Map data, map update method, vehicle control method, and vehicle control system

Abstract

To provide map data concerning vertical motion parameters relevant to vertical motion of a wheel of a vehicle, which has proper resolution.SOLUTION: Map data concerning parameters relevant to vertical motion of a wheel of a vehicle has the following structure. That is, the map data has a data structure which shows a vertical motion parameter with respect to each of a plurality of unit areas arranged in a mesh shape. A first mesh width is a width of each unit area along a travelling width of the vehicle. The first mesh width changes depending on a vehicle speed and is set to enlarge as a vehicle speed becomes higher.SELECTED DRAWING: Figure 13

Description

[Technical field]

[0001] The present disclosure relates to map data relating to parameters related to vertical movement of vehicle wheels, to generation / updating of the map data, and to vehicle control using the map data. [Background technology]

[0002] Patent Document 1 discloses a road surface displacement map that indicates the correspondence between road surface displacement (road surface unevenness) and position. Vibration suppression control is performed by utilizing such a road surface displacement map. Specifically, the road surface displacement at a predetermined position in front of the vehicle is recognized in advance from the road surface displacement map. The control amount of the active suspension is calculated in advance according to the recognized road surface displacement. Then, the active suspension is controlled at the timing when the wheel passes the predetermined position, thereby effectively suppressing the vibration of the vehicle. [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 map data regarding vertical movement parameters related to the vertical movement of the wheels of a vehicle. Such map data may be used for vehicle control. If the resolution of the map data is higher than necessary, the amount of map data increases unnecessarily. The unnecessary increase in the amount of map data leads to a waste of resources such as storage resources, communication resources, and computer resources, which is undesirable from the viewpoint of cost, etc.

[0005] One object of the present disclosure is to provide map data with reasonable resolution regarding parameters related to the vertical movement of the wheels of a vehicle.

[0006] Another object of the present disclosure is to provide a technology that can reduce resource consumption in vehicle control using map data regarding parameters related to the up and down movement of the vehicle's wheels. [Means for solving the problem]

[0007] The first aspect relates to map data relating to parameters related to the vertical movement of the wheels of the vehicle. The map data has a data structure that indicates the up-down movement parameters for each of a plurality of unit areas arranged in a mesh pattern. The first mesh width is the width of each unit area along the vehicle travel direction. The first mesh width depends on the vehicle speed, and is set to be larger as the vehicle speed increases.

[0008] A second aspect relates to a map updating method for updating map data relating to a vertical movement parameter related to the vertical movement of a wheel of a vehicle. The map update method includes a process of updating the map data based on time series data of the wheel positions and time series data of the vertical movement parameters. The map data has a data structure that indicates the up-down movement parameters for each of a plurality of unit areas arranged in a mesh pattern. The first mesh width is the width of each unit area along the vehicle travel direction. The first mesh width depends on the vehicle speed, and is set to be larger as the vehicle speed increases. The process of updating the map data includes a process of updating the vertical movement parameters of the unit area corresponding to the wheel position.

[0009] The third aspect relates to a vehicle control method. The vehicle control method includes: obtaining map data relating to vertical movement parameters associated with vertical movement of wheels of a vehicle; A process of controlling a target vehicle based on vertical movement parameters obtained from map data; Includes. The map data has a data structure that indicates the up-down movement parameters for each of a plurality of unit areas arranged in a mesh pattern. The first mesh width is the width of each unit area along the vehicle travel direction. The first mesh width depends on the vehicle speed, and is set to be larger as the vehicle speed increases.

[0010] The fourth aspect relates to a vehicle control system. The vehicle control system includes one or more processors. The one or more processors obtaining map data relating to vertical movement parameters associated with vertical movement of wheels of a vehicle; A process of controlling a target vehicle based on vertical movement parameters obtained from map data; The apparatus is configured to execute the following steps: The map data has a data structure that indicates the up-down movement parameters for each of a plurality of unit areas arranged in a mesh pattern. The first mesh width is the width of each unit area along the vehicle travel direction. The first mesh width depends on the vehicle speed, and is set to be larger as the vehicle speed increases. Effect of the Invention

[0011] According to the first and second aspects, map data is provided that is related to parameters relating to the vertical movement of the wheels of a vehicle and has an appropriate resolution.

