Vehicle behavior control device

Abstract

The present invention relates to a behavior control device for a vehicle, which is capable of suppressing variations in roll rigidity distribution in consideration of suppression of a large roll according to lateral acceleration or a state of vehicle stability control, and is provided with a roll rigidity variable device and a controller. The roll rigidity variable device is configured so as to vary the roll rigidity of a first shaft, which is one of a front shaft and a rear shaft of a vehicle, and the roll rigidity of a second shaft, which is the other of the front shaft and the rear shaft. In at least a low acceleration region among regions of lateral acceleration acting on the vehicle, the controller controls the roll rigidity variable device so that the roll rigidity of the first shaft increases in accordance with an increase in the lateral acceleration. In addition, when the lateral acceleration exceeds the low acceleration range and increases to the high acceleration range or when there is an abnormality in vehicle stability control for suppressing at least one of oversteering and understeering of the vehicle. The controller executes a control process for controlling the roll rigidity variable device so as to increase the roll rigidity of the second shaft.

Description

Technical Field

[0001] The present disclosure relates to a behavior control device for a vehicle. Background Art

[0002] Patent document 1 discloses a roll control device for a vehicle. The roll control device increases the control amount of the actuators on both sides of the first axis and the second axis (rear axis and front axis) in a manner that increases the roll rigidity of the first axis and the second axis (rear axis and front axis) according to the increase in lateral acceleration. Furthermore, when the lateral acceleration exceeds the low acceleration region and increases to the high acceleration region, the roll control device reduces the gain of the control amount of the actuator on the first axis side relative to the lateral acceleration in accordance with the increase in lateral acceleration in a manner that the roll rigidity distribution rate of the first axis does not exceed a prescribed value.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2023-051026

[0004] According to the technology described in Patent Document 1, it is possible to suppress the deviation of roll stiffness distribution in the high acceleration region and suppress the occurrence of undesired oversteer or understeer. However, in the method of reducing the roll control gain, a large roll is likely to occur in the high acceleration region. In addition, in the case where the vehicle stability control is abnormal even when the lateral acceleration is low, the deviation of roll stiffness distribution may become an important factor that easily causes undesired oversteer or understeer, for example, depending on the road conditions. Summary of the invention

[0005] The present disclosure has been made in view of the above-mentioned problems, and an object of the present disclosure is to provide a vehicle behavior control device capable of suppressing a deviation in roll stiffness distribution in consideration of suppression of a large roll corresponding to a lateral acceleration or a state of vehicle stability control.

[0006] The vehicle behavior control device involved in the present disclosure includes a variable roll stiffness device and a controller. The variable roll stiffness device is configured to make the roll stiffness of a first axis, which is one of the front and rear axes of the vehicle, and the roll stiffness of a second axis, which is the other of the front and rear axes, variable. In at least a low acceleration region in the region of lateral acceleration acting on the vehicle, the controller controls the variable roll stiffness device in a manner that increases the roll stiffness of the first axis in accordance with the increase in lateral acceleration. In addition, in a case where the lateral acceleration exceeds the low acceleration region and increases to the high acceleration region, or in a case where there is an abnormality in the vehicle stability control of at least one of suppressing oversteering and understeering of the vehicle, the controller performs a control process to control the variable roll stiffness device in a manner that increases the roll stiffness of the second axis.

[0007] According to the present disclosure, when the acceleration exceeds the low acceleration region and increases to the high acceleration region, the deviation of the roll stiffness distribution can be suppressed regardless of the method of reducing the roll control gain (i.e., suppressing the generation of a large roll corresponding to the lateral acceleration). In addition, according to the present disclosure, when there is an abnormality in the vehicle stability control, even in the low acceleration region, it is possible to suppress undesired oversteering or understeering by suppressing the deviation of the roll stiffness distribution caused by the execution of the control process. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a diagram showing the configuration of a vehicle equipped with the behavior control device according to the embodiment.

