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

Abstract

The present disclosure provides a technology that makes it possible to reduce costs relating to a vehicle behavior control device. A vehicle behavior control device according to the present disclosure comprises: an i-th suspension that is provided to an i-th wheel (i = 1, 2, 3) among four wheels of the vehicle; a fourth suspension that is provided to the fourth wheel, which is not an i-th wheel; and a controller. The i-th suspension includes an i-th actuator, the position of which is controlled by the controller. The controller is configured so as to acquire a requested value of a behavior parameter for determining the behavior of the vehicle, convert the requested value of the behavior parameter into an i-th requested control force for the i-th wheel; calculate an i-th position control quantity of the i-th actuator, said i-th position control quantity being based on the i-th requested control force; and control the position of the i-th actuator in accordance with the i-th position control quantity.

Description

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

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

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

[0003] Japanese Patent Publication No. 2023-047810

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

[0005] In view of the above-mentioned problems, one object of the present disclosure is to provide a technology that enables cost reduction in relation to vehicle behavior control.

[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) of 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 for the ith actuator based on the ith required control force, and control the position of the ith actuator in accordance with the ith position control amount.

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

[0009] FIG. 1 is a diagram showing a behavior model for vehicle behavior control by a vehicle behavior control device according to an embodiment. FIG. 2 is a diagram for explaining the configuration of the vehicle behavior control device according to an embodiment. FIG. 3 is a diagram showing an example of the configuration of an actuator according to an embodiment. FIG. 4 is a diagram showing an active suspension according to an embodiment modeled in terms of spring elements. FIG. 5 is a flowchart showing processing executed in the behavior control device according to the first embodiment. FIG. 6 is a flowchart showing processing executed regarding correction of a required value of a behavior parameter. FIG. 7 is a flowchart showing processing executed in the behavior control device according to a second embodiment.

[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 the 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, vertical control forces for each wheel are used as the behavior parameters. The behavior model shown in FIG. 1 includes a vertical control force F for the left rear wheel 14RL. ｒli and a vertical control force F ｒri and a vertical control force F fli and a vertical control force F fri and are illustrated.

[0011] Various types of control are conceivable for the behavior control of the vehicle 10 depending on the purpose. Examples of behavior control of the vehicle 10 include sprung feedback control, unsprung feedback control, preview control, and attitude control. The sprung feedback control suppresses vibrations in the sprung mass based on a sprung mass state quantity calculated using the measurement values ​​of a sprung mass acceleration sensor. The unsprung mass feedback control suppresses vibrations in the unsprung mass based on an unsprung mass state quantity calculated using the measurement values ​​of a sprung mass acceleration sensor and a vehicle height sensor. The preview control predicts road surface conditions using a database of camera images and high-precision map data to suppress vibrations. The attitude control controls attitude in response to steering and acceleration. Of course, these various types of control may be combined.

[0012] The required values ​​of the behavior parameters are 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. In other words, in this embodiment, the method of calculating the required values ​​of the behavior parameters 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 M ｐ , and heave force F ｈ Therefore, the required value of the behavior parameter can be converted into 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 into 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.

[0014]

[0015] Hereinafter, the value obtained by converting the required value of the behavior parameter into the center of gravity 3 mode will be referred to as the "required value of the center of gravity 3 mode." ｒ , pitch moment M ｐ , and 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.

[0016] In the behavior model of the vehicle 10 shown in FIG. 1 , the suspension 20RLA suspending the left rear wheel 14RL is configured as an active suspension including an actuator 26RL. The suspension 20RRA suspending the right rear wheel 14RR is also configured as an active suspension including an actuator 26RR. The suspension 20FRA suspending 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 fully active suspensions that can actively apply vertical control forces to the wheels 14FR, 14RR, and 14RL using the actuators 26FR, 26RR, and 26RL. On the other hand, the suspension 20FL suspending the front left wheel 14FL is a conventional suspension without an actuator, i.e., a non-active suspension.

[0017] 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 description, the wheels equipped with active suspensions are also referred to as "controlled wheels." In other words, 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.

[0018] 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 equation (2).

