle AGV at the k-th sampling moment is as follows:

[0026] x(k) = [x1(k) + x2(k)] / 2;

[0027] y(k) = [y1(k) + y2(k)] / 2.

[0028] Preferably, in step S6, the calculation method of the position coordinates (X(k), Y(k)) of the automatic guided vehicle AGV in the local coordinate system at the k-th sampling moment is as follows:

[0029] X(k) = C lon ·x(k), Y(k) = C lat ·y(k);

[0030] where C lon is the longitude physical distance conversion coefficient, and C lat is the latitude physical distance conversion coefficient.

[0031] Preferably, the calibration method of the physical distance conversion coefficient is as follows:

[0032] During the calibration process, the RTK mobile station and the base station maintain a certain distance or more;

[0033] For the calibration of the longitude physical distance conversion coefficient C lon : First, measure an x-axis distance segment with an actual physical distance of α meters along the x-axis direction, then place the RTK mobile station at both ends of the x-axis distance segment for positioning to obtain the longitude difference of the RTK mobile station at both ends of the distance segment, and finally divide α meters by the longitude difference to obtain the ratio, which is C lon .

[0034] For latitude physical distance conversion factor C lat To calibrate, first measure a y-axis distance segment with an actual physical distance of α meters along the y-axis direction, then place the RTK mobile station at both ends of the y-axis distance segment for positioning, so as to obtain the latitude difference of the RTK mobile station at both ends of the distance segment, and finally divide α meters by the latitude difference to obtain the ratio, which is C lat .

[0035] Preferably, during the calibration process, the RTK mobile station and the base station are kept at a distance of more than 5 meters.

[0036] Preferably, the positioning and navigation method is applied to a global real-time positioning system consisting of two RTK mobile stations, n satellites and a base station.

[0037] Preferably, n≥8.

[0038] The advantages of the present invention are:

[0039] (1) The present invention proposes a positioning and navigation method based on a dual RTK mobile station with high flexibility, high precision and high real-time performance, which can achieve centimeter-level global positioning, improve positioning efficiency and the diversity of AGV application scenarios.

[0040] (2) The dual RTK mobile station positioning and navigation method proposed in the present invention can ensure high-precision latitude and longitude information and heading angles over long distances (at least 5 kilometers) outdoors, thereby improving the applicability of AGV in special outdoor scenarios.

[0041] (3) Compared with the magnetic navigation in the prior art that requires the deployment of magnetic strips, the hardware deployment of the dual RTK mobile station of the present invention is much simpler and more convenient, and can ensure the positioning accuracy of the AGV.

[0042] (4) The arrangement method of dual RTK mobile stations: Since the front and rear RTK mobile stations are separated by a certain distance, the longitude and latitude positioning errors have little effect on the angle calculation, making the angle value calculated based on the coordinates more stable, ensuring real-time performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The present invention is a flow chart of a positioning and navigation method based on a dual-carrier phase differential mobile station.

[0044] Figure 2 This is a schematic diagram of the RTK mobile station positioning principle of the present invention.

[0045] Figure 3 A local coordinate system diagram established for the present invention. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] In this embodiment, a positioning and navigation method based on a dual-carrier phase differential mobile station is applied to a global real-time positioning system consisting of two RTK mobile stations, n satellites and a base station, where n≥8; the two RTK mobile stations are respectively arranged at the front and rear positions of the top of the AGV, and the centers of the two RTK mobile stations are in the same straight line. The base station is a device fixed on the ground to provide a reference benchmark for the mobile station and cannot be moved during use; the mobile station is an operating device, which uses the differential data sent from the fixed station for RTK precise positioning. There should be no obstructions above the mobile station to avoid affecting communication with the base station. The base station should be arranged in an open area, with as few tall buildings as possible nearby;

[0048] Depend on Figure 1 As shown, the positioning and navigation method is performed in the following steps:

[0049] S1, two RTK mobile stations are arranged on the automatic guided vehicle AGV, namely the first mobile station and the second mobile station.

[0050] The two RTK mobile stations are correspondingly arranged on the front and rear sides of the automatic guided vehicle AGV, and the centers of the two RTK mobile stations are on the same straight line.