[0012] According to the third and fourth aspects, it is possible to reduce resource consumption in vehicle control using map data relating to parameters related to the vertical movement of the wheels of the vehicle. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic diagram illustrating an example of the configuration of a vehicle according to an embodiment. [Diagram 2] 1 is a conceptual diagram showing a configuration example of a suspension according to an embodiment; [Diagram 3] 5 is a flowchart illustrating an example of an unsprung displacement calculation process according to the embodiment. [Figure 4] 1 is a block diagram showing an example of the configuration of a vehicle control system according to an embodiment; [Diagram 5] 4 is a block diagram showing an example of driving environment information according to an embodiment. FIG. [Figure 6] 1 is a block diagram showing an example of a 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] 1 is a flowchart showing an outline of a map generation / update process according to an embodiment. [Figure 9] 11 is a conceptual diagram for explaining preview control using an unsprung displacement map according to an embodiment. FIG. [Figure 10] 10 is a flowchart showing a preview control using an unsprung displacement map according to an embodiment. [Figure 11] 11 is a conceptual diagram for explaining the relationship between the position of unsprung displacement used in the preview control and the vehicle speed. FIG. [Figure 12] FIG. 2 is a schematic diagram for explaining a vehicle traveling direction. [Figure 13] FIG. 4 is a conceptual diagram for explaining a data structure of an unsprung displacement map in the embodiment. [Figure 14] FIG. 4 is a conceptual diagram for explaining a data structure of an unsprung displacement map in the embodiment. [Figure 15] FIG. 2 is a conceptual diagram for explaining a map generation / update process according to an embodiment. [Figure 16] 13 is a flowchart showing an example of a map generation / update process according to the embodiment. [Figure 17] 13 is a flowchart showing another example of the map generation / update process according to the embodiment. [Figure 18] FIG. 11 is a conceptual diagram for explaining a first modified example of the data structure of the unsprung displacement map in the embodiment. [Figure 19] 13 is a flowchart showing yet another example of the map generation / update process according to the embodiment. [Figure 20] FIG. 11 is a conceptual diagram for explaining a second modified example of the data structure of the unsprung displacement map in the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0015] 1. Suspension and vertical movement parameters FIG 1 is a schematic diagram showing an example of the 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 there is a particular need to distinguish between them, each wheel will be referred to as a wheel 2, and each suspension will be referred to as a suspension 3.

[0016] FIG. 2 is a conceptual diagram showing an example of the configuration of a suspension 3. The suspension 3 is provided to connect between an unsprung structure 4 and a sprung structure 5 of a vehicle 1. The unsprung structure 4 includes a 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 damper 3D has a damping coefficient C. The damping force of the damper 3D may be variable. The actuator 3A applies a control force Fc in the vertical direction between the unsprung structure 4 and the sprung structure 5.

[0017] 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.

[0018] 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 the 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', sprung acceleration Zs'', etc. The vertical motion parameters can also be said to be "road surface displacement related parameters" related to the road surface displacement Zr.

[0019] As an example, in the following description, a case where the vertical movement parameter is the unsprung displacement Zu will be considered. When generalizing, the "unsprung displacement" in the following description should be read as the "vertical movement parameter".

[0020] FIG. 3 is a flowchart illustrating an example of the unsprung displacement calculation process.

[0021] 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 displacement Zs is calculated by integrating the sprung acceleration Zs'' twice.

[0022] In step S13, a 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.

[0023] In step S14, in order to suppress the influence of sensor drift and the like, a filtering process is performed on the time series data of the sprung displacement Zs. Similarly, in step S15, a filtering process 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 so as to include the sprung resonance frequency of the vehicle 1. For example, the specific frequency band is 0.3 to 10 Hz.

