Control method and control system

Abstract

A vehicle system (1) switches control between a restart period from when the function of controlling travel of a vehicle is restarted after the elapse of a parking period in which the function has been stopped to when the vehicle moves and firstly detects a magnetic marker and a normal travel period after when the vehicle has detected the magnetic marker subsequent to the restart period. In the restart period, the vehicle system executes restart control (S105) for identifying the position of the vehicle on the basis of the position measured in the restart period and causing the vehicle to travel. In the normal travel period, the vehicle system executes normal travel control (S107) for identifying the position of the vehicle on the basis of the position of the detected magnetic marker and causing the vehicle to travel.

Description

[Technical Field]

[0001] The present invention relates to a control method and a control system for driving a vehicle using magnetic markers arranged on a road. [Background technology]

[0002] Conventionally, there has been known a system that uses lateral control to make a vehicle travel along a road by reducing the amount of lateral deviation of the vehicle relative to magnetic markers arranged on the road to nearly zero (see, for example, Patent Document 1). If a vehicle is equipped with a magnetic sensor for detecting the magnetic markers, as well as a millimeter-wave radar or lidar for detecting a preceding vehicle and measuring the distance between the vehicle using radio waves or reflected light, it can automatically travel along a road with magnetic markers, including following the preceding vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-334400 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the conventional system described above has a problem in that automatic driving is difficult during the period from when the vehicle starts moving until the magnetic marker can be detected for the first time, making manual driving unavoidable.

[0005] The present invention has been made in consideration of the above-mentioned conventional problems, and is an invention intended to provide a control method and control system for achieving a high level of autonomous driving through driving assistance control using magnetic markers. [Means for solving the problem]

[0006] One aspect of the present invention is a control method for a vehicle equipped with a magnetic sensor to travel on a road including a road on which magnetic markers that exert a magnetic field are arranged around the road, the method comprising: a restart period from when the function controlling the vehicle's driving is restarted after a parking period in which the function is stopped until the vehicle moves and first detects a magnetic marker; The control is switched between the restart period and the normal driving period after the vehicle detects the magnetic marker, During the restart period, the vehicle position is identified based on the position of the vehicle at the time of transition to the immediately preceding parking period or the position measured during the restart period, and control is executed to drive the vehicle, while In the normal driving period, the control method identifies the vehicle position based on the position of the detected magnetic marker and executes control to drive the vehicle.

[0007] One aspect of the present invention is a control system for a vehicle equipped with a magnetic sensor traveling on a road including a road on which magnetic markers that exert a magnetic field are arranged around the road, the control system comprising: a circuit for executing control of the vehicle to move by identifying the position of the vehicle based on the position of the vehicle at the time of transition to the immediately preceding parking period or the position measured during the restart period after the function for controlling the vehicle's movement is restarted after a parking period in which the function is stopped; and a circuit for executing control to identify the position of the vehicle based on the position of any of the detected magnetic markers during a normal running period after the restart period and when the vehicle first detects a magnetic marker; and and a circuit that executes control switching when the restart period transitions to the normal running period. [Effects of the Invention]

[0008] The present invention relates to a control method or control system for a vehicle traveling on a road provided with magnetic markers. In the control method and control system of the present invention, after a parking period in which a function for controlling the vehicle's traveling is stopped and then restarted, control is switched between a restart period from when the vehicle moves until it first detects a magnetic marker, and a normal traveling period after the vehicle detects the magnetic marker.

[0009] During the restart period, the vehicle position is identified based on the position of the vehicle at the time of transition to the immediately preceding parking period or the position measured during the restart period, and control is executed to run the vehicle. During the normal running period, the vehicle position is identified based on the position of the detected magnetic marker, and control is executed to run the vehicle.

[0010] In the control method and control system of the present invention, the restart period is set between the parking period and the normal driving period. Vehicle control during this restart period is control that does not require detection of a magnetic marker. By switching control between the normal driving period and the restart period, it is possible to drive the vehicle after the parking period until a magnetic marker can be detected. The control method and control system of the present invention can expand the range in which vehicle driving can be controlled, improving versatility.

[0011] In this way, the control method and control system of the present invention can realize a higher level of automated driving by utilizing magnetic markers arranged on the road. [Brief explanation of the drawings]

[0012] [Figure 1] An explanatory diagram of two areas accessible by highway. [Figure 2] A diagram of roads in the area. [Figure 3] FIG. [Figure 4] FIG. 1 is an explanatory diagram of a vehicle traveling on a road on which magnetic markers are provided. [Figure 5] Front view of an RFID tag. [Figure 6]FIG. [Figure 7] FIG. 1 is a block diagram showing the configuration of a vehicle system. [Figure 8] FIG. 1 is a flowchart showing the flow of basic processing. [Figure 9] FIG. 10 is a flowchart showing the flow of restart control. [Figure 10] FIG. 2 is an explanatory diagram showing a route to be controlled. [Figure 11] FIG. 4 is a flowchart showing the flow of normal driving control. [Figure 12] FIG. 2 is an explanatory diagram of a relative position estimated by inertial navigation. [Figure 13] An explanatory diagram of deviation ΔD from the route. [Figure 14] FIG. 10 is a flowchart showing another restart control flow. [Figure 15] FIG. 10 is a flowchart showing another restart control flow. DETAILED DESCRIPTION OF THE INVENTION

[0013] The embodiments of the present invention will be specifically described using the following examples. Example 1 This example is an example of a vehicle system 1 that is an example of a control system for a vehicle 5, and a control method for the vehicle 5. According to this control method and vehicle system 1, when traveling from home to work in the vehicle 5, it is possible to depart from the garage at home by automatic driving. This will be described with reference to Figs. 1 to 14.

