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

Abstract

Provided is a vehicle behavior control device capable of improving the usability of control with respect to behavior control of a vehicle provided with active suspensions on all four wheels of the vehicle. This vehicle behavior control device is provided with: first to fourth suspensions provided to first to fourth wheels of a vehicle, respectively; and a controller that controls the behavior of the vehicle. Each of the first to fourth suspensions includes first to fourth actuators that apply a control force in the vertical direction to the first to fourth wheels. When a failure has occurred in a fourth actuator other than an i-th actuator (i = 1-3) among the first to fourth actuators, the controller calculates a request value for a behavior parameter indicating behavior of the vehicle, converts the request value for the behavior parameter to an i-th request control force for the i-th actuator, and controls the i-th request control force based on the i-th request control force. The behavior of the vehicle is controlled by controlling the i-th actuator on the basis of the i-th request control force.

Description

Technical Field

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

[0002] In recent years, a technology has been considered in which all four wheels of a vehicle are equipped with active suspensions and the behavior of the vehicle is controlled by using each actuator to independently apply a control force in the up-and-down direction to each wheel. For example, Patent Document 1 discloses a suspension control device that drives and controls the actuators equipped on each wheel according to a predetermined control rule and controls the heave, roll, and pitch of the vehicle in a manner that takes into account both the improvement of ride comfort and the improvement of ground contact.

[0003] In addition, there is the following Patent Document 2 as a document indicating the technical level in this technical field.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2009-073239

[0005] Patent Document 2: Japanese Patent Application Publication No. 2010-179692

[0006] In the conventional vehicle behavior control in which all four wheels of the vehicle are equipped with active suspension, when any one of the four actuators fails, the control force generated by the failed actuator cannot be properly obtained, and the desired vehicle behavior cannot be achieved. Therefore, when the actuator fails, the control is usually stopped. It is not preferable from the viewpoint of control availability to stop the control due to the failure of one actuator even though the remaining three actuators operate normally. Summary of the invention

[0007] The present disclosure has been made in view of the above-mentioned problems, and one object of the present disclosure is to provide a technology capable of improving the usability of control regarding the behavior control of a vehicle having active suspensions on all four wheels of the vehicle.

[0008] A first aspect of the present disclosure relates to a vehicle behavior control device.

[0009] The vehicle behavior control device involved in the first viewpoint comprises: a first suspension to a fourth suspension, which are respectively arranged on the first wheel to the fourth wheel of the vehicle; and a controller, which controls the behavior of the vehicle. The first suspension to the fourth suspension respectively include a first actuator to a fourth actuator that apply control forces in the up-down direction to the first wheel to the fourth wheel. In the event that a fourth actuator other than the i-th actuator (i=1 to 3) among the first actuator to the fourth actuator fails, the controller calculates the required value of the behavior parameter representing the behavior of the vehicle, and converts the required value of the behavior parameter into the i-th required control force for the i-th actuator, and controls the behavior of the vehicle by controlling the i-th actuator based on the i-th required control force.

[0010] The second aspect of the present disclosure relates to a vehicle behavior control method for controlling the behavior of a vehicle. Here, the vehicle includes a first suspension to a fourth suspension respectively provided on a first wheel to a fourth wheel. In addition, the first suspension to the fourth suspension respectively include a first actuator to a fourth actuator for applying a control force in an up-down direction to the first wheel to the fourth wheel.

[0011] The vehicle behavior control method involved in the second viewpoint includes the following steps: when a failure occurs in the 4th actuator other than the i-th actuator (i=1~3) among the 1st to 4th actuators, calculating the required value of the behavior parameter representing the behavior of the vehicle; converting the required value of the behavior parameter into the i-th required control force for the i-th actuator; and controlling the i-th actuator based on the i-th required control force.

[0012] The third aspect of the present disclosure relates to a vehicle behavior control program that causes a computer to execute control of the behavior of a vehicle. Here, the vehicle includes a first suspension to a fourth suspension that are respectively provided on a first wheel to a fourth wheel. In addition, the first suspension to the fourth suspension respectively include a first actuator to a fourth actuator that applies a control force in an up-down direction to the first wheel to the fourth wheel.

[0013] The vehicle behavior control program involved in the third viewpoint enables the computer to perform the following processing: when a failure occurs in the 4th actuator other than the ith actuator (i=1~3) among the 1st to 4th actuators, the processing of calculating the required value of the behavior parameter representing the behavior of the vehicle; the processing of converting the required value of the behavior parameter into the ith required control force for the ith actuator; and the processing of controlling the ith actuator based on the ith required control force.

[0014] According to the present disclosure, even if one of the four actuators fails, the remaining three actuators can ensure controllability and continue vehicle behavior control, thereby improving control availability. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram showing a configuration example of a vehicle behavior control device.