[0024] In step S16, the difference between the sprung displacement Zs and the stroke ST is calculated as the unsprung displacement Zu.

[0025] 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.

[0026] 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''.

[0027] 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 mounted on a vehicle 1 and controls the vehicle 1. 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.

[0028] The vehicle state sensor 20 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 include a stroke sensor 23 that detects a stroke ST. The vehicle state sensor 20 may 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.

[0029] The recognition sensor 30 recognizes (detects) the surrounding situation of the vehicle 1. Examples of the recognition sensor include a camera, a LIDAR (Laser Imaging Detection and Ranging), and a radar.

[0030] The position sensor 40 detects the position and orientation of the vehicle 1. For example, the position sensor 40 includes a Global Navigation Satellite System (GNSS).

[0031] The communication device 50 communicates with the outside of the vehicle 1 .

[0032] The traveling device 60 includes a steering device 61, a driving device 62, a braking device 63, and a suspension 3 (see FIG. 2). The steering device 61 steers the wheels 2. For example, the steering device 61 includes an electric power steering (EPS) device. The driving device 62 is a power source that generates a driving force. Examples of the driving device 62 include an engine, an electric motor, and an in-wheel motor. The braking device 63 generates a braking force.

[0033] The control device 70 is a computer that controls the vehicle 1. 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 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), and an SSD (Solid State Drive). The control device 70 may include one or more ECUs (Electronic Control Units).

[0034] 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 in a computer-readable recording medium. The processor 71 executes the vehicle control program 80 to realize the functions of the control device 70.

[0035] 2-2. Driving environment information 5 is a block diagram showing an example of driving environment information 90 indicating 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 position information 94.

[0036] 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 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 mounted on 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.

[0037] The map information 91 further includes an "unsprung displacement map 200." The unsprung displacement map 200 will be described in detail later.

[0038] The vehicle state information 92 is information indicating 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 that case, the vehicle state information 92 also includes the unsprung displacement Zu calculated by the control device 70.

[0039] The surrounding situation information 93 is information indicating 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 a LIDAR.

[0040] The surrounding situation information 93 further includes "object information" regarding 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, median strips, 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.

[0041] The position information 94 is information indicating the position and orientation (vehicle traveling direction) of the vehicle 1. The control device 70 acquires the position information 94 from a measurement result by the 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 the highly accurate position information 94 by a well-known self-position estimation process (Localization) using the object information and the map information 91.

[0042] 2-3.Vehicle control The control device 70 executes 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 executes vehicle driving control by controlling the driving device 60 (the steering device 61, the drive device 62, and the braking device 63). The control device 70 may execute 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.

[0043] Furthermore, the control device 70 controls the suspension 3. Typically, the control device 70 performs vibration suppression control to suppress vibration of the vehicle 1 by controlling the suspension 3. For example, the control device 70 controls the actuator 3A to generate a vertical control force Fc 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" to be described later.

[0044] 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, update, 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.

[0045] 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 number of vehicles 1 via the communication network NET.

[0046] The map management system 100 further includes one or more processors 120 (hereinafter simply referred to as processor 120) and one or more storage devices 130 (hereinafter simply referred to as storage device 130). The processor 120 executes various types of information processing. For example, the processor 120 includes a CPU. 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.

[0047] 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 in a computer-readable recording medium. The processor 120 executes the map management program 140 to realize the functions of the map management system 100.

[0048] 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.

[0049] 3-2.Unsprung displacement map One of the map information managed by the map management system 100 is an “unsprung displacement map (vertical movement parameter map) 200.” The unsprung displacement map 200 is a map related to unsprung displacement Zu (vertical movement parameter). The unsprung displacement map 200 is stored in the storage device 130.

[0050] 7 is a conceptual diagram for explaining the unsprung displacement map 200. For example, an absolute coordinate system in a horizontal plane is defined by latitude and longitude directions, and a position is defined by latitude LAT and longitude LON. The unsprung displacement map 200 represents at least the correspondence relationship between the position (LAT, LON) 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 position (LAT, LON).

