Vehicle behavior control system
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2023-08-25
- Publication Date
- 2026-05-15
Smart Images
Figure 0007859407000013 
Figure 0007859407000014 
Figure 0007859407000015
Abstract
Description
[Technical Field]
[0001] This disclosure relates to a vehicle behavior control device. [Background technology]
[0002] Patent Document 1 discloses a vehicle roll control device. This roll control device increases the control amount of actuators on both the first and second axles (rear axle and front axle) to increase the roll stiffness of the first and second axles in response to an increase in lateral acceleration. When the lateral acceleration increases beyond the low acceleration range to the high acceleration range, the roll control device reduces the gain of the control amount of the actuator on the first axle side with respect to lateral acceleration in response to the increase in lateral acceleration so that the roll stiffness distribution ratio of the first axle does not exceed a predetermined value. [Prior art documents] [Patent Documents]
[0003] [Patent Document 1] Japanese Patent Publication No. 2023-051026 [Overview of the project] [Problems that the invention aims to solve]
[0004] According to the technology described in Patent Document 1, it is possible to suppress the bias in roll stiffness distribution in the high-acceleration range and prevent the occurrence of unintended oversteer or understeer. However, the method of lowering the roll control gain makes it easier for large roll to occur in the high-acceleration range. Furthermore, even if the lateral acceleration is low, if there is an abnormality in vehicle stability control, the bias in roll stiffness distribution can become a factor that easily causes unintended oversteer or understeer, for example, depending on the road surface conditions.
[0005] This disclosure has been made in view of the above-mentioned problems, and aims to provide a vehicle behavior control device that can suppress bias in roll stiffness distribution while considering the suppression of large rolls in response to lateral acceleration or the state of vehicle stability control. [Means for solving the problem]
[0006] The vehicle behavior control device according to this disclosure comprises a roll stiffness variable device and a controller. The roll stiffness variable device is configured to vary the roll stiffness of a first axle, which is one of the front axle and rear axle of the vehicle, and the roll stiffness of a second axle, which is the other of the front axle and rear axle. The controller controls at least one of the ranges of lateral acceleration acting on the vehicle. Low acceleration range with margin for the vehicle's turning limit In this system, the roll stiffness variable device is controlled to increase the roll stiffness of the first axis in response to an increase in lateral acceleration. The high acceleration range is the acceleration range near the turning limit. If the roll stiffness increases to a certain level, or if there is a malfunction in the vehicle stability control that suppresses at least one of the vehicle's oversteer and understeer, the controller executes a control process to control the variable roll stiffness device to increase the roll stiffness of the second axis. [Effects of the Invention]
[0007] According to this disclosure, beside When acceleration increases beyond the low acceleration range to the high acceleration range, it becomes possible to suppress the bias in roll stiffness distribution without relying on a method to reduce the roll control gain (i.e., while suppressing the occurrence of large rolls corresponding to lateral acceleration). Furthermore, according to this disclosure, even in the low acceleration range, if there is an abnormality in vehicle stability control, unintended oversteer or understeer can be suppressed by suppressing the bias in roll stiffness distribution through the execution of control processing. [Brief explanation of the drawing]
[0008] [Figure 1] This diagram shows the configuration of a vehicle equipped with a behavior control device according to the embodiment. [Figure 2] This diagram conceptually shows the basic configuration of the roll control according to the embodiment. [Figure 3] This flowchart shows an example of a roll control process, including the control process according to the embodiment. [Figure 4]This is a diagram to explain the specific example EX3 of the allocation process. [Modes for carrying out the invention]
[0009] 1. Vehicle behavior control system Figure 1 shows the configuration of a vehicle 10 equipped with a behavior control device according to an embodiment. As shown in Figure 1, the vehicle 10 has four wheels 14, with the left front wheel 14FL and the right front wheel 14FR on the front axle 16F, and the left rear wheel 14RL and the right rear wheel 14RR on the rear axle 16R. In the vehicle 10, for example, the left and right wheels 14FL and 14FR are steering wheels.
[0010] Vehicle 10 is equipped with suspensions 20FL, 20FRA, 20RLA, and 20RRA. The suspensions 20FL, 20FRA, 20RLA, and 20RRA suspend the left front wheel 14FL, the right front wheel 14FR, the left rear wheel 14RL, and the right rear wheel 14RR from the vehicle body 12, respectively.
