Suspension control system

Abstract

To provide a suspension control system which can suppress occurrence of vibration and lateral force at a boundary between presence and absence of a road surface displacement-related value.SOLUTION: In a suspension control system 10, an actuator adjusts a suspension stroke of a control object wheel of a vehicle. An acquisition part 80 acquires a road surface displacement related value related to displacement in a vertical direction of a road surface at a prediction passage position of the control object wheel after a predetermined time from a current time, from a road surface data map in which the road surface displacement related value and a position are related with each other. A calculation part 86 calculates target control force on the basis of the acquired road surface displacement related value. A control part 88 controls the actuator, so that the control force generated by the actuator coincides with the target control force, when the control object wheel passes through the prediction passage position. When a winker of the vehicle starts an operation, the calculation part 86 calculates the target control force so that a change amount per unit time of the target control force is decreased compared with a case in which the winker is not operated.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a suspension control system. [Background technology]

[0002] Patent Document 1 discloses a vibration-damping control device for a vehicle. The vibration-damping control device acquires a road surface displacement-related value at a predicted passing position as preview information based on measurement data, and executes preview vibration-damping control that controls a control force generating device based on a final target control force including a first target control force calculated using the preview information. The measurement data includes data in which a road surface displacement-related value acquired when a measurement vehicle actually travels on a road surface is associated with position information indicating a position when the road surface displacement-related value was acquired. When the vibration-damping control device determines that there is a high probability that the road surface condition has changed since a past point in time, it sets the magnitude of the first target control force to a small value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-064361 Summary of the Invention [Problem to be solved by the invention]

[0004] A vehicle under preview vibration suppression control is more likely to travel in a place where there is no road surface displacement-related value in the map of measurement data when changing lanes or turning right or left at an intersection, compared to when traveling straight. In this case, at the boundary between the presence and absence of the road surface displacement-related value, the road surface displacement-related value changes from a certain value to zero. Therefore, even if there is no actual step on the road surface at this boundary, vibration may occur. In addition, control when crossing the boundary may cause lateral forces due to roll steer, camber, lateral displacement of the contact point, etc. to occur on the tire contact surface, which may cause lateral vibration or cause a difference from the driving trajectory intended by the driver. It is desirable to suppress the occurrence of such vibrations and lateral forces.

[0005] An object of the present invention is to provide a suspension control system that can suppress the occurrence of vibrations and lateral forces at the boundary between the presence and absence of a road surface displacement-related value. [Means for solving the problem]

[0006] In order to solve the above problem, a suspension control system according to an embodiment of the present invention includes an actuator that adjusts a suspension stroke of a controlled wheel of a vehicle, and a control device that controls the actuator. The control device includes an acquisition unit that acquires a road surface displacement-related value at a predicted passing position of the controlled wheel a predetermined time after a current time from a road surface data map in which a road surface displacement-related value related to a vertical displacement of a road surface is associated with a position, a calculation unit that calculates a target control force based on the acquired road surface displacement-related value, and a control unit that controls the actuator so that a control force generated by the actuator when the controlled wheel passes the predicted passing position coincides with the target control force. When a turn signal of the vehicle starts to operate, the calculation unit calculates the target control force so that a change amount per unit time of the target control force is smaller than when the turn signal is not operating. Effect of the Invention

[0007] According to the present invention, it is possible to provide a suspension control system that can suppress the occurrence of vibrations and lateral forces at the boundary between the presence and absence of a road surface displacement-related value. [Brief description of the drawings]

[0008] [Figure 1] FIG. 4 is a diagram showing an example of a map of road surface displacement-related values. [Diagram 2] 1 is a diagram illustrating a schematic configuration of a vehicle according to an embodiment. [Diagram 3] FIG. 3 is a diagram illustrating a schematic configuration of the suspension in FIG. 2. [Figure 4] 1 is a block diagram showing a configuration example of a suspension control system according to an embodiment; [Diagram 5]1 is a block diagram showing an example of a configuration of a map management device according to an embodiment; [Figure 6] 4 is a flowchart showing a suspension control process according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Before describing the embodiment in detail, the knowledge on which the embodiment is based will be described. As described above, compared to when traveling straight, when changing lanes or turning right or left at an intersection, the probability that the vehicle will travel through a location on the map where there is no road surface displacement-related value is higher.

[0010] FIG. 1 shows an example of a map of road surface displacement-related values. In this map, the magnitude of the road surface displacement-related value is represented by a shade of color. A uniform shade of color in an area 302 indicates that there is no map and the road surface displacement-related value is zero. This map is generated along each lane of a straight road. Areas 300a, 300b, and 300c correspond to different lanes. In areas 300a, 300b, and 300c, there is a map and the road surface displacement-related value is set at each position. Area 302 is an area other than areas 300a, 300b, and 300c. In area 302, there is no map and the road surface displacement-related value is uniformly zero regardless of the position. In this example, there is no map in area 302 between two adjacent lanes, that is, area 302 between area 300a and area 300b and area 302 between area 300a and area 300c, because no vehicle has driven there in the past to collect measurement data.

[0011] When a vehicle travelling along a route 304 in a lane with a large input changes lanes to the next lane, the vehicle moves from a location in area 300a where the road surface displacement-related value is large, across area 302 where the road surface displacement-related value is zero, to another lane corresponding to area 300b where the road surface displacement-related value is present. Therefore, when the vehicle crosses the border of the map, the road surface displacement-related value changes significantly even if there is no actual road surface input, causing large vibrations in the vehicle. Also, as described above, lateral forces are generated.

