JP2006218993A - Brake assist control method, and brake assist control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brake assist control method, and a brake assist control device capable of improving the determination accuracy of pre-crash control intervention to a driver's brake pedal depressing operation, and realizing adequate pre-crash brake assist (PCBA) to meet the intention (feeling) of the driver. <P>SOLUTION: The timing before the predetermined effective time from the timing forming the reference time of the pre-crash control intervention in which the prediction time of the collision timing between a self vehicle and an obstacle is set is set to be the intervention permissive timing to receive the effective operation of the pre-crash control intervention. The brake pedal depressing operation generated after the intervention permissive timing is received as an effective operation (S2) while the brake pedal stepping-on operation generated before the intervention permissive timing is not received. Thus, the PCBA is intervened even to the brake pedal depressing operation immediately before the reference time while careless intervention of the PCBA is prohibited (S4). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a brake assist control method and a brake assist control device that assist a driver's braking operation and generate a large braking force by depressing a brake pedal.

  In recent years, in vehicles equipped with a so-called collision mitigation braking system, the risk of a collision is predicted from the distance, relative speed, own vehicle speed, etc. with respect to obstacles including the preceding vehicle in front of the own vehicle lane. When it is determined that it can be safely avoided, the driver is warned to that effect, and the brake assist control for braking assistance is used to assist the driver's depression of the brake pedal to avoid a collision.

  Conventionally, the brake assist control includes a normal brake assist (general brake assist (hereinafter, referred to as a general brake assist)) that responds to a sudden brake pedal depressing operation (a depressing amount and a depressing speed at a certain level) for avoiding a collision of a driver. Pre-crash brake assist (hereinafter referred to as PCBA) that actively assists the braking force even by a slight brake pedal operation when a situation in which a collision is inevitable safely) ) Control.

  That is, the brake pedal depression condition in which NBA and PCBA intervene is as shown in FIG. 8, for example, with respect to the depression amount x and the depression speed dx, and the depression amount x in the figure is x2 (xmax (upper limit). )> X1> x2) or more, and when the stepping speed dx (time variation of x, d is a differential operator) is dx2 (dxmax (upper limit)> dx1> dx2) or more, the NBA operates when the stepping amount x is x1 or more. The stepping speed dx is set so that it does not operate unless dx1 or more.

  When it is determined that a collision is inevitable based on the distance (inter-vehicle distance) between the host vehicle and the obstacle measured by a distance measuring sensor such as a laser radar and a change in the time, the brake pedal depression operation lighter than the NBA operation is performed. By operating and intervening, a large assist force is generated, and even if the driver's pedal depression force is not sufficient, the speed of the vehicle at the time of the collision is sufficiently reduced to reduce the damage.

  By the way, when it is difficult to judge the possibility of collision with an obstacle with high accuracy at present due to various causes such as sensor detection performance, output responsiveness, ECU processing capability, road and obstacle positional relationship, etc. There are many.

  The NBA operates with an abrupt depression of the brake pedal as an intervention condition, and the intervention threshold (the threshold of the depression amount x and the depression speed dx) is large. However, PCBA operates with the judgment of the possibility of collision as an intervention condition, and the intervention threshold is set to a small constant value so as to actively assist the driver's brake pedal depression. Therefore, in the current situation where the determination accuracy of the collision possibility is low, the PCBA is not determined based on the erroneous determination of the collision possibility even though the driver depresses the brake pedal with the intention of normal braking without intervention by the brake assist. There is a risk of unexpected intervention and sudden braking.

  With regard to this PCBA, it is proposed that the brake fluid pressure of the brake mechanism is increased as the distance between the vehicle and the obstacle becomes smaller, and the brake assist force is varied in reverse of the short distance between the vehicle and the obstacle. (For example, refer to Patent Document 1).

JP-A-10-297452 (paragraphs [0007], [0042]-[0044], FIGS. 1 and 4)

  In the brake assist control of the conventional proposal (described in Patent Document 1), the brake assist force changes depending on the distance between the vehicle and the obstacle, and the occurrence of sudden braking unintended by the driver is suppressed, but the possibility of collision is high ( Since only the brake pedal depression operation after the timing when the PCBA intervenes is accepted is judged that a collision is inevitable), when the brake pedal depression operation of the driver intended for the PCBA occurs earlier than that timing, The problem that the stepping operation is not accepted, the PCBA does not intervene at the timing that the driver intended, the PCBA control intervention judgment for the brake pedal stepping operation of the driver is low, and an appropriate PCBA according to the driver's intention cannot be realized. There is.

  It is an object of the present invention to improve the accuracy of PCBA control intervention judgment for a driver's brake pedal depression operation, and to realize an appropriate PCBA in accordance with the driver's intention (sense).

  In order to achieve the above-described object, the brake assist control method of the present invention is less than the reference time of the pre-crash control intervention set in the predicted time until the collision timing between the host vehicle and an obstacle such as a preceding vehicle ahead. Sometimes, a brake pedal depressing operation lighter than a depressing operation in which the NBA function is operated is accepted as an effective operation of the pre-crash control intervention, and the PCBA function is activated, and the predicted time becomes the reference time. A timing before a predetermined effective time from the timing is set as an intervention allowable timing for receiving the effective operation, and a brake pedal depression operation that occurs after the intervention allowable timing is received as the effective operation. ).

