JP2006327271A - Vehicle control system and control method of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle control system and a control method of a vehicle capable of securing a robustness of systems on a vehicle loading the plurality of systems to control vehicle behavior. <P>SOLUTION: This vehicle control system is furnished with a steering angle sensor to detect a steering angle of a driver, an active steering means to add an auxiliary steering angle to a front wheel and/or a rear wheel so as to provide a desired vehicle behavioral characteristic in accordance with the steering angle, a vehicle behavioral state quantity detection means to detect state quantity of the vehicle behavior and an active brake means to respectively control braking force of the four wheels so as to provide the desired vehicle behavioral characteristic in accordance with the steering angle and the vehicle behavioral state quantity is further furnished with an abnormality detection means to detect abnormality of the active steering means and a first stopping means to continue the active brake means by stopping the active steer means by returning the auxiliary steering angle to neutral when the abnormality is detected by the abnormality detection means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle control system, and more particularly to a vehicle provided with a plurality of types of vehicle behavior control for obtaining desired vehicle behavior characteristics.

Conventionally, various technologies for vehicles equipped with a rear wheel rudder angle control system (hereinafter referred to as an active steering system) for controlling a rear wheel rudder angle so as to obtain a desired vehicle behavior characteristic have been proposed. (For example, refer to Patent Document 1). In this publication, when an abnormality of the active steering system is detected, the rear wheel steering angle is mechanically fixed, so that the vehicle behavior is stabilized even if the rear wheel steering angle is generated at the time of failure. Is.
Japanese Patent Laid-Open No. 2-74470

  In recent years, an active brake system that controls vehicle behavior by brake hydraulic pressure control acting on each wheel has been generally installed in vehicles. This active brake system includes a yaw rate sensor that detects an actual yaw rate acting on the vehicle, and a target yaw rate calculation unit that calculates a target yaw rate based on a vehicle speed, a steering angle, and the like. When the deviation between the actual yaw rate detected by the yaw rate sensor and the calculated target yaw rate is greater than or equal to a predetermined value, it is determined that the vehicle behavior is in an oversteer tendency or an understeer tendency, and actual control is performed by brake hydraulic pressure control for each wheel. The yaw rate is controlled to converge to the target yaw rate.

  As described above, when a vehicle equipped with both an active steering system and an active brake system is configured, after detecting an abnormality in the active steering system, the rear wheel steering angle is fixed as shown in the prior art, the following is shown: There was a problem.

  For example, when the driver tries to travel straight in a state where the rear wheel steering angle is generated due to an abnormality in the active steering system, the steering angle is generated by the correction steering. If the yaw rate is not generated even though the steering angle is generated, the active brake system may malfunction or the sensor may be erroneously diagnosed. Therefore, in order to avoid malfunction of the active brake system, if the active brake system is also shut off whenever the active steering system is abnormal, the robustness of the vehicle system may be reduced.

  The present invention has been made paying attention to the above problems, and the object of the present invention is to provide a vehicle control system and vehicle control capable of ensuring system robustness in a vehicle equipped with a plurality of systems for controlling vehicle behavior. It is to provide a method.

  To achieve the above object, according to the present invention, a steering angle sensor for detecting a steering angle of a driver, and an auxiliary steering angle for front wheels and / or rear wheels so as to obtain desired vehicle behavior characteristics based on the steering angle. Active steering means to be applied, vehicle behavior state quantity detection means for detecting a vehicle behavior state quantity, and braking force of four wheels so as to obtain a desired vehicle behavior characteristic based on the steering angle and the vehicle behavior state quantity In the vehicle control system comprising active brake means for controlling each of them, an abnormality detection means for detecting an abnormality of the active steering means, and when an abnormality is detected by the abnormality detection means, the auxiliary steering angle is made neutral. And a first stop means for returning and stopping the active steering means and continuing the active brake means.

  Therefore, when the active steer means is abnormal, the active steer means is returned to neutral and stops, so it is possible to eliminate malfunctions and misdiagnosis even if the active brake means is continued. Safety can be ensured while improving.

  Hereinafter, the best mode for realizing a vehicle control system of the present invention will be described based on an embodiment shown in the drawings.

