JP2023047040A - Map management method and map management system - Google Patents

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

The present disclosure relates to technology for managing a parameter map that represents correspondence between parameters and positions related to vertical movement of wheels.

Patent Literature 1 discloses a road surface displacement map representing the correspondence relationship between road surface displacement (road surface unevenness) and positions. Damping control is performed by using such a road surface displacement map. Specifically, the road surface displacement at a predetermined position in front of the vehicle is recognized in advance from the road surface displacement map. A control amount of the active suspension is calculated in advance according to the road surface displacement recognized in advance. By controlling the active suspension at the timing when the wheel passes through the predetermined position, the vibration of the vehicle is effectively suppressed.

U.S. Patent Application Publication No. 2018/0154723

Consider a parameter map that represents the correspondence between parameters and positions related to the up-and-down motion of the wheel. Such a parameter map is used for vehicle control such as damping control as disclosed in Patent Document 1, for example.

The inventor of the present application paid attention to the following points. That is, the road surface (road surface condition, unevenness of the road surface) may change due to factors such as road construction, aging, and the like. When the road surface changes, it is desirable to efficiently reflect the road surface change in the parameter map. This is because, if the road surface change is not reflected in the parameter map, the accuracy of vehicle control using the parameter map may decrease.

One object of the present disclosure is to provide a technique that can appropriately respond to changes in the road surface with respect to a parameter map representing the correspondence relationship between parameters and positions related to vertical movement of wheels.

A first aspect relates to a map management method for managing a parameter map that represents the correspondence between parameters and positions related to the up-and-down motion of wheels.
Map management method
A process of acquiring map update information, which is information obtained while the vehicle is running and is necessary for updating the parameter map;
Map update processing for updating the parameter map based on the latest map update information and the past map update information for the same position.
In the map update process, the degree of contribution of the latest map update information relating to a specific position where the degree of road surface change from the previous time exceeds a threshold is made higher than the contribution of the latest map update information relating to normal positions other than the specific position. Including processing.

A second aspect relates to map management systems.
map management system
one or more processors;
one or more storage devices for storing a parameter map representing correspondence between parameters and positions related to vertical movement of the wheels.
The one or more processors are
A process of acquiring map update information, which is information obtained while the vehicle is running and is necessary for updating the parameter map;
map update processing for updating the parameter map based on the latest map update information and the past map update information with respect to the same position.
In the map update process, the degree of contribution of the latest map update information relating to a specific position where the degree of road surface change from the previous time exceeds a threshold is made higher than the contribution of the latest map update information relating to normal positions other than the specific position. Including processing.

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

1 is a schematic diagram showing a configuration example of a vehicle according to an embodiment; FIG. 1 is a conceptual diagram showing a configuration example of a suspension according to an embodiment; FIG. It is a flow chart which shows an example of unsprung displacement calculation processing concerning an embodiment. 1 is a block diagram showing a configuration example of a vehicle control system according to an embodiment; FIG. 4 is a block diagram showing an example of driving environment information according to the embodiment; FIG. 1 is a block diagram showing a configuration example of a map management system according to an embodiment; FIG. It is a conceptual diagram for explaining an unsprung displacement map according to the embodiment. It is a conceptual diagram which shows an example of the unsprung displacement map which concerns on embodiment. FIG. 4 is a conceptual diagram for explaining the relationship between the sampling result of vertical motion parameters by a sensor and the vehicle speed; It is a conceptual diagram showing another example of the unsprung displacement map according to the embodiment. FIG. 7 is a conceptual diagram showing still another example of an unsprung displacement map according to the embodiment; FIG. 5 is a conceptual diagram for explaining preview control using an unsprung displacement map according to the embodiment; 7 is a flowchart showing preview control using an unsprung mass displacement map according to the embodiment; 4 is a flowchart for explaining an outline of a map management method by the map management system according to the embodiment; 4 is a flowchart showing an example of map update processing (step S200) according to the embodiment; 7 is a flowchart showing an example of road surface change acquisition processing (step S210) according to the embodiment;

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

1. Suspension and Vertical Motion Parameters FIG. 1 is a schematic diagram showing a configuration example of a vehicle 1 according to the present embodiment. A vehicle 1 has 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, right front wheel 2FR, left rear wheel 2RL, and right rear wheel 2RR, respectively. In the following description, each wheel will be called a wheel 2 and each suspension will be called a suspension 3 unless there is a particular need to distinguish them.

