Patent Publication Number: US-2021180959-A1

Title: Map generation system, in-vehicle device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is the U.S. bypass application of International Application No. PCT/JP2019/033314 filed Aug. 26, 2019 which designated the U.S. and claims priority to Japanese Patent Application Nos. 2018-163077, filed Aug. 31, 2018 and 2019-141129, filed on Jul. 31, 2019 the contents of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     Technical Field 
     The present disclosure relates to a map generation system and an in-vehicle device. 
     Description of the Related Art 
     As an indicator for determining quality of a map, evaluation based on freshness of the map is generally known. Such an indicator is insufficient to guarantee that the map allows a system to actually operate properly. 
     SUMMARY 
     A first aspect of the present disclosure is a method executed by at least one processor in accordance with assisted driving or automatic driving of a vehicle. The method includes: acquiring road information from one or more sensors of the vehicle; acquiring a temporary map; calculating a difference amount A between route information generated from the temporary map and route information generated from the road information; and outputting a determination result indicating that quality of the temporary map is acceptable when the difference amount A is a predetermined value or less. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above object and other objects, features, and advantages of the present disclosure will be more apparent from the following detailed description with reference to the accompanying drawings, wherein: 
         FIG. 1  is a block diagram showing a schematic configuration of a map generation system according to an embodiment; 
         FIG. 2  is a sequence diagram showing an outline of a process in the map generation system; 
         FIG. 3  is a sequence diagram showing an outline of a process in the map generation system; 
         FIG. 4  is a sequence diagram showing an outline of a process in the map generation system; and 
         FIG. 5  shows an example of a changed portion of a temporary map. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As an indicator for determining quality of a map, evaluation based on freshness of the map is generally known. Such an indicator is insufficient to guarantee that the map allows a system to actually operate properly. There is a method, for example, patent literature, U.S. Pat. No. 8,918,277 B discloses a technique in which sample evaluation of map data is performed by using, for example, a simulator that simulates an actual system, a test vehicle which is an actual vehicle or the like equipped with the system. However, such a method is insufficient to determine the actual nature of data sequentially updated using probe data. 
     Embodiments of the present disclosure will be described below with reference to the drawings. In the following description, the same elements as those described previously are denoted by the same reference numerals and the description thereof is omitted. 
     EMBODIMENT 
     As shown in  FIG. 1 , a map generation system  1  according to the embodiments includes a server  10 , an in-vehicle device  20 , and a road information providing vehicle  30 . The server  10 , the in-vehicle device  20 , and the road information providing vehicle  30  are communicably connected to each other via a communication unit  12  and a communication unit  22  so as to be able to transmit and receive data through a radio communication network  40 . 
     The server  10  includes a control unit  11  and the communication unit  12 . The control unit  11  and the communication unit  12  are connected to each other via a data communication line  13 . The control unit  11  is composed of, for example, a processor including a CPU, a RAM, a ROM, an I/O, and the like. The control unit  11  includes a map generation unit  11   a  and a quality check result reflection unit  11   b.    
     The communication unit  12  transmits data information including map information, and the like to the in-vehicle device  20  of a verification vehicle and the road information providing vehicle  30  via the radio communication network  40 . The control unit  11  executes, for example, a program stored in the ROM to implement functional units such as the map generation unit  11   a  and the quality check result reflection unit  11   b . The map data may be, for example, data including coordinate information on various features that are present along a road. In an aspect, such map data corresponds to data for causing a vehicle to autonomously travel along a road. 
     The map generation unit  11   a  generates a temporary map and an official map on the basis of acquired map data. The quality check result reflection unit  11   b  updates the map information on the basis of acquired determination information on the temporary map. Furthermore, on the basis of the acquired determination information on the temporary map, the quality check result reflection unit  11   b  generates a signal for causing a distributed temporary map to be an official map. The quality check result reflection unit  11   b  transmits the official map and the signal for causing the temporary map to be an official map to the in-vehicle device  20  of the verification vehicle or the road information providing vehicle  30  via the communication unit  12 . 