[Configuration of vehicle control system]
FIG. 1 is a system configuration diagram illustrating a vehicle control system according to the first embodiment. The vehicle according to the first embodiment controls an engine controller (hereinafter referred to as ECU) 1 that controls an engine, an automatic transmission controller (hereinafter referred to as ATCU) 2 that controls an automatic transmission, and various meters. Meter controller (hereinafter referred to as MCU) 3, steering angle sensor 7 for detecting the steering angle of the driver, and integrated sensor 8 for detecting state quantities (yaw rate, lateral acceleration, longitudinal acceleration, etc.) related to the behavior of the vehicle. Is installed.

  The steering angle sensor 7 is provided with a controller 7a that outputs an electrical signal detected according to a change in angle as an angle signal, and a value obtained by removing a noise component or the like is output every predetermined period (for example, every 10 msec). . Further, the integrated sensor 8 is provided with a controller 8a for outputting an electric signal detected according to a change in the behavior of the vehicle as a yaw rate signal, a lateral acceleration signal, and a longitudinal acceleration signal, and a value obtained by removing noise components and the like. It is output every predetermined period (for example, every 5 msec).

  In addition, a front wheel steering unit 40 capable of adding / subtracting the steering angle of the front wheels 4a with respect to the steering angle of the driver, a rear wheel steering unit 50 capable of controlling the steering angle of the rear wheels 5a, and the wheels 4a, 5a. A brake unit 60 that can independently control the braking force according to the traveling state is mounted.

  The front wheel steering unit 40 includes a front wheel controller 4 and a front wheel actuator 41 that operates based on a command from the front wheel controller 4, and is disposed below an instrument panel in front of the vehicle. The rear wheel steering unit 50 includes a rear wheel controller 5 and a rear wheel actuator 51 that operates based on a command from the rear wheel controller 5, and is disposed in the vicinity of the rear wheel behind the vehicle. The brake unit 60 includes a brake controller 6 and a brake actuator 61 that operates based on a command from the brake controller 6, and is disposed in the engine room.

  The ECU 1, the ATCU 2, the MCU 3, the steering angle sensor 7, the brake controller 6, and the rear wheel controller 5 are provided with a low speed communication control port and are connected by a low speed CAN communication line 100. The communication speed of the low-speed CAN communication line 100 is configured so that data output from each controller can be transmitted and received every 10 msec.

  In CAN communication, a combination of a high signal and a low signal is output to two communication lines, and a bit signal is transmitted / received based on a deviation between these signals. Therefore, even if a signal is disturbed due to a disturbance or the like, a disturbance occurs simultaneously on the two communication lines. Therefore, a stable bit signal can be transmitted and received by taking a deviation. Further, in this communication line, sensor signals and the like output from each controller are output at a constant cycle or every time an event occurs, and only a necessary controller receives necessary information.

  The front wheel controller 4, the rear wheel controller 5, the brake controller 6, and the integrated sensor 8 are provided with a high-speed communication control port and are connected by a high-speed CAN communication line 200. The communication speed of the high-speed CAN communication line 200 is configured so that data output from each controller can be transmitted and received every 1 msec. In communication via the low-speed CAN communication line 100, the amount of data that can be transmitted / received within a unit time is small, and in communication via the high-speed CAN communication line 200, the amount of data that can be transmitted / received within a unit time is large. .

  As described above, the brake controller 6 and the rear wheel controller 5 are provided with both a high-speed communication control port and a low-speed communication control port, and are connected to both the high-speed CAN communication line 200 and the low-speed CAN communication line 100. Yes.

[4-wheel active steering system]
FIG. 2 is a system diagram showing a configuration of a four-wheel active steering system. The theory that the vehicle of the first embodiment is optimal to achieve such yaw rate and lateral acceleration as steering feeling and vehicle behavior characteristics when a driver generates a certain steering angle at a certain vehicle speed. Based on this, a four-wheel active steering system is provided in which auxiliary steering angles are given to the front and rear wheels. In other words, the feedback control system using a yaw rate sensor, a lateral acceleration sensor, or the like does not reflect the driver's steering intention, but starts control based on the actually generated vehicle behavior. It is not possible to obtain the optimal vehicle behavior characteristics according to the steering intention. Therefore, before and after the vehicle behavior is generated by feedforward control with respect to the steering angle and the vehicle speed, the front and rear wheel auxiliary steering angles are set to ensure a quick response.

