JP5724905B2 - Collision damage reduction system, device control device, collision damage reduction method - Google Patents

Description

  The present invention relates to a collision damage reduction system that performs damage reduction control in accordance with TTC with an object.

  There is known a pre-crash safety technique (hereinafter referred to as PCS) in which an obstacle is monitored by a radar or a camera, and when it is determined that there is a possibility of a collision, a driver is warned or a brake ACT is operated to brake the vehicle. For example, TTC (Time To Collision) is used as an index for determining the possibility of collision with an object (see, for example, Patent Document 1). Patent Document 1 discloses a collision damage alleviating device that activates an automatic brake when a TTC calculation unit calculates a TTC and the TTC is equal to or less than a threshold value.

  As described above, in the PCS, a process of collision judgment with an object is required before warning or automatic braking. However, since the calculation cycle of an ECU (Electronic Control Unit) that performs collision judgment is relatively long, the automatic braking operation is performed. It is known that the timing may be delayed.

JP 2011-105250 A JP 2007-176483 A

  In contrast to the case where the automatic braking operation timing may be delayed, it is conceivable that the ECU that performs automatic braking acts as a proxy for the collision determination. Since the ECU that performs automatic braking has a short operation cycle, it is possible to determine the collision several times before the ECU that performs the collision determination updates the information.

  FIG. 11 is an example of a diagram illustrating an example of a system configuration when the ECU that performs automatic braking performs collision determination. In the figure, the brake ECU is an ECU that performs automatic braking. The collision determination ECU determines the possibility of a collision at a cycle of 30 milliseconds, and determines whether the brake ECU automatically brakes at a cycle of 5 milliseconds.

  For example, it is assumed that the brake ECU sets the operation TTC to 0.60 milliseconds. When the collision determination ECU transmits TTC = 0.61 milliseconds, conventionally, the brake ECU can automatically brake TTC = 0.58 milliseconds after 30 milliseconds. On the other hand, when the brake ECU interpolates TTC at a cycle of 5 milliseconds, the brake ECU can perform automatic braking at TTC = 0.60 milliseconds.

  By the way, the possibility of a collision with the preceding vehicle increases or decreases not only by the TTC but also by the lateral position of the preceding vehicle with respect to the host vehicle. Therefore, it is preferable that the ECU that performs automatic braking considers the lateral position of the preceding vehicle in addition to the process of interpolating TTC (see, for example, Patent Document 2). Patent Document 2 discloses a preceding vehicle selection device that detects the position of the preceding vehicle in the lateral direction after a predetermined time has elapsed using the lateral movement speed of the preceding vehicle.

  However, since the preceding vehicle selection device disclosed in Patent Document 2 predicts the lateral position of the preceding vehicle only from the speed in the lateral direction of the preceding vehicle, there is a problem that the accuracy of the predicted lateral position is low. For example, a driver of a preceding vehicle may notice a rear vehicle (own vehicle) by looking at a rearview mirror, a rearview mirror, or the like, or a rear radar approaching the preceding vehicle from behind may be mounted. In this case, it is considered that the driver of the preceding vehicle steers to avoid approaching the rear vehicle, and there is a possibility that there is no possibility of colliding with the preceding vehicle when a predetermined time elapses.

  For this reason, it is conceivable that the driver of the preceding vehicle is estimated to avoid with the maximum steering amount, and the lateral position of the preceding vehicle after a predetermined time has elapsed is predicted. However, if it is always estimated that the driver of the preceding vehicle avoids with the maximum steering amount, it is difficult to determine that a collision occurs, so that the effect of interpolating TTC is reduced.

  FIG. 12A is an example for explaining that the effect of interpolating TTC is reduced. When considering the movable range of the preceding vehicle after the lapse of a predetermined time, the range becomes wide if the moving range at a physical limit such as the maximum steering amount is simply considered. As shown in FIG. 12A, the range of motion when the constraint is not considered for the preceding vehicle (the range of movement at the physical limit) is wider than the range of motion when the constraint is considered.

  If the range of movement of the preceding vehicle is predicted widely, it is necessary to tighten the reference value (lateral determination threshold value) for collision determination in order to suppress unnecessary warnings. FIG. 12B is an example of a diagram for explaining the relationship between the presence / absence of restriction consideration and the severity of the regulation value. As shown in FIG. 12A, since the range of motion that does not consider the constraints is wider than the case where it is considered, the amount of lateral movement in the information update interval (for example, 30 milliseconds) becomes large. For this reason, it becomes necessary to make the reference value of the collision determination small (to make it difficult to determine that there is a collision) to the extent that the amount of possible lateral movement increases. If the reference value for collision determination is reduced, the effect of suppressing the operation delay by interpolating TTC described with reference to FIG. 11 is reduced.

  In view of the above problems, an object of the present invention is to provide a collision damage reduction system that appropriately performs a collision determination with respect to the lateral position of an object when determining the execution timing of damage reduction control by interpolating TTC.

  The present invention relates to an object detection device that detects an object, an arrival time calculation device that calculates an arrival time to the object, and an apparatus that controls the collision damage reduction device by evaluating the arrival time. A collision damage reduction system having a control device, wherein the device control device uses a reference value for determining whether or not a lateral position of the object collides with the host vehicle as the arrival time equal to or less than a threshold value. In this case, the lateral position reference value adjusting means for making the arrival time smaller than the case where the arrival time is larger than a threshold value, and the arrival time when the lateral position of the object is smaller than the reference value adjusted by the lateral position reference value adjusting means. The elapsed time counting means for counting the elapsed time from the time acquired from the arrival time calculating device, and the control of the avoidance device is started when the time obtained by subtracting the elapsed time from the arrival time is equal to or less than a threshold value. And avoid the device control means, characterized in that it has.

