WO2012111035A1

WO2012111035A1 - Collision avoidance braking device and collision avoidance braking method

Info

Publication number: WO2012111035A1
Application number: PCT/JP2011/000792
Authority: WO
Inventors: 亮猪俣
Original assignee: トヨタ自動車株式会社
Priority date: 2011-02-14
Filing date: 2011-02-14
Publication date: 2012-08-23

Abstract

Provided is a collision avoidance braking device and a collision avoidance braking method in which the braking force and other parameters are controlled in an appropriate manner, taking the state of degradation of the brake pad into account, to avoid a collision between a vehicle and an obstacle with a high degree of accuracy. When the driver operates the brake, a computation unit (14) calculates the estimated friction coefficient μ on the basis of vehicle information and the brake hydraulic pressure obtained from a vehicle information obtaining unit (11) and a brake operation detector (13). Next, the computation unit (14) estimates the state of degradation of the brake pad from the estimated friction coefficient μ, and estimates the actual deceleration characteristics of the vehicle on the basis of the state of degradation of the brake pad. Next, the computation unit (14) calculates and stores a corrective value for causing the actual deceleration characteristics to conform to deceleration characteristics required by an automatic brake controller (16). Then, when there is a need for the vehicle to avoid an obstacle, the computation unit (14) uses the stored corrective value to correct the braking force presented by the automatic brake controller (16) to a brake actuator (52).

Description

Collision avoidance braking device and collision avoidance braking method

The present invention relates to a collision avoidance braking device and a collision avoidance braking method, and more specifically, an apparatus that is mounted on a vehicle and that automatically controls a brake to assist in avoiding a collision with an obstacle of the vehicle, and its It relates to a method performed by an apparatus.

As one of the safety devices mounted on the vehicle, a collision avoidance braking device that recognizes obstacles around the vehicle and assists the driver's operation so that the traveling vehicle can avoid it without colliding with the obstacle has been developed. Has been. For example, see Patent Document 1 and Patent Document 2.

These conventional collision avoidance braking devices detect and calculate parameters necessary for control using various sensors mounted on the vehicle. The parameters include, for example, the speed of the vehicle, the steering angle of the vehicle, the weight of the vehicle, the distance to the obstacle, the direction of the obstacle, the slope of the road surface, and the friction coefficient of the road surface. Then, the collision avoidance braking device determines the braking operation start timing (hereinafter referred to as braking start timing) necessary to prevent the vehicle from colliding with the obstacle and the braking effectiveness based on the parameters obtained by the detection and calculation. The condition (hereinafter referred to as braking force) is obtained and the brake is automatically controlled.

JP 2008-49932 A Japanese Patent Laid-Open No. 5-294218

As a factor for determining the braking start timing and braking force necessary for the vehicle not to collide with an obstacle, there is a brake pad (or brake shoe) state in addition to the parameters described above. That is, since the brake pad (or brake shoe) generates a braking force by contact with the disk rotor (or brake drum), deterioration over time occurs such that the contact surface is worn by long-term use. For this reason, a brake pad that has deteriorated over time has a smaller braking force than a brake pad that does not deteriorate (see FIG. 4). Therefore, it is desirable to include the deterioration state of the brake pad in the parameters for determining the braking start timing and the braking force.

However, the conventional collision avoidance braking device does not consider the deterioration state of the brake pad as a parameter for determining the braking start timing and the braking force. For this reason, in the conventional collision avoidance braking device, when the deterioration of the brake pad is progressing, the vehicle cannot avoid the collision with the obstacle with the braking start timing and the braking force obtained by the calculation. It is also possible.

Therefore, an object of the present invention is to provide a collision avoidance braking apparatus that can avoid a vehicle from colliding with an obstacle by appropriately controlling the braking start timing and the braking force in consideration of the deterioration state of the brake pad. It is to provide a collision avoidance braking method.

The present invention is directed to a collision avoidance braking device that assists in avoiding collision of a vehicle with an obstacle using automatic brake control. In order to achieve the above object, a collision avoidance braking apparatus according to the present invention includes a detection unit that detects a brake operation by a driver, an acquisition unit that acquires a vehicle condition including at least a deceleration of the vehicle, and a brake operation detection. And a correction unit that estimates a deterioration state of the brake pad from the vehicle deceleration acquired at times, and corrects the vehicle deceleration at the time of execution of the automatic brake control according to the estimated deterioration state of the brake pad. Typically, the detection unit acquires the brake hydraulic pressure at the time of detecting the brake operation. The correction unit includes a first estimation unit that estimates a deterioration state of the brake pad based on a relationship between the brake hydraulic pressure acquired when the brake operation is detected and the vehicle deceleration, and the estimated deterioration state of the brake pad. And a first estimation unit that estimates an actual deceleration characteristic of the current vehicle and a first deceleration characteristic that is required for the vehicle to avoid a collision in the vehicle condition at the time of the brake operation. A second calculation unit that calculates a correction value for eliminating a state where the estimated actual deceleration characteristic and the required deceleration characteristic are different from each other, and automatically using the correction value And a control unit that executes brake control.