[0016] Figure 2 This is a schematic diagram for explaining vehicle behavior control by three actuators.

[0017] Figure 3 This is a flowchart showing the processing executed by the controller involved in the embodiment.

[0018] Figure 4 This is a flowchart showing the processing executed by the controller according to the embodiment in vehicle behavior control performed by three actuators.

[0019] Figure 5 This is a diagram for explaining an example of the configuration of an actuator.

[0020] Figure 6 This is a diagram that models the suspension.

[0021] Figure 7 This is a schematic diagram for explaining a situation when one actuator fails.

[0022] Figure 8 This is a flowchart showing a process performed by a controller according to an embodiment for calculating a behavior parameter requirement.

[0023] Fig. 9 This is a flowchart showing a process performed by a controller according to an embodiment for calculating a behavior parameter requirement. DETAILED DESCRIPTION

[0024] 1 Example of the configuration of a vehicle behavior control device

[0025] Figure 1 1 is a schematic diagram showing a configuration example of a vehicle behavior control device for controlling the behavior of a vehicle 10 according to the present embodiment. The vehicle 10 includes a left front wheel 14FL and a right front wheel 14FR at a front axle 16F, and a left rear wheel 14RL and a right rear wheel 14RR at a rear axle 16R. The vehicle behavior control device includes suspensions 20FL, 20FR, 20RL, 20RR, a controller 30, and a sensor group 40.

[0026] 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 the spring 22FL and the shock absorber 24FL. The actuator 26FL is configured to actively apply a control force in the up-and-down direction to the left front wheel 14FL. That is, the suspension 20FL is a fully active suspension.

[0027] 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 the spring 22FR and the shock absorber 24FR. The actuator 26FR is configured to actively apply a control force in the up-and-down direction to the right front wheel 14FR. That is, the suspension 20FR is a fully active suspension.

[0028] 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 the spring 22RL and the shock absorber 24RL. The actuator 26RL is configured to actively apply a control force in the up-and-down direction to the left rear wheel 14RL. That is, the suspension 20RL is a fully active suspension.

[0029] 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 the spring 22RR and the shock absorber 24RR. The actuator 26RR is configured to actively apply a control force in the up-and-down direction to the right rear wheel 14RR. That is, the suspension 20RR is a fully active suspension.

[0030] The structure and mechanism of the actuator 26 are not particularly limited. An example of the structure of the actuator 26 will be described in the following section 3.

[0031] The controller 30 is connected to the sensor group 40 via an in-vehicle network such as CAN (Controller Area Network). The controller 30 obtains signals from the sensor group 40. The sensor group 40 includes, for example, an acceleration sensor, a vehicle height sensor, a wheel speed sensor, and other sensors that measure physical quantities related to the behavior of the vehicle 10. In addition, the controller 30 is also connected to the actuators 26FL, 26FR, 26RL, and 26RR via the in-vehicle network.

[0032] The controller 30 includes a processor 32 and a memory 34 coupled to the processor 32. The processor 32 performs 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 also be recorded in a computer-readable recording medium. The functions of the controller 30 are realized by the cooperation between the processor 32 executing the computer program 36 and the memory 34.

[0033] The controller 30 performs "vehicle behavior control" to control the behavior of the vehicle 10. Examples of vehicle behavior control include sprung feedback control, unsprung feedback control, posture control, and preview control. The sprung feedback control suppresses the vibration of the sprung components based on the sprung state quantity calculated using the measurement value of the sprung acceleration sensor. The unsprung feedback control suppresses the vibration of the unsprung components based on the unsprung state quantity calculated using the measurement values ​​of the sprung acceleration sensor and the vehicle height sensor. Posture control controls the posture for steering manipulation and acceleration and deceleration. The preview control uses a database of camera images and high-precision map data to anticipate road conditions and suppress vibrations. The above-mentioned various controls can be combined.

[0034] The controller 30 performs vehicle behavior control by controlling the actuators 26FL, 26FR, 26RL, and 26RR of the suspensions 20FL, 20FR, 20RL, and 20RR based on the signals obtained from the sensor group 40. In the vehicle behavior control, the required control force in the up-down direction is calculated for each of the four wheels of the vehicle 10 according to the purpose. The controller 30 controls each actuator 26 so that the control force in the up-down direction applied to each wheel 14 becomes the calculated required control force, thereby realizing the desired behavior of the vehicle 10.