     The in-vehicle device  20  is installed in a verification vehicle that verifies a temporary map. The in-vehicle device  20  includes a control unit  21 , the communication unit  22 , and sensors. The sensors are devices capable of acquiring information necessary for each of assisted driving and automatic driving of the vehicle. The sensors include a road information acquisition unit  23  that recognizes a condition of a road and road surroundings, a steering angle sensor  24  that detects a steering angle of a steering wheel or a steered wheel of the vehicle, a vehicle speed sensor  25  that detects a vehicle speed, a satellite positioning system  26  that performs position measurement and time distribution by using a signal emitted from an artificial satellite, and an inertia sensor  27  that detects inertia of the vehicle. 
     Examples of the road information acquisition unit  23  include a camera, a LiDAR (light detection and ranging or laser imaging detection and ranging), and a millimeter wave radar. The above sensors are presented as examples, and the in-vehicle device  20  may be provided with other appropriate sensors required for the map generation system  1 . 
     The in-vehicle device  20  detects an accurate position of the vehicle in chronological order on the basis of information acquired from the sensors. Furthermore, the in-vehicle device  20  recognizes information on the road surroundings, for example, recognizes a road condition such as a lane or recognizes a feature such as a roadside strip or a sign. 
     The control unit  21 , the communication unit  22 , and the sensors are connected to each other via a data communication line  28 . The data communication line  28  is, for example, an in-vehicle network such as an in-vehicle LAN or CAN. 
     The control unit  21  is composed of a processor including a CPU, a RAM, a ROM, an I/O unit, and the like. The control unit  21  includes an assisted driving control unit  21   a  that controls assisted driving, automatic driving, or the like of the vehicle, a map information generation unit  21   b  that generates map information, a difference calculation unit  21   c  that calculates an amount of difference between generated various types of route information, and a map quality determination unit  21   d  that determines quality of a map. 
     The control unit  21  executes, for example, a program stored in the ROM by the CPU to implement functions of functional units such as the assisted driving control unit  21   a , the map information generation unit  21   b , the difference calculation unit  21   c , and the map quality determination unit  21   d  and control the communication unit  22 , the road information acquisition unit  23 , the steering angle sensor  24 , the vehicle speed sensor  25 , the satellite positioning system  26 , the inertia sensor  27 , and the like. 
     Although illustration is omitted, the road information providing vehicle  30  has the same configuration as that of the in-vehicle device  20  shown in  FIG. 1 , that is, the road information providing vehicle  30  includes a control unit including an assisted driving control unit, a map information generation unit, a difference calculation unit, and a map quality determination unit, a communication unit, a road information acquisition unit, a steering angle sensor, a vehicle speed sensor, a satellite positioning system, an inertia sensor, and the like. The road information providing vehicle  30  transmits and receives various types of data information to the server  10  via the radio communication network  40 . Three vehicles, i.e., vehicles X, Y, and Z are presented as examples of the road information providing vehicle  30 , but a single vehicle or a larger number of vehicles may be employed as the road information providing vehicle  30 . 
     As shown in  FIG. 2 , in the map generation system  1 , the road information providing vehicle  30  acquires road information, for example, from an image detected by the road information acquisition unit of the road information providing vehicle  30  (S 101 ). The road condition includes not only road information on a road on which the vehicle travels but also a condition of a roadside strip and information on features such as a road sign, a bridge, a station, and a store, landmarks, and the like. 
     The landmarks include, for example, traffic signals, poles, commercial signboards, stores, symbolic buildings such as historical buildings, road markings, and the like. The poles include streetlights, mirrors, utility poles, and the like. The road markings indicate markings painted on a road surface mainly for traffic control and traffic regulation. The road markings include, for example, lane boundary lines (e.g., division lines, lane marks) indicating a boundary between lanes, pedestrian crossings, stop lines, zebra zones, safety zones, regulation arrows, and the like. 
     The road markings also include road studs such as chatter bars and Botts&#39; dots. Furthermore, the landmarks may be signboards corresponding to traffic signs such as regulatory signs, guide signs, warning signs, and indication signs. The guide signs indicate direction signboards, signboards that display an area name, signboards that display a road name, advance notice signboards that provide advance notice of the entrance or exit of an expressway, a service area, or the like. 
