Combined positioning method of unmanned vehicle

Abstract

The invention relates to the technical field of unmanned vehicle positioning, in particular to a combined positioning system and method for an unmanned vehicle, and the positioning system comprises a distance measuring sensor and a wheel speed sensor which are arranged on the vehicle, and navigation grooves which are oppositely arranged in the width direction of a road. The plurality of navigation grooves are arranged at intervals along the length direction of the road, and the distance measuring sensor can measure the actual driving distance of the vehicle on the road by identifying the number of the navigation grooves through which the vehicle passes on the road, so as to correct the accumulative error of the wheel speed sensor. According to the invention, the actual driving distance of the vehicle can be measured by combining the distance measuring sensor and the navigation groove, the error of the wheel speed sensor can be corrected, and the technical effects of eliminating the accumulative error of the wheel speed sensor and improving the longitudinal positioning precision can be realized; in addition, the combined positioning system is high in environmental adaptability, capable of achieving high-precision positioning and wide in application range.

Description

Technical Field

[0001] The present invention relates to the technical field of driverless vehicle positioning, and particularly to a combined positioning system and a positioning method for a driverless vehicle. Background Art

[0002] At present, most of the positioning systems of driverless vehicles rely on satellite navigation systems, such as GPS. However, in some specific areas, such as tunnels, covered stations or urban areas with dense high-rise buildings, satellite signals are easily blocked, resulting in difficulties in ensuring positioning accuracy and reliability. In addition, the existing technology also has a problem of relying too much on a single sensor, resulting in poor system robustness. Therefore, for the technical problem that the existing technology has low positioning accuracy using sensors under the condition of being unable to rely on GPS positioning, how to provide a positioning method that can work effectively in areas without satellite signals has become an urgent goal to be achieved; for example, the existing technology only measures the vehicle speed through a wheel speed sensor arranged on the vehicle, and can calculate the driving distance of the vehicle on the road, and then obtain the longitudinal positioning of the vehicle on the road. However, during the use of the wheel speed sensor, measurement errors will occur due to reasons such as different rolling circle radii of the left and right wheels, and the cumulative error will become larger and larger due to reasons such as wheel wear and unfixed tire pressure, resulting in an increase in the longitudinal positioning error of the vehicle and an inability to guarantee the positioning accuracy. Summary of the Invention

[0003] The purpose of the present invention is to overcome the technical problem that when only a single sensor is used for positioning under the condition of no GPS positioning in the existing technology, such as a wheel speed sensor, the cumulative error of the longitudinal positioning of the vehicle on the road increases and the longitudinal positioning accuracy decreases due to the inherent measurement error of the sensor, and to provide a combined positioning system and a positioning method for a driverless vehicle.

[0004] In a first aspect, the present invention provides a combined positioning system for a driverless vehicle, including a ranging sensor and a wheel speed sensor arranged on the vehicle, and navigation slots oppositely arranged in the width direction of the road. A plurality of the navigation slots are arranged at intervals along the length direction of the road. The ranging sensor can measure the actual distance traveled by the vehicle on the road by identifying the number of the navigation slots passed by the vehicle on the road, and correct the cumulative error of the wheel speed sensor.

[0005] The present invention can combine a ranging sensor and a navigation groove to measure the actual driving distance of a vehicle, and can correct the error of the wheel speed sensor. Specifically, the navigation grooves are relatively arranged on both sides of the road. When the vehicle drives on the road and passes through the position of the navigation groove, the ranging sensor installed on the vehicle can identify the change in the road width. The position where the road width changes is the setting position of the navigation groove. Therefore, the ranging sensor can determine the number of navigation grooves passed by the vehicle. The actual distance between adjacent navigation grooves on the road and the width of the navigation groove are known parameters. The actual driving distance of the vehicle can be calculated through the distance between adjacent navigation grooves, the width of the navigation groove, and the number of navigation grooves passed by the vehicle measured by the ranging sensor. The actual driving distance can be compared with the distance measured by the wheel speed sensor, and the cumulative error of the distance measured by the wheel speed sensor can be calculated. The cumulative error can be cleared, that is, the distance measured by the wheel speed sensor can be corrected. Finally, the technical effect of eliminating the measurement error of the wheel speed sensor and improving the longitudinal positioning accuracy can be achieved. In addition, since the measurement of the longitudinal positioning information by the wheel speed sensor is smooth and continuous, continuous measurement cannot be achieved only by the ranging sensor and the navigation groove. Therefore, in the present invention, the ranging sensor, the navigation groove, and the wheel speed sensor need to be used in combination. Through the complementary fusion of data between each sensor, the system can achieve continuous and accurate positioning on the road.

