JP2019158778A - Collision avoidance control device - Google Patents

Abstract

To reduce implementation of collision avoidance control with an upward structure wrongly recognized as an obstacle.SOLUTION: A driving assist ECU 10 is configured to, as to a target detected by a radar,: determine whether a first condition (S11) where the target is detected for the first time at a distance from the radar to the target being equal to or less than a preset setting distance, a second condition (S12) where it is estimated that the target is a moving object on the basis of an estimation absolute speed of the target to be computed from a vehicle speed of an own vehicle and a relative speed of the target with respect to the own vehicle, and a third condition (S13) where radio wave intensity of a reflection wave of the target is equal to or less than preset setting intensity are established; and suppress an action of a PCS (S14) with respect to the target determined that the first condition, the second condition and the third condition are established.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a collision avoidance control device that performs collision avoidance control, which is control for avoiding a collision between a host vehicle and an obstacle, based on target information that is target information detected by a radar.

  Conventionally, radar transmits a radio wave in front of the host vehicle, detects a target in front of the host vehicle based on the reflected wave of the radio wave, and determines that the target may collide with the host vehicle. In such a case, a collision avoidance control device that performs collision avoidance control such as warning and automatic braking is known. Patent Document 1 proposes a technique for preventing an upper structure from being detected as an obstacle when an upper structure (for example, a pedestrian crossing bridge) through which the vehicle can pass under is detected from a distance. .

JP 2014-6071 A

  By the way, when traveling in a tunnel formed along the traveling direction of the host vehicle or under an overpass, there is a possibility that an upper structure such as a beam formed thereon is detected as an object of collision avoidance control. is there. For example, as shown in FIG. 2, when the host vehicle travels through a tunnel, the radio wave transmitted by the radar 20 is reflected by a beam A (referred to as an upper structure A) formed on the ceiling of the tunnel. The reflected wave may be detected by the radar R. In this case, if the upper structure A is detected by the radar 20 from the stage where the host vehicle is not approaching the upper structure A, that is, from the stage where the upper structure A is far away from the front of the host vehicle. The collision avoidance control device can prevent the upper structure A from being subject to collision avoidance control.

  However, the upper structure formed in the tunnel or overpass may be detected suddenly when it is considerably close to the host vehicle. In the apparatus proposed in Patent Document 1 described above, it is impossible to prevent the upper structure from being subject to collision avoidance control in such a situation.

  If the absolute velocity of the target can be accurately detected, it can be determined whether the target is a stationary object or a moving object. For an upper structure (stationary object) located above the course of the host vehicle Therefore, it is possible not to be subject to collision avoidance control.

However, in the collision avoidance control device, the target is detected with high resolution in the horizontal direction (left and right direction), but high resolution is not required in the vertical direction, so the vertical direction of the target with respect to the reference axis of the radar is not required. Angle detection accuracy is low. For this reason, the absolute velocity of the target detected in front of the vehicle is detected by the vehicle speed sensor as shown in the following equation, without using the vertical angle (detection elevation angle) of the target with respect to the radar reference axis. Vehicle speed (referred to as own vehicle speed) and the relative speed detected by the radar (see the following equation). This estimated value is called an estimated absolute speed.
Estimated absolute speed = own vehicle speed + relative speed

  If the radar can detect the upper structure from a distance, since the elevation angle (actual elevation angle) is small, the estimated absolute speed calculated by the above formula is almost equal to the actual absolute speed, so it is close to zero. . For this reason, the collision avoidance control device can recognize the upper structure as a stationary object. However, when the upper structure is detected by the radar when the host vehicle is very close to the upper structure, the actual elevation angle increases as the host vehicle approaches the upper structure. The calculated estimated absolute speed does not become a value near zero. For this reason, the collision avoidance control device does not recognize the upper structure as a stationary object. In particular, as shown in FIG. 2, the upper structure A formed in a tunnel or overpass is continuously provided, so the radar target detection reliability is high, and they can be excluded from obstacles. difficult.

  For this reason, collision avoidance control may operate more than necessary.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to reduce the occurrence of collision avoidance control by erroneously recognizing an upper structure as an obstacle.