[0014] This example illustrates a route traveled by a vehicle 5 between areas 60 connected by a main road 61. Within the area 60, travel is possible using community roads 62 (Fig. 2). Many of the main roads 61 are roads on which magnetic markers 10 are installed at intervals of, for example, 2 m. On the other hand, many of the community roads 62 are roads on which magnetic markers 10 are not installed. In this way, the roads on which the vehicle 5 travels include roads on which magnetic markers 10 are installed.

[0015] 2 is an example of an area 60, and shows the position of the vehicle 5 in the area 60. The figure also shows an area 60D as a departure point and an area 60A as a destination point. In the area 60D as a departure point, the reference numeral 622 represents, for example, the home, which is the departure point, and in the area 60A as a destination point, the reference numeral 622 represents, for example, the workplace, which is the destination point.

[0016] If the control targets include not only the main roads 61 on which magnetic markers 10 are installed but also the community roads 62 illustrated in Fig. 2, it is possible to automate the driving of a vehicle from an area 60D where a departure point is located to an area 60A where a destination point is located (see Fig. 1). For example, if a home 622 and a workplace are located in different areas 60, the vehicle 5 can depart from the home 622 in area 60D, travel to the area 60A where the workplace is located using the main roads 61, and then automatically travel the route to the workplace.

[0017] Below, the configurations of (1) the magnetic markers 10 and (2) the vehicle system 1 that are arranged on the track will be explained, and then (3) the operation of the vehicle system 1 will be explained. (1) Magnetic marker The magnetic marker 10 (Fig. 3) is a marker in which an RFID tag 15 (Radio Frequency Identification Tag, wireless tag) is integrated into a cylindrical magnet 10M with a diameter of 20 mm and a height of 28 mm. As shown in Fig. 4, the magnetic marker 10 is placed in a hole drilled in the road surface 100S. The magnet 10M constituting the magnetic marker 10 is a ferrite plastic magnet in which iron oxide magnetic powder, a magnetic material, is dispersed in a polymeric base material. Examples of polymeric materials include chlorinated polyethylene and polyphenylene sulfide (PPS).

[0018] In the magnetic marker 10, a sheet-like RFID tag 15 is disposed on the end face of a cylindrical magnet 10M. The RFID tag 15 is an electronic component that wirelessly outputs tag information. After disposing the RFID tag 15 on the end face of the magnet 10M, a coating layer made of a resin material may be provided on the surface. The coating layer may be a layer made of a composite material in which fibers are impregnated with a resin material. Alternatively, the RFID tag 15 may be disposed on the end face of the magnet 10M on which the coating layer has been formed. A coating layer may also be provided on all or part of the outer surface of the magnet 10M.

[0019] Furthermore, all or part of the RFID tag 15 may be embedded inside the magnet 10M. Instead of the columnar magnetic marker 10, a sheet-like magnetic marker made of a magnetic sheet may be used. In this case, the sheet-like RFID tag 15 may be laminated on the surface of the magnetic sheet. Furthermore, the magnetic marker may be made of two magnetic sheets bonded together. In this case, the sheet-like RFID tag 15 may be sandwiched between the two magnetic sheets.

[0020] The RFID tag 15 (FIG. 5) is an electronic component in which an IC chip 157 is mounted on the surface of a tag sheet 150 cut out from, for example, a PET (Polyethylene terephthalate) film. A printed pattern of an antenna 153 is provided on the surface of the tag sheet 150. The antenna 153 has both a power supply antenna function that generates an excitation current by external electromagnetic induction and a communication antenna function that wirelessly transmits information. The RFID tag 15 operates by external power supply via wireless communication, and externally outputs tag information such as a tag ID, which is identification information. The tag ID externally output by the RFID tag 15 is an example of the identification information of the magnetic marker 10.

[0021] As described above, the magnet 10M constituting the magnetic marker 10 is a magnet in which magnetic powder is dispersed in a polymer material. Such a magnet 10M has a large internal electrical resistance, so there is little risk of eddy currents being generated in response to wireless power supply to the RFID tag 15. Therefore, when this magnet 10M is used, power can be efficiently supplied to the RFID tag 15 from the outside. This magnet 10M is suitable as a magnet for holding the RFID tag 15.

[0022] (2) Vehicle Systems The vehicle system 1 (Figures 6 and 7) is composed of a control unit 18 that controls the driving of the vehicle 5, various driving control actuators that can be externally controlled, object detection sensors such as a millimeter wave radar 17 and an image sensor 19, a tag reader unit 14 that communicates with an RFID tag 15, and a positioning unit 16 that determines the absolute or relative position.

[0023] The control unit 18 is a circuit unit mainly configured around an electronic board (not shown) on which electronic components such as a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc. In the control unit 18, a storage device (storage medium) such as a hard disk drive (HDD) or a solid state drive (SSD), a wireless communication circuit, etc. are connected to the electronic board via I / O (Input / Output).

[0024] The control unit 18 utilizes the storage area of ​​the storage device to provide a marker database (marker DB) 18M that stores marker information about each magnetic marker 10, a map database (map DB) 18T that stores three-dimensional map data, etc. The three-dimensional map data represents the shape and structure of the road, as well as the three-dimensional structure of road accessories such as curbs, guardrails, medians, and signs, and the three-dimensional structure of the surrounding environment such as buildings and overpasses.

[0025] The marker information stored in the marker DB 18M is linked (associated) with a tag ID (tag information) that is identification information of the attached RFID tag 15. In the configuration of this example, the tag ID can be used to refer to the marker DB 18M, thereby identifying the corresponding magnetic marker 10.

[0026] The marker information includes location data (location information) indicating the installation location of the magnetic marker 10, information indicating the attributes of the installation location (road type, etc.), and regulatory information such as speed limits. As described above, this marker information is linked to a tag ID. The installation location of the magnetic marker 10 can be identified by referring to the marker DB 18M using the tag ID. In other words, the tag ID is an example of information that can identify the location of the magnetic marker 10.