[0006] Preferably, a plurality of RFID tags are arranged on the driving path of the vehicle on the road, and an RFID reader is provided on the vehicle.

[0007] Preferably, the RFID tags are respectively arranged at the parking position of the vehicle, the fork of the road, and the straight section of the road.

[0008] Here, the RFID tag is installed at the parking position to detect whether the vehicle reaches a predetermined parking position; the RFID tag is arranged before the fork diversion to inform the vehicle in advance that it is about to reach the fork, so as to perform path planning; the RFID tag is arranged after the fork confluence to inform the vehicle that the fork ends and returns to the normal driving path; the RFID tags can be evenly arranged on the straight section to continuously provide global positioning reference information.

[0009] Preferably, a gyroscope is also provided on the vehicle.

[0010] Preferably, the width of the navigation groove provided on the high-speed straight section of the road is greater than the width of the navigation groove provided at the rail gap of the road; the width of the navigation groove provided at the rail gap of the road is greater than the width of the navigation groove provided on the low-speed bend section of the road.

[0011] Here, the navigation slots at different positions on the road can be set to different widths. For example, the navigation slot on the high-speed straight section is 30 cm, the navigation slot on the low-speed curve section is 10 cm, and the navigation slot at the rail gap is 20 cm. The width of different navigation slots can be identified by a ranging sensor, which can provide a reasonable speed design value for the vehicle in different areas. For example, on the straight section, the vehicle travels at a relatively high speed, and the width of the navigation slot should be set wider to reduce the probability that a high-speed vehicle misses or fails to read the navigation slot. On the curve section, the vehicle speed is slower, and it is not easy to miss reading the navigation slot, so the width of the navigation slot can be set narrower. Because when the vehicle identifies the navigation slot, it cannot sense the normal road edge, that is, the actual width of the road. Reducing the width of the navigation slot can shorten the time for the vehicle to pass through the navigation slot, thereby reducing the time for the vehicle to lose lane information while reading the navigation slot. At the rail gap section, since there is originally a gap on the lane, the laser ranging reading will increase when the vehicle passes through the rail gap. Therefore, it is necessary to use the navigation slot to cover the rail gap. Here, the width of the navigation slot is sufficient to cover the rail gap. However, in actual engineering, the rail gap is generally located in the large-radius curve section or the straight section of the lane. Therefore, the width of the navigation slot at the rail gap can be between the width of the navigation slot on the straight section and the width of the navigation slot on the curve section.

[0012] Preferably, one ranging sensor is provided at each of the front and rear ends of the vehicle.

[0013] The ranging sensor can be installed at the front and rear ends of the vehicle, or can be installed at the center position of the vehicle. The ranging sensor can use laser ranging to measure the distances from the front end, the rear end, and the center of the vehicle body (the installation position of the laser rangefinder) to the two side road edges, and can determine the vehicle attitude through laser ranging, so as to keep the vehicle in the center of the lane.

[0014] In a second aspect, the present invention provides a combined positioning method for an autonomous vehicle, which uses the combined positioning system for an autonomous vehicle as described above, including longitudinal positioning. The longitudinal positioning includes: S1: Measuring the width of the road using the ranging sensor and identifying the number n of the navigation slots passed by the vehicle; S2: Calculating the actual distance L traveled by the vehicle on the road according to the number n of the navigation slots passed by the vehicle; S3: Comparing the actual distance L traveled by the vehicle on the road with the traveling distance L' measured by the wheel speed sensor, and calculating the cumulative error of the wheel speed sensor; S4: Clearing the cumulative error.