In order to achieve the above object, the feature of the collision avoidance control device of the present invention is:
It is mounted on the host vehicle, transmits a radio wave in front of the host vehicle, receives a reflected wave of the radio wave, detects a target existing in front of the host vehicle based on the reflected wave, and detects the detected object. A radar (20) that outputs target information that is information of the target;
Collision avoidance control, which is a control for recognizing a target that may collide with the host vehicle as an obstacle based on the target information output from the radar and preventing the host vehicle from colliding with the obstacle. In the collision avoidance control device comprising the collision avoidance control means (10) to be implemented,
For the target detected by the radar, the first condition that the distance from the radar to the target is detected for the first time below a preset set distance, the vehicle speed of the host vehicle and the target vehicle with respect to the host vehicle A second condition that the target is estimated to be a moving object based on the estimated absolute velocity of the target calculated from the relative velocity, and a setting in which the radio wave intensity of the reflected wave of the target is set in advance. Determination means (S11, S12, S13) for determining whether or not the third condition that the intensity is less than or equal to is satisfied;
Collision avoidance control suppression means (S14) that suppresses the execution of the collision avoidance control by the collision avoidance control means for a target that is determined to satisfy the first condition, the second condition, and the third condition. ) And.

  The collision avoidance control apparatus of the present invention includes a radar and a collision avoidance control means. The radar is mounted on the host vehicle, transmits a radio wave in front of the host vehicle, receives a reflected wave of the radio wave, detects a target existing in front of the host vehicle based on the reflected wave, and detects the detection. The target information that is target information is output to the collision avoidance control means. The target information includes, for example, the distance between the radar and the target, the relative speed of the target with respect to the radar (= the relative speed of the target with respect to the vehicle), the direction of the target with respect to the reference axis of the radar, and the reflected wave The radio field strength is included. The collision avoidance control means is a control for recognizing a target that may collide with the host vehicle as an obstacle based on the target information output from the radar and avoiding the host vehicle from colliding with the obstacle. Implement collision avoidance control.

  For example, the collision avoidance control means, based on the distance between the radar and the target, and the relative speed of the target with respect to the radar, the predicted collision time (= (Distance / relative speed) is calculated. The collision prediction time can be used as an index value representing the high possibility that the host vehicle will collide with a target. The collision avoidance control means recognizes the target as an obstacle when the predicted collision time is equal to or less than a threshold, and performs collision avoidance control that is a control for avoiding the own vehicle colliding with the obstacle. . For example, the collision avoidance control means implements an alarm for the driver of the host vehicle, automatic brake control that is a control for generating a braking force on the wheels without requiring the driver's brake operation. Further, for example, the collision avoidance control means prevents the target from being recognized as an obstacle when it can be determined that the target is a stationary object and does not exist on the course of the host vehicle.

  The upper structure formed in the tunnel or overpass may be detected suddenly when it is quite close to the host vehicle. In such a case, the collision avoidance control device may erroneously recognize the upper structure as an obstacle, and unnecessary collision avoidance control may be performed. Therefore, the present invention includes determination means and collision avoidance control suppression means.

  The determination means includes a first condition that the distance from the radar to the target is detected for the first time when the target is detected by the radar, and the vehicle speed of the host vehicle and the target vehicle with respect to the host vehicle. Based on the second condition that the target is estimated to be a moving object based on the estimated absolute speed of the target calculated from the relative speed, and the radio wave intensity of the reflected wave of the target is less than or equal to a preset set intensity It is determined whether or not the third condition is established.

  The first condition is satisfied if the target is detected for the first time when the distance from the radar is equal to or less than a preset set distance. If the target is estimated to be a moving object based on the estimated absolute speed of the target calculated from the vehicle speed of the host vehicle and the relative speed of the target to the host vehicle, the second condition is satisfied. . If the radio wave intensity of the reflected wave is not more than a preset set intensity, the third condition is satisfied.

  The set distance and the set intensity are set to values for distinguishing an upper structure that may be erroneously recognized as an obstacle from other targets. By using this first condition, it is possible to extract a target that is estimated to be an upper structure that is suddenly detected when approaching the host vehicle from a target detected by the radar by narrowing down to some extent. .

