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

Abstract

To provide a vehicle behavior control device which can improve availability of control, regarding behavior control of a vehicle having active suspensions in all of fours wheels of the vehicle.SOLUTION: A vehicle behavior control device includes: first to fourth suspensions provided on each of first to fourth wheels of a vehicle; and a controller for controlling behavior of the vehicle. The first to fourth suspensions include first to fourth actuators for applying control force in a vertical direction to the first to fourth wheels. When a failure of the fourth actuator other than an i-th actuator (i=1 to 3) out of the first to fourth actuators occurs, the controller calculates a request value of a behavior parameter indicating the behavior of the vehicle, converts the request value of the behavior parameter into i-th request control force to the i-th actuator, controls the i-th actuator on the basis of the i-th request control force and thereby controls the behavior of the vehicle.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] In recent years, a technology has been devised in which all four wheels of a vehicle are equipped with active suspensions, and each actuator independently applies a vertical control force to each wheel to control the vehicle's behavior. For example, Patent Document 1 discloses a suspension control device that drives and controls the actuators provided on each wheel according to a predetermined control law, and controls the heave, roll, and pitch of the vehicle so as to improve both ride comfort and road contact.

[0003] In addition, the following Patent Document 2 is a document that shows the technical level of this technical field. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-073239 A [Patent Document 2] JP 2010-179692 A Summary of the Invention [Problem to be solved by the invention]

[0005] In a conventional vehicle behavior control system having active suspensions on all four wheels, if a failure occurs in any one of the four actuators, the control force from the failed actuator cannot be obtained appropriately, and the desired vehicle behavior cannot be achieved. For this reason, when a failure occurs in an actuator, the control is usually stopped. From the viewpoint of control availability, it is undesirable to stop the control due to the occurrence of a failure in one actuator, even though the remaining three actuators are operating normally.

[0006] One object of the present disclosure, in consideration of the above-mentioned problems, is to provide a technology that can improve the availability of control regarding the behavior control of a vehicle equipped with active suspension on all four wheels of the vehicle. [Means for solving the problem]

[0007] A first aspect of the present disclosure relates to a vehicle behavior control device.

[0008] A vehicle behavior control device according to a first aspect includes first to fourth suspensions provided on first to fourth wheels of a vehicle, respectively, and a controller that controls the behavior of the vehicle. The first to fourth suspensions include first to fourth actuators that apply vertical control forces to the first to fourth wheels, respectively. When a failure occurs in a fourth actuator other than an ith actuator (i=1 to 3) among the first to fourth actuators, the controller calculates a required value of a behavior parameter that represents the behavior of the vehicle, converts the required value of the behavior parameter into an ith required control force for the ith actuator, and controls the ith actuator based on the ith required control force, thereby controlling the behavior of the vehicle.

[0009] A second aspect of the present disclosure relates to a vehicle behavior control method for controlling the behavior of a vehicle, wherein the vehicle includes first to fourth suspensions provided for first to fourth wheels, respectively, and the first to fourth suspensions include first to fourth actuators that apply vertical control forces to the first to fourth wheels, respectively.

[0010] A vehicle behavior control method according to a second aspect includes, when a failure occurs in an actuator other than an ith actuator (i=1 to 3) among the first to fourth actuators, calculating a required value of a behavior parameter representing the behavior of both actuators, converting the required value of the behavior parameter into an ith required control force for the ith actuator, and controlling the ith actuator based on the ith required control force.

[0011] A third aspect of the present disclosure relates to a vehicle behavior control program for causing a computer to control the behavior of a vehicle. Here, the vehicle includes first to fourth suspensions provided on first to fourth wheels, respectively. The first to fourth suspensions include first to fourth actuators that apply vertical control forces to the first to fourth wheels, respectively.

[0012] A vehicle behavior control program according to a third aspect causes a computer to execute, when a failure occurs in an actuator other than an ith actuator (i=1 to 3) among the first to fourth actuators, a process of calculating a required value of a behavior parameter representing the behavior of both actuators, a process of converting the required value of the behavior parameter into an ith required control force for the ith actuator, and a process of controlling the ith actuator based on the ith required control force. Effect of the Invention

[0013] According to the present disclosure, even if one of the four actuators fails, the vehicle behavior control can be continued while ensuring controllability with the remaining three actuators, thereby improving the availability of control. [Brief description of the drawings]

