Vehicle suspension control device and vehicle suspension control method

Abstract

To achieve both ride comfort control and attitude control while considering a road surface state or while considering at least one of a vehicle operation state and a vehicle motion state.SOLUTION: A vehicular suspension control device includes an actuator, and an electronic control unit. The actuator controls a suspension stroke of a control object wheel. The electronic control unit executes first calculation processing for calculating a first demand control amount for ride comfort control to a road surface input, and second calculation processing for calculating a second demand control amount for attitude control to a vehicle operation input. Also, the electronic control unit executes arbitration processing for limiting the second demand control amount to be small on the basis of road surface input information in the case that the sum of the first demand control amount and the second demand control amount exceeds a control amount range outputtable by the actuator.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a vehicle suspension control device including an actuator for controlling a suspension stroke, and a vehicle suspension control method. [Background technology]

[0002] Patent Document 1 discloses an active suspension for a vehicle. This active suspension includes a hydraulic actuator that controls the suspension stroke, and a controller. An actuator is provided for each wheel. The controller controls the supply and discharge of fluid pressure to each actuator by independently operating a control valve in response to a drive control output obtained by adding a roll control output and a ride comfort control output for each wheel. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 02-151515 Summary of the Invention [Problem to be solved by the invention]

[0004] According to the technology described in Patent Document 1, in order to achieve both ride comfort control and roll control (posture control), the control valves of the actuators are independently controlled according to the drive control output obtained by adding the roll control output and the ride comfort control output for each wheel as described above. However, the output of the actuator that controls the suspension stroke is limited. For this reason, the actuator cannot always generate an output that satisfies both the roll control output and the ride comfort control output. Furthermore, even if the roll control output and the ride comfort control output are simply added as described in Patent Document 1, there is a possibility that appropriate suspension control will not be achieved depending on at least one of the road surface condition or the vehicle operation condition and the vehicle motion condition.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a vehicle suspension control device and a vehicle suspension control method that are capable of achieving both ride comfort control and posture control while taking into account road surface conditions or at least one of vehicle operation conditions and vehicle motion conditions. [Means for solving the problem]

[0006] A vehicle suspension control device according to an embodiment of the present disclosure includes an actuator and an electronic control unit. The actuator controls a suspension stroke of a controlled wheel. The electronic control unit executes a first calculation process to calculate a first required control amount for ride comfort control in response to a road surface input, and a second calculation process to calculate a second required control amount for attitude control in response to a vehicle operation input. In addition, when the sum of the first required control amount and the second required control amount exceeds a control amount range that can be output by the actuator, the electronic control unit executes an arbitration process to limit the second required control amount to a small amount based on road surface input information.

[0007] In the arbitration process, the electronic control unit may reduce the control gain included in the second required control amount as the road surface input included in the road surface input information increases.

[0008] In the arbitration process, the electronic control unit may reduce the control gain included in the second required control amount as the road surface input speed included in the road surface input information increases.

[0009] In the arbitration process, the electronic control unit may reduce the control gain included in the second required control amount as the high frequency component of the road surface input included in the road surface input information becomes larger.

[0010] In the arbitration process, when the road surface input included in the road surface input information is equal to or greater than a threshold value, the electronic control unit may limit the second required control amount to a small value based on the suspension spring characteristics.

[0011] The attitude control may include at least one of roll control and pitch control. Furthermore, limiting the second required control amount based on the suspension spring characteristic may include changing a control gain included in the second required control amount so that at least one of the roll angle and the pitch angle becomes zero.

[0012] A vehicle suspension control device according to another aspect of the present disclosure includes an actuator and an electronic control unit. The actuator controls a suspension stroke of a controlled wheel. The electronic control unit executes a first calculation process to calculate a first required control amount for ride comfort control in response to a road surface input, and a second calculation process to calculate a second required control amount for attitude control in response to a vehicle operation input. In addition, when the sum of the first required control amount and the second required control amount exceeds a control amount range that can be output by the actuator, the electronic control unit executes an arbitration process to limit the first required control amount to a small amount based on at least one of vehicle operation information and vehicle motion information.

[0013] In the arbitration process, the electronic control unit may reduce a control gain included in the first required control amount as the priority of posture control over ride comfort control, which is an index based on at least one of vehicle operation information and vehicle motion information, increases.

[0014] A vehicle suspension control method according to one aspect of the present disclosure controls a vehicle suspension having an actuator that controls a suspension stroke of a control target wheel. The control method includes a first calculation process that calculates a first required control amount for ride comfort control in response to a road surface input, a second calculation process that calculates a second required control amount for attitude control in response to a vehicle operation input, and an arbitration process that limits the second required control amount to a small amount based on road surface input information when the sum of the first required control amount and the second required control amount exceeds a control amount range that can be output by the actuator.

[0015] A vehicle suspension control method according to another aspect of the present disclosure controls a vehicle suspension having an actuator that controls a suspension stroke of a control target wheel. The control method includes a first calculation process that calculates a first required control amount for ride comfort control in response to a road surface input, a second calculation process that calculates a second required control amount for attitude control in response to a vehicle operation input, and an arbitration process that limits the first required control amount to a small amount based on at least one of vehicle operation information and vehicle motion information when the sum of the first required control amount and the second required control amount exceeds a control amount range that can be output by the actuator. Effect of the Invention

[0016] According to the vehicle suspension control device and vehicle suspension control method according to an embodiment of the present disclosure, when the sum of the first required control amount and the second required control amount exceeds the range of control amounts that can be output by the actuator, the second required control amount is limited to a small value based on the road surface input information. That is, in such a case, the ride comfort control is prioritized over the attitude control, taking into account the road surface input information. This makes it possible to achieve both the ride comfort control and the attitude control while taking into account the road surface condition.

[0017] According to a vehicle suspension control device and a vehicle suspension control method according to other aspects of the present disclosure, when the sum of the first required control amount and the second required control amount exceeds the range of control amounts that can be output by the actuator, the first required control amount is limited to a small value based on at least one of the vehicle operation information and the vehicle motion information. That is, in such a case, the attitude control is prioritized over the ride comfort control, taking into account at least one of the vehicle operation information and the vehicle motion information. This makes it possible to achieve both the ride comfort control and the attitude control while taking into account at least one of the vehicle operation state and the vehicle motion state. [Brief description of the drawings]

[0018] [Figure 1] 1 is a diagram illustrating an example of a configuration of a vehicle according to a first embodiment. [Diagram 2]1 is a conceptual diagram showing a configuration example of a suspension according to a first embodiment. [Diagram 3] FIG. 2 is a conceptual diagram for explaining preview control. [Figure 4] 4 is a flowchart showing a process related to suspension control according to the first embodiment. [Diagram 5] 11 is a diagram illustrating an example of a method for calculating a limit value X2lmt based on each of index values ​​Im, Iv, and If. FIG. [Figure 6] 13 is a diagram for explaining a specific example 2 of a method for calculating a limit value G2lmt using a combination of a plurality of road surface input index values ​​I. FIG. [Figure 7] FIG. 3 is a diagram showing spring characteristics of the suspension shown in FIG. 2. [Figure 8] 5 is a flowchart showing a process related to suspension control according to a first example regarding a restriction based on a suspension spring characteristic. [Figure 9] 10 is a flowchart showing a process related to suspension control according to the second embodiment. [Figure 10] 13 is a diagram for explaining an example of a method for calculating a limiting value X1lmt based on a priority P. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] In the embodiments described below, when reference is made to the number, quantity, amount, range, etc. of each element, the technical idea of ​​this disclosure is not limited to the mentioned numbers, unless otherwise specified or clearly specified in principle to that number.

