Vehicle control method and position reliability calculation method

Abstract

To calculate reliability of position information of a vehicle.SOLUTION: The position information of the target vehicle is acquired based on a measurement result by a sensor mounted on the target vehicle, and includes a horizontal position and a vertical position of the target vehicle. A position reliability calculation method for calculating a reliability of position information of a target vehicle includes (A) acquiring an altitude of a representative point in a horizontal position of the target vehicle as a sensor-based altitude based on a vertical position included in the position information, (B) acquiring an altitude of the representative point in the horizontal position of the target vehicle as a map-based altitude based on an altitude map indicating a correspondence relationship among a latitude, a longitude, and an altitude of a road surface, and (C) calculating the reliability such that the reliability decreases as a deviation between the sensor-based altitude and the map-based altitude increases.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present disclosure relates to vehicle control using vehicle position information, and also to a technique for calculating the reliability of vehicle position information. [Background technology]

[0002] Patent Document 1 discloses a road surface displacement map that shows the correspondence between road surface displacement (road surface unevenness) and position. Vibration suppression control is performed by using such a road surface displacement map. Specifically, road surface displacement at a predetermined position ahead of the vehicle is recognized in advance from the road surface displacement map. A control amount for the active suspension is calculated in advance according to the recognized road surface displacement. Then, vehicle vibration is effectively suppressed by controlling the active suspension when the wheels pass the predetermined position. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2018 / 0154723 Summary of the Invention [Problem to be solved by the invention]

[0004] Consider vehicle control using vehicle position information. Generally, vehicle position information is acquired based on the measurement results of sensors mounted on the vehicle. If the accuracy of the vehicle position information is low, the accuracy of vehicle control using that position information may decrease. Therefore, when performing vehicle control using vehicle position information, it is preferable to understand how reliable that position information is. For this reason, it is desirable to calculate the reliability of the vehicle position information.

[0005] One object of the present disclosure is to provide a technology capable of calculating the reliability of vehicle position information.

[0006] Another object of the present disclosure is to provide a technology that can perform vehicle control using vehicle position information while taking into consideration the reliability of the vehicle position information. [Means for solving the problem]

[0007] The first aspect relates to a vehicle control method for controlling a target vehicle. The vehicle control method is acquiring position information including a horizontal position and a vertical position of the target vehicle based on measurement results by a sensor mounted on the target vehicle; Calculating the reliability of the location information; Taking into consideration the reliability of the location information, a location-based vehicle control is performed, which is a control of the target vehicle using the location information. Includes: Calculating the reliability of location information acquiring an altitude of a representative point in the horizontal position of the target vehicle as a sensor-based altitude based on the vertical position included in the position information; acquiring the altitude of a representative point in the horizontal position of the target vehicle as a map-based altitude based on an altitude map that indicates the correspondence relationship between the latitude, longitude, and altitude of the road surface; The reliability is calculated so that it becomes lower as the difference between the sensor-based altitude and the map-based altitude increases. Includes:

[0008] The second aspect relates to a position reliability calculation method for calculating the reliability of position information of a target vehicle by a computer. The position information is obtained based on measurements by sensors mounted on the target vehicle, and includes the horizontal and vertical positions of the target vehicle. The location reliability calculation method is as follows: acquiring an altitude of a representative point in the horizontal position of the target vehicle as a sensor-based altitude based on the vertical position included in the position information; acquiring the altitude of a representative point in the horizontal position of the target vehicle as a map-based altitude based on an altitude map that indicates the correspondence relationship between the latitude, longitude, and altitude of the road surface; The reliability is calculated so that it becomes lower as the difference between the sensor-based altitude and the map-based altitude increases. Includes: [Effects of the Invention]

[0009] According to the first aspect, it is possible to control the vehicle using the position information, taking into consideration the reliability of the position information of the vehicle.

[0010] According to the second aspect, it is possible to calculate the reliability of vehicle position information. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram illustrating an example of the configuration of a vehicle according to an embodiment. [Figure 2] 1 is a conceptual diagram illustrating a configuration example of a suspension according to an embodiment. [Figure 3] 4 is a flowchart illustrating an example of an unsprung displacement calculation process according to the embodiment. [Figure 4] 1 is a block diagram illustrating an example of the configuration of a vehicle control system according to an embodiment. [Figure 5] 3 is a block diagram showing an example of driving environment information according to an embodiment; [Figure 6] 1 is a block diagram illustrating an example of the configuration of a map management system according to an embodiment. [Figure 7] FIG. 4 is a conceptual diagram for explaining an unsprung displacement map according to the embodiment. [Figure 8] 10 is a flowchart showing an outline of a map generation / update process according to an embodiment. [Figure 9] FIG. 10 is a conceptual diagram for explaining preview control using an unsprung displacement map according to the embodiment. [Figure 10] 10 is a flowchart illustrating preview control using an unsprung displacement map according to an embodiment. [Figure 11] FIG. 10 is a conceptual diagram for explaining a method for calculating a position reliability according to an embodiment. [Figure 12] 10 is a flowchart illustrating a process related to location-based vehicle control according to an embodiment. [Figure 13] 10A and 10B are conceptual diagrams for explaining an example of preview control according to position reliability according to an embodiment. [Figure 14] 10A and 10B are conceptual diagrams for explaining another example of preview control according to position reliability according to the embodiment. [Figure 15] FIG. 10 is a conceptual diagram for explaining an example of automatic driving control according to position reliability according to an embodiment. [Figure 16] 10 is a flowchart showing a map generation / update process that takes into account position reliability according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0013] 1. Suspension and vertical movement parameters FIG. 1 is a schematic diagram showing an example configuration of a vehicle 1 according to this embodiment. The vehicle 1 is equipped with wheels 2 and suspensions 3. The wheels 2 include a left front wheel 2FL, a right front wheel 2FR, a left rear wheel 2RL, and a right rear wheel 2RR. Suspensions 3FL, 3FR, 3RL, and 3RR are provided for the left front wheel 2FL, the right front wheel 2FR, the left rear wheel 2RL, and the right rear wheel 2RR, respectively. In the following description, unless a distinction is particularly required, each wheel will be referred to as a wheel 2, and each suspension will be referred to as a suspension 3.