[0027] The map data stored in the map DB 18T is composed of vector data that represents the road structure, surrounding environment, etc. This map data maps the installation position of each magnetic marker 10, etc. For example, if the vehicle 5 detects one of the magnetic markers 10, the vehicle's position in the map data can be identified by identifying that magnetic marker 10. Then, by identifying the vehicle's position in the map data, the shape and structure of the road ahead, as represented by the map data, can be ascertained.

[0028] The control unit 18 may be capable of receiving real-time traffic conditions, such as construction locations and traffic light status, from an external server at any time. In this case, a dynamic map reflecting real-time traffic conditions can be constructed, enabling vehicle control using the dynamic map.

[0029] The various actuators controlled by the control unit 18 include a throttle actuator 181 (FIG. 7) for adjusting engine output, a steering actuator 183 for changing the steering direction, a brake actuator 185 for adjusting braking force, etc. The control unit 18 can run the vehicle 5 by appropriately controlling these actuators.

[0030] The sensors connected to the control unit 18 include a magnetic sensor Cn, a millimeter-wave radar 17, an image sensor 19, etc. The magnetic sensor Cn is a sensor for detecting magnetism. The vehicle 5 incorporates a sensor array 21 in which 15 magnetic sensors Cn are arranged in a straight line. The sensor array 21 is a rod-shaped unit that is long in the vehicle width direction, and is attached to the bottom of the vehicle 5 in a state facing the road surface 100S.

[0031] The sensor array 21 includes a detection processing circuit 212 that performs detection processing and the like for the magnetic marker 10. The detection processing circuit 212 controls the 15 magnetic markers Cn to acquire magnetic measurement values ​​of each magnetic marker Cn. The detection processing circuit 212 then processes the magnetic measurement values ​​of each magnetic marker Cn to perform detection processing and the like for the magnetic marker 10.

[0032] In the sensor array 21 (FIG. 7), 15 magnetic sensors Cn are arranged at 10 cm intervals. The magnetic measurement values ​​output by the magnetic sensors C1 to C15 form a discrete magnetic distribution in the vehicle width direction. When the sensor array 21 (detection processing circuit 212) detects a magnetic marker 10, it outputs a detection signal indicating this and measures the amount of lateral deviation of the vehicle 5 relative to the magnetic marker 10. When the sensor array 21 is positioned directly above the magnetic marker 10, it can identify the position of the magnetic marker 10 in the vehicle width direction based on the distribution of magnetic measurement values ​​output by each magnetic sensor Cn (magnetic distribution in the vehicle width direction). Then, the sensor array 21 identifies the amount of lateral deviation of the vehicle relative to the magnetic marker 10 based on the position of the magnetic marker in the vehicle width direction.

[0033] The magnetic sensor Cn is preferably, for example, an MI sensor that detects magnetism using the well-known MI effect (Magneto Impedance Effect). The MI effect is a magnetic effect in which the impedance of a magnetically sensitive body, such as amorphous wire, changes sensitively in response to an external magnetic field. The MI sensor has magnetic sensitivity in the direction of the magnetically sensitive body that is linearly incorporated. The magnetic sensor Cn may be, for example, a magnetic sensor that can detect magnetic components in one direction, such as the vehicle width direction or the vertical direction. It may also be a magnetic sensor that can detect magnetic components in two directions, such as the magnetic component in the traveling direction and the magnetic component in the vehicle width direction. It may also be a magnetic sensor that can detect magnetic components in three directions, such as the magnetic component in the traveling direction, the vehicle width direction, and the vertical direction.

[0034] The millimeter-wave radar 17 is an object detection sensor that uses millimeter waves with a wavelength of 1 to 10 mm and a frequency of 30 to 300 GHz. The millimeter-wave radar 17 detects an object and measures the distance to the object by using the radio waves reflected when the millimeter waves are transmitted. The millimeter-wave radar 17 can detect people in addition to other vehicles and road structures such as guardrails and curbs. The millimeter-wave radars 17 are installed in the front, rear, left, and right corners of the vehicle body of the vehicle 5 so that the surroundings can be monitored.

[0035] The image sensor 19 is a sensor including a forward camera for capturing images of the environment ahead. The image sensor 19 is configured to include a processing circuit (not shown) that performs image processing. The image sensor 19 performs image processing on the captured image to detect lane markings, road signs, traffic lights, people, bicycles, preceding vehicles, oncoming vehicles, etc. When detecting pedestrians, etc., sensor fusion technology is utilized, which uses multiple sensors to improve detection accuracy, such as by performing image processing intensively on the gaze area identified by the millimeter wave sensor 17.

[0036] The positioning unit 16 includes a GPS (Global Positioning System) unit, an inertial measurement unit, and the like. The GPS unit is a unit that measures the vehicle position (vehicle location) using GPS, a type of GNSS (Global Navigation Satellite System). The inertial measurement unit is a unit that measures the rate of change of the vehicle's yaw angle (angular velocity) and the acceleration in the forward and lateral directions. The angular velocity and acceleration measured by the inertial measurement unit can be used to determine the relative position from a reference position (an example of the amount of displacement due to vehicle movement) and the direction of the vehicle. By using an inertial measurement unit, the relative position and turning angle (amount of change in yaw angle) after passing a reference position, such as the installation position of the magnetic marker 10, can be determined with high accuracy. By using an inertial measurement unit, it is possible to determine the vehicle's location in places such as tunnels where satellite radio waves cannot be received.

[0037] The tag reader unit 14 is a communication unit that wirelessly communicates with the RFID tag 15 held in the magnetic marker 10 (FIG. 4). The tag reader unit 14 wirelessly transmits the power required for the operation of the RFID tag 15 to operate the RFID tag 15 and reads the tag ID (tag information) that is the identification information of the RFID tag 15. Although the magnetic sensor array 21 and the tag reader unit 14 are shown as separate entities in FIG. 6, it is also possible to use an integrated unit.