[0009] Figure 2 It is a diagram schematically showing a basic configuration of roll control according to the embodiment.

[0010] Figure 3 This is a flowchart showing an example of a process related to the roll control including a control process according to the embodiment.

[0011] Figure 4 This is a diagram for explaining a specific example EX3 of the allocation process. DETAILED DESCRIPTION

[0012] 1. Vehicle behavior control device

[0013] Figure 1 1 is a diagram showing the structure of a vehicle 10 equipped with a behavior control device according to an embodiment. Figure 1 As shown, the vehicle 10 includes a left front wheel 14FL and a right front wheel 14FR on a front axle 16F, and a left rear wheel 14RL and a right rear wheel 14RR on a rear axle 16R as four wheels 14. In the vehicle 10, for example, the left and right wheels 14FL and 14FR are steering wheels.

[0014] The vehicle 10 includes suspensions 20FL, 20FRA, 20RLA, and 20RRA. The suspensions 20FL, 20FRA, 20RLA, and 20RRA suspend a left front wheel 14FL, a right front wheel 14FR, a left rear wheel 14RL, and a right rear wheel 14RR from the vehicle body 12, respectively.

[0015] The suspension 20FL of the left front wheel 14FL is a non-active suspension, and includes a spring 22FL and a shock absorber 24FL.

[0016] The suspension 20FRA of the right front wheel 14FR is an active suspension (full active suspension), and includes an actuator 26FR in addition to a spring 22FR and a shock absorber 24FR. The actuator 26FR is configured to actively apply a control force in the up-and-down direction between the vehicle body 12 and the right front wheel 14FR. The actuator 26FR is, for example, an electric or hydraulic type.

[0017] The suspensions 20RLA and 20RRA of the rear axle 16R are also active suspensions, and are respectively provided with actuators 26RL and 26RR in addition to springs 22RL and 22RR and shock absorbers 24RL and 24RR. The actuators 26RL and 26RR are respectively configured to actively apply control forces in the up-and-down directions between the vehicle body 12 and the left and right wheels 14RL and 14RR of the rear axle 16R. The actuators 26RL and 26RR are, for example, electric or hydraulic.

[0018] The vehicle 10 is equipped with a controller 30. The controller 30 obtains signals from a sensor group 40 installed in the vehicle 10. The sensor group 40 includes sensors such as an acceleration sensor, a vehicle height sensor, a sprung acceleration sensor, and a wheel speed sensor that measure physical quantities related to the behavior of the vehicle 10. In addition, the controller 30 controls the actuators 26FR, 26RL, and 26RR.

[0019] The controller 30 includes a processor 32 and a memory 34 coupled to the processor 32. The processor 32 executes various processes related to the behavior control of the vehicle 10. The behavior control includes at least the roll control described later. The memory 34 stores various information required for the execution of various processes involved in the processor 32. For example, the memory 34 stores a program 36 executable by the processor 32 and various information related to the program 36. The behavior control is achieved by the execution of the program 36 by the processor 32.

[0020] In addition, various processes related to the behavior control of the vehicle 10 may include the following processes related to vehicle stability control. Vehicle stability control is a control to suppress at least one of oversteering and understeering of the vehicle 10. The vehicle stability control includes, for example, controlling at least one of a driving device and a braking device of the vehicle 10 in such a way that the controller 30 detects the sideslip of the vehicle 10 using the sensor group 40 and suppresses the sideslip. The driving device is, for example, at least one of an electric motor and an internal combustion engine.

[0021] 2. Vehicle roll control

[0022] In the present embodiment, the rear axle 16R corresponds to the "first axle" and the front axle 16F corresponds to the "second axle". The pair of left and right active suspensions 20RLA and 20RRA of the rear axle 16R and the single active suspension 20FRA of the front axle 16F function as a "roll stiffness variable device" that makes the roll stiffness of the rear axle 16R and the roll stiffness of the front axle 16F variable. In addition, the "behavior control device" according to the present embodiment is configured to include a roll stiffness variable device and a controller 30. The roll control according to the present embodiment is performed by the controller 30 that controls the roll stiffness variable device.