[0020] 1. First embodiment 1-1.Vehicle configuration examples FIG. 1 is a diagram showing a schematic example of a configuration of a vehicle 1 according to a first embodiment. The vehicle 1 includes wheels 2 and a suspension 3. The wheels 2 include a left front wheel 2FL, a right front wheel 2FR, a left rear wheel 2RL, and a right rear wheel 2RR. Suspensions 3FL, 3FR, 3RL, and 3RR are provided for the left front wheel 2FL, the right front wheel 2FR, the left rear wheel 2RL, and the right rear wheel 2RR, respectively. In the following description, unless there is a particular need to distinguish between them, each wheel will be referred to as a wheel 2, and each suspension will be referred to as a suspension 3.

[0021] FIG. 2 is a conceptual diagram showing a configuration example of the suspension 3 according to the first embodiment. The suspension 3 is provided so as to connect between the unsprung structure 4 and the sprung structure 5 of the vehicle 1. The unsprung structure 4 includes a wheel 2. The sprung structure 5 includes a vehicle body 6. The suspension 3 includes a spring 3S, a damper (shock absorber) 3D, and an actuator 3A. The spring 3S, the damper 3D, and the actuator 3A are provided in parallel between the unsprung structure 4 and the sprung structure 5. The spring 3S has a spring constant K. The damper 3D has a damping coefficient C. The suspension 3 also includes a bump rubber (bump stopper) 3B. The bump rubber 3B is provided concentrically with the damper 3D.

[0022] The actuator 3A controls the stroke ST of the suspension 3 by applying a vertical control force Fc between the unsprung structure 4 and the sprung structure 5. The actuator 3A is, for example, an electric or hydraulic active actuator (an actuator constituting a so-called fully 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.

[0023] Furthermore, the vehicle 1 is equipped with an electronic control unit (ECU) 10. The ECU 10 is equipped with a processor, a storage device, and an input / output interface. The input / output interface takes in sensor signals from sensors 12 attached to the vehicle 1 and outputs operation signals to the actuator 3A. The storage device stores various control programs for controlling the actuator 3A. The processor reads out and executes the control programs from the storage device, thereby realizing suspension control (including ride comfort control and attitude control, which will be described later) using the actuator 3A.

[0024] The sensors 12 include, for example, an acceleration sensor that detects the lateral acceleration LA and longitudinal acceleration FA acting on the vehicle 1, a sprung acceleration sensor that detects the vertical acceleration of the sprung structure 5, a suspension stroke sensor, and a wheel speed sensor provided on each wheel 2. The wheel speed sensor can detect the vehicle speed V. The sensors 12 also include, for example, an accelerator position sensor and a brake position sensor that detect the depression amounts of an accelerator pedal and a brake pedal, respectively, and a steering angle sensor for the wheels 2. The sensors 12 further include a position sensor that detects the position and orientation of the vehicle 1. The position sensor includes, for example, a GNSS (Global Navigation Satellite System) receiver.

[0025] The vehicle 1 also includes a communication device 14. The ECU 10 communicates with the outside of the vehicle 1 via the communication device 14.

[0026] 1-2.Suspension control The suspension control of the vehicle 1 includes "ride comfort control in response to road surface input" and "posture control in response to vehicle operation input."

[0027] 1-2-1.Ride comfort control The ride comfort control for the road surface input is executed to reduce vibration (more specifically, vertical vibration) of the sprung structure 5 in response to the road surface input. The ride comfort control can also be said to be control that suppresses changes in the behavior of the sprung structure 5 associated with the road surface input in order to improve the ride comfort of the vehicle 1.

[0028] The ride comfort control is, for example, a preview control based on road surface information ahead of the vehicle. FIG. 3 is a conceptual diagram for explaining the preview control. The road surface information ahead of the vehicle can be acquired, for example, by the vehicle 1 from a management server on the cloud via the communication device 14 as a road surface data map. This road surface data map is a map in which road surface displacement-related values ​​related to the vertical displacement Zr (see FIG. 2) of the road surface are associated with data storage positions (positions on a map). Examples of the road surface displacement-related values ​​include the above-mentioned road surface displacement Zr, road surface displacement velocity Zr' which is a time differential value of the road surface displacement Zr, unsprung displacement Zu, unsprung velocity Zu', unsprung acceleration Zu'', sprung displacement Zs, sprung velocity Zs', sprung acceleration Zs'', and the like. A specific example of the road surface data map is an unsprung displacement map that uses the unsprung displacement Zu (see FIG. 2) as an example of the road surface displacement-related value. The road surface data map is generated and updated in advance based on information collected from a large number of vehicles including the vehicle 1. The road surface information ahead of the vehicle may be obtained, for example, from an image captured by a camera mounted in front of the vehicle, instead of from a road surface data map.

[0029] In the preview control, the ECU 10 acquires a current position P0 of each wheel 2. The relative positional relationship between a reference point of the vehicle position in 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. The position information here is acquired, for example, by using a position sensor included in the sensors 12. The position information may also be acquired by dead reckoning.

[0030] The ECU 10 calculates a predicted passing position Pf of the wheel 2 after the preview time tp. The preview time tp is set to, for example, a time equal to or longer than the time required for calculation processing and communication processing required to operate the actuator 3A of the suspension 3. The preview time tp may be fixed or may be variable depending on the situation. The preview distance Lp is given by the product of the preview time tp and the vehicle speed V. The predicted passing position Pf is a position that is the preview distance Lp ahead of the current position P0. As a modified example, the ECU 10 may calculate a predicted traveling route based on the vehicle speed V and the steering angle of the wheel 2, and calculate the predicted passing position Pf based on the predicted traveling route.

[0031] The ECU 10 reads out the unsprung displacement Zu at the predicted passing position Pf from the unsprung displacement map. Then, the ECU 10 calculates a target control force Fc_t of the actuator 3A of the suspension 3 based on the unsprung displacement Zu at the predicted passing position Pf. The target control force Fc_t is calculated, for example, as follows. This target control force Fc_t corresponds to a required value of the control force Fc required for the preview control (i.e., a required control amount Xpv described later).