[0011] The left front wheel 14FL suspension 20FL is an inactive suspension and consists of a spring 22FL and a shock absorber 24FL.
[0012] The suspension 20FRA of the right front wheel 14FR is an active suspension (fully 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 vertical control force between the vehicle body 12 and the right front wheel 14FR. The actuator 26FR is, for example, electrically or hydraulically operated.
[0013] The rear axle 16R suspensions 20RLA and 20RRA are also active suspensions, comprising springs 22RL and 22RR and shock absorbers 24RL and 24RR, respectively, in addition to actuators 26RL and 26RR. Actuators 26RL and 26RR are configured to actively apply vertical control forces between the vehicle body 12 and the left and right wheels 14RL and 14RR of the rear axle 16R, respectively. Actuators 26RL and 26RR are, for example, electrically or hydraulically operated.
[0014] The vehicle 10 is equipped with a controller 30. The controller 30 acquires signals from a group of sensors 40 mounted on the vehicle 10. The group of sensors 40 includes, for example, sensors that measure physical quantities related to the behavior of the vehicle 10, such as an acceleration sensor, a vehicle height sensor, a sprung mass acceleration sensor, and a wheel speed sensor. The controller 30 also controls the actuators 26FR, 26RL, and 26RR.
[0015] The controller 30 includes a processor 32 and a memory 34 coupled to the processor 32. The processor 32 performs various processes related to controlling the behavior of the vehicle 10. The behavior control includes at least the roll control described later. The memory 34 stores various information necessary for the processor 32 to perform various processes. For example, the memory 34 stores a program 36 that can be executed by the processor 32 and various information related to the program 36. The execution of the program 36 by the processor 32 realizes the behavior control.
[0016] Furthermore, 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 that suppresses at least one of oversteer and understeer of the vehicle 10. Vehicle stability control includes, for example, the controller 30 using the sensor group 40 to detect a skid of the vehicle 10 and controlling at least one of the drive system and braking system of the vehicle 10 to suppress the skid. The drive system is, for example, at least one of an electric motor and an internal combustion engine.
[0017] 2. Roll Control of Vehicle In this 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 variably changes the roll stiffness of the rear axle 16R and the roll stiffness of the front axle 16F. And the "behavior control device" according to this embodiment includes the roll stiffness variable device and a controller 30. The roll control according to this embodiment is executed by the controller 30 that controls the roll stiffness variable device.
[0018] First, FIG. 2 is a diagram conceptually showing the basic configuration of the roll control according to the embodiment. In FIG. 2, a modeled vehicle 10, a lateral acceleration (lateral G) a y acting on the center of gravity 11 of the vehicle 10, and control forces F rl and F rr for roll suppression applied by the roll stiffness variable device are shown. On the left side of FIG. 2, a state where the lateral acceleration a y is low is shown, and on the right side, a state where the lateral acceleration a y has increased is shown. Also, FIG. 2 shows a graph indicating changes in the roll stiffness distribution ratio between the front axle 16F and the rear axle 16R before and after the lateral acceleration a y increases.
[0019] The basic configuration of the roll control in the vehicle 10 having the suspension configuration shown in FIGS. 1 and 2 is as follows. That is, on the side of the rear axle 16R equipped with the active suspensions 20RLA and 20RRA on both the left and right wheels 14RL and 14RR, reverse-phase F rl and F rr are generated by the actuators 26RL and 26RR. More specifically, as shown in FIG. 2, for example, when a lateral acceleration a y in the right direction acts on the vehicle 10, a downward control force F rl is applied to the left rear wheel 14RL by the actuator 26RL, and an upward control force F rrThis is provided. As a result, in the vehicle 10 having the above suspension configuration, the lateral acceleration a is achieved without generating heave and pitch. y It is possible to generate a roll moment that suppresses the roll caused by the lateral acceleration a. y This allows for an increase in the roll stiffness of the rear axle 16R (first axle).
[0020] Furthermore, according to the basic configuration of roll control, the control force F applied to the left and right wheels 14RL and 14RR is rl and F rr As will be explained in detail later, this refers to the lateral acceleration a y It increases in accordance with the lateral acceleration a. y The controller 30 controls the roll stiffness of the rear axle 16R to increase in response to the increase in lateral acceleration a. y The length of the arrow indicating the direction is equal to the lateral acceleration a y This indicates the magnitude of the control force F. rl and F rr The length of the arrows indicating the direction corresponds to the control force F. rl and F rr This indicates the size.
