Vehicle behavior control device, vehicle behavior control method and vehicle behavior control program

Abstract

To provide technique which makes it possible to reduce a cost in regard with a vehicle behavior control device.SOLUTION: A vehicle behavior control device comprises an i-th suspension which is provided on an i-th wheel (i=1, 2, 3) among four wheels of a vehicle, a fourth suspension which is provided on a fourth wheel except for the i-th wheel and a controller. The i-th suspension contains an i-th actuator which is positionally controlled by the controller. The controller is configured so as to acquire request value of behavior parameter which determines behavior of the vehicle and to convert the request value of the behavior parameter to an i-th request control force for the i-th wheel and to calculate an i-th position control amount of the i-th actuator on the basis of the i-th request control force and to perform position control of the i-th actuator according to the i-th position control amount.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a technique for controlling the behavior of a vehicle. [Background technology]

[0002] Patent Document 1 discloses a technique for controlling the behavior of a vehicle with a small number of actuators. In particular, the technique discloses a technique that enables the same control as when an actuator is provided for each of the four wheels, by using actuators provided for three of the four wheels. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-047810 A Summary of the Invention [Problem to be solved by the invention]

[0004] The technology disclosed in Patent Document 1 controls the force (torque) of each actuator. In order to control the force (torque) of an actuator, it is necessary to mount at least a force sensor or a torque sensor for detecting the force (torque). For this reason, actuators configured to enable force (torque) control are expensive.

[0005] In view of the above-mentioned problems, one object of the present disclosure is to provide a technique that enables cost reduction regarding vehicle behavior control. [Means for solving the problem]

[0006] A first aspect of the present disclosure relates to a vehicle behavior control device.

[0007] A vehicle behavior control device according to a first aspect includes an ith suspension provided on an ith wheel (i=1, 2, 3) among four wheels of a vehicle, a fourth suspension provided on a fourth wheel other than the ith wheel, and a controller. The ith suspension includes an ith actuator whose position is controlled by the controller. The controller is configured to obtain a required value of a behavior parameter that determines the behavior of the vehicle, convert the required value of the behavior parameter into an ith required control force for the ith wheel, calculate an ith position control amount of the ith actuator based on the ith required control force, and perform position control of the ith actuator in accordance with the ith position control amount. Effect of the Invention

[0008] According to the present disclosure, it is possible to reduce the cost of a vehicle behavior control device. [Brief description of the drawings]

[0009] [Figure 1] 2 is a diagram showing a behavior model for vehicle behavior control by the vehicle behavior control device according to the embodiment; FIG. [Diagram 2] 1 is a diagram for explaining a configuration of a vehicle behavior control device according to an embodiment; [Diagram 3] FIG. 2 is a diagram illustrating an example of a configuration of an actuator according to the embodiment. [Figure 4] FIG. 2 illustrates an active suspension according to an embodiment modeled in terms of spring elements. [Diagram 5] 3 is a flowchart showing a process executed in the behavior control device according to the first embodiment. [Figure 6] 10 is a flowchart showing a process executed for correcting a required value of a behavior parameter. [Figure 7] 10 is a flowchart showing a process executed in a behavior control device according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 1. First embodiment 1.1 Vehicle behavior model Vehicle behavior control by the vehicle behavior control device according to the first embodiment is performed based on a behavior model. FIG. 1 shows a behavior model for the behavior control of a vehicle 10 by the vehicle behavior control device according to the first embodiment. In the behavior control of the vehicle 10, required values ​​of behavior parameters that determine the behavior of the vehicle 10 are calculated, and control is performed to realize the calculated required values. In the first embodiment, a vertical control force for each wheel is adopted as the behavior parameter. In the behavior model shown in FIG. 1, a vertical control force F rli and the vertical control force F rri and the vertical control force F fli and the vertical control force F fri and are illustrated.

[0011] Various types of control are assumed for the behavior control of the vehicle 10 according to the purpose. For example, the behavior control of the vehicle 10 includes sprung feedback control, unsprung feedback control, preview control, attitude control, and the like. The sprung feedback control suppresses the vibration of the sprung part based on the sprung state quantity calculated using the measurement values ​​of the sprung acceleration sensor. The unsprung feedback control suppresses the vibration of the unsprung part based on the unsprung state quantity calculated using the measurement values ​​of the sprung acceleration sensor and the vehicle height sensor. The preview control predicts the road surface condition using a database of camera images and high-precision map data, and suppresses the vibration. The attitude control controls the attitude in response to steering and acceleration. Of course, these various types of control may be combined.

[0012] The required value of the behavior parameter is calculated so as to achieve the purpose of the behavior control. In this embodiment, the behavior control may be any of the various types of control as described above. That is, in this embodiment, the method of calculating the required value of the behavior parameter is not particularly limited.

[0013] The behavior of the vehicle 10 is affected by the roll moment M acting on the center of gravity of the vehicle 10. r , pitch moment Mp , and the heave force F h Therefore, the required values ​​of the behavior parameters can be converted to the center of gravity 3 mode. In particular, when the vertical control force for each wheel is used as the behavior parameter, it can be converted to the center of gravity 3 mode by the following formula (1). In formula (1), l f , l r , T f , and T r are the distance between the centers of gravity of the front axles, the distance between the centers of gravity of the rear axles, the front tread, and the rear tread, respectively (see FIG. 1). These parameters can be managed in advance as specification information of the vehicle 10.

