JP5271120B2 - Vehicle behavior control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle behavior control device capable of preventing abrupt change of a target control amount caused by a failure of a sensor or the like without causing a delay in behavior control. <P>SOLUTION: When the determination in step S22 is No, ATTS-ECU 16 determines whether drive force distribution base amount Db is a positive value or not in step S25; sets a value obtained by adding storage amount [D] of one cycle before to a rate determination threshold value Rth as target drive power distribution control amount Dtgt in step S26, if the determination is Yes; sets a value obtained by subtracting the rate determination threshold value Rth from the storage amount [D] of one cycle before as target drive power distribution control amount Dtgt in step S27, if the determination is No; then stores the target drive power distribution control amount Dtgt as the storage amount [D] in step S24; and returns to the start. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a vehicle behavior control device that suppresses a sudden change in a target control amount caused by a sensor failure or the like without causing a time delay in behavior control.

  VSA (Vehicle Stability Assist system), which is a vehicle behavior control device that improves the driving stability of automobiles, includes anti-lock breaking system (ABS) and Traction Control System (TCS), and a function to suppress skid during turning. Vehicle behavior stabilization control system (see Patent Document 1) and ATTS (Active Torque Transfer System: right and left driving force distribution device: patent) that continuously changes the driving force distribution between the left and right driving wheels to improve turning ability There are RTCs (Rear Toe Control system: refer to Patent Document 3) and the like that improve the steering stability during high-speed driving and reduce the turning radius when entering the garage. In these vehicle behavior control devices, for example, after setting the reference yaw rate based on the front wheel steering angle, the vehicle speed, the lateral acceleration, etc., the braking force of each wheel so that the actual yaw rate detected by the yaw rate sensor matches the reference yaw rate, The actuator is feedback-controlled by setting the driving force distribution between the left and right driving wheels and the control instruction value (target control amount) of the toe angle of the left and right rear wheels.

JP 2004-284485 A Patent No. 3340038 Japanese Patent Publication No. 5-33193

  In the vehicle behavior control device described above, for example, if the yaw rate sensor or the lateral acceleration sensor fails, the normative value of the yaw rate or yaw moment and the detected value are instantaneously deviated, and the vehicle behavior is not improved due to a sudden increase in the control instruction value. In addition to being stable, there is a possibility that the durability of the actuator may be reduced. Therefore, in many automobiles equipped with a vehicle behavior control device, a time limit amount of the control instruction value is limited to a predetermined range by incorporating a rate limiter in the control device. However, when the rate limiter is adopted, the amount of time change in the control instruction value decreases not only on the increase side but also on the decrease side, so that the detection value rapidly decreases during normal times (a state in which no sensor failure occurs). Even in this case, there is a problem that the control instruction value is difficult to decrease (that is, a time delay is caused in the behavior control) and the original performance of the apparatus cannot be exhibited.

  The present invention has been made in view of the above situation, and an object thereof is to provide a vehicle behavior control device that suppresses a sudden change in a target control amount caused by a sensor failure or the like without causing a time delay in behavior control. .

  The first invention includes a target motion state quantity setting means for setting a target motion state quantity of the vehicle, an actual motion state quantity detection means for detecting an actual motion state quantity of the vehicle, the target motion state quantity and the actual motion state. Control instruction base value setting means for setting a control instruction base value based on the amount, and target instruction value setting means for setting a target control instruction value by limiting a time change amount of the control instruction base value. The target instruction value setting means limits the amount of time change only when the absolute value of the control instruction base value increases.

  According to a second aspect of the present invention, in the vehicle behavior control device according to the first aspect of the invention, the target instruction value setting means, when the absolute value of the control instruction base value changes from increasing to decreasing, The control instruction value is held until it becomes equal to the control instruction base value.

  According to the present invention, even when the target vehicle behavior cannot be realized by behavior control, the control instruction value does not increase indefinitely, and a decrease in turning ability or the like is suppressed.