[0014] FIG. 2 is a conceptual diagram showing an example configuration of a suspension 3. The suspension 3 is provided to connect the unsprung structure 4 and the sprung structure 5 of the vehicle 1. The unsprung structure 4 includes the wheel 2. The suspension 3 includes a spring 3S, a damper (shock absorber) 3D, and an actuator 3A. The spring 3S, the damper 3D, and the actuator 3A are provided in parallel between the unsprung structure 4 and the sprung structure 5. The spring 3S has a spring constant K. The damping coefficient of the damper 3D is C. The damping force of the damper 3D may be variable. The actuator 3A applies a vertical control force Fc between the unsprung structure 4 and the sprung structure 5.

[0015] Here, the terms are defined. "Road surface displacement Zr" is the vertical displacement of the road surface RS. "Unsprung displacement Zu" is the vertical displacement of the unsprung structure 4. "Sprung displacement Zs" is the vertical displacement of the sprung structure 5. "Unsprung velocity Zu'" is the vertical velocity of the unsprung structure 4. "Sprung velocity Zs'" is the vertical velocity of the sprung structure 5. "Unsprung acceleration Zu''" is the vertical acceleration of the unsprung structure 4. "Sprung acceleration Zs''" is the vertical acceleration of the sprung structure 5. The sign of each parameter is positive when pointing upward and negative when pointing downward.

[0016] The wheel 2 moves on the road surface RS. In the following description, parameters related to the vertical motion of the wheel 2 are referred to as "vertical motion parameters." Examples of vertical motion parameters include the above-mentioned road surface displacement Zr, unsprung displacement Zu, unsprung velocity Zu', unsprung acceleration Zu'', sprung displacement Zs, sprung velocity Zs', and sprung acceleration Zs''. The vertical motion parameters can also be said to be "road surface displacement-related parameters" related to the road surface displacement Zr.

[0017] As an example, in the following description, a case where the vertical movement parameter is the unsprung displacement Zu will be considered. To generalize, the term "unsprung displacement" in the following description should be read as "vertical movement parameter."

[0018] FIG. 3 is a flowchart showing an example of the unsprung displacement calculation process.

[0019] In step S11, the sprung acceleration Zs'' is detected by the sprung acceleration sensor 22 installed in the sprung structure 5. In step S12, the sprung acceleration Zs'' is double-integrated to calculate the sprung displacement Zs.

[0020] In step S13, the stroke ST (= Zs - Zu), which is the relative displacement between the sprung structure 5 and the unsprung structure 4, is acquired. For example, the stroke ST is detected by a stroke sensor installed in the suspension 3. As another example, the stroke ST may be estimated based on the sprung acceleration Zs'' by an observer configured based on a single wheel two-degree-of-freedom model.

[0021] In step S14, filtering is performed on the time series data of the sprung displacement Zs to suppress the effects of sensor drift, etc. Similarly, in step S15, filtering is performed on the time series data of the stroke ST. For example, the filter is a band-pass filter that passes signal components in a specific frequency band. The specific frequency band may be set to include the sprung resonance frequency of the vehicle 1. For example, the specific frequency band is 0.3 to 10 Hz.

[0022] In step S16, the difference between the sprung displacement Zs and the stroke ST is calculated as the unsprung displacement Zu.

[0023] Instead of steps S14 and S15, a filtering process may be performed on the time series data of the unsprung displacement Zu calculated in step S16.

[0024] As yet another example, the unsprung acceleration Zu'' may be detected by an unsprung acceleration sensor, and the unsprung displacement Zu may be calculated from the unsprung acceleration Zu''.

[0025] 2. Vehicle Control System 2-1.Configuration example 4 is a block diagram showing an example of the configuration of a vehicle control system 10 according to this embodiment. The vehicle control system 10 is applied to a vehicle 1 and controls the vehicle 1. For example, the vehicle control system 10 is mounted on the vehicle 1. As another example, the vehicle control system 10 may be distributed between the vehicle 1 and a remote device. The vehicle control system 10 includes a vehicle state sensor 20, a recognition sensor 30, a position sensor 40, a communication device 50, a driving device 60, and a control device 70.

[0026] The vehicle state sensor 20 is mounted on the vehicle 1 and detects the state of the vehicle 1. The vehicle state sensor 20 includes a vehicle speed sensor (wheel speed sensor) 21 that detects the vehicle speed V of the vehicle 1, a sprung acceleration sensor 22 that detects the sprung acceleration Zs'', and the like. The vehicle state sensor 20 may also include a stroke sensor 23 that detects the stroke ST. The vehicle state sensor 20 may also include an unsprung acceleration sensor. In addition, the vehicle state sensor 20 includes a lateral acceleration sensor, a yaw rate sensor, a steering angle sensor, and the like.