[0015] Preferably, the longitudinal positioning further includes: when the vehicle passes through the RFID tag set on the road, reading the encoded information of the RFID tag for positioning; here, the RFID encoded information can provide specific position information and road condition parameters (such as the curvature, slope, etc. of the road ahead).

[0016] Preferably, it further includes lateral positioning, and the lateral positioning includes: C1: measuring the distances between the vehicle and both sides of the road using the ranging sensor; C2: if the distances between the vehicle and both sides of the road are different, adjusting the driving direction of the vehicle to make the distances between the vehicle and both sides of the road consistent.

[0017] Preferably, it further includes angle positioning, and the angle positioning includes: measuring the heading angle of the vehicle using a gyroscope and determining the driving direction of the vehicle.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a combined positioning system and a positioning method for an autonomous vehicle, which can measure the actual driving distance of the vehicle by combining a ranging sensor and a navigation groove, can correct the error of the wheel speed sensor, and can achieve the technical effect of eliminating the measurement error of the wheel speed sensor and improving the longitudinal positioning accuracy; in addition, the combined positioning system of the present invention has strong environmental adaptability, and through the collaborative work of multiple sensors, the system can work normally in an environment lacking satellite signals, avoiding the dependence on a single sensor; the present invention can achieve high-precision positioning, and by using the navigation groove and RFID to combine the cumulative displacement of the wheel speed sensor, it can effectively correct errors and achieve high-precision longitudinal and lateral positioning of the vehicle; the present invention has a wide range of applications, and can be applied to autonomous vehicles in closed road scenarios, especially suitable for environments without satellite signal coverage, such as tunnels, covered station areas, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the combined positioning system of the autonomous vehicle of the present invention.

[0020] Markings in the figure: 1, navigation groove; 2, RFID tag; 3, wheel speed sensor; 4, ranging sensor; 5, gyroscope; 6, road; 7, vehicle. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The following further describes the present invention in detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following embodiments. All technologies implemented based on the content of the present invention belong to the scope of the present invention.

[0022] Unless otherwise specified, in the description of the specific embodiments of the present invention, the expression terms indicating the orientation or positional relationship such as "upper", "lower", "left", "right", "center", "inner", "outer", etc. are all based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the invention product / device / installation is commonly used. These terms of orientation or positional relationship are only for the convenience of describing the solution of the present invention or simplifying the description in the specific embodiments, so as to facilitate technicians to quickly understand the solution, rather than indicating or implying that a specific device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, it should not be construed as a limitation to the present invention.

[0023] In addition, when terms such as "horizontal", "vertical", "hanging", "parallel" appear, it does not mean that the corresponding device / component / element is required to be absolutely horizontal or vertical or hanging or parallel, but it can be slightly inclined or have a deviation. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but it can be slightly inclined. Or, it can be simply understood that the corresponding device / component / element is arranged in the directions of "horizontal", "vertical", "hanging", "parallel", etc., and can have an error / deviation of ±10% relative to the corresponding direction setting, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, more preferably within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still play its role in the solution of the present invention.

[0024] In addition, when expressions such as "first", "second", "third", etc. appear in the terms, they are only used to distinguish the description of the same or similar components, and should not be understood as emphasizing or implying the relative importance of specific components.

[0025] In addition, in the description of the embodiments of the present invention, "several", "multiple", "a number of" represent at least 2. It can be any situation such as 2, 3, 4, 5, 6, 7, 8, 9, etc., and even can be more than 9.

[0026] In addition, in the description of the technical solution of the present invention, unless otherwise clearly specified / defined / restricted, where terms such as "set", "installed", "connected", "connected", "provided with", "laid", "arranged" appear, they 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 connection means commonly used in the art such as welding, riveting, bolting, threaded connection, etc. This connection can be a mechanical connection, an electrical connection or a communication connection; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two elements.

[0027] Embodiment 1 This embodiment provides a combined positioning system for a driverless vehicle.

[0028] Figure 1 It is a schematic diagram of the combined positioning system for the driverless vehicle of the present invention.

