阅读说明：本技术 车辆控制装置 (Vehicle control device ) 是由 间濑祐介 稻叶祥一 森和辉 于 2020-04-09 设计创作，主要内容包括：本发明提供一种车辆控制装置,其具备目标检测传感器和控制致动器的工作的控制装置。目标检测传感器检测位于可检测区域的目标相对于该车辆的相对速度,且在目标存在于近距离区域的情况下无法检测相对速度。控制装置算出相对速度的每单位时间的变化量(时间变化率),在目标进入到近距离区域的情况下,基于从最后从目标检测传感器取得目标的相对速度的时刻即最终取得时刻起到当前时刻为止的经过时间、最终取得时刻的目标的相对速度即最终取得相对速度及时间变化率,算出推定相对速度。(The invention provides a vehicle control device, which comprises a target detection sensor and a control device for controlling the operation of an actuator. The object detection sensor detects a relative speed of an object located in the detectable area with respect to the vehicle, and cannot detect the relative speed if the object exists in the close range area. The control device calculates a change amount (time change rate) per unit time of the relative velocity, and when the target enters the short-distance area, calculates an estimated relative velocity based on an elapsed time from a final acquisition time, which is a time when the target relative velocity is finally acquired from the target detection sensor, to a current time, and a final acquisition relative velocity, which is a target relative velocity at the final acquisition time, and the time change rate.)

1. A vehicle control device, comprising:

a target detection sensor that is disposed at a predetermined portion of a vehicle, that is configured to be capable of detecting both a distance between a target and the vehicle and a relative speed of the target with respect to the vehicle when the target is located in a detectable region that is a portion of a predetermined region in a periphery of the vehicle and is a region that is greater than or equal to a predetermined minimum detection distance from the predetermined portion and less than a predetermined maximum detection distance, and that is a region where the distance from the predetermined portion is less than the minimum detection distance, and that is configured to be at least unable to detect the relative speed of the target with respect to the vehicle when the target is located in a short-distance region that is a region where the distance from the predetermined portion is less than the minimum detection distance; and

A control device that controls operation of an actuator mounted on the vehicle,

the control device is configured to:

acquiring the distance and the relative speed of an object located within the detectable area from the object detection sensor every time a predetermined time elapses,

calculating a time rate of change corresponding to an amount of change per unit time of the target relative velocity based on the acquired history of the relative velocity,

when an object located within the detectable area enters the short-distance area, calculating a relative speed of the object entering the short-distance area with respect to the current time of the vehicle as an estimated relative speed based on an elapsed time from a final acquisition time at which the relative speed of the object detected by the object detection sensor was last acquired from the object detection sensor to the current time, a final acquisition relative speed which is the relative speed of the object acquired from the object detection sensor at the final acquisition time, and the time change rate,

Controlling operation of the actuator based on the estimated relative velocity.

2. The vehicle control apparatus according to claim 1,

the control device is configured to:

when a collision condition that is established when the possibility of the target colliding with the vehicle is high is established, the estimated relative velocity is calculated as a collision-time estimated relative velocity on the basis of the time change rate, the final acquisition relative velocity, and a time from the final acquisition time to a collision time that is a time at which the collision condition is established,

whether to operate the actuator is determined based on the estimated relative speed at the time of collision.

3. The vehicle control apparatus according to claim 2,

the control device is configured to:

when it is determined that the collision condition is satisfied, the estimated collision-time relative velocity is calculated based on the time change rate, the final acquisition relative velocity, a time from the final acquisition time to a collision time that is a time at which the collision condition is satisfied, and a delay time required to acquire the latest value of the distance and the latest value of the relative velocity from the target detection sensor.

4. The vehicle control apparatus according to claim 2 or 3,

the vehicle control device further includes an impact detection sensor for detecting an impact index value representing an impact force applied to the vehicle,

the control device is configured to:

when the impact index value is equal to or greater than a first threshold value, it is determined that the collision condition is established.

5. The vehicle control apparatus according to claim 4,

the control device is configured to:

and an actuator that actuates an inflator for activating an airbag mounted on the vehicle, when the estimated relative velocity at the time of collision is greater than a predetermined threshold velocity and the impact index value is equal to or greater than a second threshold value that is greater than the first threshold value after the time of collision.

Technical Field

The present invention relates to a vehicle control device that estimates a relative speed of a target with respect to a vehicle when the distance between the target and the vehicle is less than a predetermined distance, and controls the operation of an actuator mounted on the vehicle based on the estimated relative speed.

Background

Conventionally known radar apparatuses (radar sensors) cannot detect a target when the target enters a short-distance area whose distance to the target is shorter than a predetermined minimum detection distance. Therefore, as one of vehicle control apparatuses using a radar apparatus (hereinafter referred to as "first conventional apparatus"), the position of such a target is estimated by extrapolation processing, and whether or not the target is present is determined based on the estimation result (see, for example, japanese patent application laid-open No. 2010-71805).