[0014] [Figure 1] 1 is a conceptual diagram showing a configuration example of a vehicle behavior control device; [Diagram 2] FIG. 2 is a conceptual diagram for explaining vehicle behavior control by three actuators. [Diagram 3] 5 is a flowchart showing a process executed by a controller according to the embodiment. [Figure 4] 4 is a flowchart showing a process executed by a controller according to the embodiment in vehicle behavior control using three actuators. [Diagram 5] FIG. 2 is a diagram for explaining an example of a configuration of an actuator. [Figure 6] FIG. 1 is a diagram showing a model of a suspension. [Figure 7]FIG. 13 is a conceptual diagram for explaining a situation when a failure occurs in one actuator. [Figure 8] 6 is a flowchart showing a process executed by a controller according to the embodiment regarding calculation of a behavior parameter request. [Figure 9] 6 is a flowchart showing a process executed by a controller according to the embodiment regarding calculation of a behavior parameter request. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] 1. Example of vehicle behavior control device configuration 1 is a schematic diagram showing an example of the configuration of a vehicle behavior control device that controls the behavior of a vehicle 10 according to this embodiment. The vehicle 10 has a front left wheel 14FL and a front right wheel 14FR on a front axle 16F, and a rear left wheel 14RL and a rear right wheel 14RR on a rear axle 16R. The vehicle behavior control device includes suspensions 20FL, 20FR, 20RL, and 20RR, a controller 30, and a sensor group 40.

[0016] The suspension 20FL is provided for the left front wheel 14FL and suspends the left front wheel 14FL from the vehicle body 12. The suspension 20FL includes an actuator 26FL in addition to a spring 22FL and a shock absorber 24FL. The actuator 26FL is configured to actively apply a control force in the vertical direction to the left front wheel 14FL. In other words, the suspension 20FL is a fully active suspension.

[0017] The suspension 20FR is provided for the right front wheel 14FR and suspends the right front wheel 14FR from the vehicle body 12. The suspension 20FR includes an actuator 26FR in addition to a spring 22FR and a shock absorber 24FR. The actuator 26FR is configured to be able to actively apply a control force in the vertical direction to the right front wheel 14FR. In other words, the suspension 20FR is a fully active suspension.

[0018] The suspension 20RL is provided for the left rear wheel 14RL and suspends the left rear wheel 14RL from the vehicle body 12. The suspension 20RL includes an actuator 26RL in addition to a spring 22RL and a shock absorber 24RL. The actuator 26RL is configured to actively apply a control force in the vertical direction to the left rear wheel 14RL. In other words, the suspension 20RL is a fully active suspension.

[0019] The suspension 20RR is provided for the right rear wheel 14RR and suspends the right rear wheel 14RR from the vehicle body 12. The suspension 20RR includes an actuator 26RR in addition to a spring 22RR and a shock absorber 24RR. The actuator 26RR is configured to actively apply a control force in the vertical direction to the right rear wheel 14RR. In other words, the suspension 20RR is a fully active suspension.

[0020] There is no particular limitation on the configuration or mechanism of the actuator 26. An example of the configuration of the actuator 26 will be described in Section 3 below.

[0021] 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 the actuators 26FL, 26FR, 26RL, and 26RR via the in-vehicle network.

[0022] The controller 30 includes a processor 32 and a memory 34 coupled to the processor 32. The processor 32 executes various processes. The memory 34 stores a computer program 36 executable by the processor 32 and various information related thereto. The computer program 36 may be recorded on a computer-readable recording medium. The functions of the controller 30 are realized by cooperation between the processor 32, which executes the computer program 36, and the memory 34.

[0023] The controller 30 executes "vehicle behavior control" that controls the behavior of the vehicle 10. Examples of vehicle behavior control include sprung feedback control, unsprung feedback control, attitude control, preview control, and the like. The sprung feedback control suppresses vibration of the sprung member based on a sprung state quantity calculated using the measurement values ​​of a sprung acceleration sensor. The unsprung feedback control suppresses vibration of the unsprung member based on an unsprung state quantity calculated using the measurement values ​​of the sprung acceleration sensor and the vehicle height sensor. The attitude control controls the attitude in response to steering and acceleration / deceleration. The preview control predicts road surface conditions using a database of camera images and high-precision map data, and suppresses vibration. These various types of control may be combined.

[0024] The controller 30 executes vehicle behavior control by controlling the actuators 26FL, 26FR, 26RL, and 26RR of the suspensions 20FL, 20FR, 20RL, and 20RR based on signals obtained by the sensor group 40. In the vehicle behavior control, a required control force in the vertical direction is calculated for each of the four wheels of the vehicle 10 according to the purpose. The controller 30 can realize a desired behavior of the vehicle 10 by controlling each actuator 26 so that the vertical control force applied to each wheel 14 becomes the calculated required control force.

[0025] Incidentally, in the vehicle behavior control device, each of the four actuators 26FL, 26FR, 26RL, and 26RR may become uncontrollable due to a failure. If a failure occurs in any one of the actuators 26, the control force of the failed actuator 26 cannot be obtained appropriately. As a result, the desired behavior of the vehicle 10 cannot be realized by normal control that attempts to achieve the required control force of each wheel 14 by controlling the four actuators 26FL, 26FR, 26RL, and 26RR. On the other hand, even if any one of the actuators 26 fails, there may be cases where the remaining three actuators 26 can be normally controlled.

