Method and apparatus for vehicle positioning and orientation using single antenna GNSS

Abstract

The application provides a method and device for vehicle positioning and orientation by using single antenna GNSS, which comprises a single antenna, a steering wheel sensor and a calculation and display unit, the single antenna is installed above the midpoint of the rear wheel axle of the vehicle and is used for acquiring Beidou and GPS information, the steering wheel sensor is used for acquiring the rotating angle of the steering wheel, and the calculation and display unit is used for executing the method for vehicle positioning and orientation by using single antenna GNSS technology and displaying the result, the application adopts the single antenna to realize vehicle orientation and posture, which not only reduces the cost, but also is simple and convenient to install and implement and does not affect the driving on the road, compared with the double antenna, is more in line with the road driving conditions, the steering wheel angle acquisition is not affected by the outside world and is relatively robust, and the refreshing speed is fast.

Description

Technical Field

[0001] This invention relates to the field of satellite positioning technology, and in particular to a method for positioning and orientation using single-antenna GNSS technology and steering wheel rotation angle. Background Technology

[0002] With the development of satellite navigation technology, vehicle positioning technology has also made significant progress. Currently, mainstream technologies like BeiDou and GPS positioning have reached meter-level accuracy, while RTK positioning technology, widely used in driver training and testing, has achieved centimeter-level accuracy. Compared to positioning, vehicle orientation and attitude determination have progressed more slowly, currently employing three main technologies.

[0003] One method is based on BeiDou GPS trajectory points; the heading angle is obtained by subtracting the vectors of two consecutive points. This technology is widely used in mobile phone navigation within BeiDou GPS modules. Its advantages lie in its simplicity of implementation, requiring no additional hardware and employing a simple algorithm. However, its disadvantages are also obvious: inaccuracy at low speeds and lack of consideration for vehicle gear information.

[0004] Another method is based on dual-antenna RTK positioning, using a mobile base station and a mobile measuring station to calculate the relative distance between the two antennas, thereby determining the vehicle's heading angle. Its advantages include high accuracy, theoretically within 1 degree for a one-meter baseline. Disadvantages include complexity and high cost, requiring an additional set of antennas and corresponding circuit boards, cumbersome installation affecting driving, and theoretically doubling the failure and error rates due to RTK lock-up.

[0005] The advantages of BeiDou / GPS + Inertial Navigation + Fusion are that the accuracy is higher than any single solution. The disadvantages are: precision inertial navigation is relatively expensive; vehicle vibration is not friendly to inertial navigation; zero drift and cumulative error are difficult to solve; installation and calibration are relatively troublesome; and the effect gradually declines after a period of use. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method and apparatus for positioning and orientation using single-antenna GNSS technology and steering wheel rotation angle.

[0007] To achieve the above objectives, the present invention provides a method for vehicle positioning and orientation using a single-antenna GNSS, characterized by comprising the following steps:

[0008] S1. A satellite positioning receiver is installed vertically above the midpoint of the rear wheel axle of the vehicle to calibrate the relationship between the steering wheel angle and the front wheel deflection angle of the vehicle, thereby determining the relationship between the steering wheel and the turning radius of the vehicle;

[0009] S2. Obtain the tangential direction of any point in the trajectory, i.e., the heading angle of the vehicle, by fitting the trajectory curve;

[0010] S3. The change in heading angle can be deduced from the vehicle's turning radius, thereby calculating the new heading angle;

[0011] S4. To make the heading angle more accurate, the change in heading angle over the last distance and the results of S2 and S3 are fused together;

[0012] S5. When a new coordinate is found, repeat S2, S3, and S4 to obtain the vehicle heading angle at the current position.