As another vehicle control device using a radar device (hereinafter referred to as "second conventional device"), the current target position is estimated based on "the position of the target relative to the vehicle and the relative speed of the target relative to the vehicle" detected last time by the radar device. Then, the second conventional apparatus converts the previous relative velocity into the current relative velocity in the coordinate system, and uses the converted relative velocity (converted relative velocity) as the current relative velocity (refer to japanese patent application laid-open No. 2019 and 2689).

However, when the target is located in the short distance region, the vehicle is highly likely to decelerate in order to avoid collision with the target, and therefore the target is less likely to maintain the relative speed. Therefore, the "second conventional apparatus that uses the converted relative velocity as the relative velocity of this time" cannot accurately estimate the relative velocity of the target located in the short distance region, and therefore there is a high possibility that the actuator cannot be appropriately controlled.

Disclosure of Invention

The present invention has been made to solve the above problems. That is, one object of the present invention is to provide a vehicle control device capable of estimating the relative speed of a target existing in a short distance region more accurately.

A vehicle control device (hereinafter, also referred to as "present invention device") according to the present invention includes:

an object detection sensor (12), the object detection sensor (12) being disposed at a predetermined portion of a vehicle, and is configured to be able to detect both a distance (L) between the target and the vehicle and a relative speed (Vr) of the target with respect to the vehicle when the target is located in the Detectable Area (DA), and in the case where an object exists in a near area (NDA), at least a relative speed of the object with respect to the vehicle cannot be detected, the Detectable Area (DA) is a part of a predetermined area of the periphery of the vehicle, and is an area which is more than a predetermined minimum detection distance (Lmin) and less than a predetermined maximum detection distance (Lmax) from the predetermined portion, the predetermined maximum detection distance (Lmax) is longer than the minimum detection distance, and the short-distance area (NDA) is an area having a distance from the predetermined portion smaller than the minimum detection distance; and

and a control device (10), wherein the control device (10) controls the operation of actuators (42 a-42 f, 52 a-52 d, 60 a-60 d) mounted on the vehicle.

Further, the control device is configured to:

acquiring the distance and the relative speed of an object located within the detectable area from the object detection sensor every time a predetermined time elapses (step 405),

Calculating a time rate of change (slope a) corresponding to an amount of change per unit time of the target relative velocity based on the acquired history of the relative velocity (step 620),

when an object located in the detectable area enters the short-distance area (yes at step 615), a relative speed of the object entering the short-distance area with respect to the current time of the vehicle is calculated and set as an estimated relative speed (step 630) based on an elapsed time from a final acquisition time (t _ last) at which the relative speed of the object detected by the object detection sensor was last acquired from the object detection sensor to the current time, a final acquisition relative speed (Vr _ last) at which the relative speed of the object acquired from the object detection sensor at the final acquisition time is acquired from the object detection sensor,

the operation of the actuator is controlled based on the estimated relative velocity (steps 650, 730).

In this way, the relative velocity of the target existing in the short-distance area is calculated based on the time rate of change of the relative velocity based on the history of the relative velocity while the target is present in the detectable area, and therefore, the estimated relative velocity of the target existing in the short-distance area can be accurately calculated. Therefore, the actuator can be appropriately controlled based on the estimated relative velocity.

In one aspect of the present invention, the substrate is,

the control device is configured to:

when a collision condition that is established when the possibility of the target colliding with the vehicle is high is established (YES at step 715), the estimated relative velocity is calculated as a collision-time estimated relative velocity on the basis of the time change rate, the final obtained relative velocity, and a time from the final obtained time to a collision time that is a time at which the collision condition is established (step 720),

whether to operate the actuator is decided based on the estimated relative speed at the time of collision (step 725).

Since there is a high possibility that the target exists in the close range at the time of collision, the target detection sensor cannot detect the relative speed of the target. According to the above aspect, the estimated collision relative velocity of the target at the time of collision is calculated based on the time change rate, the final acquisition relative velocity, and the "time from the final acquisition time to the time of collision", and therefore, the estimated collision relative velocity can be calculated more accurately.

Furthermore, in the above-described aspect,

the control device is configured to:

when it is determined that the collision condition is satisfied (yes at step 715), the estimated collision time relative velocity is calculated based on the time change rate, the final acquisition relative velocity, a time from the final acquisition time to a collision time that is a time at which the collision condition is satisfied, and a delay time (T3) required for the latest value of the distance and the latest value of the relative velocity to be acquired from the target detection sensor (step 720).

Accordingly, the estimated relative collision velocity is calculated in consideration of the delay time, and therefore, the estimated collision relative velocity can be calculated more accurately.

Furthermore, in the above-described aspect,

the vehicle control device is further provided with impact detection sensors (16, 18), wherein the impact detection sensors (16, 18) are used for detecting impact index values (Gx, P) representing impact force acting on the vehicle,

the control device is configured to: if the impact index value is equal to or greater than the first threshold value (yes at step 715), it is determined that the collision condition is satisfied.

This makes it possible to more accurately determine whether or not the collision condition is satisfied.

Furthermore, in the above-described aspect,

the control device is configured to:

when the estimated relative velocity at the time of collision is greater than a predetermined threshold velocity and the impact index value is equal to or greater than a second threshold value that is greater than the first threshold value after the time of collision (yes at step 725), an inflator for activating an airbag mounted on the vehicle is activated as the actuator (step 730).

