JP5131581B2 - Braking force control device for vehicle - Google Patents

Description

  The present invention relates to a braking force control device for a vehicle, and in particular, is equipped with obstacle detection means for detecting an obstacle in front of the vehicle and measuring the distance thereof, and contact with the obstacle is unavoidable from the measurement result. The present invention relates to a braking force control device for a vehicle that automatically applies a brake when it is determined.

The vehicle is equipped with obstacle detection means such as a radar device that detects obstacles in front and measures the distance, and when it is determined that contact with obstacles is unavoidable from the measurement results, Some have a vehicle braking force control device for automatically applying a brake.
In this vehicular braking force control device, when it is determined that the possibility of contact with a front obstacle is high, the brake is automatically applied, and when it is determined that contact cannot be avoided, the vehicle is stronger. The brakes are automatically applied to reduce the speed when in contact with obstacles. Then, after the brake is applied, the vehicle braking force control device performs control to automatically release the brake applied after the predicted contact time with the obstacle has elapsed.

Conventionally, in an automatic braking device for a vehicle, a relative speed with respect to a preceding vehicle is calculated based on the inter-vehicle distance from the preceding vehicle and the own vehicle speed, and the degree of approach is determined. The degree of approach is determined from a first predetermined value. Is determined to be high, the brake actuator is operated to perform automatic braking. On the other hand, if the automatic braking is activated and the approach degree is determined to be lower than the second predetermined value, the brake operation is performed. In some cases, the automatic braking is canceled during the subsequent accelerator operation.
JP-A-8-310359

By the way, conventionally, in the vehicle braking force control device, when it is determined that the possibility of contact with an obstacle is high, the possibility of contact with the obstacle is reduced depending on the situation after the automatic brake is applied. The automatic brake is released. At this time, no warning was given to the driver to release the automatic brake applied. For this reason, if the applied automatic brake was suddenly released and the deceleration decreased, the driver felt uncomfortable or the maneuverability deteriorated.
As a function of the vehicle braking force control device, there is a function to give an alarm with a display on a meter or an alarm means of a buzzer to indicate that there is a possibility of contact with an obstacle before the automatic braking is applied. This warning is also issued when the automatic brake is applied. And when the possibility of contact with an obstacle becomes low, this alarm is also stopped. The driver knows that the possibility of contact with obstacles has been reduced due to the stop of this alarm, but since it is not known only by stopping this alarm whether the automatic brake is released or not, discomfort and maneuverability Has led to a decline.
Conventionally, such vehicle braking force control is performed as shown in the time chart of FIG. 6 or FIG.

FIG. 6 is a time chart when the possibility of contact with an obstacle increases and automatic braking is applied (when reaching brake control).
In FIG. 6, (1) shows an index of the possibility of contact with an obstacle, and the lower axis is a high axis and the upper axis is a low axis. (2) indicates a brake fluid pressure command value for operating the system. (3) indicates the deceleration generated in the vehicle. (4) shows an alarm indicating the possibility of contact with an obstacle. In FIG. 6A, the first threshold value Th1, the second threshold value Th2, and the third threshold value Th3 have a relationship of Th3 <Th1 <Th2.
Then, as shown in FIG. 6, in (1), when the possibility of contact approaches the front obstacle increases and the possibility of contact exceeds the first threshold value Th1 (time t1), It is judged that there is a possibility of contact, and an alarm is issued as shown in (4).
Furthermore, when the possibility of contact increases and the possibility of contact exceeds the second threshold Th2 (time t2), it is determined that the possibility of contact is high, and automatic braking is applied. At this time, as shown in (2), a brake fluid pressure command value is given.
As a result, as shown in (3), the deceleration of the vehicle gradually increases. Thereafter, as shown in (1), the possibility of contact begins to decrease (time t3), and when the possibility of contact falls below the third threshold Th3 (time t4), the possibility of contact disappears. The brake is released as shown in (2). Simultaneously with the release of the brake, the alarm is stopped as shown in (4).
Here, if the brake release is suddenly released, the maneuverability is affected. Therefore, conventionally, the brake is gradually released. However, it is generally preferable for the driver to release the brake and return to the normal driving state as soon as there is no risk of contact with the obstacle. However, releasing the brake early means that the deceleration increases, and this causes the inconvenience that the driver feels uncomfortable.

