Vehicle Control System

Abstract

To effectively perform vibration damping control applied to a vehicle. [Solution] A vehicle control system applied to a target vehicle controls actuators to perform vibration suppression control that suppresses vibration of a sprung structure on a target wheel. A map indicates the correspondence between vertical movement parameters related to the vertical movement of the wheel and position. The vibration suppression control includes preview control that uses vertical movement parameters obtained from the map and non-map-dependent control that uses vertical movement parameters calculated based on measurement results from sensors mounted on the target vehicle. The total gain is the sum of a first gain for the preview control and a second gain for the non-map-dependent control. The ideal gain is a total gain that minimizes vibration of the sprung structure and is predetermined. The first gain and second gain are set so that the total gain does not exceed twice the ideal gain.

Description

[Technical Field]

[0001] The present disclosure relates to vibration damping control applied to a vehicle, and more particularly to vibration damping control using a map indicating a correspondence relationship between a parameter related to the vertical movement of a wheel and a position. [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 vibration suppression control applied to a vehicle. One example of vibration suppression control is preview control, which uses a map that indicates the correspondence between parameters related to the vertical movement of the wheels and their positions. Preview control has high control performance, but there may be situations in which the reliability of preview control temporarily decreases. For example, if the road surface conditions change due to road construction or the like and the map becomes outdated, the reliability of preview control using the outdated map is not necessarily high.

[0005] One object of the present disclosure is to provide a technology that can effectively perform vibration damping control applied to a vehicle. [Means for solving the problem]

[0006] One aspect of the present disclosure relates to a vehicle control system applied to a target vehicle. The target vehicle is equipped with an actuator that applies a vertical control force to the suspension of the target wheel. The vehicle control system one or more processors that control the actuators to execute vibration suppression control to suppress vibration of the sprung structure on the target wheel; one or more storage devices that store a map showing the correspondence between vertical movement parameters related to the vertical movement of the wheels and positions; Equipped with. Vibration control is preview control using up-down movement parameters obtained from the map; Map-independent control that uses vertical movement parameters calculated based on the measurement results from sensors installed on the target vehicle. Includes: The total gain is the sum of the first gain for preview control and the second gain for non-map dependent control. The ideal gain is a total gain that minimizes vibration of the sprung structure, and is determined in advance. The one or more processors are configured to set the first gain and the second gain such that the total gain is no more than twice the ideal gain. [Effects of the Invention]

[0007] According to the present disclosure, the vibration damping control applied to the target vehicle is a combination of preview control and non-map-dependent control. The preview control uses vertical movement parameters obtained from a map, while the non-map-dependent control uses vertical movement parameters calculated based on measurement results by a sensor. Therefore, in a scene where the reliability of the vertical movement parameters obtained from the map is low and the reliability of the preview control is low, a vibration damping effect can be obtained by the non-map-dependent control.

[0008] Furthermore, according to the present disclosure, the total gain, which is the sum of the first gain for preview control and the second gain for non-map-dependent control, is also appropriately set. Specifically, the total gain is set so as not to exceed twice the ideal gain that minimizes vibration. If the total gain were to exceed twice the ideal gain, there is a risk that vibrations would increase (excitation) compared to when vibration suppression control is not applied. According to the present disclosure, the total gain is set so as not to exceed twice the ideal gain, making it possible to reliably obtain vibration suppression effects without incurring vibration. [Brief explanation of the drawings]

[0009] [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] 10 is a flowchart showing an outline of a map generation / update process according to an embodiment. [Figure 9] FIG. 10 is a conceptual diagram for explaining preview control using an unsprung displacement map according to the embodiment. [Figure 10] 10 is a flowchart illustrating preview control using an unsprung displacement map according to an embodiment. [Figure 11] 10A and 10B are conceptual diagrams for explaining an example of a method for calculating the reliability of preview control according to the embodiment. [Figure 12] 5A and 5B are conceptual diagrams for explaining rear preview control according to the embodiment. [Figure 13] FIG. 4 is a conceptual diagram for explaining setting of a total gain of vibration damping control according to the embodiment. [Figure 14] 10A and 10B are conceptual diagrams for explaining an example of gain setting taking into consideration the reliability of preview control according to the embodiment. [Figure 15] 10A and 10B are conceptual diagrams for explaining another example of gain setting taking into consideration the reliability of preview control according to the embodiment. [Figure 16] FIG. 10 is a conceptual diagram for explaining yet another example of gain setting taking into consideration the reliability of preview control according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[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 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.