[0023] first, Figure 2 It is a diagram schematically showing a basic configuration of roll control according to the embodiment. Figure 2 The modeled vehicle 10 and the lateral acceleration (lateral G) acting on the center of gravity 11 of the vehicle 10 are shown in FIG. y , the control force F applied by the variable roll stiffness device for roll suppression rl and F rr .exist Figure 2 The left side shows the lateral acceleration a y Low state, the lateral acceleration a is shown on the right y Increased state. In addition, Figure 2 The lateral acceleration a is shown in y A graph showing changes in the roll rigidity distribution ratio of the front axle 16F and the rear axle 16R before and after enlargement.

[0024] have Figure 1 as well as Figure 2 The basic structure of the roll control in the vehicle 10 having the suspension structure shown is as follows. That is, on the rear axle 16R side where both the left and right wheels 14RL and 14RR have active suspensions 20RLA and 20RRA, the actuators 26RL and 26RR generate F rl and F rr In more detail, Figure 2 As shown, for example, when a lateral acceleration a in the right direction acts on the vehicle 10 y In the case of the left rear wheel 14RL, the actuator 26RL applies a downward control force F rl , and the actuator 26RR applies an upward control force F to the right rear wheel 14RR rr Thus, in the vehicle 10 having the above suspension structure, no heave or pitch occurs, and the lateral acceleration a can be suppressed. y In other words, the rolling moment caused by the lateral acceleration a y The roll rigidity of the rear axle 16R (first axle) is increased.

[0025] According to the basic configuration of the roll control, the details of which will be described later, the control forces F applied to the left and right wheels 14RL and 14RR are rl and F rr According to the lateral acceleration a y That is, the roll stiffness variable device is controlled by the controller 30 to increase according to the lateral acceleration a y The increase in the roll rigidity of the rear axle 16R increases. Figure 2 In the figure, a represents the lateral acceleration. y The length of the arrow in the direction of represents the lateral acceleration a y The size of the control force F rl and F rr The lengths of the arrows in the directions of rl and F rr size.

[0026] According to the basic structure of roll control, such as Figure 2 As shown, according to the lateral acceleration a y The roll rigidity of the rear axle 16R is increased by the increase of the lateral acceleration a, and the roll rigidity distribution rate of the rear axle 16R gradually increases. y As the lateral acceleration increases, the deviation of the roll stiffness distribution rate increases. y In this regard, by reducing the roll control gain in the high acceleration region, the occurrence of unwanted oversteer or understeer can be suppressed. However, in this method, a large roll is easily generated in the high acceleration region. In addition, it is preferable to take measures to suppress the deviation of the roll stiffness distribution in consideration of the state of the vehicle stability control.

[0027] In view of this, regarding the roll control involved in this embodiment, the process executed by the controller 30 includes a “control process”. In the control process, the controller 30 y When the acceleration exceeds the low acceleration region R1 and increases to the high acceleration region R2, or when there is an abnormality in the "vehicle stability control", the roll stiffness variable device is controlled so as to increase the roll stiffness of the front axle 16F (second axle).

[0028] Figure 3 1 is a flowchart showing an example of a process related to the roll control including a control process according to the embodiment. The process of this flowchart is repeatedly executed by the controller 30 (processor 32) while the vehicle 10 is traveling.

[0029] <Step S100>

[0030] First, in step S100, the controller 30 uses the sensor group 40 to obtain the lateral acceleration a y Specifically, the lateral acceleration a y For example, it is an estimated value estimated from the steering angle and vehicle speed. y The method of obtaining the lateral acceleration a is not particularly limited. y For example, it may be a sensor value measured by an acceleration sensor.

[0031] <Step S102>

[0032] Next, in step S102, the controller 30 calculates the lateral acceleration a obtained in step S100. y Is it the specified threshold a? yt That is, the lateral acceleration a is determined. y Whether it is in the high acceleration region R2 or in the low acceleration region R1.