  Further, the brake assist control method of the present invention operates when the predicted time until the collision timing between the own vehicle and an obstacle such as a preceding vehicle ahead is equal to or less than the set pre-crash control intervention reference time. This is a brake assist control method that activates the PCBA function by accepting a brake pedal depression operation lighter than the depressing operation as an effective operation of the pre-crash control intervention, and is a threshold value in which both the depression amount and the depression speed of the brake pedal are set. The pre-crash control intervention condition for accepting the effective operation is set to be the above, and the threshold value is increased as the timing becomes earlier than the collision timing to make the pre-crash control intervention condition stricter. (Claim 2).

  Furthermore, the brake assist control method according to the present invention operates when the predicted time until the collision timing between the host vehicle and an obstacle such as a preceding vehicle ahead falls below the set pre-crash control intervention reference time. A brake assist control method that activates a PCBA function by accepting a brake pedal depression operation lighter than a depressing operation as an effective operation of the pre-crash control intervention, and a predetermined effective time from a timing at which the predicted time becomes the reference time The pre-crash control intervention condition for accepting the effective operation is that the previous timing is set as the permissible intervention timing for accepting the effective operation and that both the brake pedal depression amount and the depression speed are equal to or greater than the set threshold values. And at least one of the thresholds is set to the collision The pre-crash control intervention condition is tightened by increasing the timing before imming, and only brake pedal depression operations that occur after the intervention permissible timing and that exceed the threshold are accepted as the effective operations. (Claim 3).

  Next, the brake assist control device according to the present invention has the NBA function when the predicted time until the collision timing between the own vehicle and an obstacle such as a preceding vehicle ahead becomes equal to or less than the set pre-crash control intervention reference time. A brake assist control device that accepts a brake pedal stepping operation lighter than an operating stepping operation as an effective operation of the pre-crash control intervention and activates a PCBA function of the brake mechanism, and a distance measurement result of a distance measurement sensor mounted on the own vehicle A collision prediction means for detecting a time change in the distance between the host vehicle and the obstacle and calculating the collision prediction time repeatedly, and a timing before a predetermined effective time from the timing at which the prediction time becomes the reference time A brake pedal that is set to an intervention allowable timing for receiving an effective operation and that occurs after the intervention allowable timing. Valid operation accepting means for accepting a swallowing operation as the valid operation, and brake mechanism control means for operating the PCBA function of the brake mechanism after the reference time based on the valid operation accepted by the valid operation accepting means; (Claim 4).

  In the brake assist control device of the present invention, the NBA function operates when the predicted time of the collision timing between the own vehicle and an obstacle such as a preceding vehicle ahead is equal to or less than the set pre-crash control intervention reference time. A brake assist control device that accepts a brake pedal depression operation that is lighter than the depression operation as an effective operation of the pre-crash control intervention, and activates the PCBA function of the brake mechanism, from the distance measurement result of the distance measurement sensor mounted on the own vehicle Collision prediction means that repeatedly calculates the collision prediction time by detecting temporal changes in the distance between the host vehicle and the obstacle, and at least one of the depression amount and depression speed of the brake pedal as a pre-crash control intervention condition The pre-crash becomes larger as the threshold becomes earlier than the collision timing. Effective operation receiving means that is variably set so that the control intervention condition becomes severe, and that the brake pedal depression operation when both the depression amount and the depression speed are equal to or more than the threshold value is received as the effective operation; and the effective operation reception Brake mechanism control means for operating the PCBA function of the brake mechanism after the timing of the reference time based on the effective operation received by the means (Claim 5).

  Furthermore, the brake assist control device according to the present invention operates when the predicted time until the collision timing between the own vehicle and an obstacle such as a preceding vehicle ahead is equal to or less than the set pre-crash control intervention reference time. A brake assist control device that accepts a brake pedal depression operation that is lighter than the depressing operation as an effective operation of the pre-crash control intervention and activates the PCBA function of the brake mechanism, and the distance measurement result of the distance measurement sensor mounted on the own vehicle A collision prediction means for detecting a time change in the distance between the host vehicle and the obstacle and calculating the collision prediction time repeatedly, and a timing before a predetermined effective time from the timing at which the prediction time becomes the reference time Brake is set as an intervention-acceptable timing for accepting valid operations and pre-crash control intervention conditions The threshold value of at least one of the stepping amount of the dull and the stepping speed is variably set so that the pre-crash control intervention condition becomes severe as the timing before the collision timing becomes severe, and the intervention allowable timing Effective operation accepting means for accepting only the operation of the brake pedal depressing operation that has occurred since then both the depressing amount and the depressing speed are both equal to or greater than the threshold value as the effective operation, and the effective operation accepting means Brake mechanism control means for operating the PCBA function of the brake mechanism after the timing of the reference time based on an effective operation is provided (claim 6).

  According to the first and fourth aspects of the present invention, if a brake pedal depression operation intended for PCBA occurs before the reference time of pre-crash control intervention, this occurrence is after the intervention allowable timing. On the condition that the operation is accepted as a brake pedal depressing operation intended for PCBA intervention, and a brake pedal depressing operation immediately before the reference time, which the driver intends to perform PCBA intervention, becomes the reference time. PCBA can be intervened.

  On the other hand, the brake pedal depressing operation that occurred before the intervention allowable timing is usually an operation that the driver does not intend to intervene in the PCBA. Can be prevented and prevented.

  Therefore, by setting the above-described intervention permissible timing, the accuracy of the PCBA control intervention judgment with respect to the driver's brake pedal depression operation can be improved, and an appropriate PCBA in accordance with the driver's intention (sense) can be realized.