  When determining the execution timing of damage reduction control by interpolating TTC, it is possible to provide a collision damage reduction system that appropriately performs a collision determination with respect to the lateral position of an object.

It is an example of the figure explaining determination of the operation timing of the actuator by a collision damage reduction system. It is an example of the schematic block diagram of a damage reduction system. It is an example of the figure explaining distance L detected by a millimeter wave radar sensor, relative velocity v, and lateral position x. It is an example of the figure explaining the distance L detected by a stereo camera, the relative speed v, and a horizontal position. It is an example of a functional block diagram of a brake ECU. It is an example of the figure which illustrates alarm MAP and braking MAP typically. It is an example of the figure explaining a horizontal position etc. It is a flowchart figure which shows an example of the operation procedure of collision judgment ECU and brake ECU. It is an example of the functional block diagram of collision judgment ECU and brake ECU. (Example 2) which is a flowchart figure which shows an example of the operation procedure of collision judgment ECU and brake ECU. It is an example of the figure explaining the example of a system configuration at the time of ECU which performs automatic braking acting as a collision judgment. It is an example of the figure explaining prediction of a horizontal position etc.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

FIG. 1 is an example of a diagram for explaining the determination of the operation timing of the actuator by the collision damage reduction system of the present embodiment.
(1) The brake ECU compares TTC (Time To Collision) with a threshold value (actuation TTC) and switches the MAP to be referred to (alarm MAP and braking MAP).

  Any MAP is a MAP for determining the lateral G upper limit value corresponding to the speed of the object. The warning MAP is a MAP that is referred to by the host vehicle when it is included in a time zone in which the TTC may warn, and the braking MAP is a host vehicle that is included in a time zone in which the TTC may be braked. MAP referred to in As shown in the figure, the lateral G upper limit value determined by the braking MAP is larger than the lateral G upper limit value determined by the warning MAP even when the speed of the preceding vehicle is the same. These MAPs enable the brake ECU to appropriately predict the lateral position of the object in consideration of the steering amount of the driver of the object (preceding vehicle) depending on the situation.

Further, since the lateral G upper limit value increases as the vehicle speed of the preceding vehicle increases, the lateral position variation amount of the object can be considered according to the vehicle speed of the preceding vehicle (object).
(2) Next, the brake ECU determines the lateral position reference value based on the lateral G upper limit value determined from the MAP. The lateral position reference value is a threshold value for determining whether the lateral position of the preceding vehicle is at a position where it collides with the host vehicle. The lateral position reference value decreases as the lateral G upper limit value increases. This corresponds to making the operation determination stricter. Therefore, when the TTC is small enough to perform braking in the information update interval of the collision determination ECU, it means that it is difficult to determine that braking is performed. That is, since it is considered that the driver of the preceding vehicle steers largely to avoid a collision, unnecessary operation can be suppressed by making the lateral position reference value strict accordingly. On the other hand, if the TTC is small enough not to brake, but to warn, it is considered that the driver does not steer so much in order to avoid a collision.
(3) When the lateral position of the preceding vehicle is smaller than the lateral position reference value, the brake ECU determines that an alarm or braking is performed.

  Therefore, when the brake ECU interpolates the TTC, the lateral position reference value is determined in consideration of the steering amount of the driver of the preceding vehicle in accordance with the TTC, so that the severity of the lateral position reference value is sufficiently and sufficiently suppressed. Can do. Further, even when the lateral position reference value is tightened, when it is necessary to alarm or brake, since the operation delay is suppressed by interpolating the TTC, the effect can be sufficiently exhibited.

[Configuration example]
FIG. 2 shows an example of a schematic configuration diagram of the damage reduction system 100. The damage reduction system 100 includes a sensor unit 10, a collision determination ECU 11, a brake ECU 12, a brake ACT 13, and a meter buzzer 14, and the sensor unit 10, the collision determination ECU 11 and the brake ECU 12 are connected via an in-vehicle LAN such as CAN. Yes. The brake ECU 12 and the brake ACT 13 are connected by a dedicated line, and the brake ECU 12 and the meter buzzer 14 are connected by an in-vehicle LAN or a dedicated line.

(Sensor part)
Although the millimeter wave radar sensor 15 and the stereo camera 16 are illustrated as the sensor unit 10, it is sufficient that at least one of them is provided. The millimeter wave radar sensor 15 is disposed at the center of the front of the vehicle such as the front grille of the vehicle, and emits a millimeter wave at a predetermined angle (for example, 10 degrees left and right with the front as the center). Receives millimeter waves reflected by objects in range. The millimeter wave radar sensor 15 is, for example, an FMCW (Frequency Modulated Continuous Wave) radar.