Thus, the "inflator for activating the airbag" is activated when the estimated relative velocity is greater than the threshold velocity and the impact index value becomes equal to or greater than the second threshold value that is greater than the first threshold value at the time of collision after the collision time, and therefore, the airbag can be appropriately activated even if the target detection sensor fails due to the collision of the target with the vehicle.

In the above description, in order to facilitate understanding of the invention, the names and/or reference numerals used in the embodiments are given in parentheses for the configuration of the invention corresponding to the embodiments described later. However, the components of the present invention are not limited to the embodiments defined by the aforementioned names and/or reference numerals. Other objects, other features and attendant advantages of the present invention will be readily understood from the following description of the embodiments of the present invention with reference to the accompanying drawings.

Drawings

Features, advantages and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, wherein like reference numerals denote like parts, and wherein:

fig. 1 is a schematic system configuration diagram of a vehicle control device (present control device) according to an embodiment of the present invention.

Fig. 2 is a plan view of the vehicle for explaining the detection range of the millimeter wave radar device shown in fig. 1.

Fig. 3 is an explanatory diagram schematically illustrating the processing of the present control device.

Fig. 4 is a flowchart showing a routine executed by the CPU of the collision control ecu (ccucu) shown in fig. 1.

Fig. 5 is a flowchart showing a subroutine executed by the CPU of the CCECU shown in fig. 1 in the routine shown in fig. 4.

Fig. 6 is a flowchart showing another subroutine executed by the CPU of the CCECU shown in fig. 1 in the routine shown in fig. 4.

Fig. 7 is a flowchart showing another routine executed by the CPU of the CCECU shown in fig. 1.

Detailed Description

A vehicle control device according to an embodiment of the present invention (hereinafter referred to as the present control device) is applied to a vehicle VA (see fig. 2). The present control device is incorporated in a collision prevention safety device mounted on a vehicle VA. The collision-prevention safety device is provided with a collision control ECU (hereinafter referred to as "CCECU") 10, an engine ECU20, and a brake ECU 30. These ECUs are connected to each other so as to be able to exchange data (able to communicate) via a CAN (Controller Area Network) not shown.

The ECU is an electronic control unit for short, and is an electronic control circuit having a microcomputer as a main structural component, the microcomputer including a CPU, a ROM, a RAM, an interface, and the like. The CPU realizes various functions by executing instructions (routines) stored in a memory (ROM). These ECUs or several of them may also be integrated into one ECU.

The vehicle VA includes a millimeter wave radar device 12, a camera device 14, a floor sensor 16, a pressure sensor 18, an accelerator pedal operation amount sensor 22, an accelerator pedal 22a, an engine sensor 24, an engine actuator 26, a drive device (internal combustion engine) 28, a brake pedal operation amount sensor 34, a brake pedal 34a, a brake transmission device 36, a plurality of airbag actuators 40a to 40f, a plurality of airbags 42a to 42f, a plurality of seatbelt actuators 50a to 50d, a plurality of seatbelts 52a to 52d, and pop-up hood lifters 60a to 60 d.

The millimeter wave radar device 12, the camera device 14, the floor sensor 16, and the pressure sensor 18 are connected to the CCECU 10.

The millimeter wave radar device 12 is a well-known target detection sensor that detects a target by transmitting millimeter waves to the front of the vehicle VA and receiving millimeter waves reflected by the target (reflected waves). The millimeter wave radar device calculates a distance L to the target (target distance), a relative speed Vr of the target with respect to the vehicle VA (target relative speed), and an azimuth of the target based on the received reflected waves. The millimeter wave radar device 12 employs an FM-CW system. Details of such a millimeter wave radar device 12 are described in japanese patent laid-open No. 2017-9526.

As shown in fig. 2, the millimeter wave radar device 12 is disposed at the front end portion of the vehicle VA and at the center portion in the vehicle width direction (front end center portion). The millimeter wave radar device 12 transmits the millimeter waves propagating to the region from the front end center portion to the maximum detection distance Lmax at a predetermined angle θ d in the left and right directions with respect to the "center axis C1 extending from the front end center portion in the straight ahead direction of the vehicle VA". Therefore, the millimeter wave radar device 12 can calculate the distance L, the relative speed Vr, and the azimuth of the target existing in the above-described region. However, the millimeter wave radar device 12 cannot detect a target (that is, the distance L, the relative speed Vr, and the azimuth at which the target cannot be detected) NDA existing in a region (hereinafter, also referred to as a "short-distance region" or a "non-detection region") NDA smaller than the minimum detection distance Lmin from the center of the distal end. Therefore, the millimeter wave radar device 12 detects the distance L and the relative speed Vr of the target existing in the detectable region DA having the minimum detection distance Lmin or more and less than the maximum detection distance Lmax from the center portion of the front end, and transmits the distance L, the relative speed Vr, and the heading to the CCECU10 as radar target information every time a predetermined time elapses.

