A method for calculating slope based on repeated route elevation alignment

Abstract

The present invention discloses a slope calculation method based on repeated route altitude alignment, which regards each track data as a three-dimensional space curve of time, longitude and latitude, calculates the distance from each point to all points on other tracks, marks the serial numbers of the points closest to each other as a group, and finds the serial number correspondence of all points on the two tracks in order of time recursion, only goes forward but not backward, and corresponds the altitude of all tracks to the same data table, performs arithmetic averaging on the altitude of each point where the track coordinates are aligned, obtains a curve associated with the cumulative mileage and altitude, reduces noise, fits, removes burrs, and uses gradient to obtain the slope. The present invention performs alignment and superposition averaging of multiple routes based on the GPS information collected by the current vehicle-mounted Tbox device, thereby eliminating the excessive error caused by low precision.

Description

Technical Field

[0001] The invention belongs to the field of automobile dynamics and economy simulation calculation, and in particular is a method for calculating the slope of a repeated route based on altitude alignment. Background Art

[0002] As emission regulations become increasingly stringent, commercial vehicle companies are increasingly demanding fuel economy. Simulation, as an important means of economic verification during product development, can quickly simulate system results. The slope has a great impact on engine output power, but current simulation calculations have high requirements for slope accuracy. In order to truly reflect the kinematic process of the vehicle during driving, an accurate slope calculation method is an indispensable part.

[0003] The existing solution is to directly calculate the slope through a single data collection, but the error is too poor; or to use high-precision equipment such as gyroscopes, but the cost is too high; the accuracy of the collected altitude data is too low, and the accuracy of the slope calculated based on the altitude and vehicle speed is too low. If accurate slope collection is required, it is necessary to install gyroscopes and other expensive equipment. The currently collected time series data is generally 1hz, with the same frequency. Due to the different road widths and vehicle speeds at the same location, it is impossible to directly align and calculate according to the absolute values ​​of longitude and latitude. Summary of the invention

[0004] In view of the problems existing in the background technology, the purpose of the present invention is to provide a method for calculating the slope based on the repeated route altitude alignment with high accuracy, which can eliminate the errors caused by low accuracy.

[0005] To achieve the above object, the present invention provides a method for calculating the slope of a repeated route based on altitude alignment, comprising:

[0006] S1, extract multiple routes with the same trajectory;

[0007] S2, establish a three-dimensional coordinate system with time, longitude and latitude as coordinate axes, and draw the trajectory extracted in S1;

[0008] S3, select any trajectory as the reference trajectory and calculate the distance from each point on the reference trajectory to all points on other trajectories;

[0009] S4, mark the serial numbers of the points closest to each other as a group, and find the serial number correspondence of all points on each trajectory in turn according to the time recursive order;

[0010] S5, correspond the altitudes of all trajectories to the same data table according to the sequence number;

[0011] S6, performing arithmetic averaging on the altitudes of the points aligned with the trajectory coordinates to obtain a corrected time-altitude curve;

[0012] S7, calculating the distance from each point to the starting point according to the vehicle speed to obtain the cumulative mileage;

[0013] S8, establishing a mileage-altitude curve with the accumulated mileage and altitude as coordinate axes;

[0014] S9, curve fitting of the mileage-altitude curve;

[0015] S10, using a gradient method to obtain the slope of a designated track point on the mileage-altitude curve.

[0016] Preferably, in step S1, no less than 10 trajectory data identical to the target route are searched from the Internet of Vehicles platform.

[0017] Further preferably, the trajectory data includes longitude, latitude, altitude, and vehicle speed, the data is uninterrupted, and the sampling frequency of each trajectory is the same

[0018] Further preferably, the trajectory data is sorted by time, and if there is continuous data loss of less than 5s, it is supplemented by interpolation, and if the continuous data loss exceeds 5s, it needs to be calculated in segments.

[0019] Further preferably, for the data row whose longitude, latitude and altitude are all 0, it is determined that the GPS signal is lost, and an interpolation method can be used to complete it; before performing data alignment, delete the point where the vehicle speed is 0.

[0020] Preferably, in step S5, when the absolute ground distance between the corresponding two points exceeds 40 m, the altitude mark is a null value.

[0021] Preferably, high-order filtering is used to eliminate low-order noise on the mileage-altitude curve in step S8.