[0051] S2, use satellite positioning to perform the k-th collection, and obtain the GPS positions of the first mobile station, the second mobile station, and the base station at the k-th sampling moment, respectively, and the GPS positions include accuracy and latitude; wherein, the longitude of the first mobile station at the k-th sampling moment is lon1(k), and the latitude is lat1(k); the longitude of the second mobile station at the k-th sampling moment is lon2(k), and the latitude is lat2(k); the longitude of the base station at the k-th sampling moment is baselon(k), and the latitude is baselat(k).

[0052] The principle of GPS satellite navigation positioning is as follows Figure 2 shown.

[0053] The GPS satellite navigation positioning process is based on the passive ranging principle, that is, the mobile station passively measures the propagation delay of the navigation positioning signal from the GPS satellite, and measures the phase center of the GPS satellite transmitting antenna and the phase center of the mobile station GPS signal receiving antenna (x s ,y s ,zs ) (i.e., the station-satellite distance), due to the clock deviation δt between the mobile station and GPS time (derived from the atomic clock on the satellite) s , so the measured station-satellite distance is an inaccurate pseudo-range. Figure 2 As shown, if n satellites are observed simultaneously, then:

[0054] (P i -cδt n ) 2 =(x i -x s ) 2 +(y i -y s ) 2 +(z i -z s ) 2

[0055] Among them, P i is the pseudo-range measurement value between satellite i and mobile station, (x i ,y i ,z i ) is the three-dimensional position of the ith satellite, c is the speed of light (3×10 8 m / s). In order to determine the four unknown quantities (x s ,y s ,z s ,δt s ) requires four equations to be solved, so in order to obtain the spatial position of a mobile station, it is necessary to simultaneously interact with at least four satellites to obtain a set of four-variable quadratic equations. After solving them, the spatial position of the mobile station, namely the GPS position, can be obtained.

[0056] However, GPS navigation positioning errors are also affected by many factors, including propagation delay caused by the ionosphere, propagation delay caused by the troposphere, multipath error, etc. Considering the impact of various errors on pseudorange measurement, the pseudorange measurement value between satellite i and the mobile station is corrected to:

[0057] (P i -cδt n -I i (t)-T i (t)-ε i (t)) 2 =(x i -x s ) 2 +(y i -y s ) 2 +(z i -z s ) 2

[0058] Among them, I i (t) represents the propagation delay correction value of the i-th satellite caused by the ionosphere, T i (t) represents the propagation delay correction value of the ith satellite due to the troposphere, ε i (t) represents the ranging error correction value caused by other reasons of the i-th satellite. Error correction is achieved using RTK technology.

[0059] S3, with the base station as the origin, the east direction as the X axis, and the north direction as the Y axis, establish a local coordinate system, such as Figure 3 As shown, according to the GPS positions of the first mobile station, the second mobile station and the base station at the kth sampling moment, the position coordinates (x1(k), y1(k)) of the first mobile station in the local coordinate system and the position coordinates (x2(k), y2(k)) of the second mobile station in the local coordinate system at the kth sampling moment are obtained.

[0060] Among them, according to the difference between the GPS positions of the first mobile station and the base station at the kth sampling moment, the position coordinates (x1(k), y1(k)) of the first mobile station in the local coordinate system at the kth sampling moment are obtained; according to the difference between the GPS positions of the second mobile station and the base station at the kth sampling moment, the position coordinates (x2(k), y2(k)) of the second mobile station in the local coordinate system at the kth sampling moment are obtained.

[0061] S4, according to the GPS positions of the first mobile station and the second mobile station at the kth sampling time, calculate the heading angle θ(k) of the automatic guided vehicle AGV at the kth sampling time, θ(k)∈[0°,360°].