[0027] The recognition sensor 30 is mounted on the vehicle 1 and recognizes (detects) the situation around the vehicle 1. Examples of the recognition sensor include a camera, a LIDAR (Laser Imaging Detection and Ranging), and a radar.

[0028] The position sensor 40 is mounted on the vehicle 1 and includes a positioning device that detects the position and orientation of the vehicle 1. For example, the position sensor 40 includes a Global Navigation Satellite System (GNSS). For example, the position sensor 40 includes an RTK-GNSS.

[0029] The communication device 50 communicates with the outside of the vehicle 1 .

[0030] The traveling device 60 includes a steering device 61, a drive device 62, a braking device 63, and a suspension 3 (see FIG. 2) mounted on the vehicle 1. The steering device 61 steers the wheels 2. For example, the steering device 61 includes an electric power steering (EPS) device. The drive device 62 is a power source that generates a driving force. Examples of the drive device 62 include an engine, an electric motor, and an in-wheel motor. The braking device 63 generates a braking force.

[0031] The control device 70 is a computer that controls the vehicle 1. The control device 70 may be mounted on the vehicle 1, or may be partially included in a remote device. The control device 70 includes one or more processors 71 (hereinafter simply referred to as processor 71) and one or more storage devices 72 (hereinafter simply referred to as storage devices 72). The processor 71 executes various processes. For example, the processor 71 includes a CPU (Central Processing Unit). The processor 71 can also be called a processing circuitry. The storage device 72 stores various information required for processing by the processor 71. Examples of the storage device 72 include a volatile memory, a non-volatile memory, an HDD (Hard Disk Drive), an SSD (Solid State Drive), etc. The control device 70 may include one or more ECUs (Electronic Control Units).

[0032] The vehicle control program 80 is a computer program for controlling the vehicle 1, and is executed by the processor 71. The vehicle control program 80 is stored in the storage device 72. Alternatively, the vehicle control program 80 may be recorded on a computer-readable recording medium. The processor 71 executes the vehicle control program 80, thereby realizing the functions of the control device 70.

[0033] 2-2. Driving environment information 5 is a block diagram showing an example of driving environment information 90 that indicates the driving environment of the vehicle 1. The driving environment information 90 is stored in the storage device 72. The driving environment information 90 includes map information 91, vehicle state information 92, surrounding situation information 93, and location information 94.

[0034] The map information 91 includes a general navigation map. The map information 91 may indicate lane layout, road shape, etc. The map information 91 may also include position information of white lines, traffic lights, signs, landmarks, etc. The map information 91 is obtained from a map database. The map database may be installed in the vehicle 1 or may be stored in an external management server. In the latter case, the control device 70 communicates with the management server to obtain the necessary map information 91.

[0035] The map information 91 further includes an "unsprung displacement map 200." The unsprung displacement map 200 will be described in detail later.

[0036] The vehicle state information 92 is information that indicates the state of the vehicle 1. The control device 70 acquires the vehicle state information 92 from the vehicle state sensor 20. For example, the vehicle state information 92 includes the vehicle speed V, the sprung acceleration Zs'', the stroke ST, the lateral acceleration, the yaw rate, the steering angle, and the like. The vehicle speed V may be calculated from the vehicle position detected by the position sensor 40. The control device 70 may calculate the unsprung displacement Zu by the method shown in FIG. 3. In this case, the vehicle state information 92 also includes the unsprung displacement Zu calculated by the control device 70.

[0037] The surrounding situation information 93 is information that indicates the situation around the vehicle 1. The control device 70 recognizes the situation around the vehicle 1 using the recognition sensor 30 and acquires the surrounding situation information 93. For example, the surrounding situation information 93 includes image information captured by a camera. As another example, the surrounding situation information 93 includes point cloud information obtained by LIDAR.

[0038] The surrounding situation information 93 further includes "object information" relating to objects around the vehicle 1. Examples of objects include pedestrians, bicycles, other vehicles (preceding vehicles, parked vehicles, etc.), road configurations (white lines, curbs, guardrails, walls, medians, roadside structures, etc.), signs, poles, obstacles, etc. The object information indicates the relative position and relative speed of the object with respect to the vehicle 1. For example, by analyzing image information obtained by a camera, it is possible to identify the object and calculate the relative position of the object. It is also possible to identify the object and obtain the relative position and relative speed of the object based on point cloud information obtained by LIDAR.

[0039] The position information 94 is information indicating the position and orientation of the vehicle 1. The position includes a horizontal position and a vertical position. For example, the horizontal position is defined by latitude and longitude. The vertical position is defined by altitude (elevation). Examples of altitude include sea level, geoid height, and ellipsoid height. The control device 70 acquires the position information 94 based on the measurement results of a position sensor 40 such as a GNSS. As another example, the control device 70 may acquire the position information 94 by dead reckoning. As yet another example, the control device 70 may acquire highly accurate position information 94 by a well-known self-position estimation process (localization) that uses object information and map information 91.

[0040] 2-3.Vehicle control The control device 70 performs vehicle driving control to control the driving of the vehicle 1. The vehicle driving control includes steering control, drive control, and braking control. The control device 70 performs vehicle driving control by controlling the driving devices 60 (steering device 61, drive device 62, and braking device 63). The control device 70 may perform driving assistance control to assist the driving of the vehicle 1 based on the driving environment information 90. Examples of driving assistance control include lane keeping control, collision avoidance control, and automatic driving control.