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[0014] In the following, the values ​​obtained by converting the required values ​​of the behavior parameters into the center of gravity 3 mode are called "required values ​​of the center of gravity 3 mode." In addition, in the required values ​​of the center of gravity 3 mode, the roll moment M r , pitch moment M p , and the heave force F h The required values ​​for each of these are expressed as the required roll moment M r , required pitch moment M p , and the required heave force F h Also called.

[0015] In the behavior model of the vehicle 10 shown in FIG. 1, the suspension 20RLA that suspends the left rear wheel 14RL is configured as an active suspension including an actuator 26RL. The suspension 20RRA that suspends the right rear wheel 14RR is also configured as an active suspension including an actuator 26RR. The suspension 20FRA that suspends the right front wheel 14FR is also configured as an active suspension including an actuator 26FR. The suspensions 20FRA, 20RRA, and 20RLA are so-called full active suspensions that can actively apply vertical control forces to the wheels 14FR, 14RR, and 14RL by the actuators 26FR, 26RR, and 26RL. On the other hand, the suspension 20FL that suspends the front left wheel 14FL is a general suspension that does not have an actuator, that is, a non-active suspension.

[0016] In the behavior model shown in FIG. 1, the control force F applied to the left rear wheel 14RL by the actuator 26RL is rl and the control force F applied to the right rear wheel 14RR by the actuator 26RR. rr and the control force F applied to the right front wheel 14FR by the actuator 26FR. fr In the following, the wheels provided with the active suspension are also referred to as "controlled wheels." That is, in the behavior model shown in FIG 1, the left rear wheel 14RL, the right rear wheel 14RR, and the right front wheel 14FR are controlled wheels.

[0017] The inventors of the present disclosure have found that the required values ​​of the three center-of-gravity modes can be converted into control forces for each controlled wheel by the following formula (2).

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[0018] As described above, since the required value of the behavior parameter can be converted into the required value of the three center of gravity modes, the required value of the behavior parameter can be converted into the control force for each controlled wheel. Hereinafter, the control force for each controlled wheel obtained by converting the required value of the behavior parameter is also referred to as the "required control force." Then, the required value of the behavior parameter can be realized by controlling each actuator 26RL, 26RR, 26FR so as to satisfy the required control force. In other words, the desired vehicle behavior can be realized with only three actuators 26RL, 26RR, 26FR. The ability to reduce the number of actuators required is preferable from the viewpoints of improved mountability, cost reduction, weight reduction, power saving, and the like.

[0019] It is also possible to realize the above-described behavior control of the vehicle 10 by "torque control" of each of the actuators 26RL, 26RR, and 26FR. However, in the case of torque control, a force sensor, a torque sensor, and the like are required. Therefore, in this embodiment, in order to further reduce the mounting space and cost, a method of realizing the above-described behavior control by "position control" of each of the actuators 26RL, 26RR, and 26FR is proposed. Hereinafter, a vehicle behavior control device that controls the behavior of the vehicle 10 by position control of each of the actuators 26RL, 26RR, and 26FR will be described in detail.

[0020] 1.2 Vehicle behavior control device FIG. 2 is a diagram for explaining the configuration of the vehicle behavior control device according to the first embodiment.

[0021] 2, vehicle 10 has a front axle 16F equipped with a left front wheel 14FL and a right front wheel 14FR that are steered wheels, and a rear axle 16R equipped with a left rear wheel 14RL and a right rear wheel 14RR that are non-steered wheels. However, rear wheels 14RL, 14RR may also be provided with a steering mechanism. Vehicle 10 may be a front-wheel drive vehicle that drives front wheels 14FL, 14FR, a rear-wheel drive vehicle that drives rear wheels 14RL, 14RR, or an all-wheel drive vehicle that drives front wheels 14FL, 14FR and rear wheels 14RL, 14RR.

[0022] The vehicle behavior control device includes a suspension 20RLA (hereinafter also referred to as the "first suspension 20RLA") provided on the left rear wheel 14RL (first wheel), a suspension 20RRA (hereinafter also referred to as the "second suspension 20RRA") provided on the right rear wheel RR (second wheel), a suspension 20FRA (hereinafter also referred to as the "third suspension 20FRA") provided on the right front wheel 14FR (third wheel), a suspension 20FL (hereinafter also referred to as the "fourth suspension 20FL") provided on the left front wheel 14FL (fourth wheel), a controller 30, and a sensor group 40. As described above, the first suspension 20RLA, the second suspension 20RRA, and the third suspension 20FRA are active suspensions, and the fourth suspension 20FL is a non-active suspension.

[0023] The fourth suspension 20FL, which is an inactive suspension, includes a spring 22FL and a shock absorber 24FL. The first suspension 20RLA, which is an active suspension, includes an actuator 26RL (hereinafter also referred to as "first actuator 26RL") in addition to the spring 22RL and shock absorber 24RL.

[0024] Similarly, the second suspension 20RRA, which is an active suspension, includes an actuator 26RR (hereinafter also referred to as "second actuator 26RR") in addition to a spring 22RR and a shock absorber 24RR. Similarly, the third suspension 20FRA, which is an active suspension, includes an actuator 26FR (hereinafter also referred to as "third actuator 26FR") in addition to a spring 22FR and a shock absorber 24FR.

[0025] The controller 30 is connected to the sensor group 40 via an in-vehicle network such as a controller area network (CAN). The controller 30 acquires signals from the sensor group 40. The sensor group 40 includes sensors that measure physical quantities related to the behavior of the vehicle 10, such as an acceleration sensor, a vehicle height sensor, and a wheel speed sensor. The controller 30 is also connected to each of the actuators 26RL, 26RR, and 26FR via the in-vehicle network.