[0012] If vibrations or lateral forces occur at the boundary between the presence and absence of a map, the user of the vehicle may feel an uncomfortable ride due to the execution of preview control.

[0013] Therefore, in the embodiment, when the turn signal of the vehicle starts to operate, the amount of change in the target control force per unit time is reduced by lowering the gain of the preview control, etc. This makes it possible to suppress the generation of vibrations and lateral forces when the turn signal is operating, which is likely to cross the boundary, without affecting the control performance except when the turn signal is operating.

[0014] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the description, the same elements are denoted by the same reference numerals, and duplicated description will be omitted as appropriate.

[0015] 1. Suspension and road surface displacement related values 2 shows a schematic configuration of a vehicle 1 according to an embodiment. The vehicle 1 includes a left front wheel 2FL, a right front wheel 2FR, a left rear wheel 2RL, a right rear wheel 2RR, a suspension 3FL, a suspension 3FR, a suspension 3RL, a suspension 3RR, and a suspension control system 10. The left front wheel 2FL, the right front wheel 2FR, the left rear wheel 2RL, and the right rear wheel 2RR are provided with corresponding suspensions 3FL, 3FR, 3RL, and 3RR, respectively. Hereinafter, unless otherwise required, each wheel will be referred to as a wheel 2, and each suspension will be referred to as a suspension 3.

[0016] FIG. 3 shows a schematic configuration of the suspension 3 in FIG. 2. The suspension 3 is provided to connect between the unsprung structure 4 and the sprung structure 5 of the vehicle 1. The unsprung structure 4 includes the wheels 2. The suspension 3 includes a spring 3S, a damper 3D, and an actuator 3A. The damper 3D is also called a shock absorber. 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 actuator 3A controls the stroke of the suspension 3. The spring 3S has a spring constant K. The damper 3D has a damping coefficient C. The actuator 3A applies a vertical control force Fc between the unsprung structure 4 and the sprung structure 5, thereby adjusting the stroke of the suspension 3.

[0017] More specifically, the actuator 3A is, for example, an electric or hydraulic active actuator, and is an actuator constituting a so-called full active suspension. Alternatively, the actuator 3A may be, for example, an actuator that varies the damping force generated by the damper 3D, or an actuator of an active stabilizer device. Furthermore, the "actuator" of the present disclosure may be, for example, an actuator such as an electric motor that generates a vehicle longitudinal force in a vehicle equipped with a suspension configured to be able to convert the driving force and braking force acting on the wheels, which are the vehicle longitudinal forces, into a control force Fc by utilizing the suspension geometry. The electric motor may be, for example, an in-wheel motor (IWM) provided on the wheel, or may be an electric motor capable of driving the wheel via a vehicle drive shaft.

[0018] 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.

[0019] The wheel 2 moves on the road surface RS. Hereinafter, values ​​related to the road surface displacement Zr will be referred to as "road surface displacement-related values". Examples of the road surface displacement-related values ​​include the road surface displacement Zr, the road surface displacement velocity Zr' which is the time derivative value of 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', and the sprung acceleration Zs'', etc. The road surface displacement-related values ​​can also be said to be "vertical movement parameters" which are parameters related to the vertical movement of the wheel 2.

[0020] As an example, the case where the road surface displacement-related value is the unsprung displacement Zu will be described below. When generalizing, the "unsprung displacement" in the following description should be read as the "road surface displacement-related value".

[0021] Here, an example of the unsprung displacement calculation process will be described. First, the sprung acceleration Zs'' is detected by the sprung acceleration sensor 22 installed in the sprung structure 5. Next, the sprung displacement Zs is calculated by integrating the sprung acceleration Zs'' twice.

[0022] Next, a stroke ST, which is a relative displacement between the sprung structure 5 and the unsprung structure 4, is obtained. "Stroke ST" = "Sprung displacement Zs" - "Unsprung displacement Zu". For example, the stroke ST is detected by a stroke sensor installed in the suspension 3. As another example, the stroke ST may be estimated based on the sprung acceleration Zs'' by an observer configured based on a single wheel two-degree-of-freedom model.

[0023] Next, in order to suppress the influence of sensor drift and the like, a filtering process is performed on the time series data of the sprung displacement Zs. Similarly, a filtering process is performed on the time series data of the stroke ST. For example, the filter is a band-pass filter that passes signal components in a specific frequency band. The specific frequency band may be set so as to include the sprung resonance frequency of the vehicle 1. For example, the specific frequency band is 0.3 to 10 Hz.

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

[0025] Instead of performing filtering processing on the time series data of the sprung displacement Zs and the stroke ST, filtering processing may be performed on the time series data of the calculated unsprung displacement Zu.

[0026] As yet another example, the unsprung acceleration Zu'' may be detected by an unsprung acceleration sensor, and the unsprung displacement Zu may be calculated from the unsprung acceleration Zu''.

[0027] 2.Suspension control system 4 is a block diagram showing an example of the configuration of a suspension control system 10 according to an embodiment. The suspension control system 10 is mounted on a vehicle 1. The suspension control system 10 includes a vehicle state sensor 20, a blinker detection unit 30, a position sensor 40, a communication device 50, an actuator 3A, and an ECU 70. The ECU 70 is an electronic control unit.

[0028] The vehicle state sensor 20 detects the state of the vehicle 1 and supplies the detection result to the ECU 70. The vehicle state sensor 20 includes a vehicle 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 a stroke sensor 23 that detects the stroke ST. The vehicle state sensor 20 may include an unsprung acceleration sensor. The vehicle state sensor 20 may include a lateral acceleration sensor, a yaw rate sensor, a steering angle sensor, etc.