[0012] 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 (acts) a vertical control force Fc 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 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.

[0015] 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."

[0016] FIG. 3 is a flowchart showing 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 acceleration Zs'' is double-integrated to calculate the sprung displacement Zs.

[0018] 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.

[0019] 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.

[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 applied to a vehicle 1 and controls the vehicle 1. For example, the vehicle control system 10 is mounted on the vehicle 1. As another example, the vehicle control system 10 may be distributed between the vehicle 1 and a remote device. The vehicle control system 10 includes a vehicle state sensor 20, a recognition sensor 30, a position sensor 40, a communication device 50, a driving device 60, and a control device 70.

[0024] The vehicle state sensor 20 is mounted on the vehicle 1 and detects the state of the vehicle 1. The vehicle state sensor 20 includes a vehicle speed sensor (wheel speed sensor) 21 that detects the vehicle speed V of the vehicle 1, a sprung acceleration sensor 22 that detects the sprung acceleration Zs'', and the like. The vehicle state sensor 20 may also include a stroke sensor 23 that detects the stroke ST. The vehicle state sensor 20 may also include an unsprung acceleration sensor. In addition, the vehicle state sensor 20 includes a lateral acceleration sensor, a yaw rate sensor, a steering angle sensor, and the like.

[0025] The recognition sensor 30 is mounted on the vehicle 1 and recognizes (detects) the situation around the vehicle 1. Examples of the recognition sensor include a camera, a LIDAR (Laser Imaging Detection and Ranging), and a radar.

[0026] The position sensor 40 is mounted on the vehicle 1 and includes a positioning device that detects the position and orientation of the vehicle 1. For example, the position sensor 40 includes a Global Navigation Satellite System (GNSS). For example, the position sensor 40 includes an RTK-GNSS.

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

[0028] The traveling device 60 includes a steering device 61, a drive device 62, a braking device 63, and a suspension 3 (see FIG. 2) mounted on the vehicle 1. The steering device 61 steers the wheels 2. For example, the steering device 61 includes an electric power steering (EPS) device. The drive device 62 is a power source that generates a driving force. Examples of the drive device 62 include an engine, an electric motor, and an in-wheel motor. The braking device 63 generates a braking force.

[0029] The control device 70 is a computer that controls the vehicle 1. The control device 70 may be mounted on the vehicle 1, or may be partially included in a remote device. The control device 70 includes one or more processors 71 (hereinafter simply referred to as processor 71) and one or more storage devices 72 (hereinafter simply referred to as storage devices 72). The processor 71 executes various processes. For example, the processor 71 includes a CPU (Central Processing Unit). The processor 71 can also be called a processing circuitry. The storage device 72 stores various information required for processing by the processor 71. Examples of the storage device 72 include a volatile memory, a non-volatile memory, an HDD (Hard Disk Drive), an SSD (Solid State Drive), etc. The control device 70 may include one or more ECUs (Electronic Control Units).

[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 on a computer-readable recording medium. The processor 71 executes the vehicle control program 80, thereby realizing 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 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.

[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 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.

[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 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.

[0035] 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.

[0036] 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.

[0037] The position information 94 is information indicating the position and orientation of the vehicle 1. The position includes a horizontal position and a vertical position. For example, the horizontal position is defined by latitude and longitude. The vertical position is defined by altitude (elevation). Examples of altitude include sea level, geoid height, and ellipsoid height. The control device 70 acquires the position information 94 based on the measurement results of a position sensor 40 such as a GNSS. As another example, the control device 70 may acquire the position information 94 by dead reckoning. As yet another example, the control device 70 may acquire highly accurate position information 94 by a well-known self-position estimation process (localization) that uses object information and map information 91.

[0038] 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.

[0039] 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 sprung structure 5 of the vehicle 1 (target vehicle). 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), thereby suppressing vibration of the sprung structure 5. 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.

[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, 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.

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

[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 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.

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

[0046] FIG. 7 is a conceptual diagram for explaining the unsprung displacement map 200. The XY plane represents a horizontal plane. For example, the absolute coordinate system on the horizontal plane is defined by the latitude and longitude directions, and the horizontal position is defined by the latitude and longitude. The unsprung displacement map 200 represents the correspondence between at least the horizontal position (X, Y) and the unsprung displacement Zu. In other words, the unsprung displacement map 200 represents the unsprung displacement Zu as a function of at least the horizontal position (X, Y).

