Vehicle motion control device and vehicle motion control program

Abstract

To provide a vehicle motion control device and a vehicle motion control program which can appropriately calculate availability that is restricted according to abnormality of actuators.SOLUTION: A vehicle motion control device 1 includes a control request unit 31 for outputting a yaw rate target value γ* for executing vehicle motion control, and a control platform 32. The control platform 32 includes an availability calculation part for calculating availability of actuators 11 to 14. The availability calculation part calculates an abnormality index relating to abnormality of the actuators 11 to 14, and calculates the availability so that the availability is set to be equal to or less the availability when a possibility of abnormality of the actuators 11 to 14 is low, when a possibility of abnormality of the actuators 11 to 14 indicated by the abnormality index is high.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a vehicle motion control device and a vehicle motion control program. [Background technology]

[0002] Conventionally, as described in, for example, Patent Document 1, there is a vehicle motion control system in which a control platform is provided between an application that outputs a control target value for executing vehicle motion control and an actuator that is controlled to realize vehicle motion according to the vehicle motion control. In the system of the document, the availability of the actuator is calculated, and a limit is imposed on this availability according to the vehicle state. The availability is a value indicating the degree to which the actuator can be operated at the time of calculation. Then, the control target value is compared with each availability before and after the limit, and whether or not to operate the actuator is determined according to the comparison result. This prevents abnormal behavior of the vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-96618 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, the availability of an actuator varies not only depending on the vehicle state but also depending on the presence or absence of an abnormality in the actuator. However, the above-mentioned Patent Document 1 does not disclose a specific method for limiting the availability in response to an abnormality in the actuator, and there is still room for improvement in this regard. [Means for solving the problem]

[0005] A vehicle motion control device that solves the above problem has as its control target a vehicle equipped with an actuator for realizing vehicle motion in accordance with vehicle motion control, and comprises a control platform provided between a control request unit that outputs a control target value for executing the vehicle motion control, and an actuator control unit that controls the operation of the actuator, and the control platform executes an availability calculation process that calculates the availability of the actuator, and a command value calculation process that calculates a command value for the actuator to be output to the actuator control unit based on the control target value and the availability, and the availability calculation process includes an abnormality index calculation process that calculates an abnormality index related to an abnormality of the actuator, and a process that calculates the availability so that it is lower than the availability when the possibility of an abnormality of the actuator is low, when the possibility of an abnormality of the actuator indicated by the abnormality index is high.

[0006] A vehicle motion control program that solves the above-mentioned problems is executed by a computer that has as its control object a vehicle equipped with an actuator for realizing vehicle motion in accordance with vehicle motion control, and is provided between a control request unit that outputs a control target value for executing the vehicle motion control, and an actuator control unit that controls the operation of the actuator, and causes the computer to execute an availability calculation process that calculates the availability of the actuator, and a command value calculation process that calculates a command value for the actuator to be output to the actuator control unit based on the control target value and the availability, and in the availability calculation process, causes the computer to execute an abnormality index calculation process that calculates an abnormality index related to an abnormality of the actuator, and, when the possibility of an abnormality of the actuator indicated by the abnormality index is high, a process that calculates the availability so that it is lower than the availability when the possibility of an abnormality of the actuator is low.

[0007] According to the above configurations, an abnormality index relating to an abnormality in an actuator is calculated, and the availability is calculated by reflecting this abnormality index, so that the availability can be appropriately calculated with restrictions imposed in accordance with the abnormality in the actuator.

[0008] In the above-mentioned vehicle motion control device, it is preferable that the availability calculation process further includes a gain calculation process that calculates a gain corresponding to the abnormality index, and a basic value calculation process that calculates an availability basic value, which is the availability when the actuator is normal, and that the availability calculation process is a process that calculates the availability based on the availability basic value and the gain.

[0009] According to the above configuration, since the abnormality index is expressed by a gain, it is possible to easily calculate the availability with a restriction imposed in accordance with the abnormality of the actuator. In the above-mentioned vehicle motion control device, it is preferable that the abnormality index calculation process is a process of calculating a plurality of the abnormality indexes, the gain calculation process is a process of calculating a plurality of the gains corresponding to the plurality of abnormality indexes, and the availability calculation process includes a minimum gain selection process of selecting the smallest minimum gain among the plurality of gains, and is a process of calculating the availability based on the availability basic value and the minimum gain.

[0010] According to the above-mentioned configuration, the availability of the actuator is calculated to be small based on the abnormality index that most severely indicates an abnormality in the actuator, thereby making it possible to suitably suppress the occurrence of abnormal behavior of the vehicle.

[0011] In the above-mentioned vehicle motion control device, it is preferable that the abnormality index includes an abnormality level which is a ratio between a value based on the command value and a value based on the actual value of the actuator corresponding to the command value, and the gain calculation process includes a process of calculating an abnormality level gain which is the gain corresponding to the abnormality level.

[0012] In the above vehicle motion control device, it is preferable that the actuator includes a steering actuator for steering the wheels of the vehicle, and in the gain calculation process related to the calculation of the availability of the steering actuator, the abnormality level gain is calculated to be smaller as the deviation of the abnormality level from "1" becomes greater.

[0013] In the calculation of the availability of the steering actuator, if the abnormality level is "1", the actual value can track the command value of the steering actuator, and it is considered that the possibility of an abnormality in the steering actuator is low. On the other hand, if the abnormality level is a value far from "1", the deviation between the command value and the actual value of the steering actuator becomes large, and it is considered that the possibility of an abnormality in the steering actuator is high. In the above configuration, the abnormality level gain becomes smaller as the deviation of the abnormality level from "1" becomes larger, i.e., the higher the possibility of an abnormality in the steering actuator becomes. This makes it possible to suitably reduce the availability of the steering actuator in accordance with the abnormality, and thereby suppress the occurrence of abnormal vehicle behavior.

[0014] In the above vehicle motion control device, it is preferable that the actuator includes a brake actuator which applies braking force to multiple wheels of the vehicle, and in the gain calculation process relating to the calculation of the availability of the brake actuator, when the abnormality level is less than "1", the abnormality level gain is calculated to be the same value as when the abnormality level is "1", and when the abnormality level is greater than "1", the abnormality level gain is calculated to be smaller as the abnormality level becomes larger.

[0015] In the calculation of the brake actuator availability, if the abnormality level is less than "1", there is a high possibility that an abnormality occurs in which the braking force applied by the brake actuator is too small. In this case, the brake actuator will not have a sufficient effect on the vehicle behavior. Therefore, even if the brake actuator availability is not reduced, the vehicle motion will not change excessively. On the other hand, if the abnormality level is greater than "1", there is a high possibility that an abnormality occurs in which the braking force is too large. In this case, if the brake actuator availability is not reduced, there is a risk of the vehicle motion changing excessively.

[0016] In consideration of this, in the above configuration, the abnormality level gain is reduced as the abnormality level increases only when the abnormality level is greater than 1. This makes it possible to suitably reduce the availability of the brake actuator in response to an abnormality, and thus to suitably suppress the occurrence of abnormal vehicle behavior.

[0017] In the above vehicle motion control device, it is preferable that the abnormality index includes a failure probability, which is a probability calculated based on the result of an abnormality judgment for the actuator, and the gain calculation process includes a process of calculating a failure probability gain, which is the gain corresponding to the failure probability.

[0018] In the above vehicle motion control device, it is preferable that the actuator includes a steering actuator that steers the wheels of the vehicle, and in the gain calculation process related to the calculation of the availability of the steering actuator, when the failure probability is greater than a normal judgment threshold, the failure probability gain is calculated to become smaller as the failure probability increases.

[0019] According to the above configuration, the greater the probability of the steering actuator failing, i.e., the greater the possibility that the steering actuator will not operate according to the command value, the smaller the failure probability gain becomes. This makes it possible to suitably reduce the availability of the steering actuator in response to an abnormality in the steering actuator, thereby making it possible to suppress the occurrence of abnormal vehicle behavior.

[0020] In the above vehicle motion control device, the actuator includes a brake actuator that applies braking force to multiple wheels of the vehicle, the actuator control unit includes a brake actuator control unit that controls the operation of the brake actuator, and the brake actuator control unit is configured to be switchable between either a first control mode in which braking force is applied independently to each of the multiple wheels, and a second control mode in which the same braking force is applied to the multiple wheels, and it is preferable that the control platform further performs signal output processing to output a switching signal for switching the brake actuator from the first control mode to the second control mode when the failure probability is greater than an abnormality judgment threshold.

[0021] According to the above configuration, when the probability of the brake actuator failing is high, i.e., when there is a high possibility that the brake actuator will not operate according to the command value, the brake actuator is controlled to apply the same braking force to each wheel. This prevents the vehicle from actively turning due to the operation of the brake actuator, thereby suppressing the occurrence of abnormal vehicle behavior. Effect of the Invention

[0022] According to the present invention, availability can be appropriately calculated with restrictions imposed in accordance with an abnormality in an actuator. [Brief description of the drawings]

[0023] [Figure 1] 1 is a schematic configuration diagram of a vehicle on which a vehicle motion control device is mounted; [Diagram 2] Block diagram of the control platform. [Diagram 3] FIG. 2 is a block diagram of an availability calculation unit. [Figure 4] Block diagram of the EPS availability calculation unit. [Diagram 5]FIG. 13 is an explanatory diagram showing a change in EPS failure probability gain with respect to a change in EPS failure probability. [Figure 6] FIG. 4 is an explanatory diagram showing a change in EPS angle ratio gain with respect to a change in EPS angle ratio. [Figure 7] Block diagram of the VGR availability calculation unit. [Figure 8] Block diagram of the ARS availability calculation unit. [Figure 9] Block diagram of the right front wheel BRK availability calculation unit. [Figure 10] 11 is an explanatory diagram showing a change in a BRK failure probability gain in response to a change in the BRK failure probability and switching of the control mode of the BRKECU. FIG. [Figure 11] FIG. 4 is a graph showing a change in a braking force ratio gain with respect to a change in a braking force ratio. [Figure 12] 5 is a graph showing an exemplary change in the EPS front wheel steering angle command value and the EPS front wheel steering angle. [Figure 13] 5 is a graph showing an exemplary change in the EPS front wheel steering angle command value and the EPS front wheel steering angle. [Figure 14] 5 is a graph showing an exemplary change in the EPS front wheel steering angle command value and the EPS front wheel steering angle. [Figure 15] 5 is a graph showing an exemplary change in the EPS front wheel steering angle command value and the EPS front wheel steering angle. [Figure 16] 5 is a graph showing an exemplary change in the EPS front wheel steering angle command value and the EPS front wheel steering angle. [Figure 17] 5 is a graph showing an exemplary change in the EPS front wheel steering angle command value and the EPS front wheel steering angle. [Figure 18] 5 is a graph showing an exemplary change in the EPS front wheel steering angle command value and the EPS front wheel steering angle. [Figure 19] 5 is a graph showing an exemplary change in the EPS front wheel steering angle command value and the EPS front wheel steering angle. [Figure 20] 5 is a graph showing an exemplary change in the EPS front wheel steering angle command value and the EPS front wheel steering angle. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, an embodiment of a vehicle motion control device and a vehicle motion control program will be described with reference to the drawings. (Overall composition) As shown in Fig. 1, a vehicle 2 on which a vehicle motion control device 1 is mounted has front wheels 3F and rear wheels 3R. The front wheels 3F include two wheels, a right front wheel and a left front wheel, and the rear wheels 3R ​​include two wheels, a right rear wheel and a left rear wheel. For convenience of explanation, only the right front wheel and the right rear wheel are illustrated in Fig. 1.