     Map coordinate data on a road and a feature and information on a change in feature are detected from an official map distributed to the road information providing vehicle  30  and a difference between route information generated from the official map and a road condition acquired by the sensors such as a camera. The map coordinate data and the feature change information are transmitted to the server  10  (S 101 ). 
     The above process performed in the road information providing vehicle  30  may be performed while assisted driving or automatic driving (hereinafter referred to as assisted driving or the like) of the vehicle is performed or while no assisted driving or the like is performed. When no assisted driving or the like is performed, operation such as generation of a route based on the official map described above is performed in the background of operation of the assisted driving control unit. 
     Next, when a predetermined number of pieces of map coordinate data and feature change information acquired from the plurality of road information providing vehicles  30  are accumulated, the server  10  generates a temporary map (S 102 ). The temporary map has not been verified in actual use; thus, in the temporary map, a changed portion, for example, a portion at which a change in feature has occurred is provided with a flag QA=0 that means that the portion is unverified. The generated temporary map is transmitted to the verification vehicle (S 102 ). 
     A portion that has been verified and for which no problems were found is provided with a flag QA=1 that means that the portion is verified. The QA frag may be provided to each feature such as a landmark, or may be provided to each of groups obtained by dividing a road into predetermined sections. 
     In the verification vehicle that has received the temporary map, the in-vehicle device  20  of the verification vehicle performs verification of the temporary map. Specifically, the in-vehicle device  20  generates first route information in a shadow mode by using the temporary map (S 103 ). The first route information is generated by the assisted driving control unit  21   a  of the in-vehicle device  20  of the verification vehicle. 
     The shadow mode means an operation mode in which the assisted driving control unit  21   a  generates route information for assisted driving or the like but no assisted driving or the like of the vehicle using the generated route information is performed. In this case, when the verification vehicle performs assisted driving or the like, assisted driving or the like is performed according to a route generated on the basis of an official map that has been officially distributed to the verification vehicle at this time point. That is, while assisted driving or the like based on the official map is performed, verification is performed in the shadow mode by using the route information generated from the temporary map. 
     In the verification vehicle, the in-vehicle device  20  generates second route information on the basis of information acquired by the sensors including the road information acquisition unit  23 , the steering angle sensor  24 , the vehicle speed sensor  25 , the satellite positioning system  26 , and the inertia sensor  27  (S 104 ). The second route information is generated by the assisted driving control unit  21   a . S 103  and S 104  are both performed in the shadow mode. 
     Next, the difference calculation unit  21   c  calculates a difference amount A between the first route information and the second route information (S 105 ). The difference amount A is caused by, for example, a change in feature such as an increase or decrease in signs, a detour from the route due to construction, or the like. At this point, the map information generation unit  21   b  generates difference map information based on the difference amount A. The difference map information may be generated, for example, as coordinate data on a portion at which a change in feature has occurred or coordinate data on an alternative route. 
     Next, the map quality determination unit  21   d  determines quality of the temporary map (S 106 ). The quality of the temporary map is determined on the basis of whether the difference amount A between the first route information and the second route information is a predetermined value or less. When the difference amount A is the predetermined value or less, the quality of the temporary map is determined to be acceptable, and when the difference amount A exceeds the predetermined value, the quality of the temporary map is determined to be unacceptable. The in-vehicle device  20  transmits a quality determination result of the temporary map to the server  10  (S 106 ). At this time, the difference map information and coordinate data on the portion provided with QA=1 may be transmitted to the server  10 . 
     When the quality of the temporary map is acceptable, in the server  10  that has acquired the quality determination result of the temporary map, the quality check result reflection unit  11   b  updates an official map using the temporary map (S 107 ). Furthermore, the quality check result reflection unit  11   b  transmits a signal for updating an official map using the temporary map to the in-vehicle device  20  of the verification vehicle without transmitting official map data to the in-vehicle device  20  of the verification vehicle (S 107 ). In the in-vehicle device  20  that has received the signal for updating an official map using the temporary map, the official map is updated to be the temporally map. At this time, in the in-vehicle device  20 , an official map may be updated using the temporary map by reflecting the map coordinate data on the portion of the temporary map for which the quality determination result is QA=1. 