The camera device 14 is disposed at a central upper portion of a front window in a vehicle interior of the vehicle VA, and acquires an image (hereinafter, also referred to as a "front image") obtained by imaging a front region of the vehicle VA. The camera device 14 obtains "the distance to the target, the direction of the target, the position of the lane line on the road with respect to the vehicle VA", and the like "from the front image. Each time a predetermined time elapses, the camera apparatus 14 sends them as camera target information to the CCECU 10.

The CCECU10 obtains (determines) final target information by correcting the radar target information based on the camera target information.

The floor sensor 16 is fixed to a floor (i.e., a vehicle body floor structural member at a vehicle body center portion) constituting a cabin of the vehicle VA. The floor sensor 16 detects acceleration acting in the vehicle longitudinal direction of itself (hereinafter referred to as "floor acceleration Gx"), and transmits a detection signal indicating the floor acceleration Gx to the CCECU 10. The floor acceleration Gx is set to represent the acceleration (deceleration) of the rear of the vehicle VA as a positive value.

The pressure sensor 18 detects a pressure P inside a chamber (not shown) in a front bumper FB (see fig. 2) of the vehicle VA, and sends a detection signal indicating the pressure P to the ccucu 10.

The engine ECU20 is connected to the accelerator pedal operation amount sensor 22 and the engine sensor 24, and receives detection signals of these sensors.

The accelerator pedal operation amount sensor 22 sends a detection signal indicating an operation amount of an accelerator pedal 22a of the vehicle VA (accelerator pedal operation amount) to the engine ECU 20. The engine sensor 24 is a sensor that detects an operation state quantity of the internal combustion engine 28, and is, for example, a throttle opening sensor, an engine speed sensor, an intake air amount sensor, and the like.

The engine ECU20 is connected to the engine actuator 26 such as a "throttle actuator and a fuel injection valve". The engine ECU20 changes the torque generated by the internal combustion engine 28 by driving the engine actuator 26. The engine ECU20 determines a target throttle opening degree TAtgt that becomes larger as the accelerator pedal operation amount is larger, and controls the engine actuator 26 so that the actual throttle valve coincides with the target throttle opening degree TAtgt.

The brake ECU30 is connected to the brake pedal operation amount sensor 34 and the brake actuator 36 as a hydraulic control actuator. The brake pedal operation amount sensor 34 sends a detection signal indicating an operation amount of a brake pedal 34a (brake pedal operation amount) of the vehicle VA to the brake ECU 30.

The brake actuator 36 is disposed in a hydraulic circuit (not shown) between a "master cylinder (not shown) that pressurizes hydraulic oil by the stepping force of the brake pedal 34 a" and a "friction brake device (not shown) including a known wheel cylinder provided for each wheel". Also, the brake actuator 36 adjusts the hydraulic pressure supplied to the wheel cylinders.

The brake ECU30 determines an operation required deceleration Gbpd that increases as the amount of brake pedal operation increases, and drives the brake actuator 36 based on the operation required deceleration Gbpd to control the hydraulic pressure of the hydraulic oil supplied to the wheel cylinders. As a result, the actual deceleration (negative acceleration) of the vehicle VA is made to coincide with the operation required deceleration Gbpd by generating the adjusted braking force (friction braking force) at each wheel.

Each of the airbag actuators 40a to 40f is an actuator connected to the ccucu 10 and used to operate an inflator (not shown) for deploying the corresponding airbag 42a to 42 f. The airbags 42a to 42f of this example are provided at six locations, namely, the front of the driver's seat, the right side of the driver's seat, the front of the passenger's seat, the left side of the rear seat, and the right side of the rear seat.

Each of the belt actuators 50a to 50d is an actuator for winding the corresponding belt 52a to 52d in accordance with an instruction from the ccucu 10, thereby reducing the slack of the belts 52a to 52 d. The seat belts 52a to 52d are respectively provided in the driver seat, the front passenger seat, the left rear seat, and the right rear seat.

The pop-up hood lifters 60a to 60d are provided at positions corresponding to four corners of a hood, not shown, of the vehicle VA. In the case where the target collides with the vehicle VA, the pop-up hood lifters 60a to 60d operate in accordance with an instruction from the CCECU10 to lift the hood. This can ensure a space between the hood and the engine room, not shown, and thus can alleviate the impact on the target at the time of collision. The details of the pop-up hood lifters 60a to 60d are described in japanese patent application laid-open nos. 2018-187957, 2017-171030, 2017-109655, and the like.

(outline of work)

The outline of the operation of the present control device will be described with reference to fig. 3. The CCECU10 executes a pre-collision control process described later each time a predetermined first predetermined time Tac (see fig. 3) elapses, and executes a collision-time control process described later each time a predetermined second predetermined time Tbc (not shown) shorter than the first predetermined time Tac elapses.

< Pre-crash control processing >

In the pre-collision control process, the CCECU10 acquires radar target information and camera target information, and determines whether or not a pre-collision control condition is satisfied based on the acquired radar target information and camera target information. As described later, the pre-collision control condition is a condition that is established when there is a target with a high possibility of collision with the vehicle VA (hereinafter referred to as "collision target"). When it is determined that the pre-collision control condition is satisfied, the CCECU10 executes pre-collision control for avoiding the above-described collision by decelerating the vehicle VA.