  FIG. 3 is an example of a diagram for explaining the distance L, the relative velocity v, and the lateral position x detected by the millimeter wave radar sensor 15. The millimeter wave radar sensor 15 has one or more transmitting antennas and N receiving antennas. The millimeter wave radar sensor 15 switches the reception antenna in a time division manner with a switch while transmitting a millimeter wave that rises at a constant speed and descends at a constant speed from the transmission antenna. The millimeter wave radar sensor 15 generates a beat signal of the transmission signal and the reception signal for each reception antenna by mixing the transmission signal and the reception signal with a mixer. The phase difference between the transmission signal and the reception signal is proportional to the distance from the object, and the frequency of the beat signal is shifted by the relative speed. Therefore, the beat signal is subjected to FFT analysis, for example, and the distance and relative speed with respect to the object can be obtained from the beat frequency when the transmission frequency is increased and the beat frequency when the transmission frequency is decreased.

  In addition, the millimeter wave reflected from the object in front of the host vehicle has the same frequency phase of the beat signal without depending on the position of the receiving antenna. On the other hand, the millimeter wave reflected at an angle with respect to the front direction of the host vehicle has a phase difference based on the path difference between the transmitting antenna and the receiving antenna. By performing MUSIC analysis or the like on the phase / amplitude of each frequency obtained by the FFT analysis, the lateral position x or orientation θ of the object with respect to the vehicle position can be obtained. The lateral position corresponds to the center position in the width direction of the object with reference to the center position in the lateral direction of the host vehicle. Thus, the azimuth θ up to the lateral position x or the center position (lateral position x) of the preceding vehicle at the distance L and the relative speed v is obtained.

  The millimeter wave radar sensor 15 transmits the distances, relative speeds, and lateral positions of all detected objects to the collision determination ECU 11.

  Subsequently, detection of an object by the stereo camera 16 will be described. For example, the stereo camera 16 is arranged on the rearview mirror with the optical axis facing the front of the vehicle. The stereo camera 16 has two CCD cameras or two CMOS cameras that are spaced apart from each other by a predetermined interval. The stereo camera 16 performs preprocessing for removing lens distortion, optical axis deviation, focal length deviation, imaging element distortion, and the like on the frames imaged by each camera using calibration data prepared in advance. As a result, the frames of the two cameras have only a difference corresponding to parallax.

  FIG. 4 is an example for explaining the distance L, the relative speed v, and the lateral position detected by the stereo camera 16. The stereo camera 16 calculates the parallax generated in the pixels where the same object is photographed from the correlation between the two image data. Specifically, the image data of the left camera is fixed, and the target pixel is sequentially selected. Then, for each pixel block of a predetermined size centered on the pixel of interest, a pixel block at a corresponding position in the image data of the right camera is extracted, and the most correlated shift amount is determined. The stereo camera 16 calculates the difference (or sum of squares) of the luminance of each pixel of the two pixel blocks. This is repeated while shifting the pixel block of the right camera one pixel at a time with the predetermined maximum shift amount as the upper limit. Therefore, a difference in luminance between the pixels of the two pixel blocks is obtained for each position shifted vertically and horizontally.

  Then, the stereo camera 16 obtains the shift position at which the sum (or sum of squares) of the luminance differences of the respective pixels is the smallest as the shift amount of the pixel of interest. By performing this operation for all pixels, a shift amount can be obtained for each pixel.

If the number of shifted pixels is n, the focal length of the lens is f, the distance between the optical axes (between two cameras) is m, and the pixel pitch is d, the distance L to the imaging object is
L = (f × m) / (n × d)
It is obtained from the relational expression. Since the distance L is obtained for each pixel of interest (or for each pixel block), the distance L to a wide range of objects photographed in the frame is obtained as shown in FIG.

  The stereo camera 16 groups the objects with respect to the distance information of the image. First, an area where a road surface is photographed exists in the image data. When the road surface is photographed, the distance to the road surface (that is, parallax) is determined by the pixel position. Since the distance to the object is always shorter than the distance to the road surface, it is determined that a pixel that has a parallax equivalent to the upper limit of the parallax determined in advance by the pixel position is the road surface, and is subject to grouping Excluded from.

  In addition, distance information (a three-dimensional database of assumed three-dimensional objects) when a two-wheeled vehicle, a preceding vehicle, a pedestrian, and the like are photographed can be prepared in advance. For example, if approximately the same distance information is obtained in the shape viewed from the rear of the preceding vehicle, it can be determined that the vehicle is a preceding vehicle (in the figure, approximately L distance information is obtained for the preceding vehicle). In addition, these can be identified by preparing in advance distance information when guardrails, curbs, utility poles, and traffic signs that exist along the road are photographed. The stereo camera 16 identifies the object by comparing the distance information with the distance information of each object prepared in advance.

The horizontal position x of the object can be obtained from the number of pixels from the horizontal center position to the object and the focal length f in the image data.
x = (distance L to the object × number of pixels from the center position to the object × pixel pitch) / focal length f
As shown in FIG. 4B, each object is plotted in a coordinate system in which the width direction is the x axis and the front-rear direction is the y axis with the host vehicle as the origin. The relative distance L with respect to the preceding vehicle is L = √ (x ² + y ² ). In this way, the coordinates of each object with the vehicle position at the center are obtained in a certain frame. Since each camera captures a predetermined number (30 to 60) frames per second, the relative velocity v can be obtained by determining the change in coordinates of each object for each frame.

  The width of the object is the width of the grouped object itself. Since the x-coordinate and y-coordinate of the left and right ends of the object are also clear, the center position (lateral position) or azimuth θ in the width direction of the object is also obtained.