[0025] The vehicle 2 is equipped with an electric power steering actuator (hereinafter, EPS actuator) 11, a variable transmission ratio actuator (hereinafter, VGR actuator) 12, an active rear wheel steering actuator (hereinafter, ARS actuator) 13, and a brake actuator (hereinafter, BRK actuator) 14. The vehicle also is equipped with an EPSECU 15 that controls the operation of the EPS actuator 11, a VGRECU 16 that controls the operation of the VGR actuator 12, an ARSECU 17 that controls the operation of the ARS actuator 13, and a BRKECU 18 that controls the operation of the BRK actuator 14. The actuators 11 to 14 each correspond to an actuator for realizing vehicle motion. The ECUs 15 to 18 each correspond to an actuator control unit.

[0026] The EPSECU15 can be configured by a processing circuit including (1) one or more processors that operate according to a computer program (software), (2) one or more dedicated hardware circuits such as an application specific integrated circuit (ASIC) that executes at least some of the various processes, or (3) a combination thereof. The processor includes a CPU and memory such as RAM and ROM, and the memory stores program code or instructions configured to cause the CPU to execute the processes. The memory, i.e., a non-transitory computer-readable medium, includes any available medium that can be accessed by a general-purpose or dedicated computer. Various controls by the EPSECU15 are performed by the CPU executing a program stored in the memory for each predetermined calculation cycle. The VGRECU16, ARSECU17, and BRKECU18 can each be configured by a processing circuit including any of the above (1) to (3).

[0027] The EPS actuator 11 assists the driver's steering operation by applying a motor torque to a front wheel steering mechanism (not shown). As an example, a type of EPS actuator 11 that applies a motor torque to a column shaft of the front wheel steering mechanism is adopted. The EPSECU 15 controls the rotation angle of the motor that is the drive source of the EPS actuator 11, thereby controlling the front wheel steering angle θf, which is the steering angle of the front wheels 3F. In other words, the EPS actuator 11 corresponds to a steering actuator that steers the front wheels 3F. The front wheel steering angle θf is a positive value when it is, for example, an angle to the right of the neutral angle at which the vehicle 2 travels straight, and is a negative value when it is an angle to the left.

[0028] An EPS front wheel steering angle command value θe*, which will be described later, is input to the EPSECU 15 from the vehicle motion control device 1. The EPSECU 15 controls the operation of the EPS actuator 11 by executing angle feedback control so that the EPS front wheel steering angle θe becomes the EPS front wheel steering angle command value θe*. The EPS front wheel steering angle θe is the actual value of the steering angle realized by the EPS actuator 11, out of the front wheel steering angle θf, and can be calculated based on the rotation angle of the motor of the EPS actuator 11. The EPSECU 15 outputs the EPS front wheel steering angle θe to the vehicle motion control device 1.

[0029] The VGR actuator 12 varies the transmission ratio between the steering angle of a steering wheel (not shown) and the front wheel turning angle θf by adding rotation of a motor, which is a driving source, to the steering operation of the driver. The VGRECU 16 controls the front wheel turning angle θf by controlling the rotation angle added to the front wheel steering mechanism by the VGR actuator 12. In other words, the VGR actuator 12 corresponds to a steering actuator that steers the front wheels 3F.

[0030] A VGR front wheel steering angle command value θv*, which will be described later, is input to the VGRECU 16 from the vehicle motion control device 1. The VGRECU 16 controls the operation of the VGR actuator 12 by executing angle feedback control so that the VGR front wheel steering angle θv becomes the VGR front wheel steering angle command value θv*. The VGR front wheel steering angle θv is an actual value of the steering angle realized by the VGR actuator 12, out of the front wheel steering angle θf, and can be calculated based on the rotation angle of the motor of the VGR actuator 12. The VGRECU 16 outputs the VGR front wheel steering angle θv to the vehicle motion control device 1.

[0031] The ARS actuator 13 steers the rear wheels 3R ​​by applying a motor torque to a rear wheel steering mechanism (not shown). The ARSECU 17 controls the rotation angle of the motor that is the drive source of the ARS actuator 13, thereby controlling the rear wheel steering angle θr, which is the steering angle of the rear wheels 3R. In other words, the ARS actuator 13 corresponds to a steering actuator that steers the rear wheels 3R. The rear wheel steering angle θr is a positive value when it is, for example, an angle to the right of the neutral angle at which the vehicle 2 travels straight, and is a negative value when it is an angle to the left.

[0032] A rear wheel steering angle command value θr*, which will be described later, is input to the ARSECU 17 from the vehicle motion control device 1. The ARSECU 17 controls the operation of the ARS actuator 13 by executing angle feedback control so that the rear wheel steering angle θr becomes the rear wheel steering angle command value θr*. The rear wheel steering angle θr, which is an actual value, can be calculated based on the rotation angle of the motor of the ARS actuator 13. The ARSECU 17 outputs the rear wheel steering angle θr to the vehicle motion control device 1.

[0033] The BRK actuator 14 is an actuator that applies braking force to each of the front wheels 3F and the rear wheels 3R. The BRK actuator 14 is configured to be able to apply braking force independently to four wheels, namely the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel. The BRKECU 18 has a first control mode that controls the braking force applied to the four wheels separately, and a second control mode that controls the braking force applied to the four wheels so as to be the same. The BRKECU 18 is configured to be able to switch its control mode between the first control mode and the second control mode.

[0034] The BRKECU 18 receives braking force command values ​​Bfr*, Bfl*, Brr*, Brl* for the front wheels 3F and the rear wheels 3R, which will be described later, from the vehicle motion control device 1. The BRKECU 18 controls the operation of the BRK actuator 14 so that the braking forces Bfr, ​​Bfl, Brr, Brl applied to the front wheels 3F and the rear wheels 3R ​​become the braking force command values ​​Bfr*, Bfl*, Brr*, Brl*. The braking forces Bfr, ​​Bfl, Brr, Brl, which are actual values, can be calculated based on the hydraulic pressure in each brake cylinder of the front wheels 3F and the rear wheels 3R. The BRKECU 18 outputs the braking forces Bfr, ​​Bfl, Brr, Brl to the vehicle motion control device 1.

[0035] The vehicle 2 further includes a periphery monitoring device 21 that monitors the periphery, and a plurality of sensors 22 that acquire various state quantities of the vehicle. The periphery monitoring device 21 includes a camera and a radar. The periphery monitoring device monitors white lines on the road surface on which the vehicle 2 is traveling, obstacles on the path, and the like. The sensors 22 include a vehicle speed sensor that detects the vehicle speed V, a yaw rate sensor that detects the yaw rate γ of the vehicle 2, and a lateral acceleration sensor that detects the lateral acceleration Gy of the vehicle 2.

[0036] (Vehicle motion control device 1) The vehicle motion control device 1 can be configured by a processing circuit including any one of the above (1) to (3). Various controls by the vehicle motion control device 1 are performed by the CPU executing programs stored in the memory at predetermined calculation cycles. The programs include a vehicle motion control program for executing the vehicle motion control. In other words, the CPU of the vehicle motion control device 1 corresponds to a computer.

[0037] The vehicle motion control device 1 includes a control request unit 31 and a control platform 32. The control request unit 31 calculates a yaw rate target value γ* of the vehicle 2, which is a control target value for executing vehicle motion control. The control platform 32 calculates a command value to be output to the ECUs 15 to 18 based on the yaw rate target value γ*.

[0038] The command value output to the EPSECU 15 is an EPS front wheel steering angle command value θe* indicating a target value of the front wheel steering angle θf steered by the EPS actuator 11. The command value output to the VGRECU 16 is a VGR front wheel steering angle command value θv* indicating a target value of the front wheel steering angle θf steered by the VGR actuator 12. The command value output to the ARSECU 17 is a rear wheel steering angle command value θr* indicating a target value of the rear wheel steering angle θr. The command values ​​output to the BRKECU 18 are a right front wheel braking force command value Bfr* indicating a target value of the braking force applied to the right front wheel, a left front wheel braking force command value Bfl* indicating a target value of the braking force applied to the left front wheel, a right rear wheel braking force command value Brr* indicating a target value of the braking force applied to the right rear wheel, and a left rear wheel braking force command value Brl* indicating a target value of the braking force applied to the left rear wheel.

[0039] (Control request unit 31) The control request unit 31 has one or more applications 33 that execute calculations to realize various vehicle motion controls. Examples of vehicle motion controls include lane keeping control, emergency avoidance control, and automatic parking control. Lane keeping control is for controlling vehicle motion so that the vehicle 2 does not deviate from the center of the driving lane. Emergency avoidance control is for controlling vehicle motion so as to avoid collision with an obstacle or the like present in front of the vehicle 2. Automatic parking control is for controlling vehicle motion so as to guide the vehicle 2 to a movement path expected when parking.

[0040] The control request unit 31 receives the surroundings monitoring information acquired by the surroundings monitoring device 21. Each application 33 calculates a target trajectory for realizing the corresponding vehicle motion control based on the surroundings monitoring information. The control request unit 31 calculates a yaw rate target value γ* for moving the vehicle 2 along the target trajectory.

[0041] In addition, when multiple requests are output simultaneously from multiple applications 33, the control request unit 31 arbitrates the target trajectories based on the requests and calculates the control target value based on the arbitration result. As an arbitration method, for example, a method of calculating the yaw rate target value γ* based on the target trajectory of the application 33 with high priority, or a method of calculating the yaw rate target value γ* based on a trajectory obtained by adding up multiple target trajectories can be adopted.

[0042] (Control Platform 32) As shown in Fig. 2, the control platform 32 executes each calculation process shown in each control block below at each predetermined calculation cycle to calculate command values ​​to be output to the ECUs 15 to 18. The control platform 32 includes an availability calculation unit 41 and a command value calculation unit 42. The availability calculation unit 41 receives as inputs a yaw rate target value γ*, a vehicle speed V, a yaw rate γ, a lateral acceleration Gy, an EPS front wheel steering angle θe, a VGR front wheel steering angle θv, a rear wheel steering angle θr, and braking forces Bfr, ​​Bfl, Brr, and Brl. The availability calculation unit 41 also receives as inputs an EPS front wheel steering angle command value θe*, a VGR front wheel steering angle command value θv*, a rear wheel steering angle command value θr*, and braking force command values ​​Bfr*, Bfl*, Brr*, and Brl* calculated by the command value calculation unit 42. The availability calculation unit 41 calculates the availability of the actuators 11 to 14, i.e., EPS availability Ae, VGR availability Av, ARS availability Ar, and BRK availability Abfr, Abfl, Abrr, and Abrl, based on these state quantities. That is, the availability calculation unit 41 executes the availability calculation process. The availability calculation unit 41 also generates a switching signal Ssw, which will be described later.

[0043] Here, the availability is a value indicating to what extent the actuators 11 to 14 can be operated at the time of calculation. In other words, the availability is a value indicating the controllable range of the actuators 11 to 14.

[0044] Specifically, EPS availability Ae includes EPS front wheel turning angle availability indicating the front wheel turning angle θf that can be steered by the operation of EPS actuator 11, and EPS front wheel turning angle change amount availability indicating the amount of change in the front wheel turning angle θf that can be steered during one calculation period. VGR availability Av includes VGR front wheel turning angle availability indicating the front wheel turning angle θf that can be steered by the operation of VGR actuator 12, and VGR front wheel turning angle change amount availability indicating the amount of change in the front wheel turning angle θf that can be steered during one calculation period. ARS availability Ar includes rear wheel turning angle availability indicating the rear wheel turning angle θr that can be steered by the operation of ARS actuator 13, and rear wheel turning angle change amount availability indicating the amount of change in the rear wheel turning angle θr that can be steered during one calculation period. The BRK availabilities Abfr, Abfl, Abrr, and Abrl include braking force availability indicating the braking force that can be applied to each of the front wheels 3F and rear wheels 3R ​​by operation of the BRK actuator 14, and braking force gradient availability indicating the amount of change in braking force that can be changed during one calculation period.

