Vehicle control method and vehicle control system

Abstract

To provide a technique that can improve robustness against degradation of communication quality, with regard to vehicle control utilizing a parameter map showing a correspondence relationship between a parameter associated with vertical motion of a wheel and a position.SOLUTION: A vehicle control system controls a vehicle according to a parameter map which shows a correspondence relationship between a parameter related to vertical motion of a wheel and a position. The vehicle control system communicates with a map management system which manages the parameter map, and downloads a thinned-out map in which a portion of data in a vehicle travel direction has been thinned out from the parameter map. In addition, the vehicle control system acquires the parameter at an object position while interpolating at least a part of the thinned-out portion in the thinned-out map along the vehicle travel direction. Then, the vehicle control system controls a vehicle according to the parameter at the object position.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present disclosure relates to vehicle control using a parameter map that indicates the correspondence between parameters related to the vertical movement of wheels and positions. [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 vehicle control using a parameter map that indicates the correspondence between parameters related to the vertical movement of the wheels and positions. Typically, the parameter map is managed by a map management system outside the vehicle. Vehicle control is performed by communicating with the map management system and sequentially downloading parameter maps of required areas from the map management system. Here, if communication quality (communication speed, communication delay, etc.) deteriorates, there is a risk that the parameter map required for vehicle control cannot be obtained by the time vehicle control is executed. In that case, vehicle control using the parameter map cannot be continued.

[0005] One objective of the present disclosure is to provide a technology that can improve robustness against deterioration of communication quality in vehicle control using a parameter map that represents the correspondence between parameters related to the up and down movement of wheels and position. [Means for solving the problem]

[0006] The first aspect relates to a vehicle control method for controlling a vehicle based on a parameter map that indicates a correspondence relationship between a parameter related to the vertical movement of a wheel and a position. The vehicle control method includes: A process of communicating with a map management system that manages a parameter map, and downloading a thinned map in which a portion of data in the vehicle travel direction is thinned out from the parameter map; A process of acquiring parameters of a target position while interpolating at least a part of a thinned-out portion in the thinned-out map along a vehicle traveling direction; controlling the vehicle based on the target position parameters; Includes.

[0007] The second aspect relates to a vehicle control system that controls a vehicle based on a parameter map that indicates the correspondence between a parameter related to the vertical movement of a wheel and a position. The vehicle control system includes one or more processors. The one or more processors A process of communicating with a map management system that manages a parameter map, and downloading a thinned map in which a portion of data in the vehicle travel direction is thinned out from the parameter map; A process of acquiring parameters of a target position while interpolating at least a part of a thinned-out portion in the thinned-out map along a vehicle traveling direction; controlling the vehicle based on the target position parameters; The apparatus is configured to execute the following steps: Effect of the Invention

[0008] According to the present disclosure, a thinned map is downloaded from a map management system. Thus, the amount of data communication is reduced. Thus, even in a situation where communication quality is degraded, it is highly likely that a thinned map of a necessary area can be obtained by the timing of execution of vehicle control. When the thinned map is obtained, an interpolation process is performed on the thinned map, and the data after the interpolation process is used for vehicle control. Thus, it is possible to continue vehicle control without significantly impairing the accuracy of the vehicle control. In this way, it is possible to improve robustness against deterioration of communication quality while ensuring the accuracy of vehicle control. [Brief description of the drawings]

[0009] [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] FIG. 2 is a schematic diagram for explaining a vehicle traveling direction. [Figure 12]FIG. 2 is a conceptual diagram for explaining an overview of vehicle control based on a thinning map according to an embodiment. [Figure 13] 5 is a flowchart illustrating vehicle control based on a thinning map according to an embodiment. [Figure 14] FIG. 11 is a conceptual diagram for explaining an example of a thinning map according to the embodiment. [Figure 15] 13 is a flowchart showing an example of an interpolation process (step S320) according to the embodiment. [Figure 16] FIG. 11 is a conceptual diagram for explaining an example of the interpolation process (step S320) according to the embodiment. [Figure 17] FIG. 11 is a conceptual diagram for explaining another example of the interpolation process (step S320) according to the embodiment. [Figure 18] FIG. 4 is a conceptual diagram for explaining an example of a divided unsprung displacement map according to the embodiment. [Figure 19] FIG. 10 is a conceptual diagram for explaining another example of the divided unsprung displacement map according to the embodiment. [Figure 20] 13 is a flowchart showing an example of a download process (step S310) according to the embodiment. [Figure 21] FIG. 11 is a conceptual diagram for explaining an example of the interpolation process (step S320) according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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".