(Configuration of front wheel steering unit)
The front wheel actuator 41 is provided on a steering shaft between the steering wheel and the rack and pinion mechanism. The steering shaft is composed of a first steering shaft connected to the steering wheel and a second steering shaft connected to the pinion, and the rotation of the second steering shaft with respect to the rotation angle of the first steering shaft is driven by the front wheel side motor 42. The angle is controlled so that it can be added or subtracted. The front wheel actuator is a well-known technique and will not be described.

  The front wheel side motor 42 is provided with a front wheel side rotation angle sensor 43 that detects the rotation angle of the front wheel side motor 42 and is output to the front wheel controller 4. In the front wheel controller 4, a calculation unit 401 that calculates the drive amount of the front wheel side motor 42 with respect to the target steering angle, and a servo that performs feedback control of the control amount of the front wheel side motor 42 based on the detection value of the front wheel side rotation angle sensor 43. A control unit 402 and a front wheel side driver unit 403 that outputs a current value to the front wheel side motor 42 are provided.

(Configuration of rear wheel steering unit)
The rear wheel actuator 51 is provided between the left and right rear wheels 5a. The left and right rear wheels 5a are connected by a parallel link. When one side of this link is moved in the vehicle width direction by the rear wheel side motor 51, a steering angle is generated in the rear wheel 5a due to elastic deformation of the parallel link. Since this rear wheel actuator is a well-known technique, description thereof is omitted.

  The rear wheel side motor 52 is provided with a rear wheel side rotation angle sensor 53 that detects the rotation angle of the rear wheel side motor 52 and is output to the rear wheel controller 5. In the rear wheel controller 5, a calculation unit 501 that calculates the driving amount of the rear wheel side motor 52 with respect to the target steering angle, and the control amount of the rear wheel side motor 52 are based on the detection value of the rear wheel side rotation angle sensor 53. A servo control unit 502 that performs feedback control, a rear wheel driver unit 503 that outputs a current value to the rear wheel motor 52, and a target rudder for front and rear wheels based on the steering angle and vehicle speed detected by the steering angle sensor 7. A target value calculation unit 504 that calculates a corner is provided. The front wheel controller 4 controls the front wheel side motor 42 based on the target steering angle of the front wheels.

(4-wheel active steering control configuration)
The rear wheel controller 5 connected to the low-speed CAN communication line 100 receives the steering angle information from the steering angle sensor 7 connected to the low-speed CAN communication line 100 and the vehicle speed information from the ATCU 2 connected to the low-speed CAN communication line 100. The target value calculation unit 504 calculates a target front wheel steering angle and a target rear wheel steering angle based on these two values. The target front wheel steering angle is output from the rear wheel controller 5 to the front wheel controller 4 via the high-speed CAN communication line 200. As described above, since the target front wheel steering angle and the target rear wheel steering angle are limited to the communication speed of the low-speed CAN communication line 100, they are calculated every 10 msec.

  The front wheel controller 4 drives the front wheel side motor 42 so that the received target front wheel steering angle is obtained. At this time, the servo control unit 402 and the front wheel side driver 403 calculate the control amount every 1 msec based on the detection value of the front wheel side motor rotation angle sensor 43 and the value of the current sensor and the like, and the front wheel side motor 42 is calculated every 200 μsec. Output. Such processing is executed by multitask processing or the like, and is appropriately assigned according to the processing capability of the CPU.

  The rear wheel controller 5 drives the rear wheel motor 52 so as to achieve the calculated target rear wheel steering angle. At this time, the servo control unit 502 and the rear wheel side driver 503 calculate the control amount every 1 msec based on the detection value of the rear wheel side motor rotation angle sensor 53 and the value of the current sensor, etc. Output to the motor 52.

