JP5328471B2 - Vehicle stop determination device - Google Patents

Description

  The present invention relates to a vehicle stop determination device for determining stop of a vehicle such as an automobile.

  As a conventional vehicle stop determination device, for example, as described in Patent Document 1, a device including a vehicle stop determination unit that determines stop of a vehicle based on a vehicle state is known.

JP 2006-111208 A

  However, in the vehicle stop determination device as described above, the wheel may be locked in the vehicle speed range immediately before the vehicle stops, and there is a possibility that the stop of the vehicle is erroneously determined based on the wheel lock. In particular, on low-μ roads, wheels are likely to be locked in the vehicle speed range immediately before stopping, so this possibility becomes significant.

  Then, this invention makes it a subject to provide the vehicle stop determination apparatus which can determine the stop of a vehicle reliably.

  In order to achieve the above object, a vehicle stop determination device according to the present invention includes a vehicle stop determination means for determining stop of a vehicle, and a lock of a vehicle wheel after the vehicle speed becomes a predetermined speed or less. And a determination prohibiting means for prohibiting the determination by the vehicle stop determination means for a predetermined time as a possible period.

  In this vehicle stop determination device, after the vehicle speed becomes equal to or lower than the predetermined speed, it is prohibited to determine stop of the vehicle for a predetermined time as a period during which the wheels of the vehicle can be locked. Accordingly, it is possible to suppress erroneous determination of the wheel lock as the stop of the vehicle, and it is possible to reliably determine the stop of the vehicle.

  In addition, it is preferable that an ABS control unit that performs ABS control to suppress the lock of the wheel is provided, and the predetermined speed is a lower limit speed at which the ABS control unit can be operated. In the speed range where the ABS control means does not operate in the vehicle speed range immediately before the vehicle stops, since the wheel lock is not suppressed, it is particularly easy to erroneously determine the stop. Thus, the predetermined speed can be operated by the ABS control means. When the speed is the lower limit speed, the above-described effect for reliably determining the stop of the vehicle is particularly effective.

  Further, it is preferable that a lock state detection unit that detects a lock state of the wheel is provided, and the determination prohibiting unit calculates the predetermined time based on the lock state detected by the lock state detection unit. In this case, erroneous determination of the wheel lock as a vehicle stop can be suitably suppressed, and the vehicle stop can be reliably determined.

  At this time, the lock state detection means preferably detects the lock state based on an integrated value of a difference between the wheel speed of the wheel and the vehicle speed or a correlation value of the integrated value. In this case, it is possible to reliably grasp the locked state and prevent erroneous determination of the wheel lock as a vehicle stop, and it is possible to reliably determine the stop of the vehicle.

  Further, it is preferable that a braking amount detection unit for detecting the braking amount of the vehicle is provided, and the determination prohibiting unit calculates the predetermined time based on the braking amount detected by the braking amount detection unit. In this case, it is possible to reliably determine the stop of the vehicle at a timing according to the braking amount.

  At this time, the braking amount detection means may detect the braking operation amount of the driver of the vehicle as the braking amount.

  In addition, when there is a history of ABS control performed by the ABS control unit after the brake operation, it is preferable that determination by the vehicle stop determination unit and determination by the determination prohibition unit are prohibited. In this case, if there is a history of the ABS control, there is a high possibility that the wheel lock is erroneously determined as the stop of the vehicle. Can be judged reliably.

  Further, it is preferable that a lock state determination unit for determining a lock state of the wheel is provided, and the determination prohibiting unit corrects the predetermined time based on the lock state determined by the lock state determination unit. In this case, it is possible to reliably determine the stop of the vehicle at a timing according to the locked state.

  At this time, when the vehicle speed is equal to or lower than the constant vehicle speed, the lock state determination means adds the wheel lock value that is the difference between the wheel speed and the vehicle speed when the wheel speed of the wheel becomes smaller than the vehicle speed, and adds the wheel lock integrated value. And the lock state is determined according to the wheel lock integrated value, and the determination prohibiting unit may correct the predetermined time according to the wheel lock integrated value.

  Here, the lock state determination means calculates the wheel lock value of each wheel, and calculates only the wheel lock value of the wheel having the largest absolute value of the wheel lock value among the wheels to calculate the wheel lock integrated value. Is preferred. In this case, it is possible to accurately determine the locked state, and thus it is possible to reliably determine the stop of the vehicle at a timing that accurately corresponds to the locked state.

  According to the present invention, it is possible to reliably determine whether the vehicle has stopped.