[0051] The road area may be divided into a mesh shape 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 has, for example, a rectangular shape. 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 (e.g., a central position) of the unit area M, 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, an 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 is. The optimization of the resolution of the unsprung displacement map 200 will be described in detail later.

[0052] 3-3. Map generation / update processing The processor 120 collects information from multiple 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 multiple vehicles 1. An example of the map generation / update process will be described in more detail below.

[0053] The positions in the unsprung displacement map 200 are positions through which the wheels 2 have passed. 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 the relative positional relationship and the vehicle position indicated by the position information 94, the position of each wheel 2 can be calculated.

[0054] 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 called "sensor-based information." The unsprung displacement Zu is calculated based on this sensor-based information.

[0055] 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 the sensor-based information. The control device 70 also associates the wheel position and the unsprung displacement Zu at the same timing. Then, the control device 70 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.

[0056] As another example, the control device 70 of the vehicle control system 10 associates the wheel positions and the sensor-based information at the same timing. 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.

[0057] In addition, when the unsprung displacement Zu is calculated in the map management system 100, since there is no restriction on the processing time, a filtering process can be performed using a zero phase filter. By using the zero phase filter, it is possible to prevent a "phase shift".

[0058] FIG. 8 is a flowchart outlining the map generation / update process according to this embodiment.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] Fig. 9 is a conceptual diagram for explaining preview control, and Fig. 10 is a flowchart showing preview control. Preview control will be explained with reference to Figs.

[0064] 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 the relative positional relationship and the vehicle position indicated by the position information 94, the position of each wheel 2 can be calculated.

[0065] 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 to, for example, a time required for calculation processing and communication processing required to operate the actuator 3A of the suspension 3 or more. 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.

[0066] 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.

[0067] In step S34, the control device 70 calculates a target control force Fc_t of the actuator 3A of the suspension 3 based on the unsprung displacement Zu at the predicted passing position Pf. The target control force Fc_t is calculated, for example, as follows.

[0068] The equation of motion for the sprung structure 5 (see FIG. 2) is expressed by the following equation (1).

[0069]

number

[0070] 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 by the control force Fc (Zs''=0, Zs'=0, Zs=0), the control force Fc is expressed by the following equation (2).

[0071]

number

[0072] The control force Fc that provides at least the vibration damping effect is expressed by the following formula (3).

[0073]

number

[0074] In formula (3), the gain α is greater than 0 and less than or equal to 1, and the gain β is also greater than 0 and less than or equal to 1. When the differential term in formula (3) is omitted, a control force Fc that provides at least a vibration damping effect is expressed by the following formula (4).

[0075]

number

[0076] 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).

[0077] 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 known from the preview time tp.

[0078] By the preview control using the unsprung displacement map 200 described above, it becomes possible to effectively suppress vibrations of the vehicle 1 (sprung structure 5).

[0079] 5. Optimization of the resolution of the unsprung displacement map 7, the unsprung displacement map 200 has a data structure that indicates the unsprung displacement Zu for each of a plurality of unit areas M arranged in a mesh (array). The smaller the unit area M, the higher the resolution of the unsprung displacement map 200.

[0080] However, if the resolution of the unsprung displacement map 200 is higher than necessary, the amount of map data increases unnecessarily. An unnecessary increase in the amount of map data leads to a waste of resources such as storage resources, communication resources, and computer resources, which is undesirable from the viewpoint of costs, etc. Therefore, the following will consider optimizing the resolution of the unsprung displacement map 200.

[0081] FIG. 11 is a conceptual diagram for explaining the relationship between the position of the unsprung displacement Zu used in the above-mentioned preview control and the vehicle speed V. The vertical axis represents the unsprung displacement Zu, and the horizontal axis represents the position on the path through which the wheel 2 passes. It is assumed that the control period is constant regardless of the vehicle speed V. As shown in FIG. 11, the interval between the positions of the unsprung displacement Zu used in the preview control becomes narrower as the vehicle speed V decreases, and becomes wider as the vehicle speed V increases. Therefore, when the vehicle speed V is low, a relatively high resolution of the unsprung displacement map 200 is required to ensure the accuracy of the preview control. On the other hand, when the vehicle speed V is high, the accuracy of the preview control is ensured even if the resolution of the unsprung displacement map 200 is relatively low. Rather, a resolution equivalent to that at low vehicle speeds is excessive, which leads to an unnecessary increase in the amount of map data and a waste of resources.