[0045] The command value calculation unit 42 receives the yaw rate target value γ*, the vehicle speed V, the yaw rate γ, the lateral acceleration Gy, the EPS availability Ae, the VGR availability Av, the ARS availability Ar, the BRK availability Abfr, Abfl, Abrr, Abrl, and the switching signal Ssw. The command value calculation unit 42 also receives the EPS front wheel steering angle θe, the VGR front wheel steering angle θv, the rear wheel steering angle θr, and the braking forces Bfr, ​​Bfl, Brr, Brl. The command value calculation unit 42 calculates command values ​​for the actuators 11 to 14 based on these state quantities. That is, the command value calculation unit 42 executes the command value calculation process.

[0046] Specifically, command value calculation unit 42 calculates a moment target value required to realize yaw rate target value γ* based on the state quantity input from sensor 22, and allocates this moment target value to actuators 11-14. Then, command value calculation unit 42 calculates EPS front wheel steering angle command value θe* within the range of EPS availability Ae so that the moment allocated to EPS actuator 11 is generated by the operation of the EPS actuator 11. In other words, command value calculation unit 42 calculates EPS front wheel steering angle command value θe* so that the absolute value of EPS front wheel steering angle command value θe* is equal to or less than EPS front wheel steering angle availability, and the difference between EPS front wheel steering angle command value θe* and EPS front wheel steering angle θe is equal to or less than EPS front wheel steering angle change amount availability.

[0047] Similarly, the command value calculation unit 42 calculates a VGR front wheel steering angle command value θv* within the range of VGR availability Av so that the moment allocated to the VGR actuator 12 is generated by the operation of the VGR actuator 12. The command value calculation unit 42 calculates a rear wheel steering angle command value θr* within the range of ARS availability Ar so that the moment allocated to the ARS actuator 13 is generated by the operation of the ARS actuator 13. The command value calculation unit 42 calculates braking force command values ​​Bfr*, Bfl*, Brr*, Brl* within the ranges of BRK availability Abfr, Abfl, Abrr, Abrl so that the moment allocated to the BRK actuator 14 is generated by the operation of the BRK actuator 14. When a switching signal Ssw indicating switching from the first control mode to the second control mode is input, the command value calculation unit 42 sets all of the braking force command values ​​Bfr*, Bfl*, Brr*, and Brl* to the same value.

[0048] As shown in FIG. 3, the availability calculation unit 41 includes an EPS availability calculation unit 51, a VGR availability calculation unit 52, an ARS availability calculation unit 53, and a BRK availability calculation unit .

[0049] The yaw rate target value γ*, the vehicle speed V, the yaw rate γ, the lateral acceleration Gy, the EPS front wheel steering angle command value θe*, and the EPS front wheel steering angle θe are input to the EPS availability calculation unit 51. The EPS availability calculation unit 51 calculates the EPS availability Ae based on these state quantities.

[0050] The VGR availability calculation unit 52 receives the yaw rate target value γ*, the vehicle speed V, the yaw rate γ, the lateral acceleration Gy, the VGR front wheel steering angle command value θv*, and the VGR front wheel steering angle θv. The VGR availability calculation unit 52 calculates the VGR availability Av based on these state quantities.

[0051] The yaw rate target value γ*, the vehicle speed V, the yaw rate γ, the lateral acceleration Gy, the rear wheel steering angle command value θr*, and the rear wheel steering angle θr are input to the ARS availability calculation unit 53. The ARS availability calculation unit 53 calculates the ARS availability Ar based on these state quantities.

[0052] The BRK availability calculation unit 54 receives the yaw rate target value γ*, the vehicle speed V, the yaw rate γ, the lateral acceleration Gy, the braking force command values ​​Bfr*, Bfl*, Brr*, Brl*, and the braking forces Bfr, ​​Bfl, Brr, Brl. The BRK availability calculation unit 54 calculates the right front wheel BRK availability Abfr, the left front wheel BRK availability Abfl, the right rear wheel BRK availability Abrr, and the left rear wheel BRK availability Abrl based on these state quantities. The BRK availability calculation unit 54 also generates a switching signal Ssw based on these state quantities.

[0053] (EPS Availability Calculation Unit 51) 4, EPS availability calculation unit 51 includes a first EPS abnormality determination unit 61, a second EPS abnormality determination unit 62, an EPS failure probability calculation unit 63, an EPS availability gain calculation unit 64, an EPS availability basic value calculation unit 65, and a multiplier 66. When the possibility of an abnormality in the EPS actuator 11, as indicated by the abnormality index related to the abnormality in the EPS actuator 11, is high, EPS availability calculation unit 51 calculates EPS availability Ae so that it is equal to or lower than EPS availability Ae when the possibility of an abnormality in the EPS actuator 11 is low.

[0054] In detail, the EPS front wheel steering angle command value θe* and the EPS front wheel steering angle θe are input to the first EPS abnormality determination unit 61. The first EPS abnormality determination unit 61 calculates an EPS angle deviation Δθe which is the difference between the EPS front wheel steering angle command value θe* and the EPS front wheel steering angle θe. The first EPS abnormality determination unit 61 compares the EPS angle deviation Δθe with a preset EPS angle deviation threshold value Δθeth. If the EPS angle deviation Δθe is greater than the EPS angle deviation threshold value Δθeth, the first EPS abnormality determination unit 61 determines that the EPS actuator 11 is abnormal in the first EPS abnormality determination. In this case, the first EPS abnormality determination unit 61 sets the value of the first EPS abnormality determination flag Fe1 to "1" and outputs it to the EPS failure probability calculation unit 63 and the EPS availability gain calculation unit 64. On the other hand, when the EPS angle deviation Δθe is equal to or smaller than the EPS angle deviation threshold Δθeth, the first EPS abnormality determination unit 61 determines that the EPS actuator 11 is normal in the first EPS abnormality determination. In this case, the first EPS abnormality determination unit 61 sets the value of the first EPS abnormality determination flag Fe1 to “0” and outputs it to the EPS failure probability calculation unit 63 and the EPS availability gain calculation unit 64.

[0055] The second EPS abnormality determination unit 62 receives the yaw rate target value γ* and the yaw rate γ. The second EPS abnormality determination unit 62 calculates a yaw rate deviation Δγ, which is the difference between the yaw rate target value γ* and the yaw rate γ. The second EPS abnormality determination unit 62 compares the yaw rate deviation Δγ with a preset yaw rate deviation threshold Δγth. If the yaw rate deviation Δγ is greater than the yaw rate deviation threshold Δγth, the second EPS abnormality determination unit 62 determines that the EPS actuator 11 is abnormal in the second EPS abnormality determination. In this case, the second EPS abnormality determination unit 62 sets the value of the second EPS abnormality determination flag Fe2 to "1" and outputs it to the EPS failure probability calculation unit 63. On the other hand, if the yaw rate deviation Δγ is equal to or less than the yaw rate deviation threshold Δγth, the second EPS abnormality determination unit 62 determines that the EPS actuator 11 is normal in the second EPS abnormality determination. In this case, second EPS abnormality determination unit 62 sets the value of second EPS abnormality determination flag Fe2 to “0” and outputs it to EPS failure probability calculation unit 63.

[0056] The first EPS abnormality determination flag Fe1 and the second EPS abnormality determination flag Fe2 are input to the EPS failure probability calculation unit 63. Based on these flags Fe1, Fe2, the EPS failure probability calculation unit 63 calculates an EPS failure probability Pe, which is the probability that the EPS actuator 11 has failed. The EPS failure probability Pe is an abnormality index related to an abnormality in the EPS actuator 11. In other words, the EPS failure probability calculation unit 63 executes an abnormality index calculation process. The EPS failure probability Pe calculated in this manner is output to the EPS availability gain calculation unit 64.

[0057] Specifically, the EPS failure probability calculation unit 63 includes a map that defines the relationship between the values ​​of the flags Fe1 and Fe2 and the EPS failure probability Pe. The EPS failure probability calculation unit 63 calculates the EPS failure probability Pe according to the values ​​of the flags Fe1 and Fe2 by referring to this map. As an example of the map, when the values ​​of the flags Fe1 and Fe2 are all "0", the EPS failure probability Pe is set to "0%", and when the values ​​of the flags Fe1 and Fe2 are all "1", the EPS failure probability Pe is set to "100%". As another example, when the value of the first EPS abnormality determination flag Fe1 is "1" and the value of the second EPS abnormality determination flag Fe2 is "0", the EPS failure probability Pe is set to "70%", and when the value of the first EPS abnormality determination flag Fe1 is "0" and the value of the second EPS abnormality determination flag Fe2 is "1", the EPS failure probability Pe is set to "60%".

[0058] The EPS availability gain calculation unit 64 receives the EPS front wheel steering angle command value θe*, the EPS front wheel steering angle θe, the first EPS abnormality determination flag Fe1, and the EPS failure probability Pe. The EPS availability gain calculation unit 64 calculates an EPS failure probability gain Gpe and an EPS angle ratio gain Gre based on these state quantities. The EPS availability gain calculation unit 64 then outputs the smaller of the EPS failure probability gain Gpe and the EPS angle ratio gain Gre, i.e., the minimum gain, as the EPS availability gain Gae to the multiplier 66. In other words, the EPS availability gain calculation unit 64 executes a gain calculation process and a minimum gain selection process. The EPS failure probability gain Gpe and the EPS angle ratio gain Gre are each a value between "0" and "1".

[0059] First, the calculation of the EPS failure probability gain Gpe will be described. The EPS availability gain calculation unit 64 calculates the EPS failure probability gain Gpe based on the EPS failure probability Pe. Specifically, when the EPS failure probability Pe is equal to or greater than "0%" and equal to or less than the normality determination threshold Peth1, the EPS availability gain calculation unit 64 calculates the EPS failure probability gain Gpe to be "1". When the EPS failure probability Pe is greater than the normality determination threshold Peth1 and equal to or less than the abnormality determination threshold Peth2, the EPS availability gain calculation unit 64 calculates the EPS failure probability gain Gpe to be smaller as the EPS failure probability Pe increases. When the EPS failure probability Pe is greater than the abnormality determination threshold Peth2 and equal to or less than "100%, the EPS availability gain calculation unit 64 calculates the EPS failure probability gain Gpe to be "0". The normality determination threshold Peth1 is the maximum probability at which the EPS actuator 11 can be considered normal, and is set to, for example, "50%". The abnormality determination threshold Peth2 is the minimum probability at which it is acceptable to consider that the EPS actuator 11 is malfunctioning, and is set to, for example, "80%."

[0060] 5, the EPS failure probability gain Gpe remains constant at "1" when the EPS failure probability Pe is equal to or less than the normality determination threshold Peth1. When the EPS failure probability Pe is greater than the normality determination threshold Peth1, the EPS failure probability gain Gpe decreases as the EPS failure probability Pe increases.

[0061] Next, the calculation of the EPS angle ratio gain Gre will be described. As shown in Fig. 4, EPS availability gain calculation unit 64 calculates EPS angle ratio Re by dividing EPS front wheel turning angle θe by EPS front wheel turning angle command value θe*. Therefore, EPS angle ratio Re indicates the extent to which EPS front wheel turning angle θe follows EPS front wheel turning angle command value θe*, and is an abnormality index related to an abnormality of EPS actuator 11. Note that EPS angle ratio Re may be referred to as EPS abnormality level, or simply as abnormality level. In other words, EPS availability gain calculation unit 64 executes abnormality index calculation processing.

[0062] While the value of the first EPS abnormality determination flag Fe1 is "0," the EPS availability gain calculation unit 64 calculates the EPS angle ratio gain Gre to be "1" regardless of the EPS angle ratio Re. Then, while the value of the first EPS abnormality determination flag Fe1 is "1," the EPS availability gain calculation unit 64 changes the EPS angle ratio gain Gre in accordance with the EPS angle ratio Re.