FIG. 2 is a conceptual diagram showing a configuration example of the suspension 3. As shown in FIG. Suspension 3 is provided to connect between unsprung structure 4 and sprung structure 5 of vehicle 1 . The unsprung structure 4 includes wheels 2 . The suspension 3 includes springs 3S, dampers (shock absorbers) 3D, and actuators 3A. The spring 3S, damper 3D, and actuator 3A are provided in parallel between the unsprung structure 4 and the sprung structure 5. As shown in FIG. A spring constant of the spring 3S is K. The damping coefficient of damper 3D is C. The damping force of damper 3D may be variable. The actuator 3</b>A applies a vertical control force Fc between the unsprung structure 4 and the sprung structure 5 .

Here, we define the terms. "Road surface displacement Zr" is the vertical displacement of the road surface RS. The “unsprung displacement Zu” is the vertical displacement of the unsprung structure 4 . The “sprung displacement Zs” is the vertical displacement of the sprung structure 5 . The “unsprung speed Zu′” is the vertical speed of the unsprung structure 4 . The “sprung speed Zs′” is the vertical speed of the sprung structure 5 . The “unsprung acceleration Zu″” is the vertical acceleration of the unsprung structure 4 . The “sprung acceleration Zs″” is the vertical acceleration of the sprung structure 5 . The sign of each parameter is positive for upward and negative for downward.

The wheels 2 move on the road surface RS. In the following description, parameters related to the vertical motion of the wheels 2 are called "vertical motion parameters". The vertical motion parameters include the road surface displacement Zr, the unsprung displacement Zu, the unsprung velocity Zu', the unsprung acceleration Zu'', the sprung displacement Zs, the sprung velocity Zs', the sprung acceleration Zs'', and the like. exemplified. The vertical motion parameter can also be said to be a "road surface displacement related parameter" related to the road surface displacement Zr.

As an example, the following description considers the case where the vertical motion parameter is the unsprung displacement Zu. For generalization, "unsprung displacement" in the following description should be read as "vertical motion parameter".

FIG. 3 is a flowchart showing an example of unsprung displacement calculation processing.

In step S<b>11 , the sprung acceleration Zs″ is detected by the sprung acceleration sensor 22 installed on the sprung structure 5 . In step S12, the sprung displacement Zs is calculated by second-order integration of the sprung acceleration Zs''.

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, stroke ST is detected by a stroke sensor installed on 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.

In step S14, filtering processing is performed on the time-series data of the sprung mass displacement Zs in order to suppress the influence of sensor drift and the like. Similarly, in step S15, filtering processing is performed on the time-series data of the stroke ST. For example, the filter is a bandpass 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 0.3-10 Hz.

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

Instead of steps S14 and S15, filtering processing may be performed on the time-series data of the unsprung displacement Zu calculated in step S16.

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

2. Vehicle control system 2-1. Configuration Example FIG. 4 is a block diagram showing a configuration example of the vehicle control system 10 according to the present embodiment. A vehicle control system 10 is mounted on the 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 traveling device 60, and a control device .

Vehicle state sensor 20 detects the state of 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. Vehicle state sensor 20 may include stroke sensor 23 that detects stroke ST. Vehicle state sensor 20 may include an unsprung acceleration sensor. In addition, the vehicle state sensor 20 includes a lateral acceleration sensor, a yaw rate sensor, a steering angle sensor, and the like.

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

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

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

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

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 necessary for processing by the processor 71 . Examples of the storage device 72 include volatile memory, nonvolatile memory, HDD (Hard Disk Drive), SSD (Solid State Drive), and the like. The control device 70 may include one or more ECUs (Electronic Control Units).

Vehicle control program 80 is a computer program for controlling vehicle 1 and is executed by processor 71 . A vehicle control program 80 is stored in the storage device 72 . Alternatively, vehicle control program 80 may be recorded on a computer-readable recording medium. The functions of the control device 70 are implemented by the processor 71 executing the vehicle control program 80 .

2-2. Driving Environment Information FIG. 5 is a block diagram showing an example of driving environment information 90 indicating the driving environment of the vehicle 1 . Driving environment information 90 is stored in storage device 72 . The driving environment information 90 includes map information 91 , vehicle state information 92 , surrounding situation information 93 and position information 94 .