On the other hand, FIG. 7 is a flowchart in the case where the state has decreased before the possibility of contact with an obstacle becomes high and the state where the automatic brake is not applied has been reached.
In FIG. 7, as in the case of FIG. 6, (1) shows an index of the possibility of contact with an obstacle, with the lower part being a high axis and the upper part being a low axis. (2) indicates a brake fluid pressure command value for operating the system. (3) indicates the deceleration generated in the vehicle. (4) shows an alarm indicating the possibility of contact with an obstacle. In FIG. 7 (1), the first threshold value Th1, the second threshold value Th2, and the third threshold value Th3 are in a relationship of Th3 <Th1 <Th2.
Then, as shown in FIG. 7, at (1), the possibility of contact approaches the front obstacle increases, and when the possibility of contact exceeds the first threshold Th1 (time t1), It is judged that there is a risk of contact, and an alarm is issued as shown in (4). Thereafter, since the possibility of contact does not exceed the second threshold Th2 (time t2), automatic braking is not applied, and thereafter the possibility of contact begins to decrease (time t3), and the possibility of contact is first. If the threshold value Th3 is below 3 (time t4), it is determined that there is no risk of contact, and the alarm is stopped as shown in (4). During this time, the possibility of contact did not exceed the second threshold Th2, and thus the automatic brake was not applied. In this case, since the automatic brake is not applied, the deceleration does not occur, and the deceleration does not change even when the alarm is stopped. Further, the stop of the alarm (4) indicating that the possibility of the contact has been eliminated is the same in FIGS. 6 and 7, and it is not known that the deceleration will change thereafter only by stopping the alarm.
As a result, in the conventional control method, when there is no possibility of contact with an obstacle, it is not known that the deceleration of the vehicle changes abruptly thereafter, resulting in a sense of incongruity and a decrease in maneuverability.

  Accordingly, an object of the present invention is to notify the driver in advance that the deceleration of the vehicle due to the release of the brake will change, so that the driver can experience the change in the controllability of the vehicle due to the change in the braking force without feeling uncomfortable. An object of the present invention is to provide a vehicular braking force control device that can be used and contributes to the realization of stable vehicle control.

The present invention is provided with an obstacle detection means for detecting an obstacle ahead of the traveling direction, and a determination means for determining whether or not contact with an obstacle can be avoided from a detection result detected by the obstacle detection means, In the vehicular braking force control device provided with the control means provided with the automatic braking operation means for operating the braking means when the determination means determines that the contact with the obstacle is unavoidable, the control means includes: When the determination means determines that there is no longer any risk of contact with the obstacle, the automatic braking by the automatic braking operation means is canceled, and the vehicle deceleration at the time of releasing the automatic braking is preset. and when higher than the deceleration outputs a warning command signal, the cancel the automatic braking by the automatic braking operation unit, and deceleration is previously set in the vehicle at the time of cancellation of the automatic braking Has been at the time not higher than the deceleration is characterized in that it comprises an alarm command means does not output an alarm command signal.

  The vehicular braking force control device according to the present invention notifies the driver in advance that the vehicle deceleration due to the release of the brake changes, so that the driver can change that the controllability of the vehicle changes due to the change in the braking force. This makes it possible to experience a sense of incongruity and contribute to the realization of stable vehicle control.

The present invention makes it possible for the driver to experience a change in the controllability of the vehicle due to a change in braking force without causing a sense of incongruity, and to achieve stable vehicle control. This is realized by informing the driver in advance.
Hereinafter, embodiments of the present invention will be described in detail and specifically with reference to the drawings.

1 to 3 show a first embodiment of the present invention. In FIG. 3, reference numeral 1 denotes a vehicle braking force control device mounted on the vehicle. The vehicle braking force control device 1 is provided with an obstacle detection means (radar device) 2, a control means (controller) 3, and a braking control means (brake controller) 4. The control means 3 is in communication with obstacle detection means 2, braking control means 4, alarm means (meter (buzzer)) 5, and vehicle speed detection means (vehicle speed sensor) 6. The braking control means 4 communicates with a braking drive means (actuator) 7. The braking drive means 7 communicates with a braking means (brake device) 8.
The obstacle detection means 2 detects an obstacle ahead in the traveling direction, measures the distance to the obstacle and the relative speed, and outputs a signal of this measured value to the control means 3.
The control means 3 performs system control, inputs signals from the obstacle detection means 2 and the vehicle speed detection means 6, determines contact with the obstacles, and sends an automatic brake command signal to the brake control means 4. Is output.
The braking control means 4 inputs a brake command signal from the control means 3 and drives the braking drive means 7.
The alarm means 5 inputs an alarm command signal from the control means 3 to display an alarm,
Drive the buzzer.
The vehicle speed detection means 6 measures the speed of the host vehicle and outputs a signal of this measured value to the control means 3.
The brake drive means 7 is driven by the brake control means 4 to operate the brake means 8.