  The stereo camera 16 transmits the distances, relative speeds, and lateral positions of all the objects within a predetermined distance among the grouped objects to the collision determination ECU 11.

  In this way, the millimeter wave radar sensor 15 and the stereo camera 16 can obtain equivalent information. However, the millimeter wave radar sensor 15 has high accuracy in distance and relative velocity, and the stereo camera 16 has low accuracy in distance and relative velocity and high accuracy in azimuth. Therefore, in the actual vehicle, the vehicle control is performed mainly using high-precision information of each sensor, and the reliability of the information is determined by comparing two pieces of information. The sensor unit 10 transmits the distance to the object, the relative speed, and the lateral position to the collision determination ECU 11 at intervals of 50 milliseconds, for example, and the stereo camera 16 at intervals of 100 milliseconds.

[Collision judgment ECU]
Returning to FIG. 2, the collision determination ECU 11 calculates TTC and determines the possibility of collision based on the distance, relative speed, and lateral position. For example, TTC is calculated as follows.
TTC = distance / relative speed For each detected object, the collision determination ECU 11 detects the object having the highest possibility of collision from the TTC and the lateral position (in the objects whose lateral position is closer to the vehicle than the predetermined value). The object having the smallest TTC is specified, and the collision determination target information of the object is sent to the brake ECU 12.
The collision determination target information = TTC, the lateral position, the speed of the object, and the object lateral speed TTC and the lateral position use data transmitted from the sensor unit 10. The speed of the object (the speed of the object relative to the road surface) is obtained from the relative speed and the vehicle speed of the host vehicle (speed relative to the road surface). In both cases, the traveling direction of the host vehicle is positive.
The speed of the object = the vehicle speed of the host vehicle-the relative speed The object lateral speed is obtained by differentiating the lateral position received from the sensor unit 10 with respect to time.

  The collision determination ECU 11 transmits to the brake ECU 12 the collision determination target information of the object determined to have the highest possibility of collision from the TTC and the lateral position.

[Brake ECU]
The brake ECU 12 is connected to the brake ACT 13 and the meter buzzer 14. The brake ECU 12 transmits an actuator operation request to at least one of the brake ACT 13 or the meter / buzzer 14 in accordance with TTC.

  The brake ACT 13 includes a pressure reducing control valve (normally closed valve), a holding control valve (normally opened valve), and a hydraulic pressure for controlling the wheel cylinder pressure for each wheel in a hydraulic path communicating with the wheel cylinder of each wheel. A pump and a pump motor for generating are arranged. When automatic braking is not performed, the brake ECU 12 keeps the pressure reduction control valve closed and the holding control valve open. When the driver operates the brake pedal, the working fluid passes through the holding valve and is supplied to the wheel cylinder.

  When automatic braking is performed, the brake ECU 12 operates the pump motor while the pressure-reducing control valve and the holding control valve remain normal. As a result, the working fluid passes through the holding valve and is supplied to the wheel cylinder.

  When maintaining the current braking force, the brake ECU 12 closes the holding control valve while closing the pressure-reducing control valve. In this way, the braking force is maintained because the working fluid of the wheel cylinder does not increase or decrease. When reducing the current braking force, the brake ECU 12 opens the pressure reducing control valve while closing the holding control valve. By doing so, a new working fluid does not flow into the wheel cylinder, but the working fluid flows out of the wheel cylinder through the pressure reducing valve, so that the braking force is released.

  The conventional brake ECU 12 obtains an operation request from the collision determination ECU 11 and performs control such as applying light braking or sudden braking. In this embodiment, the brake ECU 12 determines the possibility of collision from the TTC and the lateral position, and starts braking.

  The brake ECU 12 monitors the rotational speed of each wheel, and if there is a locked wheel, the brake ECU 12 reduces the wheel cylinder pressure of the wheel, and similarly suppresses the locking of the wheel at the start. Perform TRC (Traction Control) control. In addition, when it is detected that the vehicle is skidding from the yaw rate of the running vehicle, deceleration by the G sensor, etc., the wheel cylinder pressure of the outer and inner wheels and the front and rear wheels with respect to the turning direction are individually controlled. Thus, VSC control is performed to reduce the side slip of the vehicle.

  The meter buzzer 14 sounds various display devices and buzzer sounds on the meter panel. The meter panel warns the driver that there is a risk of collision with an object by lighting or blinking an icon on a liquid crystal display or displaying a message. In addition, the driver is warned by turning on or blinking a warning lamp. The meter buzzer 14 warns the driver by sounding a warning sound or outputting a voice message that there is a possibility of a collision.

  In addition, the brake ECU 12 may prepare for a collision by winding up the seat belt or moving the seat position of the driver.

  FIG. 5 shows an example of a functional block diagram of the brake ECU 12. The brake ECU 12 is equipped with a microcomputer, and provides each function described above and each function described later by the microcomputer. The microcomputer includes a CPU, a RAM, a ROM, a CAN controller, an input / output interface, and the like. Various actuators including a sensor, a switch, a brake ACT, and a meter buzzer 14 are connected to the input / output interface. In addition, the microcomputer has a general configuration.

  In the brake ECU 12, the CPU executes a program stored in the ROM, and cooperates with the hardware, whereby the lateral G determination unit 21, the lateral position reference value determination unit 22, the lateral position determination unit 23, the TTC count unit 24, the collision The determination unit 25 and the ACT control unit 26 are realized. The brake ECU 12 has a MAP unit 27.