  For upper structures that are detected suddenly when approaching the host vehicle, if the estimated absolute speed of the target is calculated from the vehicle speed of the host vehicle and the relative speed of the target to the host vehicle, the target Is estimated as a moving object. In this case, for example, a target whose estimated absolute speed is equal to or higher than a preset moving object determination speed can be estimated as a moving object. In addition, the vehicle speed of the host vehicle should just acquire the value detected by the vehicle speed sensor, and a relative speed can be acquired from target information. The estimated absolute speed of the target can be calculated from the sum of the vehicle speed of the host vehicle and the relative speed of the target with respect to the host vehicle.

  In addition, for the upper structure that is detected suddenly when approaching the host vehicle, the elevation angle that represents the vertical angle of the target detected by the radar is large, so the radio wave intensity of the reflected wave reflected by the radar is small.

  Therefore, by determining whether the first condition, the second condition, and the third condition are met, the upper structures that may be erroneously recognized as obstacles are appropriately narrowed down from the targets detected by the radar. Can be extracted.

  The collision avoidance control suppression unit suppresses the execution of the collision avoidance control by the collision avoidance control unit for a target that is determined to satisfy the first condition, the second condition, and the third condition. The execution of the collision avoidance control refers to an operation for avoiding that the host vehicle collides with an obstacle.

  “Suppressing the execution of the collision avoidance control” includes prohibiting the execution of the collision avoidance control. Further, in order to suppress the execution of the collision avoidance control, the execution of the collision avoidance control may be partially prohibited. For example, the collision avoidance control suppression unit refers to the determination result of the presence or absence of an obstacle based on detection information from another target detection sensor (for example, a camera sensor) different from the radar, and the other target detection sensor detects the obstacle. The collision avoidance control is prohibited in the situation where no object is detected, and the collision avoidance control is not prohibited in the situation where the obstacle detection is detected by the target detection sensor. May be suppressed.

  As a result, according to the present invention, it is possible to reduce the occurrence of collision avoidance control by erroneously recognizing the upper structure as an obstacle.

  If the control of the collision avoidance control is suppressed as described above, the robustness of the control system may be reduced (the occurrence of an unexpected event occurs because the frequency of the execution of the collision avoidance control becomes too high). In the case where there is a risk of such a situation, the target that is a target for suppressing the execution of the collision avoidance control may be further limited.

  For example, the second condition is estimated to be a moving object in which the estimated absolute speed of the target calculated from the vehicle speed of the host vehicle and the relative speed of the target with respect to the host vehicle is equal to or lower than a preset upper limit speed. It is good to use this condition. This upper limit speed is a threshold for adjusting the robustness of the collision avoidance control, that is, a threshold for adjusting the frequency at which the execution of the collision avoidance control is suppressed. The upper limit speed may be set to a value set according to the vehicle speed of the host vehicle (for example, a value proportional to the vehicle speed of the host vehicle).

  According to this, in addition to the operational effects of the present invention described above, it is possible to improve the frequency at which the execution of the collision avoidance control is suppressed, and to obtain the operational effect that the occurrence of unexpected events can be reduced. .

  In the above description, in order to assist the understanding of the invention, the reference numerals used in the embodiments are attached to the constituent elements of the invention corresponding to the embodiments in parentheses. It is not limited to the embodiment defined by.

1 is a schematic system configuration diagram of a driving support apparatus according to an embodiment. It is explanatory drawing explaining the reason for which a short-distance ghost target appears. It is explanatory drawing explaining the calculation method of estimated absolute speed. It is a flowchart showing a PCS suppression control routine. It is a graph showing the field intensity characteristic of a radar. It is a flowchart showing the PCS suppression control routine which concerns on a modification. It is explanatory drawing explaining the method of setting the action | operation suppression application range of PCS using the upper limit of estimated absolute speed.

  Hereinafter, a driving support device according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows a schematic configuration of a driving support apparatus 1 according to an embodiment of the present invention. The driving assistance device 1 is mounted on a vehicle (hereinafter, sometimes referred to as “own vehicle” in order to be distinguished from other vehicles). The driving assistance device 1 corresponds to the collision avoidance control device of the present invention.