[0047] The road area may be divided into a mesh pattern on a horizontal plane. That is, the road area may be divided into a plurality of unit areas M on a horizontal plane. The unit area M is, for example, a square. The length of one side of the square is, for example, 10 cm. The unsprung displacement map 200 represents the correspondence between the position of the unit area M and the unsprung displacement Zu. The position of the unit area M may be defined by a representative position of the unit area M (e.g., a central position), or may be defined by the range of the unit area M (latitude range, longitude range). The unsprung displacement Zu of the unit area M is, for example, the average value of the unsprung displacement Zu acquired within the unit area M. The smaller the unit area M is, the higher the resolution of the unsprung displacement map 200.

[0048] 3-3. Map generation / update processing The processor 120 collects information from a large number of vehicles 1 via the communication device 110. Then, the processor 120 generates and updates the unsprung displacement map 200 based on the information collected from the large number of vehicles 1. An example of the map generation / update process will be described in more detail below.

[0049] 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.

[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 referred to as "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 sensor-based information. The control device 70 also associates the wheel position and the unsprung displacement Zu at the same timing. The control device 70 then transmits a set of time-series data of the wheel position and time-series data of the unsprung displacement Zu to the map management system 100. The processor 120 of the map management system 100 generates and updates the unsprung displacement map 200 based on the time-series data of the wheel position and the time-series data of the unsprung displacement Zu.

[0052] As another example, the control device 70 of the vehicle control system 10 associates wheel positions with sensor-based information at the same time. Then, the control device 70 transmits a set of time-series data of the wheel positions and time-series data of the sensor-based information to the map management system 100. The processor 120 of the map management system 100 calculates the unsprung displacement Zu based on the received sensor-based information. Furthermore, the processor 120 generates and updates the unsprung displacement map 200 based on the time-series data of the wheel positions and the time-series data of the unsprung displacement Zu.

[0053] When calculating the unsprung displacement Zu in the map management system 100, there is no restriction on processing time, so filtering processing can be performed using a zero-phase filter. By using a zero-phase filter, it is possible to prevent "phase shift."

[0054] FIG. 8 is a flowchart showing an outline of 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 this 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, 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.

[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, based on the unsprung displacement Zu at the predicted passing position Pf, a target control force Fc_t of the actuator 3A of the suspension 3. The target control force Fc_t is calculated, for example, as follows.

[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 out 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 a vibration damping effect is expressed by the following equation (3).

[0069]

number

[0070] 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).

[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 determined from the preview time tp.

[0074] 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).

[0075] 5. Preview control reliability As described above, the preview control uses the unsprung displacement Zu obtained from the unsprung displacement map 200. For convenience, the unsprung displacement Zu obtained from the unsprung displacement map 200 is referred to as the "unsprung displacement Zu_map." If the accuracy of the unsprung displacement Zu_map obtained from the unsprung displacement map 200 is low, the accuracy of the preview control that uses it may also be reduced. Therefore, it is preferable to understand the unsprung displacement Zu_map, i.e., how reliable the preview control is. The reliability of the preview control is hereinafter referred to as "preview reliability R." An example of calculating the preview reliability R will be described below.

[0076] 5-1. Scenes where map reliability decreases The road surface (road surface condition, road surface unevenness) may change due to factors such as road construction, earthquakes, etc. If the road surface change is not reflected in the unsprung displacement map 200, the unsprung displacement Zu_map obtained from the unsprung displacement map 200 is not necessarily accurate. Therefore, it can be said that the preview reliability R is low in such a scene.

[0077] FIG. 11 is a conceptual diagram for explaining an example of a method for calculating preview reliability R. First, the vehicle control system 10 or the map management system 100 acquires the unsprung displacement Zu_map at a certain wheel position from the unsprung displacement map 200. Then, the vehicle control system 10 or the map management system 100 calculates the unsprung displacement Zu_sen at the same wheel position according to the method shown in FIG. 3. The unsprung displacement Zu_sen is calculated based on the measurement results from the on-board sensor and does not depend on the unsprung displacement map 200. Next, the vehicle control system 10 or the map management system 100 calculates the difference ΔZu (=|Zu_map-Zu_sen|) between the unsprung displacement Zu_map and the unsprung displacement Zu_sen at the same wheel position. Then, the vehicle control system 10 or the map management system 100 calculates the preview reliability R at that wheel position based on the difference ΔZu. Specifically, the smaller the difference ΔZu, the higher the preview reliability R. Conversely, the larger the difference ΔZu, the lower the preview reliability R becomes.