[0029] The blinker detection unit 30 detects the operation state of the blinker of the vehicle 1 and supplies the detection result to the ECU 70. The blinker detection unit 30 detects whether or not the blinker is operating. A known technique can be used to detect the operation state of the blinker. The blinker detection unit 30 may detect whether or not a blinker switch in the passenger compartment of the vehicle 1 has been operated.

[0030] The position sensor 40 detects the position and orientation of the vehicle 1, and supplies the detected position information to the ECU 70. For example, the position sensor 40 includes a Global Navigation Satellite System (GNSS) receiver.

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

[0032] The ECU 70 is a computer that controls the vehicle 1. The ECU 70 includes a processor 71 and a storage device 72. The processor 71 executes various processes. For example, the processor 71 includes a CPU (Central Processing Unit). The storage device 72 stores various information required for processing by the processor 71. Examples of the storage device 72 include a volatile memory, a non-volatile memory, a HDD (Hard Disk Drive), and an SSD (Solid State Drive).

[0033] The processor 71 has an acquisition unit 80, a prediction unit 82, a calculation unit 86, and a control unit 88. The processor 71 executes a suspension control program stored in the storage device 72 to realize the functions of the acquisition unit 80, the prediction unit 82, the calculation unit 86, and the control unit 88. The suspension control program may be recorded in a computer-readable recording medium. The ECU 70 corresponds to an example of a "control device" in the present disclosure.

[0034] The storage device 72 stores an unsprung displacement map 200. The unsprung displacement map 200 will be described in detail later.

[0035] The ECU 70 controls the actuator 3A to control the suspension 3. Specifically, the ECU 70 performs vibration suppression control to suppress vibration of the vehicle 1 by controlling the suspension 3. The ECU 70 controls the actuator 3A to generate a vertical control force Fc between the unsprung structure 4 and the sprung structure 5 as shown in FIG. 3. The vibration suppression control includes a "preview control" to be described later. The vibration suppression control will be described in detail later.

[0036] 3.Map management device 3-1. Configuration example 5 is a block diagram showing an example of a configuration of a map management device 100 according to an embodiment. The map management device 100 is a computer that manages various types of map information. The management of map information includes the generation, update, provision, and distribution of the map information. Typically, the map management device 100 is a management server on a cloud. The map management device 100 may be a distributed system in which multiple servers perform distributed processing.

[0037] The map management device 100 includes a communication device 110. The communication device 110 is connected to a communication network N1. For example, the communication device 110 communicates with a large number of vehicles 1 via the communication network N1.

[0038] The map management device 100 further includes a processor 120 and a storage device 130. The processor 120 executes various information processing. For example, the processor 120 includes a CPU. The storage device 130 stores various map information. The storage device 130 also stores various information required for processing by the processor 120. Examples of the storage device 130 include a volatile memory, a non-volatile memory, a HDD, and an SSD.

[0039] The map management program is a computer program for map management, and is executed by the processor 120. The map management program is stored in the storage device 130. Alternatively, the map management program may be recorded in a computer-readable recording medium. The functions of the map management device 100 are realized by the processor 120 executing the map management program.

[0040] The processor 120 communicates with the suspension control system 10 of the vehicle 1 via the communication device 110. The processor 120 collects various information from the suspension control system 10, and generates and updates map information based on the collected information. The processor 120 distributes the map information to the suspension control system 10. The processor 120 provides the map information in response to a request from the suspension control system 10.

[0041] 3-2.Unsprung displacement map One of the map information managed by the map management device 100 is an unsprung displacement map 200. The unsprung displacement map 200 is a map relating to unsprung displacement Zu, which is a road surface displacement-related value. The unsprung displacement map 200 is stored in the storage device 130. The unsprung displacement map 200 corresponds to an example of a "road surface data map in which a road surface displacement-related value related to the vertical displacement of the road surface is associated with a position" in the present disclosure.

[0042] The unsprung displacement map 200 represents the correspondence relationship between the position (X, Y) and the unsprung displacement Zu on the XY plane. In other words, the unsprung displacement map represents the unsprung displacement Zu as a function of the position (X, Y). 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 position is defined by the latitude and longitude.

[0043] The road area may be divided into a mesh shape on a horizontal plane. That is, the road area may be divided into a plurality of unit areas (hereinafter referred to as "road surface sections") on a horizontal plane. The road surface section 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 road surface section and the unsprung displacement Zu. The position of the road surface section may be defined by a representative position of the road surface section, for example, a central position, or may be defined by a latitude range and a longitude range of the road surface section. The unsprung displacement Zu of the road surface section is, for example, an average value of the unsprung displacement Zu acquired within the road surface section. The smaller the road surface section is, the higher the resolution of the unsprung displacement map 200 is.

[0044] 3-3. Map generation and update processing The processor 120 collects information from multiple vehicles 1 via the communication device 110. Then, the processor 120 generates and updates the unsprung displacement map 200 based on the information collected from the multiple vehicles 1.

[0045] The positions in the unsprung displacement map 200 are positions through which the wheels 2 have passed. The position of each wheel 2 is calculated based on position information detected by the position sensor 40. Specifically, the relative positional relationship between a reference point of the vehicle position on the vehicle 1 and each wheel 2 is known information. The position of each wheel 2 can be calculated based on the relative positional relationship and the vehicle position indicated by the position information.