[0026] Therefore, when a failure occurs in any one of the actuators 26, the controller 30 according to this embodiment executes vehicle behavior control using the remaining three actuators 26. As will be described below, with only three actuators 26, it is possible to achieve controllability equivalent to that of normal vehicle behavior control using four actuators 26. Below, the vehicle behavior control using the three actuators 26 will be described in more detail.

[0027] 2 3 Actuator Control As described above, when a failure occurs in any one of the actuators 26, the controller 30 according to this embodiment executes vehicle behavior control using the remaining three actuators 26 (hereinafter, also simply referred to as "three-actuator control"). In the following, the three-actuator control will be described, taking as an example a case in which a failure occurs in the actuator 26FL of the left front wheel 14FL in particular.

[0028] FIG. 2 shows a behavior model for explaining the three-actuator control. The behavior of the vehicle 10 is represented by behavior parameters. In the behavior model shown in FIG. 2, the behavior parameters are the motion mode at the sprung center of gravity position of the vehicle 10, that is, the roll moment M r , pitch moment M p , and the heave force F hThe roll moment M r , pitch moment M p , and the heave force F h The motion modes consisting of these are called the three center of gravity modes.

[0029] In three-actuator control, the required control force in the vertical direction is also calculated for each of the four wheels of the vehicle 10 according to the purpose of vehicle behavior control. Hereinafter, the required control force calculated for each of the four wheels of the vehicle 10 is specifically referred to as the "base required control force." In three-actuator control, the controller 30 first converts the base required control force for the four wheels into required values ​​for the center-of-gravity three modes (behavior parameters). Now, the base required control force for the left front wheel 14FL is calculated as F fli , the base required control force for the right front wheel 14FR is F fri , the base required control force for the left rear wheel 14RL is F rli , the base required control force for the right rear wheel 14RR is F rri At this time, the controller 30 calculates the base required control force F fli ,F fri ,F rli ,F rri is converted into the required values ​​for the three center of gravity modes according to the following formula (1).

[0030]

number

[0031] In formula (1), l f , l r , T f , and T r are the distance between the front axle 16F and the center of gravity, the distance between the rear axle 16R and the center of gravity, the front tread, and the rear tread, respectively (see FIG. 2). These parameters are given in advance as specification information of the vehicle 10. The controller 30 uses the specification information of the vehicle 10 and the base required control forces F fli ,F fri ,F rli ,F rri Based on this, the required values ​​for the three modes of center of gravity (Fh ,M r ,M p The required values ​​for the three center-of-gravity modes may include roll moment, pitch moment, and heave force required for attitude control associated with steering, acceleration, and deceleration.

[0032] Required value F for center of gravity 3 modes h ,M r ,M p After the calculation, the controller 30 calculates the required value F of the three center-of-gravity modes according to the following formula (2): h ,M r ,M p The required control forces F fr ,F rr ,F rl Convert to.

[0033]

number

[0034] The controller 30 calculates the vertical control force applied to the right front wheel 14FR based on the required control force F fr Similarly, the controller 30 controls the actuator 26FR so that the vertical control force applied to the right rear wheel 14RR is equal to the required control force F rr Similarly, the controller 30 controls the actuator 26RR so that the vertical control force applied to the left rear wheel 14RL is equal to the required control force F rl The actuator 26RL is controlled so as to satisfy the above.

[0035] In this way, in the three-actuator control, the required values ​​of the three center-of-gravity modes are distributed to the three actuators 26FR, 26RR, and 26RL, thereby realizing the desired behavior including all of roll, pitch, and heave in the vehicle 10. In other words, the desired vehicle behavior can be realized with only the three actuators 26FR, 26RR, and 26RL.

[0036] The control method of the actuators 26 may be position control (angle control) instead of force control (torque control). In the case of position control (angle control), the controller 30 calculates the required control forces F fr ,F rr ,F rl The controller 30 then calculates required position control amounts for the three actuators 26FR, 26RR, and 26RL so as to obtain the above-mentioned position control amount. Then, the controller 30 controls the positions of the actuators 26FR, 26RR, and 26RL in accordance with the required position control amount.

[0037] In the above description, a case where a failure occurs in the actuator 26FL of the left front wheel 14FL is taken as an example. However, as can be understood from the above description, similar three-actuator control is possible even if a failure occurs in the actuator 26 of another wheel 14.

[0038] In general terms, the above is as follows. The first to fourth wheels 14-1 to 14-4 are provided with first to fourth suspensions 20-1 to 20-4, which are active suspensions. The first to fourth suspensions 20-1 to 20-4 include a first to fourth actuators 26-1 to 26-4 that apply vertical control forces to the first to fourth wheels 14-1 to 14-4, respectively. Now, assume that a failure has occurred in the fourth actuator 26-4 other than the i-th actuator 26-i (i=1 to 3) among the first to fourth actuators 26-1 to 26-4. In this case, the controller 30 executes three-actuator control using the i-th actuator 26-i.