[0021] According to the basic configuration of roll control, as shown in Figure 2, the lateral acceleration a y As the roll stiffness of the rear axle 16R increases in response to the increase in lateral acceleration a, the roll stiffness distribution ratio of the rear axle 16R increases. y As the amount increases, the bias in the roll stiffness distribution ratio increases. This is because high lateral acceleration a y This can lead to unintended oversteer or understeer during cornering. In this regard, reducing the roll control gain in the high-acceleration range can suppress the occurrence of unintended oversteer or understeer. However, this method tends to cause large roll in the high-acceleration range. Furthermore, measures to suppress bias in roll stiffness distribution should preferably be taken while considering the state of vehicle stability control.
[0022] Therefore, the processing performed by the controller 30 with respect to roll control according to this embodiment includes "control processing". In the control processing, the controller 30 controls the lateral acceleration a y If the acceleration exceeds the low acceleration range R1 and increases to the high acceleration range R2, or if there is an abnormality in the "vehicle stability control," the variable roll stiffness device is controlled to increase the roll stiffness of the front axle 16F (second axle).
[0023] Figure 3 is a flowchart showing an example of a roll control process, including control processing according to the embodiment. The processing in this flowchart is repeatedly executed by the controller 30 (processor 32) while the vehicle 10 is in motion.
[0024] <Step S100> First, in step S100, the controller 30 uses the sensor group 40 to measure the lateral acceleration a y To obtain the lateral acceleration a. y This is an estimated value derived, for example, from the steering angle and vehicle speed. However, lateral acceleration a y The method of obtaining this is not particularly limited. Lateral acceleration a y This could be, for example, a sensor value measured by an accelerometer.
[0025] <Step S102> Next, in step S102, the controller 30 receives the lateral acceleration a obtained in step 100. y a predetermined threshold a yt Determine whether or not the value is greater than or equal to the value. That is, the lateral acceleration a y It is determined whether the device is in the high-acceleration region R2 or the low-acceleration region R1.
[0026] More specifically, the high acceleration region R2 corresponds to the acceleration region near the turning limit of the vehicle 10. Therefore, the lateral acceleration a y is threshold a ytBeing less than (i.e., being in the low acceleration region R1) means that there is a margin of safety relative to the turning limit. When this margin exists, unintended oversteer or understeer, or large roll, will not occur. For this reason, in step S102, the lateral acceleration a relative to the turning limit is y The margin of error is determined. For example, simply, the lateral acceleration a y is threshold a yt If the above is true (i.e., it is in the high acceleration region R2), it is determined that the margin for the turning limit is small. Also, if it is possible to calculate the estimated friction coefficient of the road surface on which the vehicle 10 is traveling, a threshold a is used to determine the margin for the limit lateral acceleration according to the estimated friction coefficient. yt This may be determined by taking into account the estimated coefficient of friction.
[0027] <Step S104> lateral acceleration a y is threshold a yt If the value is less than (step S102; No), the controller 30 determines in step S104 whether or not there is an abnormality in the vehicle stability control. The method for determining the abnormality is not particularly limited, and any known determination method may be used.
[0028] <Step S106> If the result of the determination in step S104 is No (i.e., lateral acceleration a y is threshold a yt If the value is less than and the vehicle stability control is normal, the process proceeds to step S106. Hereinafter, the time when the process proceeds to step S106 in this manner will simply be referred to as "normal operation".
[0029] In step S106, the controller 30 requests a control force F for each wheel (i.e., four wheels including the left front wheel 14FL without actuator 26) 14 during normal roll control. fli F fri F rli , and F rri The required control force F is calculated. fli F fri F rli , and Frri The required role moment M r This is the control force required for each wheel 14 to achieve this.
[0030] Required role moment M r α is the roll moment required to suppress roll behavior by roll control, and is expressed by the following equation (1). In equation (1), α is the roll control gain, β1 is the feedback control gain (FB control gain) with respect to the sprung mass roll velocity, φ is the roll angle, and s is the Laplace operator. The second term on the right-hand side of equation (1) represents the feedback term for the sprung mass roll velocity of the vehicle 10. By having this feedback term, the lateral acceleration a can be controlled while bringing the sprung mass roll velocity closer to the desired target value. y Required roll moment M r It can be calculated. Note that the required roll moment M r The calculation formula may, for example, consist only of the first term on the right-hand side of equation (1). That is, the required roll moment M r This is simply the lateral acceleration a y It may also be the product of this and the roll control gain α.