[0022] Preferably, in step S9, a spline fitting method is used to fit the mileage-altitude curve.

[0023] Preferably, in step S10, the slope is calculated after local moving smoothing processing is performed on the places where the slope exceeds 10% or the continuous slope change exceeds 0.4%.

[0024] As a preferred solution, it also includes S11, matching the calculated slope data to each track in sequence to obtain slope time series data matching the vehicle speed.

[0025] The beneficial effect of the present invention is that the present invention performs alignment and superposition averaging of multiple routes based on the GPS information collected by the current vehicle-mounted Tbox device, thereby eliminating excessive errors caused by low precision.

[0026] The present invention regards each trajectory data as a three-dimensional spatial curve of time, longitude and latitude, calculates the distance from each point to all points on other trajectories, marks the serial numbers of the points closest to each other as a group, and finds the serial number correspondence of all points on the two trajectories in turn according to the time recursive order, only going forward but not backward, corresponds the altitude of all trajectories to the same data table, takes the arithmetic average of the altitudes of each point whose trajectory coordinates are aligned, obtains a curve correlating the cumulative mileage with the altitude, performs noise reduction, fitting, and burr removal, and uses gradient to obtain the slope. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a flow chart of the present invention;

[0028] Figure 2 It is a schematic diagram of calculating the distance between two points of the present invention;

[0029] Figure 3 It is a schematic diagram of the corresponding relationship of the trajectory points of the present invention. DETAILED DESCRIPTION

[0030] The technical solution of the present invention (including the preferred technical solution) is further described in detail below by means of the accompanying drawings and by listing some optional 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.

[0031] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0032] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0033] The invention designs a slope calculation method based on repeated route altitude alignment, which adopts the nearest consistent algorithm, aligns the coordinates based on time domain data, calculates the arithmetic mean of the altitudes of the corresponding coordinate points, and obtains the slope by derivation of the mileage-altitude curve for the specified position.

[0034] The following combination Figures 1 to 3 Further details are given.

[0035] 1) Data preparation:

[0036] Search for no less than 10 trajectory data identical to the target route from the Internet of Vehicles platform. The data includes longitude, latitude, altitude, and vehicle speed. The data is uninterrupted and the sampling frequency of each trajectory is the same.

[0037] 2) Data processing:

[0038] The data is sorted by time. If the data is lost continuously for less than 5 seconds, it is supplemented by interpolation. If the data is lost continuously for more than 5 seconds, it needs to be calculated in segments. For data rows with longitude, latitude and altitude of 0, it is judged that the GPS signal is lost and can be supplemented by interpolation. Before aligning the data, delete the points with a speed of 0.

[0039] 3) Alignment of longitude and latitude coordinates:

[0040] Each trajectory data is regarded as a three-dimensional spatial curve of time, longitude and latitude. When recording altitude, the accuracy is generally 1m. Figure 2 The number in a square is the distance between the corresponding points of the two trajectories according to time. Trajectory 1 and trajectory 2 are optimized based on time for the shortest trajectory point distance. The first "1" in the lower left corner represents the distance between the first points on the two trajectories, and the "2" above the above "1" represents the distance between the second point on trajectory 2 and the first point on trajectory 1, and so on.

[0041] Randomly select a data as the reference track, calculate the distance from each point on the reference track to all points on other tracks, mark the points closest to each other as a group, and follow the time recursion order, only go forward and never go back, find the two closest points corresponding to the two tracks, and find the corresponding relationship of the serial numbers of all points on the two tracks in turn, that is, the distance between all two points is the shortest. According to the serial number, the altitude of the two tracks is mapped to the same data table. If the absolute ground distance between the two corresponding points exceeds 40m, the altitude is marked as a null value. Similarly, the altitude of all tracks is mapped to the same data table. Figure 3 As shown, the two trajectories have similar waveforms, and the line between the trajectories is the two points with the shortest distance.

[0042] 4) Mileage-altitude curve:

[0043] The altitude of each point aligned with the trajectory coordinates is averaged, and the null value is not included in the average calculation to obtain the corrected time-altitude curve. Considering the altitude drift caused by GPS repositioning after the vehicle is restarted, the local moving average is used for smoothing. Similarly, the distance from each point to the starting point is calculated according to the vehicle speed, which is the cumulative mileage. The curve formed by the accumulated mileage as the horizontal coordinate and the altitude as the vertical coordinate uses high-order filtering to eliminate low-order noise.