  Next, according to the configurations of claims 2 and 5, both threshold values of the depression amount and the depression speed of the brake pedal are set as the threshold values of the pre-crash control intervention condition, and these threshold values are predicted. It becomes so large that it becomes the timing before the made collision timing, and it becomes difficult to intervene PCBA.

  Therefore, even before the timing of the reference time is reached, that is, before the PCBA intervenes, the brake pedal depressing operation exceeding the new value is a brake pedal depressing operation intended for the PCBA intervention. As a result, the PCBA can be intervened even when the driver depresses the brake pedal immediately before the reference time, which is intended by the driver to intervene.

  On the other hand, when the timing is much earlier than the timing of the reference time, the threshold value becomes sufficiently large, and PCBA hardly intervenes depending on the previous depression of the brake pedal, and the PCBA is performed without intention. By not accepting the depression of the brake pedal, careless PCBA intervention can be prohibited and prevented.

  Therefore, by setting the threshold value, the accuracy of the PCBA control intervention determination with respect to the driver's brake pedal depression operation is improved, and an appropriate PCBA in accordance with the driver's intention (sense) can be realized.

  Next, according to the configuration of claims 3 and 6, even if the brake pedal depression operation that occurred before the timing of the reference time for the pre-crash control intervention, the operation occurred after the intervention allowable timing, If the operation is equal to or greater than the threshold value, the operation is accepted as a brake pedal depression operation intended for PCBA, and PCBA intervenes.

  At this time, the earlier the brake pedal depressing operation is performed, the greater the threshold value becomes, and the more difficult the PCBA is to intervene, and the brake pedal depressing operation before the intervention allowable timing is PCBA intervention is prohibited.

  Therefore, based on the combination of the intervention allowable timing setting and the variable threshold value, the PCBA control for the driver's brake pedal depression operation is performed such that the PCBA does not intervene by a normal brake pedal depression operation. The accuracy of intervention determination can be further improved, and a very appropriate PCBA that matches the driver's intention (sense) can be realized.

Next, in order to describe the present invention in more detail, an embodiment thereof will be described in detail with reference to FIGS.
<First Embodiment>
First, a first embodiment will be described with reference to FIGS.

  FIG. 1 is a block diagram of a brake assist control device for a vehicle (own vehicle) 1, FIG. 2 is a hydraulic system diagram of a brake mechanism of the brake control unit of FIG. 1, and FIGS. 3 and 4 are flowcharts for explaining the operation of FIG. FIG. 5 is a waveform diagram for explaining the operation of FIG.

  The control ECU 2 of the microcomputer configuration of the brake assist control device of FIG. 1 is a sensor of the vehicle 1 such as a vehicle speed sensor 3, a distance measuring sensor 4, a throttle opening sensor 5, and a brake sensor 6 after the engine of the vehicle 1s is started. Collect the detection signal every moment.

  The vehicle speed sensor 3 is a so-called wheel speed sensor, and detects the rotation of the wheel of the host vehicle 1 and outputs a detection signal of the host vehicle speed.

  The distance measuring sensor 4 includes a laser radar, a monocular camera, and the like that searches and captures the front of the host vehicle 1, and detects obstacles in front of the vehicle 1 and the preceding vehicle by detecting a difference in transmission / reception time of laser pulses and processing captured images. The distance is measured and the measurement signal is output.

  Next, the brake sensor 6 includes, for example, a brake switch and a hydraulic pressure sensor for the brake unit 7. The brake pressure (hydraulic pressure) is detected as a signal indicating whether or not the brake pedal is depressed, and the detection amount x and the depression speed dx. Pressure) signal.

  Next, the control ECU 2 includes the following software processing means (a1) to (a3) by executing the brake assist control program shown in the flowcharts of FIGS.

(A1) Collision prediction means This means is a prediction time by moment to the collision timing (hereinafter referred to as collision prediction time TTC) based on the measurement distance of the distance measuring sensor 4 and its change over time, for example, a solid line a in FIG. The collision prediction time TTC every moment that changes with the above characteristic is repeatedly calculated.

  Specifically, for example, the distance and relative speed between the host vehicle 1 and the front obstacle such as the preceding vehicle are detected every moment from the measured distance of the distance measuring sensor 4 and the detected host vehicle speed of the vehicle speed sensor 3. The predicted collision time TTC is calculated every moment from the time when the vehicle 1 and the obstacle are in contact with each other by traveling the detection distance at the relative speed.

  The predicted collision time TTC becomes smaller (shorter) as the host vehicle approaches the obstacle, and when the host vehicle speed relative to the obstacle is a relative speed, the higher the relative speed is.

  In addition, instead of obtaining the predicted collision time TTC by the above calculation, a value corresponding to the detected relative speed and measured distance is read from a map of the predicted predicted time TTC at each measured distance for each relative speed set in advance. You may ask for it.

(A2) Effective operation accepting means This means includes a reference time Tr of pre-crash control intervention for determining how much time the predicted time TTC is before the collision timing and operating the PCBA to intervene. A predetermined effective time T1 for determining how far the brake pedal depressing operation before the timing of the reference time Tr is accepted as an effective operation of the PCBA intervention is set in advance, and the effective time from the timing of the reference time Tr The timing before T1 is set as an intervention allowable timing for accepting the effective operation, and a brake pedal depression operation that occurs after the intervention allowable timing is accepted as the effective operation.