[0032] The equation of motion for the sprung structure 5 (see FIG. 2) is expressed by the following equation (1). m·Zs''=C(Zu'-Zs')+K(Zu-Zs)-Fc ···(1)

[0033] In equation (1), m is the mass of the sprung structure 5, Zs is the sprung displacement, 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 (Zs''=0, Zs'=0, Zs=0), the control force Fc is expressed by the following equation (2). Fc = C Zu' + K Zu (2)

[0034] The control force Fc that provides at least the vibration damping effect is expressed by the following formula (3). Fc=α·C·Zu'+β·K·Zu ···(3)

[0035] 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). Fc = β K Zu (4)

[0036] The ECU 10 calculates the target control force Fc_t (i.e., the required control amount Xpv) according to the above formula (3) or formula (4). That is, the ECU 10 calculates the target control force Fc_t (required control amount Xpv) by substituting the unsprung displacement Zu at the predicted passing position Pf into formula (3) or formula (4).

[0037] The ECU 10 controls the actuator 3A so as to generate a target control force Fc_t (required control amount Xpv) at the timing when the wheel 2 passes through the predicted passing position Pf. The timing when the wheel 2 passes through the predicted passing position Pf can be known from the preview time tp.

[0038] According to the preview control described above, it is possible to effectively suppress vibration of the vehicle 1 (sprung structure 5).

[0039] The ride comfort control may be, instead of or in addition to the preview control, feedback control based on the skyhook control law for reducing vibration of the sprung structure 5 using at least one of the sprung displacement Zs, the sprung velocity Zs', and the sprung acceleration Zs'' (see, for example, JP 2019-135120 A). In addition, the feedback control based on the skyhook control law for reducing vibration of the sprung structure 5 may generate an output (control force Fc) proportional to the state quantity of the unsprung structure 4 (at least one of the unsprung displacement Zu, the unsprung velocity Zu', and the unsprung acceleration Zu'').

[0040] 1-2-2. Posture control The attitude control in response to a vehicle operation input includes at least one of roll control during turning accompanying steering of the vehicle 1 and pitch control accompanying acceleration / deceleration of the vehicle 1. In this embodiment, the roll control and pitch control are executed in combination as the attitude control. Alternatively, only one of the roll control and the pitch control may be executed as the attitude control.

[0041] The roll control here refers to control for generating a reverse roll moment by controlling the control force Fc of the actuator 3A so as to cancel out the roll that occurs when the vehicle 1 turns due to steering. More specifically, "canceling the roll" refers to suppressing the roll that occurs compared to the case without roll control, or generating a roll in the opposite direction to the roll that occurs. Similarly, the pitch control here refers to control for generating a reverse pitch moment by controlling the control force Fc of the actuator 3A so as to cancel out the pitch that occurs when the vehicle 1 accelerates or decelerates. More specifically, "canceling the pitch" refers to suppressing the pitch that occurs compared to the case without pitch control, or generating a pitch in the opposite direction to the pitch that occurs.

[0042] In addition, for each wheel 2, the control force Fc, which is the suspension generated force, is positive when it acts to lift the sprung structure 5 upward. Accordingly, each required control amount of the suspension control (e.g., Xr, Xp, and Xpv) is also positive when it acts to lift the sprung structure 5 upward. Therefore, the roll required control amount Xr is positive for the wheel 2 on the outside of the turn and negative for the wheel 2 on the inside of the turn. Similarly, the pitch required control amount Xp is negative for the front wheels 2FL and 2FR and positive for the rear wheels 2RL and 2RR during acceleration, and conversely, is positive for the front wheels 2FL and 2FR and negative for the rear wheels 2RL and 2RR during deceleration.

[0043] 1-2-3. Processing by ECU In the first embodiment, in order to achieve both ride comfort control and attitude control while taking into account the road surface condition, the processing by the ECU 10 includes the following "calculation processing" and "arbitration processing." That is, the ECU 10 executes a first calculation processing to calculate a first required control amount X1 for ride comfort control in response to a road surface input, and a second calculation processing to calculate a second required control amount X2 for attitude control in response to a vehicle operation input. Then, when the sum of the calculated first required control amount X1 and second required control amount X2 (i.e., the total required control amount Xt (=X1+X2)) exceeds the control amount range Rx that can be output by the actuator 3A, the ECU 10 executes an arbitration processing to limit the second required control amount X2 to a small value based on the road surface input information.

[0044] Fig. 4 is a flowchart showing a process related to suspension control according to the first embodiment. The process of this flowchart is repeatedly executed at predetermined time steps while the vehicle 1 is traveling. In Fig. 4, the process of step S100 corresponds to an example of the above-mentioned "first calculation process", the process of step S102 corresponds to an example of the above-mentioned "second calculation process", and the processes of steps S104, S108, and S110 correspond to an example of the above-mentioned "arbitration process".

[0045] <Step S100> In step S100, the ECU 10 calculates a first required control amount X1 for ride comfort control. The control law of the ride comfort control is not particularly limited, and therefore the calculation method of the first required control amount X1 is also not particularly limited. In this embodiment, it is assumed that preview control is executed as an example of ride comfort control. For this reason, the ECU 10 calculates the above-mentioned required control amount Xpv (target control force Fc_t) for the preview control as the first required control amount X1. The calculation of the first required control amount X1 is performed for each wheel 2 on which the actuator 3A is arranged.

[0046] In addition, for example, in an example in which multiple ride comfort controls (e.g., preview control and feedback control based on the above-mentioned skyhook control law) are being executed, the sum of the required control amounts of the multiple ride comfort controls being executed is calculated as the first required control amount X1.

[0047] <Step S102> In step S102, the ECU 10 calculates a second required control amount X2 for the attitude control. The control law of the attitude control is not particularly limited, and therefore the calculation method of the second required control amount X2 is also not particularly limited. In this embodiment in which roll control and pitch control are executed as the attitude control, the ECU 10 calculates the sum of the roll required control amount Xr and the pitch required control amount Xp as the second required control amount X2. The calculation of the second required control amount X2 is performed for each wheel 2 on which the actuator 3A is arranged.

[0048] Specifically, the roll required control amount Xr corresponds to a required value of the control force Fc required for roll control. The pitch required control amount Xp corresponds to a required value of the control force Fc required for pitch control. As an example, the roll required control amount Xr and the pitch required control amount Xp are expressed by the following equations (5) and (6), respectively. Xr = LA × Gr (5) Xp = FA × Gp (6)

[0049] As shown in equation (5), the roll required control amount Xr is given by the product of the lateral acceleration LA and the control gain Gr. As shown in equation (6), the pitch required control amount Xp is given by the product of the longitudinal acceleration FA and the control gain Gp. Note that the control gain Gr for roll control and the control gain Gp for pitch control may be the same or different. These control gains Gr and Gp correspond to the control gain G2 described below.

[0050] According to the roll request control amount Xr calculated by the formula (5), as the absolute value of the lateral acceleration LA increases, the absolute value of the roll request control amount Xr also increases. The control gain Gr is, for example, a fixed value determined in advance. However, the control gain Gr may be variable according to a parameter related to the vehicle attitude control. The lateral acceleration LA can be obtained, for example, by using a lateral acceleration sensor. The lateral acceleration LA may also be estimated based on information such as the vehicle speed V and the steering angle.