[0063] Specifically, when the EPS angle ratio Re is "1", the EPS availability gain calculation unit 64 calculates the EPS angle ratio gain Gre to be "1". When the first EPS abnormality determination flag Fe1 is "1", the EPS availability gain calculation unit 64 calculates the EPS angle ratio gain Gre to be smaller as the EPS angle ratio Re becomes smaller than "1". When the EPS angle ratio Re is "0" or less, the EPS availability gain calculation unit 64 calculates the EPS angle ratio gain Gre to be "0". Furthermore, when the value of the first EPS abnormality determination flag Fe1 is "1", the EPS availability gain calculation unit 64 calculates the EPS angle ratio gain Gre to be smaller as the EPS angle ratio Re becomes larger than "1". The EPS availability gain calculation unit 64 calculates the EPS angle ratio gain Gre as "0" when the EPS angle ratio Re is greater than the sum of "1" and the EPS angle ratio threshold value Reth.

[0064] 6, the EPS angle ratio gain Gre is calculated so that, with "1" as its maximum value, it linearly decreases as the EPS angle ratio Re becomes smaller than "1". Also, the EPS angle ratio gain Gre is calculated so that, with "1" as its maximum value, it linearly decreases as the EPS angle ratio Re becomes larger than "1". In other words, EPS availability gain calculation unit 64 calculates the EPS angle ratio gain Gre to be smaller as the EPS angle ratio Re deviates from "1" more.

[0065] As shown in Fig. 4, the vehicle speed V and the lateral acceleration Gy are input to the EPS availability base value calculation unit 65. The EPS availability base value calculation unit 65 calculates the EPS availability base value Ae_b based on these state quantities. That is, the EPS availability base value calculation unit 65 executes a base value calculation process. The EPS availability base value Ae_b is the availability when the EPS actuator 11 is normal, and changes according to the motion state of the vehicle. Specifically, the EPS availability base value Ae_b changes according to the reaction force that the front wheels 3F receive from the road surface.

[0066] Specifically, the EPS availability base value calculation unit 65 stores an EPS performance availability Ae_n determined by the performance of the EPS actuator 11. The EPS availability base value calculation unit 65 calculates a coefficient Ke based on the vehicle speed V, the lateral acceleration Gy, and the like. For example, the coefficient Ke is calculated to be smaller as the vehicle speed V is higher and as the lateral acceleration Gy is higher. The EPS availability base value calculation unit 65 then multiplies the EPS performance availability Ae_n by the coefficient Ke to calculate an EPS availability base value Ae_b. The EPS availability base value Ae_b calculated in this manner is output to a multiplier 66.

[0067] The EPS availability gain Gae and the EPS availability base value Ae_b are input to the multiplier 66. Then, the EPS availability calculation unit 51 calculates the EPS availability Ae by multiplying the EPS availability base value Ae_b by the EPS availability gain Gae in the multiplier 66. The EPS availability Ae calculated in this manner is output to the command value calculation unit 42 as described above.

[0068] (VGR availability calculation unit 52) 7, the VGR availability calculation unit 52 includes a first VGR abnormality determination unit 71, a second VGR abnormality determination unit 72, a VGR failure probability calculation unit 73, a VGR availability gain calculation unit 74, a VGR availability basic value calculation unit 75, and a multiplier 76. When the possibility of an abnormality in the VGR actuator 12 indicated by the abnormality index related to the abnormality in the VGR actuator 12 is high, the VGR availability calculation unit 52 calculates the VGR availability Av to be equal to or less than the VGR availability Av when the possibility of an abnormality in the VGR actuator 12 is low.

[0069] In detail, the VGR front wheel steering angle command value θv* and the VGR front wheel steering angle θv are input to the first VGR abnormality determination unit 71. The first VGR abnormality determination unit 71 calculates a VGR angle deviation Δθv, which is a deviation between the VGR front wheel steering angle command value θv* and the VGR front wheel steering angle θv. The first VGR abnormality determination unit 71 compares the VGR angle deviation Δθv with a preset VGR angle deviation threshold value Δθvth. If the VGR angle deviation Δθv is greater than the VGR angle deviation threshold value Δθvth, the first VGR abnormality determination unit 71 determines that the VGR actuator 12 is abnormal in the first VGR abnormality determination. In this case, the first VGR abnormality determination unit 71 sets the value of the first VGR abnormality determination flag Fv1 to "1" and outputs it to the VGR failure probability calculation unit 73 and the VGR availability gain calculation unit 74. On the other hand, when the VGR angle deviation Δθv is equal to or smaller than the VGR angle deviation threshold Δθvth, the first VGR abnormality determination unit 71 determines that the VGR actuator 12 is normal in the first VGR abnormality determination. In this case, the first VGR abnormality determination unit 71 sets the value of the first VGR abnormality determination flag Fv1 to “0” and outputs it to the VGR failure probability calculation unit 73 and the VGR availability gain calculation unit 74.

[0070] The yaw rate target value γ* and the yaw rate γ are input to the second VGR abnormality determination unit 72. The second VGR abnormality determination unit 72 executes the same abnormality determination as the second EPS abnormality determination unit 62, and outputs a second VGR abnormality determination flag Fv2 indicating the determination result to the VGR failure probability calculation unit 73.

[0071] The first VGR abnormality determination flag Fv1 and the second VGR abnormality determination flag Fv2 are input to the VGR failure probability calculation unit 73. Based on these flags Fv1 and Fv2, the VGR failure probability calculation unit 73 calculates a VGR failure probability Pv, which is the probability that the VGR actuator 12 is malfunctioning, in the same manner as the EPS failure probability calculation unit 63. The VGR failure probability Pv is an abnormality index related to the abnormality of the VGR actuator 12. In other words, the VGR failure probability calculation unit 73 executes an abnormality index calculation process. The VGR failure probability Pv calculated in this manner is output to the VGR availability gain calculation unit 74.

[0072] The VGR availability gain calculation unit 74 receives the VGR front wheel steering angle command value θv*, the VGR front wheel steering angle θv, the first VGR abnormality determination flag Fv1, and the VGR failure probability Pv. Based on these state quantities, the VGR availability gain calculation unit 74 calculates the VGR failure probability gain Gpv and the VGR angle ratio gain Grv in the same manner as the EPS availability gain calculation unit 64. The VGR availability gain calculation unit 74 then outputs the smaller of the VGR failure probability gain Gpv and the VGR angle ratio gain Grv, that is, the minimum gain, as the VGR availability gain Gav to the multiplier 76. That is, the VGR availability gain calculation unit 74 executes the gain calculation process and the minimum gain selection process. The VGR failure probability gain Gpv and the VGR angle ratio gain Grv are each a value between "0" and "1", inclusive.

[0073] The vehicle speed V and the lateral acceleration Gy are input to the VGR availability basic value calculation unit 75. The VGR availability basic value calculation unit 75 calculates the VGR availability basic value Av_b based on these state quantities, similar to the EPS availability basic value calculation unit 65. That is, the VGR availability basic value calculation unit 75 executes a basic value calculation process. The VGR availability basic value Av_b is the availability when the VGR actuator 12 is normal, and changes according to the motion state of the vehicle. Specifically, the VGR availability basic value Av_b changes according to the reaction force that the front wheels 3F receive from the road surface. The VGR availability basic value Av_b calculated in this manner is output to the multiplier 76.

[0074] The VGR availability gain Gav and the VGR availability base value Av_b are input to the multiplier 76. Then, the VGR availability calculation unit 52 calculates the VGR availability Av by multiplying the VGR availability base value Av_b by the VGR availability gain Gav in the multiplier 76. The VGR availability Av calculated in this manner is output to the command value calculation unit 42 as described above.

[0075] (ARS Availability Calculation Unit 53) 8, the ARS availability calculation unit 53 includes a first ARS abnormality determination unit 81, a second ARS abnormality determination unit 82, an ARS failure probability calculation unit 83, an ARS availability gain calculation unit 84, an ARS availability basic value calculation unit 85, and a multiplier 86. When the possibility of an abnormality in the ARS actuator 13 indicated by the abnormality index related to the abnormality in the ARS actuator 13 is high, the ARS availability calculation unit 53 calculates the ARS availability Ar to be equal to or less than the ARS availability Ar when the possibility of an abnormality in the ARS actuator 13 is low.

[0076] In detail, the rear wheel steering angle command value θr* and the rear wheel steering angle θr are input to the first ARS abnormality determination unit 81. The first ARS abnormality determination unit 81 calculates the ARS angle deviation Δθr, which is the difference between the rear wheel steering angle command value θr* and the rear wheel steering angle θr. The first ARS abnormality determination unit 81 compares the ARS angle deviation Δθr with a preset ARS angle deviation threshold value Δθrth. If the ARS angle deviation Δθr is greater than the ARS angle deviation threshold value Δθrth, the first ARS abnormality determination unit 81 determines that the ARS actuator 13 is abnormal in the first ARS abnormality determination. In this case, the first ARS abnormality determination unit 81 sets the value of the first ARS abnormality determination flag Fr1 to "1" and outputs it to the ARS failure probability calculation unit 83 and the ARS availability gain calculation unit 84. On the other hand, when the ARS angle deviation Δθr is equal to or smaller than the ARS angle deviation threshold Δθrth, the first ARS abnormality determination unit 81 determines that the ARS actuator 13 is normal in the first ARS abnormality determination. In this case, the first ARS abnormality determination unit 81 sets the value of the first ARS abnormality determination flag Fr1 to “0” and outputs it to the ARS failure probability calculation unit 83 and the ARS availability gain calculation unit 84.

[0077] The yaw rate target value γ* and the yaw rate γ are input to the second ARS abnormality determination unit 82. The second ARS abnormality determination unit 82 executes the same abnormality determination as the second EPS abnormality determination unit 62, and outputs a second ARS abnormality determination flag Fr2 indicating the determination result to the ARS failure probability calculation unit 83.

[0078] The first ARS abnormality determination flag Fr1 and the second ARS abnormality determination flag Fr2 are input to the ARS failure probability calculation unit 83. The ARS failure probability calculation unit 83 calculates an ARS failure probability Pr, which is the probability that the ARS actuator 13 is abnormal, based on these flags Fr1 and Fr2, in the same manner as the EPS failure probability calculation unit 63. The ARS failure probability Pr is an abnormality index related to an abnormality of the ARS actuator 13. In other words, the ARS failure probability calculation unit 83 executes an abnormality index calculation process. The ARS failure probability Pr calculated in this manner is output to the ARS availability gain calculation unit 84.

[0079] The ARS availability gain calculation unit 84 receives the rear wheel steering angle command value θr*, the rear wheel steering angle θr, the first ARS abnormality determination flag Fr1, and the ARS failure probability Pr. Based on these state quantities, the ARS availability gain calculation unit 84 calculates the ARS failure probability gain Gpr and the ARS angle ratio gain Grr in the same manner as the EPS availability gain calculation unit 64. The ARS availability gain calculation unit 84 then outputs the smaller of the ARS failure probability gain Gpr and the ARS angle ratio gain Grr, that is, the minimum gain, as the ARS availability gain Gar to the multiplier 86. That is, the ARS availability gain calculation unit 84 executes a gain calculation process and a minimum gain selection process. The ARS failure probability gain Gpr and the ARS angle ratio gain Grr are each a value between "0" and "1", inclusive.

[0080] The ARS availability basic value calculation unit 85 receives the vehicle speed V and the lateral acceleration Gy. Based on these state quantities, the ARS availability basic value calculation unit 85 calculates the ARS availability basic value Ar_b in the same manner as the EPS availability basic value calculation unit 65. That is, the ARS availability basic value calculation unit 85 executes a basic value calculation process. The ARS availability basic value Ar_b is the availability when the ARS actuator 13 is normal, and changes according to the motion state of the vehicle. Specifically, the ARS availability basic value Ar_b changes according to the reaction force that the rear wheel 3R receives from the road surface. The ARS availability basic value Ar_b calculated in this manner is output to the multiplier 86.

[0081] The ARS availability gain Gar and the ARS availability base value Ar_b are input to the multiplier 86. Then, the ARS availability calculation unit 53 calculates the ARS availability Ar by multiplying the ARS availability base value Ar_b by the ARS availability gain Gar in the multiplier 86. The ARS availability Ar calculated in this manner is output to the command value calculation unit 42 as described above.