It is a top view which shows the apparatus structure of the vehicle which concerns on embodiment. It is a block diagram which shows schematic structure of ATTS-ECU which concerns on embodiment. It is a block diagram which shows schematic structure of the driving force distribution setting part which concerns on embodiment. It is a flowchart which shows the procedure of the driving force distribution control which concerns on embodiment. It is a flowchart which shows the procedure of the target driving force distribution setting process which concerns on embodiment. It is a graph which shows the relationship between a driving force distribution base amount and a target driving force distribution control amount.

  Hereinafter, two embodiments in which the present invention is applied to an FF (front engine / front drive) type four-wheeled vehicle (hereinafter simply referred to as an automobile) equipped with an ATTS will be described in detail with reference to the drawings.

[Embodiment]
FIG. 1 is a plan view showing a device configuration of an automobile according to the embodiment, FIG. 2 is a block diagram showing a schematic configuration of an ATTS-ECU according to the embodiment, and FIG. 3 is a target driving force distribution setting according to the embodiment. It is a block diagram which shows schematic structure of a part.

<< Configuration of Embodiment >>
<Vehicle device configuration>
First, an apparatus configuration of an automobile will be described with reference to FIG. In the description, for the four wheels and the members arranged corresponding thereto, subscripts indicating the front, rear, left and right are attached to the numerals of the numerals, for example, wheel 4fl (front left), wheel 4fr (front right), wheel 4rl ( Left rear) and wheels 4rr (right rear), and collectively referred to as wheels 4 for example.

  As shown in FIG. 1, an automobile 1 has four wheels 4 with tires 3 mounted on the front, rear, left and right of a vehicle body 2, and an EPS (Electric Power Steering) 11 that performs steering assist. The ATTS 13 that variably distributes the driving force to the left and right front wheels 4fl, 4fr (left and right drive shafts 5fl, 5fr) and the ATTS-ECU 16 (vehicle behavior control device) that controls the drive of the ATTS 13 are mounted.

  The vehicle 1 includes a wheel speed sensor 21 that detects the wheel speed for each wheel 4, a steering angle sensor 22 that detects the steering angle of the steering wheel 7, a yaw rate sensor 23 that detects the actual yaw rate of the vehicle body 2, and the vehicle body 2. A lateral G sensor 24 for detecting the lateral acceleration of the vehicle body 2, a longitudinal G sensor 25 for detecting the longitudinal acceleration of the vehicle body 2, a hydraulic sensor 26 for detecting the control hydraulic pressure of the ATTS 13, etc.

  The ATTS 13 is formed by a pair of planetary gear mechanisms, a hydraulic clutch, a hydraulic control valve that controls the driving of the hydraulic clutch, and the like, and distributes the driving force to the left and right front wheels 4fl and 4fr according to the driving current from the ATTS-ECU 16. Change continuously. The ATTS-ECU 16 includes a microcomputer, a ROM, a RAM, a peripheral circuit, an input / output interface, various drivers, and the like, and other various types are provided via a communication line (CAN (Controller Area Network) in this embodiment). It is connected to the control device, the ATTS 13, and the sensors 21 to 26.

<ATTS-ECU>
As shown in FIG. 2, the ATTS-ECU 16 includes an input / output interface (not shown), a vehicle speed estimation unit 41, an FF (feed forward) control unit 42, a reference vehicle model 43, an observer 44, a yaw rate FB (feedback). ) Setting unit 45, yaw moment FB setting unit 46, slip angle FB setting unit 47, FB control unit 48, distribution base amount setting unit 49, target driving force distribution setting unit 50, and target driving current generation unit 51.

  The vehicle speed estimation unit 41 estimates the vehicle speed of the automobile 1 based on the wheel speed of each wheel 4. The FF control unit 42 sets the driving force distribution FF control amount based on the steering angle and the vehicle speed. The reference vehicle model 43 sets a reference yaw rate, a reference yaw moment, and a reference slip angle based on the steering angle, the vehicle speed, and the like. The observer 44 calculates an estimated yaw moment and an estimated slip angle based on the vehicle speed, lateral acceleration, longitudinal acceleration, actual yaw rate, and control hydraulic pressure.

