Map management method and map management system

Abstract

To provide a parameter map representing correspondence between parameters and positions relating to vertical movement of wheels, which can appropriately cope with changes in a road surface.SOLUTION: A parameter map represents correspondence between parameters and positions related to vertical movement of wheels. A map management method includes a process of acquiring map update information required for updating the parameter map, which is information obtained while a vehicle is running. The map management method further includes a map update process for updating the parameter map based on the latest map update information and the past map update information with respect to the same location. The map update process includes a process for making a degree of contribution of the latest map update information relating to a specific position where a degree of change in a road surface from the previous time exceeds a threshold value higher than the degree of contribution of the latest map update information relating to a normal position other than the specific position.SELECTED DRAWING: Figure 14

Description

[Technical Field]

[0001] The present disclosure relates to a technique for managing a parameter map that indicates the correspondence between parameters related to the up and down movement of a wheel and positions. [Background technology]

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

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

[0004] Consider a parameter map that represents the correspondence between parameters related to the vertical movement of a wheel and the position. Such a parameter map is used for vehicle control such as vibration damping control as disclosed in Patent Document 1, for example.

[0005] The inventors of the present application have focused on the following point: road surfaces (road surface conditions, road surface unevenness) may change due to factors such as road construction and changes over time. When the road surface changes, it is desirable to efficiently reflect the road surface changes in the parameter map. This is because if the road surface changes are not reflected in the parameter map, the accuracy of vehicle control using the parameter map may decrease.

[0006] One object of the present disclosure is to provide a technology that can appropriately respond to changes in road surface, regarding a parameter map that indicates the correspondence between parameters related to the up and down movement of a wheel and positions. [Means for solving the problem]

[0007] The first aspect relates to a map management method for managing a parameter map that indicates the correspondence between parameters related to the up and down movement of a wheel and positions. How to manage the map: A process of acquiring map update information necessary for updating the parameter map, the map update information being information obtained while the vehicle is traveling; A map update process for updating the parameter map based on the latest map update information and past map update information for the same position. Includes. The map update process includes a process of increasing the contribution of the latest map update information for a specific location where the degree of change in road surface since the previous time exceeds a threshold value, compared to the contribution of the latest map update information for a normal location other than the specific location.

[0008] The second aspect relates to map management systems. The map management system one or more processors; one or more storage devices for storing a parameter map that indicates the correspondence between parameters related to the up and down movement of the wheels and positions; Equipped with. The one or more processors A process of acquiring map update information necessary for updating the parameter map, the map update information being information obtained while the vehicle is traveling; A map update process for updating the parameter map based on the latest map update information and past map update information for the same position. is configured to execute The map update process includes a process of increasing the contribution of the latest map update information for a specific location where the degree of change in road surface since the previous time exceeds a threshold value, compared to the contribution of the latest map update information for a normal location other than the specific location. [Effects of the Invention]

[0009] According to the present disclosure, for the same position, a parameter map is updated based on the latest map update information and previous map update information. For a specific position where the degree of change in road surface is large, the contribution of the latest map update information increases and the contribution of the previous map update information decreases. Therefore, map data for the specific position where the degree of change in road surface is large is quickly refreshed. In other words, road surface changes are efficiently reflected in the parameter map. As a result, a decrease in the accuracy of vehicle control using the parameter map is suppressed. In this way, it is possible to appropriately respond to road surface changes. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram illustrating an example of the configuration of a vehicle according to an embodiment. [Figure 2] 1 is a conceptual diagram illustrating a configuration example of a suspension according to an embodiment. [Figure 3] 4 is a flowchart illustrating an example of an unsprung displacement calculation process according to the embodiment. [Figure 4] 1 is a block diagram showing an example of the configuration of a vehicle control system according to an embodiment; [Figure 5] 3 is a block diagram showing an example of driving environment information according to an embodiment; [Figure 6] 1 is a block diagram illustrating an example of the configuration of a map management system according to an embodiment. [Figure 7] FIG. 4 is a conceptual diagram for explaining an unsprung displacement map according to the embodiment. [Figure 8] FIG. 4 is a conceptual diagram illustrating an example of an unsprung displacement map according to the embodiment. [Figure 9]10 is a conceptual diagram for explaining the relationship between the sampling results of vertical movement parameters obtained by a sensor and vehicle speed. FIG. [Figure 10] FIG. 10 is a conceptual diagram showing another example of the unsprung displacement map according to the embodiment. [Figure 11] FIG. 10 is a conceptual diagram showing yet another example of the unsprung displacement map according to the embodiment. [Figure 12] FIG. 10 is a conceptual diagram for explaining preview control using an unsprung displacement map according to the embodiment. [Figure 13] 10 is a flowchart illustrating preview control using an unsprung displacement map according to an embodiment. [Figure 14] 1 is a flowchart for explaining an overview of a map management method by the map management system according to an embodiment. [Figure 15] 10 is a flowchart showing an example of a map update process (step S200) according to the embodiment. [Figure 16] 10 is a flowchart showing an example of a road surface change acquisition process (step S210) according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0012] 1. Suspension and vertical movement parameters FIG. 1 is a schematic diagram showing an example configuration of a vehicle 1 according to this embodiment. The vehicle 1 is equipped with wheels 2 and suspensions 3. The wheels 2 include a left front wheel 2FL, a right front wheel 2FR, a left rear wheel 2RL, and a right rear wheel 2RR. Suspensions 3FL, 3FR, 3RL, and 3RR are provided for the left front wheel 2FL, the right front wheel 2FR, the left rear wheel 2RL, and the right rear wheel 2RR, respectively. In the following description, unless a distinction is particularly required, each wheel will be referred to as a wheel 2, and each suspension will be referred to as a suspension 3.