     In this manner, no official map including an enormous amount of data needs to be distributed again to the verification vehicle that already has the temporary map, leading to a reduction in the amount of data to be transmitted. In the verification vehicle that has received such a signal, an official map is updated to be the temporary map, and after that, assisted driving or the like is performed on the basis of the official map. Furthermore, the server  10  distributes, to the road information providing vehicle  30 , the official map generated by updating (S 107 ). 
     Verification of the temporary map described above may be performed so that, for example, when the temporary map is verified at an automatic driving level  2  or lower and the verification result indicates that the quality of the temporary map is acceptable, the temporary map after verification is applied to an automatic driving level  3 , which is higher by one level than the automatic driving level at which the distributed temporary map has been verified. Thus, the temporary map data may include information on an automation level to which the temporary map can be applied. As described above, verification of the temporary map may be performed so that when the temporary map is verified at a lower automatic driving level and the verification result indicates that the quality of the temporary map is acceptable, the temporary map after verification is applied to an automatic driving level higher by one level than the automatic driving level at which the temporary map had previously been verified. 
       FIG. 3  shows a modification of the processing flow described in  FIG. 2 . In the verification vehicle, after the first route information is generated in the shadow mode by using the temporary map (S 103 ), third route information which is information on a route on which the verification vehicle actually travels is specified and stored by using the official map at this time point and route information generated from information acquired from the sensors such as the road information acquisition unit  23 , the vehicle speed sensor  25 , the satellite positioning system  26 , and the inertia sensor  27  (S 204 ). Thus, at S 204 , the third route information which is information on a route on which the verification vehicle actually travels by assisted driving or the like using the in-vehicle device  20  of the verification vehicle is stored. At S 204 , the third route information may be information on a route on which the verification vehicle actually travels without being controlled by assisted driving or the like. 
     Next, a difference amount B between the first route information and the third route information is calculated (S 205 ), and quality of the temporary map is determined (S 106 ). The rest of the processing flow is the same as that shown in  FIG. 2 . The processing flow of the modification shown in  FIG. 3  can reflect a change in the road condition of the actual travel route, and the like. 
       FIG. 4  shows a processing flow after the official map is updated to be the temporary map (S 107 ), i.e., a processing flow continued from the processing flow in  FIG. 2 or 3 . In the processing flow shown in  FIG. 4 , the road information providing vehicle  30  performs verification of the official map. The road information providing vehicle  30  may be equipped with an assisted driving control system that performs assisted driving of the vehicle or equipped with an automatic driving control system that automatically drives the vehicle. 
     The road information providing vehicle  30  to which the official map has been distributed from the server  10  generates fourth route information on the basis of the official map (S 301 ). In this case, it does not matter whether the road information providing vehicle  30  actually performs vehicle control by assisted driving or the like using the fourth route information. Thus, the road information providing vehicle  30  may perform verification of the official map in the shadow mode. 
     Next, the road information providing vehicle  30  acquires road information from the road information acquisition unit  23  (S 302 ). Next, the road information providing vehicle  30  generates fifth route information from the road information acquired by the road information acquisition unit such as a camera (S 303 ). The fifth route information is information on an estimated route generated on the basis of the information acquired from the road information acquisition unit  23 . In this case, it does not matter whether the road information providing vehicle  30  performs vehicle control by assisted driving or the like using the fifth route information. Thus, the road information providing vehicle  30  may perform verification of the official map in the shadow mode. 
     Next, the road information providing vehicle  30  calculates a difference amount C between the fourth route information and the fifth route information (S 304 ). The calculated difference amount is stored in a storage unit (not shown). 