[0062] The calculation method of the heading angle θ(k) of the automatic guided vehicle AGV at the kth sampling time is as follows:

[0063] S41, determining whether the longitude lon1(k) of the first mobile station and the longitude lon2(k) of the second mobile station at the kth sampling time are equal, if not, proceeding to step S42, otherwise proceeding to step S43;

[0064] S42, if lon1(k)>lon2(k), and lat1(k)≥lat2(k), then calculate the latitude difference Δlat(k) and longitude difference Δlon(k) of the two RTK mobile stations at the kth sampling time, Δlat(k)=lat1(k)-lat2(k), Δlon(k)=lon1(k)-lon2(k), and take the arc tangent value of the ratio of Δlat and Δlon as the heading angle θ(k) of the AGV at the kth sampling time;

[0065] If lon1(k) > lon2(k) and lat1(k) < lat2(k), then calculate the latitude difference Δlat(k) and longitude difference Δlon(k) between the two RTK mobile stations at the k-th sampling moment. Δlat(k) = lat1(k) - lat2(k), Δlon(k) = lon1(k) - lon2(k). Take the absolute value of the arctangent of the ratio of Δlat to Δlon minus 360° as the heading angle θ(k) of the AGV at the k-th sampling moment;

[0066] If lon1(k) < lon2(k) and lat1(k) ≥ lat2(k), then calculate the latitude difference Δlat(k) and longitude difference Δlon(k) between the two RTK mobile stations at the k-th sampling moment. Δlat(k) = lat1(k) - lat2(k), Δlon(k) = lon1(k) - lon2(k). Take the absolute value of the arctangent of the ratio of Δlat to Δlon minus 180° as the heading angle θ(k) of the AGV at the k-th sampling moment;

[0067] If lon1(k) < lon2(k) and lat1(k) < lat2(k), then calculate the latitude difference Δlat(k) and longitude difference Δlon(k) between the two RTK mobile stations at the k-th sampling moment. Δlat(k) = lat1(k) - lat2(k), Δlon(k) = lon1(k) - lon2(k). Take the value of the arctangent of the ratio of Δlat to Δlon plus 180° as the heading angle θ(k) of the AGV at the k-th sampling moment;

[0068] S43, if lon1(k) = lon2(k) and lat1(k) > lat2(k), then the heading angle θ(k) of the AGV at the k-th sampling moment is 90°;

[0069] If lon1(k) = lon2(k) and lat1(k) < lat2(k), then the heading angle θ(k) of the AGV at the k-th sampling moment is 270°.

[0070] S5, according to the position coordinates (x1(k), y1(k)) of the first mobile station and the position coordinates (x2(k), y2(k)) of the second mobile station in the local coordinate system at the k-th sampling moment, calculate the centroid coordinates (x(k), y(k)) of the automatic guided vehicle AGV at the k-th sampling moment.

[0071] The calculation method for the centroid coordinates (x(k), y(k)) of the automatic guided vehicle AGV at the k-th sampling moment is: x(k) = [x1(k) + x2(k)] / 2; y(k) = [y1(k) + y2(k)] / 2.

[0072] S6, based on the center of mass coordinates (x(k), y(k)) of the AGV at the kth sampling moment, calculate the position coordinates (X(k), Y(k)) of the automatic guided vehicle AGV in the local coordinate system at the kth sampling moment, and obtain the actual physical posture (X(k), Y(k), θ(k)) of the automatic guided vehicle AGV in the local coordinate system at the kth sampling moment.

[0073] The calculation method of the position coordinates (X(k), Y(k)) of the automatic guided vehicle AGV in the local coordinate system at the kth sampling time is:

[0074] X(k)=C lon x(k), Y(k) = C lat y(k);

[0075] Among them, C lon is the longitude physical distance conversion coefficient, C lat is the latitude physical distance conversion coefficient.

[0076] In this embodiment, the calibration method of the physical distance conversion coefficient is as follows:

[0077] Since the earth is an ellipsoid, it needs to be calibrated in both longitude and latitude. During the calibration process, the RTK mobile station needs to be kept more than 6 meters away from the base station.

[0078] For longitude physical distance conversion factor C lon Calibration: First, measure an x-axis distance segment with an actual physical distance of 1 meter along the east-west direction, that is, along the x-axis direction. Then place the RTK mobile station at both ends of the x-axis distance segment for positioning to obtain the longitude difference of the RTK mobile station at both ends of the distance segment. Finally, divide 1 meter by the longitude difference to get the ratio, which is C lon .