Map information 91 includes a general navigation map. The map information 91 may indicate lane layout, road shape, and the like. The map information 91 may include position information such as white lines, traffic lights, signs, landmarks, and the like. Map information 91 is obtained from a map database. The map database may be installed in the vehicle 1 or stored in an external management server. In the latter case, the control device 70 communicates with the management server and acquires the necessary map information 91 .

The map information 91 further includes an "unsprung displacement map 200". Details of the unsprung displacement map 200 will be described later.

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

The surrounding situation information 93 is information indicating the surrounding situation of the vehicle 1 . The control device 70 recognizes the surrounding conditions of the vehicle 1 using the recognition sensor 30 and acquires the surrounding condition 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.

The surrounding situation information 93 further includes “object information” regarding objects around the vehicle 1 . Objects include pedestrians, bicycles, other vehicles (leading vehicles, parked vehicles, etc.), road structure (white lines, curbs, guardrails, walls, median strips, roadside structures, etc.), signs, poles, obstacles, etc. are exemplified. The object information indicates relative positions and relative velocities of objects with respect to the vehicle 1 . For example, by analyzing image information obtained by a camera, an object can be identified and the relative position of the object can be calculated. Also, based on the point cloud information obtained by LIDAR, an object can be identified and the relative position and relative velocity of the object can be obtained.

The position information 94 is information indicating the position and orientation of the vehicle 1 . The control device 70 acquires the position information 94 from the detection result by the position sensor 40 . Further, the control device 70 may acquire highly accurate position information 94 by well-known self-position estimation processing (localization) using object information and map information 91 .

2-3. The vehicle control control device 70 executes vehicle travel control for controlling travel of the vehicle 1 . Vehicle travel control includes steering control, drive control, and braking control. The control device 70 executes vehicle travel control by controlling the traveling device 60 (the steering device 61, the driving device 62, and the braking device 63). The control device 70 may perform driving support control to support driving of the vehicle 1 based on the driving environment information 90 . Examples of driving support control include lane keeping control, collision avoidance control, automatic driving control, and the like.

Furthermore, the control device 70 controls the suspension 3 . Typically, the control device 70 performs damping control that controls the suspension 3 to suppress vibration of the vehicle 1 . For example, the control device 70 controls the actuator 3A to generate a vertical control force Fc between the unsprung structure 4 and the sprung structure 5 (see FIG. 2). As another example, the control device 70 may variably control the damping force of the damper 3D. Damping control includes "preview control" to be described later.

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

Map management system 100 includes communication device 110 . A communication device 110 is connected to a communication network NET. For example, the communication device 110 communicates with many vehicles 1 via the communication network NET.

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). Processor 120 executes various types of information processing. For example, processor 120 includes a CPU. The storage device 130 stores various map information. The storage device 130 also stores various information necessary for processing by the processor 120 . Examples of the storage device 130 include volatile memory, nonvolatile memory, HDD, SSD, and the like.

Map management program 140 is a computer program for map management and is executed by processor 120 . A map management program 140 is stored in the storage device 130 . Alternatively, map management program 140 may be recorded on a computer-readable recording medium. The functions of the map management system 100 are implemented by the processor 120 executing the map management program 140 .

Processor 120 communicates with vehicle control system 10 of vehicle 1 via communication device 110 . The processor 120 collects various types of information from the vehicle control system 10, and generates and updates map information based on the collected information. Processor 120 also delivers map information to vehicle control system 10 . Processor 120 also provides map information in response to requests from vehicle control system 10 .

3-2. Unsprung Displacement Map One piece of map information managed by the map management system 100 is an "unsprung displacement map (vertical motion parameter map) 200". The unsprung displacement map 200 is a map relating to the unsprung displacement Zu (vertical motion parameter). The unsprung displacement map 200 is stored in the storage device 130 .

FIG. 7 is a conceptual diagram for explaining the unsprung displacement map 200. FIG. For example, an absolute coordinate system in the horizontal plane is defined by latitude and longitude directions, and a position is defined by latitude LAT and longitude LON. The unsprung displacement map 200 represents at least the correspondence relationship between the position (LAT, LON) and the unsprung displacement Zu. In other words, the unsprung displacement map 200 represents the unsprung displacement Zu at least as a function of position (LAT, LON).