< control processing at collision >

The CCECU10 acquires the floor acceleration Gx, and determines whether or not the "collision condition in which the floor acceleration Gx is equal to or greater than the first threshold acceleration Gx1 th" is satisfied. The CCECU10 determines whether or not the collision control condition is satisfied after the time when the collision condition is determined to be satisfied (hereinafter referred to as "collision time t _ co". refer to fig. 3). This collision control condition is satisfied when both of the condition a1 and the condition a2 described below are satisfied. The CCECU10 executes the collision-time control for deploying the airbags 42a to 42f when it is determined that the collision control condition is satisfied. Condition a 1: the relative speed of the collision target at the collision time t _ co (hereinafter referred to as the collision estimated relative speed) Vr _ co is equal to or higher than the collision threshold speed Vr2 th. Condition a 2: the floor acceleration Gx is equal to or greater than a second threshold acceleration Gx2th that is greater than the first threshold acceleration Gx1 th.

Further, since the collision target exists in the short-range area NDA at the collision time t _ co and immediately before the collision time t _ co, the millimeter wave radar device 12 cannot detect the collision target. In other words, the millimeter wave radar device 12 cannot acquire the relative speed Vr of the collision target. Therefore, the CCECU10 needs to estimate the estimated relative speed Vr _ co at the time of collision.

Therefore, in the pre-collision control process executed from "time ta at which the pre-collision control condition is established" to "time t _ NDA at which the collision target enters the short range NDA", the CCECU10 calculates the slope a of the relative speed Vr of the collision target with respect to time.

Then, in the pre-collision control process executed after time t _ NDA at which the collision target enters the short-distance area NDA, the CCECU10 estimates the relative speed Vr of the collision target (hereinafter referred to as "estimated relative speed Vrs") based on the above-described slope a and the following expression (1).

Vrs＝a*T1+b…(1)

"T1": the elapsed time from the final acquisition time t _ last (see fig. 3) at which the radar target information of the collision target is finally acquired in the pre-collision control process to the current time.

"b": the relative speed Vr at the time t _ last is finally acquired (hereinafter referred to as "finally acquired relative speed Vr _ last").

When the CCECU10 determines that the collision condition is satisfied at time t _ co, the CCECU10 estimates the relative speed Vr _ co at the time of collision in the collision control process according to the following expression (2).

Vr＿co＝a*(T2+T3)+Vrsp…(2)

"T2": a time from a time tb (near acquisition time) at which the pre-collision control process is executed immediately before the time t _ co (see fig. 3) to the time t _ co.

"T3": the delay time is set in advance in consideration of the time from when the millimeter wave radar device 12 transmits radar target information to the CCECU10 until the CCECU10 receives the radar target information (i.e., the time taken until the CCECU10 acquires the latest radar target information from the millimeter wave radar device 12).

"Vrsp": the estimated relative velocity Vrs estimated at the time tb is acquired.

As can be understood from the above, the CCECU10 estimates the estimated relative speed Vrs of the collision target existing in the short distance area NDA based on the "slope a based on the history of the relative speed Vr when the collision target exists in the detectable area DA". Therefore, the more accurate estimated relative speed Vrs can be estimated. Further, since the CCECU10 estimates the estimated relative speed Vr _ co at the time of collision based on the slope a, it is possible to estimate a more accurate estimated relative speed Vr _ co at the time of collision. Further, since the accurate estimated relative speed Vr _ co at the time of collision can be estimated, the CCECU10 can accurately determine whether or not the above condition a1 is satisfied. As a result, the CCECU10 can appropriately determine whether to execute the collision-time control.

(concrete work)

< Pre-crash control routine >

The CPU of the CCECU10 (hereinafter, in the case of being expressed as "CPU", the CPU of the CCECU10 is referred to unless otherwise specified) executes the pre-collision control routine shown in the flowchart in fig. 4 each time the first predetermined time Tac elapses.

Therefore, when the predetermined timing is reached, the CPU starts the process from step 400, sequentially executes steps 405 to 420, proceeds to step 495, and once ends the routine.

Step 405: the CPU acquires radar target information from the millimeter wave radar device 12. Step 410: the CPU acquires camera object information from the camera device 14. Step 415: the CPU executes a pre-collision control operation process for executing the pre-collision control when a pre-collision control condition (described later) is satisfied (see fig. 5). Step 420: when a collision target (a target that becomes a factor for executing the pre-collision control) enters the short-distance area NDA while the pre-collision control is being executed, the CPU executes a short-distance relative velocity estimation process (see fig. 6) for estimating a relative velocity vrs of the collision target.

< Pre-crash control operation routine >

The CPU executes the subroutine shown in the flowchart in fig. 5 when advancing to step 415. That is, the CPU starts the process from step 500 shown in fig. 5, and determines in step 505 whether or not the value of the pre-collision control flag Xpcs is "0".