[0013] Furthermore, the calibration method in step S1 includes modeling the vehicle's driving trajectory: two perpendicular lines passing through the centers of the two front wheels intersect the extension line of the rear wheel axle at a point O. Let point C be the midpoint of the rear wheel axle. A satellite positioning receiver is installed vertically above point C. The planar coordinates of point C are (x, y). Let point A be the midpoint of the left front wheel, point B be the midpoint of the left rear wheel, d be the wheelbase, and axle be the wheelbase between the front and rear axles. Since triangle OAB is a right triangle, the left front wheel turning angle a is equal to angle b of AOB. ; ;

[0014] Turning radius at point C ;

[0015] If the turning radius is known, the left front wheel steering angle The turning radius can be derived from the steering angle, and vice versa. First, measure the turning radius at point C corresponding to the steering wheel angle, and then calculate the front wheel rotation angle corresponding to the current steering wheel angle. For example, when the steering wheel angle is w, the turning radius at point C is... Then the corresponding front wheel steering angle is ;

[0016] Let the relationship between the left front wheel steering angle and the steering wheel angle be: Then the relationship coefficient By calculating the value of k at regular intervals of steering wheel angle, the relationship between the left front wheel angle and the steering wheel angle can be obtained. The smaller the interval of steering wheel angle, the more accurate the relationship between the front wheel angle and the steering wheel angle. Finally, the relationship between the turning radius r and the steering wheel angle can be obtained. ;

[0017] Furthermore, the method for calculating the vehicle's heading angle in step S2 also includes:

[0018] During vehicle movement, the satellite positioning receiver acquires coordinates every time interval t, and the coordinates are fitted using a cubic term to obtain the fitting function. Taking the first derivative of the fitted function, we obtain the tangential slope k at any point on the curve. The heading angle is defined as the angle between the vehicle's orientation and the y-axis, ranging from 0 to 360 degrees. If the vehicle is traveling in the direction of increasing x and is in drive, or traveling in the direction of decreasing x and is in reverse, then the heading angle is... If the vehicle is traveling in the direction of increasing x and is in reverse gear, or traveling in the direction of decreasing x and is in drive gear, then the yaw angle is... .

[0019] Furthermore, the new heading angle calculation method in step S3 includes defining the heading angle as the angle between the vehicle's orientation and the y-axis, ranging from 0 to 360 degrees. The vehicle turns the steering wheel to the right at a constant steering wheel angle w, and the rear wheel midpoint C successively passes through coordinates D and F at unit time t1, following a circular trajectory with G as the center. The turning radius of the vehicle is... ;

[0020] Let the vehicle's heading angle at point D be yaw. Then the angle from point D to the center point G is... If you turn the steering wheel to the left, then Let the coordinates of the center point G be ( , ),So , The orientation from the center point G to point D is... ;

[0021] The orientation from the center point G to point F is ,if >0, If <0, angleGF needs to be increased by 180 degrees. <0, If angleGF is less than 0, then 180 degrees needs to be subtracted; therefore, the change in heading angle is... ;

[0022] New heading angle .

[0023] Furthermore, step S4, which involves calculating the change in heading angle for the final distance and fusing the results of S2 and S3 with the heading angle, includes using coordinates received by a satellite positioning receiver. The Using the latest coordinates, the trajectory is fitted to obtain the fitted curve. After differentiating, the tangential direction can be obtained. Vehicle heading angle at coordinates Calculate using steering wheel angles Click Change in heading angle of a point ,So

[0024] The heading angle of the point is Similarly, the steering wheel angles can be used to deduce the following: , , , This is the heading angle at the latest coordinates.

[0025] A device for vehicle positioning and orientation using single-antenna GNSS is characterized by comprising a single antenna, a steering wheel sensor, and a calculation and display unit. The single antenna is installed above the midpoint of the rear wheel axle of the vehicle and is used to acquire BeiDou and GPS information. The steering wheel sensor acquires the steering wheel rotation angle. The calculation and display unit is used to execute the method for vehicle positioning and orientation using single-antenna GNSS technology as described above and display the results.