[0035] It should be noted that in the vehicle behavior control device, each of the four actuators 26FL, 26FR, 26RL, and 26RR may fail to be controlled. If any one of the actuators 26 fails, the control force generated by the failed actuator 26 cannot be properly obtained. Furthermore, in the normal control that attempts to control the four actuators 26FL, 26FR, 26RL, and 26RR to achieve the required control force of each wheel 14, the desired behavior of the vehicle 10 cannot be achieved. On the other hand, it is conceivable that even if any one of the actuators 26 fails, the remaining three actuators 26 can still be controlled normally.

[0036] In view of this, when any one of the actuators 26 fails, the controller 30 according to the present embodiment executes the vehicle behavior control performed by the remaining three actuators 26. As described below, controllability equivalent to the normal vehicle behavior control performed by four actuators 26 can be achieved by only three actuators 26. The vehicle behavior control performed by the three actuators 26 will be described in more detail below.

[0037] 2 3 Actuator control

[0038] As described above, when any one of the actuators 26 fails, the controller 30 according to the present embodiment executes vehicle behavior control (hereinafter also referred to as "3-actuator control") by the remaining three actuators 26. The 3-actuator control will be described below, taking as an example a case where the actuator 26FL of the left front wheel 14FL fails.

[0039] Figure 2 1 shows a behavior model for explaining the three-actuator control. The behavior of the vehicle 10 is represented by a behavior parameter. Figure 2 In the behavior model shown, the behavior parameters include the motion pattern at the sprung center of gravity of the vehicle 10, that is, the rolling moment M r , pitch moment M p and the fluctuation force F h . In the following, the roll moment M r , pitch moment Mp and the fluctuation force F h The movement pattern formed is called the center of gravity 3 pattern.

[0040] In the 3-actuator control, the required control force in the up-down direction is also calculated for each of the four wheels of the vehicle 10 according to the purpose of the vehicle behavior control. Hereinafter, the required control force calculated for each of the four wheels of the vehicle 10 is particularly referred to as the "basic required control force". In the 3-actuator control, the controller 30 first converts the basic required control force for the four wheels into the required value of the center of gravity 3 mode (behavior parameter). At this time, the basic required control force for the left front wheel 14FL is set to F fli , the basic required control force for the right front wheel 14FR is set to F fri , the basic required control force for the left rear wheel 14RL is set to F rli , the basic required control force for the right rear wheel 14RR is set to F rri At this time, the controller 30 converts the basic required control force F for the four wheels into fli 、F fri 、F rli 、F rri Converted to the required value of the center of gravity 3 mode.

[0041] [Formula 1]

[0042]

[0043] In formula (1), l f , l r , T f and T r They 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 track and the rear track (refer to Figure 2 ). These parameters are given in advance as specification information of the vehicle 10. The controller 30 controls the vehicle 10 based on the specification information of the vehicle 10 and the basic required control force F for the four wheels. fli 、F fri 、F rli 、F rri To calculate the required value of the 3rd mode of the center of gravity (F h 、M r 、M p ). The required value of the center of gravity 3 mode may include the roll moment, pitch moment, and heave force required for posture control accompanying steering, acceleration and deceleration.

[0044] After calculating the required value F of the center of gravity 3 mode h 、M r 、M pThen, the controller 30 converts the required value F of the center of gravity mode 3 into h 、M r 、M p Converted into the required control force F for the three actuators 26FR, 26RR, and 26RL fr 、F rr 、F rl .

[0045] [Formula 2]

[0046]

[0047] Then, the controller 30 sets the vertical control force applied to the right front wheel 14FR to the required control force F fr Similarly, the controller 30 controls the actuator 26FR in such a manner that the vertical control force applied to the right rear wheel 14RR becomes the required control force F rr Similarly, the controller 30 controls the actuator 26RR in such a manner that the vertical control force applied to the left rear wheel 14RL becomes the required control force F rl The actuator 26RL is controlled in this manner.

[0048] In this way, in the three-actuator control, by distributing the required values ​​of the three center of gravity patterns to the three actuators 26FR, 26RR, and 26RL, all desired behaviors including roll, pitch, and heave are realized in the vehicle 10. That is, the desired vehicle behavior can be realized only by the three actuators 26FR, 26RR, and 26RL.

[0049] The control method of the actuator 26 may also be position control (angle control) instead of force control (torque control). In the case of position control (angle control), the controller 30 obtains the required control force F for the three actuators 26FR, 26RR, and 26RL represented by the above equation (2): fr 、F rr 、F rl The controller 30 calculates the required position control amounts for the three actuators 26FR, 26RR, and 26RL in the manner of . Then, the controller 30 performs position control of the actuators 26FR, 26RR, and 26RL based on the required position control amounts.

[0050] In the above description, the case where the actuator 26FL of the left front wheel 14FL fails is taken as an example. However, as understood from the above description, even if the actuator 26 of the other wheels 14 fails, the same three-actuator control can be achieved.