[0029] Referring to Figure 1 , the combined positioning system for the driverless vehicle described in this embodiment may include a ranging sensor 4 and a wheel speed sensor 3 disposed on the vehicle 7, and navigation slots 1 oppositely arranged in the width direction of the road 6. A plurality of navigation slots 1 may be arranged at intervals along the length direction of the road 6. Specifically, Figure 1 As shown in , there are two pairs of navigation slots 1. The first pair of navigation slots 1 is arranged at the bend of the road 6, and the second pair of navigation slots 1 is arranged at the straight section of the road 6; the ranging sensor 4 can measure the actual distance traveled by the vehicle 7 on the road 6 by identifying the number of navigation slots 1 passed by the vehicle 7 on the road 6 (counting as 1 for a pair of navigation slots 1 oppositely arranged on both sides of the road 6), and correct the cumulative error of the wheel speed sensor 3.

[0030] The present invention can combine the ranging sensor 4 and the navigation slots 1 to measure the actual driving distance of the vehicle 7, and can correct the error of the wheel speed sensor 3. Specifically, the navigation slots 1 are oppositely arranged on both sides of the road 6. When the vehicle 7 travels on the road 6 and passes through the position of the navigation slots 1, the ranging sensor 4 installed on the vehicle 7 can identify the change in the width of the road 6. The position where the width of the road 6 changes is the installation position of the navigation slots 1. Therefore, the ranging sensor 4 can determine the number of navigation slots 1 passed by the vehicle 7. The actual distance between adjacent navigation slots 1 on the road 6 and the width of the navigation slots 1 are known parameters. The actual driving distance of the vehicle 7 can be calculated by the distance between adjacent navigation slots 1, the width of the navigation slots 1, and the number of navigation slots 1 passed by the vehicle 7 measured by the ranging sensor 4. The actual driving distance can be compared with the distance measured by the wheel speed sensor 3, and the cumulative error of the distance measured by the wheel speed sensor 3 can be calculated. Furthermore, the cumulative error can be cleared, that is, the distance measured by the wheel speed sensor 3 can be corrected. Finally, the technical effect of eliminating the measurement error of the wheel speed sensor 3 and improving the longitudinal positioning accuracy can be achieved; in addition, since the measurement of the longitudinal positioning information by the wheel speed sensor 3 is smooth and continuous, and the measurement cannot be continuous only by the ranging sensor 4 and the navigation slots 1, therefore, in the present invention, the ranging sensor 4, the navigation slots 1, and the wheel speed sensor 3 need to be used in combination. Through the complementary fusion of data between various sensors, the system can achieve continuous and precise positioning on the closed road 6.

[0031] Here, the wheel speed sensor 3 uses a grille counting method to provide the longitudinal displacement data of the vehicle 7 with a high-precision continuous pulse signal. That is to say, the longitudinal positioning information provided by the wheel speed sensor 3 is continuous, but there is an accumulated error. The data measured by the wheel speed sensor 3 can be combined with the navigation groove 1 and RFID information to effectively improve the accuracy of longitudinal positioning. The ranging sensor 4 can also measure the distance between the vehicle 7 and both sides of the road 6 by means of laser ranging, and can measure the actual driving distance of the vehicle 7 in combination with the navigation groove 1.

[0032] The longitudinal positioning information provided by the combination of the navigation groove 1 and the ranging sensor 4 can correct the accumulated error of the wheel speed sensor 3 and avoid the divergence of the error. The navigation groove 1 has high reliability and can be effectively identified by relying on laser ranging. The longitudinal positioning information provided by the combination of the navigation groove 1 and the ranging sensor 4 can only correct the error of the wheel speed sensor 3, and the specific position information cannot be provided by relying solely on the navigation groove 1 and the ranging sensor 4.

[0033] The navigation groove 1 guides the path of the vehicle 7 through a predetermined track set on the road 6. The groove body of the navigation groove 1 is made of a high-reflectivity material. For example, sandblasting is performed on the surface of the navigation groove 1 to increase the roughness of the surface of the groove body of the navigation groove 1, so as to effectively perform diffuse reflection on the laser, ensure the laser reflection efficiency of the vehicle 7, and regularly correct the longitudinal displacement of the vehicle 7. The width of the navigation groove 1 can be adjusted according to different application scenarios to adapt to different vehicle speeds and curved road sections of the road 6.

