JP2007106210A - Behavior control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a behavior control device for a vehicle capable of performing an appropriate zero point correction in the behavior control device for the vehicle enabling the zero point correction of yaw rate sensors during travel and stop respectively. <P>SOLUTION: When a yaw rate correction value (YR0) calculating condition during travel is effected during travel of a vehicle, a yaw rate correction value YR0M during travel is determined (steps S11, 12), and when the yaw rate correction value (YR0) calculating condition during stop is effected during stop, the yaw rate correction value YR0S during stop is determined (steps S15, 17). When the counter value CT indicating the elapsed time from the nearest YR0M correction point exceeds a predetermined threshold Thx, YR0M is replaced (steps S18, 19) by YR0S. When the absolute value Ydiff of the difference between YR0M and YR0S exceeds the threshold A, a control threshold of the vehicle behavior control (step S26) is augmented (steps S23, 24). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle behavior control device that controls vehicle behavior using at least a yaw rate among vehicle state quantities, and more particularly to correction of a yaw rate sensor in the behavior control device.

  Of the vehicle state quantities, the yaw rate represents the rotational speed of the vehicle in the left-right direction, and is used as a state quantity for performing behavior control during turning. The output of the yaw rate sensor used for yaw rate measurement varies depending on the ambient temperature change or aging change. Therefore, a method for correcting the zero point using the output of the stopped yaw rate sensor is known.

Patent Document 1 is a technique for reliably performing such zero point correction during stoppage, and by differentiating the output value of the yaw rate sensor during a period in which the vehicle is substantially stopped, the differential value is obtained. By detecting the rotation of the vehicle based on this, when the vehicle is rotating on a turntable, for example, the zero point correction of the yaw rate is not performed, so that the zero point correction is surely performed. It is said.
Japanese Patent Laid-Open No. 11-148828

  However, with this device, zero point correction can be performed only when the vehicle is stopped, and therefore there is a problem that zero point correction cannot be performed when the vehicle is running continuously for a long time. Therefore, it is conceivable to appropriately perform zero point correction even during traveling. In that case, the problem is how to set the relationship between the zero point correction at the time of stopping and the zero point correction during traveling, such as when the vehicle is stopped after performing the zero point correction during traveling.

  In view of such a problem, the present invention provides a vehicle behavior control device capable of correcting a zero point of a yaw rate sensor during traveling and stopping, respectively. It is an object to provide a behavior control device.

  In order to solve the above-described problems, a vehicle behavior control apparatus according to the present invention is a vehicle behavior control apparatus that controls the behavior of a vehicle using at least the detection result of the yaw rate sensor. And a zero point correction unit that calculates a second correction value that is a correction value of the zero point output of the yaw rate sensor while the vehicle is traveling. When the difference between the first correction value and the second correction value is large, the control threshold value changing means for increasing the control start threshold value of the behavior control as compared with the small correction value, and the latest second correction value And zero point correction value changing means for causing the second correction value to coincide with the first correction value when a predetermined time has elapsed since the vehicle was acquired and the vehicle is stopped.

  The zero point correction during traveling is less accurate than the zero point correction during stopping. Therefore, if the difference between the zero point correction value during travel (second correction value) and the zero point correction value during stop (first correction value) is large, the control start threshold value after zero point correction is increased. This suppresses erroneous start of control when the accuracy of zero point correction is low. On the other hand, when a sufficient time has elapsed since the zero point correction during traveling and the vehicle is stopped, the second correction value is rewritten with the first correction value at that time (the second correction value is changed to the first correction value). The control start threshold value is reset.

  According to the present invention, since the zero point correction during traveling and the zero point correction during stoppage can be appropriately combined, even when the zero point of the yaw rate sensor fluctuates due to changes in the surrounding environment during traveling, the The fluctuation can be appropriately corrected. For this reason, the accuracy of the control of the vehicle behavior using the detection result of the yaw rate sensor is improved, and the stability is increased.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same reference numerals are given to the same components in the drawings as much as possible, and duplicate descriptions are omitted.