[0016] FIG. 3 is a flowchart illustrating an example of the unsprung displacement calculation process.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] In step S16, the difference between the sprung displacement Zs and the stroke ST is calculated as the unsprung displacement Zu.

[0021] 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.

[0022] 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''.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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).

[0027] The communication device 50 communicates with the outside of the vehicle 1 .

[0028] 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.

[0029] 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).

[0030] 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.

[0031] 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.

[0032] 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.

[0033] The map information 91 further includes an "unsprung displacement map 200." The unsprung displacement map 200 will be described in detail later.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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).

[0047] 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. For example, the unit area M is a square with a length of one side of 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 (e.g., a central position) of the unit area M, or may be defined by the range (latitude range, longitude range) of the unit area M. 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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".

[0054] FIG. 8 is a flowchart outlining the map generation / update process according to this embodiment.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] The equation of motion for the sprung structure 5 (see FIG. 2) is expressed by the following equation (1).

[0065]

number

[0066] 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).

[0067]

number

[0068] The control force Fc that provides at least the vibration damping effect is expressed by the following formula (3).

[0069]

number

[0070] 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).

[0071]

number

[0072] 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).

[0073] 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.

[0074] 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).

[0075] 5. Vehicle control based on thinning map Vehicle control such as preview control using the unsprung displacement map 200 will be further considered. The vehicle control system 10 communicates with the map management system 100 and executes vehicle control by successively downloading the unsprung displacement map 200 of the required area from the map management system 100. Here, if communication quality (communication speed, communication delay, etc.) deteriorates, there is a risk that the unsprung displacement map 200 required for vehicle control cannot be obtained by the timing of execution of vehicle control. In that case, it becomes impossible to continue vehicle control using the unsprung displacement map 200.

[0076] Therefore, this embodiment further proposes a technique that can improve robustness against deterioration of communication quality with respect to vehicle control using the unsprung displacement map 200. As described later, according to this embodiment, vehicle control is performed based on the "thinning map 200D."

[0077] First, the "vehicle travel direction X" used in the following description will be described with reference to Fig. 11. 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.

[0078] 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).

[0079] Next, an overview of vehicle control based on the thinned map 200D will be described with reference to Fig. 12 and Fig. 13. As shown in Fig. 12, the map management system 100 manages an unsprung displacement map 200. The "thinned map 200D" is a map obtained by thinning out a part of the data in the vehicle travel direction X from the original unsprung displacement map 200 managed by the map management system 100.

[0080] FIG. 13 is a flowchart showing vehicle control based on the thinning map 200D.

[0081] In step S310, the vehicle control system 10 of the vehicle 1 communicates with the map management system 100. Then, the vehicle control system 10 downloads the thinned map 200D in place of the original unsprung displacement map 200 in the required area. For example, the vehicle control system 10 notifies the map management system 100 of information on the required area and the vehicle traveling direction X, and requests the thinned map 200D of the required area. In response to the request, the map management system 100 transmits the thinned map 200D of the required area to the vehicle control system 10. The vehicle control system 10 holds the received thinned map 200D.

[0082] In step S320, the vehicle control system 10 performs an "interpolation process" to interpolate at least a part of the thinned-out portion in the thinned-out map 200D along the vehicle traveling direction X. The vehicle control system 10 acquires the unsprung displacement Zu of the target position while performing such an interpolation process. For example, in the case of the above-mentioned preview control, the target position is the predicted passing position Pf of the wheel 2 after the preview time tp (see FIG. 9 and FIG. 10).

[0083] In step S330, the vehicle control system 10 performs vehicle control based on the unsprung displacement Zu of the target position. For example, the vehicle control system 10 performs preview control based on the unsprung displacement Zu of the predicted passing position Pf of the wheel 2.