[0034] In this embodiment, a plurality of RFID tags 2 are arranged on the driving path of the vehicle 7 on the road 6, and an RFID reader is provided on the vehicle 7. Installing the RFID tag 2 at a specific position on the road 6 can be used to provide accurate information about the current position of the vehicle 7, especially at key positions such as fork roads and parking points. Here, the RFID tag 2 is made of a highly durable material and has waterproof and dustproof characteristics to adapt to the harsh outdoor environment. The RFID reader is connected to the central control system of the vehicle 7 and can read the RFID information on the road 6 and transmit it in real time. The arrangement positions of the RFID tags 2 are at key nodes, such as parking points and fork intersections, to ensure accurate information transmission at key nodes.

[0035] Optionally, the RFID tags 2 are respectively arranged at the parking position of the vehicle 7, the fork intersection of the road 6, and the straight section of the road 6.

[0036] Here, the RFID tag 2 is installed at the parking position to detect whether the vehicle 7 reaches the predetermined parking position. The RFID tag 2 is arranged before the fork road diverges to inform the vehicle 7 in advance that a fork road is approaching ahead, so as to perform path planning. The RFID tag 2 is arranged after the fork road converges to inform the vehicle 7 that the fork road ends and returns to the normal driving path. The RFID tags 2 can be evenly arranged on the straight road to continuously provide global positioning reference information.

[0037] Based on the first two methods (i.e., the navigation slot 1, the ranging sensor 4, and the wheel speed sensor 3), introducing RFID can provide accurate position information. By designing the RFID code, accurate global positioning information can be provided. Due to the influence of the RFID sensing range, although the longitudinal positioning information provided by it is global positioning, it is not accurate and cannot be used to correct errors. During the dynamic driving process of the vehicle 7, there is a certain probability of missed reading in RFID sensing, and it cannot be guaranteed that each RFID is obtained by the vehicle 7 in time. However, the missed reading of RFID does not affect the longitudinal positioning information provided by the first two positioning methods.

[0038] In this embodiment, a gyroscope 5 is also provided on the vehicle 7.

[0039] The gyroscope 5 is used to measure the yaw angle and attitude change of the vehicle 7, and can provide accurate angle information for the central control system. The gyroscope 5 ensures that the vehicle 7 maintains the correct driving direction by real-time monitoring of the angular velocity and acceleration of the vehicle 7 and combining with other sensor data.

[0040] In this embodiment, the width of the navigation slot 1 provided on the high-speed straight section of the road 6 is greater than the width of the navigation slot 1 provided at the rail gap of the road 6; the width of the navigation slot 1 provided at the rail gap of the road 6 is greater than the width of the navigation slot 1 provided on the low-speed curve section of the road 6.

[0041] Here, the navigation slots 1 at different positions on the road 6 can be set to different widths. For example, the navigation slot 1 on the high-speed straight section is 30 cm, the navigation slot 1 on the low-speed curve section is 10 cm, and the navigation slot 1 at the rail gap is 20 cm. The ranging sensor 4 can identify the widths of different navigation slots 1, and can provide reasonable speed design values for the vehicle 7 in different areas. For example, on the straight section, the vehicle travels at a relatively high speed, and the width of the navigation slot should be set wider to reduce the probability of a high-speed vehicle missing or missing the reading of the navigation slot. On the curve section, the vehicle speed is slower, and the navigation slot is not easily missed, so the width of the navigation slot can be set narrower. Because when the vehicle identifies the navigation slot, it cannot sense the normal road edge, that is, the actual width of the road. Reducing the width of the navigation slot can shorten the time for the vehicle to pass through the navigation slot, thereby reducing the time for the vehicle to lose lane information while reading the navigation slot. At the rail gap section, since there are originally gaps on the lane, the laser ranging reading will increase when the vehicle passes through the rail gap. Therefore, it is necessary to use the navigation slot to cover the rail gap. Here, the width of the navigation slot is sufficient to cover the rail gap. However, in actual engineering, the rail gap is generally located in the large-radius curve section or straight section of the lane, so the width of the navigation slot at the rail gap can be between the width of the navigation slot on the straight section and the width of the navigation slot on the curve section.