With this configuration, it is possible to improve the situation where the deceleration characteristic required for the vehicle for avoiding a collision and the deceleration characteristic actually generated by the deteriorated brake pad deviate.

In the present collision avoidance braking device, the correction unit further includes a storage unit that stores the correction values calculated by the second calculation unit by classifying the correction values into a plurality of classes classified according to vehicle conditions at the time of the brake operation, and the control unit Thus, when collision avoidance is required, it is desirable to read out the correction value classified into the class that matches the vehicle condition at that time from the storage unit and execute the automatic brake control using the read correction value. Regarding vehicle conditions, it is preferable to classify at least one of vehicle speed, vehicle weight, road gradient, vehicle outside temperature, travel area weather, and brake operation frequency.

In such a configuration, since a plurality of correction values corresponding to vehicle conditions such as vehicle weight and road gradient are stored, the relationship between the brake hydraulic pressure and the deceleration characteristics greatly changes depending on the vehicle conditions. Even in such a case, the automatic brake control can be appropriately executed.

Further, the automatic brake control executed by the control unit of the collision avoidance braking device is performed according to the deceleration characteristic obtained by correcting the required deceleration characteristic calculated by the first calculation unit with the read correction value. Alternatively, it may be performed at the braking start timing corrected with the read correction value of the specified braking start timing, or the padding process start timing corrected with the read correction value of the specified padding processing start timing. May be done.

Regardless of the method used to execute automatic brake control, the overall braking force exhibited by the automatic brake control is substantially the same, and the deceleration characteristics required for the vehicle for collision avoidance have deteriorated. It is possible to improve the situation in which the deceleration characteristic actually generated by the brake pad deviates.

Further, the first estimation unit may perform control so as not to estimate the deterioration state of the brake pad when the vehicle condition exceeds a predetermined range.
By controlling in this way, it is possible to prevent a correction value with low accuracy from being calculated when the vehicle conditions are extreme.

The second calculation unit may obtain an average value of a plurality of correction values calculated during a predetermined period, and set the average value as a correction value used for automatic brake control.
With this setting, it is possible to provide highly accurate collision avoidance braking even under unstable vehicle traveling conditions in which the correction value calculated every time a brake operation occurs changes greatly. Become.

The present invention is also directed to a collision avoidance braking method executed by a collision avoidance braking apparatus that supports avoidance of a collision with an obstacle of a vehicle using automatic brake control. In order to achieve the above object, in the collision avoidance braking method of the present invention, the detection unit detects the brake operation by the driver, and the acquisition unit acquires the vehicle condition including at least the deceleration of the vehicle. The step and the calculation unit estimate the brake pad deterioration state from the vehicle deceleration acquired when the brake operation is detected, and the vehicle deceleration during the execution of the automatic brake control according to the estimated brake pad deterioration state And a step of correcting. Typically, in the detecting step, the brake hydraulic pressure at the time of detecting the brake operation is acquired. Further, the correcting step includes a step in which the calculation unit estimates a deterioration state of the brake pad based on a relationship between the brake hydraulic pressure acquired when the brake operation is detected and the deceleration of the vehicle, and the calculation unit is estimated. A step of estimating the actual deceleration characteristic of the current vehicle based on the deterioration state of the brake pad, and a deceleration characteristic required for the vehicle for avoiding a collision in the vehicle condition at the time of the brake operation Calculating the correction value for eliminating the state where the estimated actual deceleration characteristic and the required deceleration characteristic are different from each other, and the control unit Performing automatic brake control using the value.

The collision avoidance braking method of the present invention is provided in the form of a program for causing a computer to execute a series of processing procedures. This program may be introduced into a computer storage device via a computer-readable recording medium, or may be directly executed from the recording medium. This recording medium is a semiconductor memory such as a ROM, a RAM or a flash memory, a magnetic disk memory such as a flexible disk or a hard disk, an optical disk memory such as a CD-ROM, a DVD or a BD, a memory card, and the like. And other communication media.

According to the collision avoidance braking apparatus and the collision avoidance braking method of the present invention, the brake start timing and the braking force can always be appropriately controlled in consideration of the deterioration state of the brake pad. Therefore, it is possible to prevent a situation where an obstacle cannot be avoided.