[0026] The controller 30 includes a processor 32 and a memory 34 coupled to the processor 32 .

[0027] The processor 32 executes various processes. The processor 32 can be configured, for example, by a central processing unit (CPU) including an arithmetic unit and a register, a graphics processing unit (GPU), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), etc. The memory 34 stores various information required for the processor 32 to execute processes. The memory 34 can be configured, for example, by a recording medium such as a read only memory (ROM), a random access memory (RAM), a hard disk drive (HDD), or a solid state drive (SSD).

[0028] The memory 34 stores a computer program 36 executable by the processor 32 and various information related to the computer program 36. The functions of the controller 30 are realized by cooperation between the processor 32, which executes the computer program 36, and the memory 34. The computer program 36 may be recorded in a computer-readable recording medium. The computer program 36 may also be distributed over the air (OTA).

[0029] The controller 30 controls each of the actuators 26RL, 26RR, and 26FR based on signals acquired from the sensor group 40. In particular, the controller 30 calculates a position control amount for each of the actuators 26RL, 26RR, and 26FR by executing processing, and transmits the calculated position control amount to each of the actuators 26RL, 26RR, and 26FR. That is, the controller 30 controls the position of each of the actuators 26RL, 26RR, and 26FR. The position control amount may be an amount that gives a target position, or an amount that gives a movement amount from a current position. Details of the processing executed by the controller 30 according to the first embodiment will be described later.

[0030] Each of the actuators 26RL, 26RR, 26FR operates according to a position control amount received from the controller 30. Each of the actuators 26RL, 26RR, 26FR is configured such that the control force applied to the corresponding controlled wheel changes depending on the controlled position.

[0031] Such an actuator may take various forms. Fig. 3 is a diagram for explaining an example of the configuration of the actuator 26 according to the first embodiment. In Fig. 3, an active suspension 20A including the actuator 26 is shown.

[0032] 3, a spring 22 and a damper 24 are provided between the vehicle body 12 and an unsprung member 21 (e.g., a suspension arm). The spring 22 generates a reaction force according to the stroke amount of the active suspension 20A.

[0033] The actuator 26 shown in Fig. 3 includes a motor 28 supported by the sprung structure, and a torsion bar 27 having one end connected to the output shaft of the motor 28. The other end of the torsion bar 27 is connected to the unsprung member 21 via a link mechanism 29. The operation of the motor 28 is controlled by a controller 30. Particularly in this embodiment, the controller 30 controls the position of the motor 28. Therefore, in this case, the position of the actuator 26 indicates the angle of the motor 28. The position control amount is the target angle or rotation angle amount of the motor 28.

[0034] When the motor 28 rotates under the control of the controller 30, the torsion bar 27 deforms, and the reaction force of the torsion bar 27 is converted into a vertical force via the link mechanism 29 and transmitted to the unsprung member 21 and the wheel 14. In this way, the actuator 26 can actively apply a vertical control force to the unsprung member 21 and the wheel 14 by deforming the torsion bar 27. Furthermore, when the vehicle 10 is accelerated / decelerated, steered, or the like, an external force input from the unsprung member 21 side is transmitted to the output shaft of the motor 28 via the link mechanism 29 and the torsion bar 27. It can also be said that the torsion bar 27 and the link mechanism 29 are transmission members that transmit forces between the motor 28 and the unsprung member 21 and the wheel 14.

[0035] The actuator 26 according to this embodiment can be configured as described above. In the vehicle behavior control device according to this embodiment, the configuration of the actuator 26 described in Fig. 3 can be applied to each of the actuators 26RL, 26RR, and 26FR. However, the configuration of the actuator 26 described in Fig. 3 is only an example, and other configurations can also be applied.

[0036] For example, the actuator 26 may be composed of a coil spring, one end of which is connected to the unsprung member 21, and a linear motor that operates to expand and contract the coil spring. In this case, when the linear motor operates under the control of the controller 30, the coil spring is deformed, and the reaction force of the coil spring is transmitted to the unsprung member 21 and the wheel 14. The coil spring can also be said to be a transmission member that transmits force between the linear motor, the unsprung member 21, and the wheel 14. In this case, the position of the actuator 26 indicates, for example, the position on the guide of the movable part of the linear motor. The position control amount is, for example, the target position or movement amount of the movable part on the guide.

[0037] For example, the actuator 26 may be composed of a motor supported on the sprung structure, a ball screw nut rotated by the output of the motor, a ball screw shaft that moves in the axial direction by the rotation of the ball screw nut, and a piston rod one end of which is connected to the ball screw shaft. The other end of the piston rod is connected to the unsprung member 21 via a cylinder. In this case, when the motor rotates under the control of the controller 30, the ball screw nut rotates, and the axial force of the ball screw shaft and the piston rod is transmitted to the unsprung member 21 and the wheel 14. The ball screw nut, the ball screw shaft, and the piston rod can also be said to be transmission members that transmit force between the motor, the unsprung member 21, and the wheel 14.

[0038] Incidentally, the transmission members such as the torsion bar 27 can be considered as elastic members having a certain rigidity. Also, the motor 28 can be considered to be fastened to a part of the vehicle body 12, a suspension member, etc. Therefore, the actuator 26 shown in FIG. 3 can be modeled as a spring element connected in parallel with the spring 22.