  The auxiliary steering angles of the front wheels 4a and the rear wheels 5a are controls for directly changing the direction of the tire, in other words, the lateral force mainly of the tire force generated between the tire and the road surface is directly controlled by the actuator. It will be. At this time, if a failure or the like occurs in each actuator, there is a risk of directly affecting the behavior of the vehicle (particularly the turning state), so it is necessary to always perform a fail check. Therefore, the front wheel controller 4 transmits / receives rear wheel-side fail-related information (for example, an actuator signal) via the high-speed CAN communication line 200 a plurality of times until the target value calculation unit 504 calculates a new target value. Always monitor while. Similarly, the rear wheel controller 5 transmits / receives front wheel-side fail-related information (for example, an actuator signal or the like) a plurality of times via the high-speed CAN communication line 200 until a new target value is calculated by the target value calculation unit 504. Always monitor during.

[ABS / TCS / VDC control system]
FIG. 3 is a system diagram showing the configuration of the ABS / TCS / VDC control system. In the vehicle of the first embodiment, the slip state between the tire and the road surface is monitored, and the braking force is mainly controlled among the tire forces so as to obtain the highest braking force during braking (avoids locking of wheels). ABS control to be performed, TCS control to be able to transmit torque to the road surface most efficiently when driving force is output at the time of starting, etc. (so as not to slip beyond a predetermined slip ratio), and during turning An ABS / TCS / VDC control system that performs VDC control to suppress oversteer and understeer and to control the vehicle so as to obtain the desired vehicle behavior (by giving independent braking force to each wheel) is installed.

  Connected to the brake actuator 61 are a master cylinder 62 that generates brake fluid pressure by a driver's brake pedal operation, and a wheel cylinder 63 that generates braking force on each wheel. A wheel speed sensor 64 that detects the rotational speed of each wheel and a pressure sensor 62a that detects the master cylinder pressure are provided. In the brake actuator 61, a shut-off valve that shuts off the master cylinder 62 and the wheel cylinder 63, a pressure reducing valve that can reduce the hydraulic pressure in the wheel cylinder 63, and a hydraulic pressure in the wheel cylinder 63 are supplied to the driver. A pump or the like that can increase the pressure regardless of the intention is built in, and the braking force of each wheel can be controlled.

  The engine is provided with an electronic control injector 11 for controlling the fuel injection amount of the engine and an electronic control throttle 12 for controlling the throttle opening based on the command signal of the ECU 1 and controls the output torque of the engine as required. It is configured to be possible.

(About ABS control)
When the brake controller 6 detects the tendency of the wheel to lock, the wheel cylinder pressure that tends to lock is repeatedly increased and decreased, and the maximum braking force is secured by the optimum slip ratio.

(About TCS control)
When wheel drive slip is detected in the brake controller 6, a torque down command is output so as to reduce the output of the excessive engine, and fuel injection amount control and throttle opening control are performed to reduce the wheel drive slip. To prevent. Note that the wheel cylinder pressure of the drive wheel may be increased to prevent the slip, or the drive slip may be avoided by outputting an upshift command to the ATCU 2, which is not particularly limited.

(About VDC control)
The ABS control and the TCS control are controls that control the behavior of the vehicle in the front-rear direction, and the VDC control is a control in the left-right direction (turning state) of the vehicle. When the driver performs steering at a certain vehicle speed, load movement and yaw rate are generated accordingly. At this time, since the limit value of the cornering force of the tire is estimated in advance, a target yaw rate that does not exceed the limit value is calculated. The actual yaw rate detected by the integrated sensor 8 is compared with the target yaw rate. If the actual yaw rate exceeds the target yaw rate, an oversteer tendency occurs, and it is determined that an excessive yaw rate has occurred. A braking force is generated on the outer turning wheel and / or the rear turning inner wheel. On the other hand, if the actual yaw rate is smaller than the target yaw rate, an understeer tendency tends to occur, and it is determined that sufficient yaw rate has not occurred. Is generated. That is, the vehicle behavior is controlled by yaw rate feedback control.

  In the ABS / TCS / VDC control system, each sensor value is subjected to a fail check by logical monitoring with other sensor values. Here, the logic monitor compares, for example, the yaw rate value of the integrated sensor 8 with the yaw rate theoretical value based on the vehicle speed and the steering angle, and monitors whether these values are consistent. Details will be described later.