[0033] More specifically, the high acceleration region R2 corresponds to an acceleration region near the turning limit of the vehicle 10. Therefore, the lateral acceleration a y Less than threshold a yt (i.e., being in the low acceleration region R1) means that there is a margin relative to the turning limit. When there is this margin, undesirable oversteering or understeering, or large roll, will not occur. Therefore, in step S102, it is determined that the lateral acceleration a y The margin relative to the turning limit. For example, if the lateral acceleration is a y is the threshold value a yt In the case of the above (i.e., in the high acceleration region R2), it is determined that the margin relative to the turning limit is small. In addition, when the estimated friction coefficient of the road surface on which the vehicle 10 is traveling can be calculated, in order to determine the margin relative to the limit lateral acceleration corresponding to the estimated friction coefficient, the threshold value a may be determined in consideration of the estimated friction coefficient. yt .

[0034] <Step S104>

[0035] At the lateral acceleration a y Less than threshold a yt In the case of (step S102; No), the controller 30 determines in step S104 whether there is an abnormality in the vehicle stability control. The method for determining the abnormality is not particularly limited, and any known determination method can be used.

[0036] <Step S106>

[0037] If the result of determination in step S104 is "No" (i.e., the lateral acceleration ay Less than threshold a yt , and the vehicle stability control is normal), the process proceeds to step S106. Hereinafter, the process proceeding to step S106 in this way is referred to as "normal time".

[0038] In step S106, the controller 30 calculates the required control force F for each wheel (that is, the four wheels including the left front wheel 14FL without the actuator 26) 14 in the normal roll control. fli 、F fri 、F rli and F rri These require control force F fli 、F fri 、F rli and F rri In order to achieve the required roll moment M r The control force required for each wheel 14.

[0039] Required rolling moment M r The roll moment required to suppress the roll behavior by roll control is expressed by the following formula (1). In formula (1), α is the roll control gain, β1 is the feedback control gain (FB control gain) with respect to the sprung roll velocity, is the roll angle, and s is the Laplace operator. The second term on the right side of equation (1) represents the feedback term of the sprung roll velocity of the vehicle 10. By having this feedback term, the sprung roll velocity can be made close to the desired target value to calculate the lateral acceleration a. y The corresponding required rolling moment M r In addition, the required rolling moment M r The calculation formula of may also have only the first term on the right side of formula (1). That is, the required rolling moment M r It can be simply the lateral acceleration a y The product of the roll control gain α.

[0040] [Formula 1]

[0041]

[0042] The controller 30 calculates the required roll moment M according to equation (1): r , the required roll moment M is calculated by the following formula (2): r Transformed (distributed) into the required control force F for the four wheels 14 fli 、F fri 、F rli and F rri In formula (2), T f is the front wheel track, T ris the rear wheel track. Assume that the required control force F fli 、F fri 、F rli and F rri It is positive when an upward force is required. Assume that the required rolling moment M r It is positive when the moment is required to move downward to the right and upward to the left.

[0043] [Formula 2]

[0044]

[0045] <Step S108>

[0046] At the lateral acceleration a y is the threshold value a yt In the above case (step S102 ; Yes), or when there is an abnormality in the vehicle stability control (step S104 ; Yes), the process proceeds to step S108 .

[0047] In step S108, the controller 30 calculates the required roll moment M according to the following equation (3): r The formula (3) is different from the formula (1) in the FB control gain β with respect to the sprung roll velocity. Specifically, in the formula (3), a value larger than the FB control gain β1 of the formula (1) is set as the FB control gain β2.