[0039] In the three-actuator control, the controller 30 calculates a required value of a behavior parameter representing the behavior of the vehicle 10 (see formula (1)). Next, the controller 30 converts the required value of the behavior parameter into an ith required control force Fi for the ith actuator 26-i (see formula (2)). The controller 30 then controls the behavior of the vehicle 10 by controlling the ith actuator 26-i based on the ith required control force Fi. This makes it possible to achieve controllability equivalent to that of normal vehicle behavior control using four actuators 26 with only three actuators 26. Furthermore, even if a failure occurs in any one of the actuators 26, the vehicle behavior control can be continued while ensuring controllability, thereby improving the availability of the control.

[0040] Fig. 3 is a flowchart showing an example of processing executed by the controller 30 according to this embodiment. The processing according to the flowchart shown in Fig. 3 may be repeatedly executed at a predetermined processing cycle while the vehicle behavior control device is running.

[0041] In step S110, the controller 30 checks the failure state of the four actuators 26FL, 26FR, 26RL, and 26RR. For example, the controller 30 obtains information on the failure state of each of the four actuators 26FL, 26FR, 26RL, and 26RR via a diagnostic system provided in the vehicle 10. At this time, the controller 30 may obtain information on the type of failure in addition to the presence or absence of a failure.

[0042] If a failure has not occurred in any of the four actuators 26FL, 26FR, 26RL, and 26RR (step S120; No), the controller 30 executes normal vehicle behavior control using the four actuators 26FL, 26FR, 26RL, and 26RR (step S160).

[0043] If a failure has occurred in the four actuators 26FL, 26FR, 26RL, and 26RR (step S120; Yes), the controller 30 judges whether or not three-actuator control is possible (step S130). A case where three-actuator control is possible means that a failure has occurred in one actuator 26 among the four actuators 26FL, 26FR, 26RL, and 26RR. In other words, it can be said that three actuators 26 among the four actuators 26FL, 26FR, 26RL, and 26RR can be normally controlled. For example, the controller 30 judges whether or not three-actuator control is possible based on the information acquired in step S110.

[0044] If the three-actuator control is possible (step S130; Yes), the controller 30 executes the three-actuator control (step S140). On the other hand, if the three-actuator control is not possible (step S130; No), the controller 30 stops the vehicle behavior control (step S150).

[0045] Fig. 4 is a flowchart showing an example of processing for three-actuator control executed by the controller 30. Fig. 4 shows a generalized case in which it is assumed that a failure has occurred in the fourth actuator 26-4 other than the ith actuator 26-i (i = 1 to 3) among the first actuators 26-1 to the fourth actuators 26-4, and three-actuator control is executed by the ith actuator 26-i (i = 1 to 3).

[0046] In step S200, the controller 30 calculates a required value of a behavior parameter that represents the behavior of the vehicle 10 (see equation (1)).

[0047] Next, in step S300, the controller 30 converts the required value of the behavior parameter into the i-th required control force Fi for the i-th actuator 26-i (see equation (2)).

[0048] Then, in step S400, the controller 30 performs vehicle behavior control by controlling the i-th actuator 26-i based on the i-th required control force Fi.

[0049] The functions of the vehicle behavior control device according to this embodiment are realized by the processing executed by the controller 30 in this manner. The vehicle behavior control method according to this embodiment is also implemented by the processing executed by the controller 30 in this manner. The vehicle behavior control program according to this embodiment is also implemented by the computer program 36 that causes the controller 30 to execute the processing in this manner.

[0050] 3 Actuator configuration examples FIG. 5 is a diagram for explaining an example of the configuration of the actuator 26. In the example shown in FIG. 5, the actuator 26 includes a motor 28 supported by the sprung structure and a torsion bar 27 having one end connected to an output shaft of the motor 28. The other end of the torsion bar 27 is connected to the unsprung member 21 (e.g., a suspension arm) via a link mechanism 29. The operation of the motor 28 is controlled by a controller 30. When the motor 28 rotates, 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.

[0051] 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 force between the motor 28 and the unsprung member 21 and between the wheels 14 and the motor 28.

[0052] Fig. 6 is a model of the suspension 20 in the case of the actuator 26 shown in Fig. 5. The spring 22 and the torsion bar 27 function as a parallel spring provided between the sprung and unsprung masses. Ks is the stiffness of the spring 22, and Kb is the stiffness of the torsion bar 27. As the reaction force generated in the torsion bar 27 increases, the suspension 20 becomes stiffer.

[0053] 4. Offset reaction force caused by actuator failure Continuing to consider the actuator 26 illustrated in Figures 5 and 6. The types of failures that occur in this actuator 26 are roughly divided into the following two types. (1) Fixed failure: The operating position (motor angle) is fixed due to a motor sticking or a control failure. (2) Shut-off failure: Shut-off of force transmission due to damage to the link mechanism 29 or breakage of the torsion bar 27, or Shut-off of the output of the actuator 26 due to loss of power, etc.