[0051] According to the pitch required control amount Xp calculated by the formula (6), the absolute value of the pitch required control amount Xp increases as the absolute value of the longitudinal acceleration FA increases. The control gain Gp is, for example, a fixed value determined in advance. However, the control gain Gp may be variable according to a parameter related to the vehicle attitude control. The longitudinal acceleration FA can be acquired, for example, by using a longitudinal acceleration sensor. Furthermore, the longitudinal acceleration FA may be estimated, for example, based on required information of the vehicle longitudinal force (for example, required engine torque or required braking force).

[0052] <Step S104> In step S104, the ECU 10 determines whether or not the total required control amount Xt, which is the sum of the first required control amount X1 and the second required control amount X2 calculated in steps S100 and S102, exceeds a control amount range Rx that can be output by the actuator 3A. This control amount range Rx can be specified in advance based on the specifications of the actuator 3A. If the required control amount Xt does not exceed the control amount range Rx, the process proceeds to step S106. On the other hand, if the required control amount Xt exceeds the control amount range Rx, the process proceeds to step S108.

[0053] <Step S106> If the determination result in step S104 is No (i.e., if the actuator 3A is capable of outputting the required control amount Xt), in step S106, the ECU 10 executes a process of commanding the required control amount Xt as is (i.e., without any restriction) to the actuator 3A for each wheel 2. As a result, each actuator 3A is controlled to generate a control force Fc according to the commanded required control amount Xt.

[0054] <Step S108> On the other hand, if the determination result in step S104 is Yes (i.e., the actuator 3A cannot output the required control amount Xt), in step S108, the ECU 10 calculates a road surface input index value I (also simply referred to as "index value I"). The index value I corresponds to an example of "road surface input information" according to the present disclosure.

[0055] Specifically, the index value I includes, for example, an index value Im indicating the magnitude of the road surface input, an index value Iv indicating the magnitude of the road surface input speed, and an index value If indicating the magnitude of the high-frequency component of the road surface input. The index value I calculated in this step S108 may be any one of these index values ​​Im, Iv, and If, or any two or three of them. Although the calculation method of each of the index values ​​Im, Iv, and If is not particularly limited, each of the index values ​​Im, Iv, and If can be calculated using, for example, the following method.

[0056] (Regarding the index value Im) More specifically, the magnitude of the road surface input corresponds to the magnitude of the unsprung displacement Zu or the magnitude of the road surface displacement Zr. Therefore, a specific example of the index value Im is a value indicating the magnitude of the unsprung displacement Zu or the road surface displacement Zr. When the preview control is performed as in this embodiment, the index value Im may be calculated based on the unsprung displacement Zu or the road surface displacement Zr acquired in the preview control. Alternatively, including the case where the preview control is executed, the unsprung displacement Zu used in the index value Im may be directly measured using an unsprung displacement sensor, or may be calculated (estimated) based on the measurement value of another sensor. The road surface displacement Zr used in the index value Im may be acquired, for example, by using an image captured by a camera mounted in front of the vehicle.

[0057] Also, for example, the pp value (peak to peak) or moving average value of the data (time, distance, or position-based data) of the unsprung displacement Zu or road surface displacement Zr in a predetermined data acquisition section along the vehicle travel direction may be calculated as the index value Im. Also, if the cutoff frequency of a low-pass filter (LPF) is made sufficiently small, the value after application of the LPF process can be regarded as a value equivalent to the moving average value. Therefore, the value after applying such an LPF to the data of the unsprung displacement Zu or road surface displacement Zr in the above data acquisition section may be calculated as the index value Im.

[0058] (Regarding the index value Iv) More specifically, the magnitude of the road surface input velocity corresponds to the magnitude of the unsprung velocity Zu' or the magnitude of the road surface deviation velocity Zr'. Therefore, a specific example of the index value Iv is a value indicating the magnitude of the unsprung velocity Zu' or the road surface deviation velocity Zr'. The calculation of the index value Iv based on the data of the unsprung velocity Zu' or the road surface deviation velocity Zr' can be performed using a method similar to the calculation method of the index value Im described above.

[0059] (Regarding the index value If) More specifically, the magnitude of the high-frequency component of the road surface input corresponds to the magnitude of the high-frequency component of the data of the unsprung displacement Zu or the road surface displacement Zr in a predetermined data acquisition section along the vehicle travel direction. Therefore, a specific example of the index value If is a value (e.g., signal strength) indicating the magnitude of the high-frequency component of the data of the unsprung displacement Zu or the road surface displacement Zr. The high-frequency component here is specified as, for example, a frequency component in a frequency range equal to or higher than a predetermined frequency value (predetermined cutoff frequency).

[0060] Such an index value If can be calculated based on a frequency spectrum acquired by performing a fast Fourier transform (FFT) process on the data of the unsprung displacement Zu or the road displacement Zr by the ECU 10. Alternatively, for example, a moving average value of output data after applying a band pass filter (BPF) process or a high pass filter (HPF) process to the data may be acquired as the index value If. In addition, a value after applying an LPF with a sufficiently small cutoff frequency to the output data may be acquired as the index value If.

[0061] (Use of the first required control amount X1) It can be said that the first required control amount X1 of the ride comfort control is basically calculated as a value corresponding to road surface input information, regardless of the calculation method. More specifically, the first required control amount X1 increases as the road surface input increases. As the road surface input speed increases, the rate of change of the first required control amount X1 also increases. Furthermore, as the high-frequency components of the road surface input increase, the high-frequency components of the first required control amount X1 also increase.

[0062] Therefore, data on the first required control amount X1 may be used instead of data on the unsprung displacement Zu or road surface displacement Zr to calculate the index value Im and If, respectively. Also, data on the first required control amount X1 may be used instead of data on the unsprung velocity Zu' or road surface displacement velocity Zr' to calculate the index value Iv.

[0063] <Step S110> In step S110, the ECU 10 calculates a limit value X2lmt, which is a second required control amount X2 after limitation based on the road surface input information (road surface input index value I). The index value I used to calculate the limit value X2lmt may be any one, or any two or three of the index values ​​Im, Iv, and If.

[0064] 5(A), 5(B), and 5(C) are diagrams for explaining an example of a calculation method of the limit value X2lmt based on the index values ​​Im, Iv, and If, respectively. The limit value X2lmt is calculated by correcting the control gain G2 of the posture control using the limit value G2lmt as follows. As a prerequisite for using the method shown in FIG. 5, it is assumed that the control gain G2 (Gr and Gp) is a fixed value. In an example in which the control gain G2 is varied based on a parameter related to the posture control, the ECU 10 may replace the vertical axis of FIG. 5 with a correction coefficient k1 (0≦k1≦1) and calculate the limit value G2lmt by multiplying the control gain G2 before correction by the correction coefficient k1.