[0046] The unsprung displacement Zu is calculated by the method described above. That is, the sprung displacement Zs and the stroke ST are obtained by using the vehicle state sensor 20 mounted on the vehicle 1. For convenience, the sprung displacement Zs and the stroke ST are called "sensor-based information." The unsprung displacement Zu is calculated based on this sensor-based information.

[0047] For example, while the vehicle 1 is traveling, the ECU 70 of the suspension control system 10 calculates the unsprung displacement Zu in real time based on the sensor-based information. The ECU 70 also associates the wheel position and the unsprung displacement Zu at the same timing. The ECU 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 device 100. The processor 120 of the map management device 100 generates and updates an unsprung displacement map based on the time series data of the wheel position and the time series data of the unsprung displacement Zu.

[0048] As another example, the ECU 70 of the suspension control system 10 associates the wheel positions with the sensor-based information at the same timing. Then, the ECU 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 device 100. The processor 120 of the map management device 100 calculates the unsprung displacement Zu based on the received sensor-based information. Furthermore, the processor 120 generates and updates an unsprung displacement map based on the time-series data of the wheel positions and the time-series data of the unsprung displacement Zu.

[0049] The processor 120 of the map management device 100 acquires map update information from the suspension control system 10 of the vehicle 1 via the communication device 110. The map update information includes time series data of the wheel positions, which are the positions of the vehicle 1. The map update information also includes time series data of sensor-based information 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 ECU 70 of the suspension control system 10.

[0050] The processor 120 of the map management device 100 generates and updates the unsprung displacement map 200 based on the map update information.

[0051] The suspension control system 10 of the vehicle 1 may hold a database of the unsprung displacement map 200 and generate and update its own unsprung displacement map 200. In other words, the map management device 100 may be included in the suspension control system 10.

[0052] 4. Preview control using unsprung displacement map The ECU 70 of the suspension control system 10 communicates with the map management device 100 via the communication device 50. The ECU 70 acquires an unsprung displacement map 200 of an area including the current position of the vehicle 1 from the map management device 100. The unsprung displacement map 200 is stored in the storage device 72. Then, the ECU 70 executes preview control, which is a type of vibration suppression control, based on the unsprung displacement map 200. The preview control is executed to reduce vibration of the sprung structure 5.

[0053] The acquisition unit 80, the prediction unit 82, the calculation unit 86, and the control unit 88 repeatedly execute the following process for each time step for each of the four control target wheels.

[0054] The acquisition unit 80 acquires the current position 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. The position of each wheel 2 can be calculated based on the relative positional relationship and the vehicle position indicated by the position information.

[0055] The acquisition unit 80 calculates a predicted passing position Pf of the wheel 2 after a preview time tp from the current time. The preview time tp is a predetermined time, and is set in advance to be, for example, a time required from when the acquisition unit 80 specifies the predicted passing position Pf until the actuator 3A of the suspension 3 outputs a control force Fc corresponding to the target control force Fc_t. 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 forward in the vehicle traveling direction from the current position by the preview distance Lp along the predicted moving path along which the wheel 2 is predicted to move. The predicted moving path can be specified, for example, based on the traveling direction of the vehicle 1 and the current position P0 of the wheel 2. The traveling direction can be specified, for example, by the following method. That is, the acquisition unit 80 maps the current position P0 of the previous time step and the current position P0 of the current time step to map information, and then specifies the direction from the current position of the previous time step toward the current position P0 of the current time step as the traveling direction. As a modified example, the acquisition unit 80 may calculate a 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.

[0056] The acquisition unit 80 reads out and acquires the unsprung displacement Zu at the calculated predicted passing position Pf from the unsprung displacement map 200.

[0057] When the blinker is not operating, the calculation unit 86 executes normal preview control. That is, when the blinker is not operating, the calculation unit 86 calculates a target control force Fc_t of the actuator 3A of the suspension 3 based on the unsprung displacement Zu at the predicted passing position Pf acquired by the acquisition unit 80. The target control force Fc_t is calculated, for example, as follows. This target control force Fc_t corresponds to a required value of the control force Fc required for the preview control.

[0058] The equation of motion for the sprung structure 5 in FIG. 3 is expressed by the following equation (1).

[0059] m·Zs''=C(Zu'-Zs')+K(Zu-Zs)-Fc ···(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. If the vibration of the sprung structure 5 is completely cancelled out by the control force Fc, then Zs''=0, Zs'=0, Zs=0, and the control force Fc is expressed by the following equation (2).

[0060] Fc = C Zu' + K Zu (2) The control force Fc that provides at least the vibration damping effect is expressed by the following formula (3).

[0061] Fc=α·C·Zu'+β·K·Zu ···(3) In formula (3), the control gain α is greater than 0 and less than or equal to 1, and the control gain β is also greater than 0 and less than or equal to 1. When the differential term in formula (3) is omitted, a control force Fc that provides at least a vibration damping effect is expressed by the following formula (4).

[0062] Fc = β K Zu (4) The calculation unit 86 calculates the target control force Fc_t according to the above formula (3) or formula (4). That is, the calculation unit 86 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). When the blinker is not operating, the calculation unit 86 sets the control gain α and the control gain β to predetermined reference values. The reference value of the control gain α and the reference value of the control gain β may be different or the same. The reference values ​​can be appropriately determined by experiments or simulations. When formula (4) is used, the control gain β only needs to be set to the reference value.