[0042] In this embodiment, a ranging sensor 4 is provided at each of the front and rear ends of the vehicle 7.

[0043] The ranging sensor 4 can measure by means of laser ranging and can be used to detect the lateral distance between the vehicle 7 and the reference object (curbstone) on the edge of the road 6. The ranging sensor 4 is installed at the front, rear and center positions of the vehicle body of the vehicle 7, can realize real-time monitoring of the environment, and ensure that the vehicle 7 always travels in the center of the lane. The data of laser ranging is combined with the central control system to perform path correction in real time to prevent the vehicle 7 from deviating from the predetermined route.

[0044] The combined positioning system of the driverless vehicle in this embodiment further includes a central controller, and the central controller is connected to each sensor to form a modular sensor system; the combined positioning system is designed as a modular sensor fusion system, and each sensor module works independently, and data sharing and fusion are centralized in the central controller. Each type of sensor independently completes the task of collecting data and then transmits the data to the central controller, and the central controller fuses and processes the data to form the final positioning information. The modular design enables the system to have stronger fault tolerance. When a certain sensor module fails, the remaining parts can still maintain operation, enhancing the robustness of the system.

[0045] The combined positioning system of the driverless vehicle in this embodiment also adopts multi-sensor data fusion, and data fusion is one of the core technologies in the combined positioning system of driverless vehicles. The data collected by laser ranging, wheel speed sensor 3, navigation slot 1, RFID and gyroscope 5 have differences and complementarities. For example, the data of the wheel speed sensor 3 can provide accurate displacement information, but there is a problem of cumulative error, and the navigation slot 1 can be used to correct this cumulative error; laser ranging can provide real-time lateral position information, while the gyroscope 5 can provide the deflection attitude of the vehicle 7. Through the complementary fusion of sensor data, the system realizes continuous and accurate positioning on the closed road 6.

[0046] The combined positioning system of the driverless vehicle in this embodiment has been designed for environmental adaptability. In the system design of the present invention, various possible road 6 environments are considered, including straight roads, curves, rail joints, fork divergences, and fork merges. The spacing of the navigation slots 1 can be adjusted according to the environmental requirements of different road sections. For example, the spacing is relatively large in the middle of the high-speed straight road to reduce the installation cost, while the spacing is reduced at low-speed curves and fork intersections to improve the accuracy. RFID tags 2 are arranged at specific parking positions and before and after the forks to further enhance the positioning ability of the vehicle 7 in special road sections.

[0047] The combined positioning system of the driverless vehicle in this embodiment adopts a fault tolerance mechanism and error correction. In practical applications, the data of each sensor inevitably has noise and errors. To improve the robustness and accuracy of the system, the present invention adopts a fault tolerance mechanism and error correction measures. The cumulative error of the wheel speed sensor 3 is periodically corrected through the navigation groove 1, the RFID tag 2 provides accurate global positioning information to assist in correcting the path, and the laser ranging is used to adjust the lateral position in real time. Through this fault tolerance mechanism, the influence of the error of a single sensor on the overall positioning accuracy can be effectively avoided.

[0048] Embodiment 2 This embodiment provides a combined positioning method for a driverless vehicle.

[0049] The combined positioning method for the driverless vehicle described in this embodiment adopts the combined positioning system of the driverless vehicle as described in Embodiment 1.

[0050] Refer to Figure 1 , the combined positioning method for the driverless vehicle in this embodiment includes longitudinal positioning, and the longitudinal positioning includes the following steps: S1: Use the distance measuring sensor 4 to measure the width of the road 6 and identify the number n of the navigation grooves 1 passed by the vehicle 7; S2: Calculate the actual distance L traveled by the vehicle 7 on the road 6 according to the number n of the navigation grooves 1 passed by the vehicle 7; S3: Compare the actual distance L traveled by the vehicle 7 on the road 6 with the traveling distance L' of the vehicle 7 measured by the wheel speed sensor 3, and calculate the cumulative error of the wheel speed sensor 3; S4: Clear the cumulative error.