[0026] The beneficial effects of this invention are: it provides a method and apparatus for vehicle positioning and orientation using a single-antenna GNSS, comprising the following steps: S1. A satellite positioning receiver is installed vertically above the midpoint of the rear wheel axle of the vehicle, and the relationship between the steering wheel angle and the front wheel deflection angle is calibrated to determine the relationship between the steering wheel and the vehicle's turning radius; S2. The tangential direction of any point in the trajectory is obtained through trajectory fitting curve, i.e., the vehicle's heading angle; S3. The change in heading angle can be deduced from the vehicle's turning radius, thereby calculating a new heading angle; S4. To make the heading angle more accurate, the results of S2 and S3 are fused: the steering wheel degrees of the two sampling points are used to further calculate the change in heading angle and the heading angle of the last distance; S5. When a new coordinate is located, S2, S3, and S4 are repeated to obtain the vehicle's heading angle at the current position; this invention uses a single antenna for vehicle orientation and attitude determination, which not only reduces costs but also makes installation and implementation simple and convenient without affecting on-road driving. Compared with dual antennas, it is more in line with road driving conditions; the steering wheel angle acquisition is not affected by external factors and is relatively robust; the refresh rate can be very fast. Attached Figure Description

[0027] For ease of explanation, the present invention will be described in detail below with reference to the preferred embodiments and accompanying drawings.

[0028] Figure 1 This is a flowchart of a method and apparatus for vehicle positioning and orientation using a single-antenna GNSS as described in this invention;

[0029] Figure 2 This is a schematic diagram of step S1, vehicle trajectory modeling, of the method and apparatus for vehicle positioning and orientation using a single-antenna GNSS as described in this invention.

[0030] Figure 3 This is a schematic diagram of step S3, vehicle trajectory modeling, in the method and apparatus for vehicle positioning and orientation using a single-antenna GNSS as described in this invention.

[0031] Figure 4 This is a schematic diagram of a device for vehicle positioning and orientation using a single-antenna GNSS as described in this invention;

[0032] Figure 5 This is a flowchart illustrating steps S4 of the method and apparatus for vehicle positioning and orientation using a single-antenna GNSS as described in this invention, which calculates the change in heading angle over the last distance and fuses the results of S2 and S3. Detailed Implementation

[0033] The method and apparatus for vehicle positioning and orientation using a single-antenna GNSS according to the present invention will be further described below with reference to the accompanying drawings:

[0034] Example 1: As Figure 4 As shown,

[0035] This embodiment presents a device for vehicle positioning and orientation using a single-antenna GNSS system. The device includes a single antenna, a steering wheel sensor, and a calculation and display unit. The single antenna is mounted above the midpoint of the rear wheel axle and is used to acquire BeiDou and GPS information. The invention uses RTK for high-precision position calculation. The steering wheel sensor acquires the steering wheel rotation angle. The calculation and display unit executes the vehicle positioning and orientation method described above using single-antenna GNSS technology and displays the results. After installation, the entire system has a simple appearance and, compared to dual-antenna systems, is more suitable for road driving conditions.

[0036] like Figure 1 As shown in the figure, this embodiment proposes a method and apparatus for vehicle positioning and orientation using a single-antenna GNSS, which includes the following steps:

[0037] S1. A satellite positioning receiver is installed vertically above the midpoint of the rear wheel axle of the vehicle to calibrate the relationship between the steering wheel angle and the front wheel deflection angle of the vehicle, thereby determining the relationship between the steering wheel and the turning radius of the vehicle;

[0038] S2. Obtain the tangential direction of any point in the trajectory, i.e., the heading angle of the vehicle, by fitting the trajectory curve;

[0039] S3. The change in heading angle can be deduced from the vehicle's turning radius, thereby calculating the new heading angle;

[0040] S4. To make the heading angle more accurate, the change in heading angle over the last distance and the results of S2 and S3 are fused together;

[0041] S5. When a new coordinate is found, repeat S2, S3, and S4 to obtain the vehicle heading angle at the current position.