[0054] 7 is a conceptual diagram for considering a situation in which a failure occurs in one of the actuators 26. As an example, it is assumed that a failure occurs in the actuator 26FL of the left front wheel 14FL. For simplicity, it is also assumed that the control command values ​​for all the actuators 26 are zero. Then, consider a case in which an external force is input to the torsion bar 27 from the unsprung member 21 side due to at least one of the acceleration / deceleration and steering of the vehicle 10.

[0055] 4.1 Force control (torque control) It is assumed that the force commands for all actuators 26 are zero. In normal actuators 26FR, 26RL, 26RR, an external force from the unsprung member 21 side is input to the motor 28 via the torsion bar 27. Since the force command is zero and the motor 28 does not output force, the motor 28 also rotates in response to the rotation of the torsion bar 27. Therefore, the reaction force (torsion moment) generated in the torsion bar 27 is zero or extremely small. On the other hand, the actuator 26FL of the left front wheel 14FL where a failure has occurred is as follows.

[0056] First, consider the case where the failure of the actuator 26FL is a "fixed failure". In this case, even if an external force from the unsprung member 21 side is input to the motor 28, the motor 28 does not rotate. Therefore, the torsion bar 27 is twisted in response to the external force input from the unsprung member 21 side. In other words, a reaction force (torsion moment) in response to the external force input from the unsprung member 21 side is generated in the torsion bar 27. This means that the suspension 20FL of the left front wheel 14FL where the fixed failure has occurred is "harder" than the suspensions 20FR, 20RL, and 20RR of the other wheels 14FR, 14RL, and 14RR. In other words, an imbalance in suspension stiffness occurs between the left front wheel 14FL where the fixed failure has occurred 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. Furthermore, an imbalance in suspension stiffness can cause a decrease in control performance, excessive oversteer or understeer, and the like.

[0057] Next, consider the case where the failure of the actuator 26FL is a "disconnection failure." When force transmission is interrupted due to damage to the link mechanism 29 or breakage of the torsion bar 27, this is equivalent to the case where the stiffness Kb (see FIG. 6) of the torsion bar 27 is zero. Therefore, no reaction force is generated in the torsion bar 27 even if an external force is input. When the output of the motor 28 is interrupted, this is equivalent to the force command being zero. In either case, the stiffness of the suspension 20FL of the left front wheel 14FL where a disconnection failure has occurred is equivalent to the suspensions 20FR, 20RL, and 20RR of the other wheels 14FR, 14RL, and 14RR. No imbalance occurs as in the case of the fixed failure described above.

[0058] 4.2 Position control (angle control) It is assumed that the position commands for all the actuators 26 are zero. In the normal actuators 26FR, 26RL, 26RR, an external force from the unsprung member 21 side is input to the motor 28 via the torsion bar 27. Since the position command is zero and the position of the motor 28 does not change, the torsion bar 27 is twisted in response to the external force input from the unsprung member 21 side. In other words, a reaction force (torsion moment) in response to the external force input from the unsprung member 21 side is generated in the torsion bar 27. On the other hand, the actuator 26FL of the left front wheel 14FL in which a failure has occurred is as follows.

[0059] First, consider the case where the failure of the actuator 26FL is a "shut-off failure." When the force transmission is shut off due to damage to the link mechanism 29 or breakage of the torsion bar 27, it is equivalent to the case where the stiffness Kb (see FIG. 6) of the torsion bar 27 is zero. Therefore, even if an external force is input, no reaction force is generated in the torsion bar 27. When the output of the motor 28 is shut off, the motor 28 does not output a force, so the motor 28 also rotates in response to the rotation of the torsion bar 27. Therefore, the reaction force generated in the torsion bar 27 is zero or extremely small. This means that the suspension 20FL of the left front wheel 14FL where the shut-off failure has occurred is "softer" than the suspensions 20FR, 20RL, and 20RR of the other wheels 14FR, 14RL, and 14RR. In other words, an imbalance in suspension stiffness occurs between the left front wheel 14FL where the shut-off failure has occurred and the other wheels 14FR, 14RL, and 14RR. Such an imbalance in suspension stiffness can cause abnormal or uncomfortable leaning of the vehicle body during acceleration / deceleration or steering, as well as a decrease in control performance, excessive oversteer or understeer, etc.

[0060] Next, consider the case where the failure of the actuator 26FL is a "fixed failure." In this case, even if an external force is input to the motor 28 from the unsprung member 21 side, the motor 28 does not rotate. This is equivalent to the position command being zero. Therefore, the hardness of the suspension 20FL of the left front wheel 14FL where the fixed failure has occurred is equivalent to the suspensions 20FR, 20RL, and 20RR of the other wheels 14FR, 14RL, and 14RR. No imbalance occurs as in the case of the above-mentioned cut-off failure.