[0065] In the calculation method described with reference to Fig. 5, the control gain G2 of the attitude control is corrected to a limit value G2lmt based on the road surface input information (index value I). When both the roll control and the pitch control are executed as the attitude control as in this embodiment, for example, each of the control gains Gr and Gp corresponding to the control gain G2 is corrected as described with reference to Fig. 5.

[0066] Specifically, in an example using the index value Im, as shown in Fig. 5(A), the limit value G2lmt is calculated so as to become smaller as the index value Im increases. As a result, the control gain G2 is corrected so as to become smaller as the index value Im increases (i.e., as the road surface input increases). In addition, although not shown in Fig. 5(A), the correction of the control gain G2 in response to an increase in the index value Im may include setting the limit value G2lmt to zero. The limit value G2lmt being zero means that the attitude control is stopped.

[0067] In the example using the index value Iv, as shown in Fig. 5(B), the limit value G2lmt is calculated so as to decrease as the index value Iv increases. As a result, the control gain G2 is corrected so as to decrease as the index value Iv increases (i.e., as the road surface input speed increases). As in the example using the index value Im, the correction of the control gain G2 in response to an increase in the index value Iv may include setting the limit value G2lmt to zero.

[0068] In an example using the index value If, ​​as shown in Fig. 5(C), the limit value G2lmt is calculated so as to decrease as the index value If increases. As a result, the control gain G2 is corrected so as to decrease as the index value If increases (i.e., as the high-frequency components of the road surface input increase). As in the example of the index values ​​Im and Iv, the correction of the control gain G2 in response to an increase in the index value If may include setting the limit value G2lmt to zero.

[0069] Next, two specific examples 1 and 2 of a method for calculating the limit value G2lmt in an example using a combination of two or three of the index values ​​Im, Iv, and If will be described. In the following description, a combination of the index value Im and the index value Iv will be exemplified, but the same applies to examples of other combinations of two or three.

[0070] In specific example 1, first, the reduction amount (limitation amount) of the control gain G2 based on each of the index values ​​Im and Iv is calculated using the relationship shown in Fig. 5(A) and 5(B). The reduction amount here means the reduction amount of the control gain G2 relative to the value before correction. Next, the two calculated reduction amounts are added together. Next, the limit value G2lmt is calculated by subtracting the summed reduction amount from the control gain G2 before correction. For example, if the reduction amount based on the index value Im reduces the control gain G2 by 20% and the reduction amount based on the index value Iv reduces the control gain G2 by 20%, the limit value G2lmt is calculated to be 40% less than the control gain G2 before correction.

[0071] Fig. 6 is a diagram for explaining a specific example 2 of a method for calculating the limit value G2lmt using a combination of a plurality of road surface input index values ​​I (e.g., Im and Iv). To implement the specific example 2, the storage device of the ECU 10 stores the relationship shown in Fig. 6 as a map. In the specific example 2, the index value Im and the index value Iv are compared with their respective threshold values ​​Imth1 and Ivth1.

[0072] As a result, when the index value Im is smaller than the threshold value Imth1 and the index value Iv is smaller than the threshold value Ivth1, the control gain G2 is not modified. In other words, it is determined that the ride comfort control does not need to be prioritized or is low, and the second required control amount X2 is not limited.

[0073] On the other hand, when only one of the index value Im and the index value Iv is equal to or greater than the corresponding threshold value Imth1 or Ivth1, the control gain G2 is corrected to be smaller according to the index value Im or index value Iv that is equal to or greater than the threshold value Imth1 or Ivth1 (using the relationship in FIG. 5(A) or 5(B)). In other words, it is determined that the situation is one in which ride comfort control should be prioritized, and the second required control amount X2 is restricted.

[0074] Furthermore, when the index value Im is equal to or greater than the threshold value Imth1 and the index value Iv is equal to or greater than the threshold value Ivth1, the control gain G2 is modified to be smaller than when only one of the index value Im and the index value Iv is equal to or greater than the corresponding threshold value Imth1 or Ivth1. In other words, it is determined that the situation requires higher priority to be given to ride comfort control, and the second required control amount X2 is restricted to a greater extent.

[0075] According to each of the specific examples 1 and 2, the limit value X2lmt is calculated by taking into account two or more of the index values ​​Im, Iv, and If, so that the road surface input information can be taken into account more accurately. As a result, the second required control amount X2 can be restricted (adjusted) more accurately.

[0076] <Step S112> In step S112, the ECU 10 calculates a final required control amount Xfin for the suspension control. The required control amount Xfin is the sum of the first required control amount X1 and the limit value X2lmt calculated in steps S100 and S110, respectively.

[0077] <Step S114> In step S114, the ECU 10 executes a process of commanding the actuator 3A the required control amount Xfin calculated in step S112 for each wheel 2. As a result, each actuator 3A is controlled to generate a control force Fc according to the commanded required control amount Xfin.

[0078] 1-3.Effects The output of the actuator 3A for performing suspension control is limited. Therefore, even if the actuator 3A is commanded to simply add up the required control amounts X1 and X2 for both the ride comfort control and the attitude control under conditions in which the actuator 3A cannot output the sum of these control amounts X1 and X2, the control of one of the controls that should be prioritized cannot be appropriately performed, and the suspension control suited to the situation may not be performed satisfactorily. Moreover, if only one of the controls is selected under the conditions, the other control cannot be performed, and therefore the suspension control suited to the situation may not be performed satisfactorily.

[0079] In contrast, according to the arbitration process of the first embodiment, when the sum (requested control amount Xt) of the first required control amount X1 and the second required control amount X2 exceeds the control amount range Rx, the second required control amount X2 for the posture control is limited to a small value by the limit value X2lmt based on the road surface input information (road surface input index value I). That is, in such a case, the ride comfort control is prioritized over the posture control. In addition, no change is made to limit the ride comfort control. As a result, under conditions in which the actuator 3A cannot satisfy both the required control amounts X1 and X2 of the ride comfort control and the posture control, the ride comfort control can be performed well while appropriately limiting the posture control in consideration of the road surface input information. That is, it becomes possible to achieve both the ride comfort control and the posture control while considering the road surface condition. As a result, the comfort of the vehicle 1 can be improved by using the suspension control, compared to a case in which the required control amounts X1 and X2 are simply added together and instructed to the actuator 3A under the conditions, or only one of the controls is selected.

[0080] More specifically, when the road surface input is large, a higher output is required for ride comfort control compared to when the road surface input is small. According to the first embodiment, the control gain G2 is calculated so that it decreases as the index value Im increases. By adjusting the control gain G2 in this manner, it becomes possible to appropriately limit the posture control in consideration of the road surface condition (in other words, it becomes possible to appropriately prioritize the ride comfort control) so that the second required control amount X2 for posture control decreases as the road surface input increases.