FIG. 1 is a diagram showing a schematic configuration of a vehicle brake system including a collision avoidance braking apparatus according to first to fourth embodiments of the present invention. FIG. 2 is a flowchart showing a processing procedure of a correction value acquisition operation performed by the collision avoidance braking apparatus according to the first, third, and fourth embodiments. FIG. 3 is a diagram showing the characteristics of the friction coefficient μ during the brake operation. FIG. 4 is a diagram showing the relationship between brake hydraulic pressure and deceleration. FIG. 5 is a diagram conceptually illustrating an example of correction values classified and stored for each class in the storage unit 15 of the first, third, and fourth embodiments. FIG. 6 is a flowchart showing the procedure of the correction value reflecting operation performed by the collision avoidance braking apparatus according to the first to fourth embodiments. FIG. 7 is a flowchart illustrating another processing procedure of the correction value acquisition operation performed by the collision avoidance braking apparatus according to the first embodiment. FIG. 8 is a flowchart illustrating a processing procedure of a correction value acquisition operation performed by the collision avoidance braking apparatus according to the second embodiment. FIG. 9 is a flowchart showing a detailed processing procedure of step S801 shown in FIG. FIG. 10 is a diagram illustrating the concept of the average correction value obtained by the calculation unit 14. FIG. 11 is a diagram conceptually illustrating an example of the correction value and the average correction value for each class stored in the storage unit 15 of the second embodiment. FIG. 12 shows the difference in braking start timing between the automatic brake control (a) performed by the conventional collision avoidance braking apparatus and the automatic brake control (b) performed by the collision avoidance braking apparatus according to the third embodiment of the present invention. FIG. FIG. 13 shows the start timing of the backpacking process in the automatic brake control (a) performed by the conventional collision avoidance braking apparatus and the automatic brake control (b) performed by the collision avoidance braking apparatus according to the fourth embodiment of the present invention. It is a figure which shows a difference.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
FIG. 1 is a diagram showing a schematic configuration of a vehicle brake system including a collision avoidance braking apparatus according to a first embodiment of the present invention. The vehicle brake system shown in FIG. 1 includes a collision avoidance braking apparatus according to the first embodiment, a brake control unit 51, and four brake actuators 52. The collision avoidance braking device according to the first embodiment includes a vehicle information acquisition unit 11, an obstacle detection unit 12, a brake operation detection unit 13, a calculation unit 14, a storage unit 15, and an automatic brake control unit 16.

First, each configuration of the collision avoidance braking apparatus according to the first embodiment will be briefly described.
The vehicle information acquisition unit 11 includes information acquisition mechanisms such as various sensors and GPS, and includes vehicle speed, vehicle deceleration, vehicle weight, road gradient, vehicle outside temperature, travel area weather, and brake operation. Information about vehicle conditions (or states) such as frequency (hereinafter referred to as vehicle information) is acquired. For example, the speed of the vehicle can be acquired using a vehicle speed sensor. The deceleration of the vehicle can be acquired using a deceleration sensor. The weight of the vehicle is obtained from the displacement amount of the suspension sensor. The road gradient is obtained from the difference between the differential value of the wheel speed and the sensor value using a vehicle speed sensor and a gyro sensor. The outside air temperature of the vehicle can be acquired using a temperature sensor. The weather in the travel area can be acquired from weather information via GPS or the operating state of the wiper. The brake operation frequency can be acquired from the lighting state of the stop lamp. This vehicle information is output to the calculation unit 14.

The obstacle detection unit 12 includes a laser radar, a microwave radar, a millimeter wave radar, an ultrasonic radar, or the like, and detects an obstacle present around the vehicle. The obstacle detection unit 12 acquires information such as a relative distance from the vehicle to the obstacle, a relative speed between the vehicle and the obstacle, and a direction in which the obstacle exists (hereinafter referred to as obstacle information). For example, the obstacle information can be acquired by transmitting a radar wave from the vehicle toward the surroundings and receiving a reflected wave that hits the obstacle and returns to the vehicle. This obstacle information is output to the calculation unit 14.

The brake operation detection unit 13 includes a pedal sensor, a hydraulic pressure sensor, and the like, and brake operation by the driver, that is, whether or not the brake pedal is depressed, and information on brake hydraulic pressure according to the depression amount of the brake pedal (hereinafter referred to as brake information). ) To get. This brake information is output to the calculation unit 14 and the brake control unit 51.

The calculation unit 14 inputs vehicle information from the vehicle information acquisition unit 11, obstacle information from the obstacle detection unit 12, and brake information from the brake operation detection unit 13, and performs necessary calculations based on each information. . When it is determined that the vehicle is traveling normally, the calculation unit 14 sequentially stores correction values calculated at a predetermined timing in the storage unit 15 so that the vehicle needs to avoid a collision with an obstacle. If it is determined that there is, an appropriate instruction is given to the automatic brake control unit 16 based on the correction value already stored in the storage unit 15.

The storage unit 15 stores a correction value for correcting the braking force generated by the automatic brake control performed by the automatic brake control unit 16. This correction value is stored in correspondence with each of a plurality of classes that are preliminarily classified according to predetermined vehicle conditions for a plurality of pieces of information included in the vehicle information. Details of the plurality of classes will be described later.

When the calculation unit 14 determines that the vehicle needs to avoid a collision with an obstacle, the automatic brake control unit 16 calculates a deceleration characteristic required for the collision avoidance in the vehicle condition at that time. Then, the calculated deceleration characteristic is corrected with a correction value given from the calculation unit 14. Then, the automatic brake control unit 16 controls the braking force generated by the brake actuators 52 provided on the four wheels of the vehicle according to the corrected required deceleration characteristic. This control is performed independently of the brake operation according to the driver's intention. Control of the braking force of the brake actuator 52 according to the brake operation according to the driver's intention is performed via the brake control unit 51.