[0013] FIG. 2 is a conceptual diagram showing an example configuration of a suspension 3. The suspension 3 is provided to connect the unsprung structure 4 and the sprung structure 5 of the vehicle 1. The unsprung structure 4 includes the wheel 2. The suspension 3 includes a spring 3S, a damper (shock absorber) 3D, and an actuator 3A. The spring 3S, the damper 3D, and the actuator 3A are provided in parallel between the unsprung structure 4 and the sprung structure 5. The spring 3S has a spring constant K. The damping coefficient of the damper 3D is C. The damping force of the damper 3D may be variable. The actuator 3A applies a vertical control force Fc between the unsprung structure 4 and the sprung structure 5.

[0014] 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.

[0015] The wheel 2 moves on the road surface RS. In the following description, parameters related to the vertical motion of the wheel 2 are referred to as "vertical motion parameters." Examples of vertical motion parameters include the above-mentioned road surface displacement Zr, unsprung displacement Zu, unsprung velocity Zu', unsprung acceleration Zu'', sprung displacement Zs, sprung velocity Zs', and sprung acceleration Zs''. The vertical motion parameters can also be said to be "road surface displacement-related parameters" related to the road surface displacement Zr.

[0016] As an example, in the following description, a case where the vertical movement parameter is the unsprung displacement Zu will be considered. To generalize, the term "unsprung displacement" in the following description should be read as "vertical movement parameter."

[0017] FIG. 3 is a flowchart showing an example of the unsprung displacement calculation process.

[0018] In step S11, the sprung acceleration Zs'' is detected by the sprung acceleration sensor 22 installed in the sprung structure 5. In step S12, the sprung acceleration Zs'' is double-integrated to calculate the sprung displacement Zs.

[0019] In step S13, the stroke ST (= Zs - Zu), which is the relative displacement between the sprung structure 5 and the unsprung structure 4, is acquired. For example, the stroke ST is detected by a stroke sensor installed in the suspension 3. As another example, the stroke ST may be estimated based on the sprung acceleration Zs'' by an observer configured based on a single wheel two-degree-of-freedom model.

[0020] In step S14, filtering is performed on the time series data of the sprung displacement Zs to suppress the effects of sensor drift, etc. Similarly, in step S15, filtering is performed on the time series data of the stroke ST. For example, the filter is a band-pass filter that passes signal components in a specific frequency band. The specific frequency band may be set to include the sprung resonance frequency of the vehicle 1. For example, the specific frequency band is 0.3 to 10 Hz.

[0021] In step S16, the difference between the sprung displacement Zs and the stroke ST is calculated as the unsprung displacement Zu.

[0022] 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.

[0023] 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''.

[0024] 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.

[0025] 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 the stroke ST. The vehicle state sensor 20 may also include an unsprung acceleration sensor. In addition, the vehicle state sensor 20 includes a lateral acceleration sensor, a yaw rate sensor, a steering angle sensor, and the like.

[0026] The recognition sensor 30 recognizes (detects) the situation around the vehicle 1. Examples of the recognition sensor include a camera, a LIDAR (Laser Imaging Detection and Ranging), and a radar.

[0027] 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).

[0028] The communication device 50 communicates with the outside of the vehicle 1 .

[0029] The traveling device 60 includes a steering device 61, a drive 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 drive device 62 is a power source that generates a driving force. Examples of the drive device 62 include an engine, an electric motor, and an in-wheel motor. The braking device 63 generates a braking force.

[0030] 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 processors 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), an SSD (Solid State Drive), etc. The control device 70 may include one or more ECUs (Electronic Control Units).

[0031] The vehicle control program 80 is a computer program for controlling the vehicle 1, and is executed by the processor 71. The vehicle control program 80 is stored in the storage device 72. Alternatively, the vehicle control program 80 may be recorded on a computer-readable recording medium. The processor 71 executes the vehicle control program 80, thereby realizing the functions of the control device 70.

[0032] 2-2. Driving environment information 5 is a block diagram showing an example of driving environment information 90 that indicates the driving environment of the vehicle 1. The driving environment information 90 is stored in the storage device 72. The driving environment information 90 includes map information 91, vehicle state information 92, surrounding situation information 93, and location information 94.

[0033] The map information 91 includes a general navigation map. The map information 91 may indicate lane layout, road shape, etc. The map information 91 may also include position information of white lines, traffic lights, signs, landmarks, etc. The map information 91 is obtained from a map database. The map database may be installed in the vehicle 1 or may be stored in an external management server. In the latter case, the control device 70 communicates with the management server to obtain the necessary map information 91.

[0034] The map information 91 further includes an "unsprung displacement map 200." The unsprung displacement map 200 will be described in detail later.

[0035] The vehicle state information 92 is information that indicates the state of the vehicle 1. The control device 70 acquires the vehicle state information 92 from the vehicle state sensor 20. For example, the vehicle state information 92 includes the vehicle speed V, the sprung acceleration Zs'', the stroke ST, the lateral acceleration, the yaw rate, the steering angle, and the like. The vehicle speed V may be calculated from the vehicle position detected by the position sensor 40. The control device 70 may calculate the unsprung displacement Zu by the method shown in FIG. 3. In this case, the vehicle state information 92 also includes the unsprung displacement Zu calculated by the control device 70.