[0078] The calculation cycle of preview reliability R may be longer than the control cycle of preview control. For example, there is a certain distance of a section where the road surface has changed due to road construction, an earthquake, or the like. When vehicle 1 enters that section, preview reliability R decreases, and thereafter, the state in which preview reliability R is low continues for some time. Because the section with low preview reliability R continues for some time, the calculation cycle of preview reliability R may be longer than the control cycle of preview control.

[0079] In order to reduce the "phase shift" between the unsprung displacement Zu_map and the unsprung displacement Zu_sen, the unsprung displacement Zu_map and the unsprung displacement Zu_sen may be calculated through the same filtering process. For example, both the unsprung displacement Zu_map and the unsprung displacement Zu_sen may be calculated by a zero-phase filter in the map management system 100.

[0080] 5-2.Scenes where the reliability of location information decreases In the preview control, the position information 94 is used to acquire the position of the wheel 2. If the accuracy of the position information 94 is low, the accuracy of the position of the wheel 2 will also be low. If the accuracy of the position of the wheel 2 is low, there is a risk that the unsprung displacement Zu_map read from the unsprung displacement map 200 will deviate from the unsprung displacement Zu at the actual position of the wheel 2. Therefore, it can be said that the preview reliability R is low even in such a scene. Below, an example of a method for calculating the reliability of the position information 94, i.e., the preview reliability R, will be described.

[0081] The position information 94 is obtained based on the measurement results of the position sensor 40 mounted on the vehicle 1. The position information 94 includes the horizontal and vertical positions of the vehicle reference point of the vehicle 1. The horizontal position is defined by latitude and longitude. The vertical position is defined by altitude (elevation). Examples of altitude include sea level, geoid height, and ellipsoid height. The vehicle reference point is arbitrary. For example, the vehicle reference point may be the center point of the vehicle or the mounting position of the position sensor 40. A design value (default value) of the relative height of the vehicle reference point from the road surface is given as known information. Furthermore, the relative height of the vehicle reference point from the road surface may be corrected from the design value taking into account the stroke ST of the suspension 3, the inclination of the vehicle body (roll angle, pitch angle), tire deflection, etc. In either case, the relative height of the vehicle reference point from the road surface is obtained. The vehicle control system 10 or the map management system 100 calculates the altitude of the road surface at the horizontal position of the vehicle 1 based on the vertical position of the vehicle 1 included in the position information 94. The road surface altitude thus obtained based on the position information 94 will be referred to as the "sensor-based altitude Hsen" hereinafter.

[0082] Meanwhile, an "altitude map" showing the correspondence between the latitude, longitude, and altitude of the road surface (ground) is prepared in advance. For example, map data published by the Geospatial Information Authority of Japan may be used as the altitude map. The vehicle control system 10 or the map management system 100 reads the altitude of the road surface at the horizontal position of the vehicle 1 from the altitude map. The road surface altitude obtained from the altitude map in this way will be referred to hereinafter as the "map-based altitude Hmap."

[0083] The vehicle control system 10 or the map management system 100 calculates the altitude deviation ΔH (=|Hsen-Hmap|) between the sensor-based altitude Hsen and the map-based altitude Hmap. Then, the vehicle control system 10 or the map management system 100 calculates the preview reliability R based on the altitude deviation ΔH. Specifically, the smaller the altitude deviation ΔH, the higher the preview reliability R. Conversely, the larger the altitude deviation ΔH, the lower the preview reliability R.

[0084] 5-3.Vehicle speed The error in the position information 94 acquired using the position sensor 40 such as a GNSS receiver is likely to be large when the vehicle speed V is low. This is because when the vehicle speed V is low, it becomes difficult to determine the traveling direction of the vehicle 1. Therefore, the preview reliability R may be set lower as the vehicle speed V is lower.

[0085] 6. Combination of preview control and map-independent control Overview In the following description, for convenience, the target of control by the vehicle control system 10 (control device 70) will be referred to as the "target vehicle 1T." The target vehicle 1T is equipped with an actuator 3A that applies a vertical control force Fc to the suspension 3 of the target wheel (see FIG. 2). The control device 70 controls the actuator 3A to perform "vibration suppression control" that suppresses vibration of the sprung structure 5 on the target wheel.