[0082] (BRK Availability Calculation Unit 54) As shown in FIG. 3, the BRK availability calculation unit 54 includes a right front wheel BRK availability calculation unit 54a, a left front wheel BRK availability calculation unit 54b, a right rear wheel BRK availability calculation unit 54c, and a left rear wheel BRK availability calculation unit 54d.

[0083] The right front wheel BRK availability calculation unit 54a receives the vehicle speed V, the yaw rate γ, the lateral acceleration Gy, the right front wheel braking force command value Bfr*, and the right front wheel braking force Bfr. The right front wheel BRK availability calculation unit 54a calculates the right front wheel BRK availability Abfr based on these state quantities and generates a switching signal Ssw.

[0084] The left front wheel BRK availability calculation unit 54b receives the vehicle speed V, the yaw rate γ, the lateral acceleration Gy, the left front wheel braking force command value Bfl*, and the left front wheel braking force Bfl. The left front wheel BRK availability calculation unit 54b calculates the left front wheel BRK availability Abfl based on these state quantities and generates a switching signal Ssw.

[0085] The right rear wheel BRK availability calculation unit 54c receives the vehicle speed V, the yaw rate γ, the lateral acceleration Gy, the right rear wheel braking force command value Brr*, and the right rear wheel braking force Brr. The right rear wheel BRK availability calculation unit 54c calculates the right rear wheel BRK availability Abrr based on these state quantities and generates a switching signal Ssw.

[0086] The left rear wheel BRK availability calculation unit 54d receives the vehicle speed V, the yaw rate γ, the lateral acceleration Gy, the left rear wheel braking force command value Brl*, and the left rear wheel braking force Brl. The left rear wheel BRK availability calculation unit 54d calculates the left rear wheel BRK availability Abrl based on these state quantities and generates a switching signal Ssw.

[0087] Here, the calculations by the right front wheel BRK availability calculation unit 54a, the left front wheel BRK availability calculation unit 54b, the right rear wheel BRK availability calculation unit 54c, and the left rear wheel BRK availability calculation unit 54d are performed in the same manner. Therefore, only the calculations by the right front wheel BRK availability calculation unit 54a will be described, and the explanations of the calculations by the left front wheel BRK availability calculation unit 54b, the right rear wheel BRK availability calculation unit 54c, and the left rear wheel BRK availability calculation unit 54d will be omitted.

[0088] 9, the right front wheel BRK availability calculation unit 54a includes a first BRK abnormality determination unit 91, a second BRK abnormality determination unit 92, a BRK failure probability calculation unit 93, a BRK availability gain calculation unit 94, a BRK availability basic value calculation unit 95, and a multiplier 96. When the possibility of an abnormality in the BRK actuator 14 is high as indicated by the abnormality index related to the abnormality of the BRK actuator 14, the right front wheel BRK availability calculation unit 54a calculates the BRK availability Abfr to be equal to or less than the BRK availability Abfr when the possibility of an abnormality in the BRK actuator 14 is low.

[0089] In detail, the right front wheel braking force command value Bfr* and the right front wheel braking force Bfr are input to the first BRK abnormality determination unit 91. The first BRK abnormality determination unit 91 calculates a braking force deviation ΔBfr which is the difference between the right front wheel braking force command value Bfr* and the right front wheel braking force Bfr. The first BRK abnormality determination unit 91 compares the braking force deviation ΔBfr with a preset braking force deviation threshold value ΔBth. If the braking force deviation ΔBfr is greater than the braking force deviation threshold value ΔBth, the first BRK abnormality determination unit 91 determines that the BRK actuator 14 is abnormal in the first BRK abnormality determination. In this case, the first BRK abnormality determination unit 91 sets the value of the first BRK abnormality determination flag Fbfr1 to "1" and outputs it to the BRK failure probability calculation unit 93 and the BRK availability gain calculation unit 94. On the other hand, when the braking force deviation ΔBfr is equal to or smaller than the braking force deviation threshold ΔBth, the first BRK abnormality determination unit 91 determines that the BRK actuator 14 is normal in the first BRK abnormality determination. In this case, the first BRK abnormality determination unit 91 sets the value of the first BRK abnormality determination flag Fbfr1 to “0” and outputs it to the BRK failure probability calculation unit 93 and the BRK availability gain calculation unit 94.

[0090] The yaw rate target value γ* and the yaw rate γ are input to the second BRK abnormality determination unit 92. The second BRK abnormality determination unit 92 executes the same abnormality determination as the second EPS abnormality determination unit 62, and outputs the second BRK abnormality determination flag Fbfr2 indicating the determination result to the BRK failure probability calculation unit 93.

[0091] The first BRK abnormality determination flag Fbfr1 and the second BRK abnormality determination flag Fbfr2 are input to the BRK failure probability calculation unit 93. Based on these flags Fbfr1 and Fbfr2, the BRK failure probability calculation unit 93 calculates a BRK failure probability Pbfr, which is the probability that the BRK actuator 14 is abnormal, in the same manner as the EPS failure probability calculation unit 63. The BRK failure probability Pbfr is an abnormality index related to an abnormality of the BRK actuator 14. In other words, the BRK failure probability calculation unit 93 executes an abnormality index calculation process. The BRK failure probability Pbfr calculated in this manner is output to the BRK availability gain calculation unit 94.

[0092] The right front wheel braking force command value Bfr*, the right front wheel braking force Bfr, ​​the first BRK abnormality determination flag Fbfr1, and the BRK failure probability Pbfr are input to the BRK availability gain calculation unit 94. The BRK availability gain calculation unit 94 calculates the BRK failure probability gain Gpbfr and the braking force ratio gain Grbfr based on these state quantities. Then, the BRK availability gain calculation unit 94 outputs the smaller of the BRK failure probability gain Gpbfr and the braking force ratio gain Grbfr, that is, the minimum gain, as the BRK availability gain Gabfr to the multiplier 96. That is, the BRK availability gain calculation unit 94 executes the gain calculation process and the minimum gain selection process. The BRK failure probability gain Gpbfr and the braking force ratio gain Grbfr are each a value between "0" and "1", inclusive.

[0093] First, the calculation of the BRK failure probability gain Gpbfr will be described. The BRK availability gain calculation unit 94 calculates the BRK failure probability gain Gpbfr or generates the switching signal Ssw based on the BRK failure probability Pbfr. Specifically, the BRK availability gain calculation unit 94 calculates the BRK failure probability gain Gpbfr as "1" regardless of the BRK failure probability Pbfr. On the other hand, when the BRK failure probability Pbfr is greater than the abnormality determination threshold Pbth2 and is equal to or less than "100%", the BRK availability gain calculation unit 94 generates the switching signal Ssw. The abnormality determination threshold Pbth2 is the minimum probability at which it is acceptable to consider the BRK actuator 14 to be in failure, and is set to, for example, "80%". The BRK availability gain Gabfr calculated in this manner is output to the multiplier 96, and the switching signal Ssw is output to the command value calculation unit 42.

[0094] 10, the BRK failure probability gain Gpbfr remains constant at "1" regardless of the BRK failure probability Pbfr. When the BRK failure probability Pbfr is equal to or less than the abnormality determination threshold Pbth2, the BRK actuator 14 is controlled in the first control mode. On the other hand, when the BRK failure probability Pbfr is greater than the abnormality determination threshold Pbth2, the BRK actuator 14 is controlled in the second control mode.

[0095] Next, the calculation of the braking force ratio gain Grbfr will be described. As shown in Fig. 9, the BRK availability gain calculation unit 94 calculates the braking force ratio Rbfr by dividing the right front wheel braking force Bfr by the right front wheel braking force command value Bfr*. Therefore, the braking force ratio Rbfr indicates the extent to which the right front wheel braking force Bfr is able to follow the right front wheel braking force command value Bfr*, and is an abnormality index related to an abnormality of the BRK actuator 14. The braking force ratio Rbfr may be referred to as a BRK abnormality level or simply an abnormality level. In other words, the BRK availability gain calculation unit 94 executes an abnormality index calculation process.

[0096] The BRK availability gain calculation unit 94 calculates the braking force ratio gain Grbfr as "1" regardless of the braking force ratio Rbfr while the value of the first BRK abnormality determination flag Fbfr1 is "0". Then, the BRK availability gain calculation unit 94 changes the braking force ratio gain Grbfr according to the braking force ratio Rbfr while the value of the first BRK abnormality determination flag Fbfr1 is "1".

[0097] Specifically, when the braking force ratio Rbfr is "1", the BRK availability gain calculation unit 94 calculates the braking force ratio gain Grbfr as "1". When the braking force ratio Rbfr is smaller than "1", the BRK availability gain calculation unit 94 calculates the braking force ratio gain Grbfr as "1" even if the braking force ratio Rbfr is "0" or less. When the value of the first BRK abnormality determination flag Fbfr1 is "1", the BRK availability gain calculation unit 94 calculates the braking force ratio gain Grbfr to be smaller as the braking force ratio Rbfr becomes larger than "1". When the braking force ratio Rbfr is larger than the sum of "1" and the braking force ratio threshold value Rbth, the BRK availability gain calculation unit 94 calculates the braking force ratio gain Grbfr as "0".

[0098] 11, the braking force ratio gain Grbfr remains constant at "1" when the braking force ratio Rbfr is equal to or less than "1". On the other hand, the braking force ratio gain Grbfr is calculated so as to linearly decrease from a maximum value of "1" as the braking force ratio Rbfr becomes larger than "1".

[0099] As shown in FIG. 9, the vehicle speed V and the lateral acceleration Gy are input to the BRK availability base value calculation unit 95. The BRK availability base value calculation unit 95 calculates the BRK availability base value Abfr_b based on these state quantities, similar to the EPS availability base value calculation unit 65. That is, the BRK availability base value calculation unit 95 executes a base value calculation process. The BRK availability base value Abfr_b is the availability when the BRK actuator 14 is normal, and changes according to the motion state of the vehicle. Specifically, the BRK availability base value Abfr_b changes according to the reaction force that the right front wheel receives from the road surface. The BRK availability base value Abfr_b calculated in this manner is output to the multiplier 96.

[0100] The BRK availability gain Gabfr and the BRK availability basic value Abfr_b are input to the multiplier 96. Then, the right front wheel BRK availability calculation unit 54a calculates the right front wheel BRK availability Abfr by multiplying the BRK availability basic value Abfr_b by the BRK availability gain Gabfr in the multiplier 96. The right front wheel BRK availability Abfr calculated in this manner is output to the command value calculation unit 42 as described above.

[0101] (Example of operation) Next, an example of the operation of the actuators 11 to 14 will be described. As described above, the VGR availability Av and the ARS availability Ar are calculated in the same manner as the EPS availability Ae. Therefore, if the change tendency of the VGR front wheel steering angle θv relative to the VGR front wheel steering angle command value θv* is the same as the change tendency of the EPS front wheel steering angle θe relative to the EPS front wheel steering angle command value θe*, the operation of the VGR actuator 12 is restricted in the same manner as the EPS actuator 11. Also, if the change tendency of the rear wheel steering angle θr relative to the rear wheel steering angle command value θr* is the same as the change tendency of the EPS front wheel steering angle θe relative to the EPS front wheel steering angle command value θe*, the operation of the ARS actuator 13 is restricted in the same manner as the EPS actuator 11. Therefore, hereinafter, a description of the operation of the VGR actuator 12 and the ARS actuator 13 will be omitted. Also, in Figs. 12 to 20, the EPS front wheel steering angle command value θe* is indicated by a solid line, and the EPS front wheel steering angle θe is indicated by a broken line.