  The lateral G determination unit 21 refers to the alarm MAP or the braking MAP of the MAP unit 27 based on the speed of the object, and determines the lateral G upper limit value.

  FIG. 6 is an example of a diagram schematically illustrating the alarm MAP and the braking MAP. In the braking MAP, a lateral G upper limit value that is larger than the proportional relationship with the speed of the object is associated. In the alarm MAP, a lateral G upper limit value that is the same as or slightly larger than the proportional relationship is associated with the speed of the object.

The braking MAP is calculated in advance by a developer or the like in the following manner and registered in the MAP unit 27, for example. The lateral G upper limit value of the braking MAP is the lateral G obtained from the maximum steering amount that the driver of the preceding vehicle operates to avoid a collision with the object.
Horizontal G upper limit = Yr_max × V
Yr_max is the maximum value of the object yaw rate, and V is the speed of the object. Yr_max is obtained as follows.
Yr_max = (V * Str_max) / nL * 1 / {1+ (V / Vc) ^ 2}
Str_max: Maximum steering amount of the object n: Steering gear ratio L: Wheelbase length Vc: Specific speed (Vc = √ (1 / Kh))
n, L, and Kh can be obtained from general vehicle specifications. The vehicle specifications of the preceding vehicle are stored in advance in the host vehicle or received from the preceding vehicle by inter-vehicle communication or the like. The maximum steering amount Str_max of the object is tested as the maximum value that can be steered by the driver of the preceding vehicle while the collision determination ECU 11 updates the collision determination target information or during the time from the current TTC to the operation TTC. Sought after. Therefore, it is possible to appropriately predict the lateral G due to the avoidance operation due to the high possibility of collision according to the vehicle speed.

  On the other hand, the alarm MAP obtains the steering amount maximum value Str_max as a smaller value. For example, it can be obtained in the same manner as the braking MAP by using the steering amount of the driver of the general preceding vehicle instead of the maximum value that can be steered by the driver of the preceding vehicle. This is because when the TTC is close to the braking operation TTC, it is assumed that the driver performs the maximum avoidance steering, whereas the emergency is low at the time of warning, so it is assumed that the steering is not operated so quickly. Because.

  Thus, the necessary and sufficient lateral G upper limit value can be determined by preparing the MAP corresponding to the vehicle situation. The driver of the preceding vehicle visually observes the rearview mirror and notices the rear vehicle and steers it. Alternatively, the preceding vehicle is equipped with a rear radar and a camera that captures the rear, and these warn the driver of the preceding vehicle and the in-vehicle device according to the TTC with the rear vehicle (own vehicle). Alternatively, the rear vehicle may notify the preceding vehicle of TTC by inter-vehicle communication or the like, and the in-vehicle device of the preceding vehicle may warn the driver of the preceding vehicle or notify the in-vehicle device. Accordingly, the driver of the preceding vehicle and the in-vehicle device can perform avoidance steering in order to avoid a collision with the rear vehicle.

  When the object does not move, that is, when the object is a feature such as a guardrail or a utility pole, the lateral G upper limit value is also zero because the maximum steering amount Yr_max is zero. Moreover, although a pedestrian etc. move, since a moving speed is slow compared with a vehicle, you may consider that the horizontal G upper limit is zero.

  Thus, the alarm MAP and the braking MAP requested by the developer or the like are stored in the brake ECU 12.

Returning to FIG. 5, the lateral position reference value determining unit 22 determines the lateral position reference value from the lateral G upper limit value. The lateral position reference value is determined in consideration of the possibility of movement of the object in the lateral direction with reference to the standard value.
Lateral position reference value = standard value−target object lateral movement maximum value The standard value is determined in advance, and is, for example, the vehicle width of the host vehicle × about 0.4 to 0.6.
FIG. 7A is an example for explaining the lateral position. The lateral position is the position (x coordinate) of the object in the width direction from the center of the host vehicle. Therefore, it can be expected that the smaller the absolute value of the lateral position (x), the greater the amount of overlap with the host vehicle and the higher the possibility of a collision. When the vehicle width of the host vehicle is 180 cm, 180 × 0.5 = 90 cm is a standard value, for example.

Also, since the lateral position is the center position of the object in the width direction (x-axis direction), if the lateral position is half the vehicle width of the host vehicle, the object overlaps the host vehicle by about half in the vehicle width direction. Will be. The greater the amount of overlap, the higher the chance of a collision. Since the possibility of a collision changes depending on the vehicle width of the host vehicle only in the lateral position, the overlap amount may be obtained from the lateral position. This amount of overlap is called the wrap rate.
Lap rate [%] = (absolute value of lateral position / vehicle width of own vehicle) x 100
Therefore, for example, when the vehicle width of the host vehicle is 180 cm and the lateral position is 90 cm, the lap rate is 50%. You may determine that the possibility of a collision is high from the lap rate.

  FIG. 7B is an example of a diagram for explaining the maximum object lateral movement value. The object lateral movement maximum value is a movement amount in a predetermined time when it is assumed that the object has moved at the lateral G upper limit value. Since the reference value is determined assuming the lateral position when the operation TTC is reached, the predetermined time is the time from the current TTC to the operation TTC.

