Position estimation system and method

Abstract

To provide technique capable of improving accuracy of position estimation of a vehicle by estimating a traveling road on the basis of various information (surrounding environment information) acquired from the surrounding environment of the vehicle.SOLUTION: A position estimation system comprises: a first position estimation part which obtains a first estimated current position by estimating a current position of a vehicle traveling on a traveling road; a traveling road estimation part which obtains an estimated traveling road by estimating the traveling road on which the vehicle is traveling on the basis of surrounding environment information detected by a sensor; and a position correction part which obtains a first corrected current position by correcting the first estimated current position on the basis of the estimated traveling road. The position correction part can set the closest point to the first estimated current position on the estimated traveling road as the first corrected current position.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a position estimation system and method. [Background technology]

[0002] To realize obstacle detection and advanced train control, which are basic functions of automated railway operation, it is necessary to estimate the vehicle's position with high accuracy. Conventional methods include installing multiple ground coils that record accurate absolute positions on the tracks and correcting the position every time a ground coil passes. However, the installation and maintenance costs of ground coils are high, so position estimation using the Global Navigation Satellite System (GNSS) is being considered as an alternative method.

[0003] As a GNSS-based position estimation technology, a method called map matching, which corrects the position coordinates measured by GNSS to the nearest route, is widely known in car navigation systems, etc. However, when map matching is used to estimate the position of railway vehicles, there is a possibility that a train running on a down line will be erroneously corrected to an up line due to GNSS measurement errors, and new information and additional processing will be required to correctly recognize the train.

[0004] Patent Document 1 describes a method for determining the nearest point on a travel route using position coordinates measured from GNSS, in which the travel route is identified using the track and track number information of the train in operation, and the position is corrected to the route. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2013-99976 A Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Document 1, the travel route is estimated based on specific information (e.g., a train schedule) that is determined in advance, such as the train's location on the track at a depot or station. However, in this case, if a system that acquires information from an external source, such as a traffic management system, is constructed, the system becomes large-scale, and the system development costs and the scale of repairs become large. In such a case, it is not possible to configure a position estimation system linked to a traffic management system. In addition, it is possible that the train schedule cannot be acquired when estimating the vehicle's position. Even if the train schedule can be acquired, the train's track and track number information may be suddenly changed due to passengers or other train disruptions or delays, and so there is a problem that the acquired train's track and track number information is not accurate and the vehicle's travel route cannot be accurately identified. Therefore, the present invention aims to provide a technology that can improve the accuracy of estimating a vehicle's position by estimating the driving path based on various information obtained from the vehicle's surrounding environment (hereinafter referred to as "surrounding environment information"). [Means for solving the problem]

[0007] In order to solve the above problems, one representative position estimation system of the present invention includes a first position estimation unit that estimates the current position of a vehicle traveling on a traveling path to obtain a first estimated current position, a traveling path estimation unit that estimates the traveling path on which the vehicle is traveling using surrounding environment information detected by a sensor to obtain an estimated traveling path, and a position correction unit that corrects the first estimated current position based on the estimated traveling path to obtain a first corrected current position. Effect of the Invention

[0008] According to the present invention, the driving path is estimated based on various information (surrounding environment information) obtained from the surrounding environment, such as the presence or absence of buildings alongside the driving path and the positional relationship of the vehicle ahead, without relying on predetermined specific information such as a train schedule, and the accuracy of position estimation can be improved by correcting the vehicle's current position based on the estimated driving path. Problems, configurations and effects other than those described above will become apparent from the description of the following embodiments. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a configuration diagram of a position estimation system in the first embodiment. [Diagram 2] FIG. 2 is a diagram showing an image of a road and route information. [Diagram 3] FIG. 3 is a conceptual diagram showing how the driving path is estimated based on the presence or absence of buildings beside the road and the position of the vehicle ahead. [Figure 4] FIG. 4 is a conceptual diagram showing how the estimated current position is corrected to the estimated travel route to obtain a corrected current position. [Diagram 5] FIG. 5 is a flowchart showing a procedure for estimating and correcting the current position of the vehicle in the first embodiment. [Figure 6] FIG. 6 is a configuration diagram of a position estimation system in the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [First embodiment] In this embodiment, a method is described in which a road is estimated from surrounding environment information such as the presence or absence of buildings beside the road and the positional relationship of the vehicle ahead, and the current position of the vehicle is corrected based on the estimated road. In this embodiment, a road is defined by the line on which the vehicle is traveling and the track number of the line.