[0051] In the above step S2, the calculation formula for the actual distance L traveled by the vehicle 7 on the road 6 is: ; where a n is the distance between any two adjacent navigation grooves 1 in the length direction of the road 6.

[0052] In this embodiment, the longitudinal positioning further includes: when the vehicle 7 passes by the RFID tag 2 set on the road 6, read the coding information of the RFID tag 2 for positioning.

[0053] In this embodiment, the combined positioning method for the driverless vehicle further includes lateral positioning, and the lateral positioning includes: C1: Use the distance measuring sensor 4 to measure the distances between the vehicle 7 and both sides of the road 6; C2: If the distances between the vehicle 7 and both sides of the road 6 are different, adjust the traveling direction of the vehicle 7 to make the distances between the vehicle 7 and both sides of the road 6 consistent.

[0054] In this embodiment, the combined positioning method for driverless vehicles further includes angle positioning, which includes: using a gyroscope 5 to measure the heading angle of the vehicle 7 and determine the driving direction of the vehicle 7.

[0055] The advantages of the combined positioning method for driverless vehicles in this embodiment are as follows: 1. Precision and reliability: Through the combined application of navigation slots, RFID, wheel speed sensors, lidar, and gyroscopes, the present invention achieves high-precision positioning of driverless vehicles on closed roads. The fusion of multiple sensors effectively improves the accuracy and reliability of the system. Each positioning method has its specific advantages and disadvantages, and the positioning system can combine the advantages of various positioning methods for combined positioning.

[0056] 2. Adapt to complex road conditions The combined positioning system is particularly suitable for various complex road conditions. For example, at fork roads and merging sections, RFID tags can provide location information in a timely manner for the vehicle to make path planning. The flexible spacing setting of navigation slots can meet the needs of different road types. Inside a closed road, this system can accurately identify the position of the vehicle and its surrounding environment with high precision.

[0057] 3. Reduce dependence on satellite navigation systems Traditional driverless vehicle positioning highly depends on satellite navigation systems, and satellite signals are easily blocked in special environments such as tunnels and covered stations, resulting in unreliable positioning. The combined positioning method of the present invention effectively avoids this problem through multi-sensor fusion, enabling the vehicle to accurately position in areas without satellite signals.

[0058] 4. Redundant design and safety By introducing multiple sensors, the present invention realizes redundant design to ensure that when a certain sensor fails, the remaining sensors can still provide reliable position information. For example, when the RFID reader fails, the wheel speed sensor and the navigation slot can still achieve basic longitudinal positioning. This redundant design effectively improves the safety of the system.

[0059] The application scenarios and future development of the combined positioning method for driverless vehicles in this embodiment can be reflected in the following aspects: 1. Driverless in closed parks The present invention can be applied to driverless vehicles in closed environments such as factories and warehousing parks, suitable for cargo transportation and personnel transfer. In such scenarios, the roads are relatively fixed, the layout cost of navigation slots and RFID is low, and stable positioning information can be provided. Driverless vehicles can automatically drive along a predetermined path, improving the automation level and efficiency of park logistics.

[0060] 2. Tunnels and areas without satellite signals such as covered stations In tunnels and covered stations, since reliable satellite signals cannot be received, traditional GPS-based positioning methods cannot be used. The present invention can well solve this problem. Through the combination of navigation slots and RFID tags, high-precision path tracking is achieved to ensure that vehicles can safely pass through narrow and complex environments.

[0061] 3. Intelligent transportation and smart cities In the future construction of smart cities, the application of closed roads or dedicated lanes will be more extensive. The application of driverless vehicles can reduce traffic congestion and improve traffic efficiency. The combined positioning system of the present invention can well serve this goal. By arranging navigation slots and RFID on specific roads, driverless vehicles can operate with higher safety and reliability.

[0062] 4. Logistics automation In large logistics centers, by using the combined positioning system of the present invention, automated logistics distribution can be realized. Vehicles are accurately positioned through preset navigation slots and RFID, transporting goods from the warehouse to the loading and unloading points, achieving full-process automated transportation inside and outside the warehouse, reducing labor costs and improving logistics efficiency.