[0041] Furthermore, the control device 70 controls the suspension 3. Typically, the control device 70 controls the suspension 3 to perform vibration suppression control that suppresses vibration of the vehicle 1. For example, the control device 70 controls the actuator 3A to generate a control force Fc in the vertical direction between the unsprung structure 4 and the sprung structure 5 (see FIG. 2). As another example, the control device 70 may variably control the damping force of the damper 3D. The vibration suppression control includes a "preview control" that will be described later.

[0042] 3. Map Management System 3-1.Configuration example 6 is a block diagram showing an example of the configuration of a map management system 100 according to this embodiment. The map management system 100 is a computer that manages various types of map information. The management of map information includes the generation, updating, provision, distribution, etc. of the map information. Typically, the map management system 100 is a management server on a cloud. The map management system 100 may be a distributed system in which multiple servers perform distributed processing.

[0043] The map management system 100 includes a communication device 110. The communication device 110 is connected to a communication network NET. For example, the communication device 110 communicates with a large number of vehicles 1 via the communication network NET.

[0044] The map management system 100 further includes one or more processors 120 (hereinafter simply referred to as processors 120) and one or more storage devices 130 (hereinafter simply referred to as storage devices 130). The processor 120 executes various types of information processing. For example, the processor 120 includes a CPU. The processor 120 can also be called a processing circuitry. The storage device 130 stores various types of map information. The storage device 130 also stores various types of information required for processing by the processor 120. Examples of the storage device 130 include volatile memory, non-volatile memory, HDD, SSD, etc.

[0045] The map management program 140 is a computer program for map management, and is executed by the processor 120. The map management program 140 is stored in the storage device 130. Alternatively, the map management program 140 may be recorded on a computer-readable recording medium. The processor 120 executes the map management program 140 to implement the functions of the map management system 100.

[0046] The processor 120 communicates with the vehicle control system 10 of the vehicle 1 via the communication device 110. The processor 120 collects various information from the vehicle control system 10, and generates and updates map information based on the collected information. The processor 120 also distributes the map information to the vehicle control system 10. The processor 120 also provides the map information in response to a request from the vehicle control system 10.

[0047] 3-2.Unsprung displacement map One of the pieces of map information managed by the map management system 100 is the "unsprung displacement map (vertical movement parameter map) 200." The unsprung displacement map 200 is a map relating to unsprung displacement Zu (vertical movement parameter) and indicates the correspondence between unsprung displacement Zu (vertical movement parameter) and position. The unsprung displacement map 200 is stored in the storage device 130.

[0048] FIG. 7 is a conceptual diagram for explaining the unsprung displacement map 200. The XY plane represents a horizontal plane. For example, the absolute coordinate system on the horizontal plane is defined by the latitude and longitude directions, and the horizontal position is defined by the latitude and longitude. The unsprung displacement map 200 represents the correspondence between at least the horizontal position (X, Y) and the unsprung displacement Zu. In other words, the unsprung displacement map 200 represents the unsprung displacement Zu as a function of at least the horizontal position (X, Y).

[0049] The road area may be divided into a mesh pattern on a horizontal plane. That is, the road area may be divided into a plurality of unit areas M on a horizontal plane. The unit area M is, for example, a square. The length of one side of the square is, for example, 10 cm. The unsprung displacement map 200 represents the correspondence between the position of the unit area M and the unsprung displacement Zu. The position of the unit area M may be defined by a representative position of the unit area M (e.g., a central position), or may be defined by the range of the unit area M (latitude range, longitude range). The unsprung displacement Zu of the unit area M is, for example, the average value of the unsprung displacement Zu acquired within the unit area M. The smaller the unit area M is, the higher the resolution of the unsprung displacement map 200.

[0050] 3-3. Map generation / update processing The processor 120 collects information from a large number of vehicles 1 via the communication device 110. Then, the processor 120 generates and updates the unsprung displacement map 200 based on the information collected from the large number of vehicles 1. An example of the map generation / update process will be described in more detail below.

[0051] The positions in the unsprung displacement map 200 are positions that the wheels 2 have passed through. The position of each wheel 2 is calculated based on the above-mentioned position information 94. Specifically, the relative positional relationship between the reference point of the vehicle position on the vehicle 1 and each wheel 2 is known information. Based on this relative positional relationship and the vehicle position indicated by the position information 94, the position of each wheel 2 can be calculated.

[0052] The unsprung displacement Zu is calculated by the method shown in Fig. 3. That is, the sprung displacement Zs and the stroke ST are obtained by using the vehicle state sensor 20 mounted on the vehicle 1. For convenience, the sprung displacement Zs and the stroke ST are referred to as "sensor-based information." The unsprung displacement Zu is calculated based on this sensor-based information.

[0053] For example, while the vehicle 1 is traveling, the control device 70 of the vehicle control system 10 calculates the unsprung displacement Zu in real time based on sensor-based information. The control device 70 also associates the wheel position and the unsprung displacement Zu at the same timing. The control device 70 then transmits a set of time-series data of the wheel position and time-series data of the unsprung displacement Zu to the map management system 100. The processor 120 of the map management system 100 generates and updates the unsprung displacement map 200 based on the time-series data of the wheel position and the time-series data of the unsprung displacement Zu.

