Railway vehicle positioning method based on GPS, odometer and gyroscope signals

Abstract

The present invention belongs to the technical field of rail vehicle positioning, and proposes a rail vehicle positioning method based on GPS, odometer and gyroscope signals: the speed and displacement of the vehicle are calculated according to the wheel axle speed signal; the GPS speed and the vehicle speed measured by the speed sensor are compared within a period of time, and the GPS coordinates are judged to be accurate according to the comparison result. If it is inaccurate, the updated coordinates are constructed using the vehicle displacement measured by the speed sensor and the difference of the GPS coordinates before and after the period of time, and the updated coordinates are replaced by the GPS coordinates, and the running track of the vehicle in the digital map is determined; the turning radius of the vehicle body at different times is calculated according to the rotation rate of the vehicle body around the horizontal plane and the vehicle speed; the curve radius corresponding to different positions in the digital map is used, and the mileage difference between the turning radius of the vehicle body and the curve radius is compared according to the size and direction of the curve at different times, and the real-time position of the vehicle operation is corrected. The present invention can accurately locate rail vehicles.

Description

Technical Field

[0001] The invention relates to the technical field of rail vehicle positioning, and in particular to a rail vehicle positioning method based on GPS, odometer and gyroscope signals. Background Art

[0002] At present, the positioning of vehicles in normal operation mainly relies on the GPS and odometer signals on the vehicle, while the positioning of vehicles parked in the station mainly relies on ground transponders. Among these three positioning signals, ground transponders are the most accurate and precise method. Due to high cost and difficulty in power supply, it is not advisable to install a large number of ground transponders on the railway main line. The positioning accuracy of commonly used GPS signals is limited and is easily affected by vehicle operating environments such as tunnels and bridges. Odometer signals are generally measured by measuring the rotation speed of the wheel axle, and then multiplied by the circumference of the wheel and the total running time. Among them, the theoretical contact circle radius of the wheel is equal to the design radius, but in the actual operation process, due to wear and damage, the actual radius of the wheel is usually smaller than the theoretical radius. Affected by the change of the wheel contact radius, relying solely on the odometer signal for positioning will also bring certain errors, and the error will continue to accumulate over time and cannot be corrected and eliminated. Therefore, the traditional vehicle operation positioning method relying on a single signal can no longer meet the requirements of vehicle and track status detection. Summary of the invention

[0003] The purpose of the present invention is to provide a railway vehicle positioning method based on GPS, odometer and gyroscope signals, which can comprehensively consider the relevant signals of GPS, gyroscope device and speed sensor, combine with digital map, and accurately locate the railway vehicle running on the main line, thereby improving the positioning accuracy of the railway vehicle.

[0004] The present invention solves the technical problem and adopts the following technical solution:

[0005] The method for positioning a railway vehicle based on GPS, odometer and gyroscope signals comprises the following steps:

[0006] Install GPS and gyroscope devices on the body of the railway vehicle, install a speed sensor on the wheel axle, and record the GPS coordinates and GPS speed of the vehicle at different times through GPS, record the rotation rate of the vehicle body around the horizontal plane through the gyroscope device, and record the wheel axle speed signal through the speed sensor;

[0007] Calculate the speed and displacement of the vehicle according to the wheel axle speed signal;

[0008] Compare the GPS speed measured by the GPS and the vehicle speed measured by the speed sensor within a period of time. If the deviation of the comparison result does not exceed the preset value, the GPS coordinates are judged to be accurate, otherwise the GPS coordinates are judged to be inaccurate;

[0009] When the GPS coordinates are inaccurate, during the period of time, the vehicle displacement measured by the rotation speed sensor and the difference between the GPS coordinates before and after the period of time are used to construct updated coordinates, and the updated coordinates replace the GPS coordinates, and determine the running track of the vehicle in the digital map;

[0010] Calculate the turning radius of the vehicle body at different times according to the rotation rate of the vehicle body around the horizontal plane and the vehicle speed;

[0011] By using the curve radius corresponding to different positions in the digital map and comparing the mileage difference between the vehicle turning radius and the curve radius according to the size and direction of the curve at different times, the real-time position of the vehicle can be corrected.

[0012] As a further optimization, when recording the wheel axle speed signal by the speed sensor, it also includes:

[0013] Get the minimum time interval required for the wheel to rotate one circle.

[0014] As a further optimization, after recording the time required for the wheel to rotate one circle, the method further includes:

[0015] The pulse signal threshold is set, and the minimum time interval required for the wheel to rotate one circle and the set pulse signal threshold are used to remove the interference peak signal, and the effective pulse peak signal is determined. The effective pulse peak signal is the time node in the axle speed signal when the wheel rotates one circle.