[0081] Furthermore, when the road surface input speed is high, higher responsiveness is required for the ride comfort control compared to when the road surface input speed is low. According to the first embodiment, the control gain G2 is calculated so that it decreases as the index value Iv increases. By adjusting the control gain G2 in this manner, it becomes possible to appropriately limit the posture control in consideration of the road surface condition (in other words, it becomes possible to appropriately prioritize the ride comfort control) so that the second required control amount X2 for the posture control decreases as the road surface input speed increases. In addition, when the output of the actuator 3A secured for the ride comfort control increases, the actuator 3A becomes able to generate an output (control force Fc) with high responsiveness.

[0082] Furthermore, when the high-frequency components of the road surface input are large, higher responsiveness is required for the ride comfort control compared to when the high-frequency components are small. According to the first embodiment, the control gain G2 is calculated so that it decreases as the index value Iv increases. By adjusting the control gain G2 in this manner, it becomes possible to appropriately limit the posture control in consideration of the road surface condition (in other words, it becomes possible to appropriately prioritize the ride comfort control) so that the second required control amount X2 for the posture control decreases as the high-frequency components of the road surface input increase.

[0083] 1-4. Restrictions based on suspension spring characteristics The second required control amount X2 according to the first embodiment may be limited in consideration of the spring characteristics of the suspension 3 as well as the road surface input information.

[0084] FIG. 7 is a diagram showing the spring characteristics of the suspension 3 shown in FIG. 2. More specifically, FIG. 7 shows the load-stroke characteristics of the suspension 3. The stroke ST1 in FIG. 7 corresponds to the value of the stroke ST when the vehicle 1 is stationary (i.e., when the gravitational acceleration acting on the vehicle body 6 is 1G). For example, in the case of the outer wheel during turning, if the stroke ST changes so that the bump stop clearance decreases with an increase in the lateral acceleration LA, the damper 3D (its case) will eventually come into contact with the bump rubber 3B. The stroke ST2 corresponds to the value of the stroke ST when the case starts to come into contact with the bump rubber 3B.

[0085] In the spring characteristics shown in FIG. 7, the stroke region from stroke ST1 to stroke ST2 corresponds to a linear region (a region in which the spring 3S generates a spring force) in which the load increases in proportion to the stroke ST. Not only the spring 3S but also the bump rubber 3B functions as a spring. Therefore, in the spring characteristics shown in FIG. 7, the stroke region larger than stroke ST2 corresponds to a nonlinear region in which the spring constant changes according to the stroke ST. In this nonlinear region, the load changes more greatly with respect to changes in stroke ST than in the linear region.

[0086] When the suspension 3 strokes into the nonlinear region, the ride comfort deteriorates. In order to avoid such deterioration of the ride comfort, it is desirable to secure sufficient output of the actuator 3A for posture control (roll control and pitch control) so that the damper 3D does not come into contact with the bump rubber 3B. However, increasing the output secured for posture control leads to a decrease in the output secured for ride comfort control. In other words, it becomes difficult for the actuator 3A to exert sufficient output and responsiveness for ride comfort control.

[0087] (First example) Therefore, in a first example of a restriction based on the spring characteristic, when the above-mentioned index value Im (magnitude of road surface input) is equal to or greater than a predetermined threshold value Imth2, the ECU 10 restricts the second required control amount X2 to a small value based on the spring characteristic of the suspension 3. Specifically, as an example of a restriction on the second required control amount X2 based on the spring characteristic, the ECU 10 changes the control gain G2 so that the roll angle associated with steering and the pitch angle associated with acceleration / deceleration become zero.

[0088] 8 is a flowchart showing a process related to a first example of suspension control related to a restriction based on a suspension spring characteristic. The process of this flowchart differs from the process of the flowchart shown in FIG. 4 in that the processes of steps S200 and S202 are executed as an "arbitration process" instead of the processes of steps S108 and S110.

[0089] In FIG. 8, when the determination result in step S104 is Yes, in step S200, the ECU 10 determines whether the index value Im is equal to or greater than a predetermined threshold value Imth2.

[0090] If the determination result in step S200 is No (i.e., if the road surface input is small and therefore ride comfort control does not need to be prioritized over attitude control), the ECU 10 executes the process of step S106 described above. That is, in this case, even if the determination result in step S104 is Yes, the second required control amount X2 is not limited. As a result, in response to a command for a required control amount Xt that exceeds the control amount range Rx, the actuator 3A is controlled to generate an output (control force Fc) equivalent to the maximum value of the control amount range Rx.

[0091] On the other hand, if the determination result in step S200 is Yes (that is, if the road surface input is large and therefore ride comfort control needs to be prioritized over attitude control), the process proceeds to step S202.

[0092] In step S202, the ECU 10 changes the control gains G2 (Gr and Gp) so that the roll angle associated with steering and the pitch angle associated with acceleration / deceleration become zero. Here, the control gain Gr0 required to make the roll angle zero can be specified in advance in association with the lateral acceleration LA. The storage device of the ECU 10 stores a map that defines the relationship between the control gain Gr0 and the lateral acceleration LA. In this step S200, the ECU 10 calculates the control gain Gr0 for making the roll angle zero under the current lateral acceleration LA from such a map. Similarly, for the control gain Gp0 required to make the pitch angle zero, the ECU 10 calculates the control gain Gp0 for making the pitch angle zero under the current longitudinal acceleration FA from the map that defines the relationship between the control gain Gp0 and the longitudinal acceleration FA. The control gains Gr0 and Gp0 calculated in this way correspond to the above-mentioned limit value G2lmt.

[0093] Then, in step S202, the ECU 10 calculates the sum of the roll required control amount Xr0 and the pitch required control amount Xp0, which are calculated by substituting the control gains Gr0 and Gp0 into the above-mentioned equations (5) and (6), respectively, as the limit value X2lmt of the second required control amount X2.

[0094] According to the first example described with reference to FIG. 8, when the road surface input is large (index value Im≧threshold Imth2), posture control is executed so that the roll angle becomes zero and the pitch angle becomes zero by changing the control gain G2. According to the posture control executed in this way, the second required control amount X2 is limited compared to when the road surface input is small (index value Im<threshold Imth2) and posture control is executed as it is so that roll and pitch in the opposite directions occur. Also, compared to an example in which roll control and pitch control are not executed as much as possible or are stopped because the road surface input is large, it is possible to suppress the deterioration of ride comfort caused by contact between the damper 3D and the bump rubber 3B. And, contact between the damper 3D and the bump rubber 3B is least likely to occur in such a state in which the roll angle and pitch angle are maintained at zero. Therefore, by performing posture control so as to obtain the above state when the road surface input is large, it is possible to suppress the deterioration of ride comfort caused by contact of the bump rubber 3B while limiting the output of the actuator 3A secured for posture control, and it is possible to secure a large output of the actuator 3A for ride comfort control.