It is a block diagram which shows the structure of the vehicle stop determination apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the process sequence of the vehicle stop determination apparatus of FIG. It is a graph for demonstrating the timer time set with the vehicle stop determination apparatus of FIG.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same or equivalent elements will be denoted by the same reference numerals, and redundant description will be omitted.

  As shown in FIG. 1, the vehicle stop determination device 1 of the present embodiment is for determining stop (hereinafter also referred to as “stop determination”) of a vehicle 10 such as an automobile braking on a low μ road, for example. It is mounted on the vehicle 10. The vehicle stop determination device 1 includes an ECU (Electronic Control Unit) 2 as a controller composed of, for example, a CPU, a ROM, and a RAM.

  A brake sensor 3, a wheel speed sensor 4, and an ABS (Antilock Brake System) control device 5 are connected to the ECU 2. The brake sensor 3 is for detecting a braking amount related to braking of the vehicle 10. Here, the brake sensor 3 detects a brake operation amount by the driver of the vehicle 10 and outputs it to the ECU 2. As the brake sensor 3, for example, a master pressure sensor is used. Note that the deceleration of the vehicle 10 may be detected as the braking amount.

  The wheel speed sensor 4 detects each wheel speed of each wheel of the vehicle 10 and outputs a pulse signal corresponding to the rotation speed of each wheel to the ECU 2. Here, a magnetoresistive element (MRE: Magneto Resistive Element) is used for the wheel speed sensor 4. The ABS control device 5 performs ABS control for suppressing wheel lock. Further, the ABS control device 5 outputs the operating state to the ECU 2.

  The ECU 2 determines stop (that is, stop) of the vehicle 10 to be braked, and performs such determination while the timer time elapses after the estimated vehicle speed (estimated vehicle body speed) estimated from the wheel speed reaches a predetermined speed. Prohibited (details will be described later).

  In the vehicle stop determination device 1 configured as described above, the ECU 2 executes the following process to determine the stop of the vehicle 10 when the vehicle 10 is braked. That is, first, the vehicle speed of the vehicle 10 is estimated as the estimated vehicle speed from each wheel speed detected by the wheel speed sensor 4. Subsequently, a wheel lock value is calculated based on the difference between each wheel speed and the estimated vehicle speed (S1).

  Specifically, for each wheel, “wheel speed−estimated vehicle speed”, which is the difference between the wheel speed and the estimated vehicle speed, is obtained, and the minimum value (that is, the absolute value having the maximum value) is selected. . When the selected value of “wheel speed−estimated vehicle speed” is negative (<0), this value is calculated as a wheel lock value, while when the value of “wheel speed−estimated vehicle speed” is positive (> 0) The wheel lock value is calculated as zero. The wheel lock value may be calculated based on the difference between the wheel deceleration and the vehicle body deceleration.

  Subsequently, when the estimated vehicle speed is equal to or lower than the set speed, the calculated wheel lock values are integrated to obtain a wheel lock integrated value representing the lock state of the wheels (S2 → S3). On the other hand, if the estimated vehicle speed is greater than the set speed, the wheel lock integrated value is reset (S2 → S4).

  Subsequently, it is determined whether or not the ABS control device 5 is operating, that is, whether or not the estimated vehicle speed has reached the lower limit speed at which the ABS control device 5 can operate (S5). When the ABS control device 5 is in operation, for example, by setting an operation history flag, “operation history exists” is set, and the process proceeds to S1 again (S6). When the ABS control device 5 is not operating, it is determined whether or not there is an operation history of the ABS control device 5 (S7).

  When there is an operation history of the ABS control device 5 (Yes in S7), a timer time (predetermined time) is set as a period during which the wheel can be locked (S8). Specifically, a timer time is temporarily set using the brake operation amount of the driver detected by the brake sensor 3, and the timer time is corrected by correcting the temporarily set timer time using the wheel lock integrated value. To decide.

  More specifically, the driver's brake operation amount detected by the brake sensor 3 at the end of the operation of the ABS control device 5 is made to correspond to a previously determined timer time map, and a temporarily set timer time is derived. At the same time, the wheel lock integrated value is made to correspond to the correction amount map obtained in advance to determine the road surface condition (that is, the wheel lock state) (bad road determination) and to derive the correction amount. Then, the correction amount is added to the temporarily set timer time to determine the timer time.

  FIG. 3 is a graph for explaining the timer time set by the vehicle stop determination device of FIG. 1, FIG. 3 (a) shows an example of the timer time map, and FIG. 3 (b) is a correction amount map. An example is shown. As shown in FIG. 3A, in the timer time map M1 here, the timer time is set so as to decrease linearly as the brake operation amount increases.