[0082] From the above viewpoint, according to this embodiment, the resolution of the unsprung displacement map 200 is optimized in consideration of the vehicle speed V.

[0083] 5-1. Data structure of unsprung displacement map First, the "vehicle travel direction X" used in the following description will be described with reference to Fig. 12. The vehicle travel direction X is the travel direction of the vehicle 1 (wheels 2). The lateral direction Y is a direction perpendicular to the vehicle travel direction X in a horizontal plane. The vehicle travel direction X is obtained from the above-mentioned position information 94.

[0084] Approximately, the lane direction LD may be used as the vehicle travel direction X (X=LD). The lane direction LD is the direction in which the lane on which the vehicle 1 travels extends. The lane direction LD coincides with the direction of the lane boundary LB, such as a white line or a curb. The lane direction LD is obtained from map information 91 of the surroundings of the vehicle 1. Alternatively, the lane direction LD (the direction of the lane boundary LB) may be recognized based on surrounding situation information 93 (object information).

[0085] FIG. 13 is a conceptual diagram for explaining the data structure of the unsprung displacement map 200 having an appropriate resolution. The unsprung displacement map 200 has a data structure showing the unsprung displacement Zu for each of a plurality of unit areas M arranged in a mesh (array). Each unit area M has a rectangular shape, and the rectangular shape has a first side Sx and a second side Sy that are perpendicular to each other. The first side Sx is parallel to the vehicle traveling direction X. On the other hand, the second side Sy is parallel to the lateral direction Y and perpendicular to the vehicle traveling direction X. The first mesh width Wx is the width of the first side Sx, that is, the width of the unit area M along the vehicle traveling direction X. The second mesh width Wy is the width of the second side Sy, that is, the width of the unit area M along the lateral direction Y.

[0086] According to this embodiment, the first mesh width Wx in the vehicle travel direction X is set to depend on the vehicle speed Vm. Here, the "vehicle speed Vm" is a reference vehicle speed for defining the first mesh width Wx. For example, the vehicle speed Vm is the actual vehicle speed V when the map update information is acquired. Alternatively, the vehicle speed Vm defining the first mesh width Wx of the unit area M in a predetermined area may be a representative vehicle speed in the predetermined area. Examples of the representative vehicle speed include a predetermined speed limit and an average vehicle speed obtained statistically. The first mesh width Wx of the unit area M is expressed as a function of such a vehicle speed Vm (Wx=f(Vm)). More specifically, the first mesh width Wx is set to be larger as the vehicle speed Vm increases and to be smaller as the vehicle speed Vm decreases. That is, the higher the vehicle speed Vm, the lower the resolution of the unsprung displacement map 200 in the vehicle travel direction X. This makes it possible to reduce the amount of map data while ensuring sufficient preview control accuracy.

[0087] A specific example of the first mesh width Wx is as follows. Assume that the cutoff frequency of the low-pass filter used in creating the map is, for example, 10 Hz. Considering the Nyquist frequency, it is preferable to set the first mesh width Wx so as to obtain data of about twice the cutoff frequency of the low-pass filter. For example, when the vehicle speed Vm is 36 km / h (10 m / s), the first mesh width Wx is set to 50 cm so as to obtain data of 20 Hz. As another example, when the vehicle speed Vm is 72 km / h (20 m / s), the first mesh width Wx is set to 1 m so as to obtain data of 20 Hz.