Next, a collision avoidance braking method performed by the collision avoidance braking apparatus according to the first embodiment having the above-described configuration will be described with further reference to FIGS.
FIG. 2 is a flowchart showing a processing procedure of a correction value acquisition operation performed by the collision avoidance braking apparatus according to the first embodiment. FIG. 3 is a diagram showing the characteristics of the friction coefficient μ during the brake operation. FIG. 4 is a diagram showing the relationship between brake hydraulic pressure and deceleration. FIG. 5 is a diagram conceptually illustrating an example of the correction value for each class stored in the storage unit 15. FIG. 6 is a flowchart showing a processing procedure of a correction value reflecting operation performed by the collision avoidance braking apparatus according to the first embodiment.

In the collision avoidance braking apparatus of the present invention, the correction value acquisition operation and the correction value reflection operation are performed.
The correction value acquisition operation is an operation that is performed when the driver performs a brake operation during normal driving without an obstacle around the vehicle. The deterioration state of the brake pad is estimated, and the vehicle is reduced based on the estimated deterioration state. A correction value related to the speed characteristic is obtained, and the obtained correction value is stored in association with the vehicle information for each class.
The correction value reflecting operation is an operation performed when an obstacle exists around the vehicle and the vehicle needs to avoid the obstacle, and is stored in association with a class that matches the vehicle condition at that time. Using the correction value, the deceleration characteristic required in the automatic brake control is corrected.
Hereinafter, the correction value acquisition operation and the correction value reflection operation will be described.

1. Correction Value Acquisition Operation In FIG. 2, the correction value acquisition operation is started when the vehicle is started by turning on the ignition button or the like. After the vehicle is started, the brake operation detection unit 13 detects a brake operation performed by the driver (step S201). When a brake operation is detected in step S201, the vehicle information acquisition unit 11 acquires vehicle information at the time of detection (step S202). Moreover, the brake operation detection part 13 acquires the brake hydraulic pressure at the time of detection (step S203).

When the vehicle information and the brake hydraulic pressure are acquired, the calculation unit 14 calculates the estimated friction coefficient μ according to the following mathematical formula (step S204). In this equation, G is the deceleration of the vehicle, L is the weight of the vehicle, R is the tire radius, P is the brake hydraulic pressure, A is the W / C area, and r is the effective braking radius.
μ = G × L × R / (2 × P × A × r)
As shown in FIG. 3, the estimated friction coefficient μ has a characteristic that converges to a certain value when a predetermined time elapses. Accordingly, in order to obtain a stable estimated friction coefficient μ, an estimated friction coefficient μ having a fluctuation range Y within a period X in which a predetermined time has elapsed since the occurrence of the brake operation is obtained (step S205; Yes). If the estimated friction coefficient μ does not have the fluctuation range Y within the period X after a predetermined time has elapsed since the occurrence of the brake operation (step S205; No), the estimated estimated friction coefficient μ cannot be obtained. As a result, the correction value is not calculated.

Next, the calculation unit 14 estimates the deterioration state of the brake pad from the calculated estimated friction coefficient μ (step S206). That is, the calculation unit 14 determines that the brake pad is less deteriorated or less deteriorated as the estimated friction coefficient μ is larger. In the example of FIG. 3, the characteristics of the friction coefficient μ regarding the brake pad without deterioration (new article) and the brake pad with deterioration (deteriorated article) are shown.

Next, the calculation unit 14 estimates the actual deceleration characteristic of the vehicle under the current vehicle conditions based on the estimated deterioration state of the brake pad (step S207). Here, the relationship between the brake hydraulic pressure and the deceleration has the characteristic shown in FIG. 4 in the range where the pressure increase gradient of the brake hydraulic pressure changes linearly. That is, when the brake hydraulic pressure is the same, the deceleration when the brake pad is deteriorated (deteriorated product) is proportionally smaller than the deceleration when the brake pad is not deteriorated (new product). Therefore, the actual deceleration characteristic of the vehicle that matches the current deterioration state of the brake pad is estimated from the relationship shown in FIG.

And the calculating part 14 calculates the correction value which corrects the deceleration characteristic requested | required of a vehicle, when avoiding the collision with an obstruction (step S208). This correction value is obtained when the actual deceleration characteristic of the vehicle obtained by braking the brake actuator 52 by the automatic brake control unit 16 during the collision avoidance braking is the deceleration characteristic required due to the deterioration of the brake pad. This is to prevent divergence. That is, this correction value is used to correct the required deceleration characteristic in order to eliminate the difference between the actual deceleration characteristic and the required deceleration characteristic.

The above-described change characteristic of the estimated friction coefficient μ (FIG. 3) and brake hydraulic pressure-deceleration characteristic (FIG. 4) vary greatly depending on the vehicle weight, road gradient, and the like. Therefore, the calculation unit 14 calculates correction values for a plurality of classes having different vehicle conditions. The plurality of correction values calculated for each of the plurality of classes are classified together with the vehicle information of each class and stored in the storage unit 15 (step S209). FIG. 5 is a diagram conceptually illustrating an example of correction values classified and stored for each class in the storage unit 15.