[0048] [Formula 3]

[0049]

[0050] In step S108, the controller 30 sets the required roll moment M r Transformed (distributed) into the required control force F for the four wheels 14 fli 、F fri 、F rli and F rri Specifically, the controller 30 calculates the required control force F for the four wheels 14 using the following equation (4): fli 、F fri 、F rli and F rri According to equation (4), in comparison with equation (2), in order to require the roll moment M r The roll moment generated on the front axle 16F (second axle) increases by an increase in the amount M rf .exist Figure 1 In the example of the vehicle 10 shown, the suspension 20FL of the left front wheel 14FL is a non-active suspension. rf The required control force F is reflected to the right front wheel 14FR having the actuator 26FR.fri .

[0051] [Formula 4]

[0052]

[0053] The controller 30 determines the increase amount M so as to suppress the deviation of the roll stiffness distribution. rf Specifically, the controller 30 determines the increase amount M by, for example, the following method: rf That is, at the lateral acceleration a y is the threshold value a yt In the above case, the controller 30 calculates the increase amount M according to the following formula (5): rf In equation (5), γ is the specified gain. By using equation (5), as the lateral acceleration a y becomes higher in the high acceleration region R2 (ie, as the lateral acceleration a y As the lateral acceleration a increases, the roll moment generated on the front axle 16F side gradually increases. y As the lateral acceleration a increases, the roll stiffness distribution gradually becomes biased towards the front axle 16F. y When the lateral acceleration a is less than the threshold ayt and the vehicle stability control is abnormal and the process proceeds to step S108, the controller 30 may calculate the lateral acceleration a y The product of itself and the specified gain is taken as the increase M rf .

[0054] [Formula 5]

[0055] M rf =γ(a y -a yt )…(5)

[0056] Furthermore, the control process involved in this embodiment may include a “distribution process”. In an example with this distribution process, the controller 30 calculates the required control force F for the four wheels 14 in such a way that the roll moment equal to the roll moment increased on the front axle 16F side is reduced on the rear axle 16R side. fli 、F fri 、F rli and F rri .

[0057] More specifically, M rrl and M rrr The amount of reduction in the roll moment generated on the two wheels 14RL and 14RR on the rear axle 16R (first axle) side. rf With 2 reductions M rrl and M rrrThere is a relationship expressed by the following formula (6). That is, by reducing the amount M rrl With the reduction M rrr The sum and increase M rf The reduction M is determined in the same way rrl and M rrr Therefore, according to the above-mentioned formula (4), the roll moment on the rear axle 16R side is reduced by a magnitude equal to the roll moment increased on the front axle 16F side.

[0058] [Formula 6]

[0059] M rf =M rrl +M rrr …(6)

[0060] Among them, regarding the allocation process, broadly speaking, the reduction amount M rrl and M rrr Each relative to the increase M rf The ratio can be set arbitrarily. However, the ratio can be determined as described later in "3. Specific example of allocation processing".

[0061] <Step S110>

[0062] After step S106 or S108, in step S110, the controller 30 calculates the required control force F in step S106 or S108. fli 、F fri 、F rli and F rri The actuators 26FR, 26RL, and 26RR for controlling the three wheels 14 are used.

[0063] Specifically, in step S110, the controller 30 requires the control force F fli 、F fri 、F rli and F rri Converted into the required control force F for the three wheels 14 with the actuator 26 fr 、F rl and F rr For this conversion, for example, the method described in Japanese Patent Application Laid-Open No. 2023-047810 can be used. The outline of the conversion according to this method is as follows.

[0064] Regarding the above transformation, the controller 30 first converts the required control force F into fli 、F fri 、F rli and F rriThe required value of the gravity center 3 mode is converted into the required value of the gravity center 3 mode. The gravity center 3 mode refers to the motion mode composed of the heave force, roll moment and pitch moment acting on the gravity center 11 of the vehicle 10. The required value of the gravity center 3 mode refers to the required heave force F shown in equation (7) ht , Required roll moment M rt And the required pitch moment M pt In equation (7), lf and lr are the distances between the centers of gravity of the front axle 16F and the rear axle 16R, respectively. rt The required roll moment M of the roll control according to the present embodiment is included r In addition, the required value of the center of gravity 3 mode may include a required value for any behavior control other than the above-mentioned roll control.