[0088] On the other hand, the second mesh width Wy in the lateral direction Y does not depend on the vehicle speed Vm. Typically, the second mesh width Wy is a fixed width. Regarding the lateral direction Y, if the position is shifted by more than the tire width, it will become a different road surface, so high resolution is required to ensure the accuracy of the preview control. For example, the second mesh width Wy is set to a value smaller than the tire width. For example, the second mesh width Wy is set to 10 cm. This ensures sufficient control accuracy in the lateral direction Y.

[0089] Typically, as shown in FIG. 13, the first mesh width Wx in the vehicle travel direction X is larger than the second mesh width Wy in the lateral direction Y (Wx>Wy).

[0090] FIG. 14 shows the unsprung displacement map 200 for different areas. The vehicle speed Vm in the first area A1 is higher than the vehicle speed Vm in the second area A2. The first mesh width Wx1 of the unit area M included in the first area A1 is larger than the first mesh width Wx2 of the unit area M included in the second area A2. On the other hand, the second mesh width Wy does not depend on the vehicle speed Vm and is the same in the first area A1 and the second area A2. That is, the second mesh width Wy is uniform, but the first mesh width Wx is not uniform but varies according to the vehicle speed Vm.

[0091] As described above, according to this embodiment, the resolution of the unsprung displacement map 200 is optimized. The first mesh width Wx of the unit area M along the vehicle traveling direction X is not constant, but is set to be larger as the vehicle speed Vm increases. That is, the resolution of the unsprung displacement map 200 in the vehicle traveling direction X decreases as the vehicle speed Vm increases. This reduces the amount of map data, and suppresses consumption of resources such as storage resources, communication resources, and computer resources. In addition, even if the resolution in the vehicle traveling direction X decreases according to the vehicle speed Vm, the preview control accuracy is sufficiently ensured. In this way, according to this embodiment, it is possible to reduce the amount of map data and suppress resource consumption while ensuring the preview control accuracy. This is preferable from the viewpoint of cost and the like.

[0092] 5-2. Map generation / update processing Next, the map generation / update process taking into consideration the vehicle speed Vm and the vehicle traveling direction X will be described.

[0093] As already shown in FIG. 8, in step S100, the processor 120 of the map management system 100 acquires map update information from the vehicle control system 10. The map update information includes time series data of the position (wheel position) of the vehicle 1. The map update information also includes sensor-based information or time series data of the unsprung displacement Zu. Furthermore, the map update information includes information of the vehicle speed V and the vehicle traveling direction X when the map update information was obtained. In step S200, the processor 120 generates / updates the unsprung displacement map 200 based on the map update information.

[0094] Fig. 15 is a conceptual diagram for explaining step S200. Fig. 16 is a flowchart showing step S200. Step S200 will be explained with reference to Figs. 15 and 16.

[0095] In step S210, the processor 120 acquires information on the vehicle speed Vm and the vehicle traveling direction X from the map update information. The vehicle speed Vm is the vehicle speed V when the map update information is acquired. Alternatively, the vehicle speed Vm may be a representative vehicle speed (e.g., a speed limit or an average vehicle speed) in a predetermined area. In the latter case, the vehicle speed Vm may be acquired from a database separately prepared.

[0096] In step S230, the processor 120 sets the unit area M and its mesh width based on the vehicle speed Vm and the vehicle traveling direction X. Specifically, the unit area M is set to have a rectangular shape having a first side Sx parallel to the vehicle traveling direction X and a second side Sy perpendicular to the vehicle traveling direction X. The first mesh width Wx along the vehicle traveling direction X is set to be variable according to the vehicle speed Vm. More specifically, the first mesh width Wx along the vehicle traveling direction X is set to be larger as the vehicle speed Vm increases. On the other hand, the second mesh width Wy perpendicular to the vehicle traveling direction X is set to a fixed width that does not depend on the vehicle speed Vm.

[0097] In step S240, the processor 120 updates the unsprung displacement Zu of the unit area M corresponding to the wheel position. The unsprung displacement Zu of the unit area M is, for example, an average value of the unsprung displacement Zu acquired within the unit area M.