[0051] If generalized, it is as follows. Each of the first wheel 14-1 to the fourth wheel 14-4 is provided with a first suspension 20-1 to a fourth suspension 20-4 as an active suspension. The first suspension 20-1 to the fourth suspension 20-4 respectively include a first actuator 26-1 to a fourth actuator 26-4 for applying control forces in the up-down direction to the first wheel 14-1 to the fourth wheel 14-4. Now, it is assumed that the fourth actuator 26-4 other than the i-th actuator 26-i (i=1 to 3) among the first actuator 26-1 to the fourth actuator 26-4 fails. At this time, the controller 30 performs a three-actuator control performed by the i-th actuator 26-i.

[0052] In the three-actuator control, the controller 30 calculates the required value of the behavior parameter representing the behavior of the vehicle 10 (refer to formula (1)). Then, 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 (refer to formula (2)). Moreover, the controller 30 controls the behavior of the vehicle 10 by controlling the i-th actuator 26-i based on the i-th required control force Fi. As a result, controllability equivalent to the usual vehicle behavior control performed by four actuators 26 can be achieved by only three actuators 26. Furthermore, since controllability can be ensured and vehicle behavior control can be continued even if any actuator 26 fails, the availability of control is improved.

[0053] Figure 3 1 is a flowchart showing an example of the processing executed by the controller 30 according to the present embodiment. During the activation of the vehicle behavior control device, the processing may be repeatedly executed in accordance with a predetermined processing cycle. Figure 3 The processing involved in the flowchart shown.

[0054] In step S110, the controller 30 confirms the fault status of the four actuators 26FL, 26FR, 26RL, and 26RR. For example, the controller 30 obtains information on the fault status of each of the four actuators 26FL, 26FR, 26RL, and 26RR via a diagnostic system equipped in the vehicle 10. At this time, the controller 30 can obtain not only the presence or absence of a fault but also information related to the type of the fault.

[0055] When none of the four actuators 26FL, 26FR, 26RL, and 26RR fails (step S120; No), the controller 30 executes normal vehicle behavior control by the four actuators 26FL, 26FR, 26RL, and 26RR (step S160).

[0056] When a failure occurs in the four actuators 26FL, 26FR, 26RL, and 26RR (step S120; Yes), the controller 30 determines whether the three-actuator control can be performed (step S130). The three-actuator control can be performed when one of the four actuators 26FL, 26FR, 26RL, and 26RR fails. Alternatively, it can be said that three of the four actuators 26FL, 26FR, 26RL, and 26RR can be normally controlled. For example, the controller 30 determines whether the three-actuator control can be performed based on the information obtained in step S110.

[0057] 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).

[0058] Figure 4 This is a flowchart showing an example of a process executed by the controller 30 regarding the three-actuator control. Figure 4 This shows a case where, generally speaking, a failure occurs 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, and three-actuator control is performed by the i-th actuator 26-i (i=1 to 3).

[0059] In step S200 , the controller 30 calculates a required value of a behavior parameter indicating the behavior of the vehicle 10 (see equation (1)).

[0060] Next, in step S300 , the controller 30 converts the required value of the behavior parameter into an i-th required control force Fi for the i-th actuator 26 - i (see equation (2)).

[0061] Then, in step S400 , the controller 30 controls the vehicle behavior by controlling the i-th actuator 26 - i based on the i-th required control force Fi.

[0062] By executing the processing in this way by the controller 30, the functions of the vehicle behavior control device involved in the present embodiment can be realized. In addition, by executing the processing in this way by the controller 30, the vehicle behavior control method involved in the present embodiment can be implemented. In addition, by the computer program 36 that causes the controller 30 to execute the processing in this way, the vehicle behavior control program involved in the present embodiment can be realized.

[0063] 3Actuator Configuration Example

[0064] Figure 52 is a diagram for explaining an example of the structure of the actuator 26. Figure 5 In the example shown, the actuator 26 includes a motor 28 supported by a 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 (e.g., 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.

[0065] In addition, when the vehicle 10 is accelerated or decelerated, or when steering is performed, external force input from the unsprung member 21 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.

[0066] Figure 6 Yes Figure 5 The figure is a modeled diagram of the suspension 20 in the case of the actuator 26 shown. The spring 22 and the torsion bar 27 function as a parallel spring provided between the sprung part and the unsprung part. Ks is the rigidity of the spring 22, and Kb is the rigidity of the torsion bar 27. As the reaction force generated in the torsion bar 27 increases, the suspension 20 becomes harder.

[0067] 4. Offset reaction force caused by actuator failure

[0068] Next, Figure 5 as well as Figure 6 The actuator 26 shown in FIG. 1 is considered as an example. The types of failures that occur in the actuator 26 are roughly divided into the following two types.