[0039] Fig. 4 is a diagram showing the active suspension 20A modeled with respect to spring elements. In Fig. 4, Ks indicates the stiffness of the spring 22, and Kb indicates the stiffness of the torsion bar 27. z1 and z2 indicate the unsprung and sprung displacements, respectively, with the upward direction in the drawing being the positive direction. That is, in the model shown in Fig. 4, z2-z1 is the stroke amount of the active suspension 20A. In the following explanation, the torsion bar 27 may be replaced with another transmission member depending on the configuration of the actuator 26.

[0040] The spring element associated with the torsion bar 27 generates a reaction force corresponding to at least the stroke amount. Furthermore, it can be considered that the spring element associated with the torsion bar 27 generates a reaction force corresponding to the relative displacement zΔ due to the position control of the actuator 26. In the model shown in FIG. 4, zΔ is positive in the direction in which the spring element extends. In the model shown in FIG. 4, the force F generated by the actuator 26 is expressed by the following formula (3). The force F corresponds to the control force applied to the wheel 14 by the actuator 26. Even if the position command for the actuator 26 (motor 28) is zero, i.e., even if the relative displacement zΔ is zero, the actuator 26 generates a force F corresponding to the stroke amount (z2-z1).

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[0041] 1.3 Behavior Control In the following, a process executed by the controller 30, more specifically, a process executed by the processor 32, in the behavior control of the vehicle 10 according to the first embodiment will be described. Fig. 5 is a flowchart showing an example of the process executed by the controller 30 according to the first embodiment. The process according to the flowchart shown in Fig. 5 may be repeatedly executed at a predetermined processing cycle.

[0042] In step S110, the controller 30 calculates the required value of the behavior parameter. Alternatively, the controller 30 may obtain the required value of the behavior parameter from another device. In the first embodiment, the behavior parameter is a vertical control force for each wheel. That is, in step S110, the controller 30 calculates the vertical control force F rli , the vertical control force F rri , the vertical control force F fli , and the vertical control force F fri As described above, in this embodiment, the method of calculating the required values ​​of the behavior parameters is not particularly limited.

[0043] Next, in step S120, the controller 30 converts the required value of the behavior parameter into a required value for the center of gravity 3 mode. The controller 30 converts the required value of the behavior parameter into a required roll moment M r , required pitch moment M p , and the required heave force F h can be converted to

[0044] Next, in step S130, the controller 30 further converts the required value of the center of gravity 3 mode into a required control force for each controlled wheel. The controller 30 converts the required roll moment M r , required pitch moment M p , and the required heave force F h , the required control force F rl (hereinafter, also referred to as the "first required control force"), the required control force F rr (hereinafter, also referred to as the "second required control force"), and the required control force F fr (hereinafter also referred to as the "third required control force").

[0045] Next, in step S140, the controller 30 calculates the stroke amount (first required stroke amount) of the first suspension 20RLA, the stroke amount (second required stroke amount) of the second suspension 20RRA, and the stroke amount (third required stroke amount) of the third suspension 20FRA when the required values ​​of the behavior parameters are satisfied. Each required stroke amount can be considered as the stroke amount that each active suspension should satisfy in the behavior control of the vehicle 10.

[0046] Since the vertical control force for each wheel is proportional to the stroke of each suspension, the stroke of each suspension can be calculated by the following formula (4). srl , z srr , z sfr , and z sfl are the stroke amounts of the first suspension 20RLA, the second suspension 20RRA, the third suspension 20FRA, and the fourth suspension 20FL, respectively. r and K f are proportionality constants for the rear axle 16R and the front axle 16F, respectively. K r and K f is a constant that can be determined from the specification information of the vehicle 10 and the state of the vehicle 10.

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[0047] Therefore, the controller 30 uses the formula (4) to calculate F as the required value of the behavior parameter. rli The required value of F rri The required value of F fri From the required value of the first required stroke amount z srl , second required stroke amount z srr , and the third required stroke amount z sfl can be calculated.

[0048] Next, in step S150, the controller 30 calculates the position control amount of each of the actuators 26RL, 26RR, 26FR that satisfies the required control force for each controlled wheel. That is, the controller 30 calculates the position control amount (first position control amount) of the first actuator 26RL that corresponds to the first required control force, the position control amount (second position control amount) of the second actuator 26RR that corresponds to the second required control force, and the position control amount (third position control amount) of the third actuator 26FR that corresponds to the third required control force. The controller 30 calculates each required stroke amount (first required stroke amount z srl , second required stroke amount z srr , and the third required stroke amount z sfl ), the first position control amount, the second position control amount, and the third position control amount can be calculated as follows.

[0049] As described in FIG. 4, the control force applied to the wheel 14 by the actuator 26 can be expressed by the above formula (3) from the stroke amount and the relative displacement due to the position control. Therefore, the controller 30 uses formula (3) to calculate the first required stroke amount z srl Based on this, the first required control force F rl The relative displacement of the first actuator 26RL (hereinafter, also referred to as the "first required relative displacement") that can obtain the above equation (3) can be calculated by adding the first required stroke amount z srl Substituting the first required control force F into the force F rl By substituting, the first required relative displacement zΔ rl is expressed by the following equation (5).

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[0050] Similarly, by using equation (3), the controller 30 calculates the second required stroke amount z srr and the third required stroke amount z sfl Based on this, the second required control force F rrThe relative displacement zΔ of the second actuator 26RR (hereinafter also referred to as the "second required relative displacement") rr and the third required control force F fr The relative displacement zΔ of the third actuator 26FR that satisfies the above requirement (hereinafter, also referred to as the "third required relative displacement") fr and can be calculated.