  The driving assistance device 1 includes a driving assistance ECU 10, a radar 20, a camera sensor 30, a vehicle state sensor 40, a driving operation state sensor 50, a meter ECU 60, a brake ECU 70, and a buzzer 80.

  Each ECU is an electric control unit (Electric Control Unit) including a microcomputer as a main part. In this specification, the microcomputer includes a CPU, a ROM, a RAM, a nonvolatile memory, an interface I / F, and the like. The CPU implements various functions by executing instructions (programs, routines) stored in the ROM. Some or all of these ECUs may be integrated into one ECU.

  The radar 20 is fixed at the front end of the vehicle body and at the center position in the vehicle width direction. The radar 20 of the present embodiment is fixed to the vehicle body member at a position on the back side of an emblem plate provided at the center of the front grill. The radar 20 is not limited to the above position as long as it is provided at a position where an object ahead of the host vehicle can be detected.

  The radar 20 transmits a radio wave to a preset detection area and receives an reflected wave of the transmitted radio wave, thereby detecting an object existing in front of the host vehicle based on the reflected wave. When reflected waves are collected and detected, it can be estimated that an object is present at the position where the reflected waves are gathered. The object detected by the reflected wave in this way is called a target.

  The radar 20 is, for example, a millimeter wave radar and employs an FM-CW (Frequency Modulated-Continuous Wave) method or a pulse compression method (referred to as an FCM (Fast Chirp Modulation) method). The relative position (distance and angle) of the target with respect to the radar 20 and the relative speed of the target with respect to the radar 20 are detected.

  The radar 20 includes a transmission unit, a reception unit, a signal processing unit, and a target information generation unit (not shown). The transmitter modulates a reference signal having a preset frequency to generate a signal whose frequency changes with time (referred to as a transmission signal), and the transmission signal (sometimes referred to as a radio wave). Is transmitted from the transmitting antenna to the detection area.

  The radio wave transmitted from the transmitting antenna is reflected when radiated to the object. The receiving unit is an electronic circuit that receives a reflected wave of the radio wave via a receiving antenna. Therefore, the presence of an object can be detected by receiving this reflected wave as a received signal.

  The signal processing unit mixes the transmission signal generated by the transmission unit and the reception signal (reflected wave signal) received by the reception unit, and takes the difference between the frequency of the transmission signal and the frequency of the reception signal to obtain a beat. Generate a signal.

  The receiving unit includes a plurality of receiving antennas. The plurality of receiving antennas are arranged so as to be spaced apart from each other by a predetermined distance in the left-right direction and at a predetermined distance in the vertical direction. A beat signal is generated for each channel (for each receiving antenna). The signal processing unit transmits a radar detection signal including the generated beat signal to the target information generating unit.

  The target information generation unit includes a microcomputer as a main part, and performs a frequency analysis such as a fast Fourier transform on the radar detection signal, whereby the distance from the radar 20 to the target, the direction of the target with respect to the radar 20 (horizontal direction) , The vertical direction (elevation angle)), the relative velocity of the target with respect to the radar 20, and the radio wave intensity of the reflected wave. Information generated (calculated) by the target information generation unit is referred to as target information. The target information generating unit outputs the target information to the driving support ECU 10.

  The driving support ECU 10 performs driving support control that is control for supporting the driving operation of the driver. The driving assistance ECU 40 of the present embodiment performs pre-crash safety control (corresponding to collision avoidance control of the present invention) as driving assistance control. Hereinafter, the pre-crash safety control is referred to as PCS control.

  The driving assistance ECU 10 is connected to the camera sensor 30, the vehicle state sensor 40, the driving operation state sensor 50, the meter ECU 60, the brake ECU 70, and the buzzer 80 in order to perform various driving assistance controls including PCS control.

  The camera sensor 30 includes a camera and an image processing unit (not shown). The camera captures a landscape in front of the host vehicle and acquires image data. The image processing unit detects an object such as a vehicle or a pedestrian existing in front of the host vehicle based on image data obtained by photographing with the camera, and transmits camera detection information as detection information to the driving support ECU 10. To do. An object detected by the camera sensor 30 is also called a target. This camera detection information includes information indicating the distance from the camera to the target, the direction of the target relative to the camera, the relative speed of the target relative to the camera, the size of the target target, the type of target, etc. Yes.