The control unit 3 includes a determination unit 3A that determines whether or not contact with an obstacle can be avoided from the detection result detected by the obstacle detection unit 2, and contact with the obstacle cannot be avoided by the determination unit 3A. If it is determined, automatic braking operation means 3B for operating the braking means 8 is provided.
Further, when it is determined by the determination means 3A that there is no longer any risk of contact with the obstacle, the control means 3 cancels the automatic braking by the automatic braking operation means 3B, and the vehicle when the automatic braking is released. When the deceleration is higher than the preset deceleration, the alarm command means 3C for outputting an alarm command signal is provided.

Next, the vehicle braking force control according to the first embodiment will be described based on the flowchart of FIG.
As shown in FIG. 1, when the program of the control means 3 is started (step A01), first, a determination index for determining the possibility of contact is calculated from the distance to the obstacle and the relative speed (step A02). For this determination index, a predicted contact time (contact predicted time = distance / relative speed) is usually used. This predicted contact time represents the time to contact that the current relative speed is assumed to continue. The smaller the value, the more immediately before the contact and the higher the possibility of contact.
Then, it is determined from this contact determination index whether or not “the possibility of contact is high” (step A03). This determination is made based on whether or not the predicted contact time is below a threshold value for determining that “the possibility of contact is high”. If step A03 is NO, the process returns to step A02.
If this step A03 is YES and it is determined that “the possibility of contact is high”, the brake control is started (step A04).
Then, the contact determination index is calculated again (step A05). Thereafter, it is determined from the contact determination index whether or not the state is “a state in which contact cannot be avoided” (step A06).
If this step A06 is NO and it is determined that it is not “a state where contact cannot be avoided”, it is determined from the contact determination index whether it is “a state where there is no risk of contact” (step A07). If this step A07 is NO and it is determined that it is not “a state in which there is no risk of contact”, the process returns to step A05.
If this step A07 is YES and it is determined that “there is no risk of contact”, the brake is released (step A08).
Then, it is determined whether or not a high deceleration is currently occurring (step A09). If this step A09 is YES and the deceleration is high, a brake release alarm is issued (step A10) and the program is ended (step A11). On the other hand, if step A09 is NO and the deceleration is not high, the program is immediately ended (step A11).
If step A06 is YES and it is determined that “contact is inevitable”, brake control stronger than the brake applied in step A04 is performed (step A12), and then predetermined control is performed. Run.
That is, in the flowchart of FIG. 1, when releasing a brake applied with a high possibility of contact with an obstacle, if a high deceleration occurs, a brake release alarm is issued and the operation is performed in advance. The brake is released, and the deceleration is suddenly changed (see Step A09 and Step A10).

Next, the vehicle braking force control according to the first embodiment will be described based on the time chart of FIG.
In FIG. 2, (1) shows an index of the possibility of contact with an obstacle, and the lower axis is a high axis and the upper axis is a low axis. (2) indicates a brake fluid pressure command value for operating the system. (3) indicates the deceleration generated in the vehicle. (4) indicates a brake release alarm. In FIG. 2 (1), the first threshold Th1, the second threshold Th2, and the third threshold Th3 are in a relationship of Th3 <Th1 <Th2.
Then, as shown in FIG. 2, in (1), the possibility of contact approaches the front obstacle increases, and the possibility of contact exceeds the first threshold value Th1 (time t1). When it is determined that the possibility of contact has exceeded the second threshold value Th2 (time t2), the brake fluid pressure command value is issued and the braking force is applied, and gradually (3) The deceleration of stand up. Thereafter, when the possibility of contact starts to decrease (time t3) and the possibility of contact reaches the third threshold value Th3 (time t4), there is no longer a possibility of contact, and the brake fluid pressure of (2) Decrease the command value gradually. At this time, the brake release alarm (4) is output (ON) to inform the driver that the deceleration suddenly decreases. When the brake fluid pressure command value in (2) is decreased, the brake release alarm is not output (OFF) (time t5), and the deceleration in (3) is slightly delayed. In this way, the brake release alarm informs the driver before the vehicle deceleration suddenly decreases, so that the driver can perform driving corresponding to the decrease in the attitude and deceleration in advance. In addition, the maneuverability is not lowered.
As a result, in this embodiment, when releasing the brake applied in a state where there is a high possibility of contact with an obstacle, the brake control is released separately from the alarm indicating that there is no longer a possibility of normal contact. Thereafter, a brake release alarm is issued to warn that the deceleration changes suddenly.
This notifies the driver in advance that the vehicle deceleration due to the release of the brake will change, so that the driver can make preparations for it, and thus the controllability of the vehicle will change due to the change in braking force. This makes it possible for the driver to experience this without discomfort, and allows the brakes to be released without causing a sense of discomfort or poor maneuverability, thereby contributing to the realization of stable vehicle control.