[0051] 4, the relative displacement zΔ is an amount that has a certain correspondence with the position of the actuator 26. In other words, if the correspondence between the relative displacement zΔ and the position of the actuator 26 is known, the relative displacement zΔ can be converted into the position of the actuator 26.

[0052] The correspondence between the relative displacement zΔ and the position of the actuator 26 can be determined from the design values ​​of the active suspension 20A and the actual measured values ​​obtained by testing. For example, when the actuator 26 has the configuration shown in FIG. 3, the vehicle 10 is kept stationary and the motor 28 is rotated, and the angle θ of the motor 28 (the position of the actuator 26) and the stroke amount z of the active suspension 20A are calculated. s Consider a case where a test is conducted to measure the coefficient A in the following equation (6). In this case, the relationship in the following equation (7) is established.

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[0053] Therefore, by determining the coefficient A through testing, the correspondence relationship between the relative displacement zΔ and the angle θ of the motor 28 (position of the actuator 26) can be expressed by the following formula (8). In other words, the relative displacement zΔ can be converted into the angle of the motor 28 (position of the actuator 26) by formula (8).

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[0054] The correspondence relationship between the relative displacement zΔ and the position of the actuator 26 may be stored in the memory 34 as a function formula or mapping information, or may be recorded as a part of the computer program 36.

[0055] In this way, based on the correspondence between the relative displacement zΔ and the position of the actuator 26, the controller 30 calculates the first required relative displacement zΔ rl can be converted into the position of the first actuator 26RL. Then, the controller 30 calculates the first position control amount so as to indicate the converted position of the first actuator 26RL. Similarly, the controller 30 calculates the second required relative displacement zΔ rr and the third required relative displacement zΔ fr can be converted into the positions of the second actuator 26RR and the third actuator 26FR, respectively. Furthermore, the controller 30 may calculate the second position control amount and the third position control amount so as to indicate the converted positions of the second actuator 26RR and the third actuator 26FR.

[0056] In this manner, the controller 30 can calculate the first position control amount, the second position control amount, and the third position control amount based on each required stroke amount so that the required control force for each controlled wheel can be obtained.

[0057] Next, in step S160, the controller 30 performs position control of the first actuator 26RL, the second actuator 26RR, and the third actuator 26FR in accordance with the calculated first position control amount, second position control amount, and third position control amount. As a result, the first required control force F rl , the second required control force F rr , and the third required control force F fr Thus, the actuators 26RL, 26RR, and 26FR can be controlled to satisfy the above. As a result, the required values ​​of the behavior parameters can be realized. After step S160, the controller 30 ends the current process.

[0058] The functions of the vehicle behavior control device according to the first embodiment are realized by the controller 30 executing the processes in this manner. The vehicle behavior control method according to the first embodiment is realized by the controller 30 executing the processes in this manner. The vehicle behavior control program according to the first embodiment is realized by the computer program 36 that causes the controller 30 to execute the processes in this manner.

[0059] 1.4 Correction of requirements In the example shown in FIG. 3, each of the actuators 26RL, 26RR, and 26FR includes a transmission member such as a torsion bar 27 that transmits a reaction force generated by deformation as a control force. Then, each of the actuators 26RL, 26RR, and 26FR applies a vertical control force to each controlled wheel by deforming the transmission member. When the configuration shown in FIG. 3 is adopted, each of the actuators 26RL, 26RR, and 26FR outputs a control force corresponding to the reaction force of the transmission member according to the stroke amount even if the relative displacement zΔ is zero. For example, a stroke amount occurs when the vehicle 10 turns or accelerates or decelerates. Therefore, even if the relative displacement zΔ is zero, each of the actuators 26RL, 26RR, and 26FR outputs a control force corresponding to the reaction force of the transmission member according to the stroke amount.

[0060] On the other hand, in the vehicle behavior control device according to the first embodiment, the fourth suspension 20FL provided on the left front wheel 14FL does not include an actuator. That is, the fourth suspension 20FL does not include a transmission member such as a torsion bar 27. Therefore, the fourth suspension 20FL does not generate a reaction force equivalent to the reaction force of the transmission member generated in the other suspensions. This may cause problems in the posture of the vehicle 10 during steering or acceleration / deceleration. This means that the suspension 20FL of the left front wheel 14FL is "softer" than the suspensions 20FR, 20RL, and 20RR of the other wheels 14FR, 14RL, and 14RR. That is, an imbalance in suspension stiffness occurs between the left front wheel 14FL and the other wheels 14FR, 14RL, and 14RR. Such an imbalance in suspension stiffness causes abnormal or uncomfortable inclination of the vehicle body during acceleration / deceleration and steering. In addition, an imbalance in suspension stiffness causes a decrease in control performance, excessive oversteer or understeer, and the like.

[0061] For example, consider a case where the required relative displacement for each of the actuators 26RL, 26RR, 26FR is zero when the vehicle 10 is decelerated by braking. In this case, the suspensions other than the fourth suspension 20FL output a control force equivalent to the reaction force of the transmission member, so the stroke amount becomes small. On the other hand, the fourth suspension 20FL does not generate a reaction force equivalent to the reaction force of the transmission member, so the stroke amount becomes large. As a result, the left front wheel 14FL may sink more than the other wheels, and the vehicle 10 may assume a posture that is tilted in the roll direction. In addition, for example, when the vehicle 10 turns, the left front wheel 14FL may sink more when turning right, while the right front wheel 14FR may not sink as much as the left front wheel 14FL when turning left, so that the posture of the vehicle 10 may differ depending on the direction of turning.