[0036] The surrounding situation information 93 is information that indicates the situation around the vehicle 1. The control device 70 recognizes the situation around the vehicle 1 using the recognition sensor 30 and acquires the surrounding situation information 93. For example, the surrounding situation information 93 includes image information captured by a camera. As another example, the surrounding situation information 93 includes point cloud information obtained by LIDAR.

[0037] The surrounding situation information 93 further includes "object information" relating to objects around the vehicle 1. Examples of objects include pedestrians, bicycles, other vehicles (preceding vehicles, parked vehicles, etc.), road configurations (white lines, curbs, guardrails, walls, medians, roadside structures, etc.), signs, poles, obstacles, etc. The object information indicates the relative position and relative speed of the object with respect to the vehicle 1. For example, by analyzing image information obtained by a camera, it is possible to identify the object and calculate the relative position of the object. It is also possible to identify the object and obtain the relative position and relative speed of the object based on point cloud information obtained by LIDAR.

[0038] The position information 94 is information indicating the position and direction of the vehicle 1. The control device 70 acquires the position information 94 from the detection result by the position sensor 40. The control device 70 may also acquire highly accurate position information 94 by a well-known self-position estimation process (localization) that uses object information and map information 91.

[0039] 2-3.Vehicle control The control device 70 performs vehicle driving control to control the driving of the vehicle 1. The vehicle driving control includes steering control, drive control, and braking control. The control device 70 performs vehicle driving control by controlling the driving devices 60 (steering device 61, drive device 62, and braking device 63). The control device 70 may perform driving assistance control to assist the driving of the vehicle 1 based on the driving environment information 90. Examples of driving assistance control include lane keeping control, collision avoidance control, and automatic driving control.

[0040] Furthermore, the control device 70 controls the suspension 3. Typically, the control device 70 controls the suspension 3 to perform vibration suppression control that suppresses vibration of the vehicle 1. For example, the control device 70 controls the actuator 3A to generate a control force Fc in the vertical direction between the unsprung structure 4 and the sprung structure 5 (see FIG. 2). As another example, the control device 70 may variably control the damping force of the damper 3D. The vibration suppression control includes a "preview control" that will be described later.

[0041] 3. Map Management System 3-1.Configuration example 6 is a block diagram showing an example of the configuration of a map management system 100 according to this embodiment. The map management system 100 is a computer that manages various types of map information. The management of map information includes the generation, updating, provision, distribution, etc. of the map information. Typically, the map management system 100 is a management server on a cloud. The map management system 100 may be a distributed system in which multiple servers perform distributed processing.

[0042] The map management system 100 includes a communication device 110. The communication device 110 is connected to a communication network NET. For example, the communication device 110 communicates with a large number of vehicles 1 via the communication network NET.

[0043] The map management system 100 further includes one or more processors 120 (hereinafter simply referred to as processors 120) and one or more storage devices 130 (hereinafter simply referred to as storage devices 130). The processor 120 executes various types of information processing. For example, the processor 120 includes a CPU. The 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.

[0044] The map management program 140 is a computer program for map management, and is executed by the processor 120. The map management program 140 is stored in the storage device 130. Alternatively, the map management program 140 may be recorded on a computer-readable recording medium. The processor 120 executes the map management program 140 to implement the functions of the map management system 100.

[0045] 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.

[0046] 3-2.Unsprung displacement map One of the pieces of 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 relating to unsprung displacement Zu (vertical movement parameter). The unsprung displacement map 200 is stored in the storage device 130.

[0047] 7 is a conceptual diagram for explaining the unsprung displacement map 200. For example, an absolute coordinate system on 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 the correspondence between at least 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).

[0048] The road area may be divided into a mesh pattern on a horizontal plane. That is, the road area may be divided into a plurality of unit areas M on a horizontal plane. The unit area M has, for example, a rectangular shape. For example, the unit area M is a square with a side length 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 of the unit area M (e.g., a central position), or may be defined by the range of the unit area M (latitude range, longitude range). The unsprung displacement Zu of the unit area M is, for example, the average value of the unsprung displacement Zu acquired within the unit area M. The smaller the unit area M, the higher the resolution of the unsprung displacement map 200.

[0049] The processor 120 collects information from a large number of vehicles 1 via the communication device 110. Then, the processor 120 generates and updates the unsprung displacement map 200 based on the information collected from the large number of vehicles 1.

[0050] Various specific examples of the unsprung displacement map 200 will be described below.

[0051] 3-2-1. First example (first unsprung displacement map) The positions in the unsprung displacement map 200 are positions that the wheels 2 have passed through. The position of each wheel 2 is calculated based on the above-mentioned position information 94. Specifically, the relative positional relationship between the reference point of the vehicle position on the vehicle 1 and each wheel 2 is known information. Based on this relative positional relationship and the vehicle position indicated by the position information 94, the position of each wheel 2 can be calculated.

[0052] The unsprung displacement Zu is calculated by the method shown in FIG. 3. That is, the sprung displacement Zs and the stroke ST are obtained by using the vehicle state sensor 20 mounted on the vehicle 1. For convenience, the sprung displacement Zs and the stroke ST are referred to as "sensor-based information." The unsprung displacement Zu is calculated based on this sensor-based information. Here, as described above, in order to suppress the influence of sensor drift and the like, a filtering process is performed on the sensor-based information or the time-series data of the unsprung displacement Zu.

