Absolute positioning method and device for vehicle

Abstract

The present invention relates to an absolute positioning method for a vehicle, the method including: receiving global navigation satellite system (GNSS) data and deviation correction data; receiving wheel speed information and steering wheel angle information; and determining the absolute pose of the vehicle based on the global navigation satellite system (GNSS) data, the deviation correction data, the wheel speed information, and the steering wheel angle information. The present invention further relates to an absolute positioning device, a computer storage medium, a computer program product, and a vehicle.

Description

[0001] Description

[0002] Title

[0003] ABSOLUTE POSITIONING METHOD AND DEVICE FOR VEHICLE

[0004] TECHNICAL FIELD

[0005] The present invention relates to the field of vehicle positioning, and more particularly, to an absolute positioning method and apparatus for a vehicle, a computer storage medium, a computer program product, and a vehicle.

[0006] BACKGROUND

[0007] Autonomous driving mainly comprises four parts, i.e., environmental perception, positioning and navigation, decision-making and planning, and control and execution. The positioning issue is an essential part of autonomous driving, and in a broad sense, is intended to address the problem of “Where am I,” and in a narrow sense, aims to determine the absolute position of a current vehicle in the world or on a digital map, or a relative position of the current vehicle with respect to the surrounding environment (such as roads, other vehicles, and pedestrians). Positioning provides basic position information for autonomous driving, and positioning precision directly determines the safety and accuracy of autonomous driving.

[0008] GNSS positioning technology is currently relatively mature, having a positioning precision at meter-level (about 10 meters). As a high-precision positioning scheme, real time kinematic (RTK) can achieve a positioning precision of 1 cm to 2 cm. However, RTK technology relies on observation data of a reference base station, and the accuracy thereof may gradually decrease as the distance from the reference base station increases and there is a base station switching delay. That is, although RTK technology can achieve a high level of precision, RTK is typically limited by the distance between stations.

[0009] Precise Point Positioning (PPP) came into being, and uses a single dual-frequency global navigation satellite system (GNSS) receiver to perform single-point positioning based on carrier phase observations as well as satellite orbits and clock difference products provided by the International GNSS Service (IGS). However, in a specific operating condition, particularly the operating condition in which vehicles stop and go while changing lanes, the precision of absolute positioning performed using PPP is low, which does not meet actual needs.

[0010] SUMMARY

[0011] According to one aspect of the present invention, provided is an absolute positioning method for a vehicle, the method comprising: receiving global navigation satellite system (GNSS) data and deviation correction data; receiving wheel speed information and steering wheel angle information; and determining the absolute pose of the vehicle based on the global navigation satellite system (GNSS) data, the deviation correction data, the wheel speed information, and the steering wheel angle information.

[0012] In addition or alternatively to the above solution, in the method described above, determining the absolute pose of the vehicle based on the global navigation satellite system (GNSS) data, the deviation correction data, the wheel speed information, and the steering wheel angle information comprises: calculating the absolute pose by fusing the global navigation satellite system (GNSS) data, the deviation correction data, an inertial navigation signal from an inertial measurement unit, the wheel speed information, and the steering wheel angle information using the Kalman filtering algorithm.

[0013] In addition or alternatively to the above solution, in the method described above, calculating the absolute pose by Kalman filtering of the global navigation satellite system (GNSS) data, the deviation correction data, the inertial navigation signal from the inertial measurement unit, the wheel speed information, and the steering wheel angle information comprises: determining whether the wheel speed information is below a first threshold; adjusting, based on the determination, the weight of the steering wheel angle information in the Kalman filtering algorithm; and calculating the absolute pose using the Kalman filtering algorithm on the basis of the global navigation satellite system (GNSS) data, the deviation correction data, the inertial navigation signal from the inertial measurement unit, and the adjusted steering wheel angle information.

[0014] In addition or alternatively to the above solution, in the method described above, adjusting, based on the determination, the weight of the steering wheel angle information in the Kalman filtering algorithm comprises: multiplying the steering wheel angle information by a first weight coefficient when the wheel speed information is below the first threshold; and multiplying the steering wheel angle information by a second weight coefficient when the wheel speed information is greater than or equal to the first threshold, wherein the first weight coefficient is greater than the second weight coefficient.