[0069] (1) Fixed fault: Fixed operating position (motor angle) due to motor sticking, control failure, etc.

[0070] (2) Cut-off failure: Cut-off of force transmission due to damage to the link mechanism 29, breakage of the torsion bar 27, etc., or cut-off of the output of the actuator 26 due to power loss, etc.

[0071] Figure 7This is a schematic diagram for studying the situation when one actuator 26 fails. As an example, it is assumed that the actuator 26FL of the left front wheel 14FL fails. In addition, for the sake of simplicity, it is assumed that the control command values ​​for all actuators 26 are zero. In addition, the situation where an external force is input from the unsprung member 21 side to the torsion bar 27 due to at least one of the acceleration and deceleration of the vehicle 10 and the steering operation is considered.

[0072] 4.1 Force control (torque control)

[0073] Assume that the force command for all the actuators 26 is zero. In normal actuators 26FR, 26RL, 26RR, the 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, the motor 28 does not output a force, so the motor 28 also rotates according 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 that has failed is described as follows.

[0074] First, consider the case where the failure of the actuator 26FL is a "fixed failure". In this case, even if the 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 according to the external force input from the unsprung member 21 side. That is, a reaction force (torsion moment) corresponding to the external force input from the unsprung member 21 side occurs in the torsion bar 27. This means that the suspension 20FL of the left front wheel 14FL that has a fixed failure becomes "harder" than the suspensions 20FR, 20RL, 20RR of the other wheels 14FR, 14RL, 14RR. That is, an imbalance in suspension hardness occurs between the left front wheel 14FL that has a fixed failure and the other wheels 14FR, 14RL, 14RR. Such an imbalance in suspension hardness causes abnormal tilting of the vehicle body during acceleration, deceleration, and steering, and a sense of discomfort. In addition, the imbalance in suspension hardness causes a reduction in control performance, excessive oversteering or understeering, and the like.

[0075] Next, let us consider the case where the failure of the actuator 26FL is a "cut-off failure". When the force transmission is cut off due to damage to the link mechanism 29, breakage of the torsion bar 27, etc., the rigidity Kb (see Figure 6 ) 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 cut off, it is equivalent to the case where the force command is zero. In any case, the hardness of the suspension 20FL of the left front wheel 14FL that has a cut-off failure is the same as the suspension 20FR, 20RL, 20RR of the other wheels 14FR, 14RL, 14RR. Unbalance such as the above-mentioned fixed failure does not occur.

[0076] 4.2 Position control (angle control)

[0077] Assume that the position command for all the actuators 26 is zero. In the normal actuators 26FR, 26RL, and 26RR, the 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, the position of the motor 28 does not change, so the torsion bar 27 is twisted according to the external force input from the unsprung member 21 side. That is, a reaction force (torsion moment) corresponding 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 that has failed is described as follows.

[0078] First, let us consider the case where the failure of the actuator 26FL is a "cut-off failure". When the force transmission is cut off due to damage to the link mechanism 29, breakage of the torsion bar 27, etc., the rigidity Kb (see Figure 6 ) 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 cut off, since the motor 28 does not output force, the motor 28 also rotates according 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 that has a cut-off failure becomes "softer" than the suspensions 20FR, 20RL, 20RR of the other wheels 14FR, 14RL, 14RR. That is, an imbalance in suspension hardness occurs between the left front wheel 14FL that has a cut-off failure and the other wheels 14FR, 14RL, 14RR. Such an imbalance in suspension hardness causes abnormal tilting of the vehicle body during acceleration, deceleration, and steering operations, and a sense of disharmony. In addition, the imbalance in suspension hardness causes a reduction in control performance, excessive oversteering or understeering, and the like.

[0079] Next, let's 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. This is equivalent to the position command being zero. Therefore, the hardness of the suspension 20FL of the left front wheel 14FL that has a fixed failure is the same as the suspension 20FR, 20RL, 20RR of the other wheels 14FR, 14RL, 14RR. The imbalance as in the case of the above-mentioned cut-off failure does not occur.

[0080] 4.3 Deviation reaction force

[0081] As described above, in the event that the actuator 26FL utilizing the torsion bar 27 fails, an imbalance in suspension hardness may occur between the left front wheel 14FL and the other wheels 14FR, 14RL, and 14RR. In the above description, for simplicity, it is assumed that the control command values ​​for all actuators 26 are zero, but even in the case of certain vehicle behavior control by the controller 30, the imbalance in suspension hardness continues to exist. Such an imbalance in suspension hardness causes abnormal tilting of the vehicle body during acceleration, deceleration, and steering operations, and a sense of incoordination. In addition, the imbalance in suspension hardness causes a reduction in control performance, excessive oversteering or understeering, and the like. Therefore, in the event that the actuator 26FL fails, it is desirable to appropriately implement the above-mentioned 3-actuator control in consideration of the imbalance in suspension hardness.