Further, since the lateral G upper limit value is obtained, the lateral movement amount can be obtained by integrating the lateral G upper limit value twice.
Maximum lateral movement of object = Vy × t + (1/2) × horizontal G upper limit × t ^ 2
t: Time (current TTC-actuated TTC)
Vy: Object lateral velocity The lateral position reference value determination unit 22 may obtain the maximum object lateral movement value from the MAP as shown in FIG.

  Returning to FIG. 5, the lateral position determination unit 23 compares the lateral position reference value with the lateral position to determine whether or not there is a possibility of collision with the object. Since this lateral position reference value is obtained by restricting the amount of lateral movement of the object in a necessary and sufficient manner depending on the situation, it is a value that can determine the possibility of collision in the lateral direction during TTC interpolation without excess or deficiency. It has become.

  If the TTC count unit 24 determines that the lateral position determination unit 23 may collide with the object, the TTC count unit 24 stores the TTC received from the collision determination ECU 11 as the final reception TTC. When receiving a TTC, the last received TTC is not below the active TTC. Then, the TTC count unit 24 starts the timer counting with reference to the time when the TTC is received from the collision determination ECU 11. Since the brake ECU 12 repeats the calculation in, for example, a 5 millisecond cycle, the count value of the timer increases by 5 milliseconds. Therefore, if the value obtained by subtracting the count value of the timer from the last reception TTC becomes smaller than the operation TTC, it can be determined that the actuator operation timing is reached.

The collision determination unit 25 acquires the count value of the timer and the last reception TTC, and compares it with the operating TTC to determine whether or not the collision is inevitable. The braking operation TTC is, for example, 0.6 seconds.
Reception TTC-timer count value <operation TTC → collision unavoidable When the collision determination unit 25 determines that a collision is unavoidable, the ACT control unit 26 controls the brake ACT so that sudden braking is applied, and the wheel cylinder pressure is reduced. Increase pressure. By such control, the vehicle can be braked with a delay of at most 5 milliseconds with respect to 0.6 seconds of the operation TTC.

The alarm operation TTC is, for example, 1.0 second.
Received TTC-timer count value <operation TTC → alarm timing When the collision determination unit 25 determines that the alarm timing is reached, the ACT control unit 26 outputs an alarm instruction to the meter buzzer 14 for visual or audible warning. The driver is warned by at least one of the following.

[Operation procedure]
FIG. 8 is a flowchart showing an example of operation procedures of the collision determination ECU 11 and the brake ECU 12.

  The collision determination ECU 11 transmits to the brake ECU 12 the collision determination target information of the object determined to have the highest possibility of collision every 30 milliseconds, for example (S-1). Thereafter, the collision determination ECU 11 searches the target information output by the sensors 10 in the next 30 milliseconds for an object having a high possibility of collision, and performs the same processing.

  The brake ECU 12 performs the illustrated process at intervals of, for example, 5 milliseconds. First, collision determination target information is received (S10).

  The lateral G determination unit 21 determines whether or not TTC is greater than the threshold value 1 (S20). This determination is for determining whether it is an alarm timing. In the present embodiment, the threshold 1 can be the alarm activation TTC because the purpose is to suppress the operation delay even if TTC <operation TTC during the calculation period (30 milliseconds) of the collision determination ECU 11. . For example, if the alarm activation TTC is 1.0 second, the threshold value 1 is 1.0 second.

  When TTC is larger than the threshold value 1 (Yes in S20), the lateral G determination unit 21 determines the lateral G upper limit value from the alarm MAP (S30).

  When TTC is not larger than the threshold value 1 (No in S20), the lateral G determination unit 21 determines whether or not TTC is larger than the threshold value 2 (S40). This determination is for determining whether or not it is a braking timing. As in step S20, the threshold value 2 can be set to the braking operation TTC in order to suppress a delay in the braking operation timing. For example, when the braking operation TTC is 0.6 seconds, the threshold value 2 is 0.6 seconds.

  When TTC is larger than the threshold value 2 (Yes in S40), the lateral G determination unit 21 determines the lateral G upper limit value from the braking MAP (S50). Since the braking G MAP has a larger lateral G upper limit value relative to the speed of the object than the warning MAP, the lateral position reference value can be made smaller than that during the warning.

  If TTC is not greater than the threshold value 2 (No in S40), TTC is equal to or less than the operating TTC, so the brake ECU 12 immediately controls the brake ACT to brake the vehicle.

Next, the lateral position reference value determining unit 22 determines the lateral position reference value (S60). The lateral position reference value is a value obtained by subtracting the maximum object lateral movement value from the standard value. The maximum object lateral movement value is determined from the lateral G upper limit value as described above.
Since the lateral position reference value is smaller at the time of braking than at the time of warning, the judgment criterion becomes stricter during braking in which the preceding vehicle is largely steered away, and unnecessary braking operation can be reduced.
-Since the criterion for the lateral position reference value becomes stricter as the vehicle speed increases, unnecessary operations can be reduced in consideration of the extent to which the object moves in the lateral direction according to the vehicle speed.

  The lateral position determination unit 23 determines whether or not the lateral position of the collision determination target information is smaller than the lateral position reference value (S70).

When the lateral position is smaller than the lateral position reference value (Yes in S70), the TTC count unit 24 sets the TTC included in the collision determination target information as the final reception TTC and starts counting up the timer (S80). . The initial value of the count value of the timer is zero, and the increment of the count up is 5 milliseconds of the calculation cycle.
Timer count value = Timer count value + 5 milliseconds
Then, the collision determination unit 25 determines whether or not the difference between the last reception TTC and the count value of the timer is less than the operation TTC (S90). There are two types of operation TTCs, an alarm operation TTC and a brake operation TTC. The ACT control unit 26 switches the actuator to be operated depending on which operation TTC is satisfied.