[0063] The control unit 88 transmits a control command including the target control force Fc_t to the actuator 3A so that the actuator 3A generates a control force Fc corresponding to the target control force Fc_t. The actuator 3A generates a control force Fc corresponding to the target control force Fc_t at a timing after the preview time tp from the current time, that is, at the timing when the wheel 2 passes the predicted passing position Pf. In other words, the control unit 88 controls the actuator 3A so that the control force Fc generated by the actuator 3A when the control target wheel passes the predicted passing position Pf coincides with the target control force Fc_t.

[0064] In this way, according to the preview control using the unsprung displacement map 200, when the blinker is not operating, it is possible to generate, at an appropriate timing, the control force Fc that suppresses the vibration of the sprung structure 5 caused by the unsprung displacement Zu of the predicted passing position Pf of the wheel 2. This makes it possible to effectively suppress the vibration of the sprung structure 5.

[0065] On the other hand, when the blinker starts to operate, there is a possibility that a lane change or a right or left turn at an intersection will occur, increasing the probability that the vehicle will travel in a location where there is no unsprung displacement Zu in the unsprung displacement map 200. Therefore, assuming that the above-described control based on the acquired unsprung displacement Zu is continued, there is a high concern that a lateral force that would not normally occur will be generated or that the control will increase vibrations beyond the original input, so a process for reducing vibrations is executed.

[0066] When the blinker starts to operate, the calculation unit 86 calculates the target control force Fc_t so that the amount of change in the target control force Fc_t per unit time is smaller than when the blinker is not operating. The amount of change in the target control force Fc_t per unit time is the difference between the target control force Fc_t calculated in the previous time step and the target control force Fc_t calculated in the current time step. The amount of change in the target control force Fc_t per unit time is expressed as an absolute value.

[0067] For example, when the blinker starts to operate, the calculation unit 86 gradually reduces each of the control gains α and β from the reference value to a predetermined reduction value, and when the blinker stops operating, the calculation unit 86 gradually increases each of the control gains α and β from the reduction value to the reference value. This process is called vibration reduction process. The reduction value of the control gains α and the reduction value of the control gains β may be different or the same. The reduction value can be appropriately determined by experiment or simulation so as to reduce vibration. The reduction value may be zero. In this case, the preview control is stopped while the control gains α and β are zero. When using the formula (4), it is only necessary to change the control gain β.

[0068] By such control, the amount of change per unit time of the target control force Fc_t is smaller than when the blinker is not in operation, even when the vehicle 1 passes the boundary between the presence and absence of the unsprung displacement Zu in the unsprung displacement map 200. Therefore, the generation of vibration and lateral force in the sprung structure 5 can be suppressed. For example, when the vehicle 1 travels along the route 304 in FIG. 1 and the blinker starts to operate while traveling in the area 300a, the generation of vibration and lateral force in the sprung structure 5 can be suppressed when crossing the area 302, compared to the comparative example in which the vibration reduction process is not executed. The control gain is reduced from the reference value only while the blinker is in operation and for a certain period of time thereafter, so there is no effect on the vibration suppression control other than this.

[0069] At this time, if the amount of change in the control gains α and β per unit time is too large, a sudden change in the control gains α and β may cause vibration or lateral force, so the control gains α and β are changed gradually to a degree that does not cause vibration or lateral force. This makes it possible to suppress sudden changes in the target control force Fc_t, thereby more effectively suppressing the occurrence of vibration and lateral force.

[0070] When the blinker starts to operate, the prediction unit 82 predicts whether the vehicle 1 will change lanes or turn right or left. For example, the prediction unit 82 may make a prediction based on guidance information of a car navigation system (not shown). The prediction unit 82 may also predict a lane change if the vicinity of the current position is not an intersection based on map information, and may predict a right or left turn if the vicinity of the current position is an intersection. The prediction unit 82 may make a prediction based on future route information if the vehicle 1 is in an automatic driving state. The prediction unit 82 may predict a lane change if the steering speed or steering amount is equal to or less than a predetermined threshold value, and may predict a right or left turn if the steering speed or steering amount is greater than the threshold value.

[0071] The calculation unit 86 may calculate the target control force Fc_t so that the reduction amount of the change amount per unit time of the target control force Fc_t is larger when the prediction unit 82 predicts that the vehicle 1 will change lanes than when the vehicle 1 is predicted to turn right or left. In other words, when turning right or left, the unsprung displacement Zu of the unsprung displacement map 200 is more likely to continue to exist than when changing lanes, so the reduction amount of the change amount per unit time of the target control force Fc_t may be smaller. In the case of turning right or left, if another vehicle or the vehicle 1, which is the vehicle itself, has traveled on a route on which the vehicle 1 will turn right or left in the past, the unsprung displacement Zu of the unsprung displacement map 200 exists. On the other hand, in the case of a lane change, the possibility of changing lanes at the same place is low, and the possibility of the unsprung displacement Zu of the unsprung displacement map 200 existing on the route to be traveled in the lane change this time is quite low.

[0072] For example, when the blinker starts to operate, if it is predicted that a lane change will occur, the calculation unit 86 may gradually decrease each of the control gains α and β from the reference value to a predetermined first reduction value, and when the blinker stops operating, the calculation unit 86 may gradually increase each of the control gains α and β from the first reduction value to the reference value. This processing may also be called strong vibration reduction processing. On the other hand, when the blinker starts to operate, if it is predicted that a right or left turn will occur, the calculation unit 86 may gradually decrease each of the control gains α and β from the reference value to a predetermined second reduction value, and when the blinker stops operating, the calculation unit 86 may gradually increase each of the control gains α and β from the second reduction value to the reference value. This processing may also be called weak vibration reduction processing.