  As described above, both the four-wheel active steering system and the VDC control system control the behavior (turning state) of the vehicle. As basic control sharing, the VDC control system is in charge of the vicinity of the tire friction limit, and the four-wheel active steering system is in charge of a region where the tire friction force is sufficiently secured.

(4-wheel active steer system stop processing when abnormal)
Next, stop processing when the four-wheel active steering system is abnormal will be described with reference to the flowchart of FIG.

[Failure determination of 4-wheel active steering system]
In step S1, abnormality determination of the four-wheel active steering system is performed. If no abnormality has occurred, the process proceeds to step S2, and normal control is executed. If an abnormality has occurred, the process proceeds to step S3. When an abnormality has occurred in the front wheel controller 4, a value corresponding to a neutral deviation caused by the stop of the front wheel side motor 42 is output from the front wheel controller 4 to the brake controller 6 as a steering angle offset value.

[Vehicle stability judgment (VDC control malfunction avoidance processing)]
In step S3, based on the front wheel steering angle at the time of abnormality (equivalent to the sum of the steering angle and the front wheel side motor rotation angle), the rear wheel steering angle (equivalent to the rear wheel side motor rotation angle), the vehicle speed, and the vehicle specifications, The skid angle β is calculated.
In step S4, it is determined whether or not the vehicle body side slip angle β is larger than a predetermined value β0 corresponding to the VDC operation start threshold value. If larger, the process proceeds to step S5. Otherwise, the process proceeds to step S7.

[VDC control operation ensuring process]
In step S5, the VDC is operated, and in step S6, it is determined whether or not the VDC operation is finished. When the VDC operation is finished, the process proceeds to step S11.

[Logic monitor misdiagnosis avoidance process]
In step S7, the yaw rate estimated value f * is calculated based on the vehicle speed, the steering angle δ, and the vehicle specifications.
In step S8, an estimated steering angle value Δ * is calculated based on the vehicle speed, actual yaw rate f, and vehicle specifications.
In step S9, whether or not the deviation Δf between the actual yaw rate f and the yaw rate estimated value f * is smaller than a predetermined value f0 determined to be abnormal by the VDC logic monitor, and the actual steering angle δ and the steering angle estimated value δ It is determined whether or not the deviation Δδ from * is smaller than a predetermined value δ0 determined to be abnormal by the VDC logic monitor. If each condition is satisfied, it is determined that there is no possibility of erroneous diagnosis as an abnormality, and the process proceeds to step S10. Otherwise, it is determined that there is a possibility of erroneous diagnosis as abnormality, and the process proceeds to step S11.

[4-wheel active steering system stop processing]
In step S10, the control by the rear wheel controller 5 is stopped and fixed at the rear wheel steering angle when an abnormality occurs.
In step S11, whether or not the rear wheel can be returned to neutral, that is, if only the front wheel system has an abnormality due to the monitoring status of the system signal and no abnormality has occurred in the rear wheel system, or due to a temperature rise of the motor, etc. Determine whether it is a temporary abnormality that temporarily stops control, or an abnormality that immediately stops control when the rear wheel cannot be returned to neutral.If the rear wheel can be returned to neutral, proceed to Steps S12 and S13, where the rear wheel is neutral. This control flow is finished by returning to step S2.
In step S14, the control by the rear wheel controller 5 is stopped, the rear wheel steering angle is fixed when an abnormality occurs, and the VDC is shut off.