[0102] (Example 1) For example, as shown in FIG. 12, assume that the EPS front wheel steering angle θe can almost follow the EPS front wheel steering angle command value θe* until time t1, but after time t1, the increase in the EPS front wheel steering angle θe is insufficient relative to the increase in the EPS front wheel steering angle command value θe*, and the EPS angle ratio Re gradually decreases. In this case, the EPS angle ratio gain Gre is calculated as "1" until time t2 when the EPS angle deviation Δθe becomes larger than the EPS angle deviation threshold value Δθeth and the value of the first EPS abnormality determination flag Fe1 becomes "1". Also, in this case, if the second EPS abnormality determination based on the comparison of the magnitude between the yaw rate target value γ* and the yaw rate γ determines that the EPS is normal, the EPS failure probability gain Gpe is calculated as "1". Therefore, the EPS availability gain Gae is calculated as "1", and the EPS availability Ae becomes the EPS availability basic value Ae_b, which is the availability when the EPS availability Ae is normal. As a result, until time t2, the operation of the EPS actuator 11 is controlled in the normal manner so as to realize vehicle motion in accordance with the vehicle motion control.

[0103] After time t2, when the EPS angle deviation Δθe becomes larger than the EPS angle deviation threshold Δθeth, the value of the first EPS abnormality determination flag Fe1 becomes "1". Then, the EPS angle ratio gain Gre is calculated to become smaller according to the decrease in the EPS angle ratio Re. Also, as the value of the first EPS abnormality determination flag Fe1 becomes "1", the EPS failure probability increases, and the EPS failure probability gain Gpe is calculated to become smaller. Therefore, the EPS availability gain Gae becomes smaller than "1", and the EPS availability Ae becomes smaller than the EPS availability basic value Ae_b. As a result, after time t2, the operation of the EPS actuator 11 is controlled in a limited state according to the EPS availability Ae so as to realize vehicle motion according to the vehicle motion control. This suppresses the occurrence of abnormal behavior of the vehicle 2.

[0104] The situation in which the operation of the EPS actuator 11 is restricted in this manner is not limited to the case shown in Fig. 12. For example, as shown in Fig. 13, even if the EPS front wheel steering angle θe decreases after time t1 despite the EPS front wheel steering angle command value θe* increasing, the situation in which the operation of the EPS actuator 11 is restricted is also similarly generated.

[0105] Next, the operation of the BRK actuator 14 will be described. Assume that the right front wheel braking force command value Bfr* and the right front wheel braking force Bfr change in the same manner as the EPS front wheel steering angle command value θe* and the EPS front wheel steering angle θe shown in FIG. 12 or FIG. 13, for example, so that the braking force ratio Rbfr becomes smaller. Even if the braking force ratio Rbfr becomes smaller, the braking force ratio gain Grbfr remains at "1". Therefore, when a switching signal Ssw for switching from the first control mode to the second control mode is not output, the operation of the BRK actuator 14 is normally controlled in the first control mode so as to realize vehicle motion according to the vehicle motion control. That is, the braking force applied to each wheel is controlled independently. On the other hand, when the BRK failure probability Pbfr becomes larger than the abnormality determination threshold value Pbth2, the operation of the BRK actuator 14 is controlled in the second control mode. That is, the braking force applied to each wheel is controlled to be the same. As a result, the operation of the BRK actuator 14 is not controlled in order to actively turn the vehicle 2.

[0106] (Example 2) For example, as shown in Fig. 14, assume that the EPS front wheel steering angle θe can almost follow the EPS front wheel steering angle command value θe* until time t1, but after time t1, the EPS front wheel steering angle θe increases excessively in response to an increase in the EPS front wheel steering angle command value θe*, and the EPS angle ratio Re gradually increases. In this case, the EPS angle ratio gain Gre is calculated to be "1" until time t2, as in the case shown in Fig. 12 or 13, for example, and is calculated to decrease as the EPS angle ratio Re increases after time t2. Then, when the EPS angle ratio Re becomes larger than the sum of "1" and the EPS angle ratio threshold value Reth at time t3, the EPS angle ratio gain Gre is calculated to be "0" thereafter.

[0107] As a result, until time t2, the operation of the EPS actuator 11 is controlled normally to realize vehicle motion in accordance with the vehicle motion control. After time t2, the operation of the EPS actuator 11 is controlled in a limited state in accordance with the EPS availability Ae to realize vehicle motion in accordance with the vehicle motion control. After time t3, the operation of the EPS actuator 11 is no longer controlled to execute the vehicle motion control.

[0108] The situation in which the operation of the EPS actuator 11 is restricted in this manner is not limited to the case shown in Fig. 14. For example, as shown in Fig. 15, even if the EPS front wheel steering angle θe increases after time t1 despite the EPS front wheel steering angle command value θe* decreasing, the situation in which the operation of the EPS actuator 11 is restricted is also reached.

[0109] Next, the operation of the BRK actuator 14 will be described. It is assumed that the braking force ratio Rbfr increases as a result of the right front wheel braking force command value Bfr* and the right front wheel braking force Bfr changing in the same manner as the EPS front wheel steering angle command value θe* and the EPS front wheel steering angle θe shown in FIG. 14 or FIG. 15. In this case, the braking force ratio gain Grbfr is calculated as "1" until time t2 when the braking force deviation ΔBfr becomes greater than the braking force deviation threshold ΔBth and the value of the first BRK abnormality determination flag Fbfr1 becomes "1". After time t2, the braking force ratio gain Grbfr is calculated to become smaller as the braking force ratio Rbfr increases. Then, when the braking force ratio Rbfr becomes greater than the sum of "1" and the braking force ratio threshold Rbth at time t3, the braking force ratio gain Grbfr is calculated as "0" thereafter.

[0110] As a result, until time t2, the operation of the BRK actuator 14 is normally controlled in the first control mode so as to realize vehicle motion according to the vehicle motion control. After time t2, the operation of the BRK actuator 14 is controlled in a limited state according to the BRK availabilities Abfr, Abfl, Abrr, and Abrl so as to realize vehicle motion according to the vehicle motion control. After time t3, the operation of the BRK actuator 14 is no longer controlled in order to execute the vehicle motion control. Also, even before time t3, if the BRK failure probability Pbfr becomes larger than the abnormality determination threshold value Pbth2, the operation of the BRK actuator 14 is no longer controlled in order to actively turn the vehicle 2.

[0111] (Example 3) For example, as shown in Fig. 16, assume that the EPS front wheel steering angle command value θe* and the EPS front wheel steering angle θe are both "0" until time t1, and that after time t1, the EPS front wheel steering angle θe increases even though the EPS front wheel steering angle command value θe* remains constant at "0". In this case, the EPS angle ratio gain Gre is calculated as "1" until time t2 when the EPS angle deviation Δθe becomes greater than the EPS angle deviation threshold Δθeth. After time t2, the EPS angle ratio Re becomes infinite, and so the EPS angle ratio gain Gre is calculated as "0".

[0112] As a result, if the second EPS abnormality determination does not determine that there is an abnormality, the operation of EPS actuator 11 is controlled normally until time t2 to realize vehicle motion in accordance with vehicle motion control. After time t2, the operation of EPS actuator 11 is no longer controlled in order to execute vehicle motion control.

[0113] Next, the operation of the BRK actuator 14 will be described. Assume that the right front wheel braking force command value Bfr* and the right front wheel braking force Bfr change in the same manner as the EPS front wheel steering angle command value θe* and the EPS front wheel steering angle θe shown in Fig. 16, for example, so that the braking force ratio Rbfr becomes infinite. In this case, until time t2, the braking force ratio gain Grbfr is calculated as "1". After time t2, the braking force ratio Rbfr becomes infinite, so the braking force ratio gain Grbfr is calculated as "0".

[0114] As a result, until time t2, the operation of the BRK actuator 14 is normally controlled in the first control mode to realize vehicle motion according to the vehicle motion control. After time t2, the operation of the BRK actuator 14 is no longer controlled to execute the vehicle motion control. Furthermore, even before time t2, if the BRK failure probability Pbfr becomes larger than the abnormality determination threshold value Pbth2, the operation of the BRK actuator 14 is no longer controlled to actively turn the vehicle 2.

[0115] (Example 4) For example, as shown in Fig. 17, assume that the EPS front wheel steering angle command value θe* and the EPS front wheel steering angle θe are each "0" until time t1, and that even if the EPS front wheel steering angle command value θe* increases after time t1, the EPS front wheel steering angle θe does not change and the EPS angle ratio Re is "0". In this case, until time t2 when the EPS angle deviation Δθe becomes larger than the EPS angle deviation threshold Δθeth, the EPS angle ratio gain Gre is calculated as "1". After time t2, the EPS angle ratio gain Gre is calculated as "0".

[0116] As a result, if the second EPS abnormality determination does not determine that there is an abnormality, the operation of EPS actuator 11 is controlled normally until time t2 to realize vehicle motion in accordance with vehicle motion control. After time t2, the operation of EPS actuator 11 is no longer controlled in order to execute vehicle motion control.

[0117] It should be noted that the situation in which the operation of EPS actuator 11 is restricted in this manner is not limited to the case shown in Fig. 17. For example, as shown in Fig. 18, even if the EPS front wheel steering angle command value θe* is a constant positive value, the operation of EPS actuator 11 is similarly restricted even if the EPS front wheel steering angle θe decreases to a negative value after time t1.

[0118] Next, the operation of the BRK actuator 14 will be described. Assume that the right front wheel braking force command value Bfr* and the right front wheel braking force Bfr change in the same manner as the EPS front wheel steering angle command value θe* and the EPS front wheel steering angle θe shown in FIG. 17 or FIG. 18, for example, so that the braking force ratio Rbfr becomes "0" or less. In this case, even if the braking force ratio Rbfr becomes small, the braking force ratio gain Grbfr remains "1". Therefore, when the BRK failure probability Pbfr is equal to or less than the abnormality determination threshold value Pbth2, the operation of the BRK actuator 14 is normally controlled in the first control mode so as to realize vehicle motion according to the vehicle motion control. Note that, when the BRK failure probability Pbfr becomes larger than the abnormality determination threshold value Pbth2, the operation of the BRK actuator 14 is no longer controlled in order to actively turn the vehicle 2.

[0119] (Example 5) For example, as shown in Fig. 19, assume that the EPS front wheel steering angle θe fluctuates slightly after time t1 when the EPS front wheel steering angle command value θe* is a positive constant value. In other words, assume that the EPS angle deviation Δθe is equal to or less than the EPS angle deviation threshold Δθeth, the value of the first EPS abnormality determination flag Fe1 remains "0", and the EPS front wheel steering angle θe follows the EPS front wheel steering angle command value θe*. In this case, the EPS angle ratio gain Gre is continuously calculated as "1". As a result, if the second EPS abnormality determination does not determine that there is an abnormality, the operation of the EPS actuator 11 is controlled normally to realize vehicle motion in accordance with the vehicle motion control.

[0120] Next, the operation of the BRK actuator 14 will be described. Assume that the right front wheel braking force command value Bfr* and the right front wheel braking force Bfr change in the same manner as the EPS front wheel steering angle command value θe* and the EPS front wheel steering angle θe shown in FIG. 19, for example. In this case, the braking force deviation ΔBfr is equal to or less than the braking force deviation threshold ΔBth, and the value of the first BRK abnormality determination flag Fbfr1 is "0", so that the braking force ratio gain Grbfr remains at "1". Therefore, when the BRK failure probability Pbfr is equal to or less than the abnormality determination threshold Pbth2, the operation of the BRK actuator 14 is normally controlled in the first control mode so as to realize vehicle motion according to the vehicle motion control. Note that, when the BRK failure probability Pbfr becomes larger than the abnormality determination threshold Pbth2, the operation of the BRK actuator 14 is no longer controlled in order to actively turn the vehicle 2.

[0121] (Example 6) For example, as shown in Fig. 20, assume that the EPS front wheel steering angle θe fluctuates greatly after time t1 when the EPS front wheel steering angle command value θe* is a constant positive value. Specifically, after time t1, the EPS front wheel steering angle θe decreases, and at time t2, the EPS angle deviation Δθe becomes larger than the EPS angle deviation threshold Δθeth. Thereafter, the EPS front wheel steering angle θe becomes a negative value and then starts to increase, and at time t4, the EPS angle deviation Δθe becomes equal to or smaller than the EPS angle deviation threshold Δθeth. Then, the EPS front wheel steering angle θe continues to increase, and at time t5, the EPS angle deviation Δθe becomes larger than the EPS angle deviation threshold Δθeth.