[0079] For latitude physical distance conversion factor C lat Calibration: First, measure a y-axis distance segment with an actual physical distance of 1 meter along the north-south direction, that is, along the y-axis direction. Then place the RTK mobile station at both ends of the y-axis distance segment for positioning to obtain the latitude difference of the RTK mobile station at both ends of the distance segment. Finally, divide 1 meter by the latitude difference to obtain the ratio, which is C lat .

[0080] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A positioning and navigation method based on a dual-carrier phase differential mobile station, characterized in that: The following steps are involved: S1, arrange two RTK mobile stations on the automatic guided vehicle AGV, namely the first mobile station and the second mobile station; S2, performing the k-th acquisition using satellite positioning, and obtaining the GPS positions of the first mobile station, the second mobile station, and the base station at the k-th sampling time, respectively, wherein the GPS positions include accuracy and latitude; Among them, the longitude of the first mobile station at the kth sampling time is lon1(k), and the latitude is lat1(k); the longitude of the second mobile station at the kth sampling time is lon2(k), and the latitude is lat2(k); the longitude of the base station at the kth sampling time is baselon(k), and the latitude is baselat(k); S3, establish a local coordinate system with the base station as the origin, and obtain the position coordinates (x1(k), y1(k)) of the first mobile station in the local coordinate system and the position coordinates (x2(k), y2(k)) of the second mobile station in the local coordinate system at the kth sampling time according to the GPS positions of the first mobile station, the second mobile station, and the base station at the kth sampling time; S4, according to the GPS positions of the first mobile station and the second mobile station at the kth sampling time, calculate the heading angle θ(k) of the automatic guided vehicle AGV at the kth sampling time, θ(k)∈[0°,360°]; S5, calculate the center of mass coordinates (x(k), y(k)) of the automatic guided vehicle AGV at the kth sampling moment according to the position coordinates (x1(k), y1(k)) of the first mobile station in the local coordinate system and the position coordinates (x2(k), y2(k)) of the second mobile station in the local coordinate system at the kth sampling moment; S6, based on the center of mass coordinates (x(k), y(k)) of the AGV at the kth sampling moment, calculate the position coordinates (X(k), Y(k)) of the automatic guided vehicle AGV in the local coordinate system at the kth sampling moment, and obtain the actual physical posture (X(k), Y(k), θ(k)) of the automatic guided vehicle AGV in the local coordinate system at the kth sampling moment.

2. A positioning and navigation method based on a dual-carrier phase differential mobile station according to claim 1, characterized in that: In step S1, the two RTK mobile stations are arranged on the front and rear sides of the automatic guided vehicle AGV respectively, and the centers of the two RTK mobile stations are on the same straight line.

3. A positioning and navigation method based on a dual-carrier phase differential mobile station according to claim 2, characterized in that: In step S4, the calculation method of the heading angle θ(k) of the automatic guided vehicle AGV at the kth sampling time is as follows: S41, determining whether the longitude lon1(k) of the first mobile station and the longitude lon2(k) of the second mobile station at the kth sampling time are equal, if not, proceeding to step S42, otherwise proceeding to step S43; S42, if lon1(k)>lon2(k), and lat1(k)≥lat2(k), then calculate the latitude difference Δlat(k) and longitude difference Δlon(k) of the two RTK mobile stations at the kth sampling time, Δlat(k)=lat1(k)-lat2(k), Δlon(k)=lon1(k)-lon2(k), and take the arc tangent value of the ratio of Δlat and Δlon as the heading angle θ(k) of the AGV at the kth sampling time; If lon1(k) > lon2(k) and lat1(k) < lat2(k), then calculate the latitude difference Δlat(k) and longitude difference Δlon(k) between the two RTK mobile stations at the k-th sampling moment. Δlat(k) = lat1(k) - lat2(k), Δlon(k) = lon1(k) - lon2(k). Take the absolute value of the arctangent of the ratio of Δlat to Δlon minus 360° as the heading angle θ(k) of the AGV at the k-th sampling moment; If lon1(k) < lon2(k) and lat1(k) ≥ lat2(k), then calculate the latitude difference Δlat(k) and longitude difference Δlon(k) between the two RTK mobile stations at the k-th sampling moment. Δlat(k) = lat1(k) - lat2(k), Δlon(k) = lon1(k) - lon2(k). Take the absolute value of the arctangent of the ratio of Δlat to Δlon minus 180° as the heading angle θ(k) of the AGV at the k-th sampling moment; If lon1(k) < lon2(k) and lat1(k) < lat2(k), then calculate the latitude difference Δlat(k) and longitude difference Δlon(k) between the two RTK mobile stations at the k-th sampling moment. Δlat(k) = lat1(k) - lat2(k), Δlon(k) = lon1(k) - lon2(k). Take the value of the arctangent of the ratio of Δlat to Δlon plus 180° as the heading angle θ(k) of the AGV at the k-th sampling moment; S43, if lon1(k) = lon2(k) and lat1(k) > lat2(k), then the heading angle θ(k) of the AGV at the k-th sampling moment is 90°; If lon1(k) = lon2(k) and lat1(k) < lat2(k), then the heading angle θ(k) of the AGV at the k-th sampling moment is 270°.