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[0031] The controller 30 calculates the required roll moment M according to equation (1). r The required roll moment M is calculated using the following formula (2). r The required control force F for the four wheels 14 fli F fri F rli , and F rri Convert (distribute) to. In equation (2), T f This is the front wheel tread, T r This is the rear wheel tread. Required control force F fli F fri F rli , and F rri This is considered positive when an upward force is required. Required roll moment M rThis is considered positive when a moment that is downward to the right and upward to the left is required.
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[0032] <Step S108> lateral acceleration a y is threshold a yt If any of the above conditions are met (Step S102; Yes), or if there is an abnormality in the vehicle stability control (Step S104; Yes), the process proceeds to Step S108.
[0033] In step S108, the controller 30 calculates the required roll moment M according to the following equation (3). r Equation (3) is used to calculate the FB control gain β with respect to the sprung roll speed. Specifically, in equation (3), a value greater than the FB control gain β1 in equation (1) is set as the FB control gain β2.
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[0034] In step S108, the controller 30 performs control processing to obtain the requested roll moment M r The required control force F for the four wheels 14 fli F fri F rli , and F rri It is converted (distributed) to the following. Specifically, the controller 30 calculates the required control force F for the four wheels 14 according to equation (4) below. fli F fri F rli , and F rri The required roll moment M is calculated. According to equation (4), in comparison with equation (2), r To achieve this, the roll moment generated by the front axle 16F (second axle) increases by M. rf It is increased by 1 minute. In the example of vehicle 10 shown in Figure 1, the suspension 20FL of the left front wheel 14FL is an inactive suspension. Therefore, the increase amount M rfis reflected in the required control force F of the right front wheel 14FR having the actuator 26FR. fri is reflected therein.
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[0035] The controller 30 determines an increase amount M so that the bias of the roll rigidity distribution is suppressed. rf Specifically, the controller 30 determines the increase amount M by, for example, the following method. rf That is, the controller 30 determines the increase amount M when the lateral acceleration a y is greater than or equal to the threshold value a yt according to the following formula (5). In formula (5), γ is a predetermined gain. By using formula (5), in the high acceleration range R2, as the lateral acceleration a rf increases (that is, as the lateral acceleration a y approaches the turning limit), the roll moment generated on the front axle 16F side increases. In other words, as the lateral acceleration a y increases, the roll rigidity distribution becomes closer to the front axle 16F. Also, when the lateral acceleration a y is less than the threshold value a y and the process proceeds to step S108 due to an abnormality in the vehicle stability control, the controller 30 may calculate, for example, the product of the lateral acceleration a yt itself and a predetermined gain as the increase amount M y . rf
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[0036] Furthermore, the control process according to this embodiment may include "distribution processing". In an example with this distribution processing, the controller 30 reduces the roll moment of the same magnitude as the increased roll moment on the front axle 16F side on the rear axle 16R side, and the required control forces F fli for the four wheels 14, F fri 、F rli 、and F rri are calculated.
[0037] More specifically, M rrl and M rrr These represent the decrease in roll moment generated by the two wheels 14RL and 14RR on the rear axle 16R (first axle) side, respectively. Increase amount M rf and two decrease amounts M rrl and M rrr The relationship between them is expressed by the following equation (6): That is, the decrease amount M rrl and M rrr is the amount of decrease M rrl and the amount of decrease M rrr The sum of these is the increase M rf It is determined to be equal to the above. Therefore, according to equation (4) above, the roll moment reduced on the rear axle 16R side will be equal in magnitude to the roll moment increased on the front axle 16F side.
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[0038] Furthermore, regarding the allocation process, broadly speaking, the increase amount M rf Decrease M rrl and M rrr Each of these proportions may be set arbitrarily. However, these proportions may be determined as described later in "3. Specific Examples of Allocation Processing".
[0039] <Step S110> After step S106 or S108, in step S110, the controller 30 receives the required control force F calculated in step S106 or S108. fli F fri F rli , and F rri Based on this, the actuators 26FR, 26RL, and 26RR of the three wheels 14 are controlled.