(Operation of abnormal stop processing)
Next, the operation of the abnormal stop process based on the flowchart will be described.
[Abnormality judgment of 4-wheel active steering system]
When an abnormality has occurred in the front wheel controller 4, the front wheel side motor rotation angle is output from the front wheel controller 4 to the brake controller 6 as a steering angle offset value. That is, when an abnormality occurs in the front wheel controller 4, a neutral shift due to the front wheel motor 42 stopping occurs. When the steering wheel is steered, the driver recognizes the state in front of the vehicle by visual observation and performs steering based on the visual observation. Therefore, even if an offset value is generated in the steering angle, the driver can appropriately correct the steering ( (No unnecessary side slip angle). Therefore, if the offset value of the steering angle is recognized in the VDC control, no malfunction or erroneous diagnosis is caused. On the other hand, when an abnormality has occurred in the rear wheel controller 5, there is a possibility that the auxiliary steering angle of the rear wheel cannot be returned to neutral. In this case, various determinations as to whether the safety of the vehicle can be ensured will be described later. Run in

[About vehicle stability judgment]
When the rear wheel controller 5 is stopped with the rear wheel auxiliary rudder angle remaining, if the driver does not continue to give corrective steering, the vehicle behavior is caused by the occurrence of the rear wheel side slip angle based on the rear wheel auxiliary rudder angle. There is a possibility that it cannot be stabilized. If the rear wheel auxiliary rudder angle is small, even when the rear wheel controller 5 is stopped, the vehicle behavior is merely the same as that of a two-wheel steering vehicle, and there is no particular problem.

  Therefore, if an abnormality occurs in the four-wheel active steering system, whether the vehicle body side slip angle β based on the front and rear wheel auxiliary steering angles at the time of abnormality detection is larger than a predetermined side slip angle β0 corresponding to the VDC operation start threshold value. Judging. When the vehicle is smaller than the predetermined side slip angle β0, it can be determined that the vehicle is stable, and in that case, the VDC does not particularly malfunction. At this time, the process proceeds to a process for avoiding misdiagnosis by a logic monitor such as various sensors.

[VDC control operation ensuring process]
When it is larger than the predetermined side-slip angle β0, it can be determined that the stability of the vehicle is lowered, and in this case, it is a region where the VDC operates. As described above, the VDC control operates near the limit of the tire force, and it is necessary to ensure the operation reliably from the viewpoint of ensuring safety. Therefore, the VDC control is first activated, and the VDC control is continued until this operation is completed, that is, until the vehicle body side slip angle becomes smaller than the predetermined value β0.

[About logic monitor misdiagnosis avoidance processing]
In the logic monitor misdiagnosis avoidance process,
Condition 1) The yaw rate estimated value f * is calculated based on the value of the steering angle δ, and when the deviation Δf between the yaw rate estimated value f * and the actual yaw rate f is less than the predetermined value f0, it is determined that the value is normal (first logic) Equivalent to the monitor part).
Condition 2) An estimated steering angle value δ * is calculated based on the value of the actual yaw rate f, and when the deviation Δδ between the estimated steering angle value δ * and the actual steering angle δ is less than a predetermined value δ0, it is determined as normal ( Equivalent to the second logic monitor unit).
When these conditions 1 and 2 are established, the rear wheel auxiliary steering angle is fixed as it is, and there is no possibility that the logical monitor performed by the VDC control makes a false diagnosis even if the active steering control is stopped.

[4 wheel active steering system stop processing]
On the other hand, when any of the above conditions 1 and 2 is not satisfied, it is determined whether the rear wheel can be returned to neutral because there is a risk of erroneous diagnosis by the logic monitor. If it is not possible to return to the neutral position, it may lead to malfunction or misdiagnosis, so the auxiliary steering angle of the rear wheels is fixed, active steer control is stopped, VDC control is shut off, and operation is performed using warning lights, etc. Inform the person of the abnormality.

  When the auxiliary steering angle of the rear wheels can be returned to neutral, i.e., when only the front wheel system is abnormal and there is no abnormality in the rear wheel system, or when the control temporarily stops due to motor temperature rise, etc. In the case of an abnormality, the rear wheel is returned to neutral and control by the rear wheel controller 5 is stopped. As a result, it is possible to avoid VDC control malfunctions and diagnostics, and even if an abnormality occurs in the four-wheel active steering system, it is possible to avoid blocking VDC control. Moreover, safety can be ensured while improving the robustness of the vehicle system.

  Hereafter, it enumerates about the effect of a present Example.

  (1) When an abnormality in the four-wheel active steering system is detected, the auxiliary steering angle is returned to neutral, the active steering control is stopped, and the VDC control is continued. Therefore, safety can be ensured while improving the robustness of the vehicle system.