[0065] [Formula 7]

[0066]

[0067] Regarding the above conversion, the controller 30 then converts the required value of the center of gravity mode 3 into the required control force F for the three wheels 14 using the following equation (8): fr 、F rl and F rr , that is, the required control force of the three actuators 26.

[0068] [Formula 8]

[0069]

[0070] In step S110, the controller 30 sets the control force applied to the right front wheel 14FR in the vertical direction to the required control force F fr Similarly, the controller 30 controls the actuator 26FR in such a manner that the control force in the up-down direction applied to the right rear wheel 14RR becomes the required control force F rr The actuator 26RR is controlled in such a manner that the control force applied to the left rear wheel 14RL in the vertical direction becomes the required control force F rl In this way, the actuator 26RL is controlled based on the required control force F converted from the required value of the center of gravity 3 mode. fr 、F rl and F rr By controlling the actuators 26FR, 26RR, and 26RL, all desired behaviors including roll, pitch, and heave can be realized in the vehicle 10 .

[0071] In addition, the control of the actuator 26 described above is applied to the actuator 26 capable of realizing force (torque) control. Different from this control example, in the example of having the actuator 26 for position (angle) control of the three wheels 14, the controller 30 can control the three actuators 26 as follows. That is, the controller 30 calculates the required control forces F that satisfy the transformation of the formula (8): fr 、F rl and F rr The controller 30 performs position control of the three actuators 26 based on the calculated position control amounts.

[0072] <Effect>

[0073] As described above, according to the control process according to this embodiment, in the lateral acceleration a y When the acceleration exceeds the low acceleration region R1 and increases to the high acceleration region R2, the roll rigidity of the front axle 16F (second axle) is increased. Therefore, in the high acceleration region R2, regardless of the method of reducing the roll control gain (i.e., suppressing the lateral acceleration a y The deviation of the roll stiffness distribution can be suppressed even if the lateral acceleration a y In the low acceleration region R1, when there is an abnormality in the vehicle stability control, the roll rigidity of the front axle 16F (second axle) is also increased. Thus, even in the low acceleration region R1, when there is an abnormality in the vehicle stability control, the deviation of the roll rigidity distribution caused by the execution of the control process can be suppressed to suppress undesired oversteering or understeering, thereby improving the stability of the vehicle 10.

[0074] In addition, according to the allocation process included in the control process, the roll rigidity of the front axle 16F is increased based on the relationship between equations (4) and (6) (see step S108). r Instead, a part of the control force generated by the pair of left and right actuators 26RL and 26RR (first actuator) on the rear axle 16R side is distributed to the actuator 26FR (second actuator) on the front axle 16F side. Broadly speaking, the control process can be performed without the distribution process in a manner that simply increases the roll moment generated on the front axle 16F side. In contrast, by performing the distribution process, when the roll moment generated on the front axle 16F side is increased by the same amount, the deviation in the roll stiffness distribution can be effectively suppressed compared to the example without the distribution process.

[0075] In addition, according to the present embodiment, when the roll stiffness of the front axle 16F is increased by the control process, the FB control gain β for the sprung roll speed is increased (β2>β1). Thus, when the roll control is performed using the actuators 26 of the three wheels 14 in accordance with the control process, the variation of the sprung roll speed can be more quickly converged to suppress the deviation of the roll stiffness.

[0076] In addition, according to the control process of this embodiment, the roll rigidity of the front axle 16F in the high acceleration region R2 is increased based on the relationship of equation (5) (see step S108). y The higher the value, the more M rf The larger the value is, the greater the roll rigidity of the front axle 16F is. y The increase in roll rigidity can appropriately suppress the deviation of roll rigidity.

[0077] 3. Specific example of allocation processing

[0078] First, a specific example EX1 of the allocation process (refer to step S108) is described. In this specific example EX1, the controller 30 allocates a part of the control force to be generated by the actuator 26RR (first actuator) of the right rear wheel 14RR of the rear axle 16R located on the same side as the single wheel (right front wheel 14FR) of the front axle 16F having the actuator 26FR (second actuator) to the actuator 26FR.