[0040] Specifically, in step S110, the controller 30 requests the control force F fli F fri F rli , and Frri The required control force F for the three wheels 14 having actuators 26 fr、 F rl , and F rr Convert to [the specified format]. For this conversion, for example, the method described in Japanese Patent Publication No. 2023-047810 can be used. The outline of the conversion according to this method is as follows:
[0041] Regarding the above conversion, the controller 30 first calculates the required control force F using the following equation (7). fli F fri F rli , and F rri This is converted to the required values for the three modes of gravity. The three modes of gravity refer to the motion modes consisting of the heave force, roll moment, and pitch moment acting on the center of gravity 11 of the vehicle 10. The required values for the three modes of gravity are the required heave force F shown in equation (7). ht , required role moment M rt , and required pitch moment M pt This refers to the following: In equation (7), lf and lr are the distance between the centers of gravity of the front axle 16F and the rear axle 16R, respectively. In addition, the required roll moment M rt This is the required roll moment M for roll control according to this embodiment. r It includes the following. Furthermore, the required values for the three center of gravity modes may include required values for any behavioral control other than the roll control described above.
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[0042] Regarding the above conversion, the controller 30 then calculates the required values for the center of gravity 3 modes and the required control force F for the 3 wheels 14 according to the following equation (8). fr、 F rl , and F rr In other words, it is converted into the required control force for the three actuators 26.
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[0043] In step S110, the controller 30 determines that the vertical control force applied to the right front wheel 14FR is the required control force F. fr The actuator 26FR is controlled to achieve the desired control force F. Similarly, the controller 30 controls the vertical control force applied to the right rear wheel 14RR to obtain the required control force F. rr The actuator 26RR is controlled to achieve the required control force F, which is the vertical control force applied to the left rear wheel 14RL. rl The actuator 26RL is controlled to achieve this. The required control force F is converted from the required values of the three modes of the center of gravity in this manner. fr、 F rl , and F rr By controlling each actuator 26FR, 26RR, and 26RL based on this, the desired behavior, including roll, pitch, and heave, is achieved in the vehicle 10.
[0044] In addition, the control of the actuator 26 described above applies to actuators 26 capable of force (torque) control. Unlike this control example, in an example where actuators 26 perform position (angle) control on three wheels 14, the controller 30 may control the three actuators 26 as follows: That is, the controller 30 controls each required control force F converted by equation (8). fr、 F rl , and F rr The controller 30 calculates the position control amounts for the three actuators 26 that satisfy the condition. Then, the controller 30 controls the positions of the three actuators 26 according to the calculated position control amounts.
[0045] <Effects> As explained above, according to the control process of this embodiment, the lateral acceleration a y When the lateral acceleration a increases beyond the low acceleration range R1 to the high acceleration range R2, the roll stiffness of the front axis 16F (second axis) increases. This allows the lateral acceleration a to be controlled without relying on methods to reduce the roll control gain in the high acceleration range R2 (i.e., when the lateral acceleration a y (While suppressing the occurrence of large rolls in response to this,) it becomes possible to suppress the bias in the roll stiffness distribution. Furthermore, according to this embodiment, the lateral acceleration ay If there is an abnormality in the vehicle stability control even when the vehicle is in the low acceleration range R1, the roll stiffness of the front axle 16F (second axle) is increased. As a result, even in the low acceleration range R1, if there is an abnormality in the vehicle stability control, unintended oversteer or understeer can be suppressed by suppressing the bias in the distribution of roll stiffness due to the execution of control processing, thereby improving the stability of the vehicle 10.
[0046] Furthermore, according to the distribution process included in the control process, the increase in the roll stiffness of the front shaft 16F is performed based on the relationship between equations (4) and (6) (see step S108). That is, the required roll moment M r To achieve this, a portion of the control force that should be generated by the left and right pair of actuators 26RL and 26RR (first actuators) 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 may be performed simply to increase the roll moment generated on the front axle 16F side without distribution processing. In contrast, by including distribution processing, it becomes possible to effectively suppress the bias in roll stiffness distribution when increasing the roll moment generated on the front axle 16F side by the same amount, compared to the example without distribution processing.