[0084] As described above, according to this embodiment, the thinned map 200D is downloaded from the map management system 100 instead of the original unsprung displacement map 200. Therefore, the amount of data communication is reduced. Therefore, even in a situation where communication quality (communication speed, communication delay, etc.) is deteriorated, the thinned map 200D of the required area is likely to be obtained by the timing of executing vehicle control. When the thinned map 200D is obtained, an interpolation process is performed in the vehicle control system 10, and the data after the interpolation process is used for vehicle control. Therefore, it is possible to continue vehicle control without significantly impairing the accuracy of the vehicle control. In this way, it is possible to improve robustness against deterioration of communication quality while ensuring the accuracy of vehicle control.

[0085] Furthermore, since the amount of data communication is reduced, consumption of communication resources and memory resources is suppressed.

[0086] Various examples of vehicle control based on the thinning map 200D will be described in more detail below.

[0087] 5-1. First method 5-1-1. Thinning map FIG. 14 is a conceptual diagram for explaining an example of the thinned map 200D. The original unsprung displacement map 200 shows the unsprung displacement Zu for each of a plurality of unit areas M arranged in a mesh (array). The unit area M has, for example, a rectangular shape. For example, the unit area M is a square with one side having a length of 10 cm. The thinned map 200D is obtained by thinning out a part of the data in the vehicle traveling direction X from the unsprung displacement map 200. The thinned portion DEC means the part that has been thinned out from the original unsprung displacement map 200. The original portion ORG is the part other than the thinned portion DEC, and is the same as the original unsprung displacement map 200.

[0088] 14, the thinned map 200D is obtained by periodically thinning out a portion of the data in the vehicle traveling direction X from the unsprung displacement map 200. In this case, the original portion ORG of the thinned map 200D appears periodically in the vehicle traveling direction X.

[0089] The intervals between the positions of the unsprung displacement Zu used in the preview control become narrower as the vehicle speed V decreases and wider as the vehicle speed V increases. In other words, when the vehicle speed V is low, spatially fine data is required, but when the vehicle speed V is high, the accuracy of the preview control is ensured even with spatially coarse data. From this perspective, the amount of data to be thinned out, i.e., the thinned out portion DEC, may vary according to the vehicle speed V. More specifically, the higher the vehicle speed V, the larger the thinned out portion DEC may be.

[0090] A specific example of the amount of thinned data is as follows. Suppose 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 obtain data that is about twice the cutoff frequency of the low-pass filter. For example, when the vehicle speed V is 36 km / h (10 m / s), the original portion ORG should remain at a period of 50 cm so that data of 20 Hz can be obtained. As another example, when the vehicle speed V is 72 km / h (20 m / s), the original portion ORG should remain at a period of 100 cm so that data of 20 Hz can be obtained.

[0091] When driving at high speeds, the map area required per unit time becomes larger, but at the same time, the amount of data thinning also increases, so the increase in data communication volume is suppressed. In other words, it is possible to efficiently suppress data communication volume while ensuring vehicle control accuracy.

[0092] 5-1-2. Processing example In step S310 (see FIG. 13), the vehicle control system 10 downloads the thinned map 200D for the necessary area. For example, the vehicle control system 10 notifies the map management system 100 of information on the necessary area and the vehicle traveling direction X. Furthermore, the vehicle control system 10 may notify the map management system 100 of information on the vehicle speed V. The map management system 100 transmits the thinned map 200D for the necessary area to the vehicle control system 10. Preferably, the map management system 100 changes the amount of thinned data depending on the vehicle speed V.

[0093] In step S320, the vehicle control system 10 performs an interpolation process on the thinned map 200D. Specifically, the vehicle control system 10 interpolates at least a part of the thinned portion DEC in the thinned map 200D along the vehicle traveling direction X. That is, the vehicle control system 10 interpolates the thinned portion DEC sandwiched between the original portions ORG in the vehicle traveling direction X by using the data of the original portions ORG.

[0094] 15 and 16 are a flowchart and a conceptual diagram, respectively, for explaining an example of the interpolation process (step S320).

[0095] In step S321, the vehicle control system 10 estimates a future trajectory TR of the wheels 2 of the vehicle 1. The trajectory TR of the wheels 2 can be estimated based on the vehicle speed V, the steering angle, etc. The vehicle speed V and the steering angle are obtained from the vehicle state information 92.