[0079] More specifically, as expressed by equation (9), the reduction amount M of the right rear wheel 14RR is set to rrr With the increase M rf Therefore, according to the relationship of the above formula (5), the reduction amount M of the left rear wheel 14RL is rrl As expressed by equation (10), it becomes 0. Therefore, a portion of the control force to be generated by the actuator 26RR of the right rear wheel 14RR (that is, the reduction amount M rrr The corresponding control force) is taken as the increase M rf The corresponding control force is distributed to the actuator 26FR.

[0080] [Formula 9]

[0081] M rrr =M rf …(9)

[0082] M rrl =0…(10)

[0083] From the viewpoint of preventing the vehicle 10 from rolling over, a low height of the sprung center of gravity is preferred. According to specific example EX1, it is possible to prevent the generation of a force in the heave direction, and to distribute a portion of the control force that should be generated by the first actuator (e.g., actuator 26RR) on the rear axle 16R side to the second actuator (e.g., actuator 26FR). In more detail, according to the distribution involved in specific example EX1, a pitching action is generated in accordance with the output of the roll moment, but no force is generated in the heave direction. Therefore, it is possible to suppress the action of increasing the height of the sprung center of gravity, which is an action that may lead to a rollover. In this way, according to specific example EX1 (the same applies to specific examples EX2 and EX3 described later), it is possible to suppress unwanted oversteer or understeer in the high acceleration region R2 and prevent a rollover. In addition, instead of specific example EX1, the "reduction amount M" may be satisfied. rrr >M rrl "This relationship is used to determine the reduction amount M according to formula (5) rrl and M rrr According to this relationship, the effect of suppressing fluctuations can also be obtained.

[0084] Next, in the specific example EX2, according to the increase amount M rf The positive and negative values ​​of the reduction amount M are set as follows rrl and M rrr That is, the control force F of the first actuator that generates the roll moment on the rear axle 16R side is rl and F rr The downward control force F rl or F rr This is equivalent to lowering the height of the sprung center of gravity and is equivalent to resisting the lateral acceleration a y The force acting in the direction of the rollover of the vehicle 10 is caused by the action of .

[0085] In view of this, in the specific example EX2, the increase amount M rf When it is negative, the controller 30 sets the reduction amount M according to the relationship between the above equations (9) and (10). rrl and M rrr On the other hand, when increasing the amount M rf When is positive, the controller 30 sets the reduction amount M according to the relationship between the following equations (11) and (12), that is, the opposite relationship of the relationship between equations (9) and (10). rrl and M rrr . Thus, it is possible to achieve a more effective distribution process for reducing the height of the center of gravity on the sprung spring. In addition, the specific example EX2 can be replaced by satisfying the "reduction amount M rrl >M rrr "This relationship is used to determine the reduction amount M according to formula (5) rrl and M rrrBased on this relationship, it is also possible to achieve the effect of lowering the height of the sprung center of gravity.

[0086] [Formula 10]

[0087] M rrl =M rf …(11)

[0088] M rrr =0…(12)

[0089] In addition, the present invention is not limited to the specific example EX2, and the following specific example EX3 may be used to perform the operation while taking into account the increase amount M. rf The positive and negative distribution processing. Figure 4 This is a diagram for explaining a specific example EX3 of the allocation process. rf In the distribution process of positive and negative, the increase amount M rf When it is positive, the increase M rf Compared with the case where the absolute value is negative, the increase M rf The corresponding reduction M rrl Specifically, for example, Figure 4 The reduction amount M is set by the relationship shown in rrl and M rrr . Figure 4 τ in the equation is the reduction M rrr (absolute value) relative to the increase M rf Therefore, when the ratio τ is 1, the reduction amount M rrr With the increase M rf Equal. Figure 4 In the example shown, the increase in M rf When it is negative, the ratio τ is constant at 1, that is, the reduction amount M rrl On the other hand, when the amount of increase M rf When the ratio τ is positive, the increase M rf As the amount of M increases, it decreases linearly from 1 to 0. rrl From 0 straight line increases to the increase amount M rf The same size. By using such a specific example EX3, the effect of lowering the height of the center of gravity on the sprung spring can also be obtained.