The road area may be divided into meshes on the horizontal plane. That is, the road area may be divided into a plurality of unit areas M on the 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 relationship between the position of the unit area M and the unsprung displacement Zu. The position of the unit area M may be defined by the representative position (eg, center position) of the unit area M, or 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. As the unit area M is made smaller, the resolution of the unsprung displacement map 200 is increased.

Processor 120 collects information from multiple vehicles 1 via communication device 110 . The processor 120 then generates and updates the unsprung displacement map 200 based on information collected from many vehicles 1 .

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

3-2-1. First example (first unsprung displacement map)
A position in the unsprung displacement map 200 is a position through which the wheel 2 has passed. The position of each wheel 2 is calculated based on the position information 94 described above. Specifically, the relative positional relationship between the reference point of the vehicle position in the vehicle 1 and each wheel 2 is known information. Based on the relative positional relationship and the vehicle position indicated by the position information 94, the position of each wheel 2 can be calculated.

The unsprung displacement Zu is calculated by the method shown in FIG. That is, by using the vehicle state sensor 20 mounted on the vehicle 1, the sprung displacement Zs and the stroke ST can be obtained. These sprung displacement Zs and stroke ST are called "sensor base information" for convenience. The unsprung displacement Zu is calculated based on this sensor base information. Here, as described above, filtering processing is performed on the sensor base information or the time-series data of the unsprung displacement Zu in order to suppress the influence of sensor drift and the like.

For example, while the vehicle 1 is running, 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, the zero-phase filter cannot be used due to processing time constraints. A filter (online filter) that can be used by the control device 70 in real time is hereinafter referred to as a "first filter". The control device 70 performs a "first filtering process" that applies a first filter 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 "first unsprung displacement Zu1". As for the time-series data of the first unsprung mass displacement Zu1, a "phase shift" occurs due to the first filtering process using the first filter. Specifically, the high-pass filter causes "phase lead" and the low-pass filter causes "phase delay".

The control device 70 of the vehicle control system 10 associates the position of the wheel 2 at the same timing with the first unsprung displacement Zu1. The control device 70 then 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 . Based on the information received from the vehicle control system 10, the processor 120 of the map management system 100 generates the unsprung displacement map 200 representing the correspondence relationship between the position and the first unsprung displacement Zu1. The unsprung displacement map 200 representing the correspondence relationship between the position and the first unsprung displacement Zu1 is hereinafter referred to as the "first unsprung displacement map 210". The first unsprung displacement map 210 can be said to be the unsprung displacement map 200 generated through a first filtering process using a first filter.

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

3-2-2. Second example (second unsprung displacement map)
When performing filtering processing in the map management system 100, a zero-phase filter can be used because there is no restriction on processing time. By using a zero-phase filter, "out of phase" can be prevented. Filtering processing that applies a zero-phase filter to the sensor-based information or the time-series data of the unsprung displacement Zu is hereinafter referred to as “second filtering processing”. The unsprung displacement Zu calculated through the second filtering process is hereinafter referred to as "second unsprung displacement Zu2". The unsprung displacement map 200 representing the correspondence relationship between the position and the second unsprung displacement Zu2 is hereinafter referred to as the "second unsprung displacement map 220". The second unsprung displacement map 220 can be said to be the unsprung displacement map 200 generated through a second filtering process with a zero-phase filter.

The control device 70 of the vehicle control system 10 associates the position of the wheel 2 at the same timing with the sensor-based information or the unsprung displacement Zu (before filtering). Then, the control device 70 transmits a set of time-series data of the position of the wheel 2 and sensor-based information or time-series data of the unsprung displacement Zu (before filtering) to the map management system 100 . The processor 120 of the map management system 100 performs a second filtering process of applying a second filter to the sensor-based information or the time-series data of the unsprung displacement Zu. Through such a second filtering process, the second unsprung displacement Zu2 is calculated. The processor 120 generates a second unsprung displacement map 220 based on the positions of the wheels 2 and the second unsprung displacement Zu2.

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

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 .