     Next, on the basis of route information generated from information acquired from the sensors such as the road information acquisition unit, the vehicle speed sensor, the satellite positioning system, and the inertia sensor, the road information providing vehicle  30  specifies and stores sixth route information which is information on a route on which the road information providing vehicle  30  actually travels (S 305 ). At S 305 , the sixth route information may be information on a route on which the road information providing vehicle  30  actually travels without being controlled by assisted driving or the like. 
     Next, the road information providing vehicle  30  calculates a difference amount D between the fourth route information and the sixth route information (S 306 ). The calculated difference amount is stored in the storage unit (not shown). 
     Next, the road information providing vehicle  30  determines quality of the official map from the difference amounts C and D (S 307 ). With regard to the quality of the official map, the difference amounts C and D exceeding a predetermined value mean that the quality is deteriorated, that is, the feature information or the like in the official map has changed after distribution of the official map and no longer matches the actual features. In this case, the quality of the official map is determined to be unacceptable. When the quality of the official map is unacceptable, the road information providing vehicle  30  transmits, to the server  10 , map coordinate data on a changed portion and feature change information which is information on a change in feature. 
     Thus, when the quality of the official map is evaluated to be unacceptable, map coordinate data on a changed portion and feature change information are transmitted from the plurality of road information providing vehicles  30  to the server  10 , and are sequentially accumulated in the server  10 . When a predetermined number of pieces of map coordinate data on a changed portion and feature change information are accumulated, as shown at S 102  in  FIG. 2 or 3 , the server  10  generates a temporary map. 
     The subsequent process follows the processing flow described in  FIGS. 2 to 4 . As shown in  FIG. 5 , when a portion at which a change in feature has occurred is present, during generation of a temporary map, the changed portion is provided with a flag QA=0 that means that the portion is unverified. When the quality of the temporary map is evaluated to be acceptable in the determination of the quality of the temporary map described above, QA=0 for the changed portion is changed to QA=1 that means that the portion is verified. 
     Thus, a cycle of generation of a temporary map→verification of the temporary map→update and distribution of an official map→verification of the official map→generation of a temporary map is appropriately performed, thereby maintaining freshness of the official map. 
     When the quality determination result of the temporary map at S 106  indicates that the quality of the temporary map is unacceptable, a determination result indicating that the quality determination result of the temporary map is unacceptable is transmitted to the server  10 , and the quality check result reflection unit  11   b  of the server  10  that has received the determination result does not transmit a signal for causing the temporary map to be an official map to the in-vehicle device  20 . In this case, the map generation unit  11   a  of the server  10  generates again a temporary map taking into consideration newly accumulated map coordinate data and feature change information, and through the processing flow shown in  FIG. 2 or 3 , the in-vehicle device  20  performs verification of the temporary map and determination of quality of the temporary map. 
     In verification of the official map by the road information providing vehicle  30 , when a driver, i.e., an occupant in the driver&#39;s seat operates the steering wheel, that is, when the occupant in the driver&#39;s seat intervenes in operation while steering operation or the like is being automatically controlled according to the road condition acquired by the sensors such as a camera and the first route information estimated on the basis of the distributed official map, the road information providing vehicle  30  may provide to the server  10  a report on a gap between the actual road condition and the official map data, associated with position information. In this case, the server  10  generates and distributes a new temporary map on the basis of the report from the road information providing vehicle  30 . 
     Even in the case where the first route information estimated from the official map data differs from the second route information estimated from the road condition acquired by the sensors such as a camera, when route information generated as a result of intervention by the occupant in the driver&#39;s seat in operation matches the first route information estimated on the basis of the distributed official map, it may be considered that the road condition acquired by the sensors such as a camera is erroneous and the official map is correct. 
     The process described above may be performed as follows. 
     When the verification vehicle that has received a temporary map verifies the temporary map and the verification result is good, the verification vehicle may use the temporary map for control of assisted driving, automatic driving, or the like without reporting the verification result to the server. The verification vehicle may report to the server only when the verification result of the temporary map is poor. Furthermore, the server may determine that the verification result of the temporary map is good on the basis of the fact that the server does not receive a poor verification result during a predetermined verification period. 