[0054] As another example, the control device 70 of the vehicle control system 10 associates wheel positions with sensor-based information at the same time. Then, the control device 70 transmits a set of time-series data of the wheel positions and time-series data of the sensor-based information to the map management system 100. The processor 120 of the map management system 100 calculates the unsprung displacement Zu based on the received sensor-based information. Furthermore, the processor 120 generates and updates the unsprung displacement map 200 based on the time-series data of the wheel positions and the time-series data of the unsprung displacement Zu.

[0055] When calculating the unsprung displacement Zu in the map management system 100, there is no restriction on processing time, so filtering processing can be performed using a zero-phase filter. By using a zero-phase filter, it is possible to prevent "phase shift."

[0056] FIG. 8 is a flowchart showing an outline of the map generation / update process according to this embodiment.

[0057] In step S100, the processor 120 of the map management system 100 acquires "map update information" from the vehicle 1 (vehicle control system 10) via the communication device 110. The map update information includes time series data of the position (wheel position) of the vehicle 1. The map update information also includes time series data of sensor-based information (e.g., sprung displacement Zs, stroke ST) required to calculate the unsprung displacement Zu. Alternatively, the map update information may include time series data of the unsprung displacement Zu calculated by the control device 70 of the vehicle control system 10.

[0058] In step S200, the processor 120 of the map management system 100 generates / updates the unsprung displacement map 200 based on the map update information.

[0059] 3-4. Modifications The vehicle control system 10 of the vehicle 1 may hold a database of the unsprung displacement map 200 and generate / update its own unsprung displacement map 200. In other words, the map management system 100 may be included in the vehicle control system 10.

[0060] 4. Preview control using unsprung displacement map The control device 70 of the vehicle control system 10 communicates with the map management system 100 via the communication device 50. The control device 70 acquires an unsprung displacement map 200 of an area including the current position of the vehicle 1 from the map management system 100. The unsprung displacement map 200 is stored in the storage device 72. Then, the control device 70 executes "preview control," which is a type of vibration suppression control, based on the unsprung displacement map 200.

[0061] Fig. 9 is a conceptual diagram for explaining preview control, and Fig. 10 is a flowchart showing preview control. Preview control will be described with reference to Figs.

[0062] In step S31, the control device 70 acquires the current position P0 of each wheel 2. The relative positional relationship between the reference point of the vehicle position on the vehicle 1 and each wheel 2 is known information. Based on this relative positional relationship and the vehicle position indicated by the position information 94, the position of each wheel 2 can be calculated.

[0063] In step S32, the control device 70 calculates a predicted passing position Pf of the wheel 2 after the preview time tp. The preview time tp is set, for example, to be equal to or longer than the time required for calculation processing and communication processing required to operate the actuator 3A of the suspension 3. The preview time tp may be fixed or may be variable depending on the situation. The preview distance Lp is given by the product of the preview time tp and the vehicle speed V. The predicted passing position Pf is a position that is the preview distance Lp ahead of the current position P0. As a modified example, the control device 70 may calculate a predicted traveling route based on the vehicle speed V and the steering angle of the wheel 2, and calculate the predicted passing position Pf based on the predicted traveling route.

[0064] In step S33, the control device 70 reads out the unsprung displacement Zu at the predicted passing position Pf from the unsprung displacement map 200.

[0065] In step S34, the control device 70 calculates, based on the unsprung displacement Zu at the predicted passing position Pf, a target control force Fc_t of the actuator 3A of the suspension 3. The target control force Fc_t is calculated, for example, as follows.

[0066] The equation of motion for the sprung structure 5 (see FIG. 2) is expressed by the following equation (1).

[0067]

number

[0068] In equation (1), m is the mass of the sprung structure 5, C is the damping coefficient of the damper 3D, K is the spring constant of the spring 3S, and Fc is the vertical control force Fc generated by the actuator 3A. If the vibration of the sprung structure 5 is completely canceled out by the control force Fc (Zs''=0, Zs'=0, Zs=0), the control force Fc is expressed by the following equation (2).

[0069]

number

[0070] The control force Fc that provides at least a vibration damping effect is expressed by the following equation (3).

[0071]

number

[0072] In equation (3), gain α is greater than 0 and less than or equal to 1, and gain β is also greater than 0 and less than or equal to 1. When the differential term in equation (3) is omitted, the control force Fc that provides at least the vibration damping effect is expressed by the following equation (4).

[0073]

number

[0074] The control device 70 calculates the target control force Fc_t according to the above formula (3) or formula (4). That is, the control device 70 calculates the target control force Fc_t by substituting the unsprung displacement Zu at the predicted passing position Pf into formula (3) or formula (4).

[0075] In step S35, the control device 70 controls the actuator 3A to generate a target control force Fc_t at the timing when the wheel 2 passes through the predicted passing position Pf. The timing when the wheel 2 passes through the predicted passing position Pf can be determined from the preview time tp.

[0076] The preview control using the unsprung displacement map 200 described above makes it possible to effectively suppress vibrations of the vehicle 1 (sprung structure 5).

[0077] 5. Location reliability In the following description, for convenience, the target of control by the vehicle control system 10 (control device 70) will be referred to as the "target vehicle 1T." Furthermore, vehicle control using the position information 94 of the target vehicle 1T will be referred to as the "position-based vehicle control." The above-described preview control that uses the position information 94 to calculate the position of the wheel 2 is an example of position-based vehicle control.