4 and 5 show a second embodiment of the present invention.
In the second embodiment, portions that perform the same functions as those of the first embodiment will be described with the same reference numerals.
The features of the second embodiment are as follows. That is, as shown in FIG. 4, when the automatic braking is canceled by the automatic braking operation unit 3B, the control unit 3 determines the brake fluid pressure decrease value from the start of the automatic braking until the set time (T0) elapses. It is made smaller than the value of the brake fluid pressure decrease after the set time has elapsed. In other words, from the response time of the driver's response to the brake release alarm and the response time of the decrease in the vehicle deceleration to the decrease in the hydraulic pressure command, the brake is reduced so that the deceleration decreases immediately after the time when the driver is ready to decrease the deceleration. The time for changing the hydraulic pressure command is obtained, and the hydraulic pressure release amount is decreased until that time, and thereafter, the hydraulic pressure release amount is controlled to increase the hydraulic pressure release amount.

The vehicle braking force control according to the second embodiment will be described with reference to the flowchart of FIG.
As shown in FIG. 4, when the program of the control means 3 is started (step B01), first, a determination index for determining the possibility of contact is calculated from the distance to the obstacle and the relative speed (step B02). For this determination index, a predicted contact time (contact predicted time = distance / relative speed) is usually used. This predicted contact time represents the time to contact that the current relative speed is assumed to continue. The smaller the value, the more immediately before the contact and the higher the possibility of contact.
Then, it is determined from this contact determination index whether or not “the possibility of contact is high” (step B03). This determination is made based on whether or not the predicted contact time is below a threshold value for determining that “the possibility of contact is high”. If step BA03 is NO, the process returns to step B02.
If this step B03 is YES and it is determined that “the possibility of contact is high”, the brake control is started (step B04).
Then, the contact determination index is calculated again (step B05). Thereafter, it is determined from the contact determination index whether the state is “a state in which contact cannot be avoided” (step B06).
If this step B06 is NO and it is determined that it is not “a state where contact cannot be avoided”, it is determined from the contact determination index whether it is “a state where there is no risk of contact” (step B07). When this step B07 is NO and it is judged that it is not "the state where the possibility of a contact has been lost", it returns to the said step B05.
If this step B07 is YES and it is determined that “there is no risk of contact”, the brake is released (step B08).
Then, it is determined whether or not a high deceleration is currently occurring (step B09). If this step B09 is YES and the deceleration is high, a brake release alarm is issued (step B10), and a brake fluid pressure command value (Pb) is calculated (step B11). The brake hydraulic pressure command value (Pb) is obtained by Pb (current command value) = Pb (previous command value) −P1 (current hydraulic pressure decrease amount).
Then, it is determined whether or not the set time T0 has elapsed from the start of the brake release alarm (step B12). If step B12 is NO, the process returns to step B11.
If step B12 is YES and step B09 is NO, the brake fluid pressure command value (Pb) is calculated again (step B13). The brake hydraulic pressure command value (Pb) is obtained by Pb (current command value) = Pb (previous command value) −P2 (current hydraulic pressure decrease amount). However, there is a relationship of P2> P1, that is, the decrease amount of the hydraulic pressure command value is made larger than P1.
Then, it is determined whether or not the brake fluid pressure command value has become zero (0) (step B14). If step B14 is NO, the process returns to step B13. If step B14 is YES, the program is ended (step B15).
If step B06 is YES and it is determined that “contact is inevitable”, brake control stronger than the brake applied in step B04 is performed (step B16), and then predetermined control is performed. Run.