[0073] The first reduction value of the control gain α is smaller than the second reduction value of the control gain α. The first reduction value of the control gain β is smaller than the second reduction value of the control gain β. The first reduction value may be zero. The first reduction value of the control gain α and the first reduction value of the control gain β may be different or the same. The second reduction value of the control gain α and the second reduction value of the control gain β may be different or the same. The first reduction value and the second reduction value can be appropriately determined by experiment or simulation so as to reduce vibration.

[0074] This makes it possible to more effectively suppress vibrations during lane changes, in which there is a higher probability of passing the boundary between the presence and absence of unsprung displacement Zu in the unsprung displacement map 200, compared to right and left turns.

[0075] Alternatively, the control gains α and β may be fixed. In this case, when the blinker starts to operate, the calculation unit 86 may calculate the target control force Fc_t so that the amount of change per unit time of the target control force Fc_t is small by applying a rate limiter to the time series data of the unsprung displacement Zu acquired in the current time step and the past time steps. The rate limiter limits the amount of change per unit time of the unsprung displacement Zu to a predetermined limit value or less. It can also be said that the rate limiter suppresses the amount of change that can be made in the unsprung displacement Zu from the previous time step to the current time step.

[0076] That is, the calculation unit 86 corrects the value of the unsprung displacement Zu acquired at the current time step using a rate limiter, thereby making the amount of change in the unsprung displacement Zu per unit time smaller than before the correction. Then, the calculation unit 86 substitutes the corrected unsprung displacement Zu into equation (3) or equation (4) to calculate the target control force Fc_t.

[0077] The calculation unit 86 calculates the target control force Fc_t so as to limit the amount of change in the target control force Fc_t per unit time by applying a rate limiter while the turn signal is in operation, or while the turn signal is in operation and for a predetermined control time after the turn signal has ended. In other words, when the turn signal has ended operation, or when the control time has elapsed since the turn signal has ended operation, the limit value and the control time can be appropriately determined by experiment or simulation so as to reduce vibration of the sprung structure 5. This process can also provide the same effect as when the control gain is changed.

[0078] In addition, when the blinker starts to operate, the calculation unit 86 may apply a low-pass filter instead of a rate limiter to the time series data of the unsprung displacement Zu acquired at the current time step and the past time steps while the blinker is operating, or while the blinker is operating and during the control time after the blinker has stopped operating. The calculation unit 86 can also limit the amount of change per unit time of the target control force Fc_t by this process. That is, the calculation unit 86 corrects the value of the unsprung displacement Zu acquired at the current time step using a low-pass filter, thereby making the amount of change per unit time of the unsprung displacement Zu smaller than before the correction, thereby suppressing a steep change in the unsprung displacement Zu. The cutoff frequency of the low-pass filter can be appropriately determined by experiment or simulation so that the vibration of the sprung structure 5 is reduced.

[0079] Alternatively, when the blinker starts to operate, the calculation unit 86 may apply a rate limiter or a low-pass filter to the time series data of the target control force Fc_t calculated at the current time step and the past time step, instead of the unsprung displacement Zu. In this case, the calculation unit 86 may also apply the rate limiter or the low-pass filter while the blinker is operating, or while the blinker is operating and for the control time after the blinker has stopped operating. Through this process, the calculation unit 86 can calculate the target control force Fc_t so that the amount of change in the target control force Fc_t per unit time is small.

[0080] That is, the calculation unit 86 substitutes the unsprung displacement Zu acquired by the acquisition unit 80 into equation (3) or equation (4) without correction to calculate the target control force Fc_t. The calculation unit 86 applies a rate limiter or a low-pass filter to correct the value of the target control force Fc_t calculated at the current time step, thereby making the amount of change in the target control force Fc_t per unit time smaller than before correction. Then, the calculation unit 86 supplies the corrected target control force Fc_t to the control unit 88.

[0081] Furthermore, when the prediction unit 82 predicts that the vehicle 1 will change lanes, the calculation unit 86 may increase the strength of the rate limiter by decreasing the limiting value of the rate limiter compared to when the vehicle 1 is predicted to turn right or left. Also, when the prediction unit 82 predicts that the vehicle 1 will change lanes, the calculation unit 86 may increase the strength of the low-pass filter by decreasing the cutoff frequency of the low-pass filter or increasing the order or number of stages of the low-pass filter compared to when the vehicle 1 is predicted to turn right or left. In other words, even when the rate limiter or the low-pass filter is used, the calculation unit 86 may increase the reduction amount of the change amount per unit time of the target control force Fc_t when the prediction unit 82 predicts that the vehicle 1 will change lanes compared to when the vehicle 1 is predicted to turn right or left.

[0082] 6 is a flowchart showing the suspension control process according to the embodiment. The process of this flowchart is repeatedly executed for each of the control target wheels at predetermined time steps while the vehicle 1 is traveling.

[0083] The acquisition unit 80 acquires the current position of the wheel 2 (S10), acquires the predicted passing position Pf of the wheel 2 (S12), and acquires the unsprung displacement Zu of the predicted passing position Pf of the wheel 2 from the unsprung displacement map 200 (S14).

[0084] The ECU 70 acquires the operation state of the blinker from the blinker detection unit 30 (S16). If the blinker is in operation (Y in S18), and if a lane change is predicted (Y in S20), the calculation unit 86 executes strong vibration reduction processing to calculate the target control force Fc_t (S22), and the control unit 88 controls the actuator 3A (S24), and the processing ends.