[0082] In view of this, the "deviation reaction force" is introduced as a parameter indicating the degree of imbalance in suspension stiffness caused by the occurrence of a fault. The deviation reaction force is the "difference" of the reaction force between when a fault occurs and when a fault does not occur. In more detail, the deviation reaction force is the difference between when a fault occurs and when a fault does not occur in the reaction force generated in the torsion bar 27 of the actuator 26FL due to the external force input from the unsprung member 21 side. That is, the deviation reaction force is the "difference" between when a fault occurs and when a fault does not occur in the reaction force generated in the torsion bar 27 of the actuator 26FL due to at least one of the acceleration / deceleration and steering operation of the vehicle 10. The larger the deviation reaction force, the larger the "difference" between when a fault occurs and when a fault does not occur.

[0083] like Figure 7 As shown, the deviation reaction force depends on whether the control method of the actuator 26 is force control or position control. In addition, the deviation reaction force depends on whether the type of the fault of the actuator 26FL is a fixed fault or a cut-off fault. When the control method is force control and the fault type is a fixed fault, a deviation reaction force corresponding to the input external force is generated. When the control method is force control and the fault type is a cut-off fault, the deviation reaction force is zero. When the control method is position control and the fault type is a cut-off fault, a deviation reaction force corresponding to the input external force is generated. When the control method is position control and the fault type is a fixed fault, the deviation reaction force is zero.

[0084] According to the present embodiment, when a failure of the actuator 26FL occurs, the above-mentioned three-actuator control is performed in consideration of the deviation reaction force. The three-actuator control in consideration of the deviation reaction force will be described in detail below.

[0085] 5. 3-actuator control taking into account the reaction force of deviation

[0086] The controller 30 involved in this embodiment is configured to calculate the required value of the behavior parameter in consideration of the deviation reaction force in the three-actuator control. The following describes the calculation of the required value of the behavior parameter in consideration of the deviation reaction force for each of the cases where force control (torque control) and position control (angle control) are performed on each actuator 26. In the following description, if the fourth actuator 26-4 other than the i-th actuator 26-i (i=1 to 3) among the first actuator 26-1 to the fourth actuator 26-4 fails, the three-actuator control performed by the i-th actuator 26-i (i=1 to 3) is performed.

[0087] 5.1 Force control (torque control)

[0088] like Figure 7 As shown, 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 is stiffer than the other suspensions 20 by an amount corresponding to the deviation reaction force. That is, in the fourth actuator 26-4, an excess torsion bar reaction force is generated according to the amount of the deviation reaction force. Therefore, the controller 30 calculates the required value of the behavior parameter in such a way that the deviation reaction force generated by the fixed failure is eliminated. Specifically, the controller 30 performs processing as follows.

[0089] First, the controller 30 corrects the fourth basic required control force by subtracting the deviation reaction force from the fourth basic required control force calculated for the fourth wheel 14 - 4 . 4b , set the deviation reaction force to F xy , then the modified fourth basis requires control force F' 4b It is expressed as the following equation (3). Then, the controller 30 calculates the i-th basic required control force for the i-th wheel 14 - i and the fourth basic required control force F′ after correction. 4b To calculate the required value of the behavior parameter (refer to formula (1)).

[0090] [Formula 3]

[0091] F′ 4b =F 4b -F xy …(3)

[0092] Here, the deviation reaction force F xy The deviation reaction force F is the reaction force generated by the torsion bar of the fourth actuator 26-4 due to acceleration, deceleration, and steering. xy It can be calculated as follows.

[0093] First, regarding the acceleration / deceleration input, the suspension share force F of the fourth wheel 14 - 4 after the suspension link reaction force is removed is calculated by the following equation (4): x .

[0094] [Formula 4]

[0095]

[0096] Here, each parameter is defined as follows.

[0097] H: Height of the center of gravity on the sprung

[0098] l: Wheelbase

[0099] m: sprung mass

[0100] a xp : Front and rear G acceleration side

[0101] a xm : Front and rear G deceleration side

[0102] α xp : Front driving force distribution

[0103] α xm : Front brake force distribution

[0104] α k : Front regeneration ratio

[0105] tanθ I : Side view suspension link inclination angle for the wheel center (point I)

[0106] tanθ J : Side view suspension link inclination angle for the tire contact point (J point)

[0107] In the above formula (4), it is assumed that the driving force and the regenerative force act at point I. In addition, the front and rear G of the vehicle 10 can be estimated based on the required torque and force of the engine and the driving motor and the required force of braking and regeneration. Alternatively, it can be obtained by a sensor.