[0098] It is possible that a large amount of map update information for the same location may be obtained as one or more vehicles 1 repeatedly pass the same location. The history of the map update information is stored in the storage device 130 of the map management system 100. In this case, the processor 120 may update the size and arrangement of the unit area M in the area each time new map update information for the same area is obtained. For example, the processor 120 may set the unit area M based on the average or weighted average of the vehicle speed Vm and the vehicle traveling direction X for the most recent N times (N is an integer equal to or greater than 2).

[0099] As yet another example, the size and arrangement of unit areas M in a predetermined area may be determined in advance. In this case, for example, the lane direction LD is used as the vehicle travel direction X (see FIG. 12). In addition, a representative vehicle speed within the predetermined area is used as the vehicle speed Vm for defining the first mesh width Wx. Examples of the representative vehicle speed include a predetermined speed limit and a statistically obtained average vehicle speed. FIG. 17 is a flowchart showing step S200 in this example. In this example, steps S210 and S230 are omitted.

[0100] 5-3. Vehicle control using unsprung displacement map The unsprung displacement map 200 is used for vehicle control such as preview control, etc. For convenience, the vehicle 1 that is the target of the vehicle control is called a "target vehicle 1T."

[0101] The vehicle control system 10 of the target vehicle 1T acquires the unsprung displacement map 200 of the area including the current position of the target vehicle 1T from the map management system 100 via communication. Then, the vehicle control system 10 acquires the unsprung displacement Zu of the unit area M through which the wheels 2 of the target vehicle 1T pass, from the unsprung displacement map 200. The vehicle control system 10 controls the target vehicle 1T based on the acquired unsprung displacement Zu. For example, the vehicle control is preview control (see Figs. 9 and 10).

[0102] Since the resolution of the unsprung displacement map 200 is optimized and the amount of map data is reduced, the amount of data communication is reduced. Also, the processing load on the vehicle control system 10 is reduced. In particular, when driving at high speeds, a larger map area is required per unit time, but at the same time, the map resolution is lowered, so that an increase in the amount of data communication and the processing load is suppressed. This suppresses the consumption of communication resources and computer resources.

[0103] 5-4.Modifications 5-4-1. First modified example 18 is a conceptual diagram for explaining a first modified example of the data structure of the unsprung displacement map 200. In the first modified example, for the same area, different unsprung displacement maps 200 are prepared for each vehicle speed range.

[0104] As an example, consider a first vehicle speed range and a second vehicle speed range that do not overlap each other. The unsprung displacement map 200 includes a first layer map data 200-V1 for the first vehicle speed range and a second layer map data 200-V2 for the second vehicle speed range for the same area. That is, the unsprung displacement map 200 is multi-layered. When the first vehicle speed range is higher than the second vehicle speed range, the first mesh width Wx of the unit area M in the first layer map data 200-V1 is larger than the first mesh width Wx of the unit area M in the second layer map data 200-V2.

[0105] FIG. 19 is a flowchart showing the map generation / update process (step S200) in the case of the first modified example. Compared with the process flow shown in FIG. 16, step S220 is added. In step S220, the processor 120 selects layer map data 200-Vj (j=1 or 2) corresponding to the vehicle speed Vm. If layer map data 200-Vj corresponding to the vehicle speed Vm does not yet exist, the processor 120 newly creates layer map data 200-Vj corresponding to the vehicle speed Vm. The subsequent steps S230 and S240 are performed on the selected layer map data 200-Vj.

[0106] The vehicle control is as follows: The vehicle control system 10 of the target vehicle 1T acquires the layer map data 200-Vj corresponding to the current vehicle speed V from the map management system 100. Then, the vehicle control system 10 performs vehicle control such as preview control using the layer map data 200-Vj.

[0107] The same applies when the number of vehicle speed ranges is three or more.

[0108] 5-4-2. Second modified example FIG. 20 is a conceptual diagram for explaining a second modified example of the data structure of the unsprung displacement map 200. In the second modified example, an intersection where a first road R1 and a second road R2 intersect is considered. The first vehicle travel direction X1 is the vehicle travel direction X along the first road R1. On the other hand, the second vehicle travel direction X2 is the vehicle travel direction X along the second road R2. The unsprung displacement map 200 at the intersection includes a first layer map data 200-X1 for the first vehicle travel direction X1 and a second layer map data 200-X2 for the second vehicle travel direction. That is, the unsprung displacement map 200 is multi-layered.