  FIG. 1 is a configuration diagram showing an embodiment of a vehicle behavior control apparatus according to the present invention. The present embodiment is a VSC (Vehicle Stability Control) system that stabilizes vehicle behavior during turning by controlling braking force and driving force using vehicle state quantities including a yaw rate.

The brake system includes disc brakes 10 _FL to 10 _RR provided on the wheels FL, FR, RL, and RR, and a brake actuator 11 that independently adjusts the hydraulic pressure supplied to the wheel cylinders of the disc brakes 10 _FL to 10 _RR , A brake pedal 12 for inputting the brake operation amount by the driver, a brake booster 13 for multiplying the operation amount of the brake pedal 12 by the driver, a master cylinder 14 for transmitting the multiplied brake depression force to the brake actuator 11, and a master cylinder 14 and a master cylinder pressure sensor 15 for detecting the hydraulic pressure.

Here, the brake actuator 11 is configured by combining, for example, a solenoid valve that switches connection of a hydraulic circuit, a pump that increases hydraulic pressure, and an accumulator, and each disk brake 10 is controlled by controlling the operation of each valve and pump. _The hydraulic pressure supplied to the wheel cylinders of _FL to 10 _RR can be adjusted independently.

  On the other hand, the drive system includes a throttle actuator 31 for driving a throttle (not shown) as well as an engine (not shown), a throttle opening sensor 32 for detecting the throttle opening, and an engine ECU 30 for controlling the driving of the engine. Prepare. The engine ECU 30 includes a CPU, a ROM, a RAM, and the like. In addition to the output of the throttle opening sensor 32, the engine ECU 30 receives outputs from an engine speed sensor, a coolant temperature sensor, an accelerator opening sensor, and the like (not shown). It controls the operation of drive system equipment including the throttle actuator 31.

The entire VSC system is controlled by the VSC ECU 40. The VSC ECU 40 is also composed of a CPU, ROM, RAM, and the like, and is connected to the engine ECU 30 so as to be able to communicate with each other via an in-vehicle LAN or the like. In addition to the output of the master cylinder pressure sensor 15 described above, the VSC ECU 40 detects the yaw rate sensor 21 that detects the yaw rate acting on the vehicle, the acceleration sensor 22 that detects the longitudinal acceleration of the vehicle, and the steering amount of the steering wheel 23. The outputs of the steering angle sensor 24 and the wheel speed sensors 25 _{FL to} 25 _RR installed on the respective wheels are inputted, and the operation of the brake actuator 11 is controlled.

Here, VSC control in the present embodiment will be briefly described. The VSC ECU 40 calculates a target yaw rate based on the acceleration obtained from the acceleration sensor 22, the vehicle speed obtained from the wheel speed sensors 25 _{FL to} 25 _RR , and the steering angle obtained from the steering angle sensor 24, and is detected by the yaw rate sensor 21. Compare with actual yaw rate. When the actual yaw rate is smaller than the target yaw rate, the VSC ECU 40 determines that the vehicle may protrude outward from the target course, and instructs the engine ECU 30 to drive the throttle actuator 31 to throttle the throttle. While suppressing the output, the brake actuator 11 applies a braking force by the disc brakes 10 _FL to 10 _RR of the wheels _FL to _RR and decelerates to prevent deviation from the course. On the other hand, if the actual yaw rate is greater than the target yaw rate, the VSC ECU 40 determines that the vehicle may spin, and the brake actuator 11 causes the disc brake of the front outer wheel to turn (for example, the left front wheel if turning right). Spin is suppressed by applying a braking force to the disc brake 10 _FL ). Thereby, the vehicle behavior at the time of turning can be stabilized.

  In order to effectively control the vehicle behavior by the VSC control, it is necessary to accurately measure the yaw rate. As the yaw rate sensor 21, a gyro sensor, a sensor using distortion, or the like is used. The output of these sensors varies depending on temperature and aging. Unlike equipment used for installation, vehicles often move between environments with extreme differences, and output fluctuations are more likely to occur than when they are installed in installation equipment. When the yaw rate output fluctuates, the timing of the stabilization control is performed when the stabilization control is performed even though the stabilization control is not originally required or when the stabilization control is necessary. May be delayed. Therefore, it is necessary to correct the yaw rate output according to the environment.