The value of the pre-collision control flag Xpcs is set to "1" when the CPU starts the pre-collision control (refer to step 520), and is set to "0" when the CPU ends the pre-collision control (refer to step 535). In an initial routine executed when an ignition key switch, not shown, of the vehicle VA is changed from an off position to an on position, the CPU sets the value of the pre-collision control flag Xpcs to "0".

When the value of the pre-collision control flag Xpcs is "0", the CPU makes a yes determination at step 505, proceeds to step 510, and calculates a TTC (Time to collision, also referred to as "collision delay Time") indicating the Time taken until each target collides with the vehicle VA. More specifically, the CPU calculates the TTC by substituting the target distance L and the target relative velocity Vr into the following expression (3).

TTC＝L/Vr…(3)

Next, the CPU proceeds to step 515 to determine whether or not a pre-collision control condition is satisfied in which TTC is equal to or less than the threshold time Tsth. Further, in the case where there are a plurality of targets (i.e., in the case where a plurality of TTCs are calculated), the CPU determines whether or not the smallest TTC among them is below the threshold time Tsth.

If TTC is greater than threshold time Tsth (i.e., if the pre-collision control condition is not satisfied), the CPU makes a determination of no at step 515, proceeds to step 595, and once ends the present routine.

On the other hand, if TTC is equal to or less than threshold time Tsth (that is, if the pre-collision control condition is satisfied), the CPU makes a determination of yes at step 515, sequentially executes steps 520 and 525, proceeds to step 595, and once ends the present routine.

Step 520: the CPU sets the value of the pre-collision control flag Xpcs to "1". Step 525: the CPU executes pre-collision control described below.

Step 525 is described in more detail. The CPU sends a predetermined PCS requested deceleration gpc to the engine ECU20 and the brake ECU 30. When receiving the PCS required deceleration gpc, the engine ECU20 sets the target throttle opening degree TAtgt to "0" regardless of the accelerator pedal operation amount. The brake ECU30 controls the brake actuator 36 based on the deceleration, which is the larger of the operation requested deceleration Gbpd and the PCS requested deceleration gpc.

On the other hand, when the value of the pre-collision control flag Xpcs is "1" at the time point when the process proceeds to step 505, the CPU determines no in step 505, proceeds to step 530, and determines whether or not the PCS end condition is satisfied. This PCS end condition is satisfied when the value of collision flag Xco described later is "0" and TTC is equal to or greater than threshold time Teth. The threshold time Teth is set to a value greater than the threshold time Tsth.

The value of the collision flag Xco is set to "1" when the aforementioned collision condition is satisfied (see step 718 shown in fig. 7), and is set to "0" when a predetermined post-collision time has elapsed from the time when the collision condition is satisfied (see step 750 shown in fig. 7). Further, the CPU sets the value of the collision flag Xco to "0" in the above-described initial routine.

If the termination condition is not satisfied, the CPU determines no at step 530 and proceeds to step 525. On the other hand, when the termination condition is satisfied, the CPU determines yes in step 530, proceeds to step 535, sets both the value of the pre-collision control flag Xpcs and the value of the short-range area flag Xnda, which will be described later, to "0", and sets the values of the slope a, the intercept b, and the timer T1, which will be described later, to an invalid value "null". After that, the CPU proceeds to step 595 and temporarily ends the present routine.

< short-distance relative speed estimation routine >

The CPU executes the subroutine shown in the flowchart in fig. 6 when advancing to step 420. That is, the CPU starts the process from step 600 shown in fig. 6, and determines in step 605 whether or not the value of the pre-collision control flag Xpcs is "1". When the value of the pre-collision control flag Xpcs is "0", the CPU makes a determination of no in step 605, proceeds to step 695, and once ends the routine.

On the other hand, if the value of the pre-collision control flag Xpcs is "1", the CPU determines yes in step 605, proceeds to step 610, and determines whether or not the value of the short-distance area flag Xnda is "0".

The value of the short range flag Xnda is set to "1" when the pre-collision control is executed and it is determined that the collision target exists in the short range NDA (refer to step 625), and is set to "0" when the pre-collision control is ended (refer to step 535 shown in fig. 5). Then, the CPU sets the value of the short-distance area flag Xnda to "0" in the above-described initial routine.

If the value of the short-range area flag Xnda is "0", the CPU determines yes in step 610, proceeds to step 615, and determines whether or not a collision target exists in the short-range area NDA. More specifically, the CPU determines whether or not a short-distance non-detection condition described below is satisfied, and determines that the collision target exists in the short-distance area NDA if it is determined that the short-distance non-detection condition is satisfied.

The short-distance non-detection condition is satisfied in the following case. The millimeter wave radar device 12 cannot detect that a collision target exists in the vicinity of the position of the current time of the collision target estimated based on the history of the "position included in the radar target information" of the collision target obtained during the first period from the time when the pre-collision control condition is satisfied to the time when the present routine was executed last time (i.e., from the current time to the time before the first predetermined time Tac). The position of the collision target is "a relative position with respect to the vehicle VA" that is determined based on the radar target information alone or based on both the radar target information and the camera target information.

The short-distance non-detection condition may be satisfied in the following case. The same target as the target that becomes the target for which the pre-collision control condition is established is included in the front image, and radar target information about the same target as the target cannot be obtained.