[0016] As a further optimization, when comparing the GPS speed measured by the GPS and the vehicle speed measured by the speed sensor over a period of time, the vehicle speed measured by the speed sensor is used as a reference;

[0017] The preset value is 8%~12%.

[0018] As a further optimization, the curve radius corresponding to different positions in the digital map is used to compare the mileage difference between the turning radius of the vehicle and the curve radius according to the size and direction of the curve at different times, and correct the real-time position of the vehicle, including:

[0019] The turning radius of the vehicle is expressed as , the curve radius is expressed as , the mileage error is expressed as Δ L ;

[0020] Assume that the vehicle moves from a certain position to the turning radius of the vehicle body within time T. , the corresponding theoretical mileage is , the radius of the curve in the digitized map The corresponding actual mileage is , then the mileage error , if Δ L>0, indicating that the calculated position of the vehicle in this section is ahead of its actual position. A linear correction method is used to subtract Δ from the mileage corresponding to each time step. L / T, updates the vehicle's position at all time steps in this interval.

[0021] The beneficial effects of the present invention are as follows: through the above-mentioned railway vehicle positioning method based on GPS, odometer and gyroscope signals, first, GPS and gyroscope devices are installed on the body of the railway vehicle, and a speed sensor is installed on the wheel axle, and the GPS coordinates and GPS speed of the vehicle running at different times are recorded by GPS, the rotation rate of the vehicle body around the horizontal plane is recorded by the gyroscope device, and the wheel axle speed signal is recorded by the speed sensor; secondly, the speed and displacement of the vehicle running are calculated according to the wheel axle speed signal; then, the GPS speed measured by GPS and the vehicle speed measured by the speed sensor within a period of time are compared, and if the deviation of the comparison result does not exceed the preset value, then The GPS coordinates are determined to be accurate, otherwise the GPS coordinates are determined to be inaccurate; when the GPS coordinates are inaccurate, within the period of time, the vehicle displacement measured by the rotation speed sensor and the difference between the GPS coordinates before and after the period of time are used to construct updated coordinates, and the updated coordinates replace the GPS coordinates, and the running track of the vehicle in the digitized map is determined; then, the turning radius of the vehicle body at different times is calculated according to the rotation rate of the vehicle body around the horizontal plane and the vehicle speed; finally, the curve radius corresponding to different positions in the digitized map is used, and the mileage difference between the turning radius of the vehicle body and the curve radius is compared according to the size and direction of the curve at different times, so as to correct the real-time position of the vehicle.

[0022] Therefore, the present invention abandons the traditional single railway vehicle positioning method, and comprehensively considers the relevant signals of GPS, gyroscope device and speed sensor, combined with digital map, to accurately locate the railway vehicle running on the main line, thereby improving the railway vehicle positioning accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a flow chart of a railway vehicle positioning method based on GPS, odometer and gyroscope signals in Embodiment 1 of the present invention;

[0024] Figure 2 The processing method of the wheel axle speed signal in the second embodiment of the present invention is applied, wherein Figure 2 (a) is a schematic diagram of the speed signal sample. Figure 2 (b) is a schematic diagram of the speed signal and its peak signal during the entire stroke. Figure 2 (c) is a schematic diagram of the speed signal after removing the interference peak;

[0025] Figure 3 The deviation of the speed signal measured by the GPS and the speed signal measured by the rotation speed sensor in the second embodiment of the present invention is applied;

[0026] Figure 4 A schematic diagram of two speed curves in a known digitized map in Example 2 of the present invention;

[0027] Figure 5 For Figure 4 Schematic diagram of the results of correcting the vehicle position for the two curves. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations. Example 1

[0029] This embodiment provides a railway vehicle positioning method based on GPS, odometer and gyroscope signals, and its flow chart is shown in Figure 1 , wherein the method comprises the following steps:

[0030] S1. Installing GPS and gyroscope devices on the body of a railway vehicle, installing a speed sensor on the wheel axle, and recording the GPS coordinates and GPS speed of the vehicle at different times through GPS, recording the rotation rate of the vehicle body around a horizontal plane through the gyroscope device, and recording the wheel axle speed signal through the speed sensor;

[0031] S2, calculating the speed and displacement of the vehicle according to the wheel axle speed signal;

[0032] S3, comparing the GPS speed measured by the GPS and the vehicle speed measured by the speed sensor within a period of time, if the deviation of the comparison result does not exceed a preset value, the GPS coordinates are judged to be accurate, otherwise the GPS coordinates are judged to be inaccurate;