[0015] According to another aspect of the present invention, provided is an absolute positioning device for a vehicle, the device comprising: a first receiving apparatus, configured to receive global navigation satellite system (GNSS) data and deviation correction data; a second receiving apparatus, configured to receive wheel speed information and steering wheel angle information; and a determining apparatus, configured to determine the absolute pose of the vehicle based on the global navigation satellite system (GNSS) data, the deviation correction data, the wheel speed information, and the steering wheel angle information.

[0016] In addition or alternatively to the above solution, in the device described above, the determining apparatus comprises: a calculating unit, configured to calculate the absolute pose by fusing the global navigation satellite system (GNSS) data, the deviation correction data, an inertial navigation signal from an inertial measurement unit, the wheel speed information, and the steering wheel angle information using the Kalman filtering algorithm.

[0017] In addition or alternatively to the above solution, in the device described above, the calculating unit is configured to: determine whether the wheel speed information is below a first threshold; adjust, based on the determination, the weight of the steering wheel angle information in the Kalman filtering algorithm; and calculate the absolute pose using the Kalman filtering algorithm on the basis of the global navigation satellite system (GNSS) data, the deviation correction data, the inertial navigation signal from the inertial measurement unit, and the adjusted steering wheel angle information.

[0018] In addition or alternatively to the above solution, in the device described above, the calculating unit is configured to: multiply the steering wheel angle information by a first weight coefficient when the wheel speed information is below the first threshold; and multiply the steering wheel angle information by a second weight coefficient when the wheel speed information is greater than or equal to the first threshold, wherein the first weight coefficient is greater than the second weight coefficient. According to yet another aspect of the present invention, provided is a computer storage medium, comprising an instruction, wherein the instruction, when run, executes the above method.

[0019] According to yet another aspect of the present invention, provided is a computer program product, comprising a computer program, wherein the computer program, when executed by a processor, implements the above method.

[0020] According to yet another aspect of the present invention, provided is a vehicle, comprising: a wheel speed sensor; a steering wheel angle sensor; an antenna, and the absolute positioning device as described above, wherein the absolute positioning device is configured to receive the wheel speed information from the wheel speed sensor, receive the steering wheel angle information from the steering wheel angle sensor, and receive the global navigation satellite system (GNSS) data and the deviation correction data by means of the antenna.

[0021] The absolute positioning scheme for a vehicle in the embodiment of the present invention receives not only global navigation satellite system (GNSS) data and deviation correction data, but also wheel speed information and steering wheel angle information, and determines the absolute pose of the vehicle based on the received information (which comprises the wheel speed information and the steering wheel angle information). The absolute positioning scheme optimizes the problems of poor precision and unreliable positioning of absolute positioning in low-speed operating conditions by incorporating the steering wheel angle information and the wheel speed information, thereby improving the robustness of the absolute positioning product and having good engineering achievability.

[0022] BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The foregoing and other objectives and advantages of the present invention will be made more complete and clear from the following detailed description provided with reference to the accompanying drawings, wherein the same or similar elements use the same reference numerals. FIG. 1 shows a schematic flowchart of an absolute positioning method for a vehicle according to an embodiment of the present invention;

[0024] FIG. 2 shows a schematic structural view of an absolute positioning device according to an embodiment of the present invention;

[0025] FIG. 3 shows an input-output block diagram of an absolute positioning product that is located inside of a vehicle according to an embodiment of the present invention; and

[0026] FIG. 4 shows an algorithm schematic view of an absolute positioning method according to an embodiment of the present invention.

[0027] DETAILED DESCRIPTION

[0028] In the following, an absolute positioning scheme for a vehicle according to various exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0029] FIG. 1 shows a schematic flowchart of an absolute positioning method 1000 for a vehicle according to an embodiment of the present invention. As shown in FIG. 1 , the absolute positioning method 1000 for a vehicle includes the following steps: in step S110, receiving global navigation satellite system (GNSS) data and deviation correction data; in step S120, receiving wheel speed information and steering wheel angle information; and in step S130, determining the absolute pose of the vehicle based on the global navigation satellite system (GNSS) data, the deviation correction data, the wheel speed information, and the steering wheel angle information.