[0038] (3) Vehicle system operation Next, the operation of the vehicle system 1 configured as described above will be described with reference to Figs. 8 to 13. Fig. 8 shows the flow of (3.1) basic processing when the vehicle 5 moves. Fig. 9 shows the flow of (3.2) restart control during the restart period following the parking period. Fig. 11 shows the flow of (3.3) normal driving control in which the vehicle drives while detecting the magnetic marker 10. Fig. 10 is a reference diagram used in the explanation of restart control. Figs. 12 and 13 are explanatory diagrams used in the explanation of normal driving control.

[0039] (3.1) Basic Processing The basic processing (FIG. 8) is the processing from switching on the ignition, which is the main power source of the vehicle 5 (IG ON), to switching off the ignition (IG OFF) upon arrival at the destination. The flow of this basic processing will be explained with reference to the flow diagram of FIG.

[0040] When the ignition of the vehicle 5 is switched to the on state after a parking period in which it is kept in the off state (IG on, S101: Yes), the control unit 18 acquires a destination point input by, for example, the user of the vehicle 5 (S102). Note that the destination point can be input using, for example, a mobile terminal (not shown) connected to the vehicle 5 so as to be able to communicate via a Bluetooth® function, or on a touch panel display (not shown) provided on the vehicle 5.

[0041] The control unit 18 refers to the 3D map data stored in the map DB 18T, calculates a route to the destination, and sets the route as a control target (S103). When determining the route to the destination, the control unit 18 also determines the magnetic marker 10 that the vehicle 5 will first reach using the restart control described below. The magnetic marker 10 determined by the control unit 18 in this way is the optimal magnetic marker that should be detected first when the vehicle reaches the destination. The control unit 19 also stores the identification information of the magnetic marker 10 determined when determining the route. As will be described in more detail later, the identification information of the magnetic marker 10 is information that serves as a trigger for switching from the restart control in step S105 to the normal driving control in step S107 described below.

[0042] Then, the control unit 18 reads out route data representing the route on the three-dimensional map data from the map DB 18T (S104), and starts control so that the vehicle 5 travels along the corresponding route.

[0043] The control unit 18 first executes restart control (described later with reference to FIG. 9) to cause the vehicle 5 to travel automatically based on the vehicle position determined by the positioning unit 16 (S105). This restart control is a control that does not require the presence of the magnetic marker 10, and is executed during the restart period until the magnetic marker 10 can be detected (S106: No → S105).

[0044] If the magnetic marker 10 determined when specifying the route to the destination as described above can be detected while the vehicle 5 is traveling under restart control (S106: Yes), that is, if a tag ID matching the identification information of the magnetic marker 10 stored by the control unit 18 as described above can be acquired from the corresponding RFID tag 15, the control unit 18 switches the control applied to the vehicle 5 from the restart control of step S105 to normal traveling control of step S107. The normal traveling control is control intended for roads on which magnetic markers 10 are installed, such as the trunk road 61. This normal traveling control is based on the premise that the magnetic markers 10 are continuously detected. The details of the normal traveling control will be described later with reference to FIGS. 11 to 13.

[0045] The control unit 18 executes normal driving control during the normal driving period from when the vehicle 5 starts moving from the departure point and first detects the magnetic marker 10 until the vehicle arrives at the destination point (S108: No → S107). When the vehicle arrives at the destination point, the control unit 18 ends the processing in response to switching the ignition of the vehicle 5 to the off state (IG OFF) (S109: Yes). When the IG is turned off, the control unit 18 stores (saves, memorizes, records) the vehicle position and the vehicle direction indicating the direction (absolute direction) of the vehicle 5 in a memory area.

[0046] For example, after entering a local road 62 (see FIG. 2) that branches off from a main road 61 (FIG. 2) and leads to a destination, it may become impossible to continuously detect the magnetic marker 10. In this case, the control unit 18 automatically drives the vehicle 5 using inertial navigation based on the last detected magnetic marker 10 (automatic driving control). This automatic driving control by the control unit 18 is executed as part of normal driving control, as will be described in more detail later.

[0047] (3.2) Restart control As described above, restart control (FIGS. 8 and 9) is control performed after the ignition of the vehicle 5 is switched on until the magnetic marker 10 can be detected. This restart control is control for causing the vehicle 5 to travel autonomously without relying on the magnetic marker 10. A situation in which restart control is applied is, for example, as shown in FIG. 10, when the vehicle 5 parked at home 622 starts to move, moves along arrow R1, and enters the main road 61 on which the magnetic marker 10 is installed. After entering the main road 61, control switches to normal travel control, which will be described in detail with reference to FIG. 11. Arrow R1 is part of the route to be controlled that was determined in step S103 in the basic processing described above.

[0048] 9, the control unit 18 first acquires positioning data from the positioning unit 16 (S201). The control unit 18 uses the positioning data to identify the vehicle position and vehicle orientation (S202). As described above, the positioning unit 16 includes a GPS unit that outputs position data representing an absolute position, an inertial measurement unit that outputs angular velocity and acceleration, and the like.

[0049] When the GPS unit is in a positioning capable state, the control unit 18 uses the position data from the GPS unit to identify the vehicle position on the route set in step S103. The control unit 18 also compares the three-dimensional structure of the surrounding area identified by the image sensor 19 and millimeter-wave radar 17 provided in the vehicle 5 with the three-dimensional structure of the area around the vehicle position represented by the three-dimensional map. Through this comparison, the control unit 18 increases the accuracy of the vehicle position and identifies the vehicle orientation, which indicates the direction of the vehicle 5.

[0050] If the vehicle 5 is traveling under restart control and GPS becomes unavailable, for example because satellite radio waves cannot be received, the control unit 18 determines the vehicle position and vehicle orientation using inertial navigation. The control unit 18 uses the most recent point in time at which the vehicle position and vehicle orientation were determined as a reference point and estimates the relative position of the vehicle 5 as it travels thereafter. The latest vehicle position is determined by adding the estimated relative position to the vehicle position at the reference point in time. The relative position of the vehicle 5 is determined based on the history of acceleration and angular velocity measured by the inertial measurement unit.