[0019]

[0020] As described above, the required values ​​of the behavior parameters can be converted into required values ​​for the three center-of-gravity modes, and therefore the required values ​​of the behavior parameters can be converted into control forces for each controlled wheel. Hereinafter, the control forces for each controlled wheel obtained by converting the required values ​​of the behavior parameters will also be referred to as "required control forces." Then, by controlling each of the actuators 26RL, 26RR, and 26FR so as to satisfy the required control forces, the required values ​​of the behavior parameters can be realized. In other words, a desired vehicle behavior can be realized with only three actuators 26RL, 26RR, and 26FR. Reducing the number of required actuators is preferable from the perspectives of improved mountability, cost reduction, weight reduction, power saving, and the like.

[0021] The above-described behavior control of the vehicle 10 can also be realized by "torque control" of the actuators 26RL, 26RR, and 26FR. However, torque control requires a force sensor, a torque sensor, and the like. Therefore, in this embodiment, in order to further reduce mounting space and costs, a method of realizing the above-described behavior control by "position control" of the actuators 26RL, 26RR, and 26FR is proposed. Below, a detailed description is given of a vehicle behavior control device that controls the behavior of the vehicle 10 by position control of the actuators 26RL, 26RR, and 26FR.

[0022] 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.

[0023] 2, vehicle 10 has a front axle 16F with steered left front wheels 14FL and right front wheels 14FR, and a rear axle 16R with non-steered left rear wheels 14RL and right rear wheels 14RR. However, the rear wheels 14RL and 14RR may also be provided with a steering mechanism. Vehicle 10 may be a front-wheel drive vehicle in which the front wheels 14FL and 14FR are driven, a rear-wheel drive vehicle in which the rear wheels 14RL and 14RR are driven, or an all-wheel drive vehicle in which the front wheels 14FL and 14FR and the rear wheels 14RL and 14RR are driven.

[0024] 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 an inactive suspension.

[0025] 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 the "first actuator 26RL") in addition to the spring 22RL and the shock absorber 24RL.

[0026] 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.

[0027] 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.

[0028] The controller 30 includes a processor 32 and a memory 34 coupled to the processor 32 .

[0029] The processor 32 executes various processes. The processor 32 may be configured, for example, by a central processing unit (CPU) including an arithmetic unit, registers, etc., a graphics processing unit (GPU), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), etc. The memory 34 stores various information necessary for the processor 32 to execute processes. The memory 34 may 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).

[0030] 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 on a computer-readable recording medium. Alternatively, the computer program 36 may be distributed over the air (OTA).

[0031] The controller 30 controls the actuators 26RL, 26RR, and 26FR based on signals acquired from the sensor group 40. In particular, the controller 30 executes processing to calculate position control amounts for the actuators 26RL, 26RR, and 26FR, and transmits the calculated position control amounts to the actuators 26RL, 26RR, and 26FR. In other words, the controller 30 controls the positions of the actuators 26RL, 26RR, and 26FR. The position control amount may provide a target position, or may provide 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.

[0032] Each of the actuators 26RL, 26RR, and 26FR operates in accordance with a position control amount received from the controller 30. Each of the actuators 26RL, 26RR, and 26FR is configured such that the control force applied to the corresponding controlled wheel changes depending on the controlled position.

[0033] Various configurations of such an actuator are possible. Fig. 3 is a diagram for explaining an example of the configuration of the actuator 26 according to the first embodiment. Fig. 3 shows an active suspension 20A including the actuator 26.

[0034] 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.

[0035] 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. In particular, in this embodiment, the controller 30 controls the position of the motor 28. Therefore, in this case, the position of the actuator 26 refers to the angle of the motor 28. The position control amount is the target angle or rotation angle amount of the motor 28.

[0036] When the motor 28 is rotated under the control of the controller 30, the torsion bar 27 is deformed, 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. The torsion bar 27 and the link mechanism 29 can also be said to be transmission members that transmit force between the motor 28 and the unsprung member 21 and the wheel 14.

[0037] 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.

[0038] For example, the actuator 26 may be composed of a coil spring having one end 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 considered 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.