When the short-distance non-detection condition is not satisfied, there is a high possibility that the collision target exists in the detectable area DA. Therefore, in this case, the CPU determines no in step 615, proceeds to step 620, and calculates (estimates) "the slope a of the relative speed of the collision target with respect to time" based on "the relative speeds Vr of the plurality of collision targets" obtained in the first period. The slope a is estimated by linearly approximating a point determined by the relative velocity Vr and the time at which the relative velocity Vr is obtained, for example, by using the least square method. Thereafter, the CPU proceeds to step 695 to end the routine temporarily.

On the other hand, when the short-distance non-detection condition is satisfied at the time when the CPU proceeds to step 615, the CPU determines that the collision target exists in the short-distance area NDA and determines yes in step 615. Then, the CPU sequentially executes the processing of steps 625 to 635, and proceeds to step 640.

Step 625: the CPU sets the value of the short-range region flag Xnda to "1", sets the intercept b to "the relative speed Vr _ last (the final acquired relative speed Vr _ last) of the collision target detected last", and sets the timer T1 to "0".

Step 630: the CPU adds the first predetermined time Tac to the timer T1.

Step 635: the CPU calculates (estimates) the estimated relative speed Vrs by applying the slope a, the value of the timer T1, and the intercept b to the expression (1). Then, the CPU stores the estimated relative speed Vrs in the RAM as the estimated relative speed Vrsp of the above expression (2).

Step 640: the CPU determines whether or not the value of the timer T1 is equal to or greater than a first threshold time T1 th.

When the value of the timer T1 is smaller than the predetermined first threshold time T1th, the CPU makes a determination of no at step 640, proceeds to step 695, and temporarily ends the present routine. The first threshold time T1th is set to a time sufficiently shorter than a time from a time when the collision target enters the short-range area NDA (a time when the short-range non-detection condition is satisfied) to a time when it is estimated that the collision target actually collides with the vehicle VA.

If the CPU executes the present routine next while such a state continues, the CPU makes a determination of yes at step 605, and makes a determination of no at step 610, and proceeds to step 630. By repeating such processing, the value of the timer T1 is gradually increased by the processing of step 630.

Therefore, when the CPU proceeds to step 640 after the value of the timer T1 becomes equal to or greater than the first threshold time T1th, the CPU determines yes at step 640, proceeds to step 645, and determines whether or not the estimated relative speed Vrs is equal to or greater than the winding threshold speed Vr1 th. When the estimated relative speed Vrs is lower than the winding threshold speed Vr1th, the CPU makes a determination of no at step 645, and proceeds to step 695 to end the routine once.

On the other hand, if the estimated relative speed Vrs is equal to or higher than the winding threshold speed Vr1th, the CPU determines yes at step 645, executes the webbing winding control at step 650, proceeds to step 695, and once ends the routine. More specifically describing the processing of step 650, the CPU transmits a winding signal to each of the belt actuators 50a to 50 d. Upon receiving the take-up signal, each of the belt actuators 50a to 50d takes up the corresponding belt 52a to 52d by a predetermined amount.

In this manner, when the collision target enters the short-range area NDA and the estimated relative speed Vrs is equal to or higher than the winding threshold speed Vr1th after a predetermined time (first threshold time T1th) has elapsed since the time of entry, it can be determined that the vehicle VA has a very high possibility of colliding with the collision target. Therefore, the CPU executes the above-described webbing take-up control in this case.

< control routine at collision >

The CPU executes a crash-time control routine shown in a flowchart in fig. 7 each time the second predetermined time Tbc elapses.

Therefore, when the predetermined timing is reached, the CPU starts the process from step 700 and proceeds to step 705, where the floor acceleration Gx is acquired from the floor sensor 16. Next, the CPU proceeds to step 710 to determine whether or not the value of the collision flag Xco is "0".

If no collision has occurred until the current time, the value of the collision flag Xco is "0". In this case, the CPU makes a "YES" determination at step 710, proceeds to step 715, and determines whether or not the collision condition (i.e., Gx ≧ Gx1th) is satisfied. If the collision condition is not satisfied, the CPU makes a determination of no at step 715, and proceeds to step 795 to end the routine once.

On the other hand, when the collision condition is satisfied, the CPU determines yes at step 715 and sequentially executes the processes at step 718 and step 720.

Step 718: the CPU sets the value of the collision flag Xco to "1", and sets the value of the timer Taft to "0". Step 720: the CPU calculates the estimated collision relative speed Vr _ co according to the above expression (2) (i.e., Vr _ co ═ a (T2+ T3) + Vrsp … (2)), and stores the estimated collision relative speed Vr _ co in the RAM.

The values on the right side of the above expression (2) are as follows.

Slope a: slope a calculated in step 620 of fig. 6

Time T2: the value of the execution timer represents the elapsed time from the processing time of step 635, which is executed immediately before the time of the processing of step 720, based on the time of the value of the execution timer. Further, the CPU increments the value of the execution timer each time an extremely short unit time elapses, and when the value of the execution timer reaches a threshold value indicating the first predetermined time Tac, starts the processing of the routine of the pre-collision control processing shown in fig. 4, and initializes the value of the execution timer.