3-2-3. Third example (unsprung displacement map considering vehicle speed)
FIG. 9 is a conceptual diagram for explaining the relationship between the sampling result of the vertical motion parameter by the sensor and the vehicle speed V. As shown in FIG. The horizontal axis represents the position on the route passed by the wheel 2 . The vertical axis represents the road surface displacement Zr as an example of the vertical motion parameter. Even if the wheels 2 pass exactly the same route, the sampling result by the sensor changes according to the vehicle speed V. Specifically, when the vehicle is traveling at a low speed, fine unevenness of the road surface RS is detected (extracted). That is, data with a short wavelength and a high spatial frequency are detected during low-speed running. On the other hand, when the vehicle is traveling at high speed, fine unevenness of the road surface RS is not detected (extracted). That is, when the vehicle is running at high speed, data with a long wavelength and a low spatial frequency is detected, and data with a short wavelength and a high spatial frequency is difficult to detect. Thus, the vehicle speed V and the detectable spatial frequency are inversely proportional.

Therefore, in the third example, the unsprung displacement map 200 is generated in consideration of the vehicle speed V as well. Specifically, the control device 70 of the vehicle control system 10 associates the position of the wheel 2 with the vehicle speed V when passing the position, and transmits a 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 an unsprung displacement map 200 based on the position and vehicle speed V. FIG. That is, the unsprung displacement map 200 represents the correspondence relationship between the position, the vehicle speed V, and the unsprung displacement Zu.

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 relationship 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 the unsprung displacement map 200 used when the vehicle speed V belongs to the first vehicle speed range. Unsprung displacement map 200-2 is unsprung displacement map 200 used when vehicle speed V belongs to a second vehicle speed range different from the first vehicle speed range.

FIG. 11 shows another example of the unsprung displacement map 200 according to the third example. In the example shown in FIG. 11, the position is the position of the unit area M (see FIG. 7). The unsprung displacement map 200 represents 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. FIG.

3-2-4. Fourth Example A combination of the above first or second example with the third example is also possible. 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.

3-3. Modification The vehicle control system 10 of the vehicle 1 may hold a database of the unsprung displacement map 200 and manage the unsprung displacement map 200 itself. That is, the map management system 100 may be included in the vehicle control system 10. FIG. The unsprung displacement map 200 in this case is, for example, the first unsprung displacement map 210 described above.

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 the unsprung displacement map 200 of the 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, based on the unsprung mass displacement map 200, the control device 70 executes "preview control," which is a type of damping control.

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. FIG.

In step S<b>31 , the control device 70 acquires the current position P<b>0 of each wheel 2 . The relative positional relationship between the vehicle position reference point of the vehicle 1 and each wheel 2 is known information. Based on the relative positional relationship and the vehicle position indicated by the position information 94, the position of each wheel 2 can be calculated.

In step S32, the control device 70 calculates the predicted passing position Pf of the wheel 2 after the preview time tp. The preview time tp is set, for example, to be longer than the time required for calculation processing and communication processing required until the actuator 3A of the suspension 3 is actuated. The preview time tp may be fixed or 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 ahead of the current position P0 by the preview distance Lp. As a modification, the control device 70 may calculate the predicted travel route based on the vehicle speed V and the steering angle of the wheels 2, and calculate the predicted passing position Pf based on the predicted travel route.

In step S<b>33 , the control device 70 reads 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 "phase shift" as a reference map, and uses the second unsprung displacement Zu2 at the predicted passing position Pf as a reference map. 2 Read from unsprung displacement map 220 .

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

An equation of motion for the sprung structure 5 (see FIG. 2) is represented by the following equation (1).

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 generated by the actuator 3A. Fc. If the vibration of the sprung structure 5 is completely canceled by the control force Fc (Zs''=0, Zs'=0, Zs=0), the control force Fc is expressed by the following equation (2). be.

A control force Fc that provides at least a damping effect is represented by the following equation (3).

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

The control device 70 calculates the target control force Fc_t according to the above formula (3) or (4). That is, the control device 70 substitutes the unsprung displacement Zu (second unsprung displacement Zu2) at the predicted passing position Pf into the equation (3) or (4) to calculate the target control force Fc_t.

In step S35, the control device 70 controls the actuator 3A so as to generate the target control force Fc_t at the timing when the wheel 2 passes through the predicted passing position Pf. The timing at which the wheels 2 pass the predicted passing position Pf can be known from the preview time tp.