[0053] For example, while the vehicle 1 is traveling, the control device 70 of the vehicle control system 10 calculates the unsprung displacement Zu in real time. However, when calculating the unsprung displacement Zu in real time, a zero-phase filter cannot be used due to processing time constraints. A filter (online filter) that the control device 70 can use in real time is hereinafter referred to as the "first filter." The control device 70 performs a "first filtering process" in which the first filter is applied to the sensor-based information or the time-series data of the unsprung displacement Zu. The unsprung displacement Zu calculated through this first filtering process is hereinafter referred to as the "first unsprung displacement Zu1." With regard to the time-series data of the first unsprung displacement Zu1, a "phase shift" occurs due to the first filtering process using the first filter. Specifically, a "phase lead" occurs due to the high-pass filter, and a "phase lag" occurs due to the low-pass filter.

[0054] The control device 70 of the vehicle control system 10 associates the position of the wheel 2 with the first unsprung displacement Zu1 at the same time. Then, the control device 70 transmits a set of time-series data of the position of the wheel 2 and time-series data of the first unsprung displacement Zu1 to the map management system 100. The processor 120 of the map management system 100 generates an unsprung displacement map 200 that represents the correspondence between the position and the first unsprung displacement Zu1 based on the information received from the vehicle control system 10. The unsprung displacement map 200 that represents the correspondence between the position and the first unsprung displacement Zu1 will be referred to hereinafter as the "first unsprung displacement map 210." It can be said that the first unsprung displacement map 210 is the unsprung displacement map 200 that is generated through a first filtering process using a first filter.

[0055] The map management system 100 may perform the first filtering process instead of the vehicle control system 10. In this case, the control device 70 of the vehicle control system 10 associates the position of the wheel 2 with the sensor-based information or the unsprung displacement Zu (before filtering process) at the same time. Then, the control device 70 transmits a set of time-series data of the position of the wheel 2 and time-series data of the sensor-based information or the unsprung displacement Zu (before filtering process) to the map management system 100. The processor 120 of the map management system 100 performs a first filtering process that applies a first filter to the time-series data of the sensor-based information or the unsprung displacement Zu. After such first filtering process, the first unsprung displacement Zu1 is calculated. The processor 120 generates a first unsprung displacement map 210 based on the position of the wheel 2 and the first unsprung displacement Zu1.

[0056] 3-2-2. Second example (second unsprung displacement map) When performing filtering processing in the map management system 100, there are no processing time constraints, so a zero-phase filter can be used. Using a zero-phase filter can prevent "phase shift." The filtering processing in which a zero-phase filter is applied to the sensor-based information or the time-series data of the unsprung displacement Zu is hereinafter referred to as the "second filtering processing." The unsprung displacement Zu calculated through the second filtering processing is hereinafter referred to as the "second unsprung displacement Zu2." The unsprung displacement map 200 representing the correspondence between the position and the second unsprung displacement Zu2 is hereinafter referred to as the "second unsprung displacement map 220." It can be said that the second unsprung displacement map 220 is the unsprung displacement map 200 generated through the second filtering processing using a zero-phase filter.

[0057] The control device 70 of the vehicle control system 10 associates the position of the wheel 2 with the sensor-based information or the unsprung displacement Zu (before filtering processing) at the same time. Then, the control device 70 transmits a set of time-series data of the position of the wheel 2 and time-series data of the sensor-based information or the unsprung displacement Zu (before filtering processing) to the map management system 100. The processor 120 of the map management system 100 performs a second filtering process that applies a second filter to the time-series data of the sensor-based information or the unsprung displacement Zu. After this second filtering process, the second unsprung displacement Zu2 is calculated. The processor 120 generates a second unsprung displacement map 220 based on the position of the wheel 2 and the second unsprung displacement Zu2.

[0058] Fig. 8 is a conceptual diagram showing an example of the unsprung displacement map 200. In the example shown in Fig. 8, the unsprung displacement map 200 includes both a first unsprung displacement map 210 and a second unsprung displacement map 220. In this case, the first unsprung displacement map 210 and the second unsprung displacement map 220 are used depending on the application.

[0059] As another example, the unsprung displacement map 200 may include only one of the first unsprung displacement map 210 and the second unsprung displacement map 220.

[0060] 3-2-3. Third example (unsprung displacement map considering vehicle speed) FIG. 9 is a conceptual diagram illustrating the relationship between the sampling results of vertical movement parameters obtained by the sensor and vehicle speed V. The horizontal axis represents the position on the path traveled by the wheel 2. The vertical axis represents road surface displacement Zr as an example of a vertical movement parameter. Even if the wheel 2 travels the exact same path, the sampling results obtained by the sensor vary depending on the vehicle speed V. Specifically, when traveling at low speeds, small irregularities in the road surface RS are detected (extracted). In other words, when traveling at low speeds, data with short wavelengths and high spatial frequencies is detected. On the other hand, when traveling at high speeds, small irregularities in the road surface RS are not detected (extracted). In other words, when traveling at high speeds, data with long wavelengths and low spatial frequencies is detected, and data with short wavelengths and high spatial frequencies is difficult to detect. In this way, the vehicle speed V is inversely proportional to the detectable spatial frequency.

[0061] Therefore, in the third example, the unsprung displacement map 200 is generated taking into consideration the vehicle speed V. Specifically, the control device 70 of the vehicle control system 10 associates the position of the wheel 2 with the vehicle speed V when the wheel 2 passes through that position, and transmits the set of the position and the vehicle speed V to the map management system 100. The processor 120 of the map management system 100 generates the unsprung displacement map 200 based on the position and the vehicle speed V. That is, the unsprung displacement map 200 represents the correspondence between the position, the vehicle speed V, and the unsprung displacement Zu.