[0051] Furthermore, after the reference point in time, the control unit 18 estimates the turning angle using the measurement history of angular velocity by the inertial measurement unit. Specifically, the turning angle, which is the displacement of the yaw angle, can be calculated by integrating the angular velocity. The control unit 18 determines the latest vehicle orientation by adding the estimated turning angle (displacement of the yaw angle) to the vehicle orientation at the reference point in time. At this time, the accuracy of the vehicle position and vehicle orientation can be improved by grasping the three-dimensional structure of the surroundings using sensors such as the image sensor 19 and millimeter-wave radar 17 and comparing it with the three-dimensional structure represented by the three-dimensional map. Note that the vehicle position or vehicle orientation may be primarily estimated by comparing the three-dimensional structure of the surroundings grasped using the sensors with the three-dimensional structure represented by the three-dimensional map.

[0052] The control unit 18 identifies the position and orientation of the vehicle 5 on the route by combining the route data read out in step S104 with the vehicle position and vehicle orientation identified in step S202. As a result, the control unit 18 identifies the three-dimensional structure of the surroundings including the area ahead of the vehicle 5, and identifies the direction of the path of the vehicle 5 to travel along the route (S203).

[0053] The control unit 18 controls the vehicle 5 so that it travels in the direction of the path identified in step S203 (S204). During this control, the control unit 18 receives detection data from the millimeter-wave radar 17 and the image sensor 19 as needed, and controls the vehicle 5 while ensuring safety. For example, the millimeter-wave radar 17 can detect surrounding vehicles such as preceding vehicles and oncoming vehicles, guardrails, bicycles, pedestrians, etc. The image sensor 19 can detect road markings such as signs and crosswalks, and can also recognize the status of traffic lights.

[0054] As described above with reference to the flowchart of the basic processing in Figure 8, the restart control in Figure 9 continues until the magnetic marker 10 is detected (S106: No → S105 in Figure 8). When the magnetic marker 10 is detected, the restart control (Figure 9) is switched to the normal driving control (Figure 11) (S106: Yes → S107 in Figure 8).

[0055] (3.3) Normal driving control During the execution of the normal driving control of FIG. 11 , the control unit 18 switches the method of identifying the vehicle position, etc., depending on whether or not the magnetic marker 10 is detected (S301). If the magnetic marker 10 is detected (S301: detected), the control unit 18 acquires the tag ID (marker information) from the RFID tag 15 held in the magnetic marker 10 (S312). The control unit 18 uses the acquired tag ID to refer to the marker DB 18M and identifies the position (laying position) of the detected magnetic marker 10, etc. Then, the control unit 18 identifies the vehicle position based on the position of the detected magnetic marker 10 (S313). Specifically, the control unit 18 uses the laying position of the magnetic marker 10 as a reference and identifies the vehicle position as a position shifted by the amount of lateral deviation of the vehicle 5 from the magnetic marker 10.

[0056] On the other hand, when the vehicle 5 is located between adjacent magnetic markers 10 and the magnetic marker 10 cannot be detected (S301: no detection), the control unit 18 uses the vehicle position (position marked with a triangle in FIG. 12) identified based on the most recently detected installation position of the magnetic marker 10 as the reference position, and estimates the relative position of the vehicle 5 by inertial navigation (S302). Specifically, the control unit 18 estimates the relative position, etc., based on the angular velocity and acceleration measured by the inertial measurement unit. Then, as illustrated in FIG. 12, the control unit 18 identifies the position marked with an x, which is moved from the reference position by the amount of the relative position estimated in step S302, as the vehicle position (S313). Note that in the figure, an example of a vector representing this relative position is indicated by an arrow.

[0057] After identifying the vehicle position, the control unit 18 calculates a deviation ΔD of the vehicle position with reference to the control target route shown by the dashed line in Fig. 13. Then, the control unit 18 calculates the direction of the route based on this deviation ΔD (S314). The control unit 18 controls the vehicle 5 to travel in the direction of the route calculated in step S314 (S315). Note that, as in step S204 above, during execution of normal driving control, detection data and the like from the millimeter-wave radar 17 and the image sensor 19 are constantly input into the control unit 18, and the vehicle 5 is controlled while ensuring safety.

[0058] In addition, if the destination point is located in an area 60A (see FIG. 2) facing a community road 62 where no magnetic markers 10 are installed, automatic driving control using inertial navigation similar to the restart control in FIG. 9 may be required. In this case, the control unit 18 determines the vehicle position and vehicle orientation using inertial navigation in the flow of steps S301: No detection → S302 (S313). As a result, the control unit 18 determines the three-dimensional structure of the surroundings, including the area ahead of the vehicle 5, and determines the direction of travel for the vehicle 5 to travel along the route (S314).

[0059] Here, the difference in control between the main road 61 on which magnetic markers 10 are installed and roads on which magnetic markers 10 are not installed, such as community roads 62, is the presence or absence of lateral control, which brings the amount of lateral deviation of the vehicle 5 from the magnetic markers 10 closer to a predetermined value. On roads on which magnetic markers 10 are not installed, the control target for the steering angle is determined by referring to lane recognition using image processing or the like, the vehicle position measured by a GPS unit, and the vehicle orientation (yaw angle) based on measurements from an inertial measurement unit. On the other hand, on roads on which magnetic markers 10 are installed, in addition to the above, the control target for the steering angle is determined by using the amount of lateral deviation from the magnetic markers 10.

[0060] As described above, the control method of this example is a control method for a vehicle 5 equipped with a magnetic sensor Cn to travel on a road (track) on which magnetic markers 10 are installed. In this control method, after a parking period in which the function controlling the travel of the vehicle 5 is stopped and the function is restarted, control is switched between a restart period in which the vehicle 5 moves and detects the magnetic marker 10 for the first time, and a normal travel period after the magnetic marker 10 is detected.