  FIG. 2 is a flowchart showing the control process performed in the present embodiment, and this control process includes a zero point correction process of the yaw rate output. This control is repeatedly executed at a predetermined timing by the VSC ECU 40 from when the power switch of the electrical equipment of the vehicle is turned on to when it is turned off.

  First, it is determined whether or not the engine is started (step S1). If the engine has not been started, it is not necessary to perform VSC control, so the processing is terminated. When the engine is started, the yaw rate value YR that is the output of the yaw rate sensor 21 is further read (step S2). Next, 1 is added to the time counter value T (step S3). The counter value T is reset to 0 when the power switch is turned on.

  In step S4, the current time counter value T is compared with a threshold value T1. This T1 is set to exceed the time required for the output of the yaw rate sensor 21 to stabilize after the power is turned on. When the time counter value T is equal to or less than T1, the initial value Yini is substituted for Ydiff (step S5), and the process proceeds to step S9 described later. Here, Yini is set to a value slightly larger than a constant A described later.

  On the other hand, if the time counter value T is larger than T1, the YR value read in step S2 is further added to YRA (step S6). Here, YRA is reset to 0 when the power switch is turned on. That is, YRA corresponds to an integrated value of yaw rate values YR after time counter value T1.

  In step S7, it is determined whether or not the current time counter value T is substantially equal to T1 + T2. Here, T2 is set as a time sufficiently longer than the fluctuation cycle when there is a temporal fluctuation in the output of the yaw rate sensor 21. When the time counter value T is substantially equal to T1 + T2, the value obtained by dividing Ydiff by YRA by T2, that is, the average value of the yaw rate value YR from the time T1 until the time counter value T increases from T1 to T2 is obtained. Set (step S8). After step S8 ends or when it is determined in step S7 that the time counter value T is not substantially equal to T1 + T2, the process proceeds to step S9, and 1 is added to the counter value CT. This counter value CT is also reset to 0 when the power switch is turned on.

  In subsequent step S10, it is determined whether or not the vehicle is stopped. Whether or not the vehicle is stopped may be determined based on the vehicle speed detected by the wheel speed sensor 25 being zero. Here, if it is determined that the vehicle is not stopped, the process further proceeds to step S11, and it is determined whether or not the yaw rate 0 point (YR0) calculation condition during traveling is satisfied. The YRO calculation condition during traveling is, for example, that the steering angle is within a predetermined range, the vehicle speed exceeds a predetermined value, the absolute value of the longitudinal acceleration of the vehicle is less than the predetermined value, and the YR value is within the predetermined range. Set as if there is. That is, it is estimated that the vehicle is traveling straight on a flat road at a constant speed. Note that the YR value is limited when the corrected zero point is extremely deviated from the original zero point, the failure of the yaw rate sensor 21 may be considered, and the one-way yaw rate after correction This is because the sensitivity may not be ensured.

  If it is determined in step S11 that the traveling YR0 calculation condition is satisfied, the process proceeds to step S12, and YR0M that is the YR0 value during traveling is obtained. This YR0M is preferably set as a time average value of the output value of the yaw rate sensor 21 during a predetermined time that satisfies the YR0 calculation condition during traveling. Further, if the zero point is suddenly changed, unstable control may be performed, and therefore it is preferable to limit the amount of change.

  After setting YR0M, 1 is set to FM, which is the running YR0 calculation flag, the counter value CT is reset to 0 (step S13), and the process proceeds to step S21 described later. If it is determined in step S11 that the traveling YR0 calculation condition is not satisfied, the process proceeds to step S14. In this case, YR0M retains the previous value and proceeds to step S21 described later.

  If it is determined in step S10 that the vehicle is stopped, the process proceeds to step S15, and it is determined whether or not the stopped YR0 calculation condition is satisfied. Here, the stopped YR0 calculation condition is set, for example, when the YR value is within a predetermined range. Here, the reason why the YR value is limited is based on the same reason as the YR0 calculation condition during traveling. Moreover, even when the vehicle is stopped, for example, a case where the vehicle is rotating on a turntable in a parking lot can be considered. The range of the YR value to be restricted may be the same as that during traveling, but may be different.