[0078] If the accuracy of the position information 94 of the target vehicle 1T is low, the accuracy of position-based vehicle control may decrease. Therefore, when performing position-based vehicle control, it is preferable to understand (recognize) how reliable the position information 94 of the target vehicle 1T is. For this purpose, it is desirable to calculate the reliability of the position information 94 of the target vehicle 1T. The reliability of the position information 94 of the target vehicle 1T will be referred to as "position reliability R" hereinafter.

[0079] If the position reliability R of the position information 94 can be grasped, it is possible to appropriately adjust the content of the position-based vehicle control according to the position reliability R. For example, if the position reliability R is low, it is possible to suppress the position-based vehicle control. However, if the accuracy (reliability) of the position reliability R itself is low, the accuracy of the position-based vehicle control may ultimately decrease, or the effectiveness of the position-based vehicle control may decrease. For example, if the position reliability R is erroneously determined to be high when it is actually low, the accuracy of the position-based vehicle control may decrease. Conversely, if the position reliability R is erroneously determined to be low when it is actually high, the position-based vehicle control may be unnecessarily suppressed, and the effect of the position-based vehicle control may not be fully achieved. Therefore, it is desirable to also increase the calculation accuracy (reliability) of the position reliability R itself.

[0080] FIG. 11 is a conceptual diagram for explaining a method for calculating the position reliability R according to this embodiment.

[0081] As described above, the position information 94 of the target vehicle 1T is obtained based on the measurement results by the position sensor 40 mounted on the target vehicle 1T. The position information 94 includes the horizontal position and vertical position of the target vehicle 1T. For example, the horizontal position is defined by latitude and longitude. The vertical position is defined by altitude (elevation). Examples of altitude include sea level, geoid height, and ellipsoid height.

[0082] The horizontal and vertical positions of the target vehicle 1T more precisely refer to the horizontal and vertical positions of a "vehicle reference point" that moves along with the target vehicle 1T. The vehicle reference point of the target vehicle 1T is arbitrary. For example, the vehicle reference point of the target vehicle 1T may be the center point of the target vehicle 1T or the mounting position of the position sensor 40. The design value (default value) of the relative height of the vehicle reference point from the road surface is given as known information. Furthermore, the relative height of the vehicle reference point from the road surface may be corrected from the design value, taking into account the stroke ST of the suspension 3, the inclination of the vehicle body (roll angle, pitch angle), tire deflection, etc. In either case, the relative height of the vehicle reference point from the road surface is obtained. The control device 70 can convert the vertical position of the target vehicle 1T to the altitude of the road surface based on the relative height of the vehicle reference point from the road surface. Similarly, the control device 70 can convert the altitude of the road surface to the vertical position of the target vehicle 1T based on the relative height of the vehicle reference point from the road surface.

[0083] The control device 70 of the vehicle control system 10 acquires the altitude of the "representative point P" in the horizontal position of the target vehicle 1T. For example, the representative point P is the road surface. As another example, the representative point P may be a point that is a certain height away from the road surface. As yet another example, the representative point P may be the vehicle reference point of the target vehicle 1T. As described above, the altitude of the road surface and the vertical position of the vehicle reference point can be converted into each other. Therefore, if the altitude of the road surface or the vertical position of the vehicle reference point is known, the altitude of the representative point P can be calculated.

[0084] According to this embodiment, the control device 70 acquires the altitude of the representative point P in the horizontal position of the target vehicle 1T by two different methods.

[0085] The first method uses position information 94 of the target vehicle 1T. The control device 70 acquires the altitude of the representative point P in the horizontal position of the target vehicle 1T based on the vertical position of the target vehicle 1T (vehicle reference point) included in the position information 94. As described above, if the vertical position of the vehicle reference point is known, the altitude of the representative point P can be calculated. The altitude of the representative point P acquired based on the position information 94 in this way will hereinafter be referred to as the "sensor-based altitude Hsen."

[0086] The second method uses an altitude map 400 that indicates the correspondence between the latitude, longitude, and altitude of the road surface (ground). Examples of altitude include sea level, geoidal height, and ellipsoidal height. For example, map data published by the Geospatial Information Authority of Japan may be used as the altitude map 400. The altitude map 400 is a type of map information 91, and is pre-stored in the storage device 72. The control device 70 reads out the altitude of the road surface at the horizontal position of the target vehicle 1T from the altitude map 400. Furthermore, the control device 70 calculates the altitude of the representative point P based on the altitude of the road surface read out from the altitude map 400. The altitude of the representative point P obtained in this way based on the altitude map 400 will hereinafter be referred to as the "map-based altitude Hmap."

[0087] Next, the control device 70 calculates the altitude deviation ΔH (=|Hsen-Hmap|) between the sensor-based altitude Hsen and the map-based altitude Hmap for the representative point P at the same horizontal position. Then, the control device 70 calculates the position reliability R of the position information 94 based on the altitude deviation ΔH. The smaller the altitude deviation ΔH, the higher the position reliability R. Conversely, the larger the altitude deviation ΔH, the lower the position reliability R.

[0088] As described above, according to this embodiment, it is possible to calculate the position reliability R of the position information 94 of the target vehicle 1T. In particular, by referring to the altitude map 400, which is the correct data, it is possible to calculate the position reliability R of the position information 94 with high accuracy.

[0089] As a comparative example, a location estimation algorithm such as a GNSS may estimate and output the reliability of its own location estimation process. However, the reliability of such a location estimation process is estimated solely based on internal parameters of the location estimation process, not on the correct data. The accuracy of the reliability estimated by the location estimation algorithm is lower than the accuracy of the location reliability R obtained by referencing the altitude map 400, which is the correct data.