[0090] 4. Other Implementation Methods

[0091] exist Figure 3 In the flowchart shown, even if the vehicle stability control is normal, if the lateral acceleration a yIn the high acceleration region R2, the control process using equation (4) is also executed. Alternatively, if the vehicle stability control is normal, regardless of the lateral acceleration a y Regardless of the level of , the normal processing using equation (2) is performed, and the control processing is performed only when the vehicle stability control is abnormal.

[0092] In addition, regarding the required rolling moment M r The calculation of the lateral acceleration a can be used instead of the feedback term of the sprung roll velocity (see equation (1) or (3)) y Moreover, similarly to the example of the sprung roll velocity, when the roll stiffness of the front axle 16F is increased by the control process, the feedback control gain for the above-mentioned time differential may be increased.

[0093] In addition, Figure 1 In the example shown, the suspension 20FL for the left front wheel 14FL is a non-active suspension without the actuator 26. Instead of this example, the suspension 20FR for the right front wheel 14FR may be a non-active suspension. Figure 1 The example shown is different in that the front axle 16F is the “first axle” and the rear axle 16R is the “second axle.” In this example, the suspension 20RL or 20RR on the rear axle 16R side is a non-active suspension.

[0094] Description of Reference Numerals

[0095] 10…vehicle; 12…body; 14…wheel; 16F…front axle; 16R…rear axle; 20…suspension; 26…actuator; 30…controller.

Claims

1. A vehicle behavior control device, characterized in that: have: A roll rigidity variable device configured to make variable the roll rigidity of a first shaft, which is one of the front shaft and the rear shaft of the vehicle, and a second shaft, which is the other of the front shaft and the rear shaft; and Controller, In at least a low acceleration region of a region of lateral acceleration acting on the vehicle, the controller controls the variable roll stiffness device so as to increase the roll stiffness of the first shaft in accordance with an increase in the lateral acceleration. When the lateral acceleration exceeds the low acceleration region and increases to the high acceleration region, or when there is an abnormality in the vehicle stability control that suppresses at least one of oversteering and understeering of the vehicle, the controller performs control processing to control the roll stiffness variable device in a manner that increases the roll stiffness of the second axis.

2. The vehicle behavior control device according to claim 1, characterized in that: The variable roll stiffness device comprises: a pair of left and right first actuators configured to apply a control force in a vertical direction to the left and right wheels of the first shaft; and The second actuator is configured to apply a control force in the up-down direction to the single wheel of the second shaft, The controller calculates a required roll moment corresponding to the lateral acceleration, The control process includes a distribution process of distributing a part of the control force to be generated by the pair of left and right first actuators in order to realize the required roll moment to the second actuator.

3. The vehicle behavior control device according to claim 2, characterized in that: In the distribution process, the controller distributes a portion of the control force to be generated by one of the left and right pairs of first actuators provided for one of the left and right wheels of the first shaft located on the same side as the single wheel of the second shaft to the second actuator.

4. The vehicle behavior control device according to claim 2 or 3, characterized in that: The required roll moment includes a feedback term of the sprung roll velocity of the vehicle, The feedback term includes a feedback control gain for the roll velocity, When the lateral acceleration exceeds the low acceleration region and increases to the high acceleration region, or when the abnormality exists, the controller selects the feedback control gain larger than when the lateral acceleration is in the low acceleration region and the abnormality does not exist.

5. The vehicle behavior control device according to any one of claims 1 to 3, characterized in that: In the control process, the controller controls the roll stiffness variable device so as to increase the roll stiffness of the second shaft as the lateral acceleration increases.

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