[0047] Furthermore, according to this embodiment, when the roll stiffness of the front axle 16F is increased by the control process, the FB control gain β with respect to the sprung roll speed is increased (β2 > β1). As a result, when roll control is performed using the actuators 26 of the three wheels 14 with control processing, it becomes possible to suppress the bias in roll stiffness while more quickly settling the change in sprung roll speed.
[0048] Furthermore, according to the control processing of this embodiment, the increase in the roll stiffness of the front shaft 16F in the high acceleration region R2 is performed based on the relationship in equation (5) (see step S108). That is, lateral acceleration a y The higher the value, the greater the increase M. rf This increases the roll stiffness of the front axle 16F. As a result, the lateral acceleration a in the high acceleration region R2 yAs the value increases, the bias in roll stiffness can be appropriately suppressed.
[0049] 3. Specific examples of allocation processing First, a specific example EX1 of the distribution process (see step S108) will be explained. In this specific example EX1, the controller 30 distributes a portion of the control force that should be generated by the actuator 26RR (first actuator) of the right rear wheel 14RR of the rear axle 16R, which is located on the same side as one wheel (right front wheel 14FR) of the front axle 16F having actuator 26FR (second actuator), to actuator 26FR.
[0050] More specifically, as shown by equation (9), the reduction amount M of the right rear wheel 14RR is rrr Increase amount M rf It is set to be equal to . Therefore, from the relationship in equation (5) above, the reduction amount M of the left rear wheel 14RL is rrl This becomes 0, as shown by equation (10). As a result, a portion of the control force that should be generated by the actuator 26RR of the right rear wheel 14RR (i.e., reduction amount M) is lost. rrr The control force (corresponding to the increase) is M rf The control force corresponding to this is distributed to the actuator 26FR.
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[0051] From the perspective of preventing the vehicle 10 from overturning, a lower sprung mass center of gravity is preferable. According to specific example EX1, while preventing the generation of heave force, a portion of the control force that should be generated by the first actuator on the rear axle 16R side (e.g., actuator 26RR) can be distributed to the second actuator (e.g., actuator 26FR). More specifically, according to the distribution in specific example EX1, pitch behavior occurs according to the output of the roll moment, but no force is generated in the heave direction. Therefore, the behavior in which the sprung mass center of gravity rises, which can lead to overturning, can be suppressed. In this way, according to specific example EX1 (and similarly for specific examples EX2 and EX3 described later), overturning can be prevented in the high acceleration range R2 while suppressing unintended oversteer or understeer. In addition, reduction amount M rrl and M rrr Instead of using specific example EX1, we will use "Decrease M". rrr >M rrl The relationship can also be determined from equation (5) while satisfying the following condition. This relationship also has the effect of suppressing heave.
[0052] Next, in specific example EX2, the decrease amount M rrl and M rrr The increase is M rf Depending on whether it is positive or negative, it is set as follows: namely, the control force F of the first actuator that generates a roll moment on the rear axle 16R side. rl and F rr Of these, the downward control force F rl or F rr This corresponds to the direction of lowering the height of the sprung mass center of gravity, and also to the lateral acceleration a y This corresponds to a force acting in a direction that prevents the vehicle 10 from overturning due to the action of [the vehicle].
[0053] Therefore, in specific example EX2, the increase amount M rf If the value is negative, the controller 30 will decrease the value M according to the relationship between equations (9) and (10) above. rrl and M rrr Set the amount M. rfIf the value is positive, the controller 30 decreases the amount M according to the relationship between equations (11) and (12) below, that is, the inverse relationship between equations (9) and (10). rrl and M rrr This is set. This enables a distribution process that can further effectively lower the sprung mass center of gravity. In addition, the reduction amount M rrl and M rrr Instead of using specific example EX2, we will use "Decrease M". rrl >M rrr It may also be determined from equation (5) while satisfying the relationship ''. This relationship also provides the effect of lowering the height of the sprung mass center of gravity.