[0011] First, the configuration of the position estimation system 100 and the role of each component are described. FIG. 1 is a configuration diagram of the position estimation system 100 in the first embodiment. The position estimation system 100 includes a first position estimation unit 101, a travel path coordinate storage unit 102, a travel path estimation unit 103, and a position correction unit 104. The first position estimation unit 101 acquires first measured position information, and the travel path estimation unit 103 acquires surrounding environment information from a vehicle 105. The position estimation system 100 may be installed on the ground or on a vehicle, and some of the components may be installed on the ground and the rest on the vehicle. The position estimation system 100 and the vehicle 105 may be connected by wireless communication when the position estimation system 100 is on the ground, and may be connected by wireless communication or wired communication when the position estimation system 100 is on the vehicle.

[0012] (system) The first position estimation unit 101 has a function of estimating the current position of the vehicle 105 traveling on a travel path (hereinafter, the current position of the vehicle 105 estimated by the position estimation unit is referred to as the "estimated current position"). As a method of estimating the current position, a method of estimating the position using first measured position information by satellite positioning such as GNSS can be mentioned. Note that the method of estimating the position is not limited to satellite positioning, and other measured position information from a sensor such as a LIDAR or a camera that measures the surrounding environment around the vehicle as two-dimensional or three-dimensional coordinate information may also be used. In this case, SLAM (Simultaneous Localization and Mapping) is used, which is a method of creating surrounding shape data at each position from a travel distance calculated from the difference between surrounding shape data of a position before movement and a current position.

[0013] The travel path coordinate storage unit 102 has a function of storing route information of travel paths measured in advance. Examples of the route information of travel paths include map information (coordinate point sequence data such as latitude and longitude at each point). FIG. 2 is a diagram showing an image of a travel path and route information. FIG. 2(a) shows an image of a travel path (an example in which three travel paths 1 to 3 are arranged side by side), and FIG. 2(b) shows map information for each travel path. Note that it is assumed that the more precisely the coordinate point sequence data of the map information is measured, the higher the position accuracy will be, and the intervals may be set according to the required position accuracy.

[0014] The travel path estimation unit 103 has a function of estimating the travel path on which the vehicle 105 is traveling based on various information (surrounding environment information) acquired from the surrounding environment of the vehicle (hereinafter, the travel path estimated by the travel path estimation unit 103 is referred to as the "estimated travel path"). The surrounding environment information is acquired from the inside or surrounding environment of the travel path, and is not particularly limited as long as it enables the vehicle to identify the travel path on which the vehicle is traveling among a plurality of travel paths, but information related to man-made objects that change little over time is preferable. For example, the presence or absence of buildings beside the travel path and the positional relationship of the vehicle to surrounding vehicles are considered. Other examples include signs, signals, utility poles, overhead lines, inner walls of tunnels, and platform doors placed on platforms beside the travel path. In addition, information on the estimated travel path may include, for example, information on which line and which track number of the line the vehicle is traveling on.

[0015] Sensing technology for advanced driving assistance systems (ADAS) can be used to detect surrounding environment information such as the presence or absence of buildings beside the road and the position of the vehicle ahead. For example, image data, distance data, position data, etc. can be detected using on-board sensors such as cameras and LIDAR that measure the surrounding environment around the vehicle in two or three dimensions.

[0016] Fig. 3 is a conceptual diagram of how the driving lane is estimated based on the presence or absence of buildings beside the driving lane and the positional relationship of the vehicle ahead. As shown in Fig. 3, for example, when traveling on two driving lanes, if there is another vehicle ahead on the right, it is determined that the vehicle ahead is traveling on the right driving lane 2, and the vehicle itself is estimated to be traveling on the left driving lane 1. Alternatively, if a building on the left side is detected within a specified distance from the vehicle, it is estimated to be traveling on the left driving lane 1. In addition, by combining multiple pieces of information obtained from the surrounding environment, it is possible to estimate the driving path with higher accuracy. For example, by combining vehicle detection information on the right front with information on the presence or absence of a building on the left side within a specified distance, or by combining information on the presence or absence of a building on the left side within a specified distance with information on whether a building on the right side is more than a specified distance away, it is expected that the estimation accuracy will improve. The estimation of the driving route is performed continuously while driving, and when the driving route is changed, such as when changing lanes, the changed driving route is output.