[0108] Next, regarding the steering input, the suspension share force F of the fourth wheel 14 - 4 excluding the suspension link reaction force is calculated by the following equation (5): y .

[0109] [Formula 5]

[0110]

[0111] Here, each parameter is defined as follows.

[0112] β: body slip angle

[0113] V: Vehicle speed

[0114] r: yaw rate

[0115] γ: forward weighted mobile allocation ratio

[0116] a y : Horizontal G

[0117] C pf : Cornering force of the front wheel

[0118] tanθ y : Suspension link inclination angle from the back

[0119] The lateral G of the vehicle 10 can be estimated based on the steering angle, vehicle speed, etc. Alternatively, it can be acquired by a sensor.

[0120] The suspension share force F of the fourth wheel 14 - 4 related to the above-mentioned acceleration and deceleration input can be x and the suspension share force F of the fourth wheel 14-4 related to the steering input y The deviation reaction force F is calculated by the following formula (6): xy Here, K bf is the assumed torsion bar stiffness (including bushing effect and connecting rod efficiency), K sf It is the vertical rigidity of the suspension (excluding the torsion bar).

[0121] [Formula 6]

[0122]

[0123] In this way, when force control (torque control) is performed on each actuator 26, the controller 30 can calculate the required value of the behavior parameter in consideration of the deviation reaction force. As a result, in the three-actuator control, the deviation accompanying the deviation reaction force can be eliminated. However, in the case of a cut-off fault, the deviation 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.

[0124] Figure 8 1 is a flowchart showing the processing executed by the controller 30 regarding the calculation of the required value of the behavior parameter taking into account the deviation reaction force. When the required value of the behavior parameter is calculated in the three-actuator control ( Figure 4 Step S200) is performed Figure 8 The processing involved in the flowchart shown.

[0125] In step S211 , the controller 30 calculates an i-th basic required control force for the i-th wheel 14 - i (i=1 to 3) and a fourth basic required control force for the fourth wheel 14 - 4 .

[0126] 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 using a diagnostic system provided in the vehicle 10 .

[0127] 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 the required value of the behavior parameter based on the i-th base required control force and the fourth base required control force without correcting the fourth base required control force.

[0128] When the failure of the fourth actuator 26 - 4 is a fixed failure (step S213 ; Yes), the controller 30 calculates the generated deviation reaction force (step S214 , refer to equations (4) to (6)).

[0129] After step S214 , in step S215 , the controller 30 corrects the fourth base required control force by subtracting the deviation reaction force from the fourth base required control force calculated in step S211 (see equation (3)).

[0130] After step S215 , in step S216 , the controller 30 calculates a required value of a behavior parameter based on the i-th base required control force and the corrected fourth base required control force.

[0131] 5.2 Position control (angle control)

[0132] like Figure 7 As shown, when the failure of the fourth actuator 26-4 is a cut-off failure, an imbalance in the suspension hardness occurs. More specifically, the fourth suspension 20-4 becomes softer than the other suspensions 20 by an amount corresponding to the deviation reaction force. That is, in the fourth actuator 26-4, the torsion bar reaction force lacks an amount corresponding to the deviation reaction force. Therefore, the controller 30 calculates the required value of the behavior parameter in a manner to compensate for the deviation reaction force generated by the fixed failure. Specifically, the controller 30 performs processing as follows.

[0133] First, the controller 30 corrects the fourth basic required control force by adding the deviation reaction force to the fourth basic required control force calculated for the fourth wheel 14 - 4 . That is, the corrected fourth basic required control force F′ 4b It is expressed by the following equation (7). Then, the controller 30 calculates the i-th basic required control force for the i-th wheel 14 - i and the fourth basic required control force F′ after correction. 4b To calculate the required value of the behavior parameter (refer to formula (1)).

[0134] [Formula 7]

[0135] F′ 4b =F 4b +F xy …(7)

[0136] Here, the deviation reaction force Fxy can be calculated using equations (4) to (6) in the same manner as in the case of force control (torque control).

[0137] In this way, when position control (angle control) is performed on each actuator 26, the controller 30 can calculate the required value of the behavior parameter in consideration of the deviation reaction force. As a result, in the three-actuator control, the deviation accompanying the deviation reaction force can be eliminated. However, in the case of a fixed fault, the deviation 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.

[0138] Fig. 9 1 is a flowchart showing the processing executed by the controller 30 regarding the calculation of the required value of the behavior parameter taking into account the deviation reaction force. When the required value of the behavior parameter is calculated in the three-actuator control ( Figure 4 Step S200) is performed Fig. 9 The processing involved in the flowchart shown.

[0139] The processing involved in steps S221 and S222 is Figure 6 The processing involved in steps S211 and S212 is equivalent.