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[0054] Also, increase amount M rf Allocation processing that takes into account the sign of the value may be performed not only in example EX2, but also in example EX3. Figure 4 is a diagram illustrating example EX3 of the allocation processing. That is, increase amount M rf In allocation processing where the sign of is taken into consideration, the increase M rf If the value is positive, the increase is M. rf Compared to the case where it is negative, the increase M is the same in absolute value. rf The corresponding decrease amount M rrl It is sufficient if the value is set to a large value. Specifically, for example, according to the relationship shown in Figure 4, the decrease amount M rrl and M rrr This may be set. In Figure 4, τ is the increase M. rf The decrease M relative to the absolute value of ( rrr This is the ratio of (the absolute value of). Therefore, when the ratio τ is 1, the decrease amount M rrr The increase is M rf This is equal to the increase M shown in Figure 4. rf If it is negative, the ratio τ is constant at 1, that is, the decrease M rrl It is constant at 0. On the other hand, the increase M rf If it is positive, the rate τ is the increase M rfAs the value increases, it decreases linearly from 1 to 0. Consequently, the amount of decrease M rrl The increase is M from 0. rf It increases linearly by the same magnitude. This specific example, EX3, also provides the effect of lowering the height of the sprung mass center of gravity.
[0055] 4. Other Embodiments In the flowchart shown in Figure 3, even if vehicle stability control is normal, the lateral acceleration a y If the lateral acceleration a is in the high acceleration region R2, control processing using equation (4) is executed. Alternatively, if the vehicle stability control is normal, the lateral acceleration a y The normal process using equation (2) is executed regardless of the level of the condition, and the control process may be executed only when the vehicle stability control is abnormal.
[0056] Also, the required roll moment M r In calculating the lateral acceleration a, instead of the feedback term for the sprung roll velocity (see equation (1) or (3)), y A feedback term of the time derivative may be used. And, similar to the example of the sprung roll speed, the feedback control gain for the time derivative may be increased when the roll stiffness of the front axle 16F is increased by the control process.
[0057] Furthermore, in the example shown in Figure 1, the suspension 20FL for the left front wheel 14FL is an inactive suspension without an actuator 26. Alternatively, the suspension 20FR for the right front wheel 14FR may be an inactive suspension. Also, unlike the example shown in Figure 1, the front axle 16F may be the "first axle" and the rear axle 16R may be the "second axle". In this example, the suspension 20RL or 20RR on the rear axle 16R side will be an inactive suspension. [Explanation of Symbols]
[0058] 10 vehicles, 12 car bodies, 14 wheels, 16 front axles, 16 rear axles, 20 suspensions, 26 actuators, 30 controllers
Claims
1. A variable roll stiffness device configured to vary the roll stiffness of a first axle, which is one of the front axle and rear axle of a vehicle, and the roll stiffness of a second axle, which is the other of the front axle and rear axle. Controller and Equipped with, The aforementioned controller, In the low acceleration range of the lateral acceleration range acting on the vehicle, where there is a margin of safety relative to the turning limit of the vehicle, the roll stiffness variable device is controlled to increase the roll stiffness of the first axis in response to the increase in the lateral acceleration. If the lateral acceleration increases beyond the low acceleration range to the high acceleration range which is the acceleration range near the turning limit, or if there is an abnormality in the vehicle stability control that suppresses at least one of the oversteer and understeer of the vehicle, a control process is executed to control the variable roll stiffness device to increase the roll stiffness of the second axis. A vehicle behavior control device characterized by the following:
2. The aforementioned variable roll stiffness device is A pair of left and right first actuators configured to apply vertical control force to the left and right wheels of the first axle, A second actuator configured to apply vertical control force to one wheel of the second axle, Includes, The controller calculates the required roll moment according to the lateral acceleration, The control process includes a distribution process that distributes a portion of the control force to be generated by the pair of left and right first actuators in order to achieve the required roll moment to the second actuator. The vehicle behavior control device according to feature 1.
3. In the distribution process, the controller distributes to the second actuator a portion of the control force to be generated by one of the left and right first actuators, which are provided for one of the left and right wheels of the first axle located on the same side as the wheel of the second axle. The vehicle behavior control device according to feature 2.
4. The requested roll moment includes a feedback term of the roll speed on the vehicle's sprung mass, The aforementioned feedback term includes a feedback control gain with respect to the roll speed, If the lateral acceleration increases beyond the low acceleration range to the high acceleration range, or if there is an abnormality, the controller selects a larger feedback control gain than when the lateral acceleration is in the low acceleration range and there is no abnormality. The vehicle behavior control device according to claim 2 or 3.
5. In the control process described above, the controller controls the variable roll stiffness device such that the roll stiffness of the second axis increases as the lateral acceleration increases. A vehicle behavior control device according to any one of claims 1 to 3.