[0085] If a lane change is not predicted in S20 (N in S20), the calculation unit 86 executes weak vibration reduction processing to calculate the target control force Fc_t (S26), and the processing proceeds to S24.

[0086] If the blinker is not in operation in S18 (N in S18), the calculation unit 86 calculates the target control force Fc_t without executing the vibration reduction process (S28), and the process proceeds to S24.

[0087] According to the embodiment, when the turn signal starts to operate, the target control force Fc_t is calculated so that the amount of change per unit time of the target control force Fc_t is small, so that the occurrence of vibrations and lateral forces at the boundary can be suppressed during turn signal operation, which is likely to cross the boundary between the presence and absence of a road surface displacement-related value. There is no effect on control other than the boundary between the presence and absence of a road surface displacement-related value. This makes it possible to suppress the discomfort of the ride caused by the execution of the preview control.

[0088] The present invention has been described above based on the embodiments. The embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component and each processing step, and that such modifications are also within the scope of the present invention.

[0089] (First Modification) The control unit 88 may execute the following feedback control as vibration damping control in addition to the above-mentioned preview control by controlling the actuator 3A. That is, the feedback control is executed to reduce vibration of the sprung structure 5. The control force Fc in the example in which the preview control is performed together with the feedback control is expressed by, for example, the following equation (5). In this example, the calculation unit 86 calculates the target control force Fc_t according to equation (5).

[0090] Fc = β K Zu + γ Zs (5) The first term on the right side of equation (5) is the same as equation (4) above, and is a feedforward term related to preview control. The second term on the right side is a feedback term related to feedback control. This feedback term is the product of the feedback gain γ and the sprung displacement Zs at the time of calculating the target control force Fc_t. Note that instead of the sprung displacement Zs in the feedback term, any one of the sprung velocity Zs', sprung acceleration Zs'', unsprung displacement Zu, unsprung velocity Zu', and unsprung acceleration Zu'' at the time of calculating the target control force Fc_t may be used.

[0091] When the blinker is not operating, the calculation unit 86 sets the feedback gain γ of the feedback control to the basic gain γ0.

[0092] When the blinkers start to operate, the calculation unit 86 increases the feedback gain γ during execution of the vibration reduction process, compared to when the blinkers are not operating. That is, in this case, the calculation unit 86 sets the feedback gain γ to a gain γ1 that is greater than the basic gain γ0. In this case, the target control force Fc_t calculated according to the above formula (5) is greater than when the feedback gain γ is the basic gain γ0. That is, when the blinkers start to operate, feedback control is more actively utilized than when the blinkers are not operating.

[0093] As a result, during execution of the vibration reduction process in which the vibration damping effect of the preview control is temporarily weakened, vibration deterioration of the sprung structure 5 can be suppressed by more actively performing vibration damping using feedback control.

[0094] Furthermore, when using the prediction result by the prediction unit 82, the calculation unit 86 may increase the feedback gain γ when it is predicted that the vehicle 1 will change lanes compared to when it is predicted that the vehicle 1 will turn right or left. That is, the calculation unit 86 may set the gain γ1 as the feedback gain γ when it is predicted that the vehicle 1 will change lanes, and may set the gain γ2 as the feedback gain γ when it is predicted that the vehicle 1 will change lanes. The gain γ2 is larger than the basic gain γ0 and smaller than the gain γ1.

[0095] The basic gain γ0, the gain γ1, and the gain γ2 can be appropriately determined by experiments or simulations. The basic gain γ0, the gain γ1, and the gain γ2 are, for example, fixed values.

[0096] As a result, when changing lanes, where the vibration damping effect of the preview control is weakened to a greater extent than when turning right or left, vibration deterioration of the sprung structure 5 can be more effectively suppressed by more actively performing vibration damping using feedback control.

[0097] (Second Modification) When the blinker starts to operate, the control unit 88 may execute preview control for the rear wheels using the unsprung displacement Zu1 calculated for the passing position of the front wheels, in addition to the preview control using the unsprung displacement map 200 described above, during the execution of the vibration reduction process. Since the rear wheels are considered to follow the path of the front wheels, such control may be executed. In this case, the control force Fc is expressed by, for example, the following equation (6). In this example, the calculation unit 86 calculates the target control force Fc_t according to equation (6) during the execution of the vibration reduction process.

[0098] Fc=β·K·Zu+γa·Zu1 ···(6) The first term on the right side of equation (6) is the same as equation (4) above, and is a feedforward term related to preview control using the unsprung displacement map 200. The second term on the right side is a feedforward term related to preview control using the unsprung displacement Zu1 calculated for the passing position of the front wheels. The second term on the right side is the product of the gain γa and the unsprung displacement Zu1 of the passing position of the front wheels when the target control force Fc_t is calculated. As described above, the unsprung displacement Zu1 can be calculated using the detection value of the sprung acceleration sensor 22. The gain γa can be appropriately determined by experiment or simulation.

[0099] As a result, during execution of the vibration reduction process in which the vibration damping effect of the preview control using the unsprung displacement map 200 is temporarily weakened, the rear wheels are damped by preview control using the unsprung displacement Zu1 calculated for the passing position of the front wheels, thereby suppressing the deterioration of vibration of the sprung structure 5.