[0062] Fig. 10 shows an example of an unsprung displacement map 200 according to the third example. In the example shown in Fig. 10, the unsprung displacement map 200 represents the correspondence between the position and the unsprung displacement Zu for each vehicle speed range. In other words, a different unsprung displacement map 200 is prepared for each vehicle speed range. For example, the unsprung displacement map 200-1 is an unsprung displacement map 200 used when the vehicle speed V falls within a first vehicle speed range. The unsprung displacement map 200-2 is an unsprung displacement map 200 used when the vehicle speed V falls within a second vehicle speed range different from the first vehicle speed range.

[0063] Fig. 11 shows another example of the unsprung displacement map 200 according to the third example. In the example shown in Fig. 11, the positions are positions of the unit area M (see Fig. 7). The unsprung displacement map 200 shows the correspondence relationship between the vehicle speed V (or vehicle speed range) and the unsprung displacement Zu for each position of the unit area M.

[0064] 3-2-4. Fourth Example It is also possible to combine the first or second example with the third example. That is, the first unsprung displacement map 210 may represent the correspondence relationship between the position, the vehicle speed V, and the first unsprung displacement Zu1. Similarly, the second unsprung displacement map 220 may represent the correspondence relationship between the position, the vehicle speed V, and the second unsprung displacement Zu2.

[0065] 3-3. Modified Examples The vehicle control system 10 of the vehicle 1 may hold a database of the unsprung displacement map 200 and manage its own unsprung displacement map 200. In other words, the map management system 100 may be included in the vehicle control system 10. In this case, the unsprung displacement map 200 is, for example, the first unsprung displacement map 210 described above.

[0066] 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.

[0067] Fig. 12 is a conceptual diagram for explaining preview control. Fig. 13 is a flowchart showing preview control. Preview control will be described with reference to Figs. 12 and 13.

[0068] In step S31, the control device 70 acquires the current position P0 of each wheel 2. The relative positional relationship between the reference point of the vehicle position on the vehicle 1 and each wheel 2 is known information. Based on this relative positional relationship and the vehicle position indicated by the position information 94, the position of each wheel 2 can be calculated.

[0069] In step S32, the control device 70 calculates a predicted passing position Pf of the wheel 2 after the preview time tp. The preview time tp is set, for example, to be equal to or longer than the time required for calculation processing and communication processing required to operate the actuator 3A of the suspension 3. The preview time tp may be fixed or may be variable depending on the situation. The preview distance Lp is given by the product of the preview time tp and the vehicle speed V. The predicted passing position Pf is a position that is the preview distance Lp ahead of the current position P0. As a modified example, the control device 70 may calculate a predicted traveling route based on the vehicle speed V and the steering angle of the wheel 2, and calculate the predicted passing position Pf based on the predicted traveling route.

[0070] 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. Preferably, the control device 70 uses the second unsprung displacement map 220 (see Section 3-2-2) without a “phase shift” as a reference map, and reads out the second unsprung displacement Zu2 at the predicted passing position Pf from the second unsprung displacement map 220.

[0071] In step S34, the control device 70 calculates, based on the unsprung displacement Zu (second unsprung displacement Zu2) at the predicted passing position Pf, a target control force Fc_t of the actuator 3A of the suspension 3. The target control force Fc_t is calculated, for example, as follows.

[0072] The equation of motion for the sprung structure 5 (see FIG. 2) is expressed by the following equation (1).

[0073]

number

[0074] In equation (1), m is the mass of the sprung structure 5, C is the damping coefficient of the damper 3D, K is the spring constant of the spring 3S, and Fc is the vertical control force Fc generated by the actuator 3A. If the vibration of the sprung structure 5 is completely canceled out by the control force Fc (Zs''=0, Zs'=0, Zs=0), the control force Fc is expressed by the following equation (2).

[0075]

number

[0076] The control force Fc that provides at least a vibration damping effect is expressed by the following equation (3).

[0077]

number

[0078] In equation (3), gain α is greater than 0 and less than or equal to 1, and gain β is also greater than 0 and less than or equal to 1. When the differential term in equation (3) is omitted, the control force Fc that provides at least the vibration damping effect is expressed by the following equation (4).

[0079]

number

[0080] 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 (second unsprung displacement Zu2) at the predicted passing position Pf into formula (3) or formula (4).

[0081] In step S35, the control device 70 controls the actuator 3A to generate a target control force Fc_t at the timing when the wheel 2 passes through the predicted passing position Pf. The timing when the wheel 2 passes through the predicted passing position Pf can be determined from the preview time tp.

[0082] The preview control using the unsprung displacement map 200 described above makes it possible to effectively suppress vibrations of the vehicle 1 (sprung structure 5). In particular, by using the second unsprung displacement Zu2 without phase shift obtained from the second unsprung displacement map 220, it is possible to accurately generate the target control force Fc_t required for vibration suppression at the predicted passing position Pf. In other words, the accuracy of the preview control is improved.

[0083] 5. Response to changes in road surface The road surface (road surface condition, road surface unevenness) may change due to factors such as road construction and changes over time. When the road surface changes, it is desirable to efficiently reflect the road surface change in the unsprung displacement map 200. This is because if the road surface change is not reflected in the unsprung displacement map 200, the accuracy of vehicle control using the unsprung displacement map 200 may decrease. For example, if preview control is performed based on an old unsprung displacement map 200 even though there has been a significant change in the road surface, the expected vibration damping effect may not be obtained. In the worst case, body vibration may actually increase.