  When the difference between the last reception TTC and the timer value is less than the operation TTC (Yes in S90), the ACT control unit 26 determines whether or not there is an avoidance operation by the driver (S100). The driver's avoidance operation is performed by steering or depressing a brake pedal. The ACT control unit 26 detects the steering amount and steering direction of the driver by the steering sensor, the master cylinder pressure by the master cylinder pressure sensor, and the state of the stop lamp switch by the stop lamp switch. If the stop lamp switch is ON and the master cylinder pressure or the steering amount is equal to or greater than a certain value, it is determined that there is an avoidance operation. Alternatively, when the change amount of the master cylinder pressure or the steering amount is a certain value or more, it is determined that there is an avoidance operation. When there is an avoidance operation, unnecessary operation can be prevented by not operating the actuator.

  When there is no avoidance operation (Yes in S110), the ACT control unit 26 outputs an operation request to the brake ACT or outputs an operation request to the meter buzzer 14 (S120).

  When the process of FIG. 8 is completed without operating the actuator, the brake ECU 12 repeats the processes after step S20 at intervals of 5 milliseconds. For this reason, the count value of the timer increases by 5 milliseconds. Therefore, before receiving the collision determination target information from the collision determination ECU 11 next time, the determination in step S110 is Yes, so that the brake ACT can be operated.

  As described above, in the damage reduction system 100 of this embodiment, when the brake ECU interpolates TTC, the lateral position reference value is determined in consideration of the steering amount of the driver of the preceding vehicle according to TTC. The severity of the position reference value can be sufficiently and sufficiently suppressed. Further, even when the lateral position reference value is tightened, when it is necessary to alarm or brake, since the operation delay is suppressed by interpolating the TTC, the effect can be sufficiently exhibited.

  In this embodiment, a damage reduction system 100 will be described in which a part of the function of the brake ECU 12 is replaced by the collision determination ECU 11 and executed.

  FIG. 9 shows an example of a functional block diagram of the collision determination ECU 11 and the brake ECU 12 of the present embodiment. In this embodiment, the collision determination ECU 11 includes a lateral G determination unit 21, a lateral position reference value determination unit 22, a lateral position determination unit 23, and a collision predetermination unit 31, and the brake ECU 12 includes a TTC count unit 24, a collision determination unit, 25 and the ACT control unit 26. Although the function of each functional block is substantially the same as that of the first embodiment, the information transmitted from the collision determination ECU 11 to the brake ECU 12 is different from that of the first embodiment because the functions are divided. The collision determination ECU 11 of the present embodiment transmits the TTC remaining time and the collision determination advance flag to the brake ECU 12.

The TTC remaining time is a difference between the last reception TTC and the operation TTC. In the case of the present embodiment, the final reception TTC is the TTC calculated last by the collision determination ECU 11.
TTC remaining time = last received TTC−actuated TTC
Therefore, for example, when the last reception TTC is 0.62 seconds and the operation TTC is 0.60 seconds, the remaining TTC time is 0.02 seconds. The collision pre-determination unit 31 calculates the TTC remaining time.

  The collision determination prior flag is a flag indicating that the TTC remaining time is shorter than the calculation period of the collision determination ECU 11. In other words, in the next calculation cycle of the collision determination ECU 11, the flag is turned ON when there is a possibility that the TTC is less than the operation TTC.

TTC remaining time <calculation cycle → collision judgment advance flag ON
For example, when the TTC remaining time is 0.02 seconds and the calculation cycle is 30 milliseconds (0.03 seconds), the collision determination advance flag is turned ON. The collision predetermination flag is set to ON by the collision predetermination unit 31.

  The brake ECU 12 has a TTC count unit 24 and counts a timer, which is counted in advance flag ON time. The advance flag ON time is a time counted up when the collision determination advance flag is ON.

  FIG. 10 is a flowchart showing an example of operation procedures of the collision determination ECU 11 and the brake ECU 12.

  The collision determination ECU 11 receives all target information from the sensor unit 10 (S-2). The collision determination ECU 11 identifies an object determined to have the highest possibility of collision, and performs the following processing. Since the processing in steps S20 to S70 is the same as that in the first embodiment, description thereof is omitted.

  Next, when the lateral position is smaller than the lateral position reference value (Yes in S70), the pre-collision determination unit calculates the TTC remaining time and sets a collision determination advance flag (S75). The collision determination ECU 11 transmits the remaining TTC time and the collision determination advance flag to the brake ECU 12 (S76).

  The brake ECU 12 receives the TTC remaining time and the collision determination advance flag from the collision determination ECU 11 (S210).

  Then, the TTC count unit 24 determines whether or not the collision determination advance flag is ON (S220).

  When the collision determination advance flag is ON (Yes in S220), the TTC remaining time is less than the calculation cycle of the collision determination ECU 11, and therefore the TTC count unit 24 starts counting the advance flag ON time (S230). The advance flag ON time is also increased by 5 milliseconds, which is the calculation cycle of the brake ECU 12.

  Then, the collision determination unit 25 determines whether or not the advance flag ON time is longer than the TTC remaining time (S240).