The processes in steps S201 to S209 described above are repeated until the vehicle stops the engine, for example, when the ignition button is turned off (step S210). Through this correction value acquisition operation that is repeatedly performed, a correction value corresponding to the actual deterioration state of the brake pad during normal traveling can be acquired for each class classified with respect to various vehicle conditions of the vehicle.

Note that, by repeatedly performing the correction value acquisition operation, the correction value may be calculated again for the class for which the correction value is already stored in the storage unit 15. In this case, in the first embodiment, the correction value of the corresponding class is updated by overwriting every time the latest correction value is calculated.

2. Correction value reflection operation This correction value reflection operation is performed in parallel with the correction value acquisition operation described above.
In FIG. 6, the correction value reflecting operation is started when an obstacle present around the vehicle is detected by the obstacle detection unit 12. When an obstacle is detected, the vehicle information acquisition unit 11 acquires vehicle information at the time of detecting the obstacle (step S601). The calculation unit 14 analyzes the obstacle information given from the obstacle detection unit 12 and the vehicle information given from the vehicle information acquisition unit 11, and calculates a collision risk degree indicating that the vehicle may collide with the obstacle ( Step S602). Then, the calculation unit 14 determines whether or not the calculated collision risk is equal to or greater than a predetermined value (step S603).

If it is determined in step S603 that the collision risk is greater than or equal to a predetermined value, the calculation unit 14 selects a vehicle included in the vehicle information acquired in step S601 from the plurality of classes stored in the storage unit 15. One class having a vehicle condition that matches the condition is selected (step S604). When a class is selected in step S604, the calculation unit 14 reads the correction value of the selected class from the storage unit 15 (step S606). Then, the calculation unit 14 instructs the automatic brake control unit 16 to correct the requested deceleration characteristic according to the read correction value (step S607). Then, the automatic brake control unit 16 controls the braking force of the brake actuator 52 according to the corrected required deceleration characteristic (step S608). As a result, the vehicle can have a deceleration characteristic that substantially matches the deceleration characteristic required by the automatic brake control unit 16.

If the correction value is not yet stored in the class selected in step S604, the correction value reflecting operation is terminated without correcting the braking force using the correction value (step S605; No). The automatic brake control unit 16 performs normal automatic brake control.

As described above, according to the collision avoidance braking apparatus according to the first embodiment of the present invention, the correction value corresponding to the actual deterioration state of the brake pad is calculated during normal traveling, and the vehicle, the obstacle, In a scene where the collision of the vehicle should be avoided, the calculated correction value is reflected in the automatic brake control. As a result, it is possible to improve the situation in which the deceleration characteristic required by the automatic brake control unit 16 and the deceleration characteristic actually generated by the deteriorated brake pad deviate from each other. Therefore, the present collision avoidance braking apparatus can always apply the optimum braking force to the brake actuator 52, thereby improving the accuracy of obstacle avoidance of the vehicle.

In the first embodiment, the case where the correction value acquisition operation is always executed when the brake is operated by the driver regardless of the condition of the vehicle has been described.
However, when the vehicle conditions are extreme, for example, when the number of passengers and luggage is large and the vehicle weight is very heavy, when the braking force balance of the four wheels is poor due to a steep road slope, the frequency of brake operation is high and the temperature of the brake pad is high. It can be said that it is difficult to calculate a highly accurate correction value when the temperature is extremely high, when the temperature and weather are deteriorated, and the friction coefficient of the road surface is extremely changed. Therefore, as shown in FIG. 7, steps S701 and S702 are inserted between step S202 and step S203 in FIG. 2, and a correction value acquisition operation is performed in a case where it is determined that a highly accurate correction value cannot be obtained. It may not be performed.

<Second Embodiment>
In the first embodiment, the correction value (FIG. 2: step S208) calculated each time in response to the brake operation performed by the driver is overwritten and stored in the corresponding class in the storage unit 15 (FIG. 2: step). S209). Therefore, the correction value stored in the storage unit 15 is only one latest correction value (see FIG. 5).
However, in reality, it is conceivable that the deterioration state of the brake pad, which is estimated based on the temperature of the brake pad when the correction value acquisition operation is performed, the wetness, the amount of attached rust, and the like varies. Therefore, there may be a case where an obstacle cannot be actually avoided only based on the correction value calculated by the latest brake operation.
Therefore, in the second embodiment, a correction value calculation method for further improving the accuracy of obstacle avoidance by the vehicle will be described.

The schematic configuration of the vehicle brake system including the collision avoidance braking apparatus according to the second embodiment of the present invention is the same as that of the collision avoidance braking apparatus according to the first embodiment shown in FIG. However, in the collision avoidance braking apparatus according to the second embodiment, the processing of the calculation unit 14 and the stored contents of the storage unit 15 are slightly different from those of the collision avoidance braking apparatus according to the first embodiment.
Hereinafter, the collision avoidance braking apparatus according to the second embodiment will be described focusing on the different processes.