[0090] 6. Position-based vehicle control considering position reliability 12 is a flowchart showing the processing related to location-based vehicle control according to this embodiment. In step S40, the control device 70 of the vehicle control system 10 acquires location information 94 of the target vehicle 1T. In step S50, the control device 70 calculates the location reliability R of the location information 94. The method of calculating the location reliability R is as described in Section 5 above.

[0091] In step S60, the control device 70 executes the position-based vehicle control in consideration of the position reliability R. More specifically, the control device 70 flexibly adjusts the "degree" of the position-based vehicle control according to the position reliability R. The degree of the position-based vehicle control is expressed, for example, by the gain of the position-based vehicle control. The higher the gain of the position-based vehicle control, the higher the degree of the position-based vehicle control.

[0092] For example, the control device 70 may decrease the degree of position-based vehicle control as the position reliability R decreases. Conversely, the control device 70 may increase the degree of position-based vehicle control as the position reliability R increases. This can be generalized as follows. Consider a first position reliability R1 and a second position reliability R2 that is lower than the first position reliability R1 (R1>R2) as the position reliability R. The control device 70 decreases the degree of position-based vehicle control for the second position reliability R2 compared to the degree of position-based vehicle control for the first position reliability R1. This makes it possible to prevent inappropriate position-based vehicle control from being performed when the position reliability R is low. Furthermore, it becomes possible to effectively perform position-based vehicle control when the position reliability R is high.

[0093] A specific example of position-based vehicle control that takes into account the position reliability R will be described below.

[0094] 6-1. First example: Preview control In a first example, the position-based vehicle control is preview control. In the preview control, position information 94 is used to acquire the position of the wheel 2. If the position reliability R of the position information 94 is low, the accuracy of the position of the wheel 2 will be low. If the accuracy of the position of the wheel 2 is low, there is a risk that the unsprung displacement Zu read from the unsprung displacement map 200 will deviate from the unsprung displacement Zu at the actual position of the wheel 2. This will lead to a decrease in the effectiveness of the preview control, and in some cases may result in excitation of vibration rather than damping of vibration.

[0095] Therefore, the control device 70 flexibly adjusts the gain of the preview control in accordance with the position reliability R of the position information 94. For example, the gain of the preview control is β in the above equation (4).

[0096] FIG. 13 is a conceptual diagram illustrating various examples of preview control according to position reliability R. The horizontal axis represents position reliability R, and the vertical axis represents the gain of the preview control. In example (A) of FIG. 13, the gain of the preview control decreases monotonically as the position reliability R decreases. In example (B) of FIG. 13, the gain of the preview control decreases stepwise as the position reliability R decreases. In example (C) of FIG. 13, preview control is performed when the position reliability R is equal to or greater than a threshold Rth, and is not performed (gain = 0) when the position reliability R is less than the threshold Rth. This can be generalized as follows. Consider a first position reliability R1 and a second position reliability R2 lower than the first position reliability R1 (R1 > R2) as the position reliability R. The control device 70 sets the gain of the preview control for the second position reliability R2 to be lower than the gain of the preview control for the first position reliability R1. This makes it possible to prevent the preview control from being performed inappropriately when the position reliability R is low. Also, it becomes possible to perform the preview control effectively when the position reliability R is high.

[0097] The vibration suppression control may be a combination of preview control and feedback control. In the case of a combination of preview control and feedback control, the control force Fc is expressed, for example, by the following equation (5). Equation (5) corresponds to the above equation (4) with a feedback term related to the feedback control added to the right side. γ is the gain of the feedback control.

[0098]

number

[0099] FIG. 14 shows various examples of the combination of preview control and feedback control. In example (A) of FIG. 14, as the position reliability R decreases, the gain of the preview control decreases monotonically, and instead, the gain of the feedback control increases monotonically. In example (B) of FIG. 14, as the position reliability R decreases, the gain of the preview control decreases stepwise, and instead, the gain of the feedback control increases monotonically. In example (C) of FIG. 14, preview control is performed when the position reliability R is equal to or greater than the threshold Rth, and feedback control is performed instead of preview control when the position reliability R is less than the threshold Rth. This can be generalized as follows: The control device 70 sets the gain of the preview control for the second position reliability R2 to be lower than the gain of the preview control for the first position reliability R1. Furthermore, the control device 70 sets the gain of the feedback control for the second position reliability R2 to be higher than the gain of the feedback control for the first position reliability R1. This makes it possible to prevent the preview control from being performed inappropriately when the position reliability R is low, and also to supplement the effect of the vibration suppression control by the feedback control.

[0100] A combination of preview control and rear preview control is also possible. In rear preview control, it is assumed that the front and rear wheels of the target vehicle 1T pass through the same position. First, when the front wheels pass through the first position, the unsprung displacement Zu is calculated in real time using the method shown in FIG. 3. For convenience, this unsprung displacement Zu is referred to as the front wheel unsprung displacement Zu_f. Then, when the rear wheels pass through the first position, preview control is performed using the previously calculated front wheel unsprung displacement Zu_f instead of the unsprung displacement Zu registered in the unsprung displacement map 200. In rear preview control, there is no need to read the unsprung displacement Zu from the unsprung displacement map 200, and therefore the position information 94 is not used. In other words, the rear preview control is not affected by the position reliability R. Therefore, the gain of the rear preview control may be changed in the same way as the gain of the feedback control shown in FIG. 14. This makes it possible to supplement the effect of the vibration suppression control by the rear preview control when the position reliability R is low.