  As shown in FIG. 3B, in the correction amount map M2 here, the correction amount is set so as to increase as the wheel lock integrated value increases. Further, the correction amount map M2 is configured such that the inclination of increase of the correction amount changes when the wheel lock integrated value is the predetermined values P1 and P2. According to this correction amount map M2, when the wheel lock integrated value is a value up to a predetermined value P1, the road surface condition is judged as snow pressure, and when the wheel lock integrated value is a value between the predetermined values P1 and P2, the road surface condition is straddled. When the wheel lock integrated value is equal to or greater than the predetermined value P2, the road surface condition is determined to be ice.

  Subsequently, the timer count is started, and when the timer count value has passed the timer time, it is determined that the vehicle 10 has stopped (S9 to S11). Then, after that, the brake system (stop maintenance means) that controls and holds the brake pressure and maintains the stop state is actuated by using the stop determination as a trigger.

  On the other hand, when there is no operation history of the ABS control device 5 (No in S7), the timer count value is reset, and thereafter, when the pulse signal is not input from the wheel speed sensor 4 for a certain time, it is determined that the vehicle 10 has stopped. On the other hand, when the pulse signal is input from the wheel speed sensor 4 for a certain period of time, the process shifts to S1 again (S12, S13).

  As described above, in the vehicle stop determination device 1 of the present embodiment, when the ABS control is performed when the vehicle 10 is braked, the brake operation amount and the road surface state of the driver are detected when the ABS control is completed, and the timer Counting is started, and it is determined that the vehicle 10 has stopped when the timer count value has elapsed the timer time. That is, stop determination is prohibited for the timer time from the end of ABS control. Here, the timer time is made variable according to the brake operation amount and the road surface condition of the driver, the wheel lock value is detected at every control interval, and the wheel lock value is sequentially accumulated below the set speed, and the ABS control ends. The road surface condition is detected by using the integrated value at the time.

  By the way, normally, since ABS control is not performed in the constant vehicle speed range immediately before the stop, when the vehicle speed is in this constant vehicle speed range, the wheels are likely to be locked. Therefore, in the conventional vehicle stop determination device that performs the stop determination only by the absence of a pulse signal from the wheel speed sensor 4 for a certain period of time, even when the wheel is locked, the vehicle is still moving. It may be erroneously determined that the vehicle is stopped. As a result, the vehicle stop maintaining means is activated at an early stage, further promoting the lock of the wheels and making the vehicle behavior unstable.

  On the other hand, in the present embodiment, after the vehicle speed becomes equal to or lower than the lower limit speed at which the ABS control device 5 can operate, the timer time as a period during which the wheels of the vehicle 10 can be locked and stop determination are prohibited. It is possible to suppress erroneous determination that the wheel lock is the stop of the vehicle 10, and it is possible to reliably determine the stop of the vehicle 10. As a result, it is possible to appropriately activate the vehicle stop keeping means and stabilize the vehicle behavior.

  In the present embodiment, as described above, the vehicle stop determination is prohibited until the timer time calculated based on the brake operation amount elapses after the vehicle speed at which the ABS control does not operate. Therefore, the stop of the vehicle 10 can be reliably determined at a suitable timing according to the braking amount.

  In addition, since the amount that the vehicle 10 slips after the wheels are locked until the vehicle stops depends on the road surface condition and the road surface condition such as the type of the road surface, the timing for determining whether to stop depends on the road surface condition. In this respect, in the present embodiment, the timer time is corrected according to the road surface condition, so that the stop of the vehicle 10 can be reliably determined at an appropriate timing according to the road surface condition.

  In particular, since it is possible to determine changes in road surface conditions based on wheel lock integrated values obtained by sequentially integrating wheel lock values, it is possible to determine road surface conditions such as snow-capped roads, straddle roads, and icy roads. An accurate stop determination can be made accordingly.

  Note that if the road surface condition is determined using values based on fluctuations in the wheel speeds of all the wheels, the difference between the values may become minute between the road surface types in some cases, and the road surface type is accurately determined. It may be difficult to determine. On the other hand, in this embodiment, as described above, the road surface condition is determined using the wheel lock integrated value obtained by sequentially integrating the wheel lock value for one wheel at a set speed or less. The difference in the wheel lock integrated value is remarkable. Therefore, it is possible to accurately determine the road surface condition, and to reliably determine the stop of the vehicle 10 at a timing that accurately corresponds to the road surface condition.