[0100] Furthermore, when using the prediction result by the prediction unit 82, the calculation unit 86 may increase the gain γa when it is predicted that the vehicle 1 will change lanes compared to when it is predicted that the vehicle 1 will turn right or left. That is, the calculation unit 86 may set the gain γa to a gain γa1 when it is predicted that the vehicle 1 will change lanes, and may set the gain γa to a gain γa2 smaller than the gain γa1 when it is predicted that the vehicle 1 will turn right or left. The gains γa1 and γa2 can be appropriately determined by experiments or simulations.

[0101] As a result, when changing lanes, where the vibration damping effect of the preview control using the unsprung displacement map 200 is weakened to a greater extent than when turning right or left, the deterioration of vibration in the sprung structure 5 can be more effectively suppressed by more actively performing vibration damping using the preview control using the unsprung displacement Zu1 calculated for the passing position of the front wheels.

[0102] (Third Modification) When the blinker starts to operate, the control unit 88 may execute preview control using a known preview sensor in addition to the preview control using the unsprung displacement map 200 described above during the execution of the vibration reduction process. The preview sensor (not shown) includes, for example, at least one of a camera sensor, a LiDAR, and a radar sensor. The preview sensor acquires the road surface displacement of the road surface ahead of the vehicle 1. In this case, the control force Fc is expressed, for example, by the following formula (7). In this example, the calculation unit 86 calculates the target control force Fc_t according to formula (7) during the execution of the vibration reduction process.

[0103] Fc=β·K·Zu+γb·Z0 ···(7) The first term on the right side of equation (7) is the same as equation (4) above, and is a feedforward term related to preview control using the unsprung displacement map 200. The second term on the right side is a feedforward term related to preview control using a preview sensor. The second term on the right side is the product of gain γb and the road surface displacement Z0 ahead of the vehicle 1 acquired by the preview sensor when calculating the target control force Fc_t. Gain γb can be appropriately determined by experiment or simulation. Preview control using a preview sensor is well known, so further detailed explanation will be omitted.

[0104] As a result, during execution of the vibration reduction process in which the vibration damping effect by the preview control using the unsprung displacement map 200 is temporarily weakened, the vibration deterioration of the sprung structure 5 can be suppressed by damping through preview control using the preview sensor.

[0105] Furthermore, when using the prediction result by the prediction unit 82, the calculation unit 86 may increase the gain γb when it is predicted that the vehicle 1 will change lanes compared to when it is predicted that the vehicle 1 will turn right or left. That is, the calculation unit 86 may set the gain γb to a gain γb1 when it is predicted that the vehicle 1 will change lanes, and may set the gain γb to a gain γb2 smaller than the gain γb1 when it is predicted that the vehicle 1 will turn right or left. The gains γb1 and γb2 can be appropriately determined by experiments or simulations.

[0106] As a result, when changing lanes, where the vibration damping effect of the preview control using the unsprung displacement map 200 is weakened to a greater extent than when turning right or left, vibration deterioration of the sprung structure 5 can be effectively suppressed by more actively performing vibration damping using preview control using a preview sensor.

[0107] At least two of the first, second and third modified examples may be combined.

[0108] In the embodiment, the preview control is performed on all four wheels 2 of the vehicle 1. However, the wheels that are the subject of the preview control are not limited to all wheels, and may be, for example, only the left and right front wheels or only the left and right rear wheels. [Explanation of symbols]

[0109] 1...vehicle, 2...wheel, 3...suspension, 3A...actuator, 5...sprung structure, 10...suspension control system, 30...blinker detection unit, 70...ECU (control unit), 80...acquisition unit, 82...prediction unit, 86...calculation unit, 88...control unit, 200...unsprung displacement map (road surface data map).

Claims

1. An actuator for adjusting a suspension stroke of a controlled wheel of the vehicle; A control device for controlling the actuator; Equipped with The control device includes: an acquisition unit that acquires a road surface displacement-related value at a predicted passing position of the control target wheel a predetermined time after a current time from a road surface data map in which a road surface displacement-related value related to a vertical displacement of the road surface is associated with a position; A calculation unit that calculates a target control force based on the acquired road surface displacement related value; a control unit that controls the actuator so that a control force generated by the actuator when the control target wheel passes through the predicted passing position coincides with the target control force; having The calculation unit calculates the target control force so that, when a turn signal of the vehicle starts to operate, a change amount of the target control force per unit time becomes smaller compared to a case where the turn signal is not operated. A suspension control system comprising:

2. The calculation unit is Calculating the target control force based on the acquired road surface displacement related value and gain; If the turn signal is not activated, the gain is set to a reference value; When the blinker starts to operate, the gain is gradually decreased from the reference value, When the blinker operation is completed, the gain is gradually increased to the reference value.

2. The suspension control system of claim 1.

3. The calculation unit calculates the target control force so as to limit a change amount of the target control force per unit time during operation of the blinker, or during operation of the blinker and for a predetermined control time after the blinker has finished operating.

2. The suspension control system of claim 1.

4. The control device further includes a prediction unit that predicts whether the vehicle will change lanes or turn right or left when the blinker starts to operate, The calculation unit calculates the target control force such that a reduction in a change amount of the target control force per unit time is greater when it is predicted that the vehicle will change lanes than when it is predicted that the vehicle will turn right or left.

4. A suspension control system according to claim 1.

5. The control unit further performs feedback control to reduce vibration of the sprung structure by controlling the actuator, The calculation unit is When the blinker starts to operate, a feedback gain of the feedback control is increased compared to when the blinker is not operating; When it is predicted that the vehicle will change lanes, the feedback gain is increased compared to when it is predicted that the vehicle will turn right or left.

5. The suspension control system of claim 4.

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