[0061] 4.3 Offset reaction force As described above, when the actuator 26FL using the torsion bar 27 fails, there is a possibility that an imbalance in suspension stiffness occurs between the left front wheel 14FL and the other wheels 14FR, 14RL, and 14RR. In the above description, for simplicity, the control command values ​​for all the actuators 26 are set to zero, but even if some vehicle behavior control is performed by the controller 30, the imbalance in suspension stiffness continues to exist. Such an imbalance in suspension stiffness causes abnormality or discomfort in the inclination of the vehicle body during acceleration / deceleration or steering. In addition, the imbalance in suspension stiffness causes a decrease in control performance, excessive oversteer or understeer, etc. Therefore, when a failure occurs in the actuator 26FL, it is desirable to appropriately perform the above-mentioned three-actuator control taking into account the imbalance in suspension stiffness.

[0062] Therefore, an "offset reaction force" is introduced as a parameter indicating the degree of imbalance in suspension stiffness caused by the occurrence of a failure. The offset reaction force is the "difference" of the reaction force between when a failure occurs and when it does not occur. More specifically, the offset reaction force is the difference between when a failure occurs and when it does not occur of the reaction force generated in the torsion bar 27 of the actuator 26FL due to an external force input from the unsprung member 21 side. In other words, the offset reaction force is the "difference" between when a failure occurs and when it does not occur of the reaction force generated in the torsion bar 27 of the actuator 26FL due to at least one of the acceleration / deceleration and steering of the vehicle 10. The larger the offset reaction force, the larger the "difference" between when a failure occurs and when it does not occur.

[0063] As shown in FIG. 7, the offset reaction force depends on whether the control method of actuator 26 is force control or position control. The offset reaction force also depends on whether the type of failure of actuator 26FL is fixed fail or shutoff fail. When the control method is force control and the failure type is fixed fail, an offset reaction force corresponding to the input external force is generated. When the control method is force control and the failure type is shutoff fail, the offset reaction force is zero. When the control method is position control and the failure type is shutoff fail, an offset reaction force corresponding to the input external force is generated. When the control method is position control and the failure type is fixed fail, the offset reaction force is zero.

[0064] According to this embodiment, when a failure occurs in actuator 26FL, the above-mentioned three-actuator control is performed taking into account the offset reaction force. Hereinafter, the three-actuator control taking into account the offset reaction force will be described in detail.

[0065] 5. Three-actuator control considering offset reaction force The controller 30 according to this embodiment is configured to calculate the required value of the behavior parameter taking into consideration the offset reaction force in the three-actuator control. The following describes the calculation of the required value of the behavior parameter taking into consideration the offset reaction force in each of the cases of force control (torque control) and position control (angle control) of each actuator 26. Note that in the following description, a failure occurs in the fourth actuator 26-4 other than the ith actuator 26-i (i = 1 to 3) among the first actuator 26-1 to the fourth actuator 26-4, and three-actuator control is performed by the ith actuator 26-i (i = 1 to 3).

[0066] 5.1 Force control (torque control) As shown in FIG. 7, when the failure of the fourth actuator 26-4 is a fixed failure, an imbalance in suspension stiffness occurs. More specifically, the fourth suspension 20-4 becomes stiffer than the other suspensions 20 by the amount of the offset reaction force. In other words, an extra torsion bar reaction force is generated in the fourth actuator 26-4 by the amount of the offset reaction force. Therefore, the controller 30 calculates the required value of the behavior parameter so that the offset reaction force generated by the fixed failure is canceled. Specifically, the controller 30 executes the process as follows.

[0067] First, the controller 30 corrects the fourth base required control force by subtracting the offset reaction force from the fourth base required control force calculated for the fourth wheel 14-4. 4b , offset reaction force F xy Then, the corrected fourth base required control force F' 4b is expressed by the following equation (3): The controller 30 then calculates the i-th base required control force calculated for the i-th wheel 14-i and the corrected fourth base required control force F' 4b The required value of the behavior parameter is calculated based on (see formula (1)).

number

[0068] Here, the offset reaction force F xy is a reaction force generated in the torsion bar of the fourth actuator 26-4 due to acceleration / deceleration and steering. Therefore, the offset reaction force F xy can be calculated as follows:

[0069] First, regarding the acceleration / deceleration input, the suspension share force F of the fourth wheel 14-4 excluding the suspension link reaction force is x is calculated using the following formula (4).

number

[0070] 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)

[0071] In the above formula (4), 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 the regenerative force. Alternatively, it may be obtained by a sensor.

[0072] Next, regarding the steering input, the suspension share force F of the fourth wheel 14-4 excluding the suspension link reaction force is y is calculated using the following formula (5).

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[0073] 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

[0074] 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.