[0062] To address the above-mentioned issues, the vehicle behavior control device according to this embodiment may correct the required value of the behavior parameter by assuming that the fourth suspension 20FL includes a transmission member such as the torsion bar 27. In other words, the required value of the behavior parameter is corrected so as to realize a behavior of the vehicle 10 in which it can be assumed that the reaction force of the transmission member is also generated in the fourth suspension 20FL. The required value of the behavior parameter can be corrected based on a virtual reaction force value applied to the left front wheel 14FL by a transmission member assumed to be included in the fourth suspension 20FL.

[0063] Here, the virtual reaction force value can be calculated as follows, for example, when the transmission member is the torsion bar 27.

[0064] First, regarding acceleration and deceleration, the suspension force share F of the left front wheel 14FL excluding the suspension link reaction force is flx is calculated using the following formula (9).

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[0065] Here, each parameter is defined as follows: H: Height of center of gravity above spring l:Wheelbase m: sprung mass a xp : Acceleration side of front and rear G a xm : Deceleration side of front and rear G α xp : Front drive force distribution α xm :Front braking force distribution α k : Front regeneration ratio tan θ I : Suspension link inclination angle in side view relative to wheel center (point I) tan θ J : Suspension link inclination angle in side view relative to tire contact point (point J)

[0066] In the above formula (9), the driving force and the regenerative force act on point I. The longitudinal G of the vehicle 10 may be estimated based on the required torque and required force of the engine and the drive motor, and the required force of the brakes and regeneration. Alternatively, it may be obtained by a sensor.

[0067] Next, regarding steering, the suspension share force F of the left front wheel 14FL excluding the suspension link reaction force is fly is calculated using the following formula (10).

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[0068] Here, each parameter is defined as follows: β: Vehicle slip angle V:Vehicle speed r: Yaw rate γ: Weighted movement distribution ratio of the front a y : Horizontal G C pf : Front wheel cornering power tan θ y : Rear view of suspension link inclination

[0069] The lateral G of the vehicle 10 may be estimated from the steering angle, the vehicle speed, etc. Alternatively, it may be obtained by a sensor.

[0070] The left front wheel 14FL suspension force distribution F flx and the left front wheel 14FL suspension force distribution F fly From the above, the virtual reaction force value can be calculated by the following formula (11). Here, K bf is the assumed stiffness of the torsion bar 27 (including the bushing effect and link efficiency), K sf is the upper and lower stiffness of the suspension (excluding the 27% torsion bar).

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[0071] In the first embodiment, the required value of the behavior parameter is the required value of the control force in the vertical direction for each wheel. Therefore, in the first embodiment, the required value of the behavior parameter can be corrected by adding the virtual reaction force value calculated by the formula (11) to the required value of the control force in the vertical direction for the left front wheel FL. In other words, in the required value of the behavior parameter after correction, the required value of the control force in the vertical direction for the left front wheel FL is calculated by adding F' in the following formula (12): rli In formula (12), F rli indicates the required value before correction.

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[0072] The controller 30 can be configured to execute the process according to the flowchart shown in FIG. 6 after calculating the required value of the behavior parameter (step S110 in FIG. 5).

[0073] In step S111, the controller 30 calculates a virtual reaction force value applied to the left front wheel FL by the transmission member assumed to be included in the fourth suspension 20FL, assuming that the fourth suspension 20FL includes a transmission member such as the torsion bar 27. For example, the controller 30 can calculate the virtual reaction force value using the above equations (9)-(11).

[0074] Next, in step S112, the controller 30 corrects the required value of the behavior parameter based on the calculated virtual reaction force value. In the first embodiment, the controller 30 corrects the required value of the behavior parameter by adding the virtual reaction force value to the required value of the vertical control force for the left front wheel FL, as shown in equation (12).

[0075] After step S112, the process may proceed to step S120 in Fig. 5. At this time, the required value of the behavior parameter becomes the corrected required value.

[0076] 1.5 Effects As described above, according to the first embodiment, the three active suspensions 20RLA, 20RRA, and 20FRA can be used to achieve controllability equivalent to that achieved when an active suspension is provided on each wheel in terms of behavior control of a four-wheeled vehicle 10. This allows the number of actuators required to be reduced, thereby improving mountability, reducing costs, reducing weight, and saving power, and the like. Furthermore, according to the first embodiment, the actuators 26RL, 26RR, and 26FR are controlled by position control. In other words, force sensors, torque sensors, and the like are not required, and the mounting space and costs of the actuators 26RL, 26RR, and 26FR can be reduced. This in turn allows for further improvement in mountability and cost reduction.

[0077] In the above embodiment, the suspension 20FL provided on the left front wheel 14FL is an inactive suspension, but in the vehicle behavior control device according to the first embodiment, it is possible to arbitrarily determine which three of the four wheels are to be provided with active suspensions. For example, it is also possible to use an inactive suspension for the suspension 20RRA provided on the right rear wheel 14RR, and active suspensions for the suspensions 20RLA, 20FL, and 20FRA provided on the other wheels 14RL, 14FL, and 14FR.

[0078] 2. Second embodiment The vehicle behavior control device according to the second embodiment will be described below. In the following description, the differences from the first embodiment will be mainly described, and the contents common to the first embodiment will be omitted as appropriate.