[0033] S4. When the GPS coordinates are inaccurate, during the period of time, the vehicle displacement measured by the speed sensor and the difference between the GPS coordinates before and after the period of time are used to construct updated coordinates, and the updated coordinates are used to replace the GPS coordinates, and the running track of the vehicle in the digital map is determined;

[0034] S5, calculating the turning radius of the vehicle body at different times according to the rotation rate of the vehicle body around the horizontal plane and the vehicle speed;

[0035] S6. Using the curve radius corresponding to different positions in the digital map, according to the size and direction of the curve at different times, compare the mileage difference between the vehicle turning radius and the curve radius, and correct the real-time position of the vehicle.

[0036] In this embodiment, in order to calculate the speed and displacement of the vehicle through the wheel axle speed signal, the recording of the wheel axle speed signal through the speed sensor also needs to include: obtaining the minimum time interval required for the wheel to rotate one circle.

[0037] In order to remove the interference signal, in this embodiment, after recording the time required for the wheel to rotate one circle, the following steps are also required:

[0038] The pulse signal threshold is set, and the minimum time interval required for the wheel to rotate one circle and the set pulse signal threshold are used to remove the interference peak signal, and the effective pulse peak signal is determined. The effective pulse peak signal is the time node in the axle speed signal when the wheel rotates one circle.

[0039] It should be noted that when comparing the GPS speed measured by the GPS and the vehicle speed measured by the speed sensor over a period of time, the vehicle speed measured by the speed sensor is used as a reference; the preset value is 8%~12%. The preset value can be freely adjusted according to the actual working conditions, but its general range should be within 8%~12%.

[0040] Specifically, when correcting the real-time position of the vehicle, it is necessary to perform correction based on the mileage difference between the vehicle turning radius and the curve radius. Therefore, in this embodiment, using the curve radius corresponding to different positions in the digital map, comparing the mileage difference between the vehicle turning radius and the curve radius according to the size and direction of the curve at different times, and correcting the real-time position of the vehicle may include:

[0041] The turning radius of the vehicle is expressed as , the curve radius is expressed as , the mileage error is expressed as Δ L ;

[0042] Assume that the vehicle moves from a certain position to the turning radius of the vehicle body within time T. , the corresponding theoretical mileage is , the radius of the curve in the digitized map The corresponding actual mileage is , then the mileage error , if Δ L >0, indicating that the calculated position of the vehicle in this section is ahead of its actual position. A linear correction method is used to subtract Δ from the mileage corresponding to each time step. L / T, updates the vehicle's position at all time steps in this interval. Example 2

[0043] Based on Example 1, this example can be implemented through the following specific steps:

[0044] Step 1: Install GPS and gyroscope devices at appropriate locations (in the middle or at both ends) on the railway vehicle body, install a speed sensor on the axle as a data acquisition device for the odometer, and record the GPS coordinates of the vehicle at different times ( , ) and GPS speed , the vehicle body rotation rate φ around the horizontal plane and the wheel axle speed signal (One pulse signal is received for each rotation).

[0045] Step 2: Figure 2 (a) shows the wheel axle speed signal Record the time it takes for the wheel to make one revolution , the wheel will receive a pulse signal with a peak value of about 10 for each rotation, and the time domain bandwidth of the sensor pulse signal is about 0.02 seconds. First, we must determine and , that is, determine the local maximum peak. However, since the pulse signal has a width, it will receive redundant interference peaks. The minimum time interval required for the wheel to rotate one circle can be used to remove the redundant interference peaks.

[0046]

[0047] The wheel radius is R , V max and V min They represent the maximum speed and minimum speed of the vehicle during operation.

[0048] Here, assuming that the radius of the wheel is 0.46 meters and the maximum speed of the vehicle is 90 kilometers per hour, it takes at least 0.116 seconds for the wheel to rotate once. Here, the time interval between effective pulse peaks is set to 0.10 seconds (0.02 seconds to 0.116 seconds, and as close to 0.116 seconds as possible), which can remove the interference peak #1 caused by the pulse signal width. Figure 2 As shown in (b), there is also an interference peak at the position where the signal tends to 0. At this time, the pulse signal threshold can be taken , remove the interference signal #2 at the zero position, and the final result is shown in 2(c), where the peak value and its corresponding time can be obtained. Next, calculate the speed of the vehicle and displacement :

[0049]

[0050] Step 3: Compare the speed signal measured by GPS and the speed signal measured by the speed sensor If within a certain period of time and Error If the error is less than 10%, the GPS signal can be judged to be basically accurate. Otherwise, the GPS signal error is relatively large during this period and the coordinate information is unreliable.