[0075] The suspension force F of the fourth wheel 14-4 with respect to the acceleration / deceleration input is x and the suspension force F of the fourth wheel 14-4 with respect to the steering input. y and the offset reaction force F xy can be calculated by the following formula (6): bf is the assumed torsion bar stiffness (including bushing effect and link efficiency), K sf is the vertical stiffness of the suspension (excluding the torsion bar).

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[0076] In this way, when performing force control (torque control) on each actuator 26, the controller 30 can calculate the required value of the behavior parameter taking into account the offset reaction force. This makes it possible to eliminate the deviation caused by the offset reaction force in three-actuator control. In the case of a shutoff failure, the offset reaction force is zero. Therefore, in this case, the controller 30 only needs to calculate the required value of the behavior parameter in the same way as in the case of normal control.

[0077] Fig. 8 is a flowchart showing the process executed by the controller 30 for calculating the required value of the behavior parameter taking into account the offset reaction force. The process according to the flowchart shown in Fig. 8 is executed when calculating the required value of the behavior parameter in the three-actuator control (step S200 in Fig. 4).

[0078] In step S211, the controller 30 calculates an ith base required control force for the ith wheel 14-i (i=1 to 3) and a fourth base required control force for the fourth wheel 14-4.

[0079] Next, in step S212, the controller 30 checks the type of failure of the fourth actuator 26-4. For example, the controller 30 checks the type of failure of the fourth actuator 26-4 via a diagnostic system provided in the vehicle 10.

[0080] If the failure of the fourth actuator 26-4 is not a fixed failure (step S213; No), the process proceeds to step S216. In step S216, the controller 30 calculates a required value of the behavior parameter based on the ith base required control force and the fourth base required control force, without correcting the fourth base required control force.

[0081] If the failure of the fourth actuator 26-4 is a fixed failure (step S213; Yes), the controller 30 calculates the generated offset reaction force (step S214, see equations (4) to (6)).

[0082] After step S214, in step S215, the controller 30 corrects the fourth base required control force by subtracting the offset reaction force from the fourth base required control force calculated in step S211 (see equation (3)).

[0083] After step S215, in step S216, the controller 30 calculates a required value of the behavior parameter based on the i-th base required control force and the corrected fourth base required control force.

[0084] 5.2 Position control (angle control) As shown in FIG. 7, when the failure of the fourth actuator 26-4 is a blocking failure, an imbalance in suspension stiffness occurs. More specifically, the fourth suspension 20-4 becomes softer than the other suspensions 20 by the amount of the offset reaction force. That is, in the fourth actuator 26-4, the torsion bar reaction force is insufficient by the amount of the offset reaction force. Therefore, the controller 30 calculates the required value of the behavior parameter so that the offset reaction force generated by the fixed failure is compensated for. Specifically, the controller 30 executes the process as follows.

[0085] First, the controller 30 corrects the fourth base required control force by adding the offset reaction force to the fourth base required control force calculated for the fourth wheel 14-4. That is, the corrected fourth base required control force F' 4b is expressed by the following equation (7): The controller 30 then calculates the i-th base required control force calculated for the i-th wheel 14-i and the corrected fourth base required control force F' 4b The required value of the behavior parameter is calculated based on (see formula (1)).

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[0086] Here, the offset reaction force F xy can be calculated using equations (4) to (6) in the same way as in the case of force control (torque control).

[0087] In this way, when performing position control (angle control) on each actuator 26, the controller 30 can calculate the required value of the behavior parameter taking into account the offset reaction force. This makes it possible to eliminate deviations due to the offset reaction force in three-actuator control. In the case of a fixed failure, the offset reaction force is zero. Therefore, in this case, the controller 30 only needs to calculate the required value of the behavior parameter in the same way as in the case of normal control.

[0088] Fig. 9 is a flowchart showing the process executed by the controller 30 for calculating the required value of the behavior parameter taking into account the offset reaction force. The process according to the flowchart shown in Fig. 9 is executed when calculating the required value of the behavior parameter in the three-actuator control (step S200 in Fig. 4).

[0089] The processes in steps S221 and S222 are equivalent to the processes in steps S211 and S212 in FIG.

[0090] If the failure of the fourth actuator 26-4 is not a shutoff failure (step S223; No), the process proceeds to step S226. In step S226, the controller 30 calculates the required value of the behavior parameter based on the ith base required control force and the fourth base required control force without correcting the fourth base required control force.

[0091] If the failure of the fourth actuator 26-4 is a shutoff failure (step S223; Yes), the controller 30 calculates the generated offset reaction force (step S224, see equations (4) to (6)).

[0092] After step S224, in step S225, the controller 30 corrects the fourth base required control force by adding the offset reaction force to the fourth base required control force calculated in step S221 (see equation (7)).