[0044] 5) Road longitudinal section curve fitting:

[0045] The frequency of the collected data is 1 Hz, and the accumulated mileage-altitude is discrete data. In order to perform derivative calculations, curve fitting is required to retain the original information as much as possible, and the spline fitting method is used.

[0046] 6) Gradient extraction and deburring:

[0047] For the slope of the specified trajectory point, the cumulative mileage-altitude gradient method is used, and dx is taken as 20. Because the road section has a curvature radius limit and there is a certain difference from the curve, resulting in a local excessive slope, the local moving smoothing processing is performed for the slope exceeding 10% or the continuous slope change exceeding 0.4%.

[0048] 7) Slope matching

[0049] Repeat step 3) to match the calculated slope data to each track data in turn to obtain the slope time series data matching the vehicle speed.

[0050] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0052] Those skilled in the art will readily appreciate that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, combinations, replacements, improvements, etc. made within the spirit and principles of the present invention are included within the protection scope of the present invention.

Claims

1. A method for calculating the slope of a repeated route based on altitude alignment, characterized in that: The following steps are involved: S1, extract multiple routes with the same trajectory; S2, establish a three-dimensional coordinate system with time, longitude and latitude as coordinate axes, and draw the trajectory extracted in S1; S3, select any trajectory as the reference trajectory and calculate the distance from each point on the reference trajectory to all points on other trajectories; S4, mark the serial numbers of the points closest to each other as a group, and find the serial number correspondence of all points on each trajectory in turn according to the time recursive order; S5, correspond the altitudes of all trajectories to the same data table according to the sequence number; S6, performing arithmetic averaging on the altitudes of the points aligned with the trajectory coordinates to obtain a corrected time-altitude curve; S7, calculating the distance from each point to the starting point according to the vehicle speed to obtain the cumulative mileage; S8, establishing a mileage-altitude curve with the accumulated mileage and altitude as coordinate axes; S9, curve fitting of the mileage-altitude curve; S10, using a gradient method to obtain the slope of a designated track point on the mileage-altitude curve.

2. The method for calculating the slope based on the repeated route altitude alignment according to claim 1, characterized in that: In step S1, at least 10 trajectory data identical to the target route are searched from the Internet of Vehicles platform.

3. The method for calculating the slope based on the repeated route altitude alignment according to claim 2, characterized in that: The trajectory data includes longitude, latitude, altitude, and vehicle speed. The data is uninterrupted and the sampling frequency of each trajectory is the same.

4. The method for calculating the slope based on the repeated route altitude alignment according to claim 3, characterized in that: The trajectory data are sorted by time. If the continuous data loss is less than 5s, it is supplemented by interpolation. If the continuous data loss exceeds 5s, it needs to be calculated in segments.

5. The method for calculating the slope based on the repeated route altitude alignment according to claim 4, characterized in that: For data rows where longitude, latitude, and altitude are all 0, it is determined that the GPS signal is lost and can be supplemented by interpolation. Before data alignment, delete the points where the vehicle speed is 0.

6. The method for calculating the slope based on the repeated route altitude alignment according to claim 1, characterized in that: In step S5, when the absolute ground distance between the two corresponding points exceeds 40 m, the altitude mark is a null value.

7. The method for calculating the slope based on the repeated route altitude alignment according to claim 1, characterized in that: A high-order filtering process is used on the mileage-altitude curve in step S8 to eliminate low-order noise.

8. The method for calculating the slope based on the repeated route elevation alignment according to claim 1, characterized in that: In step S9, a spline fitting method is used to fit the mileage-altitude curve.

9. The method for calculating the slope based on the repeated route altitude alignment according to claim 1, characterized in that: In step S10, the slope is calculated after the local moving smoothing process is performed on the places where the slope exceeds 10% or the continuous slope change exceeds 0.4%.

10. The method for calculating the slope based on the repeated route altitude alignment according to any one of claims 1 to 9, characterized in that: The method further includes S11, matching the calculated slope data to each track in sequence to obtain slope time series data matching the vehicle speed.

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