[0017] The position correction unit 104 has a function of estimating the travel path and then correcting the point on the estimated travel path that is closest to the estimated current position as the current position of the vehicle (hereinafter, the current position on the estimated travel path obtained by correcting the estimated current position is referred to as the "corrected current position"). FIG. 4 is a conceptual diagram of correcting the estimated current position on the estimated travel path to obtain the corrected current position. In this figure, the travel path estimation unit 103 estimates the travel path 2 as the travel path, and then outputs a corrected current position (black square mark in the figure) that is corrected from the estimated current position (white square mark in the figure) estimated by the first position estimation unit 101 to the closest point on the travel path 2, which is the estimated travel path. The corrected current position can be displayed on a display unit (not shown) provided on the vehicle or on the ground. The estimated current position and the corrected current position in the first embodiment may also be referred to as the first estimated current position and the first corrected current position, respectively.

[0018] The vehicle 105 is a vehicle that travels on a fixed route, such as an automobile, a train, a bus, or an LRT (Light Rail Transit).

[0019] (flowchart) Next, a procedure for estimating and correcting the current vehicle position described above will be described with reference to Fig. 5. Fig. 5 is a flow chart showing the procedure for estimating and correcting the current vehicle position in the first embodiment.

[0020] In step S11, the first position estimation unit 101 estimates the current position of the vehicle (estimated current position). In step S12, the travel path estimation unit 103 estimates the travel path from surrounding environment information such as the presence or absence of buildings beside the travel path and the positional relationship of the vehicle ahead (estimated travel path). In step S13, the position correction unit 104 acquires coordinate point sequence data of the estimated driving route from the driving route coordinate storage unit 102. In step S14, the position correction unit 104 corrects the current position of the vehicle 105 to the closest point on the travel route from the estimated current position (corrected current position).

[0021] If an error occurs in the estimation of the driving route in step S12, a setting may be adopted in step S14 in which the estimated current location in step S11 is regarded as the corrected current location as is, or a setting may be adopted in which the estimation of the driving route (step S12) is redone.

[0022] As described above, in this embodiment, the driving path is estimated from surrounding environment information such as the presence or absence of buildings alongside the driving path and the positional relationship of the vehicle ahead, and the point on the driving path closest to the estimated current position is corrected as the vehicle's current position, thereby improving the accuracy of position estimation without relying on predetermined specific information such as a train schedule. In addition, since the route is estimated based on various surrounding environment information, even if one piece of information (for example, the position of the vehicle ahead) is missing, it is possible to estimate using other information (for example, the presence or absence of buildings), and the accuracy can be improved by combining multiple pieces of information (for example, combining the position information of the vehicle ahead and the presence or absence of buildings). By selecting and discarding information that is useful for estimation judgment according to the surrounding environment of the route, it is possible to improve the estimation accuracy by using information that is appropriate for the environment.

[0023] [Second embodiment] This embodiment differs from the first embodiment in that a second position estimation unit 206 that acquires second measured position information is added, and the estimated current position of the vehicle is corrected by a position correction unit 204. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0024] FIG. 6 is a configuration diagram of a position estimation system 200 in the second embodiment.

[0025] The second position estimation unit 206 has a function of estimating a position as a device different from the first position estimation unit 101. The second position estimation unit 206 performs position estimation using second measured position information different from first measured position information obtained from a sensor such as an accelerometer and / or a speedometer, an IMU, or a LIDAR. When separate information processing can be performed on the first and second measured position information, the first position estimation unit 101 and the second position estimation unit 206 do not necessarily need to be different devices.

[0026] The position correction unit 204 has a function of comparing the point on the estimated travel route closest to the first estimated current location with the point on the estimated travel route closest to the second estimated current location by the second position estimation unit, and discarding the information on the first and second estimated current locations if the difference is greater than a predetermined value. This reduces the probability of erroneous position estimation.

[0027] When the information on the estimated current location is discarded as described above, a setting may be adopted in which the first estimated current location is regarded as the estimated current location of the vehicle as is, or a setting may be adopted in which a display indicating that the estimated current location is unknown is output. Furthermore, after the information on the estimated current location is discarded, it is also possible to set the above-mentioned comparison to be repeated until the estimated current location falls below a predetermined value. In addition, a setting may be adopted in which if the point on the estimated travel route closest to the first estimated current location and the point on the estimated travel route closest to the second estimated current location are equal to or smaller than a predetermined value, the former is deemed to be the estimated current location of the vehicle, or a setting may be adopted in which the average point of the two is deemed to be the estimated current location.

[0028] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present invention.