[0042] like Figure 2As shown, the relationship between the steering wheel angle and the front wheel deflection angle is calibrated to determine the relationship between the steering wheel and the vehicle's turning radius. Most passenger car steering conforms to the Ackermann steering model: during vehicle operation (straight lines and turns), the movement of each wheel follows its natural trajectory, ensuring that the tires are always in ideal rolling contact with the ground. The characteristics of Ackermann steering are: When a vehicle is traveling in a straight line, the axles of all four wheels are parallel to each other and perpendicular to the longitudinal center plane of the vehicle. During a vehicle's turning motion, all wheels must roll in a circle around a momentary center point. For example... Figure 2 As shown, two perpendicular lines passing through the centers of the two front wheels intersect the extension of the rear axle at point O. This point is the center of the circle the vehicle turns. Point C is the midpoint of the rear axle. A satellite positioning receiver is installed vertically above point C, providing the current planar coordinates (x, y) of point C. d is the wheelbase, and axle is the wheelbase between the front and rear axles; both d and axle can be measured. Triangle OAB is a right triangle, so the turning angle 'a' of the left front wheel is equal to angle 'b'.

[0043] The calibration method in step S1 includes modeling the vehicle's driving trajectory: two perpendicular lines passing through the centers of the two front wheels intersect the extension line of the rear wheel axle at point O. Let point C be the midpoint of the rear wheel axle. A satellite positioning receiver is installed vertically above point C. The planar coordinates of point C are (x, y). Let point A be the midpoint of the left front wheel, point B be the midpoint of the left rear wheel, d be the wheelbase, and axle be the wheelbase between the front and rear axles. Since triangle OAB is a right triangle, the left front wheel turning angle a is equal to angle b of AOB. ; Turning radius at point C ;

[0044] If the turning radius is known, the left front wheel steering angle The turning radius can be derived from the steering angle, and vice versa. First, measure the turning radius at point C corresponding to the steering wheel angle, and then calculate the front wheel rotation angle corresponding to the current steering wheel angle. For example, when the steering wheel angle is w, the turning radius at point C is... Then the corresponding front wheel steering angle is ;

[0045] Let the relationship between the left front wheel steering angle and the steering wheel angle be: Then the relationship coefficient By calculating the value of k at regular intervals of steering wheel angle, the relationship between the left front wheel angle and the steering wheel angle can be obtained. The smaller the interval of steering wheel angle, the more accurate the relationship between the front wheel angle and the steering wheel angle. Finally, the relationship between the turning radius r and the steering wheel angle can be obtained. ;

[0046] The method for calculating the vehicle's heading angle in step S2 also includes:

[0047] The trajectory fitting curve can obtain the tangential direction at any point in the trajectory, which is the vehicle's heading angle. During the vehicle's movement, the satellite positioning receiver obtains the coordinates every time interval t. The coordinates are then fitted with a cubic term to obtain the fitting function. Taking the first derivative of the fitted function, we obtain the tangential slope k at any point on the curve. The heading angle is defined as the angle between the vehicle's orientation and the y-axis, ranging from 0 to 360 degrees. If the vehicle is traveling in the direction of increasing x and is in drive, or traveling in the direction of decreasing x and is in reverse, then the heading angle is...

[0048] If the vehicle is traveling in the direction of increasing x and is in reverse gear, or traveling in the direction of decreasing x and is in drive gear, then the yaw angle is... .

[0049] like Figure 3 As shown, the new heading angle calculation method in step S3 includes defining the heading angle as the angle between the vehicle's orientation and the y-axis, ranging from 0 to 360 degrees. The vehicle turns the steering wheel to the right and moves forward at a constant steering wheel angle w. The midpoint C of the rear wheel passes successively through coordinates D at unit time t and F at unit time t1, and the trajectory is an arc with point G as the center. Because a satellite positioning receiver is installed above point C, the coordinates of point D can be obtained. Coordinates of point F When a vehicle is moving in a circle, the tangential direction at point D is obviously the vehicle's heading at point D, and the tangential direction at point C is the vehicle's heading at point C. The angle f between the tangential directions is the change in the heading angle. From geometric relationships, we know that angle f is equal to angle g.