[0061] During the restart period, restart control is executed to identify the vehicle position based on the position measured during the restart period following the parking period, and to drive the vehicle 5. During the normal driving period, normal driving control is executed to identify the vehicle position based on the position of the detected magnetic marker 10, and to drive the vehicle 5.

[0062] In the control of this example, a restart period in which restart control is applied is set between a parking period and a normal driving period. The control of the vehicle 5 during this restart period is control that does not assume the detection of the magnetic marker 10. By switching the control between the normal driving period and the restart period, automatic driving is possible from when the vehicle 5 starts moving after the parking period until it detects the magnetic marker 10. This control method can expand the area in which the driving of the vehicle 5 can be controlled, improving versatility. The control method of this example makes it possible to achieve a high level of automatic driving by using magnetic markers 10 arranged on the road.

[0063] In this example, when restart control is started in response to switching the IG on in step S101 (FIG. 8), step S201 (FIG. 9) is immediately executed. Alternatively, as shown in FIG. 14, immediately after restart control is started and before the vehicle position is identified (S210: YES), the positioning accuracy by the GPS may be evaluated (S211) to determine whether or not to identify the vehicle position based on the GPS positioning data.

[0064] Here, the accuracy of GPS positioning can be evaluated, for example, by using the number of satellites from which satellite signals can be received. For example, an evaluation can be performed by comparing the GPS positioning accuracy that can be expected based on the number of satellites from which satellite signals can be received with the estimated accuracy of the vehicle position stored in a memory area at the time of the most recent IG off, i.e., the transition to the immediately preceding parking period. For example, the size of the error circle can be used as an index of the accuracy of GPS positioning. For example, the range of error in the estimation of the vehicle position using inertial navigation can be used as an index of the accuracy of the vehicle position when the IG is off.

[0065] For example, if the size of the error circle obtained by GPS is smaller than the range of estimated error for the vehicle position when the ignition is off and the positioning accuracy by GPS is sufficient (S211: OK), the vehicle position may be determined based on the positioning data obtained by GPS (S212). That is, at the start of the restart period, the accuracy of the vehicle position determined by GPS is compared with the estimated accuracy of the vehicle position at the time of transition to the immediately preceding parking period, and if the positioning accuracy by GPS is higher, the vehicle position determined by GPS may be determined as the vehicle position at the start of the restart period. On the other hand, if the size of the error circle obtained by GPS is larger than the range of estimated error for the vehicle position when the ignition is off and the positioning accuracy by GPS is not sufficient (S211: NG), the vehicle position recorded when the ignition was off may be read (S222). That is, at the start of the restart period, the accuracy of the vehicle position measured by GPS is compared with the estimated accuracy of the vehicle position at the time of transition to the immediately preceding parking period, and if the estimated accuracy of the vehicle position at the time of transition to the immediately preceding parking period is higher, the estimated accuracy of the vehicle position at the time of transition to the immediately preceding parking period may be specified as the vehicle position at the start of the restart period. Note that the processing after the vehicle position is specified in step S212 or S222 is the same as the processing described with reference to FIG.

[0066] In this way, after switching the ignition on (corresponding to step S101: YES in FIG. 8), if the vehicle position is not yet determined (S210: YES), it is possible to determine whether the evaluation result of the GPS positioning accuracy is OK or NG (S211), and depending on the determination result, switch between determining the vehicle position based on the positioning data from the GPS unit (S212) and reading out the vehicle position when the ignition was off (S222). Naturally, in situations where GPS cannot be used because satellite radio waves cannot be received, such as in an underground parking lot, it is possible to determine NG in step S211 and read out the vehicle position when the ignition was off (S222).

[0067] In this example, a configuration is shown in which a sheet-like RFID tag 15 is attached to the top surface of the magnetic marker 10, but it is not essential that the magnetic marker 10 and the RFID tag 15 are integrated. It is sufficient that the magnetic marker 10 and the RFID tag 15 are arranged in the same position, and the RFID tag 15 may be arranged vertically above or below the magnetic marker 10.

[0068] It should be noted that the magnetic marker 10 in this example is a marker integrated with an RFID tag 15. Alternatively, magnetic markers without RFID tags 15 may be included. For example, RFID tags 15 may be provided on magnetic markers 10 located at intersections, while tagless magnetic markers may be placed in other locations. Alternatively, magnetic markers 10 with RFID tags 15 may be placed at intervals of every 5 locations, every 10 locations, etc., while tagless magnetic markers may be placed in other locations.

[0069] In this example, a main road 61 on which magnetic markers 10 are installed is illustrated, while a community road 62 for traveling within the area 60 is illustrated as having no magnetic markers 10. Alternatively, magnetic markers 10 may be installed on all roads. In this case, the restart period may be the period from when a vehicle departs from a parking lot facing the road until it enters the road and detects a magnetic marker for the first time, or the period from when a vehicle parked on the shoulder of the road resumes traveling until it detects a magnetic marker for the first time.

[0070] It is also possible to attach auxiliary magnetic markers to at least one of the magnetic markers 10. For example, the auxiliary magnetic markers may be positioned along the road direction, using the magnetic marker 10 as a reference. If the lateral deviation amount relative to the magnetic marker 10 and the lateral deviation amount relative to the auxiliary magnetic marker are known, the angle between the road direction, which is the direction connecting the magnetic marker 10 and the auxiliary magnetic marker, and the vehicle's traveling direction can be calculated, etc. The spacing between the magnetic marker 10 and the auxiliary magnetic marker is preferably a spacing that is expected to minimize changes in the steering amount of the vehicle. For example, a spacing of approximately 0.2 to 3.0 m, more preferably approximately 1.0 m, is preferable. The spacing may also be changed depending on the road's speed limit, as determined by law, etc. For example, a spacing of 1.5 to 3.0 m may be set on roads with high speed limits, and a spacing of 0.2 to 0.4 m may be set on roads with speed limits of approximately 10 to 20 km / h.