[0095] In the flowchart shown in Fig. 8, this first example (an example in which posture control is performed so that the roll angle and pitch angle become zero by changing the control gain G2 when the road surface input is large) is performed when the determination result in step S104 is Yes (when the required control amount Xt exceeds the control amount range Rx). However, unlike the processing in the flowchart shown in Fig. 8, the first example may be performed in order to avoid a deterioration in ride comfort caused by contact of the bump rubber 3B accompanying the execution of ride comfort control due to a large road surface input, even when the required control amount Xt falls within the control amount range Rx (i.e., under a situation in which the output and responsiveness of the actuator 3A are sufficient).

[0096] (Second example) In a second example of a restriction based on spring characteristics, when the index value Im (magnitude of road surface input) is equal to or greater than the threshold value Imth2, the ECU 10 restricts the second required control amount X2 to a small amount based on the spring characteristics of the suspension 3 by the following method. That is, the restriction value X2lmt is determined by utilizing the correction of the control gain G2 so that contact of the bump rubber 3B does not occur when the actuator 3A is commanded to receive the final required control amount Xfin, which is the sum of the first required control amount X1 for ride comfort control and the restriction value X2lmt for posture control.

[0097] Specifically, for example, when the current bump stop clearance is 30 mm and the road input (road displacement Zr) is 20 mm, the amount of stroke ST to be controlled by ride comfort control such as preview control is 20 mm, which is equal to the road input. Therefore, the amount of stroke ST available for posture control while avoiding contact with the bump rubber 3B is less than 10 mm, which is the difference between the bump stop clearance and the amount of stroke ST. In the second example, the limit value X2lmt is calculated using a control gain G2 that is corrected so that the amount of stroke ST by posture control is less than 10 mm.

[0098] In addition, the current bump stop clearance can be calculated (estimated) using, for example, the following method. That is, the stroke ST1 in the stationary state of the vehicle 1 is known. Taking roll as an example, when turning from a stationary state (a state in which the roll angle is zero), the change in the roll angle in the absence of roll control can be grasped in advance based on the lateral acceleration LA. Therefore, the change in the stroke ST corresponding to this roll angle change (i.e., the change in the bump stop clearance) can also be estimated from the lateral acceleration LA. In addition, the change in the roll angle due to the roll control and the change in the bump stop clearance associated therewith can be estimated from the most recent roll required control amount Xr. Therefore, using these estimation results, the bump stop clearance that changes due to the execution of the roll control can be estimated. Also, based on the same idea, the bump stop clearance that changes due to the execution of the pitch control can also be estimated. Then, by adding up the estimated values ​​of these two bump stop clearances, the bump stop clearance during the execution of both the roll control and the pitch control can be estimated.

[0099] This second example also makes it possible to suppress the deterioration of ride comfort caused by contact with the bump rubber 3B while limiting the output of the actuator 3A secured for posture control, and also makes it possible to secure a large output of the actuator 3A for ride comfort control.

[0100] Furthermore, not limited to the combination of the spring 3S and the bump rubber 3B, even when a nonlinear spring is used as the spring 3S, a spring characteristic in which the spring constant changes with the change in the stroke ST can be obtained, such as the linear region and the nonlinear region as shown in Fig. 7. Therefore, the above-mentioned first and second examples may be implemented for a suspension using such a nonlinear spring, in order to avoid using the stroke range in which the spring constant becomes high.

[0101] 2. Second embodiment In the arbitration process in the above-described first embodiment, the second required control amount X2 is limited to a small amount based on the road surface input information. In contrast, in the arbitration process in the second embodiment, the first required control amount X1 is limited to a small amount based on at least one of the vehicle operation information and the vehicle motion information in order to achieve both the ride comfort control and the attitude control while taking into account at least one of the vehicle operation state and the vehicle motion state.

[0102] The "vehicle operation information" here refers to information related to the operation of the vehicle 1, such as at least one of the steering amount of the steering wheel, the steering speed, the accelerator pedal depression amount, the accelerator pedal depression speed, the brake pedal depression amount, and the brake pedal depression speed. The "vehicle motion information" refers to information related to the motion of the vehicle 1, such as at least one of the lateral acceleration LA, the lateral jerk, the yaw rate, the longitudinal acceleration FA, the longitudinal jerk, and the vehicle speed V.

[0103] Fig. 9 is a flowchart showing a process related to suspension control according to embodiment 2. The process of this flowchart differs from the process of the flowchart shown in Fig. 4 in that the processes of steps S300, S302, and S304 are executed instead of the processes of steps S108, S110, and S112.

[0104] <Step S300> 9, if the determination result in step S104 is Yes (i.e., if the actuator 3A cannot output the required control amount Xt), the process proceeds to step S300. In step S300, the ECU 10 calculates a priority P which is an index value indicating the priority of the posture control relative to the ride comfort control side.

[0105] The priority P is calculated based on the vehicle operation information. Specifically, for example, the priority P is calculated so that the priority P is higher as the steering amount of the steering wheel is larger. The priority P may be calculated so that the priority P is higher as the steering speed is higher (i.e., when sudden steering is performed). The priority P may also be calculated so that the priority P is higher as the accelerator pedal depression amount is larger, or the accelerator pedal depression speed is higher (i.e., when sudden acceleration is performed). Similarly, the priority P may be calculated so that the priority P is higher as the brake pedal depression amount is larger, or the brake pedal depression speed is higher (i.e., when sudden deceleration is performed). Alternatively, the priority P may be calculated so that the priority P is higher as multiple parameters among these parameters included in the vehicle operation information are larger.

[0106] The priority P may also be calculated based on the vehicle motion information. Specifically, for example, the priority P may be calculated so that it is higher as the lateral acceleration LA is higher. Similarly, the priority P may be calculated so that it is higher as any one of the lateral jerk, the yaw rate, the longitudinal acceleration FA, the longitudinal jerk, and the vehicle speed V is higher. Alternatively, the priority P may be calculated so that it is higher as more than one of these parameters included in the vehicle motion information is larger.

[0107] Moreover, the priority P may be calculated based on both the vehicle operation information and the vehicle motion information described above.

[0108] In addition, the priority of posture control over ride comfort control is required when the output (control force Fc) of actuator 3A required to realize first required control amount X1 of posture control becomes large. The priority P calculated as described above is calculated to be high when the vehicle operation information or vehicle motion information is changing so that the output of actuator 3A required to realize first required control amount X1 becomes large, for example, when the steering speed is high (when sudden steering is performed) and when the lateral acceleration LA is high.

[0109] <Step S302> In step S302, the ECU 10 calculates a limit value X1lmt that is the first required control amount X1 after limitation based on the priority P (at least one of the vehicle operation information and the vehicle motion information).

[0110] Fig. 10 is a diagram for explaining an example of a calculation method of the limit value X1lmt based on the priority P. The limit value X1lmt is calculated by correcting the control gain G1 of the ride comfort control using the limit value G1lmt as follows. As a prerequisite for using the method shown in Fig. 10, the control gain G1 (for example, the above-mentioned control gains α and β) is a fixed value. In an example in which the control gain G1 is varied based on a parameter related to the ride comfort control, the ECU 10 may replace the vertical axis of Fig. 10 with a correction coefficient k2 (0 ≦ k2 ≦ 1) and calculate the limit value G1lmt by multiplying the control gain G1 before correction by the correction coefficient k2.