[0140] If the failure of the fourth actuator 26 - 4 is not a shutdown 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 i-th base required control force and the fourth base required control force without correcting the fourth base required control force.

[0141] When the failure of the fourth actuator 26 - 4 is a shutoff failure (step S223 ; Yes), the controller 30 calculates the generated deviation reaction force (step S224 , refer to equations (4) to (6)).

[0142] After step S224 , in step S225 , the controller 30 corrects the fourth base required control force calculated in step S221 by adding the deviation reaction force (see equation (7)).

[0143] 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.

[0144] Description of reference numerals:

[0145] 10 ... vehicle; 14 ... wheel; 20 ... suspension; 26 ... actuator; 30 ... controller; 32 ... processor; 34 ... memory; 36 ... computer program.

Claims

1. A vehicle behavior control device, wherein: have: First to fourth suspensions are provided on first to fourth wheels of the vehicle, respectively; and a controller, controlling the behavior of the vehicle, The first to fourth suspensions include first to fourth actuators for applying vertical control forces to the first to fourth wheels, respectively. When a fourth actuator other than the i-th actuator among the first to fourth actuators fails, the controller is configured as follows: calculating a required value of a behavior parameter representing the 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 behavior of the vehicle by controlling the i-th actuator based on the i-th required control force, Among them, i=1~3.

2. The vehicle behavior control device according to claim 1, wherein: The first to fourth actuators include first to fourth transmission members for transmitting reaction forces generated by deformation to the first to fourth wheels, respectively. The first to fourth actuators are configured to apply the control forces in the up-down direction to the first to fourth wheels by deforming the first to fourth transmission members, respectively. The deviation 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 and a time when the failure occurs and a time when the failure does not occur. The controller is configured to calculate the required value of the behavior parameter in consideration of the deviation reaction force.

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

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

5. The vehicle behavior control device according to claim 4, wherein: The controller is configured to perform force control on each of the first to fourth actuators. When the failure of the fourth actuator is fixation of an operating position, the controller is configured to calculate the required value of the behavior parameter so that the deviation reaction force is eliminated.

6. The vehicle behavior control device according to claim 5, wherein: The controller is also configured as follows: calculating an i-th basic required control force for the i-th wheel and a fourth basic required control force for the fourth wheel, The fourth basic required control force is corrected by subtracting the deviation reaction force from the fourth basic required control force, The required value of the behavior parameter is calculated based on the i-th basic required control force and the fourth basic required control force after correction.

7. The vehicle behavior control device according to claim 4, wherein: The controller is configured to perform force control on 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 output of the fourth actuator, the deviation reaction force is zero.

8. The vehicle behavior control device according to claim 4, wherein: The controller is configured to perform position control on 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 output of the fourth actuator, the controller is configured to calculate the required value of the behavior parameter so that the deviation reaction force is compensated.

9. The vehicle behavior control device according to claim 8, wherein: The controller is also configured as follows: calculating an i-th basic required control force for the i-th wheel and a fourth basic required control force for the fourth wheel, The fourth basic required control force is corrected by adding the deviation reaction force to the fourth basic required control force, The required value of the behavior parameter is calculated based on the i-th basic required control force and the fourth basic required control force after correction.

10. The vehicle behavior control device according to claim 4, wherein: The controller is configured to perform position control on each of the first to fourth actuators. When the failure of the fourth actuator is the fixation of the operating position, the deviation reaction force is zero.

11. A vehicle behavior control method for controlling the behavior of a vehicle, wherein: The vehicle includes first to fourth suspensions provided on first to fourth wheels, respectively. The first to fourth suspensions include first to fourth actuators for applying vertical control forces to the first to fourth wheels, respectively. The vehicle behavior control method comprises the following steps when a failure of a fourth actuator other than the i-th actuator among the first to fourth actuators is detected: calculating a required value of a behavior parameter representing the behavior of the vehicle; converting the required value of the behavior parameter into an i-th required control force for the i-th actuator; as well as controlling the behavior of the vehicle by controlling the i-th actuator based on the i-th required control force, Among them, i=1~3.

12. A computer program product comprising a vehicle behavior control program for causing a computer to execute control of the behavior of a vehicle, wherein: The vehicle includes first to fourth suspensions provided on first to fourth wheels, respectively. The first to fourth suspensions include first to fourth actuators for applying vertical control forces to the first to fourth wheels, respectively. The vehicle behavior control program causes the computer to execute the following processing when a failure of the fourth actuator other than the i-th actuator among the first to fourth actuators is detected: a process of calculating a required value of a behavior parameter representing the 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; as well as a process of controlling the behavior of the vehicle by controlling the i-th actuator based on the i-th required control force, Among them, i=1~3.

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