  Specifically, every time the brake pedal depression operation of the host vehicle 1 occurs, the software timer is started to start timing, and for example, the predicted collision time TTC from the predicted collision timing te in FIG. When the characteristic indicated by the solid line a is shorter, the timing t3 in the figure when the predicted time TTC becomes the reference time Tr, and the intervention allowable timing tl in the figure before the effective time T1 from the timing t3 are detected in the order of the timings tl and t3. Then, a brake pedal depressing operation with a certain depressing amount x and depressing speed dx or more after the intervention allowable timing tl is detected and accepted as an effective operation.

  In this case, even if the brake pedal depressing operation is lighter than the NBA intervention depressing operation, the predetermined depressing amount x and the depressing speed dx are, for example, the depressing amount x2, The stepping speed dx2 is set, and the pedal depression operation of the depression amount x2 and the depression speed dx2 or higher becomes the detection pedal depression operation.

  Note that the reference time Tr is, for example, a few seconds calculated at a standard timing t3 at which it is expected that the driver in the collision risk area D2 in FIG. The following time is set based on experiments and the like.

  Further, the valid time T1 is the time from the intervention allowable timing tl in FIG. 5 to the timing t3, which is before the timing t3 in the collision risk area D2 and the driver may step on the brake pedal with the intention of the PCBA intervention. This is a unit time, and this time T1 is also set based on experiments or the like.

  Further, D1 in FIG. 5 is a normal operation region where the predicted collision time TTC is sufficiently long (long) and the possibility of collision is low, and is a region where the NBA intervenes only by a sudden depression of the brake pedal.

  In FIG. 5, t1 is a normal brake pedal depressing operation generation timing in the normal operation region D1, t2 is a brake pedal depressing operation generation timing within an effective time T1 intended for PCBA intervention, and t4 is further approached after the timing t3. It is the timing when the brake pedal depressing operation occurs in the state.

  When the collision prediction time TTC is reduced to the reference time Tr, as shown by the solid line b in FIG. 5, the PCBA intervention standby flag of the effective operation detecting means is set from 0 to 1, and the control ECU 2 Thus, a PCBA intervention command is output.

  Therefore, the valid operation accepting means intends not only for the brake pedal depression operation that occurred at timing t4 after timing t3 in FIG. 5 but also for the PCBA intervention at timing t2 in FIG. 5 that occurred before the valid time T1 from timing t3. The brake pedal depressing operation is also accepted as a driver's brake pedal depressing operation (effective operation) intended for PCBA intervention.

(A3) Brake mechanism control means This means instructs the brake unit 7 to perform PCBA intervention after timing t3 based on the effective operation of PCBA intervention received by the effective operation detection means, and activates the PCBA function of the brake mechanism.

  That is, the PCBA intervention standby flag is set from 0 to 1 at timing t3 in FIG. 5 and the control ECU 2 enters a state of outputting a PCBA intervention command. For example, in response to the brake pedal depression operation at timing t2 in FIG. Outputs a PCBA intervention command at timing t3, outputs a PCBA intervention command at time t4 ′ immediately after the depression of the brake pedal at timing t4, and at timing t2 that occurred before the effective time T1 from timing t3. PCBA is also intervened by depressing the brake pedal.

  On the other hand, the brake pedal depressing operation before the intervention allowable timing tl is sufficiently earlier than the timing t3 and the predicted collision time TTC is large, and it is determined that the driver does not intend the PCBA intervention. No command is generated and the PCBA function is disabled.

  Next, the brake assist control device of FIG. 1 includes a brake unit 7 as a brake mechanism that operates in response to the PCBA intervention command and the NBA intervention command output from the control ECU 2, an alarm unit 8 that performs a collision alarm, and a throttle control unit. 9 Other various control units are also provided.

  Then, for example, when the vehicle 1 approaches the obstacle, the alarm unit 8 notifies the driver of a collision inevitable alarm by a buzzer sound, a lamp point, or a voice output of a message or a character display, and steps on the brake pedal. In some cases, NBA intervention and PCBA intervention are also notified to the driver by a buzzer sound, a ramp point, or the like.

  Next, the brake mechanism of the brake unit 7 will be described with reference to FIG.

  The brake unit 7 includes a microcomputer-structured brake ECU 70 and a hydraulic pump type brake mechanism (actuator) operated by the ECU 70. The brake ECU 70 operates according to the NBA intervention command and PCBA intervention command of the control ECU 2 in FIG. Control the mechanism.

  The front and rear wheel parts on the right side of the brake mechanism and the front and rear wheel parts on the left side have the same structure, for example, the front and rear wheel parts on the right side are configured as shown in FIG. The brake ECU 70 similarly controls the right front and rear wheel portions and the left front and rear wheel portions.

  A master cylinder 73 is connected to the brake pedal 71 via a brake booster 72, and a reservoir tank 74 that stores brake fluid (brake oil) is connected to the master cylinder 73.

  Further, a hydraulic pressure path 701 as an upstream inflow trunk path is connected to the master cylinder 73, and the brake hydraulic pressure corresponding to the depression force of the brake pedal 71 of the driver linearly passes through the hydraulic pressure path 701 as the master cylinder pressure. The amount of opening and closing of the upstream valve 702 is controlled by the ECU 70.

  Then, during the normal operation in which the predicted collision time TTC is the time of the normal operation region D1 in FIG. 5, the normal depression operation of the brake pedal 71 in which the master cylinder pressure becomes lower than the set pressure Pr, for example, the brake at the timing t1 in FIG. When the pedal depression operation occurs, the master cylinder pressure is directly increased from the hydraulic pressure path 703 as the downstream inflow trunk path through the inflow side connection point α, branched front and rear branch paths 704F and 704R. To the downstream valves 705F and 705R on the front input side and the rear input side, and further to the wheel cylinder 11F on the front wheel 10F and the wheel cylinder 11R on the rear wheel 10R via the front and rear branch paths 706F and 706R. The braking pressure changes as shown by a solid line # 3 in FIG. 5, and the vehicle 1 is driven by a braking force corresponding to the depression pressure of the brake pedal 71. To stop (stop).