The preview control using the unsprung mass displacement map 200 described above makes it possible to effectively suppress the vibration of the vehicle 1 (the sprung structure 5). In particular, by using the phase-free second unsprung displacement Zu2 obtained from the second unsprung displacement map 220, it is possible to accurately generate the target control force Fc_t required for damping at the predicted passing position Pf. That is, the accuracy of preview control is improved.

5. Response to changes in the road surface The road surface (road surface condition, unevenness of the road surface) 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 deteriorate. For example, if the preview control is performed based on the old unsprung mass displacement map 200 even though there is a significant change in the road surface, there is a possibility that the expected damping effect cannot be obtained. In the worst case, body vibration will increase.

Therefore, the present disclosure further proposes a technique capable of appropriately coping with road surface changes. In particular, the map management method by the map management system 100 will be described below. Note that 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 .

5-1. Outline of Map Management Method FIG. 14 is a flow chart for explaining an outline of a map management method by the map management system 100 .

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 running, and 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 (eg, sprung displacement Zs, stroke ST) necessary for calculating the unsprung displacement Zu. Alternatively, the map update information may include time-series data of 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 .

In step S200, the map management system 100 executes a "map update process" for updating the unsprung displacement map 200 based on the map update information. It should be noted that the unsprung displacement map 200 can be any of the various implementations described in Section 3-2 above.

According to the present embodiment, the map management system 100 holds map update information obtained in the past, and performs map update processing in consideration of the past map update information. That is, the map management system 100 updates the unsprung displacement map 200 based on the latest (current) map update information and past map update information for the same position. 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 times of map update information including the latest map update information. Here, N is an integer of 1 or more.

Further, according to the present embodiment, the "contribution degree" of each piece of map update information in map update processing is not constant, but is set variably for each position. Here, the degree of contribution means the degree to which each map update information contributes to the unsprung displacement Zu calculated by the map update process. In other words, the degree of contribution means the influence of each map update information on the unsprung displacement Zu calculated by the map update process. With respect to a certain position, if the contribution of the latest map update information increases, the contribution of past map update information relatively decreases. Conversely, if the contribution of the latest map update information decreases, the contribution of past map update information relatively increases.

More specifically, the map management system 100 sets the degree of contribution of each piece of map update information in the map update process for each position, taking road surface changes into account. The degree (magnitude) of the road surface change since the last map update is hereinafter referred to as "road surface change degree ΔRS". A road surface variation ΔRS can be defined for each position. A specific example of the method of acquiring the road surface variation ΔRS will be described later. A position where the road surface change degree ΔRS exceeds the threshold TH is hereinafter referred to as a “specific position PS”. On the other hand, a position where the road surface change degree ΔRS is equal to or less than the threshold TH, that is, a position other than the specific position PS is hereinafter referred to as a "normal position PN". The map management system 100 sets the contribution of the latest map update information regarding the specific position PS higher than the contribution of the latest map update information regarding the normal position PN. In other words, the map management system 100 makes the contribution of the past map update information regarding the specific position PS lower than the contribution of the past map update information regarding the normal position PN.

In this way, with regard to the specific position PS having a large road surface change degree ΔRS, the contribution of the latest map update information increases, and the contribution of past map update information decreases. Therefore, the map data (unsprung displacement Zu) of the specific position PS where the road surface variation ΔRS is large is quickly refreshed. In other words, road surface changes are efficiently reflected in the unsprung displacement map 200 . As a result, deterioration in accuracy of vehicle control such as preview control using the unsprung mass displacement map 200 is suppressed. That is, according to this embodiment, it is possible to appropriately cope with changes in the road surface.

5-2. Specific Example of Map Update Processing (Step S200) FIG. 15 is a flowchart showing an example of the map update processing (step S200).

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" for acquiring a road surface change degree ΔRS representing the degree (magnitude) of the road surface change from the previous time.

FIG. 16 is a flow chart showing an example of the road surface change acquisition process (step S210).

In step S211, the map management system 100 acquires the unsprung displacement Zu of the wheel position from the latest (current) map update information. For convenience, the unsprung displacement Zu obtained from the latest map update information will be referred to as "detected unsprung displacement Zu_d" or "detected parameter".

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 (that is, the unsprung displacement map 200 before update). The unsprung displacement Zu obtained from the existing unsprung displacement map 200 is called "reference unsprung displacement Zu_ref" or "reference parameter" for convenience.