[0084] Therefore, the present disclosure further proposes a technology that can appropriately respond to changes in road surface. In the following, a map management method using the map management system 100 will be particularly described. The map management system 100 may be provided outside the vehicle 1 (see FIG. 6 ), or may be included in the vehicle control system 10 mounted on the vehicle 1.

[0085] 5-1. Overview of map management methods FIG. 14 is a flowchart for explaining an outline of the map management method by the map management system 100.

[0086] In step S100, the map management system 100 acquires "map update information" from the vehicle 1 (vehicle control system 10). The map update information is information obtained while the vehicle 1 is traveling, and includes time-series data on the position (wheel position) of the vehicle 1. The map update information also includes time-series data on 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 on the unsprung displacement Zu calculated by the vehicle control system 10. Furthermore, the map update information may include the vehicle speed V of the vehicle 1.

[0087] In step S200, the map management system 100 executes a "map update process" to update the unsprung displacement map 200 based on the map update information. Note that the unsprung displacement map 200 may be any of the various specific examples described in Section 3-2 above.

[0088] According to this embodiment, the map management system 100 holds map update information obtained in the past and performs map update processing taking the past map update information into consideration. That is, the map management system 100 updates the unsprung displacement map 200 for the same position based on the latest (current) map update information and the past map update information. For example, the unsprung displacement Zu at a certain position (unit area M) is the average value of the unsprung displacement Zu calculated from N pieces of map update information including the latest map update information. Here, N is an integer equal to or greater than 1.

[0089] Furthermore, according to this embodiment, the "contribution degree" of each piece of map update information in the map update process is not constant but is variably set for each position. Here, the contribution degree means the degree to which each piece of map update information contributes to the unsprung displacement Zu calculated by the map update process. In other words, the contribution degree means the influence of each piece of map update information on the unsprung displacement Zu calculated by the map update process. For a certain position, if the contribution degree of the latest map update information increases, the contribution degree of the previous map update information decreases relatively. Conversely, if the contribution degree of the latest map update information decreases, the contribution degree of the previous map update information increases relatively.

[0090] More specifically, the map management system 100 sets the contribution of each piece of map update information in the map update process for each location, taking road surface changes into consideration. The degree (magnitude) of road surface change since the previous map update is hereinafter referred to as the "road surface change degree ΔRS." The road surface change degree ΔRS can be defined for each location. A specific example of a method for acquiring the road surface change degree ΔRS will be described later. A location where the road surface change degree ΔRS exceeds the threshold value TH is hereinafter referred to as a "specific location PS." On the other hand, a location where the road surface change degree ΔRS is equal to or less than the threshold value TH, i.e., a location other than the specific location PS, is hereinafter referred to as a "normal location PN." The map management system 100 sets the contribution of the latest map update information for the specific location PS to be higher than the contribution of the latest map update information for the normal location PN. In other words, the map management system 100 sets the contribution of past map update information for the specific location PS to be lower than the contribution of past map update information for the normal location PN.

[0091] In this way, for a specific position PS where the road surface change rate ΔRS is large, the contribution of the latest map update information increases and the contribution of the past map update information decreases. Therefore, the map data (unsprung displacement Zu) for the specific position PS where the road surface change rate ΔRS is large is quickly refreshed. In other words, road surface changes are efficiently reflected in the unsprung displacement map 200. As a result, a decrease in the accuracy of vehicle control such as preview control using the unsprung displacement map 200 is suppressed. In other words, according to this embodiment, it is possible to appropriately respond to road surface changes.

[0092] 5-2. Specific example of map update process (step S200) FIG. 15 is a flowchart showing an example of the map update process (step S200).

[0093] 5-2-1. Step S210 (Road surface change acquisition process) In step S210, the map management system 100 performs a "road surface change acquisition process" to acquire a road surface change degree ΔRS that indicates the degree (magnitude) of change in the road surface since the previous time.

[0094] FIG. 16 is a flowchart showing an example of the road surface change acquisition process (step S210).

[0095] In step S211, the map management system 100 acquires the unsprung displacement Zu at the wheel position from the latest (current) map update information. For convenience, the unsprung displacement Zu obtained from the latest map update information is referred to as the "detected unsprung displacement Zu_d" or the "detection parameter."

[0096] In step S212, the map management system 100 acquires the unsprung displacement Zu at the same position as the detected unsprung displacement Zu_d from the existing unsprung displacement map 200 (i.e., the unsprung displacement map 200 before updating). For convenience, the unsprung displacement Zu acquired from the existing unsprung displacement map 200 is referred to as the "reference unsprung displacement Zu_ref" or "reference parameter."

[0097] In step S213, the map management system 100 calculates a road surface change degree ΔRS at a position based on the difference between the detected unsprung displacement Zu_d and the reference unsprung displacement Zu_ref at that position. As the difference between the detected unsprung displacement Zu_d and the reference unsprung displacement Zu_ref increases, the road surface change degree ΔRS increases. For example, the road surface change degree ΔRS is the absolute value of the difference between the detected unsprung displacement Zu_d and the reference unsprung displacement Zu_ref. As another example, the road surface change degree ΔRS may be the square of the difference between the detected unsprung displacement Zu_d and the reference unsprung displacement Zu_ref.

[0098] In order to improve the accuracy of the road surface change rate ΔRS, it is preferable to suppress the "phase shift" between the detected unsprung displacement Zu_d and the reference unsprung displacement Zu_ref. To achieve this, it is preferable that the detected unsprung displacement Zu_d and the reference unsprung displacement Zu_ref are calculated through the same filtering process.