Next, vehicle braking force control according to the second embodiment will be described based on the time chart of FIG.
In FIG. 5, (1) shows an index of the possibility of contact with an obstacle, and the lower part is high and the upper part is a low axis. (2) indicates a brake fluid pressure command value for operating the system. (3) indicates the deceleration generated in the vehicle. (4) indicates a brake release alarm. In FIG. 2 (1), the first threshold Th1, the second threshold Th2, and the third threshold Th3 are in a relationship of Th3 <Th1 <Th2.
Then, as shown in FIG. 5, in (1), the possibility of contact approaches the front obstacle increases, and the possibility of contact exceeds the first threshold value Th1 (time t1). When it is determined that the possibility of contact has exceeded the second threshold value Th2 (time t2), the brake fluid pressure command value is issued and the braking force is applied, and gradually (3) The deceleration of stand up. Thereafter, when the possibility of contact starts to decrease (time t3) and the possibility of contact reaches the third threshold value Th3 (time t4), there is no longer a possibility of contact, and the brake fluid pressure of (2) Decrease the command value gradually. At this time, the brake release alarm (4) is output (ON) to inform the driver that the deceleration suddenly decreases.
Thereafter, the brake release alarm output in (4) disappears (OFF) (time t5), and the driver's reaction time (time t4 to time t7) with respect to the brake release alarm given to the driver is set to T1, and the brake is released. If the response time (time t6 to time t7) from when the hydraulic pressure command value is suddenly reduced to when the vehicle deceleration decreases is T2, the brake hydraulic pressure command from the start of brake release to T0 = T1-T2. The value release amount is decreased, and the hydraulic pressure release amount is increased after the set time T0 (time t4 to time t6). .
By such control, the deceleration can be reduced immediately after the driver is ready for the decrease in the deceleration by the brake release alarm. That is, it is necessary to release the brake control earlier than the brake control is released. However, the sudden release leads to a sudden decrease in deceleration, which deteriorates the maneuverability. The brake is released in an optimum time that achieves both the quick release and the prevention of the deterioration of maneuverability.

  According to the vehicle braking force control of the second embodiment, the braking force reduction method is divided into two stages (time T0, time T2), and gradually decreases until the set time (T0) elapses from the start of reduction. Since the amount of reduction is increased after the set time (T0), the driver can be provided with a preparation time (a time required for a change in the maneuverability of the vehicle) for a decrease in deceleration. Thereby, the stable apparatus which is kind to a user can be provided. In addition, it is possible to release the brake as soon as possible and to release the brake while preventing both a sense of incongruity and a decrease in maneuverability.

  Notifying the driver in advance that the vehicle deceleration due to the release of the brake changes can be applied to other controls.

It is a flowchart of braking force control for vehicles in the 1st example. It is a time chart of braking force control for vehicles in the 1st example. 1 is a system configuration diagram of a vehicle braking force control apparatus according to a first embodiment. FIG. It is a flowchart of braking force control for vehicles in the 2nd example. It is a time chart of the braking force control for vehicles in the 2nd example. It is a time chart of braking force control for vehicles in the case of reaching brake control in the past. It is a time chart of braking force control for vehicles when not reaching brake control in the past.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle braking force control apparatus 2 Obstacle detection means 3 Control means 3A Determination means 3B Automatic braking operation means 3C Alarm command means 4 Braking control means 5 Alarm means 6 Vehicle speed detection means 7 Braking drive means 8 Braking means

Claims (2)

An obstacle detection means for detecting an obstacle ahead of the traveling direction is provided, a determination means for determining whether or not contact with the obstacle can be avoided from a detection result detected by the obstacle detection means, and an obstacle by the determination means When it is determined that contact with an object is unavoidable, the vehicle braking force control device includes a control unit provided with an automatic braking operation unit that activates the braking unit. When it is determined that there is no longer any risk of contact with an obstacle, the automatic braking by the automatic braking operation means is canceled, and the vehicle deceleration at the time of releasing the automatic braking is greater than a preset deceleration. when even higher outputs a warning command signal to release the automatic braking by the automatic braking operation unit, and deceleration deceleration of the vehicle at the time of cancellation of the automatic braking is set in advance When not higher than, the vehicle braking force control apparatus characterized by comprising an alarm command means does not output an alarm command signal.   In the release of the automatic braking by the automatic brake actuating means, the control means calculates the value of the brake hydraulic pressure decrease degree from the start of the automatic brake release until the set time elapses, and the brake hydraulic pressure decrease degree after the set time elapses. The vehicular braking force control apparatus according to claim 1, wherein the vehicular braking force control apparatus is smaller than the value.

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