  The yaw rate FB setting unit 45 sets the yaw rate FB value based on the standard yaw rate and the actual yaw rate. The yaw moment FB setting unit 46 sets the yaw moment FB value based on the standard yaw moment and the estimated yaw moment. The slip angle FB setting unit 47 sets a slip angle FB value based on the reference slip angle and the estimated slip angle. The FB control unit 48 sets the driving force distribution FB control amount based on the yaw rate FB value, the yaw moment FB value, and the slip angle FB value.

  The distribution base amount setting unit 49 sets the driving force distribution base amount based on the driving force distribution FF control amount and the driving force distribution FB control amount. The target driving force distribution setting unit 50 sets the target driving force distribution based on the driving force distribution base amount. The target drive current generator 51 sets a target drive current based on the target drive force distribution and outputs it to the ATTS 13.

<Target driving force distribution setting section>
As shown in FIG. 3, the target driving force distribution setting unit 50 stores an increase / decrease determining unit 61, an increasing time processing unit 62, a decreasing time processing unit 63, a changeover switch 64, and a target driving force distribution control amount Dtgt. And a store unit 65 that stores the quantity [D].

  The increase / decrease determination unit 61 calculates the absolute value (base amount absolute value) | Db | of the driving force distribution base amount Db based on the difference between the current driving force distribution base amount Db and the driving force distribution base amount Db of the previous cycle. It is determined whether the state is an increase state or a decrease state. Further, when the base amount absolute value | Db | is in an increasing state, the increase time processing unit 62 sets the target driving force distribution control amount Dtgt according to the comparison result between the time change rate | ΔD | and the rate determination threshold value Rth. Set. In addition, when the base amount absolute value | Db | is in a decreasing state, the decrease-time processing unit 63 determines that the base amount absolute value | Db | and the absolute value of the store amount [D] one cycle before (store amount absolute value) | The target driving force distribution control amount Dtgt is set according to the comparison result with [D] |. The changeover switch 64 switches processing between the increase time processing unit 62 and the decrease time processing unit 63 according to the determination result of the increase / decrease determination unit 61. Note that the rate determination threshold value Rth is set to the largest value assumed in a normal state, and when the time change rate | ΔD | exceeds this value, it can be regarded as a failure of the sensors.

<< Operation of Embodiment >>
<Driving force distribution control>
When the automobile 1 starts running, the ATTS-ECU 16 repeatedly executes driving force distribution control whose procedure is shown in the flowchart of FIG. 4 at a predetermined control interval (for example, 10 ms).

  When the driving force distribution control is started, the ATTS-ECU 16 firstly controls the driving force distribution FF based on the vehicle speed and the steering angle in step S1 of FIG. 4 in order to realize quick driving force distribution according to the driver's steering. Set the amount Dff.

  Next, the ATTS-ECU 16 sets the yaw rate FB value YRfb according to the difference between the reference yaw rate and the estimated yaw rate in step S2, and in step S3, the yaw moment FB value according to the difference between the reference yaw moment and the estimated yaw moment. YMfb is set, and the slip angle FB value SAfb is set according to the difference between the standard slip angle and the estimated slip angle in step S4. Next, in step S5, the ATTS-ECU 16 sets the driving force distribution FB control amount Dfb by adding the yaw rate FB value YRfb, the yaw moment FB value YMfb, and the slip angle FB value SAfb.

  Next, the ATTS-ECU 16 sets a driving force distribution base amount Db in step S6 based on the sum of the driving force distribution FF control amount Dff and the driving force distribution FB control amount Dfb, and then in step S7, a target driving force described later. The target driving force distribution control amount Dtgt is set by the distribution setting process. Thereafter, the ATTS-ECU 16 sets / outputs a target drive current Itgt for the ATTS 13 (hydraulic control valve drive linear solenoid) in step S8.