4. The positioning and navigation method based on dual-carrier phase differential mobile station according to claim 1, characterized in that: In step S3, according to the difference between the GPS positions of the first mobile station and the base station at the k-th sampling moment, obtain the position coordinates (x1(k), y1(k)) of the first mobile station in the local coordinate system at the k-th sampling moment; according to the difference between the GPS positions of the second mobile station and the base station at the k-th sampling moment, obtain the position coordinates (x2(k), y2(k)) of the second mobile station in the local coordinate system at the k-th sampling moment.

5. The positioning and navigation method based on dual-carrier phase differential mobile station according to claim 1, characterized in that: In step S5, the calculation method of the centroid coordinates (x(k), y(k)) of the automatic guided vehicle AGV at the k-th sampling moment is as follows: x(k) = [x1(k) + x2(k)] / 2; y(k) = [y1(k) + y2(k)] / 2.

6. A positioning and navigation method based on a dual-carrier phase differential mobile station according to claim 1, characterized in that: In step S6, the calculation method of the position coordinates (X(k), Y(k)) of the automatic guided vehicle AGV in the local coordinate system at the k-th sampling moment is as follows: X(k)=C lon ·x(k),Y(k)=C lat ·y(k); Among them, C lon is the longitude physical distance conversion coefficient, C lat is the latitude physical distance conversion coefficient.

7. A positioning and navigation method based on a dual-carrier phase differential mobile station according to claim 6, characterized in that: The calibration method of the physical distance conversion coefficient is as follows: During the calibration process, keep a certain distance or more between the RTK mobile station and the base station; For longitude physical distance conversion factor C lon Calibration: First, measure an x-axis distance segment with an actual physical distance of α meters along the x-axis direction, then place the RTK mobile station at both ends of the x-axis distance segment for positioning to obtain the longitude difference of the RTK mobile station at both ends of the distance segment, and finally divide α meters by the longitude difference to obtain the ratio, which is C lon ; For latitude physical distance conversion factor C lat To calibrate, first measure a y-axis distance segment with an actual physical distance of α meters along the y-axis direction, then place the RTK mobile station at both ends of the y-axis distance segment for positioning, so as to obtain the latitude difference of the RTK mobile station at both ends of the distance segment, and finally divide α meters by the latitude difference to obtain the ratio, which is C lat .

8. A positioning and navigation method based on a dual-carrier phase differential mobile station according to claim 7, characterized in that: During the calibration process, the RTK mobile station should maintain a distance of more than 5 meters from the base station.

9. The positioning and navigation method based on dual-carrier phase differential mobile station according to claim 1, characterized in that: The positioning and navigation method is applied to a global real-time positioning system consisting of two RTK mobile stations, n satellites and a base station.

10. A positioning and navigation method based on a dual-carrier phase differential mobile station according to claim 9, characterized in that: n≥8。

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