[0093] After step S225, in step S226, the controller 30 calculates a required value of the behavior parameter based on the i-th base required control force and the corrected fourth base required control force. [Explanation of symbols]

[0094] 10 Vehicle, 14 Wheel, 20 Suspension, 26 Actuator, 30 controllers, 32 processors, 34 memory, 36 Computer Programs

Claims

1. first to fourth suspensions provided on first to fourth wheels of the vehicle, respectively; A controller for controlling a behavior of the vehicle; Equipped with the first to fourth suspensions each include a first to fourth actuator that apply a vertical control force to the first to fourth wheels, When a failure occurs in a fourth actuator other than an ith actuator (i=1 to 3) among the first to fourth actuators, the controller Calculating a required value of a behavior parameter representing a behavior of the vehicle; converting the required value of the behavior parameter into an i-th required control force for the i-th actuator; The behavior of the vehicle is controlled by controlling the i-th actuator based on the i-th required control force. It was configured as Vehicle behavior control device.

2. The vehicle behavior control device according to claim 1, the first to fourth actuators each include a first to fourth transmission member configured to transmit a reaction force generated by deformation to the first to fourth wheels, the first to fourth actuators are configured to apply the vertical control forces to the first to fourth wheels by deforming the first to fourth transmission members, respectively; the offset reaction force is a difference between a reaction force generated in the fourth transmission member due to at least one of acceleration / deceleration and steering of the vehicle, between a state in which the failure has occurred and a state in which the failure has not occurred, The controller is configured to calculate the required value of the behavior parameter taking into account the offset reaction force. Vehicle behavior control device.

3. The vehicle behavior control device according to claim 2, Each of the first to fourth transmission members includes a torsion bar. Vehicle behavior control device.

4. The vehicle behavior control device according to claim 2 or 3, The offset reaction force depends on the type of the failure of the fourth actuator. Vehicle behavior control device.

5. The vehicle behavior control device according to claim 4, the controller is configured to force-control each of the first to fourth actuators; When the failure of the fourth actuator is a fixed operating position, the controller calculates the required value of the behavior parameter so that the offset reaction force is canceled. It is configured as follows: Vehicle behavior control device.

6. The vehicle behavior control device according to claim 5, The controller further comprises: calculating an i-th base required control force for the i-th wheel and a fourth base required control force for the fourth wheel; correcting the fourth base required control force by subtracting the offset reaction force from the fourth base required control force; The required value of the behavior parameter is calculated based on the i-th base required control force and the corrected fourth base required control force. It is configured as follows: Vehicle behavior control device.

7. The vehicle behavior control device according to claim 4, the controller is configured to force-control each of the first to fourth actuators; When the failure of the fourth actuator is a cutoff of force transmission via the fourth transmission member or a cutoff of the output of the fourth actuator, the offset reaction force is zero. Vehicle behavior control device.

8. The vehicle behavior control device according to claim 4, the controller is configured to control the positions of the first to fourth actuators, When the failure of the fourth actuator is interruption of force transmission via the fourth transmission member or interruption of the output of the fourth actuator, the controller calculates the required value of the behavior parameter so that the offset reaction force is compensated for. It is configured as follows: Vehicle behavior control device.

9. The vehicle behavior control device according to claim 8, The controller further comprises: calculating an i-th base required control force for the i-th wheel and a fourth base required control force for the fourth wheel; correcting the fourth base required control force by adding the offset reaction force to the fourth base required control force; The required value of the behavior parameter is calculated based on the i-th base required control force and the corrected fourth base required control force. It is configured as follows: Vehicle behavior control device.

10. The vehicle behavior control device according to claim 4, the controller is configured to control the positions of the first to fourth actuators, When the fourth actuator fails in a fixed operating position, the offset reaction force is zero. Vehicle behavior control device.

11. A vehicle behavior control method for controlling a vehicle behavior, comprising: the vehicle includes first to fourth suspensions provided on the first to fourth wheels, respectively; the first to fourth suspensions each include a first to fourth actuator that apply a vertical control force to the first to fourth wheels, When it is detected that a fourth actuator other than an i-th actuator (i=1 to 3) among the first to fourth actuators has failed, the vehicle behavior control method includes: Calculating a required value of a behavior parameter representing a behavior of the vehicle; converting the required value of the behavior parameter into an i-th required control force for the i-th actuator; controlling the i-th actuator based on the i-th required control force to control the behavior of the vehicle; Includes A vehicle behavior control method.

12. A vehicle behavior control program for causing a computer to control a vehicle behavior, the vehicle includes first to fourth suspensions provided on the first to fourth wheels, respectively; the first to fourth suspensions each include a first to fourth actuator that apply a vertical control force to the first to fourth wheels, When it is detected that a fourth actuator other than an i-th actuator (i=1 to 3) among the first to fourth actuators has failed, the vehicle behavior control program A process of calculating a required value of a behavior parameter representing 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 actuator; a process of controlling a behavior of the vehicle by controlling the i-th actuator based on the i-th required control force; causing the computer to execute Vehicle behavior control program.

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