  The front output and rear downstream valves 708F and 708R, which are pressure reducing valves, are connected to the branch paths 706F and 706R via the front and rear branch paths 707F and 707R. The downstream valves 708F and 708R are brake brakes. Before the control, it is held open, and is closed during normal brake control and NBA / PCBA brake control, and is opened and closed during automatic brake control in automatic operation or the like.

  In addition, front and rear branch paths 709F and 709R are connected to the downstream valves 708F and 708R, and both branch paths 709F and 709R are coupled at one end of a hydraulic pressure path 710 as an outflow trunk path. The other end is connected to the suction path 712 of the hydraulic pump 711 of the pressurizing mechanism via the outflow side connection point β.

  Furthermore, the pressure path 714 on the discharge side of the pump 711 driven by the motor 713 is connected to the inflow side connection point α by providing a check valve 715, an accumulator 716, and a pressure switch 717 in order from the pump 711 side. Furthermore, a pressurized liquid supply path 718 is provided between the end of the hydraulic path 701 on the master cylinder 73 side and the outflow side connection point β, and a switching valve in order from the hydraulic path 701 side is provided in this path 718. An upstream valve 719 and a check valve 720 are provided.

  The check valve 715 prevents the backflow from the inflow side connection point α to the pump 711, and the check valve 720 prevents the backflow from the outflow side connection point β to the path 718.

  Reference numerals 721 and 722 in FIG. 2 denote pressure switches for the hydraulic pressure path 701 and the pressurization path 714, which form the brake sensor 6 in FIG. 1, detect the master cylinder pressure and the brake assist pressure, and display the detected pressure signals. 1 and the ECU 70 in FIG.

  Then, when the driver depresses the brake pedal 71 suddenly at a stepping amount x1 or more and a stepping speed dx1 or more during normal operation, for example, when the driver depresses the brake pedal 71, the master cylinder pressure becomes the NBA intervention reference value in a very short time. The pressure is increased to the set pressure Prn, and from this pressure increase to the set pressure Prn, the ECU 2 detects a brake pedal depression operation of x ≧ x1 and dx ≧ dx1, and instructs the ECU 70 to perform NBA intervention. Based on this command, the ECU 70 The intervention control is executed, the motor 713 is driven, and the upstream valve 719 is opened.

  At this time, the brake fluid for assist pressurization is sent from the reservoir tank 74 to the hydraulic pump 711 via the master cylinder 73 and the path 718, and the NBA function is activated, and NBA is discharged by the discharge of the hydraulic pump 711 and the accumulated pressure of the accumulator 716. When this assist pressure reaches a set level, the upstream valve 719 is closed.

  Therefore, during a normal operation with a long predicted collision time TTC, when the driver suddenly depresses the brake pedal, a constant control pressure is added to the master cylinder pressure, and a large control pressure of the master cylinder pressure + the assist pressure is It is transmitted from the inflow side connection point α to the wheel cylinders 11F and 11R through the downstream valves 705F and 705R, and a larger deceleration is generated than in the case of only the master cylinder pressure, and the own vehicle 1 is quickly stopped.

  Next, when the collision prediction time TTC becomes equal to or shorter than the reference time Tr for pre-crash control intervention in FIG. 5, the ECU 2 enters the PCBA intervention command output state as described above.

  Then, after the intervention allowable timing tl before the effective time T1 from the timing t3 when the pre-crash intervention reference time Tr is reached, the driver depresses the brake pedal 71, for example, the depression amount x2 or more, for example, with the intention of the PCBA intervention. Depressing at a speed dx2 or higher and when the master cylinder pressure is increased to the PCBA intervention reference set pressure Prp (<Prn), the ECU 2 detects an effective operation of x ≧ x2 and dx ≧ dx2 from the increase to the set pressure Prp. The ECU 2 instructs the ECU 70 to perform PCBA intervention immediately after detection for the effective operation after the timing t3 for the effective operation, and the ECU 70 executes the control of the PCBA intervention based on the command. Then, the motor 713 is driven and the upstream valve 719 is opened, and the reservoir tank 74 Tashirinda 73, the brake fluid of the assist pressurizing the hydraulic pump 711 via path 718 is sent PCBA function is activated.

  At this time, the discharge pressure of the hydraulic pump 711 and the accumulated pressure of the accumulator 716 form an assist pressure of PCBA higher than the assist of the NBA, and the upstream valve 719 is closed. For example, as shown by solid lines # 1 and # 2 in FIG. The own vehicle 1 decelerates and stops due to a large master cylinder pressure + braking pressure (control pressure) having a large assist pressure.

  The above operation will be described with reference to the flowcharts of FIGS. 3 and 4. First, the collision prediction means calculates the momentary collision prediction time TTC in step S1 in FIG. 3, and in step S2, the collision prediction time. The size (long or short) of the TTC and the reference time Tr is determined.

  Here, when TTC> Tr before timing t3, the process proceeds to step S3 through the determination in step S2, and if a sudden brake pedal depression operation intended for NBA intervention occurs, this is accepted and step The process proceeds from step S3 to step S4, where the ECU 2 outputs an NBA intervention command to the unit 7 and operates the NBA to intervene.