[0030] The global satellite navigation satellite (GNSS) includes the Global Positioning System (GPS) of the U.S., the Beidou satellite navigation system of China, the Galileo system of Europe, etc., and is a commonly-used positioning means in autonomous driving. The GNSS mainly consists of three parts, i.e., a space satellite group, a ground control station, and a client. The GNSS performs positioning using the Time of Flight (TOF) principle. When one satellite is used, the position of an object may be located on a sphere. When two satellites are used, the position of an object may be located on the intersection of the two spheres - a circle. When three satellites are used, an object may be located at the two intersection points of the above-mentioned circle and spheres. In practice, it is easy to determine that one of the intersection points is in space, and thus from a theoretical perspective, at least three satellites may be used to locate the position of an object.

[0031] In the context of the present invention, global navigation satellite system (GNSS) data can help the vehicle to determine the absolute position thereof. Although such data is sufficiently accurate for current navigation systems, the precision thereof cannot meet the requirements of autonomous driving. Thus, in order to further improve the accuracy, deviation correction data may be further received on the basis of the GNSS, and the deviation correction data can correct an erroneous GNSS positioning signal.

[0032] In one or more embodiments, the “global navigation satellite system (GNSS) data” and the “deviation correction data” in step S110 may be received by means of an antenna (from the global navigation satellite system or a cloud).

[0033] In one or more embodiments, the “wheel speed information” and the “steering wheel angle information” in step S120 may be received from a wheel speed sensor and a steering wheel angle sensor, respectively.

[0034] In the context of the present invention, the “absolute pose” of the vehicle includes the absolute position and attitude (e.g., including the heading angle) of the vehicle. In one embodiment, step S130 includes: calculating the absolute pose by fusing the global navigation satellite system (GNSS) data, the deviation correction data, an inertial navigation signal (e.g., acceleration signal, angular velocity signal, etc.) from an inertial measurement unit, the wheel speed information, and the steering wheel angle information using the Kalman filtering algorithm.

[0035] In one embodiment, during the fusion process: first, whether the wheel speed information is below a first threshold is determined; second, the weight of the steering wheel angle information in the Kalman filtering algorithm is adjusted based on the determination; and finally, the absolute pose is calculated using the Kalman filtering algorithm on the basis of the global navigation satellite system (GNSS) data, the deviation correction data, the inertial navigation signal from the inertial measurement unit, and the adjusted steering wheel angle information.

[0036] In particular, adjusting, based on the determination, the weight of the steering wheel angle information in the Kalman filtering algorithm includes: multiplying the steering wheel angle information by a first weight coefficient when the wheel speed information is below the first threshold; and multiplying the steering wheel angle information by a second weight coefficient when the wheel speed information is greater than or equal to the first threshold, wherein the first weight coefficient is greater than the second weight coefficient. As such, the steering wheel angle information is incorporated into the Kalman filtering algorithm, whether the wheel speed information is below the first threshold is determined, and, in an operating condition in which the wheel speed information is below the first threshold, the specific weight of the steering wheel angle is increased in the fusion algorithm control policy of the GNSS, IMU, wheel speed, and steering wheel angle, resulting in a more precise positioning output (e.g., increased output precision of the heading angle).