[0086] One example of vibration suppression control is preview control that uses the unsprung displacement Zu_map obtained from the unsprung displacement map 200. Although the control performance of the preview control is high, as described in Section 5 above, there may be situations in which the preview reliability R of the preview control decreases. Therefore, according to this embodiment, to supplement the preview control, another vibration suppression control that does not use the unsprung displacement map 200 is performed together with the preview control. The other vibration suppression control that does not use the unsprung displacement map 200 will hereinafter be referred to as "non-map-dependent control." In other words, the vibration suppression control according to this embodiment is a combination of preview control and non-map-dependent control.

[0087] An example of non-map-dependent control is general feedback control. For example, unsprung feedback control is applied to suppress vibrations based on the unsprung displacement Zu_sen. The unsprung displacement Zu_sen is calculated in real time according to the method shown in FIG. 3 based on the measurement results from a sensor mounted on the target vehicle 1T. The unsprung feedback control uses the unsprung displacement Zu_sen calculated in real time, rather than the unsprung displacement Zu_map obtained from the unsprung displacement map 200. When the vibration suppression control is a combination of preview control and feedback control, the control force Fc is expressed, for example, by the following equation (5).

[0088]

number

[0089] The first term on the right-hand side of equation (5) represents the control force due to preview control. The preview gain Gpre is the gain of preview control and corresponds to "β·K" in equation (4) above. β takes a value between 0 and 1. K is the upper and lower spring constant of spring 3S of the suspension of the target wheel of target vehicle 1T. The second term on the right-hand side of equation (5) represents the control force due to feedback control. The feedback gain Gfb is the gain of feedback control.

[0090] Due to the effects of integral error and filtering processing, the control performance of feedback control is not as high as that of preview control. However, since the unsprung displacement Zu_sen calculated in real time is used instead of the unsprung displacement Zu_map obtained from the unsprung displacement map 200, it can be said that the reliability (certainty) of feedback control is always high. Therefore, even in situations where the preview reliability R of the preview control is low, the feedback control can achieve a certain degree of vibration suppression effect.

[0091] Another example of non-map-dependent control is "rear preview control." Rear preview control will be described with reference to FIG. 12. Here, the description will be given using the combination of the left front wheel 2FL and the left rear wheel 2RL, but the same applies to the combination of the right front wheel 2FR and the right rear wheel 2RR. In rear preview control, it is assumed that the left front wheel 2FL and the left rear wheel 2RL of the target vehicle 1T pass through the same position. First, at the timing tx when the left front wheel 2FL passes through a certain position Px, the unsprung displacement Zu_sen is calculated in real time using the method shown in FIG. 3. For convenience, this unsprung displacement Zu_sen will be referred to as the front wheel unsprung displacement Zu_f_sen. After a time L / V has elapsed from the timing tx, the left rear wheel 2RL passes through the same position Px. Here, L is the wheelbase between the left front wheel 2FL and the left rear wheel 2RL, and V is the vehicle speed of the target vehicle 1T. At timing tx+L / V, preview control for the left rear wheel 2RL is performed using the previously calculated front wheel unsprung displacement Zu_f_sen instead of the unsprung displacement Zu_map.

[0092] The rear preview control also does not use the unsprung displacement map 200 and is therefore not affected by the preview reliability R. When the vibration suppression control is a combination of the preview control and the rear preview control, the control force Fc is expressed by, for example, the following equation (6).

[0093]

number

[0094] As with the above equation (5), the first term on the right side of equation (6) represents the control force due to the preview control. Zu_r_map is the unsprung displacement Zu_map read out from the unsprung displacement map 200 for the preview control for the left rear wheel 2RL. The second term on the right side of equation (6) represents the control force due to the rear preview control. The rear preview gain Grp is the gain of the rear preview control. e -τs represents the time delay calculated from the wheelbase L and vehicle speed V.

[0095] By generalizing equations (5) and (6), the control force Fc when vibration suppression control is a combination of preview control and non-map-dependent control is expressed by the following equation (7).