  In the present embodiment, as described above, when there is an operation history of the ABS control device 5 after the brake operation (Yes in S7), stop determination is prohibited (S8 to S10) and stop determination (S11). Has been done. In this case, if there is a history of performing the ABS control, there is a high possibility that the wheel lock is erroneously determined to be the stop of the vehicle 10, and thus the above-described effect of suppressing such erroneous determination is suitably exhibited. It is possible to reliably determine 10 stops.

  As mentioned above, although preferred embodiment of this invention was described, the vehicle stop determination apparatus which concerns on this invention is not restricted to the said vehicle stop determination apparatus 1 which concerns on embodiment, The summary described in each claim was changed. It may be modified within the range not applied, or applied to other things.

  For example, in the above embodiment, it is determined that the vehicle 10 has stopped unconditionally after the timer time has elapsed from the end of the operation of the ABS control device 5, but when the predetermined condition is satisfied after the timer time has elapsed. It may be determined that the vehicle 10 has stopped. In short, the vehicle stop determination may be prohibited for a predetermined time after the vehicle speed becomes equal to or lower than the predetermined speed.

  In the above embodiment, the timer time is set using the wheel lock integrated value at the end of the operation of the ABS control device 5, but the timer time is set using the wheel lock integrated value at a time other than at the end of the ABS control operation. It may be set. Note that determining the locked state of the vehicle includes not only determining the road surface state as in the above embodiment, but also determining changes in the wear of wheels (tires).

  In the above, the ECU 2 constitutes a vehicle stop judgment means and a judgment prohibition means, the brake sensor 3 constitutes a braking amount detection means, the ECU 2, the brake sensor 3 and the wheel speed sensor 4 constitute a lock state judgment means, The ABS control device 5 constitutes an ABS control means, and the ECU 2 and the wheel speed sensor 4 constitute a lock state detection means.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle stop determination apparatus, 2 ... ECU (vehicle stop determination means, determination prohibition means, lock state determination means, lock state detection means), 3 ... Brake sensor (brake amount detection means, lock state determination means), 4 ... Wheel Speed sensor (lock state determination means, lock state detection means), 5 ... ABS control device (ABS control means), 10 ... vehicle.

Claims (9)

Vehicle stop determination means for determining stop of the vehicle;
A determination prohibiting means for prohibiting determination by the vehicle stop determination means for a predetermined time as a period during which the wheel of the vehicle may be locked after the vehicle speed of the vehicle becomes equal to or lower than a predetermined speed;
A lock state detection means for detecting the lock state of the wheel ,
The determination stop means calculates the predetermined time based on the lock state detected by the lock state detection means . ABS control means for performing ABS control to suppress the lock of the wheel,
2. The vehicle stop determination device according to claim 1, wherein the predetermined speed is a lower limit speed at which the ABS control means is operable. If there is a history of the ABS control is performed by the ABS control means after the brake operation, according to claim 2, characterized in that said vehicle stop determining means according to the determination and the determination prohibition means by said determination prohibition is performed Vehicle stop determination device. The lock state detection means detects the lock state based on an integrated value of a difference between a wheel speed of the wheel and the vehicle speed or a correlation value of the integrated value . The vehicle stop determination device according to one item . A braking amount detecting means for detecting the braking amount of the vehicle;
The vehicle stop determination device according to any one of claims 1 to 4, wherein the determination prohibiting unit calculates the predetermined time based on a braking amount detected by the braking amount detection unit.   6. The vehicle stop determination device according to claim 5, wherein the braking amount detection means detects a braking operation amount of a driver of the vehicle as the braking amount. A lock state determining means for determining a lock state of the wheel;
The determination prohibition means, the vehicle stop determination apparatus according to any one of claims 1-6, characterized in that to correct the predetermined time based on the lock state is determined by the locked state determining means. The lock state determination means integrates a wheel lock value that is a difference between the wheel speed and the vehicle speed when the wheel speed of the wheel becomes smaller than the vehicle speed when the vehicle speed is equal to or less than a certain vehicle speed. Calculate the lock integrated value, determine the lock state according to the wheel lock integrated value,
The vehicle stop determination device according to claim 7 , wherein the determination prohibiting unit corrects the predetermined time according to the wheel lock integrated value. The lock state determination means calculates the wheel lock value of each of the wheels, and integrates only the wheel lock value of the wheel having the largest absolute value of the wheel lock value among the wheels, thereby calculating the wheel lock integrated value. The vehicle stop determination device according to claim 8, wherein:

Images