[0037] Referring to FIG. 4, a schematic diagram of an absolute positioning algorithm according to an embodiment of the present invention is shown. As shown in FIG. 4, first, in step S410, wheel speed information is acquired; next, in step S420, whether the wheel speed is below a preset vehicle speed threshold is determined; if the wheel speed is below the preset vehicle speed threshold, then in step S430, the acquired steering wheel angle is multiplied by k and then by b, wherein k > 0 and b > 1 ; if the wheel speed is not below the preset vehicle speed threshold, then in step S440, the acquired steering wheel angle is multiplied by k, wherein k > 0. Here, both k and b are parameters which characterize the weight coefficients of the steering wheel angle in the Kalman filtering in different vehicle speed operating conditions, and the values of both parameters may vary depending on the actual situation. Finally, in step S450, global navigation satellite system (GNSS) data, deviation correction data, an inertial navigation signal (e.g., acceleration signal, angular velocity signal, etc.) from an inertial measurement unit (IMU), and the adjusted steering wheel angle are fused using the Kalman filtering algorithm, so as to output an absolute positioning. In one embodiment, the absolute positioning method 1000 optimizes performance in low- speed operating conditions by fusing steering wheel angle and wheel speed on the basis of PPP absolute positioning. The so called PPP absolute positioning, i.e., Precise Point Positioning, means that by using satellite orbits and clock difference products released by the IGS or the satellite orbits and clock difference parameters solved from IGS tracking station data, ionosphere-free pseudoranges and phase observations are used to eliminate the influence of correlation errors. Moreover, the rotation of the Earth, satellite and receiver phase center deviation, ocean loading, etc. are corrected using accurate models, and unmodeled errors such as zenith tropospheric delay error and multipath effect are solved as unknown parameters together with station coordinate parameters, so as to obtain high-precision three-dimensional coordinates of point positions under the ITRF frame (International Terrestrial Reference Frame).

[0038] Additionally, it will be readily appreciated by those skilled in the art that the absolute positioning method for a vehicle provided by one or more embodiments of the present invention may be implemented by a computer program. For example, the computer program is included in a computer program product, and when executed by a processor, the computer program implements the absolute positioning method 1000 for a vehicle according to one or more embodiments of the present invention. In another example, when a computer storage medium (e.g., a USB flash drive) that stores the computer program is connected to a computer, the absolute positioning method 1000 for a vehicle according to one or more embodiments of the present invention can be executed by running the computer program.

[0039] Referring to FIG. 2, FIG. 2 shows a schematic structural view of an absolute positioning device 2000 according to an embodiment of the present invention. As shown in FIG. 2, the absolute positioning device 2000 includes: a first receiving apparatus 210, a second receiving apparatus 220, and a determining apparatus 230. The first receiving apparatus 210 is configured to receive global navigation satellite system (GNSS) data and deviation correction data, the second receiving apparatus 220 is configured to receive wheel speed information and steering wheel angle information, and the determining apparatus 230 is configured to determine the absolute pose of a vehicle based on the global navigation satellite system (GNSS) data, the deviation correction data, the wheel speed information, and the steering wheel angle information. The global satellite navigation system (GNSS) includes the Global Positioning System (GPS) of the U.S., the Beidou satellite navigation system of China, the Galileo system of Europe, etc., and is a commonly-used positioning means in autonomous driving. The GNSS mainly consists of three parts, i.e., a space satellite group, a ground control station, and a client. The GNSS performs positioning with the Time of Flight (TOF) principle. When one satellite is used, the position of an object may be located on a sphere. When two satellites are used, the position of an object may be located on the intersection of the two spheres-a circle. When three satellites are used, an object may be located at the two intersection points of the above-mentioned circle and spheres. In practice, it is easy to determine that one of the intersection points is in space, and thus from a theoretical perspective, at least three satellites may be used to locate the position of an object.

[0040] In the context of the present invention, global navigation satellite system (GNSS) data can help the vehicle to determine the absolute position thereof. Although such data is sufficiently accurate for current navigation systems, the precision thereof cannot meet the requirements of autonomous driving. Thus, in order to further improve the accuracy, deviation correction data may be further received on the basis of the GNSS, and the deviation correction data can correct an erroneous GNSS positioning signal.

[0041] In one or more embodiments, the first receiving apparatus 210 may be configured to receive the “global navigation satellite system (GNSS) data” and the “deviation correction data” by means of an antenna (from the global navigation satellite system or a cloud).

[0042] In one or more embodiments, the second receiving apparatus 220 may be configured to receive the “wheel speed information” and the “steering wheel angle information” from a wheel speed sensor and a steering wheel angle sensor, respectively.