[0109] In the map generation / update process, the vehicle travel direction X at the time when the map update information is obtained is taken into consideration. When the vehicle travel direction X is the first vehicle travel direction X1, the first layer map data 200-X1 is selected and updated. On the other hand, when the vehicle travel direction X is the second vehicle travel direction X2, the second layer map data 200-X2 is selected and updated.

[0110] In vehicle control, the vehicle travel direction X when the target vehicle 1T passes through the intersection is taken into consideration. When the vehicle travel direction X is the first vehicle travel direction X1, the first layer map data 200-X1 is selected and used for vehicle control. On the other hand, when the vehicle travel direction X is the second vehicle travel direction X2, the second layer map data 200-X2 is selected and used for vehicle control.

[0111] 5-4-3.Third modified example A combination of the first and second modifications is also possible. [Explanation of symbols]

[0112] 1 vehicle 2 wheels 3. Suspension 10 Vehicle Control System 20 Vehicle condition sensor 30 Recognition Sensor 40 Position Sensor 50 Communication equipment 60 Running gear 70 Control device 80 Vehicle Control Program 90 Driving Environment Information 93 Surrounding Area Information 94 Location information 100 Map Management System 110 Communication equipment 120 processors 130 Storage device 140 Map Management Program 200 Unsprung Displacement Map 200-V1, 200-X1 1st layer map data 200-V2, 200-X2 2nd layer map data M unit area Sx 1st side Sy 2nd side Wx 1st mesh width Wy Second mesh width X Vehicle travel direction Y Horizontal Zu Unsprung Displacement

Claims

1. A vehicle control system for controlling a target vehicle, comprising: a map management system that manages map data relating to vertical movement parameters associated with vertical movement of wheels of a vehicle; the map data managed by the map management system has a data structure indicating the vertical movement parameters for each of a plurality of unit areas arranged in a mesh pattern, The first mesh width is a width of each of the unit areas along a vehicle traveling direction, the first mesh width is dependent on a reference vehicle speed that is set when the map data is generated in the map management system, and is set to be larger as the reference vehicle speed becomes higher; The one or more processors further include: acquiring the map data of the area including the current position of the target vehicle from the map management system via communication; The vertical movement parameters of a unit area through which the wheels of the target vehicle pass are obtained from the map data; Controlling the target vehicle based on the vertical movement parameters obtained from the map data It was configured as Vehicle control system.

2. 2. The vehicle control system according to claim 1, a second mesh width is a width of each of the unit areas along a lateral direction perpendicular to the vehicle traveling direction, The second mesh width is a fixed width that does not depend on the reference vehicle speed. Vehicle control system.

3. 3. The vehicle control system according to claim 2, The first mesh width is larger than the second mesh width. Vehicle control system.

4. A vehicle control system according to any one of claims 1 to 3, The vehicle travel direction is the lane direction. Vehicle control system.

5. A vehicle control system according to any one of claims 1 to 4, The reference vehicle speed that defines the first mesh width of the unit area within a predetermined area is the speed limit or average vehicle speed in the predetermined area. Vehicle control system.

6. A vehicle control system according to any one of claims 1 to 5, the reference vehicle speed in a first area is higher than the reference vehicle speed in a second area different from the first area, The first mesh width of the unit area included in the first area is larger than the first mesh width of the unit area included in the second area. Vehicle control system.

7. A vehicle control system according to any one of claims 1 to 6, the map data managed by the map management system has a data structure including, for a same area, first layer map data for a first vehicle speed range and second layer map data for a second vehicle speed range lower than the first vehicle speed range, The first mesh width of the unit area in the first layer map data is larger than the first mesh width of the unit area in the second layer map data. Vehicle control system.

Images