  (2) When an abnormality in the four-wheel active steering system is detected and the vehicle is determined to be stable based on the vehicle side slip angle, the auxiliary steering angle given by the active steering control is fixed. And VDC control was continued. Therefore, safety can be ensured even when the rear wheel auxiliary steering angle cannot be returned to neutral. In particular, the vehicle side slip angle calculation includes the front wheel side slip angle and the rear wheel side slip angle as parameters, so it is possible to take into account the state of the front and rear wheel rudder angles when an abnormality occurs, and to accurately determine vehicle stability. be able to.

  (3) Detect whether the detected abnormality is an abnormality that immediately stops the four-wheel active steering system or a temporary abnormality that temporarily stops. If an abnormality that stops immediately is detected, the active steering system and VDC control Both were decided to stop. Therefore, it is possible to quickly notify the driver of a state in which safety is not sufficiently ensured. Further, in the case of a temporary abnormality, by continuing the VDC control, the control of the active steering system can be restored again when the abnormality is resolved.

  (4) The vehicle stability judgment is that the vehicle is judged to be stable when the vehicle side skid angle β based on the auxiliary steering angle at the time of abnormality detection is smaller than a predetermined skid angle β0 corresponding to the operation start threshold of VDC control. did. Therefore, when it is determined that the stability of the vehicle has deteriorated in the state where an abnormality has occurred in the four-wheel active steering system, the VDC control operation is performed, and after the vehicle becomes stable, the active steering system is stopped. Therefore, safety can be ensured.

  (5) The yaw rate estimated value f * of the vehicle is calculated based on the steering angle δ, and when the deviation between the yaw rate estimated value f * and the actual yaw rate is greater than or equal to a predetermined value f0, it is determined that there is an abnormality. Therefore, it is possible to avoid erroneous diagnosis of sensors or the like in the logic monitor in VDC control.

  (6) The estimated steering angle value δ * is calculated based on the actual yaw rate f, and when the deviation Δδ between the estimated steering angle value δ * and the actual steering angle δ is greater than or equal to a predetermined value δ0, it is determined that there is an abnormality. . Therefore, it is possible to avoid erroneous diagnosis of sensors or the like in the logic monitor in VDC control.

  Next, Example 2 will be described. Since the basic configuration is the same as that of the first embodiment, only different points will be described. FIG. 5 is a flowchart showing stop processing when an abnormality occurs in the four-wheel active steering system according to the second embodiment. In Example 1, in Steps S7 to S9, the determination was made based on the yaw rate and the steering angle diagnosed by the logic monitor. On the other hand, the second embodiment is different in that determination is made based on the vehicle body side slip angle in step S81 and step S91.

  In step S81, the virtual vehicle body side slip angle β ′ is calculated based on the front wheel steering angle, the neutral rear wheel auxiliary steering angle (δ = 0), the vehicle speed, and the vehicle specifications.

  In step S91, it is determined whether or not the deviation Δβ between the vehicle body side slip angle β calculated in step S3 and the virtual vehicle body side slip angle β ′ is larger than a predetermined value Δβ1. Otherwise, the process proceeds to step S10 (corresponding to the third logic monitor unit) since there is no possibility of causing a misdiagnosis.

  That is, when logical monitoring is performed in VDC control, the cause of erroneous diagnosis is due to the influence of the rear wheel auxiliary steering angle. Therefore, a large deviation between the vehicle side slip angle β at the time of occurrence of the abnormality and the virtual vehicle side slip angle β ′ when the rear wheel auxiliary rudder angle is returned to neutral can be erroneously diagnosed by the influence of the rear wheel auxiliary rudder angle. The situation becomes high. In this way, by avoiding misdiagnosis based on the side slip angle of the vehicle body, it is possible to avoid misdiagnosis of the entire parameters without calculating individual parameter conditions.

1 is a system configuration diagram illustrating a vehicle control system in Embodiment 1. FIG. 1 is a system diagram illustrating a configuration of a four-wheel active steering system in Embodiment 1. FIG. It is a system diagram showing the structure of the ABS / TCS / VDC control system in Example 1. 3 is a flowchart illustrating stop processing when an abnormality occurs in the four-wheel active steering system according to the first embodiment. 6 is a flowchart illustrating stop processing when an abnormality occurs in the four-wheel active steering system according to the second embodiment.