[0043] In the context of the present invention, the “absolute pose” of the vehicle includes the absolute position and attitude (e.g., including the heading angle) of the vehicle. In one embodiment, the determining apparatus 230 includes: a calculating unit, wherein the calculating unit is configured to calculate the absolute pose by fusing the global navigation satellite system (GNSS) data, the deviation correction data, an inertial navigation signal (e.g., acceleration signal, angular velocity signal, etc.) from an inertial measurement unit, the wheel speed information, and the steering wheel angle information using the Kalman filtering algorithm. In one embodiment, in the fusion process, the calculating unit is configured to: first, determine whether the wheel speed information is below a first threshold; second, adjust, based on the determination, the weight of the steering wheel angle information in the Kalman filter algorithm, and finally, calculate the absolute pose using the Kalman filtering algorithm on the basis of the global navigation satellite system (GNSS) data, the deviation correction data, the inertial navigation signal from the inertial measurement unit, and the adjusted steering wheel angle information.

[0044] In one embodiment, the calculating unit is configured to: multiply the steering wheel angle information by a first weight coefficient when the wheel speed information is below the first threshold; and multiply the steering wheel angle information by a second weight coefficient when the wheel speed information is greater than or equal to the first threshold, wherein the first weight coefficient is greater than the second weight coefficient. As such, the steering wheel angle information is incorporated into the Kalman filtering algorithm, whether the wheel speed information is below the first threshold is determined, and , in an operating condition in which the wheel speed information is below the first threshold ,the specific weight of the steering wheel angle is increased in the fusion algorithm control policy of the GNSS, IMU, wheel speed, and steering wheel angle, resulting in a more precise positioning output (e.g., increased output precision of the heading angle).

[0045] The absolute positioning device shown in FIG. 2 may be incorporated in various absolute positioning products, including but not limited to vehicle motion and position sensors (VMPS). Referring to FIG. 3, an input-output block diagram of an absolute positioning product that is located inside of a vehicle according to an embodiment of the present invention is shown. In FIG. 3, an absolute positioning product 300 receives wheel speed information from a wheel speed sensor 310, receives a steering wheel angle from a steering wheel angle sensor 320, and receives GNSS data and deviation correction data by means of an antenna 330. The absolute positioning product 300 may also include an inertial measurement unit therein. The absolute positioning product 300 further incorporates the steering wheel angle and the wheel speed information on the basis of various absolute positioning algorithms (e.g., a PPP algorithm), thereby increasing the precision and robustness of positioning at low speed, particularly in the operating condition in which the vehicle stops and goes while changing lanes. In one embodiment, the vehicle may include: a wheel speed sensor; a steering wheel angle sensor; an antenna; and an absolute positioning device (e.g., the absolute positioning device 2000 in FIG. 2), wherein the absolute positioning device 2000 is configured to receive wheel speed information from the wheel speed sensor, receive steering wheel angle information from the steering wheel angle sensor, and receive global navigation satellite system (GNSS) data and deviation correction data by means of the antenna, and performs the absolute positioning of the vehicle based on these received information.

[0046] In conclusion, the absolute positioning scheme for a vehicle in the embodiment of the present invention receives not only global navigation satellite system (GNSS) data and deviation correction data but also wheel speed information and steering wheel angle information, and determines the absolute pose of the vehicle based on the foregoing received information (which includes the wheel speed information and the steering wheel angle information). The absolute positioning scheme optimizes the problems of poor precision and unreliable positioning of absolute positioning in low-speed operating conditions by incorporating the steering wheel angle information and the wheel speed information, thereby improving the robustness of the absolute positioning product and having good engineering achievability.

[0047] Additionally, in an embodiment of the present invention, the steering wheel angle information outputted by the steering wheel angle sensor is incorporated into the current Kalman filtering algorithm in a VMPS, wherein whether the speed is below a threshold is determined according to the wheel speed information outputted by the wheel speed sensor, and , in an operating condition in which the wheel speed information is below the threshold ,the specific weight of the steering wheel angle is increased in the fusion algorithm control policy of the GNSS, IMU, wheel speed, and steering wheel angle, resulting in a more precise positioning output.