FIG. 8 is a flowchart showing a processing procedure of a correction value acquisition operation performed by the collision avoidance braking apparatus according to the second embodiment. The correction value acquisition operation is as described in the first embodiment. In the second embodiment, the correction value storage process in step S801 in FIG. 8 is different from that in FIG. The detailed process of step S801 in FIG. 8 is shown in the flowchart of FIG.

In FIG. 9, the calculating part 14 first memorize | stores the correction value calculated by step S208 of FIG. 8 in the class applicable to the vehicle conditions at the time of the brake operation in the memory | storage part 15 (step S901). At this time, the calculation unit 14 adds the correction value calculated this time to the storage unit 15 without deleting the previously calculated correction value already stored. Next, the calculation unit 14 reads out a plurality of correction values stored in a predetermined period from all the correction values of the class to which the correction value is added from the storage unit 15, and averages the plurality of correction values. A value is obtained (step S902). FIG. 10 shows the concept of the average correction value obtained by the calculation unit 14. In addition, what is necessary is just to set arbitrarily the length of a predetermined period according to the material, durability, etc. of a brake pad.

In step S902, when the current average correction value is obtained, the calculation unit 14 checks whether the past average correction value is already stored in the storage unit 15 (step S903). When the past average correction value is stored as a result of the confirmation in step S903, the calculation unit 14 obtains a difference between the past average correction value and the current average correction value (step S904, FIG. 10). . If the past average correction value is not stored as a result of the confirmation in step S903, the calculation unit 14 newly stores the current average correction value in the storage unit 15 (step S908).

Next, the calculation unit 14 determines whether or not the difference obtained in step S904 is equal to or greater than a predetermined threshold (step S905). If it is determined in step S905 that the difference is greater than or equal to the threshold, the calculation unit 14 stores the current average correction value in the storage unit 15 by overwriting (step S908). On the other hand, when it is determined in step S905 that the difference is not greater than or equal to the threshold, the calculation unit 14 also determines whether the previously performed difference is greater than or equal to the threshold for other classes other than the class to which the correction value is added. Is checked, and it is determined whether or not the class having the difference equal to or greater than the threshold exceeds half of all classes (step S906).

When it is determined in step S906 that the class whose difference is equal to or greater than the threshold exceeds half of all classes, the calculation unit 14 overwrites the storage unit 15 with the current average correction value obtained in the class in which the correction value is added. (Step S908). However, if it is determined in step S906 that the class whose difference is equal to or greater than the threshold value is less than half of all classes, the calculation unit 14 does not store the current average correction value in the storage unit 15 and stores the past average correction. The value is held as it is (step S907).

FIG. 11 is a diagram conceptually illustrating an example of the correction value and the average correction value for each class stored in the storage unit 15. As shown in FIG. 11, in the collision avoidance braking apparatus according to the second embodiment, the correction value is added each time a correction value is calculated for each class, and the obtained average correction value is also stored. The Note that the retention period of the stored correction value may be determined in advance (for example, one month or one year) or may not be determined.

The correction value reflecting operation performed by the collision avoidance braking apparatus according to the second embodiment is the same as that in the flowchart of FIG. 6 described in the first embodiment, in which the calculation unit 14 calculates the average correction value of the selected class. The data is read from the storage unit 15 (step S606 in FIG. 6), and the automatic brake control unit 16 is instructed to correct the requested deceleration characteristic according to the read average correction value (step S607 in FIG. 6).

As described above, according to the collision avoidance braking apparatus according to the second embodiment of the present invention, the deceleration characteristic required by the automatic brake control using the average correction value considering the change transition of the deterioration state of the brake pad. Correct. As a result, it is possible to provide highly accurate collision avoidance braking even under unstable vehicle traveling conditions in which the correction value calculated every time a braking operation occurs.

<Third Embodiment>
In the first and second embodiments, in order to improve the deviation state between the deceleration characteristic required by the automatic brake control unit 16 and the deceleration characteristic actually generated by the deteriorated brake pad, The method of correcting the deceleration characteristic required by the automatic brake control unit 16 based on the deterioration state of the brake pad estimated from the brake operation, in other words, controlling the braking force of the brake actuator 52 has been described. That is, this is a technique for improving the braking effectiveness as the brake pads deteriorate.

On the other hand, in the third embodiment, a method for controlling the braking timing of the brake actuator 52 based on the deterioration state of the brake pad will be described. In other words, this is a technique for speeding up the start of braking with the deterioration of the brake pads.

The schematic configuration of the vehicle brake system including the collision avoidance braking apparatus according to the third embodiment of the present invention is the same as that of the collision avoidance braking apparatus according to the first embodiment shown in FIG. However, in the collision avoidance braking apparatus according to the third embodiment, the processing of the calculation unit 14 is different from that of the collision avoidance braking apparatus according to the first embodiment.
Hereinafter, the collision avoidance braking apparatus according to the third embodiment will be described focusing on the different processes.

In the collision avoidance braking apparatus according to the third embodiment, the processing in step S607 in the correction value reflecting operation (FIG. 6) described above is different. Specifically, the calculation unit 14 reads the correction value of the class selected in step S604 from the storage unit 15 (step S606). Then, the calculation unit 14 outputs the read correction value to the automatic brake control unit 16 and instructs the automatic brake control unit 16 to advance the braking start timing given to the brake actuator 52 according to the correction value (step S607). .