  When the advance flag ON time becomes larger than the TTC remaining time (Yes in S240), it means that the TTC has become an operation TTC. Therefore, the collision determination unit 25 determines that there is no driver avoidance operation (S250). Then, the actuator is operated (S260).

  In the present embodiment, the collision determination ECU 11 performs processing with little trouble even when the calculation cycle is long, and the brake ECU 12 performs TTC interpolation. The lateral position reference value is predicted by predicting the lateral position of the object from the vehicle speed and the steering range. Is the same as that of the first embodiment. Therefore, the effect of suppressing the operation delay by interpolating TTC as in the first embodiment can be sufficiently obtained.

10 Sensor part 11 Collision judgment ECU
12 Brake ECU
13 Brake ACT
14 Meter buzzer 21 Lateral G determination unit 22 Lateral position reference value determination unit 23 Lateral position determination unit 24 TTC count unit 25 Collision determination unit 26 ACT control unit 27 MAP unit 31 Pre-collision determination unit 100 Damage reduction system

Claims (9)

An object detection device that detects an object, an arrival time calculation device that calculates an arrival time to the object, an apparatus control device that evaluates the arrival time and controls a reduction device for collision damage with the object; A collision damage reduction system comprising:
The device control device comprises:
A lateral position criterion for determining whether or not the lateral position of the object collides with the host vehicle when the arrival time is less than or equal to a threshold value, which is smaller than when the arrival time is greater than the threshold value Value adjustment means;
When the lateral position of the object is smaller than the reference value adjusted by the lateral position reference value adjusting means, an elapsed time counting means for counting the elapsed time from when the arrival time is acquired from the arrival time calculating device;
Avoidance device control means for starting control of the avoidance device when the time obtained by subtracting the elapsed time from the arrival time is equal to or less than the threshold;
The collision damage reduction system characterized by having. The lateral position reference value adjusting means estimates that when the arrival time is less than or equal to the threshold, the amount of lateral movement of the object is greater than when the arrival time is greater than the threshold,
When the arrival time is less than or equal to the threshold, the reference value is adjusted to a smaller value than when the arrival time is greater than the threshold.
The collision damage reduction system according to claim 1. The lateral position reference value adjusting means estimates that when the arrival time is equal to or less than the threshold, the steering amount of the driver of the preceding vehicle that is the object is larger than when the arrival time is greater than the threshold.
The collision damage reducing system according to claim 2. The lateral position reference value adjusting means estimates that the amount of movement of the object in the lateral direction increases as the speed of the object relative to the road surface increases.
The reference value is adjusted to a smaller value as the speed of the object with respect to the road surface increases.
The collision damage reducing system according to claim 1 or 2, characterized in that The lateral position reference value adjusting means calculates a lateral movement amount of the object within a time difference between the arrival time and the threshold value.
The collision damage reducing system according to any one of claims 2 to 4, wherein the system is a collision damage reducing system. The period in which the arrival time calculating device transmits the arrival time is longer than the period in which the device control apparatus evaluates the arrival time.
The elapsed time counting means counts up the elapsed time for each evaluation period of the device control device,
The collision damage reduction system according to any one of claims 1 to 5, wherein A collision damage reduction system comprising: an object detection device that detects an object; an arrival time calculation device that calculates an arrival time to the object; and a device control device that controls an apparatus for reducing collision damage with the object. There,
The arrival time calculation device comprises:
A lateral position criterion for determining whether or not the lateral position of the object collides with the host vehicle when the arrival time is less than or equal to a threshold value, which is smaller than when the arrival time is greater than the threshold value Value adjustment means;
Difference calculating means for calculating a difference between the arrival time and the threshold and transmitting the difference to the device control device;
The device control device comprises:
An elapsed time counting means for counting an elapsed time from the time when the difference is acquired from the arrival time calculating device;
An avoidance device control means for starting control of the avoidance device when the elapsed time becomes larger than the difference,
A collision damage reduction system characterized by this. An apparatus control device that is connected via a network to an arrival time calculation device that calculates an arrival time to an object detected by the object detection device, and that controls the collision damage reduction device with the object by evaluating the arrival time Because
A lateral position criterion for determining whether or not the lateral position of the object collides with the host vehicle when the arrival time is less than or equal to a threshold value, which is smaller than when the arrival time is greater than the threshold value Value adjustment means;
When the lateral position of the object is smaller than the reference value adjusted by the lateral position reference value adjusting means, an elapsed time counting means that counts an elapsed time from when the arrival time is acquired from the arrival time calculating device;
Avoidance device control means for starting control of the avoidance device when the time obtained by subtracting the elapsed time from the arrival time is equal to or less than the threshold;
A device control device comprising: An object detection device that detects an object, an arrival time calculation device that calculates an arrival time to the object, and a device control device that controls the collision damage reduction device with the object by evaluating the arrival time A collision damage reduction method to be executed,
When the arrival time is equal to or less than a threshold, the arrival time is adjusted by a reference value for determining whether the lateral position of the object collides with the host vehicle. Less than if greater than the threshold,
The elapsed time counting means, when the lateral position of the object is smaller than the reference value adjusted by the lateral position reference value adjusting means, counting the elapsed time from when the arrival time is acquired from the arrival time calculating device When,
A step of avoiding device control means starting control of the avoiding device when the time obtained by subtracting the elapsed time from the arrival time is equal to or less than the threshold;
A collision damage reduction method comprising:

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