  Further, when TTC <Tr after timing t3, the process proceeds to step S5 through the determination of step S2, and when a brake pedal depression operation intended for PCBA intervention occurs, this is accepted and the process proceeds from step S5 to step S5. In step S6, the ECU 2 outputs a PCBA intervention command to the unit 7 and operates the PCBA to intervene.

  Next, at the timing t3 of TTC = Tr, the process proceeds from step S2 to step S7 in FIG. 3, and the brake pedal to be detected that intends the intervention of PCBA from this timing t3 to the intervention allowable timing tl before the effective time T1. It is determined whether or not there has been a stepping operation (whether or not it has been accepted).

  Then, when there is a corresponding operation, the process proceeds from step S7 to step S6, the ECU 2 outputs a PCBA intervention command to the unit 7, and activates the PCBA at time t3 to intervene.

  By the way, the determination in step S7 is made when the valid operation accepting means detects and accepts a valid operation as shown in FIG.

  That is, the valid operation acceptance / reception means initially detects the valid operation flag fop for detecting the valid operation and the brake operation counter tbrk for timing in step Q1 in FIG. 4 and then detects them in a loop of steps Q2 and Q3. The occurrence of the target brake operation is monitored, and when this brake operation occurs, the process proceeds from step Q3 to step Q4 and the flag fo is set to 1.

  Further, the process proceeds from step Q4 to step Q5, and the time of the counter tbrk is incremented by +1 (unit time increment). Thereafter, until the counter tbrk times the valid time T1, the steps of steps Q6, Q2, Q7, Q4, Q5, Q6 are performed. As a result of the loop operation, the counter tbrk is incremented by +1.

  If the brake operation is after the intervention allowable timing tl, the counter tbrk reaches the timing t3 until the effective time T1 is counted, and at this time, the presence or absence of acceptance of the effective operation is confirmed from the counters fo 1 and 0. It is determined whether or not the detection target brake pedal depression operation (effective operation) has been performed.

  On the other hand, if the operation is before the intervention allowable timing tl, the counter tbrk measures the valid time T1 before the timing t3. At this time, the process moves from step Q6 to step Q8, and the counter fop, tbrk is reset to 0 and PCBA does not intervene.

  Then, by returning from steps Q6 and Q9 to step Q2, the detection of the brake operation to be detected is repeated.

  Therefore, in the case of this embodiment, the brake after the timing t3 when the predicted collision time TTC becomes shorter than the reference time Tr of the pre-crash control intervention and it is determined that the collision between the own vehicle 1 and the obstacle cannot be safely avoided. Not only the pedal depression operation but also the brake pedal depression operation from the timing t3 to the intervention allowable timing tl before the effective time T1 is judged to be an operation intended for the PCBA intervention, the PCBA is intervened, and the master cylinder pressure + assist The host vehicle 1 can be decelerated and stopped by a large control pressure to reduce damage.

  At that time, since the PCBA intervenes even when the brake pedal is depressed lighter than the NBA intervention, even if the driver cannot fully depress the brake pedal 71 for some reason, the driver's intention to intervene in the PCBA is taken in and the PCBA is intervened. Can do.

  On the other hand, for the brake pedal depressing operation before the intervention allowable timing tl, the predicted collision time TTC is sufficiently long, so that the PCBA does not intervene accidentally by a brake pedal depressing operation lighter than the NBA intervention. Can do.

  Therefore, the PCBA intervention determination accuracy for the driver's brake pedal depression operation is improved, and appropriate control intervention in accordance with the driver's intention (sense) can be realized.

<Second Embodiment>
Next, a second embodiment will be described with reference to FIGS. 1, 6, and 7.

  FIGS. 6 and 7 are flowcharts and waveform diagrams for explaining the operation. The brake assist control device of this embodiment is also configured almost as shown in FIG. 1, but the control ECU 2 of FIG. By executing the illustrated brake assist control program, it differs from the first embodiment in that the following effective operation receiving means is provided instead of the effective operation receiving means of the first embodiment.

  The valid operation accepting means of the second embodiment is set to the intervention allowable timing tl for accepting the valid operation at a timing just before the valid time T1 from the timing t3 at which the predicted collision time becomes the reference time Tr, and As the pre-crash control intervention condition, the threshold value xs, dxs of at least one of the brake pedal depression amount x and the depression speed dx increases as the timing comes before the collision timing te, and the pre-crash control intervention condition becomes larger. Only the operation which is variably set so as to be severe and the brake pedal is depressed after the intervention allowable timing tl and at least one of the depression amount x and the depression speed dx is greater than or equal to the threshold values xs and dxs is effective. Accept as an operation.

  That is, the threshold value xs, dxs of at least one of the brake pedal depression amount x and the depression speed dx as the pre-crash control intervention condition is set before the collision timing te. At least one of a stepping amount x and a stepping speed dx, which is a function of variably setting so that the pre-crash control intervention condition becomes stricter as the timing becomes, and a brake pedal stepping operation occurring after the intervention allowable timing tl And a function of detecting an operation in which one of the thresholds xs and dxs is exceeded, and a brake pedal depressing operation occurring after the intervention allowable timing tl, and at least one of the depressing amount and the depressing speed is a threshold xs, dxs or higher operation Only this operation is the effective operation. It is that to accept.

  In this embodiment, in order to improve control accuracy and the like, as shown in FIG. 7, the threshold values xs and dxsx are set to the minimum at the collision timing te as the timing comes before the collision timing te. When it is variably set so that the pre-crash control intervention condition becomes stricter than the values xmin and dxmin, and both of the stepping amount x and the stepping speed dx are greater than or equal to the threshold values xs and dxs after the intervention allowable timing tl. The brake pedal depressing operation is accepted as an effective operation.