[0039] For example, the actuator 26 may be composed of a motor supported on the sprung structure, a ball screw nut that rotates by the output of the motor, a ball screw shaft that moves axially by 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 considered as transmission members that transmit force between the motor, the unsprung member 21, and the wheel 14.

[0040] Incidentally, transmission members such as the torsion bar 27 can be considered to be elastic members having a predetermined 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.

[0041] FIG. 4 is a diagram showing the active suspension 20A modeled in terms of spring elements. In FIG. 4, Ks represents the stiffness of the spring 22, and Kb represents the stiffness of the torsion bar 27. Furthermore, z1 and z2 represent the unsprung and sprung displacements, respectively, with the upward direction in the drawing being the positive direction. In other words, 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.

[0042] 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 equation (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, that is, even if the relative displacement zΔ is zero, the actuator 26 generates a force F corresponding to the stroke amount (z2 - z1).

[0043]

[0044] 1.3 Behavior Control The following describes 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 first embodiment. Figure 5 is a flowchart showing an example of the processing executed by the controller 30 according to the first embodiment. The processing according to the flowchart shown in Figure 5 may be repeatedly executed at a predetermined processing cycle.

[0045] 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 the vertical control force for each wheel. That is, in step S110, the controller 30 calculates the vertical control force F for the left rear wheel RL.ｒli , the vertical control force F on the right rear wheel RE ｒri , the vertical control force F on the left front wheel FL fli , and the vertical control force F fri As described above, in this embodiment, the method for calculating the required values ​​of the behavior parameters is not particularly limited.

[0046] Next, in step S120, the controller 30 converts the required values ​​of the behavior parameters into required values ​​for the center of gravity 3 mode. The controller 30 converts the required values ​​of the behavior parameters into required roll moment M ｒ , required pitch moment M ｐ , and the required heave force F ｈ can be converted to

[0047] Next, in step S130, the controller 30 further converts the required value of the center of gravity 3 mode into the 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 "third required control force").

[0048] Next, in step S140, the controller 30 calculates the stroke amount of the first suspension 20RLA (first required stroke amount), the stroke amount of the second suspension 20RRA (second required stroke amount), and the stroke amount of the third suspension 20FRA (third required stroke amount) when the required values ​​of the behavior parameters are satisfied. Each required stroke amount can be thought of as the stroke amount that must be satisfied by each active suspension in behavior control of the vehicle 10.

[0049] Since the vertical control force for each wheel is proportional to the stroke amount of each suspension, the stroke amount of each suspension can be calculated by the following equation (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 the proportionality constants for the rear axle 16R and the front axle 16F, respectively. 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.

[0050]

[0051] 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.

[0052] 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 the required stroke amounts (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:

[0053] As explained 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 position control. Therefore, by using formula (3), the controller 30 can 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") can be calculated by substituting z2-z1 in the equation (3) for the first required stroke amount z ｓｒｌ Substituting the above, the first required control force F is ｒｌ By substituting the above, the first required relative displacement zΔ ｒｌ is expressed by the following equation (5).

[0054]

[0055] 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 ｒｒ The 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 associated with the third actuator 26FR (hereinafter also referred to as the "third required relative displacement") ｆｒ and can be calculated.

[0056] 4, the relative displacement zΔ is a quantity 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.

[0057] 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 through 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 performed to measure the coefficient A in the following equation (6). In this case, the relationship in the following equation (7) is established.

[0058]

[0059] 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 equation (8): In other words, the relative displacement zΔ can be converted into the angle of the motor 28 (position of the actuator 26) using equation (8).

[0060]

[0061] 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 part of the computer program 36.

[0062] In this way, based on the correspondence relationship 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.

[0063] In this way, 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 as to obtain the required control force for each controlled wheel.

[0064] Next, in step S160, the controller 30 controls the positions 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. ｒｌ , second required control force F ｒｒ , and the third required control force F ｆｒ The controller 30 can control the actuators 26RL, 26RR, and 26FR so as to satisfy the above equation. As a result, the required values ​​of the behavior parameters can be realized. After step S160, the controller 30 ends the current processing.

[0065] 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.