[0063] In summary, the present invention provides a combined positioning system and positioning method for driverless vehicles, which can combine a ranging sensor and a navigation slot to measure the actual driving distance of the vehicle, can correct the error of the wheel speed sensor, and can achieve the technical effect of eliminating the measurement error of the wheel speed sensor and improving the longitudinal positioning accuracy; in addition, the combined positioning system of the present invention has strong environmental adaptability. Through the collaborative work of multiple sensors, the system can work normally in an environment lacking satellite signals, avoiding dependence on a single sensor; the present invention can achieve high-precision positioning. By combining the navigation slot and RFID with the cumulative displacement of the wheel speed sensor, the error can be effectively corrected to achieve high-precision longitudinal and lateral positioning of the vehicle; the present invention has a wide range of applications and can be applied to driverless vehicles in closed road scenarios, especially suitable for environments without satellite signal coverage, such as tunnels, covered station areas, etc.

[0064] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A combined positioning system for an autonomous vehicle, characterized in that It includes a ranging sensor (4) and a wheel speed sensor (3) provided on a vehicle (7), and navigation grooves (1) oppositely arranged in the width direction of a road (6). A plurality of the navigation grooves (1) are arranged at intervals along the length direction of the road (6). The ranging sensor (4) can measure the actual distance traveled by the vehicle (7) on the road (6) by identifying the number of the navigation grooves (1) passed by the vehicle (7) on the road (6), and correct the cumulative error of the wheel speed sensor (3).

2. The combined positioning system for the driverless vehicle according to claim 1, wherein A plurality of RFID tags (2) are arranged on the traveling path of the vehicle (7) on the road (6), and an RFID reader is provided on the vehicle (7).

3. The combined positioning system for the driverless vehicle according to claim 2, characterized in that, The RFID tags (2) are respectively arranged at the parking position of the vehicle (7), the fork of the road (6), and the straight section of the road (6).

4. The combined positioning system for a driverless vehicle according to claim 1, characterized in that, A gyroscope (5) is also provided on the vehicle (7).

5. The combined positioning system for a driverless vehicle according to claim 1, characterized in that, The width of the navigation groove (1) provided on the high-speed straight section of the road (6) is greater than the width of the navigation groove (1) provided at the rail gap of the road (6); the width of the navigation groove (1) provided at the rail gap of the road (6) is greater than the width of the navigation groove (1) provided on the low-speed bend section of the road (6).

6. The combined positioning system for the driverless vehicle according to claim 1, characterized in that, One ranging sensor (4) is provided at each of the front and rear ends of the vehicle (7).

7. A combined positioning method for an autonomous vehicle, characterized in that, The combined positioning system of the driverless vehicle according to any one of claims 1 to 6 is adopted, including longitudinal positioning, and the longitudinal positioning includes: S1: Measuring the width of the road (6) by using the ranging sensor (4), and identifying the number n of the navigation grooves (1) passed by the vehicle (7). S2: Calculating the actual distance L traveled by the vehicle (7) on the road (6) according to the number n of the navigation grooves (1) passed by the vehicle (7). S3: Comparing the actual distance L traveled by the vehicle (7) on the road (6) with the traveling distance L' of the vehicle (7) measured by the wheel speed sensor (3), and calculating the cumulative error of the wheel speed sensor (3). S4: Clearing the cumulative error to zero.

8. The combined positioning method for a driverless vehicle according to claim 7, wherein The longitudinal positioning further includes: When the vehicle (7) passes the RFID tag (2) provided on the road (6), reading the encoded information of the RFID tag (2) for positioning.

9. The combined positioning method for the driverless vehicle according to claim 7, wherein, It further includes lateral positioning, and the lateral positioning includes: C1: Measuring the distances between the vehicle (7) and both sides of the road (6) by using the ranging sensor (4). C2: If the distances between the vehicle (7) and both sides of the road (6) are different, adjusting the traveling direction of the vehicle (7) to make the distances between the vehicle (7) and both sides of the road (6) consistent.

10. The combined positioning method for a driverless vehicle according to any one of claims 7 to 9, characterized in that, It further includes angle positioning, and the angle positioning includes: Measuring the heading angle of the vehicle (7) by using the gyroscope (5) and determining the traveling direction of the vehicle (7).

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