[0071] Example 2 This example is an example in which the restart control is modified based on the control method for vehicle 5 of the first embodiment. This modification will be described with reference to Fig. 15, which is a replacement diagram for Fig. 9 referred to in the description of the first embodiment. The restart control of this example replaces the restart control of the first embodiment, which mainly relies on GPS positioning, and mainly relies on autonomous navigation (dead reckoning) positioning.

[0072] The control unit (corresponding to reference numeral 18 in Fig. 6 and Fig. 7) in this example can take in the angular velocity (the rate of change of the yaw angle of the vehicle) output by the positioning unit (corresponding to reference numeral 16 in Fig. 6 and Fig. 7) as well as the vehicle speed pulse output in accordance with the rotation of the wheels. The control unit can perform positioning using autonomous navigation by using the angular velocity and vehicle speed pulse.

[0073] The restart control of this example (FIG. 15) is executed by the control unit in response to switching the ignition on (corresponding to step S101: YES in FIG. 8). When the restart control is started, the control unit first determines whether the vehicle position has not yet been determined, that is, whether the vehicle position is undetermined immediately after the start of the restart control (S320). If the vehicle position has not yet been determined (S320: YES), the control unit reads out the vehicle position and vehicle heading recorded the most recent time the ignition was turned off, that is, when the vehicle was parked (S321).

[0074] After the vehicle position is determined as described above (S320: NO), the control unit acquires the angular velocity, vehicle speed pulses, etc. from the positioning unit 16 (S322) and determines the vehicle position and vehicle direction by autonomous navigation (S202). Specifically, the control unit 18 estimates the relative position or relative direction of the vehicle 5 based on the angular velocity measurement history and the vehicle speed pulse output history after the most recent time point at which the vehicle position and vehicle direction were determined. The control unit then determines the latest vehicle direction by adding the estimated relative direction to the vehicle direction at a reference time point. Furthermore, the control unit determines, as the latest vehicle position, a position obtained by moving the estimated relative position along the latest vehicle direction using the vehicle position at the reference time point as a reference. Note that the processing after the vehicle position and vehicle direction are determined in step S202 above is the same as the processing described with reference to FIG. 9 in the first embodiment.

[0075] As a method of positioning using autonomous navigation, instead of or in addition to the method using angular velocity or vehicle speed pulses described above, a method of estimating the vehicle position and vehicle direction by detecting displacement from road surface images acquired continuously over time may be adopted. This method identifies the movement of patterns, etc. in road surface images taken at sufficiently short time intervals using an image technique such as pattern matching, and estimates the displacement of the vehicle based on the movement of the patterns, etc.

[0076] This method is similar to the motion detection method used in, for example, an optical mouse. With an optical mouse, only translational motion is detected, but rotational motion may also be detected in addition to translational motion. If rotational motion can be detected from a road surface image, which is a captured image of the road surface, it becomes possible to estimate the vehicle's orientation using autonomous navigation based on the road surface image. The road surface image may be, for example, an image of the road surface directly below the vehicle captured using an imaging camera mounted on the vehicle. For example, when capturing the road surface image, it is possible to irradiate light of a specific wavelength, such as infrared or laser light, while using a filter lens that transmits the specific wavelength when capturing the road surface image. For example, it is also possible to estimate the displacement of the vehicle based on the road surface image, while estimating the amount of change in the vehicle's orientation based on a forward image. The amount of change in the vehicle's orientation can be estimated by detecting lateral motion of, for example, a utility pole contained in forward images captured continuously over time. The forward image can be acquired using an imaging camera mounted on the vehicle so that it can capture the forward view.

[0077] The other configurations and effects are the same as those of the first embodiment.

[0078] Although specific examples of the present invention have been described in detail as examples, these examples merely disclose examples of the technology encompassed by the claims. Needless to say, the scope of the claims should not be interpreted as being limited by the configurations, numerical values, etc. of the specific examples. The claims encompass technologies that are obtained by variously modifying, changing, or appropriately combining the specific examples using publicly known technology and the knowledge of those skilled in the art. [Explanation of symbols]

[0079] 1 Vehicle System 10 Magnetic Markers 14 Tag reader unit 15 RFID tags (wireless tags) 16 Positioning Units 17 Millimeter wave radar 18 Control unit (circuit) 19 Image Sensor 18M marker database (marker DB, database) 18T Map Database (Map DB) 21 Sensor Array 212 Detection processing circuit 5 vehicles 60 Regions 61 Main Road 62 Community roads

Claims

1. A control method for a vehicle equipped with a magnetic sensor to travel on a road including a road on which magnetic markers that exert a magnetic field are arranged around the road, comprising: After a function for controlling the vehicle's driving is restarted after a parking period in which the function is stopped, control is switched between a restart period from when the vehicle moves until the magnetic marker is first detected, and a normal driving period from when the vehicle detects the magnetic marker after the restart period; When the parking period is entered in response to the stop of the function, the position of the vehicle at the time of the entry into the parking period is stored; At the start of the restart period, reading the vehicle position stored at the time of transition to the immediately preceding parking period; During the restart period, the vehicle position can be identified based on the vehicle position read at the start of the restart period, and control can be executed to run the vehicle. During the normal driving period, the control method identifies the vehicle's position based on the detected positions of the magnetic markers and controls the vehicle to drive.