Time T3: predetermined constant time (delay time)

Estimated relative velocity Vrsp: the estimated relative speed Vrs stored in the RAM at a time immediately before the time when the processing of step 720 is executed is stored in step 635 in fig. 6

Next, the CPU proceeds to step 725 to determine whether or not the collision control conditions (condition a1 and condition a2) are satisfied.

If the collision control condition is not satisfied, the CPU makes a determination of no at step 725, and proceeds to step 795 to end the routine once.

On the other hand, when the collision control condition is satisfied, the CPU determines yes at step 725, executes collision control at step 730, and proceeds to step 795 to end the routine once. More specifically describing the process of step 730, the CPU transmits an airbag deployment signal to each of the airbag actuators 40a to 40 f. The airbag actuators 40a to 40f deploy the corresponding airbags 42a to 42f by activating the corresponding inflators upon receiving the airbag deployment signal.

On the other hand, when the value of the collision flag Xco is "1" at the time when the CPU proceeds to step 710, the CPU makes a determination of no at step 710 and executes the processing of step 735 and step 740 described below.

Step 735: the CPU adds the second predetermined time Tbc to the value of the timer Taft. As a result, the value of the timer Taft becomes a value indicating the elapsed time from the time when the collision condition is established.

Step 740: the CPU determines whether or not the value of the timer Taft is equal to or less than the second threshold time T2 th. The second threshold time T2th is set to a value corresponding to the time from the time when the collision occurs to the time when the collision control is not necessary.

If the value of the timer Taft is equal to or less than the second threshold time T2th (i.e., if the predetermined post-collision time has not elapsed from the time when the collision condition is established), the CPU makes a yes determination at step 740, holds the estimated collision relative speed Vr _ co at step 745, and proceeds to step 725. In step 725, the CPU determines whether or not the condition a1 is satisfied using the estimated collision relative speed Vr _ co held in step 745. Since there is a possibility that the millimeter wave radar device 12 fails due to a shock when the collision condition is satisfied and transmits an abnormal value to the CCECU10, the CPU determines the condition a1 by using the estimated collision relative velocity Vr _ co at the timing when the collision condition is satisfied, without sequentially calculating the estimated collision relative velocity Vr _ co.

On the other hand, when the CPU proceeds to the time of step 740 and the value of the timer Taft is larger than the second threshold time T2th (that is, when a predetermined post-collision time has elapsed from the time when the collision condition is satisfied), the CPU determines no in step 740 and proceeds to step 750.

In step 750, the CPU erases the estimated relative speed Vr _ co at the time of collision from the RAM, sets the value of the collision flag Xco to "0", and sets the value of the timer Taft to "0".

As can be understood from the above, in the case where the collision target exists in the short distance area NDA, the CCECU10 estimates the estimated relative speed Vrs based on the slope a of the relative speed Vr when the collision target exists in the detectable area DA. This makes it possible to accurately estimate the relative speed of the collision target existing in the short-distance area NDA.

The present invention is not limited to the above-described embodiments, and various modifications of the present invention can be adopted. For example, in step 705 shown in fig. 7, the CPU may acquire the pressure P from the pressure sensor 18 instead of the floor acceleration Gx. In this case, in step 715, the CPU determines whether or not a collision condition in which the pressure P is equal to or greater than the first threshold pressure P1th is satisfied. Then, in step 725, the CPU determines whether or not the pressure P is equal to or higher than the second threshold pressure P2th, which is greater than the first threshold pressure P1th, in place of the condition a 2.

In step 730, the CPU may execute control for raising the hood by operating the pop-up hood elevators 60a to 60d as collision control. In this case, the CPU transmits an operation signal to each of the pop-up hood lifters 60a to 60 d. Each of the pop-up hood lifters 60a to 60d operates upon receiving the operation signal so as to lift the hood.

In step 720, the CPU may estimate the estimated relative speed Vr _ co at the time of collision according to the following expression (4).

Vr＿co＝a*(T1+T2+T3)+Vr＿last…(4)

In both the above expressions (2) and (4), the estimated collision speed Vr _ co is calculated based on the sum of the slope a, the final acquisition relative speed Vr _ last, the elapsed time from the final acquisition time T _ last to the collision time (T1+ T2), and the delay time T3.

The millimeter wave radar device 12 may be any remote sensing device (object detection sensor) that transmits a wireless medium instead of millimeter waves and can detect an object by receiving a reflected wireless medium.

The CPU can specify the distance L and the direction of the target existing in the short-distance area NDA based on the camera target information, but cannot specify the relative speed Vr even based on the camera target information. Therefore, the short-range region NDA can be expressed as a region where at least the relative speed Vr among the distance L, the relative speed Vr, and the azimuth of the target can no longer be detected.

The floor sensor 16 and the pressure sensor 18 are sensors that detect impact index values (floor acceleration Gx and pressure P) indicating an impact force acting on the vehicle. Instead of the floor sensor 16 and the pressure sensor 18, another sensor capable of detecting the impact index value may be used.