[0096]

number

[0097] The first term on the right side of equation (7) represents the control force due to preview control. The first gain G1 is the preview gain Gpre described above. It can be said that the first gain G1 represents the contribution of preview control to the overall vibration suppression control. The unsprung displacement Zu_map is obtained from the unsprung displacement map 200. The second term on the right side of equation (7) represents the control force due to feedback control. The second gain G2 is the feedback gain Gfb in equation (5) or the rear preview gain Grp in equation (6). It can be said that the second gain G2 represents the contribution of non-map-dependent control to the overall vibration suppression control. The unsprung displacement Zu_sen is calculated in real time according to the method shown in Figure 3 based on the measurement results from sensors installed in the target vehicle 1T.

[0098] The control device 70 controls the actuator 3A according to the control force Fc obtained by equation (7) and performs vibration suppression control that is a combination of preview control and map-independent control. Therefore, even in a scene where the preview reliability R of the preview control is low, a vibration suppression effect can be obtained by map-independent control.

[0099] 6-2. Total gain setting The total gain Gt is the sum of the first gain G1 for preview control and the second gain G2 for non-map-dependent control (Gt = G1 + G2). If the total gain Gt is too large, there is a risk that vibrations will increase rather than be suppressed. To prevent such "vibration," it is necessary to set the total gain Gt appropriately.

[0100] FIG. 13 is a conceptual diagram for explaining the setting of the total gain Gt of vibration damping control according to this embodiment. The horizontal axis represents the total gain Gt, and the vertical axis represents the magnitude of vibration of the sprung structure 5. The ideal gain Gideal is the total gain Gt that minimizes the vibration of the sprung structure 5, and is determined in advance. As can be seen from the above equation (4), the ideal gain Gideal is, for example, K (Gideal=K). K is the upper and lower spring constants of the spring 3S of the suspension of the target wheel of the target vehicle 1T. Ideal gain information indicating the ideal gain Gideal is stored in advance in the storage device of the storage device 72 of the control device 70.

[0101] In FIG. 13, Gt=0 corresponds to the case where no vibration suppression control is performed. As the total gain Gt increases from 0, vibration is suppressed and reduced. When the total gain Gt reaches the ideal gain Gideal, vibration is minimized. When the total gain Gt becomes larger than the ideal gain Gideal, vibration occurs in the opposite direction to when vibration suppression control is not performed. However, as long as the total gain Gt does not exceed twice the ideal gain Gideal, even if vibration in the opposite direction occurs, the magnitude of the vibration itself will be smaller than when Gt=0. In other words, as long as the total gain Gt does not exceed twice the ideal gain Gideal, no vibration will occur and at least a vibration suppression effect will be obtained. When the total gain Gt becomes more than twice the ideal gain Gideal, vibration will occur.

[0102] As described above, according to this embodiment, the total gain Gt is set to be greater than 0 and not exceed twice the ideal gain Gideal. That is, the control device 70 sets the first gain G1 and the second gain G2 so that the total gain Gt is greater than 0 and not exceed twice the ideal gain Gideal. Preferably, the control device 70 sets the first gain G1 and the second gain G2 so that the total gain Gt is close to the ideal gain Gideal. Because the total gain Gt is set not to exceed twice the ideal gain Gideal, it is possible to reliably obtain a vibration damping effect without inducing vibration.

[0103] 6-3. Gain setting considering the reliability of preview control The control device 70 may flexibly adjust the respective contributions of the preview control and the map-non-dependent control according to the preview reliability R of the preview control. In other words, the control device 70 may flexibly adjust the ratio between the first gain G1 and the second gain G2 according to the preview reliability R of the preview control. Note that even if the ratio between the first gain G1 and the second gain G2 changes, the total gain Gt is still set as described in Section 6-2 above.

[0104] FIG. 14 is a conceptual diagram illustrating various examples of gain setting taking preview reliability R into consideration. The horizontal axis represents preview reliability R, and the vertical axis represents the first gain G1 of preview control. In example (A) of FIG. 14, the first gain G1 decreases monotonically as preview reliability R decreases. In example (B) of FIG. 14, the first gain G1 decreases stepwise as preview reliability R decreases. In example (C) of FIG. 14, preview control is performed when preview reliability R is equal to or greater than a threshold value Rth, and preview control is not performed when preview reliability R is less than the threshold value Rth (first gain G1=0). This can be generalized as follows: preview reliability R1 in the first state is higher than preview reliability R2 in the second state (R1>R2). The control device 70 sets the first gain G1 in the second state to be smaller than the first gain G1 in the first state. This makes it possible to prevent excessive preview control when preview reliability R is low. Moreover, when the preview reliability R is high, it becomes possible to effectively perform preview control.