     A vehicle to which an official map is distributed specifies a detailed position of the own vehicle on the map on the basis of the verified official map and information acquired by the road information acquisition unit  23 , and performs automatic driving. Such vehicles include the verification vehicle including the in-vehicle device  20 , and the road information providing vehicle  30 . 
     The map generation system  1  according to the embodiments achieves the following effects. 
     The configuration of the map generation system  1  according to the embodiments performs verification of the temporary map by the in-vehicle device  20  of the verification vehicle and verification of the official map by the road information providing vehicle  30 ; thus, it is possible to provide a map generation system capable of providing map data with high reliability and maintaining highly fresh map data. 
     When the quality of the temporary map is acceptable, to a vehicle to which the temporary map has already been distributed, instead of transmitting updated official map data from the server  10  to the in-vehicle device  20 , the server  10  transmits a signal for updating the official data that has already been distributed to the in-vehicle device  20  to an official map. Thus, unnecessary data is not transmitted from the server  10  to the in-vehicle device  20 , leading to a reduction in the amount of data to be transmitted. This makes it possible for the in-vehicle device  20  to promptly acquire an official map. Furthermore, the amount of data communicated in the radio communication network  40  can be reduced; thus, for example, delay in communication in the entire radio communication network  40  can be avoided. 
     In the map generation system  1  according to the embodiments, determination of the quality of the temporary map by the in-vehicle device  20  of the vehicle that verifies the temporary map is performed in a mode in which no assisted driving or the like of the vehicle using the route information generated from the temporary map is performed. That is, verification of the temporary map is performed in the shadow mode. Accordingly, no assisted driving or the like using an unverified temporary map is performed; thus, a problem such as erroneous guidance of the vehicle can be avoided. 
     In the embodiments described above, the map data that is generated by the server and distributed to the vehicle may be a travel trajectory model. The travel trajectory model is, in other words, data indicating a travel trajectory that serves as a reference during automatic driving. The travel trajectory model may be obtained, for example, by averaging travel loci for the respective lanes. Through verification by the method described above, the travel trajectory model may also be generated as a temporary map or employed as an official map. Furthermore, an object to be verified in the distributed map may not necessarily be a tangible object such as a division line or a feature, and may be a virtual feature. The virtual feature indicates a virtual (intangible) object for controlling the vehicle. Such virtual features include the travel trajectory model described above, a virtual lane boundary line in an intersection, and the like. 
     The present disclosure has been described in accordance with the embodiments, but it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure encompasses various modifications and variations in an equivalent range. In addition, the scope and spirit of the present disclosure encompass various combinations or forms and other combinations or forms including only one element, one or more elements, or one or less elements. 
     CONCLUSION 
     As described, the present disclosure provides a method and system for generating a map and an in-vehicle device that are capable of providing map data with high reliability and maintaining highly fresh map data. 
     A first aspect of the present disclosure is a method executed by at least one processor in accordance with assisted driving or automatic driving of a vehicle. The method includes: acquiring road information from one or more sensors of the vehicle; acquiring a temporary map; calculating a difference amount A between route information generated from the temporary map and route information generated from the road information; and outputting a determination result indicating that quality of the temporary map is acceptable when the difference amount A is a predetermined value or less. 
     As a second aspect of the present disclosure, a map generation system is provided including: a server including a map generation unit and a quality check result reflection unit; and an in-vehicle device including an assisted driving control unit, a difference calculation unit, a map quality determination unit, and a road information acquisition unit. The map generation unit generates a temporary map and transmits the temporary map to the in-vehicle device. From first route information generated from the temporary map and second route information generated from road information acquired from the road information acquisition unit, the difference calculation unit calculates a difference amount A between the first route information and the second route information, and when the difference amount A is a predetermined value or less, a determination result indicating that quality of the temporary map is acceptable is transmitted to the quality check result reflection unit, and the quality check result reflection unit that has received the determination result transmits a signal for updating an official map using the temporary map to the in-vehicle device. 
     This configuration can provide a map generation system capable of providing map data with high reliability and maintaining highly fresh map data.