In step S213, the map management system 100 calculates the road surface change degree ΔRS at the position based on the difference between the detected unsprung displacement Zu_d and the reference unsprung displacement Zu_ref at the same position. As the difference between the detected unsprung displacement Zu_d and the reference unsprung displacement Zu_ref increases, the road surface variation 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.

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

As an example, consider the 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 by the second filtering process. Therefore, it is preferable that the detected unsprung displacement Zu_d is also the second unsprung displacement Zu2 calculated by the second filtering process.

As another example, consider the case where the unsprung displacement map 200 is the first unsprung displacement map 210 generated through the 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 by the first filtering process. Therefore, the detected unsprung displacement Zu_d is also preferably the first unsprung displacement Zu1 calculated by the first filtering process.

In order to improve the accuracy of the road surface variation 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 step S212 described above, the map management system 100 acquires information on the vehicle speed V from the latest (current) map update information. Further, 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 . Accordingly, since the effective frequency band of the detected unsprung displacement Zu_d and the reference unsprung displacement Zu_ref match, the accuracy of the road surface variation ΔRS is improved.

As a modification of the road surface change acquisition process (step S210), the road surface change degree ΔRS may be calculated based on the surrounding situation information 93. FIG. For example, the surrounding situation information 93 includes point cloud information obtained by LIDAR. Based on the point group information, the degree of change from the previous time of the road surface displacement Zr at each position may be calculated. As another example, the surrounding situation information 93 includes image information captured by a camera. By analyzing the image information, significant road surface changes may be detected.

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, other vehicles, or the like.

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

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

When the map update information for the normal position PN is obtained for the first time, the first number of travels N1 is "1". If the map update information for the same normal position PN has been obtained in the past, the first number N1 of travels is 2 or more. However, a first upper limit value MAX1 is provided for the first number of times of travel N1. That is, the first number N1 of travels 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".

Since the first upper limit value MAX1 is provided, the degree of contribution of the latest map update information is ensured to some extent. As a result, changes in the road surface over time are appropriately reflected in the unsprung displacement map 200 .

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

A second upper limit value MAX2 is provided for the second number of times of travel N2. That is, the second number of times of travel N2 is an integer that does not exceed the second upper limit value MAX2. The second upper limit value MAX2 is smaller than the first upper limit value MAX1 described above.

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. As a result, the map data of the specific position PS are refreshed the earliest.

However, there is a possibility that an erroneous determination of the road surface variation ΔRS may occur. If an erroneous determination of the road surface change degree ΔRS occurs and the second upper limit value MAX2 is "1", the unsprung displacement map 200 is overwritten with an erroneous unsprung displacement Zu. That is, the unsprung displacement map 200 is erroneously refreshed completely.

Therefore, as another example, the second upper limit value MAX2 may be intentionally set to 2 or more. In this case, the above 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, not only the latest map update information but also past map update information still have some influence. Therefore, even if an erroneous determination of the road surface variation ΔRS occurs, the unsprung displacement map 200 is prevented from being completely refreshed. In other words, it is possible to achieve both the refresh speed and the erroneous determination resistance.

As a modified example of the second map update process (step S240), the latest map update information may be regarded as multiple map update information instead of one map update information. In this case, the second upper limit value MAX2 may be the same as the first upper limit value MAX1.

In any example, the second map update process for the specific position PS increases the contribution of the latest map update information, compared to the first map update process for the normal position PN. This reduces the contribution of user information. Therefore, the map data of the specific position PS are quickly refreshed. In other words, road surface changes are efficiently reflected in the unsprung displacement map 200 .

5-2-5. Step S250
In step S<b>250 , the map management system 100 turns on the “road surface change flag” for the unsprung displacement Zu at the specific position PS in the unsprung displacement map 200 .

5-3. Vehicle Control When performing vehicle control using the unsprung displacement map 200 , the vehicle control system 10 acquires the unsprung displacement Zu at the target position from the unsprung displacement map 200 . For example, in the case of the preview control described above, the target position is the predicted passing position Pf of the wheel 2 after the preview time tp (see FIGS. 12 and 13).