[0122] In this case, EPS angle ratio gain Gre is calculated as "1" until time t2. After time t2, EPS angle ratio gain Gre gradually decreases, reaches "0" once, and then gradually increases. Then, after EPS angle ratio gain Gre reaches "1" at time t4, it remains at "1" until time t5. After time t5, EPS angle ratio gain Gre gradually decreases.

[0123] As a result, if the second EPS abnormality determination does not determine that there is an abnormality, the operation of the EPS actuator 11 is controlled normally until time t2 to realize vehicle motion in accordance with the vehicle motion control. After time t2, the operation of the EPS actuator 11 is controlled in a limited state in accordance with the EPS availability Ae, and once the vehicle motion control is executed, the operation of the EPS actuator 11 is not controlled. Thereafter, the operation of the EPS actuator 11 is again controlled in a limited state in accordance with the EPS availability Ae to realize vehicle motion in accordance with the vehicle motion control. After time t4, the operation of the EPS actuator 11 is controlled normally. Then, after time t5, the operation of the EPS actuator 11 is controlled in a limited state in accordance with the EPS availability Ae.

[0124] Next, the operation of the BRK actuator 14 will be described. It is assumed that the right front wheel braking force command value Bfr* and the right front wheel braking force Bfr change in the same manner as the EPS front wheel steering angle command value θe* and the EPS front wheel steering angle θe shown in Fig. 20. In this case, the braking force ratio gain Grbfr is calculated as "1" from time t2 to time t5. After time t5, the braking force ratio gain Grbfr gradually becomes smaller.

[0125] Therefore, when the BRK failure probability Pbfr is equal to or less than the abnormality determination threshold Pbth2, the operation of the BRK actuator 14 is normally controlled in the first control mode so as to realize vehicle motion according to the vehicle motion control until time t5. After time t5, the operation of the BRK actuator 14 is controlled in a limited state according to the BRK availabilities Abfr, Abfl, Abrr, and Abrl so as to realize vehicle motion according to the vehicle motion control. Note that, even before time t5, if the BRK failure probability Pbfr becomes greater than the abnormality determination threshold Pbth2, the operation of the BRK actuator 14 is no longer controlled in order to actively turn the vehicle 2.

[0126] Next, the operation and effects of this embodiment will be described. (1) The EPS availability calculation unit 51 calculates the EPS angle ratio Re and the EPS failure probability Pe. When the possibility of an abnormality in the EPS actuator 11 is high, as indicated by the EPS angle ratio Re and the EPS failure probability Pe, the EPS availability calculation unit 51 calculates the EPS availability Ae so that it is equal to or less than the EPS availability Ae when the possibility of an abnormality in the EPS actuator 11 is low. In this way, the EPS availability calculation unit 51 calculates the EPS availability Ae by reflecting the EPS angle ratio Re and the EPS failure probability Pe. Therefore, it is possible to appropriately calculate the EPS availability Ae with a restriction added according to the abnormality in the EPS actuator 11. The same can be said about the VGR availability Av, the ARS availability Ar, and the BRK availability Abfr, Abfl, Abrr, and Abrl.

[0127] (2) The EPS availability calculation unit 51 calculates an EPS angle ratio gain Gre according to the EPS angle ratio Re, an EPS failure probability gain Gpe according to the EPS failure probability Pe, and an EPS availability basic value Ae_b. The EPS availability calculation unit 51 calculates the EPS availability Ae based on the EPS availability basic value Ae_b, the EPS angle ratio gain Gre, and the EPS failure probability gain Gpe. Since the EPS angle ratio Re and the EPS failure probability Pe are each expressed by a gain in this way, it is possible to easily calculate the EPS availability Ae with a restriction imposed in accordance with an abnormality in the EPS actuator 11. The same can be said about the VGR availability Av, the ARS availability Ar, and the BRK availability Abfr, Abfl, Abrr, and Abrl.

[0128] (3) The EPS availability calculation unit 51 selects the smallest minimum gain among the EPS angle ratio gain Gre and the EPS failure probability gain Gpe, and calculates the EPS availability Ae based on the EPS availability basic value Ae_b and the minimum gain. Therefore, the EPS availability Ae is calculated to be small based on the abnormality index that most severely indicates an abnormality in the EPS actuator 11. This makes it possible to suitably suppress the occurrence of abnormal behavior of the vehicle 2. The same can be said about the VGR availability Av, the ARS availability Ar, and the BRK availability Abfr, Abfl, Abrr, and Abrl.

[0129] (4) The EPS availability calculation unit 51 calculates the EPS angle ratio gain Gre so that the greater the deviation of the EPS angle ratio Re from "1", the smaller the EPS angle ratio gain Gre becomes. When the EPS angle ratio Re is "1", the EPS front wheel steering angle θe, which is the actual value, can follow the EPS front wheel steering angle command value θe*, and it is considered that the possibility of an abnormality in the EPS actuator 11 is low. On the other hand, when the EPS angle ratio Re is a value far from "1", the deviation between the EPS front wheel steering angle command value θe* and the EPS front wheel steering angle θe becomes large, and it is considered that the possibility of an abnormality in the EPS actuator 11 is high. And, in the above configuration, the larger the deviation of the EPS angle ratio Re from "1", that is, the higher the possibility of an abnormality in the EPS actuator 11, the smaller the EPS angle ratio gain Gre is. Thereby, the EPS availability Ae can be suitably reduced according to the abnormality in the EPS actuator 11, and the occurrence of abnormal behavior of the vehicle 2 can be suppressed. The same can be said about the VGR availability Av and the ARS availability Ar.

[0130] (5) When the braking force ratio Rbfr is less than "1", the BRK availability calculation unit 54 calculates the braking force ratio gain Grbfr to be the same value as when the braking force ratio Rbfr is "1". On the other hand, when the braking force ratio Rbfr is greater than "1", the BRK availability calculation unit 54 calculates the braking force ratio gain Grbfr to be smaller as the braking force ratio Rbfr increases.

[0131] When the braking force ratio Rbfr is less than "1", the possibility of an abnormality in which the braking force applied by the BRK actuator 14 is too small increases. In this case, the BRK actuator 14 cannot sufficiently affect the behavior of the vehicle 2. Therefore, even if the BRK availability Abfr, Abfl, Abrr, and Abrl are not reduced, the vehicle motion will not change excessively. On the other hand, when the braking force ratio Rbfr is greater than "1", the possibility of an abnormality in which the braking force is excessive increases. In this case, unless the BRK availability Abfr, Abfl, Abrr, and Abrl are reduced, the vehicle motion may change excessively. In light of this, in the above configuration, only when the braking force ratio Rbfr is greater than "1", the braking force ratio gain Grbfr decreases as the braking force ratio Rbfr increases. This makes it possible to suitably reduce the BRK availability in response to an abnormality in the BRK actuator 14, and thus to suitably suppress the occurrence of abnormal behavior of the vehicle 2.

[0132] (6) When the EPS failure probability Pe is greater than the normality determination threshold Peth1, the EPS availability calculation unit 51 calculates the EPS failure probability gain Gpe to be smaller as the EPS failure probability Pe increases. Therefore, the EPS failure probability gain Gpe becomes smaller as the failure probability of the EPS actuator 11 increases, that is, as the possibility that the EPS actuator 11 does not operate according to the EPS front wheel steering angle command value θe* increases. This makes it possible to suitably reduce the EPS availability Ae in response to an abnormality in the EPS actuator 11, and thus to suppress the occurrence of abnormal behavior of the vehicle 2. The same can be said about the VGR availability Av and the ARS availability Ar.

[0133] (7) When the BRK failure probability Pbfr becomes equal to or greater than the abnormality determination threshold value Pbth2, the BRK availability calculation unit 54 outputs a switching signal Ssw for switching the control mode of the BRKECU 18 from the first control mode to the second control mode. Therefore, when the failure probability of the BRK actuator 14 is high, that is, when there is a high possibility that the BRK actuator 14 will not operate according to the braking force command values ​​Bfr*, Bfl*, Brr*, and Brl*, the BRK actuator 14 is controlled to apply the same braking force to each wheel. As a result, the vehicle 2 is not actively turned by the operation of the BRK actuator 14, so that the occurrence of abnormal behavior of the vehicle 2 can be suppressed.

[0134] This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs. In the above embodiment, when the BRK failure probability Pbfr becomes equal to or greater than the abnormality determination threshold value Pbth2, the switching signal Ssw for switching the control mode of the BRKECU 18 from the first control mode to the second control mode does not need to be output.

[0135] In the above embodiment, the value of the EPS failure probability gain Gpe calculated based on the EPS failure probability Pe can be changed as appropriate. For example, when the EPS failure probability Pe is greater than the normality determination threshold Peth1 and is equal to or less than the abnormality determination threshold Peth2, the EPS failure probability gain Gpe may be calculated as "1". Also, for example, when the EPS failure probability Pe is equal to or less than the normality determination threshold Peth1, the EPS failure probability gain Gpe may be calculated to be smaller as the EPS failure probability Pe increases. The same can be said about the VGR failure probability gain Gpv and the ARS failure probability gain Gpr.

[0136] In addition, the value of the BRK failure probability gain Gpbfr calculated based on the BRK failure probability Pbfr can be changed as appropriate. For example, the BRK failure probability gain Gpbfr may be set to a different value when the BRK failure probability Pbfr is equal to or less than the normality determination threshold Pbth1 and when the BRK failure probability Pbfr is greater than the normality determination threshold Pbth1 and equal to or less than the abnormality determination threshold Pbth2.

[0137] In the above embodiment, the EPS failure probability Pe is calculated by map calculation, but this is not limiting, and the EPS failure probability Pe may be calculated by other methods, such as calculation using a function formula, etc. This modification can be similarly applied to the calculation of the VGR failure probability Pv, the ARS failure probability Pr, and the BRK failure probability Pbfr.

[0138] In the above embodiment, the value of the EPS angle ratio gain Gre calculated based on the EPS angle ratio Re can be changed as appropriate. In the above embodiment, the EPS angle ratio gain Gre is set to "1" while the value of the first EPS abnormality determination flag Fe1 is "0", but this is not limited to this. For example, even while the value of the first EPS abnormality determination flag Fe1 is "0", the EPS angle ratio gain Gre may be calculated to be smaller as the deviation of the EPS angle ratio Re from "1" increases. In other words, the EPS angle ratio gain Gre may be immediately changed in response to a change in the EPS angle ratio Re. This modification can be similarly applied to the calculation of the VGR angle ratio gain Grv and the ARS angle ratio gain Grr.

[0139] Also, the value of the braking force ratio gain Grbfr calculated based on the braking force ratio Rbfr can be changed as appropriate. For example, when the braking force ratio Rbfr is greater than the sum of "1" and the braking force ratio threshold value Rbth, the braking force ratio gain Grbfr may be calculated to be a certain lower limit value greater than "0". Also, when the braking force ratio Rbfr is less than "1", the braking force ratio gain Grbfr may be calculated to be smaller as the braking force ratio Rbfr becomes smaller. Furthermore, for example, even while the value of the first BRK abnormality determination flag Fbfr1 is "0", the braking force ratio gain Grbfr may be calculated to be smaller as the braking force ratio Rbfr becomes greater than "1".

[0140] In the above embodiment, the EPS angle ratio Re is referred to as the EPS abnormality level, but this is not limiting. For example, the EPS angle deviation Δθe may be referred to as the EPS abnormality level. In this configuration, the case where the EPS angle deviation Δθe is a positive value corresponds to the case where the EPS angle ratio Re is greater than "1". Also, the case where the EPS angle deviation Δθe is a negative value corresponds to the case where the EPS angle ratio Re is smaller than "1". Note that the EPS availability gain calculation unit 64 can use the EPS angle deviation Δθe calculated in the process in which the first EPS abnormality determination unit 61 executes the first EPS abnormality determination. This modification can be similarly applied to the case where the VGR availability gain Gav, the ARS availability gain Gar, and the BRK availability gain Gabfr are calculated.