FIG. 12 shows the difference in braking start timing between the conventional automatic brake control (a) and the automatic brake control (b) of the present invention.
As shown in FIG. 12, in the collision avoidance braking apparatus according to the third embodiment, the braking start timing of the brake actuator 52 is advanced by a correction value calculated based on the deterioration state of the brake pad. Therefore, according to this control, even if the braking force of the brake actuator 52 is not increased, the total braking force from the brake ON to the brake OFF is substantially equal to the case where the braking force of the brake actuator 52 is increased. can do.

As described above, according to the collision avoidance braking apparatus according to the third embodiment of the present invention, the braking start timing of the automatic brake control is corrected using the correction value corresponding to the deterioration state of the brake pad. As a result, it is possible to improve the situation where the deceleration required by the automatic brake control unit 16 and the deceleration actually caused by the deteriorated brake pad are different.

In the third embodiment, the example in which only the braking start timing of the automatic brake control is corrected based on the correction value has been described. However, the correction of the braking start timing of the automatic brake control of the third embodiment is combined with the correction of the required deceleration characteristics described in the first and second embodiments, that is, the correction of the braking force of the automatic brake control. May be performed.

In the third embodiment, the description has been made on the assumption that the braking start timing of the automatic brake control is also sequentially changed according to the correction value for which the successive value is changed. However, when the calculation unit 14 determines whether or not the brake pad has deteriorated and determines that the brake pad has deteriorated, control may be performed so that the braking start timing of the automatic brake control is advanced by a predetermined time. . In this case, the determination as to whether or not the brake pads are deteriorated is that the difference is greater than or equal to the threshold value for half of all classes stored in the storage unit 15 in step S906 (FIG. 9) of the second embodiment. Depending on whether or not, it can be considered.

<Fourth Embodiment>
In general, immediately before automatic brake control is performed, the brake pad and disk rotor are brought into contact with each other to the extent that deceleration does not occur, and the clearance existing between the two is filled to improve the deceleration response during automatic brake control. A process called “packing” is performed. Normally, this padding process does not have to be continued beyond the time required to fill the clearance. However, in a state where the brake pad has deteriorated, the effect of raising the temperature of the brake pad and the effect of scraping off the rust adhering to the disc rotor can be expected by extending the padding process for a long time, thereby improving the effectiveness of the brake pad. it is conceivable that.

Therefore, in the fourth embodiment, a method for controlling the timing for starting the backpacking process based on the deterioration state of the brake pad will be described.

The schematic configuration of the vehicle brake system including the collision avoidance braking apparatus according to the fourth embodiment of the present invention is the same as that of the collision avoidance braking apparatus according to the first embodiment shown in FIG. However, in the collision avoidance braking apparatus according to the fourth embodiment, the processing of the calculation unit 14 is different from that of the collision avoidance braking apparatus according to the first embodiment.
Hereinafter, the collision avoidance braking apparatus according to the fourth embodiment will be described focusing on the different processes.

In the collision avoidance braking apparatus according to the fourth embodiment, the processing in step S607 in the correction value reflecting operation (FIG. 6) described above is different. Specifically, the calculation unit 14 reads the correction value of the class selected in step S604 from the storage unit 15 (step S606). Then, the calculation unit 14 outputs the read correction value to the automatic brake control unit 16 and instructs the automatic brake control unit 16 to advance the start timing of the filling process given to the brake actuator 52 according to the correction value. (Step S607).

FIG. 13 shows the difference in the start timing of the backpacking process between the conventional automatic brake control (a) and the automatic brake control (b) of the present invention.
As shown in FIG. 13, in the collision avoidance braking apparatus according to the fourth embodiment, the start timing of the loosening process of the brake actuator 52 is advanced by a correction value calculated based on the deterioration state of the brake pad. Therefore, according to this control, the brake pad temperature rises sufficiently to improve the braking effectiveness, so that the total braking force from the brake ON to the brake OFF can be achieved without increasing the braking force of the brake actuator 52. Can be substantially equivalent to the case where the braking force of the brake actuator 52 is increased.

As described above, according to the collision avoidance braking apparatus according to the fourth embodiment of the present invention, the correction processing start timing of the automatic brake control is corrected using the correction value according to the deterioration state of the brake pad. . As a result, it is possible to improve the situation where the deceleration characteristic required by the automatic brake control unit 16 and the deceleration characteristic actually generated by the deteriorated brake pad are different.

In the fourth embodiment, an example has been described in which only the loosening start timing of automatic brake control is corrected based on the correction value. However, the correction of the start processing timing of the automatic brake control of the fourth embodiment is the correction of the required deceleration characteristics described in the first and second embodiments, that is, the braking force of the automatic brake control. It may be performed in combination with the correction, and / or may be performed in combination with the correction of the braking start timing of the automatic brake control described in the third embodiment.