[0079] 2.1 Behavior Control The behavior control of the vehicle 10 by the vehicle behavior control device according to the second embodiment is performed based on the behavior model shown in Fig. 1, as in the first embodiment. However, in the second embodiment, three center of gravity modes are adopted as the behavior parameters. In other words, the required value of the behavior parameter according to the second embodiment is the required roll moment M r , required pitch moment M p , and the required heave force Fh The required values ​​of the behavior parameters are directly the required values ​​of the three center of gravity modes.

[0080] The configuration of the vehicle behavior control device according to the second embodiment may be equivalent to the configuration described in Fig. 2. Below, the processing executed by the controller 30, more specifically, the processing executed by the processor 32, in the behavior control of the vehicle 10 according to the second embodiment will be described. Fig. 7 is a flowchart showing an example of the processing executed by the controller 30 according to the second embodiment. The processing according to the flowchart shown in Fig. 7 may be repeatedly executed at a predetermined processing cycle.

[0081] In step S210, the controller 30 calculates the required value of the behavior parameter. Alternatively, the controller 30 may obtain the required value of the behavior parameter from another device. In the second embodiment, the behavior parameter is a roll moment M r , pitch moment M p , and the heave force F h That is, in step S210, the controller 30 calculates the required roll moment M r , required pitch moment M p , and the required heave force F h Similarly to the first embodiment, the method of calculating the required value of the behavior parameter is not particularly limited.

[0082] Next, in step S230, the controller 30 converts the required value of the center of gravity 3 mode into a required control force for each controlled wheel. The process of step S230 is the same as the process of step S130 described with reference to FIG.

[0083] Next, in step S240, the controller 30 calculates a first required stroke amount, a second required stroke amount, and a third required stroke amount when the required value of the behavior parameter is satisfied.

[0084] As explained in the first embodiment, the stroke amount of each suspension can be calculated from the control force for each wheel using the above formula (4). On the other hand, in the second embodiment, the required value of the behavior parameter is the required value of the center of gravity 3 mode. Therefore, the controller 30 first converts the required value of the center of gravity 3 mode into the control force for each wheel using the following formula (13). Hereinafter, the value of the control force for each wheel obtained by converting the required value of the center of gravity 3 mode will be referred to as the "converted required value." In formula (13), F rlz is the conversion requirement for the control force on the left rear wheel, F rrz is the conversion requirement for the control force on the right rear wheel, F flz is the conversion requirement for the control force on the left front wheel, F frz is the conversion requirement for the control force for the right front wheel.

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[0085] The controller 30 then calculates the first required stroke amount z srl , second required stroke amount z srr , and the third required stroke amount z sfl can be calculated.

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[0086] Next, in step S250, the controller 30 calculates the position control amount of each of the actuators 26RL, 26RR, 26FR that satisfies the required control force for each controlled wheel. The process of step S230 is the same as the process of step S150 described with reference to FIG.

[0087] Next, in step S260, the controller 30 performs position control of the first actuator 26RL, the second actuator 26RR, and the third actuator 26FR in accordance with the calculated first position control amount, second position control amount, and third position control amount. This allows the required values ​​of the behavior parameters to be realized. After step S260, the controller 30 ends this processing.

[0088] The functions of the vehicle behavior control device according to the second embodiment are realized by the controller 30 executing the processes in this manner. The vehicle behavior control method according to the second embodiment is realized by the controller 30 executing the processes in this manner. The vehicle behavior control program according to the second embodiment is realized by the computer program 36 that causes the controller 30 to execute the processes in this manner.

[0089] 2.2 Correction of required values In the second embodiment, as in the first embodiment, the required value of the behavior parameter can be corrected by assuming that the fourth suspension 20FL includes a transmission member such as a torsion bar 27. As in the first embodiment, the required value of the behavior parameter can be corrected based on a virtual reaction force value applied to the left front wheel 14FL by a transmission member assumed to be included in the fourth suspension 20FL. The virtual reaction force value F flxy can be calculated using the above equations (9)-(11).

[0090] In the second embodiment, the required value of the behavior parameter is the required roll moment M r , required pitch moment M p , and the required heave force F h Therefore, in the second embodiment, a virtual reaction force value F is first calculated by the following formula (15). flxy is converted to the center of gravity 3 mode. In the following, the virtual reaction force value F flxy The values ​​of the three modes of the center of gravity obtained by the conversion are called "converted reaction force values." In equation (15), M rflxy is the converted reaction force value related to the roll moment, M pflxy is the converted reaction force value related to the pitch moment, Fhflxy is the converted reaction force value related to the heave force.

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[0091] The required value of the behavior parameter is corrected by converting the converted reaction force obtained by equation (16) into the required roll moment M r , required pitch moment M p , and the required heave force F h That is, in the required values ​​of the corrected behavior parameters, the required roll moment, the required pitch moment, and the required heave force are respectively calculated by adding M' r , M' p , and F' h In formula (15), M r , M p , and F h are the roll moment, pitch moment, and heave force before correction, respectively.

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[0092] As in the first embodiment, the controller 30 can be configured to execute the process according to the flowchart shown in FIG. 6 after calculating the required value of the behavior parameter (step S210 in FIG. 7). In the second embodiment, in step S112, the controller 30 calculates a converted reaction force value by converting the virtual reaction force value into the center of gravity 3 mode as shown in equations (15)-(16), and converts the converted reaction force value into a required roll moment M r , required pitch moment M p , and the required heave force F h After step S112, the process may proceed to step S230 in Fig. 7. At this time, the required value of the behavior parameter becomes the corrected required value.