[0096] In step S322, the vehicle control system 10 interpolates the thinned-out portion DEC on the estimated trajectory TR along the vehicle traveling direction X (see FIG. 16). The interpolated data INT is data interpolated by the interpolation process. In the example shown in FIG. 16, the interpolated data INT is added along the estimated trajectory TR. The interpolation process is not performed on the portion other than the trajectory TR.

[0097] FIG. 17 is a conceptual diagram for explaining another example of the interpolation process (step S320). In the example shown in FIG. 17, the thinned-out portion DEC is entirely interpolated along the vehicle traveling direction X. In this case, there is no need to estimate the trajectory TR of the wheel 2. However, since there are more parts to be interpolated, the load of the interpolation process may increase compared to the case of FIG. 16. From the viewpoint of reducing the load of the interpolation process, the method shown in FIG. 16 is preferable.

[0098] 5-2. Second method 5-2-1. Split unsprung displacement map (split parameter map) In the second technique, the unsprung displacement map 200 is configured by combining a plurality of divided unsprung displacement maps (divided parameter maps) 200D-1 to 200D-N, where N is an integer of 2 or more.

[0099] FIG. 18 is a conceptual diagram for explaining an example of a divided unsprung displacement map 200D-j (j=1 to N). Each divided unsprung displacement map 200D-j is a map in which at least a part of the data in the vehicle traveling direction X is thinned out from the unsprung displacement map 200. In other words, each divided unsprung displacement map 200D-j corresponds to a thinned map 200D. The arrangement of the original portion ORG is different among the divided unsprung displacement maps 200D-1 to 200D-N. When all the divided unsprung displacement maps 200D-1 to 200D-N are combined, the original unsprung displacement map 200 is restored. In the example shown in FIG. 18, the original portion ORG extends in the lateral direction Y perpendicular to the vehicle traveling direction X.

[0100] Fig. 19 is a conceptual diagram for explaining another example of the divided unsprung displacement map 200D-j. In the example shown in Fig. 19, each divided unsprung displacement map 200D-j has original portions ORG arranged in a mosaic pattern. Even in this case, each divided unsprung displacement map 200D-j is a map in which at least a part of the data in the vehicle travel direction X is thinned out from the unsprung displacement map 200. The arrangement of the original portions ORG differs among the divided unsprung displacement maps 200D-1 to 200D-N. When all the divided unsprung displacement maps 200D-1 to 200D-N are combined, the original unsprung displacement map 200 is restored.

[0101] 5-2-2. Processing example In step S310 (see FIG. 13), the vehicle control system 10 downloads the thinned map 200D for the required area.

[0102] 20 is a flowchart showing step S310 in the case of the second method. In step S311, the vehicle control system 10 downloads the divided unsprung displacement maps 200D-1 to 200D-N of the required areas one by one in order. Each of the downloaded divided unsprung displacement maps 200D-j corresponds to the thinned map 200D. In step S312, the vehicle control system 10 holds a combination of the downloaded divided unsprung displacement maps 200D-j.

[0103] In step S320, the vehicle control system 10 performs an interpolation process on the combination of the downloaded divided unsprung displacement maps 200D-j. The method of the interpolation process may be the one shown in FIG. 16 or the one shown in FIG. 17.

[0104] 21 shows the interpolation process in a state where only two divided unsprung displacement maps 200D-1 and 200D-2 have been downloaded. The vehicle control system 10 performs the interpolation process on the combination of the downloaded divided unsprung displacement maps 200D-1 and 200D-2. More specifically, the vehicle control system 10 interpolates at least a part of the thinned-out portion DEC along the vehicle traveling direction X. That is, the vehicle control system 10 interpolates the thinned-out portion DEC sandwiched between the original portions ORG in the vehicle traveling direction X by using the data of the original portions ORG.

[0105] After a certain amount of time has passed, all of the divided unsprung displacement maps 200D-1 to 200D-N for the required areas are available. However, there is a possibility that communication will be interrupted along the way. When communication is interrupted, a situation may arise in which only a portion of the divided unsprung displacement maps 200D-1 to 200D-N is downloaded. Even in that case, by performing the interpolation process as described above, it is possible to continue vehicle control without significantly impairing the accuracy of vehicle control. In other words, it is possible to improve robustness against communication interruption while ensuring vehicle control accuracy.