In the fourth embodiment, the description has been given on the assumption that the start-up process start timing of the automatic brake control is also sequentially changed according to the correction value for which the successive value is changed. However, when the calculation unit 14 determines whether or not the brake pad has deteriorated and determines that the brake pad has deteriorated, control is performed so that the start timing of the automatic brake control loosening process is advanced by a predetermined time. May be. In this case, the determination as to whether or not the brake pads are deteriorated is that the difference is greater than or equal to the threshold value for half of all classes stored in the storage unit 15 in step S906 (FIG. 9) of the second embodiment. Depending on whether or not, it can be considered.

INDUSTRIAL APPLICABILITY The collision avoidance braking device and the collision avoidance braking method according to the present invention can be used for a vehicle or the like having an automatic brake control device. Therefore, it is suitable when the braking start timing and the braking force are always appropriately controlled.

DESCRIPTION OF SYMBOLS 11 Vehicle information acquisition part 12 Obstacle detection part 13 Brake operation detection part 14, 24 Calculation part 15, 25 Storage part 16 Automatic brake control part 51 Brake control part 52 Brake actuator

Claims

A collision avoidance braking device for assisting in avoiding a collision with an obstacle of a vehicle using automatic brake control,
A detection unit for detecting a brake operation by a driver;
An acquisition unit for acquiring a vehicle condition including at least a deceleration of the vehicle;
Correction for estimating the deterioration state of the brake pad from the deceleration of the vehicle acquired at the time of detecting the brake operation and correcting the deceleration of the vehicle at the time of execution of the automatic brake control according to the estimated deterioration state of the brake pad And a collision avoidance braking device.
The detection unit acquires a brake hydraulic pressure at the time of detecting a brake operation,
The correction unit is
A first estimation unit that estimates a deterioration state of a brake pad based on a relationship between the brake hydraulic pressure acquired when the brake operation is detected and the deceleration of the vehicle;
A second estimation unit for estimating an actual deceleration characteristic of the current vehicle based on the estimated deterioration state of the brake pad;
A first calculation unit that calculates a deceleration characteristic required for the vehicle for avoiding a collision in the vehicle condition during the brake operation;
A second calculation unit for calculating a correction value for eliminating a state where the estimated actual deceleration characteristic and the required deceleration characteristic are deviated;
The collision avoidance braking device according to claim 1, further comprising: a control unit that executes the automatic brake control using the correction value.
The correction unit further includes a storage unit that stores the correction values calculated by the second calculation unit by classifying the correction values into a plurality of classes divided according to vehicle conditions at the time of the brake operation,
When the collision avoidance is requested, the control unit reads the correction value classified into the class that matches the vehicle condition at that time from the storage unit, and executes the automatic brake control using the read correction value. The collision avoidance braking device according to claim 2, wherein:
The control unit performs the automatic brake control according to a deceleration characteristic obtained by correcting the required deceleration characteristic calculated by the first calculation unit with the read correction value. The collision avoidance braking device according to claim 3.
4. The collision avoidance braking apparatus according to claim 3, wherein the control unit executes the automatic brake control at a braking start timing obtained by correcting a prescribed braking start timing with the read correction value.
4. The collision according to claim 3, wherein the control unit executes the automatic brake control at a filling process start timing obtained by correcting a prescribed filling process start timing with the read correction value. 5. Avoidance braking device.
The vehicle condition classification includes at least one of a vehicle speed, a vehicle weight, a road gradient, a vehicle outside temperature, a running area weather, and a brake operation frequency. Collision avoidance braking device.
3. The collision avoidance braking device according to claim 2, wherein the first estimation unit does not estimate a deterioration state of the brake pad when the vehicle condition exceeds a predetermined range.
The second calculation unit obtains an average value of a plurality of correction values calculated during a predetermined period, and sets the average value as a correction value used for the automatic brake control. The collision avoidance braking device as described.
A collision avoidance braking method executed by a collision avoidance braking device that assists in avoiding collision of a vehicle with an obstacle using automatic brake control,
A detecting unit detecting a brake operation by the driver;
An obtaining unit obtaining vehicle conditions including at least a deceleration of the vehicle;
A calculation unit estimates a deterioration state of the brake pad from the deceleration of the vehicle acquired when the brake operation is detected, and determines the deceleration of the vehicle at the time of execution of the automatic brake control according to the estimated deterioration state of the brake pad. A collision avoidance braking method.
The detecting step acquires a brake hydraulic pressure at the time of detecting a brake operation,
The correcting step includes
The calculating unit estimating a deterioration state of a brake pad based on a relationship between the brake hydraulic pressure acquired when the brake operation is detected and a deceleration of the vehicle;
The arithmetic unit estimating an actual deceleration characteristic of the current vehicle based on the estimated deterioration state of the brake pad;
The calculating unit calculating a deceleration characteristic required for the vehicle for avoiding a collision in a vehicle condition at the time of the brake operation;
The calculation unit calculating a correction value for eliminating a state where the estimated actual deceleration characteristic and the required deceleration characteristic are deviated; and
The collision avoidance braking method according to claim 10, further comprising: a control unit that executes the automatic brake control using the correction value.