[0093] 2.5 Effects As can be understood from the above description, the second embodiment can also achieve the same functions and effects as the first embodiment.

[0094] Although the embodiments have been described in detail above, these embodiments merely show specific examples of implementing the technology according to the present disclosure. Therefore, the technical scope of the present disclosure is not limited to the above-mentioned embodiments. The technology according to the present disclosure can be modified in various ways without departing from the spirit of the technology, and these modifications are also included in the technical scope of the present disclosure. [Explanation of symbols]

[0095] 10 vehicles, 30 controllers, 32 processors, 34 memories, 36 Computer Program, 20RLA 1st Suspension, 20RRA 2nd suspension, 20FRA 3rd suspension, 20FL 4th suspension, 26RL 1st actuator, 26RR 2nd actuator, 26FR 3rd actuator, 27 Torsion bar

Claims

1. an ith suspension provided on an ith wheel (i=1, 2, 3) among four wheels of a vehicle; a fourth suspension provided on a fourth wheel other than the i-th wheel; A controller; Equipped with the i-th suspension includes an i-th actuator whose position is controlled by the controller, The controller: obtaining a required value of a behavior parameter that determines a behavior of the vehicle; converting the required value of the behavior parameter into an i-th required control force for the i-th wheel; calculating an ith position control amount of the ith actuator based on the ith required control force; The position control of the i-th actuator is performed in accordance with the i-th position control amount. It was configured as Vehicle behavior control device.

2. The vehicle behavior control device according to claim 1, The fourth suspension does not include an actuator controlled by the controller. Vehicle behavior control device.

3. The vehicle behavior control device according to claim 1, The controller further comprises: calculating an ith required stroke amount of the ith suspension when the required value of the behavior parameter is satisfied; The i-th position control amount is calculated based on the i-th required stroke amount so that the i-th required control force is obtained. It was configured as Vehicle behavior control device.

4. The vehicle behavior control device according to claim 3, the behavior parameter is a control force for each of the i-th wheel and the fourth wheel, The controller further comprises: The i-th required stroke amount of the i-th suspension, which corresponds to the required value related to the control force for the i-th wheel, is calculated. It was configured as Vehicle behavior control device.

5. The vehicle behavior control device according to claim 3, The behavior parameters are a roll moment, a pitch moment, and a heave force acting on a center of gravity of the vehicle, The controller further comprises: converting the demand values ​​for the roll moment, the pitch moment, and the heave force into converted demand values ​​for control forces for each of the i-th wheel and the 4th wheel; Calculating the i-th required stroke amount of the i-th suspension, which corresponds to the conversion required value related to the control force for the i-th wheel It was configured as Vehicle behavior control device.

6. A vehicle behavior control device according to any one of claims 1 to 5, the i-th actuator includes a transmission member that transmits a reaction force generated by deformation as a control force; The i-th actuator applies a vertical control force to the i-th wheel by deforming the transmission member. It was configured as Vehicle behavior control device.

7. The vehicle behavior control device according to claim 6, The transmission member is a torsion bar. Characterized by Vehicle behavior control device.

8. The vehicle behavior control device according to claim 6, the fourth suspension does not include an actuator controlled by the controller; The controller further comprises: Assuming that the fourth suspension includes the transmission member, calculating a virtual reaction force value applied to the fourth wheel by the transmission member assumed to be included in the fourth suspension; The required value is corrected based on the virtual reaction force value. It was configured as Vehicle behavior control device.

9. The vehicle behavior control device according to claim 8, the behavior parameter is a control force for each of the i-th wheel and the fourth wheel, The controller further comprises: The required value for the control force for the fourth wheel is corrected by adding the virtual reaction force value to the required value. It was configured as Vehicle behavior control device.

10. The vehicle behavior control device according to claim 8, The behavior parameters are a roll moment, a pitch moment, and a heave force acting on a center of gravity of the vehicle, The controller further comprises: converting the virtual reaction force values ​​into converted reaction force values ​​relating to the roll moment, the pitch moment, and the heave force; correcting the demand values ​​for the roll moment, the pitch moment, and the heave force by adding the converted reaction force value to the demand values; It was configured as Vehicle behavior control device.

11. A vehicle behavior control method for controlling a vehicle behavior by a computer, comprising: The vehicle is an ith suspension provided on an ith wheel (i=1, 2, 3) among the four wheels; a fourth suspension provided on a fourth wheel other than the i-th wheel; Equipped with the i-th suspension includes an i-th actuator that is position-controlled; The vehicle behavior control method includes: Obtaining a required value of a behavior parameter that determines a behavior of the vehicle; converting the required value of the behavior parameter into an i-th required control force for the i-th wheel; calculating an ith position control amount of the ith actuator based on the ith required control force; performing the position control of the i-th actuator in accordance with the i-th position control amount; Includes A vehicle behavior control method.

12. A vehicle behavior control program for causing a computer to control a vehicle behavior, The vehicle is an ith suspension provided on an ith wheel (i=1, 2, 3) among the four wheels; a fourth suspension provided on a fourth wheel other than the i-th wheel; Equipped with the i-th suspension includes an i-th actuator that is position-controlled; The vehicle behavior control program includes: A process of obtaining a required value of a behavior parameter that determines a behavior of the vehicle; A process of converting the required value of the behavior parameter into an i-th required control force for the i-th wheel; A process of calculating an i-th position control amount of the i-th actuator based on the i-th required control force; performing the position control of the i-th actuator in accordance with the i-th position control amount; causing the computer to execute Vehicle behavior control program.

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