[0101] 6-2. Second example: Autonomous driving control The control device 70 of the vehicle control system 10 may perform automatic driving control to control automatic driving of the target vehicle 1T. Here, automatic driving means that at least a portion of the steering, acceleration, and deceleration of the target vehicle 1T is performed automatically, independent of the driver's operation. As an example, automatic driving of level 3 or higher may be performed. The control device 70 generates a driving plan based on the driving environment information 90. Examples of the driving plan include maintaining the current driving lane, changing lanes, making right or left turns, and avoiding collisions with objects. More specifically, the driving plan includes a route plan and a speed plan. The route plan is a set of target positions of the target vehicle 1T. The speed plan is a set of target speeds for each target position. The combination of the route plan and the speed plan is also called a target trajectory. In other words, the target trajectory includes the target position and target speed of the target vehicle 1T. The control device 70 performs vehicle driving control so that the target vehicle 1T follows the target trajectory.

[0102] FIG. 15 is a conceptual diagram for explaining an example of autonomous driving control according to position reliability R. The horizontal axis represents position reliability R, and the vertical axis represents the level of autonomous driving control (autonomous driving level). As shown in FIG. 15, the level of autonomous driving control decreases as the position reliability R decreases. This can be generalized as follows. As the position reliability R, consider a first position reliability R1 and a second position reliability R2 that is lower than the first position reliability R1 (R1>R2). The control device 70 sets the level of autonomous driving control for the second position reliability R2 lower than the level of autonomous driving control for the first position reliability R1. This makes it possible to prevent inappropriate autonomous driving control when the position reliability R is low. Furthermore, it becomes possible to implement a high level of autonomous driving control when the position reliability R is high.

[0103] 7. Map Update FIG. 16 is a flowchart showing a map generation / update process that takes into account the position reliability R. In step S400, the map management system 100 (see FIG. 6) acquires the position information 94 of the target vehicle 1T. In step S500, the map management system 100 calculates the position reliability R of the position information 94. The method for calculating the position reliability R is as explained in Section 5 above. The altitude map 400 is stored in advance in the storage device 130 of the map management system 100.

[0104] In step S600, the map management system 100 generates / updates the unsprung displacement map 200 taking into account the position reliability R. For example, if the position reliability R is less than a threshold, the map management system 100 does not generate / update the unsprung displacement map 200 for that position. Only when the position reliability R is equal to or greater than the threshold, the map management system 100 generates / updates the unsprung displacement map 200 for that position. This makes it possible to prevent the accuracy of the unsprung displacement map 200 from decreasing. [Explanation of symbols]

[0105] 1 vehicle 2 wheels 3. Suspension 10 Vehicle Control System 40 Position Sensor 70 Control device 94 Location information 100 Map Management System 200 Unsprung Displacement Map 400 Altitude Map

Claims

1. A vehicle control method for controlling a target vehicle, comprising: acquiring position information including a horizontal position and a vertical position of the target vehicle based on a measurement result by a sensor mounted on the target vehicle; calculating a reliability of the location information; taking into consideration the reliability of the location information, execute a location-based vehicle control that is a control of the target vehicle using the location information; Including, Calculating the reliability of the location information acquiring an altitude of a representative point at the horizontal position of the target vehicle as a sensor-based altitude based on the vertical position included in the position information; acquiring the altitude of the representative point at the horizontal position of the target vehicle as a map-based altitude based on an altitude map that indicates a correspondence relationship between latitude, longitude, and altitude of a road surface; calculating the reliability so that the reliability decreases as the difference between the sensor-based altitude and the map-based altitude increases; Contains Vehicle control method.

2. 2. The vehicle control method according to claim 1, The method further includes lowering the degree of the position-utilizing vehicle control when the reliability is a second reliability lower than the first reliability, compared to the degree of the position-utilizing vehicle control when the reliability is the first reliability. Vehicle control method.

3. 2. The vehicle control method according to claim 1, the location-based vehicle control includes a preview control; The preview control includes: obtaining a vertical motion parameter map indicating a correspondence relationship between vertical motion parameters and positions related to vertical motion of wheels of a vehicle; reading out the vertical movement parameters at the wheel positions of the target vehicle from the vertical movement parameter map based on the position information; controlling the target vehicle based on the vertical movement parameters read from the vertical movement parameter map; Including, The gain of the preview control when the reliability is a second reliability lower than the first reliability is set lower than the gain of the preview control when the reliability is the first reliability. Vehicle control method.

4. 2. The vehicle control method according to claim 1, the location-based vehicle control includes automatic driving control of the target vehicle, The level of the automatic driving control when the reliability is a second reliability lower than the first reliability is set lower than the level of the automatic driving control when the reliability is the first reliability. Vehicle control method.

5. A position reliability calculation method for calculating the reliability of position information of a target vehicle by a computer, comprising: the position information is acquired based on measurement results by a sensor mounted on the target vehicle, and includes a horizontal position and a vertical position of the target vehicle; The location reliability calculation method includes: acquiring an altitude of a representative point at the horizontal position of the target vehicle as a sensor-based altitude based on the vertical position included in the position information; acquiring the altitude of the representative point at the horizontal position of the target vehicle as a map-based altitude based on an altitude map that indicates a correspondence relationship between latitude, longitude, and altitude of a road surface; calculating the reliability so that the reliability decreases as the difference between the sensor-based altitude and the map-based altitude increases; Contains Location reliability calculation method.

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