When 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 lowers gains α and β (see formulas (3) and (4)) in preview control than usual. In addition, a low-pass filter may be applied to the unsprung displacement Zu in order to remove high-frequency components that are susceptible to road surface changes. The vehicle control system 10 may set the gain of well-known damping control based on feedback control larger than usual.

5-4. Effect As described above, according to the present embodiment, the unsprung displacement map 200 is updated for the same position based on the latest map update information and past map update information. Regarding the specific position PS with a large road surface change degree ΔRS, the contribution of the latest map update information increases, and the contribution of past map update information decreases. Therefore, the map data (unsprung displacement Zu) of the specific position PS where the road surface variation ΔRS is large is quickly refreshed. In other words, road surface changes are efficiently reflected in the unsprung displacement map 200 . As a result, deterioration in accuracy of vehicle control such as preview control using the unsprung mass displacement map 200 is suppressed. That is, according to this embodiment, it is possible to appropriately cope with changes in the road surface.

Suppressing a decrease in accuracy of vehicle control means that unnecessary vehicle control is not performed. Since unnecessary vehicle control is not performed, energy consumption is suppressed. In addition, durability of parts is improved. Furthermore, heat generation of parts such as the actuator 3A and the processor 71 is also suppressed.

1 vehicle 2 wheel 3 suspension 3A actuator 10 vehicle control system 20 vehicle state sensor 30 recognition sensor 40 position sensor 50 communication device 60 travel device 70 control device 80 vehicle control program 90 driving environment information 93 surrounding situation information 94 position information 100 map management system 110 communication device 120 processor 130 storage device 140 map management program 200 unsprung displacement map 210 first unsprung displacement map 220 second unsprung displacement map Zu unsprung displacement Zu_d detected unsprung displacement Zu_ref reference unsprung displacement ΔRS road surface variation

Claims (9)

A map management method for managing a parameter map representing a correspondence relationship between a parameter and a position related to vertical movement of a wheel,
a process of acquiring map update information, which is information obtained while the vehicle is running and is necessary for updating the parameter map;
map update processing for updating the parameter map based on the latest map update information and past map update information for the same position,
In the map update process, the degree of contribution of the latest map update information relating to a specific position where the degree of road surface change from the previous time exceeds a threshold is calculated as the contribution of the latest map update information relating to normal positions other than the specific position. A map management method that includes processing to be higher than. The map management method according to claim 1,
The map update process includes a first map update process of updating the parameter map based on the map update information of the first number of times of travel 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 that does not exceed the first upper limit,
The map management method, wherein the first upper limit value is 2 or more. The map management method according to claim 2,
The map update process includes a second map update process of updating the parameter map based on map update information for a second number of runs including the latest map update information for the specific position,
The second number of times of running is an integer that does not exceed the second upper limit,
Said 2nd upper limit is smaller than said 1st upper limit. Map management method. The map management method according to claim 3,
The map management method, wherein the second upper limit value is 2 or more. The map management method according to any one of claims 1 to 4,
The map update process further includes a road surface change acquisition process of acquiring the degree of change of the road surface from the previous time. The map management method according to claim 5,
The road surface change acquisition process includes:
A process of acquiring the latest parameter from the latest map update information as a detection parameter;
A process of acquiring the parameter at the same position as the detected parameter from the parameter map as a reference parameter;
A map management method, comprising calculating the degree of change based on a difference between the detected parameter and the reference parameter. The map management method according to claim 6,
The map management method, wherein the detection parameters and the reference parameters are calculated through the same filtering process. The map management method according to claim 6 or 7,
the parameter map represents a correspondence relationship between the parameter, the position, and the vehicle speed;
The map management method, wherein the process of acquiring the reference parameter includes a process of acquiring the reference parameter corresponding to the vehicle speed of the vehicle from the parameter map. one or more processors;
one or more storage devices that store a parameter map representing the correspondence relationship between parameters and positions related to vertical movement of the wheels,
The one or more processors are
a process of acquiring map update information, which is information obtained while the vehicle is running and is necessary for updating the parameter map;
map update processing for updating the parameter map based on the latest map update information and past map update information for the same position,
In the map update process, the degree of contribution of the latest map update information relating to a specific position where the degree of road surface change from the previous time exceeds a threshold is calculated as the contribution of the latest map update information relating to normal positions other than the specific position. A map management system that includes processing to make it higher than.

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