[0111] In an example shown in FIG. 10, when the priority P is equal to or less than a predetermined threshold value Pth, the limit value G1lmt is calculated as a value equal to the control gain G1 before correction. That is, in this case, the control gain G1 is not corrected. On the other hand, when the priority P exceeds the threshold value Pth, the limit value G1lmt is calculated so that it becomes smaller as the priority P becomes higher. As a result, the control gain G1 is corrected so that it becomes smaller as the priority P becomes higher. In addition, although not shown in FIG. 10, the correction of the control gain G1 in response to an increase in the priority P may include setting the limit value G1lmt to zero. The limit value G1lmt being zero means that the ride comfort control is stopped.

[0112] <Step S304> In step S304, the ECU 10 calculates a final required control amount Xfin for the suspension control. The required control amount Xfin is the sum of the limit value X1lmt and the second required control amount X2 calculated in steps S302 and S102, respectively.

[0113] According to the arbitration process according to the second embodiment described above, when the sum of the first required control amount X1 and the second required control amount X2 (required control amount Xt) exceeds the control amount range Rx, the first required control amount X1 for the ride comfort control is limited to a small value by the limit value X1lmt based on the priority P (at least one of the vehicle operation information and the vehicle motion information). That is, in such a case, the posture control is prioritized over the ride comfort control. In addition, no change is made to limit the posture control. As a result, under a condition in which the actuator 3A cannot satisfy both the required control amounts X1 and X2 of the ride comfort control and the posture control, the posture control can be performed well while appropriately limiting the ride comfort control by considering at least one of the vehicle operation information and the vehicle motion information. That is, it becomes possible to achieve both the ride comfort control and the posture control while considering at least one of the vehicle operation information and the vehicle motion information. As a result, the comfort of the vehicle 1 can be improved by using the suspension control, compared to a case in which the required control amounts X1 and X2 are simply added together and instructed to the actuator 3A under the condition, or only one of the controls is selected.

[0114] More specifically, as described above, when the priority P is high, a higher output is required for posture control compared to when the priority P is low. According to the second embodiment, the control gain G1 is calculated so as to be smaller as the priority P is higher. By adjusting the control gain G1 in this manner, it becomes possible to appropriately limit the ride comfort control in consideration of at least one of the vehicle operation information and the vehicle motion information so that the first required control amount X1 for the ride comfort control becomes smaller as the priority P is higher (in other words, it becomes possible to appropriately prioritize the posture control).

[0115] 3. Other embodiments In the above-described first and second embodiments, the ride comfort control and the attitude control are performed on the four wheels 2 (i.e., all wheels) of the vehicle 1. However, the wheels (control target wheels) that are the targets of the ride comfort control and the attitude control are not necessarily limited to all wheels, and may be, for example, only the left and right front wheels or only the left and right rear wheels.

[0116] Furthermore, the arbitration process according to the first embodiment and the arbitration process according to the second embodiment may be executed in combination. [Explanation of symbols]

[0117] 1 vehicle 2 wheels 3. Suspension 3A Actuator 3B Bumper rubber 3D Damper 3S Spring 4. Unsprung structure 5. Spring structure 6. Body 10 Electronic Control Unit (ECU) 12 Sensors 14 Communication equipment

Claims

1. An actuator for controlling the suspension stroke of a controlled wheel; An electronic control unit; A vehicle suspension control device comprising: The electronic control unit includes: a first calculation process for calculating a first required control amount for ride comfort control in response to a road surface input; a second calculation process for calculating a second required control amount for posture control in response to a vehicle operation input; an arbitration process for limiting the second required control amount to a smaller amount based on road surface input information when a sum of the first required control amount and the second required control amount exceeds a control amount range that can be output by the actuator; Run In the arbitration process, the electronic control unit reduces the control gain included in the second required control amount as the road surface input included in the road surface input information increases. A vehicle suspension control device comprising:

2. An actuator for controlling the suspension stroke of a controlled wheel; An electronic control unit; A vehicle suspension control device comprising: The electronic control unit includes: a first calculation process for calculating a first required control amount for ride comfort control in response to a road surface input; a second calculation process for calculating a second required control amount for posture control in response to a vehicle operation input; an arbitration process for limiting the second required control amount to a smaller amount based on road surface input information when a sum of the first required control amount and the second required control amount exceeds a control amount range that can be output by the actuator; Run In the arbitration process, the electronic control unit reduces the control gain included in the second required control amount as the road surface input speed included in the road surface input information increases. A vehicle suspension control device comprising:

3. An actuator for controlling the suspension stroke of a controlled wheel; An electronic control unit; A vehicle suspension control device comprising: The electronic control unit includes: a first calculation process for calculating a first required control amount for ride comfort control in response to a road surface input; a second calculation process for calculating a second required control amount for posture control in response to a vehicle operation input; an arbitration process for limiting the second required control amount to a smaller amount based on road surface input information when a sum of the first required control amount and the second required control amount exceeds a control amount range that can be output by the actuator; Run In the arbitration process, the electronic control unit reduces the control gain included in the second required control amount as the high frequency component of the road surface input included in the road surface input information becomes larger. A vehicle suspension control device comprising:

4. An actuator for controlling the suspension stroke of a controlled wheel; An electronic control unit; A vehicle suspension control device comprising: The electronic control unit includes: a first calculation process for calculating a first required control amount for ride comfort control in response to a road surface input; a second calculation process for calculating a second required control amount for posture control in response to a vehicle operation input; an arbitration process for limiting the second required control amount to a smaller amount based on road surface input information when a sum of the first required control amount and the second required control amount exceeds a control amount range that can be output by the actuator; Run In the arbitration process, when the road surface input included in the road surface input information is equal to or greater than a threshold value, the electronic control unit limits the second required control amount to a small value based on a suspension spring characteristic. A vehicle suspension control device comprising:

5. the attitude control includes at least one of roll control and pitch control, The limiting of the second required control amount based on the suspension spring characteristic includes changing a control gain included in the second required control amount so that at least one of a roll angle and a pitch angle becomes zero.

5. The vehicle suspension control device according to claim 4.

6. An actuator for controlling the suspension stroke of a controlled wheel; An electronic control unit; A vehicle suspension control device comprising: The electronic control unit includes: a first calculation process for calculating a first required control amount for ride comfort control in response to a road surface input; a second calculation process for calculating a second required control amount for posture control in response to a vehicle operation input; an arbitration process for limiting the first required control amount to a small amount based on at least one of vehicle operation information and vehicle motion information when a sum of the first required control amount and the second required control amount exceeds a control amount range that can be output by the actuator; Run In the arbitration process, the electronic control unit reduces a control gain included in the first required control amount as the priority of the posture control relative to the ride comfort control, which is an index based on at least one of the vehicle operation information and the vehicle motion information, is higher. A vehicle suspension control device comprising:

Images