[0050] The calculation method for angle f is as follows:

[0051] DG distance, i.e., turning radius

[0052] Let the vehicle's heading angle at point D be yaw. Then the angle from point D to the center point G is... If you turn the steering wheel to the left, then Let the coordinates of the center point G be ( , ),So , The orientation from the center point G to point D is... ;

[0053] The orientation from the center point G to point F is ,if >0, If <0, angleGF needs to be increased by 180 degrees. <0, If angleGF is less than 0, then 180 degrees needs to be subtracted; therefore, the change in heading angle is... ;

[0054] New heading angle .

[0055] The change in heading angle at the current position can be obtained by adding the vehicle's turning radius to the tangential direction at a point on the trajectory fitting curve.

[0056] The new heading angle calculation method in step S3 above, such as Figure 3 As shown, the tangential direction at point D, i.e., the heading angle at point D, is calculated from the trajectory fitting curve. When the steering wheel angle remains constant, the heading angle at point F can be directly calculated through fitting. However, considering the disturbances during state changes, the heading angle at point F requires further processing. During state changes, the steering wheel angle generally changes, and these changes are also affected by factors such as ground adhesion, tire pressure, and wear, meaning the turning radius changes. Therefore, to ensure a more accurate heading angle, the results of steps S2 and S3 need to be fused.

[0057] Kalman filtering can be used here. For example, the state transition equation can be established using the third point, the observations can be established using the second point, and the final position and heading angle can be calculated using an iterative method.

[0058] When the new coordinates are located, repeat steps S2, S3, and S4 to obtain the vehicle heading angle at the current position.

[0059] Example 2:

[0060] like Figure 5 As shown, step S4 calculates the change in heading angle for the last distance and integrates the results of S2 and S3 using the heading angle:

[0061] The steering wheel angle changes at two sampling points are used to further calculate the change in heading angle for the final short distance. For example, if the satellite positioning receiver reports a coordinate (x, y) every time interval t, the coordinates at t0 are... At this moment, the steering wheel angle is w0, and the coordinates at time t1 after time t are... If the steering wheel angle is w1 at this point, then it can be approximated that the car is making circular motion with a steering wheel angle of (w0+w1) / 2 within this short period of time. Therefore, the heading angle at time t1 can be calculated. Similarly, after reporting the coordinates at time t2, the heading angle at time t2 can be further calculated from the heading angle obtained at time t1.

[0062] The trajectory fitting curve can fit the tangential direction of any point on the curve, but the tangential direction at the end is often not very accurate and deviates greatly from the true heading angle, so it cannot be used directly. Therefore, in this embodiment, a point that is a certain distance away from the latest point is used to obtain the tangential heading of that point. Then, this point is used as the starting point to calculate the subsequent heading angle change using the steering wheel, and the calculation continues until the heading angle change at the current position is reached, thereby determining the heading angle at the current position.

[0063] Coordinates received by a satellite positioning receiver , Using the latest coordinates, the trajectory is fitted to obtain the fitted curve. After differentiating, the tangential direction can be obtained. Vehicle heading angle at coordinates Then use the steering wheel to calculate Click Change in heading angle of a point ,So The heading angle of the point is Similarly, the steering wheel angles can be used to deduce the following: , , , This is the heading angle at the latest coordinates.

[0064] In embodiments one and two, other positioning technologies besides RTK, such as PPP, can also be used; in addition to the Ackerman steering model, the fusion algorithm in the embodiments can also use extended Kalman filtering.

[0065] The above description is only a preferred embodiment of the present invention and is 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 within the protection scope of the present invention.

Claims

1. A method for vehicle positioning and orientation using a single-antenna GNSS, characterized in that, Includes the following steps: S1. A satellite positioning receiver is installed vertically above the midpoint of the rear wheel axle of the vehicle to calibrate the relationship between the steering wheel angle and the front wheel deflection angle of the vehicle, thereby determining the relationship between the steering wheel and the turning radius of the vehicle; S2. Obtain the tangential direction of any point in the trajectory, i.e., the heading angle of the vehicle, by fitting the trajectory curve; S3. The change in heading angle can be deduced from the vehicle's turning radius, thereby calculating the new heading angle; S4. To make the heading angle more accurate, the change in heading angle over the last distance and the results of S2 and S3 are fused together. S5. When a new coordinate is found, repeat S2, S3, and S4 to obtain the vehicle heading angle at the current position.