  If it is determined in step S15 that the stopped YR0 calculation condition is satisfied, the process proceeds to step S17, and YR0S that is the stopped YR0 value is obtained. This YR0S may be set as a time average value of the output value of the yaw rate sensor 21 during a predetermined time that satisfies the stop YR0 calculation condition and is similar to the above-described calculation of YR0M. After setting YR0S, the counter value CT is compared with the threshold value Thx (step S18). When CT exceeds the threshold value Thx, that is, when a long time (time when the counter value addition exceeds Thx) has elapsed since the most recent running YR0 point correction, the running YR0 point correction value YR0M is The YR0S obtained here is replaced (step S19). After replacement, or when CT is equal to or less than the threshold value Thx in step S18, the process proceeds to step S20, where 1 is set to FS that is the stopped YR0 calculation flag, and the process proceeds to step S21. And migrate. If it is determined in step S15 that the stopped YR0 calculation condition is not satisfied, the process proceeds to step S16. In this case, YR0S retains the previous value and proceeds to step S21.

  In step S21, it is determined whether or not at least one of FS and FM, which are YR0 calculation flags during stoppage and traveling, is set to 1. If either one is 1, the absolute value of the difference between YR0S, which is a stopped YR0 value, and YR0M, which is a running YR0 value, is set in Ydiff (step S22). After step S22 is completed and when both are determined to be 0 in step S21, the process proceeds to step S23 to determine whether or not Ydiff exceeds the threshold value A. If it is determined that Ydiff exceeds A, the process proceeds to step S24, where the VSC control threshold Th is set to be Th2 larger than the reference value Th1. If Ydiff is A or less, the VSC control threshold Th is set to the reference value Th1 (step S25). After setting the threshold Th, the VSC control process is performed (step S26), and the process is terminated. The yaw rate used in this VSC control is a value corrected with YR0M.

  Unlike when the vehicle is stopped, even when the driver intends to go straight, the actual yaw rate is not completely zero depending on the road surface condition and the driving condition. For this reason, the YR0 correction during traveling must be less accurate than the YR0 correction during stoppage. Therefore, in the present embodiment, instead of replacing the stopped YR0 correction value with the traveling YR0 correction value, the correction value is set independently, and when the difference is large, the behavior is smaller than when it is small. Unstable control is prevented by making it difficult to enter behavior control by setting a large threshold value for starting control.

  On the other hand, the vehicle continues running for a long time, and even when the zero point deviates from the YRO correction at the time of stopping after a long time has elapsed from the previous stop state, the zero point correction at the time of closer approach is performed by the zero point correction during traveling It is possible. In particular, control can be performed with high precision even when it is not appropriate to use the correction value obtained immediately before YR0S, for example, by traveling under a different environment.

  FIG. 3 is a graph showing a comparison of temporal changes in yaw rate, vehicle speed, Ydiff, and control threshold value Th in the control (Case 1) in this embodiment and another control method (Case 2). Here, Case 2 is a control method in which YR0M is set independently of YR0S, and corresponds to a control process in which Steps S18 and S19 are excluded from the control processes shown in FIG. That is, unless the YR0 calculation condition during traveling is satisfied, YR0M is not updated even when YR0 correction that is stopped midway is executed.

Here, the case where the traveling YR0 calculation condition is satisfied until time t ₀ , the vehicle is subsequently stopped from time t ₁ to t _2, and after traveling again, the traveling YR 0 calculation condition is satisfied again at time t _4. Suppose. Incidentally, t ₃ immediately after the start, the point at which the vehicle speed reaches a predetermined speed.

Case 1, even the case 2 cases, the period from time _{t 0} to time _{t 4,} YR0M operation condition is not satisfied. Therefore, in case 2, as shown by the broken line, α set at time t ₀ is maintained from time t ₀ to time t _4, and YR0M gradually decreases after time t ₄ , and time t ₆ can be matched to the current measured YR value. This is because the time variation of YR0M is limited. As a result, Ydiff until time t ₅ is not below A, the control threshold value Th becomes a state of being extended to a time t _5, hard state continues to enter the control. Moreover, since YR0M itself remains in a state deviated from the actual zero point between times t _{2 and} t ₆ , the accuracy of vehicle behavior control must be lowered.