[0106] Preferably, the vehicle control system 10 downloads the divided unsprung displacement maps 200D-1 to 200D-N of a fairly wide area, not just the vicinity of the vehicle 1, one by one in sequence. The larger the area, the greater the total amount of data in the unsprung displacement map 200. However, by downloading the divided unsprung displacement maps 200D-1 to 200D-N one by one, the communication bandwidth required per unit time can be reduced. Even if communication is interrupted during downloading, vehicle control can be continued as described above. If the divided unsprung displacement maps 200D-j of a fairly wide area are acquired, vehicle control can be continued for a longer period of time even if communication is interrupted. In other words, the continuity of vehicle control is further improved.

[0107] 5-3. The third method A combination of the first and second methods is also possible. [Explanation of symbols]

[0108] 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 200D Thinned Map 200D-1~200D-3 Split unsprung displacement map DEC Thinning part INT Interpolated data ORG Original part M unit area X Vehicle travel direction Y Horizontal

Claims

1. A vehicle control method for controlling a vehicle based on a parameter map that represents a correspondence relationship between a parameter related to vertical movement of a wheel and a position, comprising: a process of communicating with a map management system that manages an original parameter map, and downloading a thinned map in which a part of data in a vehicle traveling direction is thinned out from the original parameter map as a thinned out portion, wherein the thinned map has an original portion other than the thinned out portion that is the same as the original parameter map, a process of acquiring the parameters of a target position while interpolating, along the vehicle traveling direction, at least a part of a thinned-out portion sandwiched between the original portions in the thinned-out map in the vehicle traveling direction using data of the original portions sandwiching the thinned-out portion; controlling the vehicle based on the parameters of the target position; Includes A vehicle control method.

2. 2. A vehicle control method according to claim 1, The thinned map is obtained by periodically thinning out a part of the data in the vehicle travel direction from the original parameter map as the thinned part. A vehicle control method.

3. 3. A vehicle control method according to claim 1, further comprising: The amount of data in the thinned portion that is thinned out from the original parameter map increases as the speed of the vehicle increases. A vehicle control method.

4. 2. A vehicle control method according to claim 1, the original parameter map is composed of a combination of a plurality of divided parameter maps; each of the plurality of divided parameter maps corresponds to a thinned map in which at least a portion of data in the vehicle traveling direction is thinned out as the thinned portion from the original parameter map; The process of downloading the thinning map includes a process of downloading the plurality of division parameter maps one by one in sequence. A vehicle control method.

5. A vehicle control method according to any one of claims 1 to 4, The process of interpolating at least a part of the thinned portion includes: - estimating a future trajectory of the wheels of the vehicle; a process of interpolating the thinned-out portion on the estimated trajectory along the vehicle traveling direction using data of the original portion that sandwiches the thinned-out portion; Includes A vehicle control method.

6. A vehicle control method according to any one of claims 1 to 4, The process of interpolating at least a part of the thinned-out portion includes a process of entirely interpolating the thinned-out portion along the vehicle travel direction using data of the original portion that sandwiches the thinned-out portion. A vehicle control method.

7. A vehicle control method according to any one of claims 1 to 6, comprising: the target position is a predicted passing position of a wheel of the vehicle; The process of controlling the vehicle includes a process of controlling an actuator to suppress vibration of the vehicle based on the parameter of the predicted passing position. A vehicle control method.

8. A vehicle control system that controls a vehicle based on a parameter map that represents a correspondence relationship between a parameter related to vertical movement of a wheel and a position, One or more processors; The one or more processors: a process of communicating with a map management system that manages an original parameter map, and downloading a thinned map in which a part of data in a vehicle traveling direction is thinned out from the original parameter map as a thinned out portion, wherein the thinned map has an original portion other than the thinned out portion that is the same as the original parameter map, a process of acquiring the parameters of a target position while interpolating, along the vehicle traveling direction, at least a part of a thinned-out portion sandwiched between the original portions in the thinned-out map in the vehicle traveling direction using data of the original portions sandwiching the thinned-out portion; controlling the vehicle based on the parameters of the target position; configured to run Vehicle control system.

Images