  The threshold values xs and dxs may be linear change characteristics in which, for example, the collision prediction time TTC is approximately the stepping amount x2 and the stepping speed dx2 at the timing t3 of the reference time Tr. If the change characteristic is such that the brake pedal depression operation after the intervention allowable timing tl is accepted as much as possible as the operation of PCBA intervention, and the brake pedal depression operation before the intervention allowable timing tl is not accepted as much as possible as the operation of PCBA intervention. Well, it is not limited to linear change characteristics.

  The threshold values xs and dxs may be increased as the timing goes back from the timing te with reference to the minimum values xmin and dxmin at the collision timing te. The values xs and dxs may be used as a reference so as to decrease as the collision timing te is approached.

  As the threshold values xs and dxs change, the pre-crash control intervention condition (brake pedal condition) becomes larger and more severe as the collision prediction time TTC becomes longer, as shown by the solid line # 4 in FIG. PCBA is less likely to intervene.

  Next, a specific operation will be described. As shown in FIG. 6, when the collision prediction means calculates the collision prediction time TTC and predicts the collision timing te in step R1, the operation proceeds to step R2 and the valid operation accepting means operates. From the table of threshold values xs and dxs at each timing that goes back by time, the threshold values xs and dxs at the corresponding timing are read out and set variably.

  Further, before the timing t3 (TTC <Tr), the effective operation accepting means determines that the stepping amount x and the stepping speed dx detected from, for example, a change in braking pressure, in step R3, based on the occurrence of the brake pedal stepping operation, x ≧ It is determined whether or not the stepping operation is x1 and dx ≧ dx1, and if the stepping operation is x ≧ x1 and dx ≧ dx1, an NBA intervention command is output to the ECU 70 in FIG. Intervene.

  On the other hand, after timing t3 (TTC ≦ Tr), the process proceeds from step R3 to step R5, and in this step R5, as in the case of the first embodiment, timings t3 (TTC = Tr) and later than t3. The process is divided into (TTC <Tr).

  Then, at timing t3 (TTC = Tr), whether or not the brake pedal depressing operation of x ≧ xs and dx ≧ dxs has occurred between the intervention allowable timing tl and t3 before the effective time T1. If there is a stepping operation of x ≧ xs and dx ≧ dxs, it is accepted and the process proceeds to step R6, and a PCBA intervention command is output to the ECU 70 to intervene PCBA.

  Further, after t3 (TTC <Tr), every time the brake pedal depression operation occurs, it is determined whether or not x ≧ xs and dx ≧ dxs, and x ≧ xs and dx ≧ dxs. If it is a stepping-in operation, it will be accepted and it will transfer to step R6, a PCBA intervention command will be output to ECU70, and PCBA will be intervened.

  At this time, the threshold values xs and dxs increase and the PCBA becomes difficult to intervene before the collision timing te, and the PCBA actively intervenes by a light brake pedal depressing operation after the timing t3, and the timing t3 Before that, the PCBA performs the brake pedal depression operation to a certain extent so as to accept only the operation intended for the PCBA intervention.

  In addition, erroneous intervention of the PCB is reliably prevented by the depression of the brake pedal before the intervention allowable timing tl.

  Therefore, in this embodiment, based on the combination of the setting of the permissible intervention timing tl and the variable of the threshold values xs and dxs, the driver does not intervene in the normal brake pedal depressing operation, and the driver depresses the brake pedal. It is possible to further improve the accuracy of the PCBA control intervention judgment for the operation, and to realize a very appropriate PCBA according to the driver's intention (sense).

  Even if one of the threshold values xs and dxs is varied, the PCBA intervention is limited in the same manner as described above, and the same effect can be obtained.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention.

  For example, the control ECU 2 in FIG. 1 includes effective operation receiving means having the following configuration instead of the effective operation receiving means of the first and second embodiments, and variably setting at least one of the threshold values xs and dxs. The same effects as those of the two embodiments may be achieved.

  In other words, the effective operation acceptance means is set so large that the threshold value xs, dxs of at least one of the brake pedal depression amount x and the depression speed dxs as the pre-crash control intervention condition becomes a timing before the collision timing te. Thus, the brake pedal depression operation when the pre-crash control intervention condition is variably set so that at least one of the depression amount x and the depression speed dxs becomes equal to or higher than the threshold values xs and dxs is accepted as the effective operation. In this configuration, after the timing t3, the PCBA actively intervenes by a light brake pedal depression operation, and before the timing t3, only the operation intended for the PCBA intervention may be accepted. PC for brake pedal depressing operation Improved intervention decision accuracy of A, it is possible to achieve appropriate control interventions in line with the driver's intention (sensory).

  Of course, the reference time Tr, the effective time T1, the threshold values xs, dxs, and the like may be appropriately set according to the vehicle type and the like.

  By the way, in order to reduce the number of equipment parts of the own vehicle 1, for example, the present invention can be applied to the case where the vehicle speed sensor 3 and the distance measuring sensor 4 of FIG.

It is a block diagram of a 1st embodiment of this invention. It is a detailed block diagram of the brake mechanism of the brake unit of FIG. It is a flowchart for operation | movement description of FIG. It is a flowchart for operation | movement description of FIG. It is a wave form diagram for operation | movement description of FIG. It is a flowchart of 2nd Embodiment of this invention. It is a wave form diagram of 2nd Embodiment of this invention. It is explanatory drawing of the brake assist intervention condition of a prior art example.