<Target driving force distribution setting process>
The ATTS-ECU 16 executes a target driving force distribution setting process whose procedure is shown in the flowchart of FIG. 5 in step S7 of the driving force distribution control.
When the target driving force distribution setting process is started, the ATTS-ECU 16 determines whether or not the base amount absolute value | Db | is in an increasing state in step S21 in FIG. 5, and if this determination is Yes, step S22 is performed. To further determine whether or not the time change rate | ΔD | is smaller than the rate determination threshold value Rth. If the determination in step S22 is Yes, the ATTS-ECU 16 stores the driving force distribution base amount Db as it is in the target driving force distribution control amount Dtgt in step S23 and then stores the target driving force distribution control amount Dtgt in step S24. Store as quantity [D] and return to start.

  If the determination in step S22 is No, the ATTS-ECU 16 determines in step S25 whether or not the driving force distribution base amount Db is a positive value. If this determination is Yes, in step S26. A value obtained by adding the rate determination threshold Rth to the store amount [D] one cycle before is set as the target driving force distribution control amount Dtgt. If No, the rate determination threshold Rth is calculated from the store amount [D] one cycle before in step S27. After subtracting the target driving force distribution control amount Dtgt, the target driving force distribution control amount Dtgt is stored as the store amount [D] in step S24 and the process returns to the start.

  On the other hand, when the base amount absolute value | Db | shifts to a decreasing state and the determination in step S21 is No, the ATTS-ECU 16 determines that the base amount absolute value | Db | is the store amount absolute value | [D] | It is determined whether or not it is smaller. While this determination is No, the target driving force distribution control amount Dtgt is set to the store amount [D] in step S29, and then the target driving force distribution control amount Dtgt is stored in step S24. Store as [D] and return to start.

  When the base amount absolute value | Db | decreases and the determination in step S28 becomes Yes (when the base amount absolute value | Db | becomes smaller than the store amount absolute value | [D] |), the ATTS-ECU 16 In step S30, the driving force distribution base amount Db is directly used as the target driving force distribution control amount Dtgt. In step S24, the target driving force distribution control amount Dtgt is stored as the store amount [D], and the process returns to the start.

  In the present embodiment, by adopting such a configuration, as shown in FIG. 6, even if the base amount absolute value | Db | increases rapidly, the time rate of change of the target driving force distribution control amount Dtgt is the rate. It is limited to the determination threshold value Rth, and it is possible to prevent the vehicle behavior from becoming unstable and the actuator durability from being lowered. When the base amount absolute value | Db | is decreased, the target driving force distribution control amount Dtgt is constant until the base amount absolute value | Db | becomes equal to the store amount absolute value | [D] | After the value | Db | becomes equal to the store amount absolute value | [D] |, the target driving force distribution control amount Dtgt is quickly reduced. Therefore, the behavior control is performed unlike the conventional rate limiter. Time delay is less likely to occur.

  Although description of specific embodiment is finished above, the aspect of the present invention is not limited to the above embodiment. For example, although the above-described embodiment applies the present invention to the control of ATTS, it is naturally applicable to the control of VSA, RTC, and the like. In addition, the specific configuration of the vehicle, the specific procedure of the control, and the like can be changed as appropriate without departing from the spirit of the present invention.

1 Automobile (vehicle)
2 Body 4 Wheel 13 ATTS
16 ATTS-ECU (Vehicle Behavior Control Device)
23 Yaw rate sensor (actual motion state quantity detection means)
43 Reference vehicle model (target motion state quantity setting means)
46 Yaw moment FB setting section 61 FB base value setting section (control instruction base value setting means)
62 Yaw rate FB value setting unit (target instruction value setting means)

Claims (2)

A target motion state quantity setting means for setting a target motion state quantity of the vehicle;
An actual movement state quantity detecting means for detecting an actual movement state quantity of the vehicle;
Control instruction base value setting means for setting a control instruction base value based on the target movement state quantity and the actual movement state quantity;
Target instruction value setting means for setting a target control instruction value by limiting a time change amount of the control instruction base value;
The target instruction value setting means limits the amount of time change only when the absolute value of the control instruction base value increases.   When the absolute value of the control instruction base value changes from increasing to decreasing, the target instruction value setting means holds the target control instruction value at that time until it becomes equal to the control instruction base value. The vehicle behavior control apparatus according to claim 1.

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