[0066] 1.4 Correction of Requirement Value 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. 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 equivalent to the reaction force of the transmission member corresponding 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 equivalent to the reaction force of the transmission member corresponding to the stroke amount.

[0067] On the other hand, in the vehicle behavior control system according to the first embodiment, the fourth suspension 20FL provided for the left front wheel 14FL does not include an actuator. In other words, 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 forces of the transmission members generated in the other suspensions. This may cause problems with the posture of the vehicle 10 during steering or acceleration / deceleration. This means that the suspension 20FL for the left front wheel 14FL is "softer" than the suspensions 20FR, 20RL, and 20RR for the other wheels 14FR, 14RL, and 14RR. In other words, an imbalance in suspension stiffness occurs between the left front wheel 14FL and the other wheels 14FR, 14RL, and 14RR. This imbalance in suspension stiffness can cause abnormal or uncomfortable vehicle body tilt during acceleration / deceleration or steering. Furthermore, an imbalance in suspension stiffness can cause a decrease in control performance, excessive oversteer or understeer, and the like.

[0068] For example, consider a case where the required relative displacement for each of the actuators 26RL, 26RR, and 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, resulting in a small stroke. Meanwhile, the fourth suspension 20FL does not generate a reaction force equivalent to the reaction force of the transmission member, resulting in a large stroke. As a result, the left front wheel 14FL may sink more than the other wheels, causing the vehicle 10 to assume a posture that appears to be tilted in the roll direction. Furthermore, when the vehicle 10 turns, for example, the left front wheel 14FL may sink more when turning right, while the right front wheel 14FR may not sink as much when turning left. This may result in a situation where the posture of the vehicle 10 varies depending on the direction of the turn.

[0069] 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 achieve a behavior of the vehicle 10 in which it can be assumed that the reaction force of the transmission member is also generated by the fourth suspension 20FL. The required value of the behavior parameter can be corrected based on a hypothetical reaction force value applied to the left front wheel 14FL by a transmission member assumed to be included in the fourth suspension 20FL.

[0070] Here, when the transmission member is the torsion bar 27, for example, the virtual reaction force value can be calculated as follows.

[0071] First, regarding acceleration and deceleration, the suspension share force F of the left front wheel 14FL excluding the suspension link reaction force is ｆｌｘ is calculated by the following formula (9).

[0072]

[0073] Here, each parameter is defined as follows: H: sprung center of gravity height 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 tanθ Ｉ : Side view suspension link inclination angle tanθ relative to the wheel center (point I) Ｊ : Suspension link inclination angle in side view relative to tire contact point (point J)

[0074] In the above equation (9), the driving force and regenerative force act at point I. The longitudinal G of the vehicle 10 may be estimated based on the required torque and force of the engine and drive motor, and the required force of the brakes and regeneration, or may be obtained by a sensor.

[0075] Next, regarding steering, the suspension share force F of the left front wheel 14FL excluding the suspension link reaction force is ｆｌｙis calculated by the following formula (10).

[0076]

[0077] Here, each parameter is defined as follows: β: vehicle slip angle V: vehicle speed r: yaw rate γ: front weight movement distribution ratio a ｙ :Horizontal GC ｐｆ : Front wheel cornering power tanθ ｙ : Rear view suspension link angle

[0078] 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.

[0079] The suspension force F of the left front wheel 14FL related to the acceleration and deceleration is ｆｌｘ and the suspension force F of the left front wheel 14FL related to steering. ｆｌｙ From this, the virtual reaction force value can be calculated by the following equation (11): ｂｆ is the assumed stiffness of the torsion bar 27 (including the bushing effect and link efficiency), K ｓｆ is the vertical stiffness of the suspension (excluding the 27% torsion bar).

[0080]

[0081] 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 equation (11) to the required value of the control force in the vertical direction for the left front wheel FL. In other words, in the corrected required value of the behavior parameter, the required value of the control force in the vertical direction for the left front wheel FL is calculated by F' in the following equation (12): ｒｌｉ In formula (12), F ｒｌｉ indicates the required value before correction.

[0082]

[0083] 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).