[0099] As an example, consider a case where the unsprung displacement map 200 is a second unsprung displacement map 220 generated through a second filtering process using a zero-phase filter (see Section 3-2-2). The reference unsprung displacement Zu_ref read from the second unsprung displacement map 220 is the second unsprung displacement Zu2 calculated through the second filtering process. Therefore, it is preferable that the detected unsprung displacement Zu_d is also the second unsprung displacement Zu2 calculated through the second filtering process.

[0100] As another example, consider a case where the unsprung displacement map 200 is a first unsprung displacement map 210 generated through a first filtering process (see Section 3-2-1). The reference unsprung displacement Zu_ref read from the first unsprung displacement map 210 is the first unsprung displacement Zu1 calculated through the first filtering process. Therefore, it is preferable that the detected unsprung displacement Zu_d is also the first unsprung displacement Zu1 calculated through the first filtering process.

[0101] In order to improve the accuracy of the road surface change rate ΔRS, the vehicle speed V may be taken into consideration. Here, consider the case where the unsprung displacement map 200 represents the correspondence relationship between the position, the vehicle speed V, and the unsprung displacement Zu (see Section 3-2-3, FIGS. 10 and 11). In the above-mentioned step S212, the map management system 100 acquires information on the vehicle speed V from the latest (current) map update information. Furthermore, the map management system 100 acquires the reference unsprung displacement Zu_ref corresponding to the vehicle speed V from the existing unsprung displacement map 200. As a result, the effective frequency bands of the detected unsprung displacement Zu_d and the reference unsprung displacement Zu_ref match, thereby improving the accuracy of the road surface change rate ΔRS.

[0102] As a modified example of the road surface change acquisition process (step S210), the road surface change degree ΔRS may be calculated based on the surrounding condition information 93. For example, the surrounding condition information 93 includes point cloud information obtained by LIDAR. The degree of change in the road surface displacement Zr at each position from the previous time may be calculated based on the point cloud information. As another example, the surrounding condition information 93 includes image information captured by a camera. Significant road surface changes may be detected by analyzing the image information.

[0103] As another modification of the road surface change acquisition process (step S210), information on the road surface change degree ΔRS may be provided from a road management center, another vehicle, or the like.

[0104] 5-2-2. Step S220 In step S220, the map management system 100 compares the road surface change rate ΔRS with a threshold value TH for each position. If the road surface change rate ΔRS at a certain position is equal to or less than the threshold value TH (step S220; Yes), the position is a normal position PN, and the process proceeds to step S230. On the other hand, if the road surface change rate ΔRS at a certain position exceeds the threshold value TH (step S220; No), the position is a specific position PS, and the process proceeds to step S240.

[0105] 5-2-3. Step S230 (First map update process) In step S230, the map management system 100 performs a "first map update process" for the normal position PN. Specifically, for the normal position PN, the map management system 100 updates the unsprung displacement map 200 based on the map update information for the first number of times N1 of traveling. The map update information for the first number of times N1 of traveling includes at least the latest map update information.

[0106] When map update information for the normal position PN is obtained for the first time, the first travel count N1 is "1." When map update information for the same normal position PN has been obtained in the past, the first travel count N1 is 2 or more. However, a first upper limit value MAX1 is set for the first travel count N1. In other words, the first travel count N1 is an integer that does not exceed the first upper limit value MAX1. The first upper limit value MAX1 is 2 or more. For example, the first upper limit value MAX1 is "10."

[0107] Since the first upper limit value MAX1 is set, the contribution of the latest map update information is ensured to a certain extent, so that the unsprung displacement map 200 appropriately reflects the change over time of the road surface.

[0108] 5-2-4. Step S240 (Second map update process) In step S240, the map management system 100 performs a "second map update process" for the specific position PS. Specifically, for the specific position PS, the map management system 100 updates the unsprung displacement map 200 based on the map update information for the second number of times of traveling N2. The map update information for the second number of times of traveling N2 includes at least the latest map update information.

[0109] The second running count N2 is set to a second upper limit value MAX2. That is, the second running count N2 is an integer that does not exceed the second upper limit value MAX2. The second upper limit value MAX2 is smaller than the above-mentioned first upper limit value MAX1.

[0110] For example, the second upper limit value MAX2 is set to "1." In this case, the map management system 100 updates the unsprung displacement map 200 for the specific position PS based only on the latest map update information. This allows the map data for the specific position PS to be refreshed most quickly.

[0111] However, there is a possibility that the road surface change rate ΔRS may be erroneously determined. If the road surface change rate ΔRS is erroneously determined and the second upper limit value MAX2 is equal to 1, the unsprung displacement map 200 will be overwritten with the erroneous unsprung displacement Zu. In other words, the unsprung displacement map 200 will be erroneously completely refreshed.

[0112] Therefore, as another example, the second upper limit value MAX2 may be intentionally set to 2 or more. In this case, the above-mentioned first upper limit value MAX1 is 3 or more. For example, the first upper limit value MAX1 is 10, and the second upper limit value MAX2 is 5. When the second upper limit value MAX2 is 2 or more, the influence of not only the latest map update information but also past map update information remains to some extent. Therefore, even if an erroneous determination of the road surface change rate ΔRS occurs, the unsprung displacement map 200 is prevented from being completely refreshed. In other words, it is possible to achieve both a high refresh rate and resistance to erroneous determination.

[0113] As a modification of the second map update process (step S240), the latest map update information may be regarded as information for multiple map updates rather than information for a single map update. In this case, the second upper limit value MAX2 may be the same as the first upper limit value MAX1.