[0105] FIG. 15 is a conceptual diagram illustrating another example of gain setting that takes preview reliability R into consideration. The horizontal axis represents preview reliability R, and the vertical axis represents the first gain G1 of preview control and the second gain G2 of map-non-dependent control. In example (A) of FIG. 15, as preview reliability R decreases, the first gain G1 monotonically decreases, and instead the second gain G2 monotonically increases. In example (B) of FIG. 15, as preview reliability R decreases, the first gain G1 decreases stepwise, and instead the second gain G2 monotonically increases. In example (C) of FIG. 15, preview control is executed when preview reliability R is equal to or greater than a threshold value Rth, and non-map-dependent control is executed instead of preview control when preview reliability R is less than the threshold value Rth. This can be generalized as follows: preview reliability R1 in the first state is higher than preview reliability R2 in the second state (R1>R2). The control device 70 makes the first gain G1 in the second state smaller than the first gain G1 in the first state. Also, the control device 70 makes the second gain G2 in the second state larger than the second gain G2 in the first state. This makes it possible to prevent excessive preview control from being performed when the preview reliability R is low, and to supplement the effect of vibration suppression control by map-non-dependent control.

[0106] The examples shown in Figures 14 and 15 can be generalized as follows: The ratio G1 / G2 is the ratio of the first gain G1 to the second gain G2. The preview reliability R1 in the first state is higher than the preview reliability R2 in the second state (R1>R2). The control device 70 sets the ratio G1 / G2 in the second state lower than the ratio G1 / G2 in the first state.

[0107] FIG. 16 is a conceptual diagram illustrating another example of gain setting that takes preview reliability R into consideration. The horizontal axis represents preview reliability R, and the vertical axis represents the first gain G1, the second gain G2, and the total gain Gt. In the example shown in FIG. 16, as preview reliability R decreases, the total gain Gt also decreases. For example, when preview reliability R is normally sufficiently high, the total gain Gt is set to the ideal gain Gideal. Then, as preview reliability R decreases, the first gain G1 and the total gain Gt decrease. At maximum arbitration when the first gain G1 is 0, the total gain Gt is half the ideal gain Gideal. This can be generalized as follows: Preview reliability R1 in the first state is higher than preview reliability R2 in the second state (R1>R2). The control device 70 sets the total gain Gt in the second state to be smaller than the total gain Gt in the first state. As a result, when the preview reliability R is low, it is possible to reduce the load on the actuator 3A and the power consumption while ensuring a certain degree of vibration suppression effect. [Explanation of symbols]

[0108] 1 vehicle 2 wheels 3. Suspension 10 Vehicle Control System 70 Control device 100 Map Management System 200 Unsprung Displacement Map

Claims

1. A vehicle control system applied to a target vehicle, the target vehicle includes an actuator that applies a vertical control force to a suspension of the target wheel; The vehicle control system includes: one or more processors that control the actuators to perform vibration damping control to suppress vibration of the sprung structure on the target wheel; one or more storage devices for storing a map showing the correspondence between vertical movement parameters related to the vertical movement of the wheels and positions; Equipped with The vibration damping control includes: a preview control that utilizes the vertical movement parameters obtained from the map; map-independent control that utilizes the vertical movement parameters calculated based on measurement results by sensors mounted on the target vehicle; Including, a total gain is the sum of a first gain for the preview control and a second gain for the non-map-dependent control; the ideal gain is the total gain that minimizes the vibration of the sprung structure, and is determined in advance; The one or more processors are configured to set the first gain and the second gain such that the total gain does not exceed twice the ideal gain. Vehicle control system.

2. 2. The vehicle control system according to claim 1, The reliability of the preview control in the first state is higher than the reliability of the preview control in the second state, a ratio is a ratio of the first gain to the second gain; The one or more processors are configured to make the ratio in the second state lower than the ratio in the first state. Vehicle control system.

3. 3. The vehicle control system according to claim 2, the one or more processors are configured to make the total gain in the second state smaller than the total gain in the first state. Vehicle control system.

4. 4. A vehicle control system according to claim 1, the vertical movement parameter is unsprung displacement, The ideal gain is equal to the upper and lower spring constants of the suspension of the target wheel. Vehicle control system.

5. 4. A vehicle control system according to claim 1, The non-map-dependent control is feedback control or rear preview control. Vehicle control system.

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