[0084] In step S111, the controller 30 calculates a hypothetical reaction force value that is applied to the left front wheel FL by the transmission member that is hypothesized 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 hypothetical reaction force value using the above equations (9) to (11).

[0085] 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).

[0086] 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.

[0087] 1.5 Effects As described above, according to the first embodiment, with regard to behavior control of the four-wheel vehicle 10, the three active suspensions 20RLA, 20RRA, and 20FRA can achieve controllability equivalent to that achieved when an active suspension is provided for each wheel. This allows for a reduction in the number of actuators required, thereby improving mountability, reducing costs, weight, and power consumption. 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 for the actuators 26RL, 26RR, and 26FR can be reduced. This in turn allows for further improvement in mountability and cost reduction.

[0088] 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, the suspension 20RRA provided on the right rear wheel 14RR could be an inactive suspension, and the suspensions 20RLA, 20FL, and 20FRA provided on the remaining wheels 14RL, 14FL, and 14FR could be active suspensions.

[0089] 2 Second Embodiment A vehicle behavior control device according to a second embodiment will be described below. In the following description, differences from the first embodiment will be mainly described, and content common to the first embodiment will be omitted as appropriate.

[0090] 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 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 F ｈ The required values ​​of the behavior parameters are directly the required values ​​of the center of gravity three modes.

[0091] 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.

[0092] 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 Mｒ , pitch moment M ｐ , and 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 As in the first embodiment, the method for calculating the required value of the behavior parameter is not particularly limited.

[0093] 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 in step S230 is the same as the process in step S130 described with reference to FIG.

[0094] Next, in step S240, the controller 30 calculates the first required stroke amount, the second required stroke amount, and the third required stroke amount when the required value of the behavior parameter is satisfied.

[0095] 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 for the center of gravity 3 mode. Therefore, the controller 30 first converts the required value for 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 for the center of gravity 3 mode will be referred to as the "converted required value". In formula (13), F ｒｌｚ is the required conversion value for the control force on the left rear wheel, F ｒｒｚ is the conversion requirement value for the control force on the right rear wheel, F ｆｌｚ is the conversion requirement value for the control force on the left front wheel, F ｆｒｚ is the conversion requirement value for the control force on the right front wheel.

[0096]

[0097] The controller 30 then calculates the first required stroke amount z ｓｒｌ , second required stroke amount z ｓｒｒ , and the third required stroke amount zｓｆｌ can be calculated.

[0098]

[0099] Next, in step S250, controller 30 calculates the position control amount for each of actuators 26RL, 26RR, 26FR that satisfies the required control force for each controlled wheel. The process in step S230 is the same as the process in step S150 described with reference to FIG.

[0100] Next, in step S260, the controller 30 controls the positions 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 achieves the required values ​​of the behavior parameters. After step S260, the controller 30 ends this processing.

[0101] 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.

[0102] 2.2 Correction of Required Values ​​In the second embodiment, as in the first embodiment, the required values ​​of the behavior parameters can be corrected by assuming that the fourth suspension 20FL includes a transmission member such as the torsion bar 27. As in the first embodiment, the required values ​​of the behavior parameters 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).

[0103] 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 ｈTherefore, in the second embodiment, a virtual reaction force value F is first calculated by the following equation (15): ｆｌｘｙ is converted into 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 transformation are called "transformed reaction force values." 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, F ｈｆｌｘｙ is the converted reaction force value related to the heave force.

[0104]

[0105] The required value of the behavior parameter is corrected by converting the converted reaction force obtained by the formula (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' in the following equation (16): 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.

[0106]

[0107] 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 the required roll moment M ｒ , required pitch moment M ｐ , and the required heave force F ｈAfter 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.

[0108] 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.

[0109] Although the embodiments have been described in detail above, these embodiments merely illustrate 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-described embodiments. The technology according to the present disclosure can be modified in various ways without departing from the spirit thereof, and these modifications are also included in the technical scope of the present disclosure.