[0048] Although the above specification describes only some embodiments of the present invention, it will be appreciated by those of ordinary skill in the art that the present invention can be implemented in many other forms without departing from the spirit or scope thereof. Therefore, the illustrated examples and embodiments are regarded as illustrative and non-limiting, and the present invention may encompass various modifications and substitutions without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims

Claims1 . An absolute positioning method for a vehicle, characterized in that the method comprises: receiving global navigation satellite system (GNSS) data and deviation correction data; receiving wheel speed information and steering wheel angle information; and determining the absolute pose of the vehicle based on the global navigation satellite system (GNSS) data, the deviation correction data, the wheel speed information, and the steering wheel angle information.

2. The method according to claim 1 , wherein determining the absolute pose of the vehicle based on the global navigation satellite system (GNSS) data, the deviation correction data, the wheel speed information, and the steering wheel angle information comprises: calculating the absolute pose by fusing the global navigation satellite system (GNSS) data, the deviation correction data, an inertial navigation signal from an inertial measurement unit, the wheel speed information, and the steering wheel angle information using the Kalman filtering algorithm.

3. The method according to claim 2, wherein calculating the absolute pose by Kalman filtering of the global navigation satellite system (GNSS) data, the deviation correction data, an inertial navigation signal from an inertial measurement unit, the wheel speed information, and the steering wheel angle information comprises: determining whether the wheel speed information is below a first threshold; adjusting, based on the determination, the weight of the steering wheel angle information in the Kalman filtering algorithm; and calculating the absolute pose using the Kalman filtering algorithm on the basis of the global navigation satellite system (GNSS) data, the deviation correction data, the inertial navigation signal from the inertial measurement unit, and the adjusted steering wheel angle information.

4. The method according to claim 3, wherein adjusting, based on the determination, the weight of the steering wheel angle information in the Kalman filtering algorithm comprises:multiplying the steering wheel angle information by a first weight coefficient when the wheel speed information is below the first threshold; and multiplying the steering wheel angle information by a second weight coefficient when the wheel speed information is greater than or equal to the first threshold, wherein the first weight coefficient is greater than the second weight coefficient.

5. An absolute positioning device for a vehicle, characterized in that the device comprises: a first receiving apparatus, configured to receive global navigation satellite system (GNSS) data and deviation correction data; a second receiving apparatus, configured to receive wheel speed information and steering wheel angle information; and a determining apparatus, configured to determine the absolute pose of the vehicle based on the global navigation satellite system (GNSS) data, the deviation correction data, the wheel speed information, and the steering wheel angle information.

6. The device according to claim 5, wherein the determining apparatus comprises: a calculating unit, configured to calculate the absolute pose by fusing the global navigation satellite system (GNSS) data, the deviation correction data, an inertial navigation signal from an inertial measurement unit, the wheel speed information, and the steering wheel angle information using the Kalman filtering algorithm.

7. The device according to claim 6, wherein the calculating unit is configured to: determine whether the wheel speed information is below a first threshold; adjust, based on the determination, the weight of the steering wheel angle information in the Kalman filtering algorithm; and calculate the absolute pose using the Kalman filtering algorithm on the basis of the global navigation satellite system (GNSS) data, the deviation correction data, the inertial navigation signal from the inertial measurement unit, and the adjusted steering wheel angle information.

8. The device according to claim 7, wherein the calculating unit is configured to: multiply the steering wheel angle information by a first weight coefficient when the wheel speed information is below the first threshold; andmultiply the steering wheel angle information by a second weight coefficient when the wheel speed information is greater than or equal to the first threshold, wherein the first weight coefficient is greater than the second weight coefficient.

9. A computer storage medium, comprising an instruction, characterized in that the instruction, when run, executes the method according to any one of claims 1 to 4.

10. A computer program product, comprising a computer program, characterized in that the computer program, when executed by a processor, implements the method according to any one of claims 1 to 4.11 . A vehicle, characterized in that the vehicle comprises: a wheel speed sensor; a steering wheel angle sensor; an antenna; and the absolute positioning device according to any one of claims 5 to 8, wherein the absolute positioning device is configured to receive the wheel speed information from the wheel speed sensor, receive the steering wheel angle information from the steering wheel angle sensor, and receive the global navigation satellite system (GNSS) data and the deviation correction data by means of the antenna.

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