[0051]

[0052] like Figure 3 As shown, in this case and The maximum error is about 8.7%, which is less than the allowable error value. It can be considered that the GPS signal is basically accurate.

[0053] Step 4: If the GPS coordinates within a certain period of time ( , ) is not credible, the displacement measured by the speed sensor can be used , interpolate the GPS coordinates before and after this time period to construct the coordinates (X n , Y n ), replace the unreliable coordinates and determine the vehicle's running trajectory in the digital map.

[0054] Step 5: According to the rotation rate φ of the vehicle body around the horizontal plane and the vehicle running speed Calculate the turning radius of the vehicle at different times :

[0055]

[0056] Step 6: Figure 4 and Figure 5 As shown, using the known curve radius corresponding to different positions in the digital map , according to the size and direction of the curve at different times, compare and The difference ΔL , correct the real-time position of the vehicle. For example, if a vehicle moves from a certain position to a curve within time T The corresponding mileage is , digital map The corresponding actual mileage is , then the error ,like ΔL >0, indicating that the calculated position of the vehicle in this section is ahead of its actual position. A linear correction method is used to subtract the mileage corresponding to each time step. ΔL / T, updates the vehicle's position at all time steps in this interval.

[0057] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A railway vehicle positioning method based on GPS, odometer and gyroscope signals, characterized in that: The steps include: A GPS and gyroscope device is installed on the body of a railway vehicle, and a speed sensor is installed on the axle as a data acquisition device for the odometer, and the GPS coordinates and GPS speed of the vehicle at different times are recorded by GPS, the rotation rate of the vehicle body around the horizontal plane is recorded by the gyroscope device, and the axle speed signal is recorded by the speed sensor; Calculate the speed and displacement of the vehicle according to the wheel axle speed signal; Compare the GPS speed measured by the GPS and the vehicle speed measured by the speed sensor within a period of time. If the deviation of the comparison result does not exceed the preset value, the GPS coordinates are judged to be accurate, otherwise the GPS coordinates are judged to be inaccurate; When the GPS coordinates are inaccurate, during the period of time, the vehicle displacement measured by the rotation speed sensor and the GPS coordinates before and after the period of time are interpolated to construct updated coordinates, and the updated coordinates replace the GPS coordinates, and determine the running track of the vehicle in the digital map; Calculate the turning radius of the vehicle body at different times according to the rotation rate of the vehicle body around the horizontal plane and the vehicle speed; By using the curve radius corresponding to different positions in the digital map and comparing the mileage difference between the vehicle turning radius and the curve radius according to the size and direction of the curve at different times, the real-time position of the vehicle can be corrected.

2. The method for positioning a railway vehicle based on GPS, odometer and gyroscope signals according to claim 1, characterized in that: When the wheel axle speed signal is recorded by the speed sensor, it also includes: Get the minimum time interval required for the wheel to rotate one circle.

3. The method for positioning a railway vehicle based on GPS, odometer and gyroscope signals according to claim 2, characterized in that: After obtaining the minimum time interval required for the wheel to rotate once, the method further includes: The pulse signal threshold is set, and the minimum time interval required for the wheel to rotate one circle and the set pulse signal threshold are used to remove the interference peak signal, and the effective pulse peak signal is determined. The effective pulse peak signal is the time node in the axle speed signal when the wheel rotates one circle.

4. The method for positioning a railway vehicle based on GPS, odometer and gyroscope signals according to claim 1, characterized in that: When comparing the GPS speed measured by the GPS and the vehicle speed measured by the rotation speed sensor over a period of time, the vehicle speed measured by the rotation speed sensor is used as a reference; The preset value is 8%~12%.

5. The method for positioning a railway vehicle based on GPS, odometer and gyroscope signals according to claim 1, characterized in that: The method uses the curve radius corresponding to different positions in the digital map, compares the mileage difference between the turning radius of the vehicle and the curve radius according to the size and direction of the curve at different times, and corrects the real-time position of the vehicle, including: The turning radius of the vehicle is expressed as , the curve radius is expressed as , the mileage error is expressed as Δ L ; Assume that the vehicle moves from a certain position to a turning radius of The corresponding theoretical mileage is , the radius of the curve in the digitized map The corresponding actual mileage is , then the mileage error , if Δ L >0, indicating that the calculated position of the vehicle in the segment is ahead of its actual position. A linear correction method is used to subtract Δ from the mileage corresponding to each time step. L / T, updates the vehicle's position at all time steps within the interval.

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