2. The method for vehicle positioning and orientation using a single-antenna GNSS according to claim 1, characterized in that, The calibration method in step S1 includes modeling the vehicle's driving trajectory: two perpendicular lines passing through the centers of the two front wheels intersect the extension line of the rear wheel axle at point O. Let point C be the midpoint of the rear wheel axle. A satellite positioning receiver is installed vertically above point C. The planar coordinates of point C are (x, y). Let point A be the midpoint of the left front wheel, point B be the midpoint of the left rear wheel, d be the wheelbase, axle be the wheelbase between the front and rear axles, and triangle OAB be a right triangle. Therefore, the left front wheel turning angle a is equal to angle b of AOB. ； ; Turning radius at point C ; Left front wheel corner ; Let the relationship between the left front wheel steering angle and the steering wheel angle be: Then the relationship coefficient ; By calculating the value of k at regular intervals of steering wheel angle, the relationship between the left front wheel angle and the steering wheel angle can be obtained, and finally, the relationship between the turning radius r and the steering wheel angle can be obtained. .

3. The method for vehicle positioning and orientation using a single-antenna GNSS according to claim 2, characterized in that, The step S2 of calculating the vehicle's heading angle also includes: During vehicle movement, the satellite positioning receiver acquires coordinates every time interval t, and the coordinates are fitted using a cubic term to obtain the fitting function. By taking the first derivative of the fitted function, we can obtain the tangential slope k at any point on the curve. The heading angle is defined as the angle between the vehicle's orientation and the y-axis, ranging from 0 to 360 degrees. If the vehicle is traveling in the direction of increasing x and is in drive, or traveling in the direction of decreasing x and is in reverse, then the heading angle is... If the vehicle is traveling in the direction of increasing x and is in reverse gear, or traveling in the direction of decreasing x and is in drive gear, then the yaw angle is... .

4. The method for vehicle positioning and orientation using a single-antenna GNSS according to claim 3, characterized in that, The new heading angle calculation method in step S3 includes defining the heading angle as the angle between the vehicle's orientation and the y-axis, ranging from 0 to 360 degrees. The vehicle moves forward at a constant steering wheel angle w when the steering wheel is turned to the right. The midpoint C of the rear wheel passes successively through coordinates D and F at unit time t1, following a circular trajectory with point G as the center. The turning radius of the vehicle is... ; Let the heading angle of the vehicle at point D be yaw, then the angle from D to G is... If you turn the steering wheel to the left, then ; Let the coordinates of point G be ( , ),So , ; The orientation from the center point G to point D is ; The orientation from the center point G to point F is ,if >0, If <0, angleGF needs to be increased by 180 degrees. <0, If angleGF is less than 0, then 180 degrees need to be subtracted. Change in heading angle ; New heading angle .

5. A method for vehicle positioning and orientation using a single-antenna GNSS according to claim 4, characterized in that, Step S4, which involves calculating the change in heading angle for the final distance and fusing the results of S2 and S3 with the heading angle, includes using coordinates received by a satellite positioning receiver. The Using the latest coordinates, the trajectory is fitted to obtain the fitted curve. After differentiating, the tangential direction can be obtained. Vehicle heading angle at coordinates Calculate using steering wheel angles Click Change in heading angle of a point ,So The heading angle of the point is Similarly, the steering wheel angles can be used to deduce the following: , , , This is the heading angle at the latest coordinates.

6. A device for vehicle positioning and orientation using a single-antenna GNSS, characterized in that, The system includes a single antenna, a steering wheel sensor, and a computing and display unit. The single antenna is installed above the midpoint of the rear wheel axle of the vehicle and is used to acquire BeiDou and GPS information. The steering wheel sensor acquires the steering wheel rotation angle. The computing and display unit is used to execute the vehicle positioning and orientation method using single-antenna GNSS technology as described in any one of claims 1 to 5 and display the results.

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