2. A control method for a vehicle equipped with a magnetic sensor to travel on a road including a road on which magnetic markers that exert a magnetic field are arranged around the road, comprising: a restart period from when the function controlling the vehicle's driving is restarted after a parking period in which the function is stopped until the vehicle moves and first detects a magnetic marker; The control is switched between the restart period and the normal driving period after the vehicle detects the magnetic marker, During the restart period, the vehicle position is identified based on the position of the vehicle at the time of transition to the immediately preceding parking period or the position measured during the restart period, and control is executed to drive the vehicle, while During the normal driving period, a vehicle position is identified based on the detected positions of the magnetic markers, and control is executed to drive the vehicle; At the start of the restart period, a route to the destination is specified by calculation, a magnetic marker that should be detected first when the vehicle reaches the destination is determined, and identification information of the magnetic marker is stored; When a magnetic marker of the identification information stored at the start of the restart period is detected, the detection of the magnetic marker is used as a trigger to switch from the restart period to the normal running period; When the vehicle transitions to the parking period in response to the stop of the function of controlling the vehicle's running, information representing the positional accuracy of the vehicle position stored in response to the transition to the parking period is stored; A control method in which, at the start of the restart period, information representing the positional accuracy stored at the time of transition to the previous parking period is read, the positional accuracy represented by the read information is compared with the accuracy of the vehicle's position determined by a satellite positioning system, and the vehicle's position with the higher accuracy is identified as the vehicle's position at the start of the restart period.

3. 2. The method according to claim 1, wherein when the vehicle transitions to the parking period in response to the stop of the function for controlling the vehicle's running, information representing the positional accuracy of the vehicle position stored in response to the transition to the parking period is stored, A control method in which, at the start of the restart period, information representing the positional accuracy stored at the time of transition to the previous parking period is read, the positional accuracy represented by the read information is compared with the accuracy of the vehicle's position determined by a satellite positioning system, and the vehicle's position with the higher accuracy is identified as the vehicle's position at the start of the restart period.

4. A control method according to any one of claims 1 to 3, wherein during the restart period, a sensor mounted on the vehicle is used to grasp the three-dimensional structure of the surrounding area and the position of the vehicle is identified by comparing it with the three-dimensional structure represented by a three-dimensional map.

5. A control method according to any one of claims 1 to 4, which is capable of estimating the amount of displacement due to the vehicle's travel, and is capable of identifying the vehicle's position based on a reference position and an amount of displacement estimated for travel after passing the reference position.

6. 6. A control method according to claim 5, wherein the amount of displacement is estimated by capturing road surface images successively over time using an imaging camera mounted on a vehicle and comparing the road surface images captured at different times.

7. According to any one of claims 1 to 6, a database of position information indicating the installation positions of the magnetic markers is provided, A control method in which, when a vehicle detects any magnetic marker, the storage area of ​​the database is referenced to obtain the location information of the magnetic marker, and the vehicle's location is determined based on the location of the magnetic marker.

8. In any one of claims 1 to 7, a wireless tag is attached to any one of the magnetic markers, which wirelessly outputs information that can identify the installation position of any one of the magnetic markers, A control method for determining the vehicle's position based on the location of any of the magnetic markers, which is determined by the information output by the corresponding wireless tag when the vehicle detects any of the magnetic markers.

9. According to any one of claims 1 to 8, on the road on which the magnetic markers are arranged, an auxiliary magnetic marker for identifying the traveling direction of the vehicle is arranged adjacent to at least one of the magnetic markers, A control method for calculating the angle between the direction connecting the auxiliary magnetic marker and any one of the magnetic markers and the vehicle's direction of travel.

10. A control system for a vehicle equipped with a magnetic sensor to travel on a road including a road on which magnetic markers that exert a magnetic field are arranged around the road, a circuit for storing the position of the vehicle when the vehicle transitions to a parking period in which a function for controlling the vehicle's driving is stopped; a circuit for reading the vehicle position stored at the time of transition to a parking period when the function for controlling the vehicle's driving is restarted after the parking period in which the function is stopped; a circuit capable of executing control to identify the position of the vehicle based on the position of the vehicle read at the time of restarting the function and to run the vehicle during a restart period from when the function is restarted until the vehicle moves and first detects a magnetic marker; a circuit for executing control to identify the position of the vehicle based on the position of any of the detected magnetic markers during a normal running period after the restart period and when the vehicle first detects a magnetic marker; and a circuit that executes control switching when the restart period transitions to the normal running period.

11. A control system for a vehicle equipped with a magnetic sensor to travel on a road including a road on which magnetic markers that exert a magnetic field are arranged around the road, a circuit for executing control of the vehicle to move by identifying the position of the vehicle based on the position of the vehicle at the time of transition to the immediately preceding parking period or the position measured during the restart period after the function for controlling the vehicle's movement is restarted after a parking period in which the function is stopped; and a circuit for executing control to identify the position of the vehicle based on the position of any of the detected magnetic markers during a normal running period after the restart period and when the vehicle first detects a magnetic marker; and a circuit that executes control switching when the restart period transitions to the normal running period; a circuit for calculating a route to the destination when the function is restarted and determining a magnetic marker that should be detected first when the vehicle reaches the destination; a circuit for storing the determined identity of the magnetic marker upon restart of said function; a circuit for storing information indicating the positional accuracy of the vehicle position stored at the time of transition to the parking period in response to the stop of the function for controlling the vehicle's running; a circuit for reading, upon restart of said function, information representative of the positional accuracy stored at the time of transition to the previous parking period; a circuit for comparing the positional accuracy represented by the information read by the reading circuit with the accuracy of the vehicle position measured by a satellite positioning system, and specifying the vehicle position with higher accuracy as the vehicle position at the start of the restart period; The circuit that executes the control switching is configured to, when a magnetic marker with stored identification information is detected upon restarting the function, execute switching from the restart period to the normal driving period in response to the detection of the magnetic marker.

12. 11. The vehicle control system according to claim 10, further comprising: a circuit for storing information indicating the positional accuracy of the vehicle position stored at the time of transition to the parking period when the vehicle transitions to the parking period in response to the stop of the function for controlling the vehicle's running; a circuit for reading, upon restart of said function, information representative of the positional accuracy stored at the time of transition to the previous parking period; A control system comprising: a circuit that compares the positional accuracy represented by the information read by the reading circuit with the accuracy of the vehicle's position determined by a satellite positioning system, and identifies the vehicle's position with the higher accuracy as the vehicle's position at the start of the restart period.

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