In contrast, as in the case of Case 1 shown in heavy solid line, since the match between YR0M and YR0S at time t _3, is possible to perform control according to the latest zero point immediately after the start running It becomes possible. Here, rather than replace YR0S the YR0M at the time of the Thx elapsed from t ₀ to the counter value, the (specifically the time exceeds a predetermined vehicle speed) while the elapsed time after the start is performed replaced with This is to exclude the case where the vehicle itself is stopped without rotating the wheel, but the vehicle is rolling on the turntable, and the vehicle is expected to stop reliably. This is because correction is performed using the immediately preceding yaw rate value.

As the control threshold Th, Th1 that is not raised immediately after the start of traveling (time t ₃ ) can be used, so that the vehicle behavior particularly immediately after the start can be stably controlled. Further, since YR0M itself is replaced by YR0S having higher correction accuracy than the latest correction, a correction value close to the actual yaw rate can be obtained, and control accuracy is improved.

  In the control shown in FIG. 3, the control using both Th1 and Th2 as constants has been described as an example, but Th2 may be set larger as Ydiff is larger as shown in FIG. By changing the control threshold value steplessly or in multiple steps in this way, it is possible to finely set up the control threshold value to prevent unstable control, thereby preventing unstable control. It becomes possible to make active control compatible with as much as possible.

  Since the output fluctuation of the yaw rate sensor 21 is strongly influenced by the temperature fluctuation, a means for estimating the temperature in the vicinity of the installation position of the yaw rate sensor 21 is provided, and the temperature from the most recent running YR0 correction is included in the determination condition in step S18. It may be added that the change is larger than a predetermined change amount.

  If the CT is less than the threshold value Thx in the determination in step S18, the difference between YR0M and YR0S is compared with a predetermined value. If the CT is greater than the predetermined value, it is determined that the yaw rate sensor 21 is abnormal. You may make it do. In such a case, it means that the difference from the YR0 correction during stoppage is large despite the fact that the time has not elapsed since the most recent running YR0 correction time point. This is because any output is estimated to be abnormal rather than output fluctuation. In this case, it is preferable to raise the control threshold Th together.

  In the above description, the VSC control has been described as an example. However, the vehicle behavior control device according to the present invention is not limited to this, and can be suitably applied to various vehicle behavior control devices using a yaw rate.

It is a block diagram which shows one Embodiment of the vehicle behavior control apparatus which concerns on this invention. It is a flowchart which shows the control processing performed in this embodiment. It is a graph which compares and shows the time change of the yaw rate, vehicle speed, Ydiff, and control threshold value Th in the control in this embodiment and the control in the conventional embodiment. It is a graph which shows the example of a setting of variable Th2 of the control threshold value with respect to Ydiff.

Explanation of symbols

10 _FL -10 _RR ... disc brake, 11 ... brake actuator, 12 ... brake pedal, 13 ... brake booster, 14 ... master cylinder, 15 ... master cylinder pressure sensor, 21 ... yaw rate sensor, 22 ... acceleration sensor, 23 ... steering wheel , 24 ... Steering angle sensor, 25 _{FL to} 25 _RR ... Wheel speed sensor, 30 ... Engine ECU, 31 ... Throttle actuator, 32 ... Throttle opening sensor, 40 ... VSC ECU, _{FL to RR} ... Wheel.

Claims (1)

In a vehicle behavior control device that controls the behavior of a vehicle using at least the detection result of the yaw rate sensor,
A stopping zero point correction means for calculating a first correction value that is a correction value of the zero point output of the yaw rate sensor while the vehicle is stopped;
A running zero point correction means for calculating a second correction value that is a correction value of the zero point output of the yaw rate sensor during traveling of the vehicle;
A control threshold value changing means for increasing the control start threshold value of the behavior control as compared with a case where the difference between the first correction value and the second correction value is large;
Zero point correction value changing means for causing the second correction value to coincide with the first correction value when a predetermined time has elapsed since the acquisition of the latest second correction value and the vehicle is stopped. A vehicle behavior control device.

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