Explanation of symbols

1 Engine controller (ECU)
2 Automatic transmission controller (ATCU)
3 Meter controller (MCU)
4a Front wheel 4 Front wheel controller 5a Rear wheel 5 Rear wheel controller 6 Brake controller 7 Steering angle sensor 8 Integrated sensor 9 Brake controller 40 Front wheel steering unit 50 Rear wheel steering unit 60 Brake unit
100 Low-speed CAN communication line
200 High-speed CAN communication line

Claims (8)

A steering angle sensor for detecting the steering angle of the driver;
Active steering means for providing an auxiliary steering angle to the front wheels and / or the rear wheels so as to obtain a desired vehicle behavior characteristic based on the steering angle;
Vehicle behavior state quantity detection means for detecting a vehicle behavior state quantity;
Active braking means for controlling the braking force of each of the four wheels so as to obtain a desired vehicle behavior characteristic based on the steering angle and the vehicle behavior state quantity;
In a vehicle control system comprising:
An abnormality detection means for detecting an abnormality of the active steering means;
When an abnormality is detected by the abnormality detection means, a first stop means for returning the auxiliary steering angle to neutral, stopping the active steering means, and continuing the active brake means;
A vehicle control system comprising: The vehicle control system according to claim 1,
Vehicle stability determination means for determining whether the vehicle is stable;
When an abnormality is detected by the abnormality detection means and the vehicle is determined to be stable by the vehicle stability determination means, the auxiliary steering angle given by the active steering means is fixed and stopped, and the active brake Second stop means for continuing the means;
A vehicle control system comprising: The vehicle control system according to claim 1 or 2,
The abnormality detection means is means for detecting whether the detected abnormality is an abnormality that immediately stops the active steering means or a temporary abnormality that temporarily stops,
The first stop means is executed when a temporary abnormality is detected by the abnormality detection means, and a third stop means is provided for stopping both the active steering means and the active brake means when an abnormality that stops immediately is detected. A vehicle control system characterized by that. The vehicle control system according to any one of claims 2 to 3,
The vehicle stability determination unit determines that the vehicle is stable when a vehicle side skid angle based on an auxiliary steering angle at the time of detecting an abnormality is smaller than a predetermined skid angle corresponding to an operation start threshold value of an active brake means. Vehicle control system. The vehicle control system according to any one of claims 1 to 4,
The abnormality detection means calculates a state quantity estimated value of the vehicle behavior based on the value of the steering angle sensor, and the vehicle behavior state quantity estimated value and the vehicle behavior state quantity detected by the vehicle behavior state quantity detection means A vehicle control system comprising a first logic monitor unit that determines that an abnormality is detected when the deviation of the vehicle is greater than or equal to a predetermined value. The vehicle control system according to any one of claims 1 to 5,
The abnormality detection means calculates a steering angle estimated value based on the value of the vehicle behavior state quantity detection means, and a deviation between the steering angle estimated value and the steering angle detected by the steering angle sensor is not less than a predetermined value. A vehicle control system comprising a second logic monitor unit that determines that an abnormality occurs. The vehicle control system according to any one of claims 1 to 6,
The abnormality detection means calculates a deviation between a vehicle body side slip angle based on the auxiliary steering angle at the time of abnormality detection and a virtual vehicle body side slip angle when the auxiliary steering angle is neutral, and if this deviation is equal to or greater than a predetermined value, the abnormality is detected. A vehicle control system comprising a third logic monitor for determining. Active steer means for providing an auxiliary steering angle to the front wheels and / or rear wheels so as to obtain a desired vehicle behavior characteristic based on the steering angle, and a desired vehicle behavior characteristic based on the steering angle and the vehicle behavior state quantity And an active brake means for controlling the braking force of the four wheels.
A vehicle control method comprising: when an abnormality of the active steering means is detected, returning the auxiliary steering angle to neutral, stopping the active steering means, and continuing the active braking means.

Images