[0141] In the above embodiment, the EPS performance availability Ae_n is stored in the EPS availability basic value calculation unit 65, but this is not limiting. For example, the EPS availability basic value calculation unit 65 may acquire the EPS performance availability Ae_n from outside through communication. In addition, the calculation method of the EPS availability basic value Ae_b may be changed as appropriate, and the coefficient Ke may be calculated based on a state quantity other than the vehicle speed V and the lateral acceleration Gy. Furthermore, for example, the road surface μ on which the vehicle 2 is traveling may be acquired, and the EPS availability basic value Ae_b may be calculated taking the acquired road surface μ into consideration. The same applies to the calculation of the VGR availability basic value Av_b, the ARS availability basic value Ar_b, and the BRK availability basic value Abfr_b.

[0142] In the above embodiment, the EPS availability calculation unit 51 calculates the EPS availability Ae using the EPS availability base value Ae_b calculated by the EPS availability base value calculation unit 65, but this is not limited to the above. For example, the EPSECU15 may be configured to calculate the EPS availability base value, and the EPS availability calculation unit 51 may calculate the EPS availability Ae using this EPS availability base value. This modification can be similarly applied to the calculation of the VGR availability Av, the ARS availability Ar, and the BRK availability Abfr, Abfl, Abrr, and Abrl.

[0143] In the above embodiment, the smaller of the EPS failure probability gain Gpe and the EPS angle ratio gain Gre is set as the EPS availability gain Gae. However, this is not limiting, and for example, a value obtained by multiplying the EPS failure probability gain Gpe and the EPS angle ratio gain Gre may be calculated as the EPS availability gain Gae. Also, the EPS availability gain calculation unit 64 may be configured to calculate only one of the EPS failure probability gain Gpe and the EPS angle ratio gain Gre, and this one gain may be set as the EPS availability gain Gae. These modifications can be similarly applied to the VGR availability gain Gav, the ARS availability gain Gar, and the BRK availability gain Gabfr.

[0144] In the above embodiment, the EPS availability calculation unit 51 performs the first EPS abnormality determination and the second EPS abnormality determination, but the present invention is not limited to this. Only one EPS abnormality determination may be performed, or three or more EPS abnormality determinations may be performed. As a method of EPS abnormality determination, for example, abnormality determination based on the deviation between a lateral acceleration target value for realizing vehicle motion control and an actual lateral acceleration may be adopted. In addition, for example, for abnormality determination based on the EPS angle deviation Δθe, multiple EPS angle deviation thresholds may be set. Specifically, for example, a first EPS angle deviation threshold and a second EPS angle deviation threshold greater than the first EPS angle deviation threshold are set. Then, a comparison of the magnitude between the EPS angle deviation Δθe and the first EPS angle deviation threshold is set as the 1-1 EPS abnormality determination, and a comparison of the magnitude between the EPS angle deviation Δθe and the second EPS angle deviation threshold is set as the 1-2 EPS abnormality determination. These modifications can be similarly applied to the VGR availability calculation unit 52, the ARS availability calculation unit 53, and the BRK availability calculation unit 54.

[0145] In the above embodiment, when the availability of the actuators 11 to 14 becomes smaller than a threshold value, the driver may be notified of the fact by a notification device such as a display or a speaker.

[0146] In the above embodiment, the control request unit 31 calculates the yaw rate target value γ*, which is the control target value, based on the surroundings monitoring information acquired by the surroundings monitoring device 21, but is not limited to this, and the yaw rate target value γ* may be calculated taking into account other information. For example, the control request unit 31 may calculate the yaw rate target value γ* taking into account the availability calculated by the control platform 32 in addition to the surroundings monitoring information.

[0147] In the above embodiment, the availability calculation unit 41 outputs the availability of the actuators 11 to 14 to the command value calculation unit 42. However, the present invention is not limited to this and may output the availability to, for example, an external device outside the vehicle motion control device 1.

[0148] In the above embodiment, the control target value is the yaw rate target value γ*, but the control target value is not limited to this, and may be, for example, a lateral acceleration target value of the vehicle 2 or a slip angle target value of the vehicle 2. In addition, the control target value may be a target trajectory of the vehicle 2 according to vehicle motion control, or a command value for the actuators 11 to 14.

[0149] In the above embodiment, the method of calculating the command values ​​for the actuators 11 to 14 by the command value calculation unit 42 can be changed as appropriate. In the above embodiment, the actuators 11 to 14 are mounted on the vehicle 2 as actuators for realizing vehicle motion according to the vehicle motion control, but this is not limiting and at least one of the actuators 11 to 14 may be mounted on the vehicle. Also, in addition to or instead of the actuators 11 to 14, other actuators may be mounted on the vehicle. Examples of other actuators include actuators that control the driving force of each wheel, such as in-wheel motors, and steering actuators that steer the front wheels 3F in a steer-by-wire steering device.

[0150] In the above embodiment, the vehicle motion control device 1 is configured to include the control request unit 31 and the control platform 32, but this is not limiting. For example, the vehicle motion control device 1 may be configured to include only the control platform 32, and a control target value may be input from an externally provided control request unit. The vehicle motion control device 1 may also be incorporated in any one of the ECUs 15 to 18. In other words, any one of the ECUs 15 to 18 may have the function of the vehicle motion control device 1.

[0151] In the above embodiment, the availability of the actuators 11 to 14 may not be calculated, and only the switching signal Ssw for switching the control mode of the BRKECU 18 from the first control mode to the second control mode based on the BRK failure probability may be output.

[0152] Next, the technical ideas that can be understood from the above embodiment and modifications will be described below together with their effects. (i) A vehicle motion control device having a vehicle as a control target equipped with an actuator for realizing vehicle motion in accordance with vehicle motion control, the vehicle motion control device comprising: a control request unit that outputs a control target value for executing the vehicle motion control; and an actuator control unit that controls operation of the actuator, the actuator including a brake actuator that applies braking force to multiple wheels of the vehicle; the actuator control unit including a brake actuator control unit that controls operation of the brake actuator; the brake actuator control unit configured to be switchable between a first control mode in which braking force is applied independently to each of the multiple wheels; and a second control mode in which the same braking force is applied to the multiple wheels, the control platform performing a process of calculating a failure probability based on a result of an abnormality determination for the brake actuator; and a signal output process of outputting a switching signal for switching the brake actuator from the first control mode to the second control mode when the failure probability is greater than an abnormality determination threshold.

[0153] According to the above configuration, when the probability of the brake actuator failing is high, i.e., when there is a high possibility that the brake actuator will not operate according to the command value, the brake actuator is controlled to apply the same braking force to each wheel. This prevents the vehicle from actively turning due to the operation of the brake actuator, thereby suppressing the occurrence of abnormal vehicle behavior. [Explanation of symbols]

[0154] 1...Vehicle motion control device 2. Vehicle 11...EPS actuator 12...VGR actuator 13…ARS actuator 14...BRK actuator 15…EPSECU 16…VGRECU 17…ARSECU 18…BRKECU 31...Control request unit 32…Control platform

Claims

1. A vehicle to be controlled is equipped with an actuator for realizing vehicle motion according to vehicle motion control, A vehicle motion control device including a control platform provided between a control request unit that outputs a control target value for executing the vehicle motion control and an actuator control unit that controls an operation of the actuator, The control platform includes: an availability calculation process for calculating the availability of the actuator; a command value calculation process for calculating a command value of the actuator to be output to the actuator control unit based on the control target value and the availability; The availability calculation process includes: an abnormality index calculation process for calculating an abnormality index related to an abnormality of the actuator; and when the probability of an abnormality in the actuator indicated by the abnormality indicator is high, calculating the availability so that the availability is equal to or lower than the availability when the probability of an abnormality in the actuator is low; The availability calculation process includes: A gain calculation process that calculates a gain according to the abnormality indicator; A basic value calculation process for calculating an availability basic value, which is the availability when the actuator is normal, A vehicle motion control device, which is a process for calculating the availability based on the availability basic value and the gain.

2. 2. The vehicle motion control device according to claim 1, The abnormality indicator calculation process is a process of calculating a plurality of the abnormality indicators, the gain calculation process is a process of calculating a plurality of the gains according to the plurality of abnormality indicators, A vehicle motion control device, wherein the availability calculation process includes a minimum gain selection process that selects the smallest minimum gain from the plurality of gains, and is a process that calculates the availability based on the availability base value and the minimum gain.

3. The vehicle motion control device according to claim 1 or 2, the abnormality indicator includes an abnormality level that is a ratio between a value based on the command value and a value based on an actual value of the actuator corresponding to the command value; The vehicle motion control device, wherein the gain calculation process includes a process of calculating an abnormality level gain, which is the gain according to the abnormality level.

4. 4. The vehicle motion control device according to claim 3, The actuator includes a steering actuator that steers wheels of the vehicle, A vehicle motion control device, wherein in the gain calculation process relating to the calculation of the availability of the steering actuator, the abnormality level gain is calculated to be smaller as the deviation of the abnormality level from "1" increases.

5. 5. The vehicle motion control device according to claim 3, the actuator includes a brake actuator that applies a braking force to a plurality of wheels of the vehicle; In the gain calculation process related to the calculation of the availability of the brake actuator, the abnormality level gain is When the abnormality level is less than "1", the abnormality level is calculated to be the same value as when the abnormality level is "1", A vehicle motion control device, in which, when the abnormality level is greater than "1", the larger the abnormality level is, the smaller the calculation is made.

6. The vehicle motion control device according to any one of claims 1 to 5, the abnormality indicator includes a failure probability which is a probability calculated based on a result of an abnormality determination for the actuator, A vehicle motion control device, wherein the gain calculation process includes a process of calculating a failure probability gain, which is the gain corresponding to the failure probability.

7. 7. The vehicle motion control device according to claim 6, The actuator includes a steering actuator that steers wheels of the vehicle, A vehicle motion control device, in which in the gain calculation process related to the calculation of the availability of the steering actuator, the failure probability gain is calculated to be smaller as the failure probability increases when the failure probability is greater than a normality judgment threshold.

8. 8. The vehicle motion control device according to claim 6, the actuator includes a brake actuator that applies a braking force to a plurality of wheels of the vehicle; the actuator control unit includes a brake actuator control unit that controls operation of the brake actuator; the brake actuator control unit is configured to be switchable between a first control mode in which a braking force is applied independently to each of the plurality of wheels and a second control mode in which a same braking force is applied to the plurality of wheels, The vehicle motion control device, wherein the control platform further performs signal output processing to output a switching signal for switching the brake actuator from the first control mode to the second control mode when the failure probability is greater than an abnormality determination threshold.

9. A vehicle to be controlled is equipped with an actuator for realizing vehicle motion according to vehicle motion control, A vehicle motion control program executed by a computer provided between a control request unit that outputs a control target value for executing the vehicle motion control and an actuator control unit that controls an operation of the actuator, The computer includes: an availability calculation process for calculating the availability of the actuator; a command value calculation process for calculating a command value of the actuator to be output to the actuator control unit based on the control target value and the availability; In the availability calculation process, an abnormality index calculation process for calculating an abnormality index related to an abnormality of the actuator; and when the probability of an abnormality in the actuator is high as indicated by the abnormality indicator, a process of calculating the availability so that the availability is equal to or lower than the availability when the probability of an abnormality in the actuator is low; In the availability calculation process, A gain calculation process that calculates a gain according to the abnormality indicator; a basic value calculation process for calculating an availability basic value, which is the availability when the actuator is normal; a vehicle motion control program for causing a process of calculating the availability based on the availability basic value and the gain to be executed.

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