Explanation of symbols

1 Vehicle 2 Control ECU
4 Distance sensor 7 Brake unit 71 Brake pedal

Claims (6)

Stepping on the brake pedal that is lighter than the stepping operation in which the normal brake assist function operates when the estimated time until the collision timing between the vehicle and the preceding preceding vehicle is below the set reference time for pre-crash control intervention A brake assist control method that accepts an operation as an effective operation of the pre-crash control intervention and activates a pre-crash brake assist function,
A timing before a predetermined effective time from the timing at which the predicted time becomes the reference time is set as an intervention allowable timing for receiving the effective operation,
A brake ast control method, wherein a brake pedal depression operation occurring after the intervention allowable timing is received as the effective operation. Stepping on the brake pedal that is lighter than the stepping operation in which the normal brake assist function operates when the estimated time until the collision timing between the vehicle and the preceding preceding vehicle is below the set reference time for pre-crash control intervention A brake assist control method that accepts an operation as an effective operation of the pre-crash control intervention and activates a pre-crash brake assist function,
The pre-crash control intervention condition for accepting the effective operation is to set both the brake pedal depression amount and the depression speed to be equal to or greater than the set threshold value,
In addition, the brake assist control method is characterized in that the pre-crash control intervention condition is made stricter by increasing the threshold as the timing before the collision timing. Stepping on the brake pedal that is lighter than the stepping operation in which the normal brake assist function operates when the estimated time until the collision timing between the vehicle and the preceding preceding vehicle is below the set reference time for pre-crash control intervention A brake assist control method for accepting an operation as an effective operation of the pre-crash control intervention and operating a pre-crash brake assist function,
A timing before a predetermined effective time from the timing at which the predicted time becomes the reference time is set as an intervention allowable timing for receiving the effective operation,
The pre-crash control intervention condition for accepting the effective operation is to set both the brake pedal depression amount and the depression speed to be equal to or greater than the set threshold value,
And, at least one of the threshold values is increased so as to be a timing before the collision timing, and the pre-crash control intervention condition is made stricter,
A brake assist control method, wherein only a brake pedal depression operation that has occurred after the intervention allowable timing and that is equal to or greater than the threshold value is accepted as the effective operation. Stepping on the brake pedal that is lighter than the stepping operation in which the normal brake assist function operates when the estimated time until the collision timing between the vehicle and the preceding preceding vehicle is below the set reference time for pre-crash control intervention A brake assist control device that accepts an operation as an effective operation of the pre-crash control intervention, and activates a pre-crash brake assist function of the brake mechanism,
A collision prediction means for detecting the time change of the distance between the vehicle and the obstacle from a distance measurement result mounted on the vehicle and repeatedly calculating the collision prediction time;
A timing before a predetermined effective time from the timing at which the predicted time becomes the reference time is set as an allowable intervention timing for accepting the effective operation, and an effective operation for accepting a brake pedal depression operation occurring after the allowable intervention timing as the effective operation. Operation accepting means;
Brake assist control comprising: brake mechanism control means for operating the pre-crash brake assist function of the brake mechanism after the timing of the reference time based on the valid operation received by the valid operation accepting means. apparatus. Brake pedal depressing operation that is lighter than the normal depressing operation that activates the brake assist function when the predicted time of collision timing between the host vehicle and the obstacle ahead such as the preceding vehicle falls below the set pre-crash control intervention reference time A brake assist control device that accepts the pre-crash control intervention as an effective operation and operates the brake assist function of the pre-crash of the brake mechanism,
A collision prediction means for detecting the time change of the distance between the vehicle and the obstacle from a distance measurement result mounted on the vehicle and repeatedly calculating the collision prediction time;
The threshold value of at least one of the brake pedal depression amount and the depression speed as the pre-crash control intervention condition becomes larger as the timing before the collision timing becomes so that the pre-crash control intervention condition becomes stricter. An effective operation receiving means that is variably set and receives a brake pedal depression operation as the effective operation when both the depression amount and the depression speed are equal to or greater than the threshold value;
Brake assist control comprising: brake mechanism control means for operating the pre-crash brake assist function of the brake mechanism after the timing of the reference time based on the valid operation received by the valid operation accepting means. apparatus. Stepping on the brake pedal that is lighter than the stepping operation in which the normal brake assist function operates when the estimated time until the collision timing between the vehicle and the preceding preceding vehicle is below the set reference time for pre-crash control intervention A brake assist control device that accepts an operation as an effective operation of the pre-crash control intervention and activates a pre-crash brake assist function of the brake mechanism,
A collision prediction means for detecting a time change in the distance between the vehicle and the obstacle from a distance measurement result of a distance sensor mounted on the vehicle and repeatedly calculating the collision prediction time;
A timing before a predetermined effective time from the timing at which the predicted time becomes the reference time is set as an intervention permissible timing for receiving the effective operation, and at least a brake pedal depression amount and a depression speed as a pre-crash control intervention condition One of the threshold values is variably set so that the pre-crash control intervention condition becomes stricter as the timing before the collision timing becomes severe, and the brake pedal depressing operation generated after the intervention allowable timing is set. Valid operation accepting means for accepting only an operation in which both the stepping amount and the stepping speed are both equal to or greater than the threshold value as the valid operation;
Brake assist control comprising: brake mechanism control means for operating the pre-crash brake assist function of the brake mechanism after the timing of the reference time based on the valid operation received by the valid operation accepting means. apparatus.

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