[0110] 10 Vehicle, 30 Controller, 32 Processor, 34 Memory, 36 Computer program, 20RLA First suspension, 20RRA Second suspension, 20FRA Third suspension, 20FL Fourth suspension, 26RL First actuator, 26RR Second actuator, 26FR Third actuator, 27 Torsion bar

Claims

1. A vehicle behavior control device comprising: an ith suspension provided on an ith wheel (i = 1, 2, 3) of four wheels of a vehicle; a fourth suspension provided on a fourth wheel other than the ith wheel; and a controller, wherein the ith suspension includes an ith actuator whose position is controlled by the controller, and 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 the position control of the ith actuator in accordance with the ith position control amount.

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

3. A vehicle behavior control device as described in claim 1, wherein the controller is further configured to calculate an ith required stroke amount of the ith suspension when the required value of the behavior parameter is satisfied, and to calculate the ith position control amount based on the ith required stroke amount so as to obtain the ith required control force.

4. A vehicle behavior control device as claimed in claim 3, wherein the behavior parameter is a control force for each of the i-th wheel and the fourth wheel, and the controller is further configured to calculate 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.

5. A vehicle behavior control device as claimed in claim 3, wherein the behavior parameters are a roll moment, a pitch moment and a heave force acting on the centre of gravity of the vehicle, and the controller is further configured to convert the required values ​​relating to the roll moment, the pitch moment and the heave force into converted required values ​​relating to the control force for each of the i-th wheel and the fourth wheel, and to calculate the i-th required stroke amount of the i-th suspension which corresponds to the converted required value relating to the control force for the i-th wheel.

6. A vehicle behavior control device as claimed in any one of claims 1 to 5, wherein the i-th actuator includes a transmission member which transmits a reaction force generated by deformation as a control force, and the i-th actuator is configured to apply a vertical control force to the i-th wheel by deforming the transmission member.

7. A vehicle behavior control device according to claim 6, characterized in that the transmission member is a torsion bar.

8. A vehicle behavior control device as claimed in claim 6, wherein the fourth suspension does not include an actuator controlled by the controller, and the controller is further configured to: assume that the fourth suspension includes the transmission member, calculate a virtual reaction force value applied to the fourth wheel by the transmission member assumed to be included in the fourth suspension, and correct the required value based on the virtual reaction force value.

9. A vehicle behavior control device as claimed in claim 8, wherein the behavior parameter is a control force for each of the i-th wheel and the fourth wheel, and the controller is further configured to correct the required value relating to the control force for the fourth wheel by adding the virtual reaction force value to the required value.

10. A vehicle behavior control device as claimed in claim 8, wherein the behavior parameters are a roll moment, a pitch moment and a heave force acting on a center of gravity of the vehicle, and the controller is further configured to convert the virtual reaction force value into a converted reaction force value relating to the roll moment, the pitch moment and the heave force, and to correct the required values ​​relating to the roll moment, the pitch moment and the heave force by adding the converted reaction force value to the required values.

11. A vehicle behavior control method for controlling vehicle behavior using a computer, wherein the vehicle comprises: an ith suspension provided on an ith wheel (i = 1, 2, 3) of four wheels; and a fourth suspension provided on a fourth wheel other than the ith wheel, the ith suspension including an ith actuator whose position is controlled, the vehicle behavior control method comprising: obtaining a required value of a behavior parameter that determines the behavior of the vehicle; converting the required value of the behavior parameter into an ith required control force for the ith wheel; calculating an ith position control amount of the ith actuator based on the ith required control force; and performing the position control of the ith actuator in accordance with the ith position control amount.

12. A vehicle behavior control program that causes a computer to control the behavior of a vehicle, wherein the vehicle comprises: an ith suspension provided on an ith wheel (i = 1, 2, 3) of four wheels; and a fourth suspension provided on a fourth wheel other than the ith wheel, the ith suspension including an ith actuator whose position is controlled, the vehicle behavior control program causing the computer to execute the following processes: a process of acquiring a required value of a behavior parameter that determines the behavior of the vehicle; a process of converting the required value of the behavior parameter into an ith required control force for the ith wheel; a process of calculating an ith position control amount of the ith actuator based on the ith required control force; and a process of performing the position control of the ith actuator in accordance with the ith position control amount.

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