[0114] In either example, the second map update process for the specific position PS increases the contribution of the latest map update information and decreases the contribution of the older map update information compared to the first map update process for the normal position PN. Therefore, the map data for the specific position PS is quickly refreshed. In other words, road surface changes are efficiently reflected in the unsprung displacement map 200.

[0115] 5-2-5. Step S250 In step S250, the map management system 100 sets the "road surface change flag" for the unsprung displacement Zu at the specific position PS in the unsprung displacement map 200 to ON.

[0116] 5-3.Vehicle control When performing vehicle control using the unsprung displacement map 200, the vehicle control system 10 acquires the unsprung displacement Zu of the target position from the unsprung displacement map 200. 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 FIGS. 12 and 13).

[0117] If the target position is the specific position PS, the road surface change flag is ON. In this case, the vehicle control system 10 may weaken the vehicle control using the unsprung displacement map 200 more than usual. For example, the vehicle control system 10 may reduce the gains α and β (see equations (3) and (4)) in the preview control more than usual. Also, the vehicle control system 10 may apply a low-pass filter to the unsprung displacement Zu to remove high-frequency components that are easily affected by road surface changes. The vehicle control system 10 may set the gain of well-known vibration suppression control based on feedback control to be larger than usual.

[0118] Effects As described above, according to this embodiment, the unsprung displacement map 200 is updated for the same position based on the latest map update information and the previous map update information. For a specific position PS where the road surface change rate ΔRS is large, the contribution of the latest map update information increases and the contribution of the previous map update information decreases. Therefore, the map data (unsprung displacement Zu) for the specific position PS where the road surface change rate ΔRS is large is quickly refreshed. In other words, road surface changes are efficiently reflected in the unsprung displacement map 200. As a result, a decrease in the accuracy of vehicle control, such as preview control, using the unsprung displacement map 200 is suppressed. In other words, according to this embodiment, it is possible to appropriately respond to road surface changes.

[0119] Suppressing the deterioration of vehicle control accuracy means that unnecessary vehicle control is not performed. Since unnecessary vehicle control is not performed, energy consumption is suppressed. Furthermore, component durability is improved. Furthermore, heat generation from components such as the actuator 3A and the processor 71 is suppressed. [Explanation of symbols]

[0120] 1 vehicle 2 wheels 3. Suspension 3A Actuator 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 210 1st unsprung displacement map 220 Second unsprung displacement map Zu Unsprung displacement Zu_d Detected unsprung displacement Zu_ref Reference unsprung displacement ΔRS Road surface change

Claims

1. A map management method for managing 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 acquiring map update information, which is obtained while the vehicle is traveling and is necessary for updating the parameter map, the map update information including position information of the vehicle and information necessary for calculating the parameters; a map update process for calculating the parameters based on the latest map update information and past map update information for the same position and updating the parameter map; Including, the contribution degree of the latest map updating information is a degree to which the latest map updating information contributes to the parameter calculated by the map updating process, The map update process includes a process of making the contribution degree of the latest map update information for a specific position where a degree of change in road surface from the previous time exceeds a threshold higher than the contribution degree of the latest map update information for a normal position other than the specific position. How to manage maps.

2. 2. The map management method according to claim 1, further comprising: the map update process includes a first map update process for updating the parameter map based on map update information for a first traveling count including the latest map update information with respect to the normal position other than the specific position, The first number of times of running is an integer not exceeding a first upper limit value, The first upper limit is equal to or greater than 2. How to manage maps.

3. 3. The map management method according to claim 2, further comprising: the map update process includes a second map update process for updating the parameter map based on map update information for a second traveling count including the latest map update information with respect to the specific position, The second number of runs is an integer not exceeding a second upper limit value, The second upper limit value is smaller than the first upper limit value. How to manage maps.

4. 4. The map management method according to claim 3, further comprising: The second upper limit is 2 or more. How to manage maps.

5. 5. A map management method according to claim 1, further comprising the steps of: The map update process further includes a road surface change acquisition process for acquiring the degree of change of the road surface from the previous time. How to manage maps.

6. 6. A map management method according to claim 5, further comprising the steps of: The road surface change acquisition process includes: A process of acquiring the latest parameters as detection parameters from the latest map update information; A process of obtaining the parameter at the same position as the detection parameter from the parameter map as a reference parameter; calculating the degree of change based on a difference between the detection parameter and the reference parameter; Includes How to manage maps.

7. 7. A map management method according to claim 6, comprising: The detection parameters and the reference parameters are calculated through the same filtering process. How to manage maps.

8. 8. A map management method according to claim 6 or 7, comprising: the parameter map represents a correspondence relationship between the parameters, the position, and the vehicle speed; The process of acquiring the reference parameters includes a process of acquiring the reference parameters corresponding to the vehicle speed from the parameter map. How to manage maps.

9. one or more processors; one or more storage devices for storing a parameter map that indicates the correspondence between parameters related to the vertical movement of the wheels and positions; Equipped with The one or more processors: A process of acquiring map update information, which is obtained while the vehicle is traveling and is necessary for updating the parameter map, the map update information including position information of the vehicle and information necessary for calculating the parameters; a map update process for calculating the parameters based on the latest map update information and past map update information for the same position and updating the parameter map; configured to run the contribution degree of the latest map updating information is a degree to which the latest map updating information contributes to the parameter calculated by the map updating process, The map update process includes a process of making the contribution degree of the latest map update information for a specific position where a degree of change in road surface from the previous time exceeds a threshold higher than the contribution degree of the latest map update information for a normal position other than the specific position. Map management system.

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