[0029] The following are some possible embodiments of the present invention, but the present invention is not limited to these. (Aspect 1) a first position estimation unit that estimates a current position of a vehicle traveling on a travel path to obtain a first estimated current position; a travel path estimation unit that estimates a travel path on which the vehicle is traveling by using surrounding environment information detected by a sensor, and obtains an estimated travel path; a position correction unit that corrects the first estimated current position based on the estimated travel route to obtain a first corrected current position. (Aspect 2) 2. The position estimation system according to aspect 1, wherein the position correction unit determines a point on the estimated travel route that is closest to the first estimated current position as the first corrected current position. (Aspect 3) 3. The position estimation system according to aspect 1 or 2, wherein the surrounding environment information includes information regarding the presence or absence of buildings beside a roadway. (Aspect 4) 4. The position estimation system according to any one of aspects 1 to 3, wherein the surrounding environment information includes information regarding a positional relationship of the vehicle with respect to surrounding vehicles. (Aspect 5) 5. The position estimation system according to any one of aspects 1 to 4, further comprising a travel path information storage unit that stores route information of a travel path. (Aspect 6) 6. The position estimation system according to aspect 5, wherein map information is used as the route information of the travel path. (Aspect 7) 7. The position estimation system according to any one of aspects 1 to 6, wherein the estimated travel route is specified by a line and a track number of the line. (Aspect 8) A second position estimation unit that estimates a current position of the vehicle traveling on the travel path to obtain a second estimated current position, The position estimation system according to any one of aspects 1 to 7, characterized in that the position correction unit corrects the second estimated current position based on the estimated driving route to obtain a second corrected current position, and further discards information of the first and second estimated current positions if a difference between the first corrected current position and the second corrected current position is greater than a predetermined value. (Aspect 9) A position estimation system as described in aspect 8, characterized in that the first position estimation unit and the second position estimation unit determine the first and second estimated current positions using different first measured position information and second measured position information, respectively. (Aspect 10) A step of estimating a current position of a vehicle traveling on a travel path to obtain a first estimated current position in a first position estimation unit; A travel path estimating unit estimates a travel path on which the vehicle is traveling using surrounding environment information detected by a sensor to obtain an estimated travel path; and a step of: in a position correction unit, correcting the first estimated current position based on the estimated travel route to obtain a first corrected current position. [Explanation of symbols]

[0030] 100, 200... position estimation system, 101... first position estimation unit, first position estimation unit 102: Travel path coordinate storage unit, 103: Travel path estimation unit 104, 204... position correction unit, 105... vehicle 206...Second position estimation unit

Claims

1. a first position estimation unit that estimates a current position of a vehicle traveling on a travel path to obtain a first estimated current position; a travel path estimation unit that estimates a travel path on which the vehicle is traveling by using surrounding environment information detected by a sensor, and obtains an estimated travel path; a position correction unit that corrects the first estimated current position based on the estimated travel route to obtain a first corrected current position.

2. 2. The position estimation system according to claim 1, wherein said position correction unit determines a point on said estimated travel route that is closest to said first estimated current position as said first corrected current position.

3. 3. The position estimation system according to claim 1, wherein the surrounding environment information includes information regarding the presence or absence of buildings beside the roadway.

4. 3. The position estimation system according to claim 1, wherein the surrounding environment information includes information regarding a positional relationship of the vehicle with respect to surrounding vehicles.

5. 3. The position estimation system according to claim 1, further comprising a travel path information storage unit that stores route information of a travel path.

6. 6. The position estimation system according to claim 5, wherein map information is used as the route information of the travel route.

7. 3. The position estimation system according to claim 1, wherein the estimated travel route is specified by a line and a track number of the line.

8. A second position estimation unit that estimates a current position of the vehicle traveling on the travel path to obtain a second estimated current position, 2. The position estimation system according to claim 1, wherein the position correction unit corrects the second estimated current position based on the estimated traveling route to obtain a second corrected current position, and further discards information on the first and second estimated current positions when a difference between the first corrected current position and the second corrected current position is greater than a predetermined value.

9. 9. The position estimation system according to claim 8, wherein the first position estimation unit and the second position estimation unit determine the first and second estimated current positions using different first measured position information and second measured position information, respectively.

10. A step of estimating a current position of a vehicle traveling on a travel path to obtain a first estimated current position in a first position estimation unit; A travel path estimating unit estimates a travel path on which the vehicle is traveling using surrounding environment information detected by a sensor to obtain an estimated travel path; and a step of: in a position correction unit, correcting the first estimated current position based on the estimated travel route to obtain a first corrected current position.

Images