  The vehicle state sensor 40 is a plurality of types of sensors that detect a vehicle state. For example, a vehicle speed sensor that detects a traveling speed of the vehicle, a wheel speed sensor that detects a wheel speed, and before and after detecting acceleration in the front-rear direction of the vehicle. These include a G sensor, a lateral G sensor that detects lateral acceleration of the vehicle, and a yaw rate sensor that detects the yaw rate of the vehicle.

  The driving operation state sensor 50 is a plurality of types of sensors that detect the driving operation state of the driver. For example, an accelerator operation amount sensor that detects the operation amount of the accelerator pedal, and a brake operation amount sensor that detects the operation amount of the brake pedal. A brake switch that detects whether or not the brake pedal is operated, a steering angle sensor that detects the steering angle, a steering torque sensor that detects the steering torque, a winker operation sensor that detects the operation of the winker lever, and a shift position of the transmission For example, a shift position sensor to detect.

  Meter ECU60 is connected to the indicator 61 provided in the front of the driver's seat. The meter ECU 60 controls the display on the display 61 in accordance with the display command transmitted from the driving support ECU 10.

  The brake ECU 70 is connected to the brake actuator 71. The brake actuator 71 is provided in a hydraulic circuit between a master cylinder (not shown) that pressurizes hydraulic oil by the depression force of the brake pedal and a friction brake mechanism 72 provided on the left and right front and rear wheels. The friction brake mechanism 72 includes a brake disc fixed to the wheel and a brake caliper fixed to the vehicle body. The brake actuator 71 adjusts the hydraulic pressure supplied to the wheel cylinder built in the brake caliper in accordance with an instruction from the brake ECU 70, and presses the brake pad against the brake disc by operating the wheel cylinder with the hydraulic pressure, thereby causing friction braking force. Is generated. Therefore, the brake ECU 70 can control the braking force of the host vehicle by controlling the brake actuator 71.

  For example, when receiving a pressurization assistance command from the driving support ECU 10, the brake ECU 70 controls the brake actuator 71 to generate a friction braking force that is greater than a friction braking force generated by a normal brake pedal operation. That is, the ratio of the friction braking force to the depression stroke of the brake pedal is set to be larger than that at the normal time (when no pressurization assistance command is received). Further, for example, when receiving an automatic brake command from the driving support ECU 10, the brake ECU 70 controls the brake actuator 71 to generate a predetermined friction braking force even when there is no brake pedal operation.

  The buzzer 80 is driven according to the ringing command transmitted from the driving support ECU 10, and generates a buzzer sound in a manner specified by the ringing command. The driver is alerted by this buzzer sound.

  Here, the PCS control that is the driving support control performed by the driving support ECU 10 will be described. Since PCS control is well known, it will be briefly described here. Based on the target information transmitted from the radar 20, the driving assistance ECU 10 grasps a target existing in front of the host vehicle and determines the possibility that the host vehicle collides with the target. For example, the driving assistance ECU 10 is based on the distance D from the radar 20 to the target and the relative speed Vr of the target with respect to the radar 20, and the collision is an estimated time from the current time until the host vehicle collides with the target. The predicted time TTC (= D / Vr) is calculated. The predicted collision time TTC is used as an index value indicating the high possibility that the host vehicle will collide with the target. It can be determined that the shorter the predicted collision time TTC, the higher the possibility that the host vehicle will collide with the target (the degree of urgency is high). Further, when it can be determined that the target detected by the radar 20 is a stationary object and does not exist in the course of the host vehicle, the driving support ECU 10 does not recognize the target as an obstacle.

  When the possibility that the host vehicle collides with the target reaches an alarm level (for example, when the predicted collision time TTC decreases to the alarm level), the driving support ECU 10 recognizes the target as an obstacle and In addition to ringing intermittently, the display 61 displays “Brake!” To alert the driver. At this time, the driving assistance ECU 10 transmits a pressurization assistance command to the brake ECU 70 to assist the pressurization of the brake hydraulic pressure, thereby enhancing the brake effect when the brake pedal is depressed. When the possibility of the host vehicle colliding with the target is increased and the automatic brake level is reached (for example, when the predicted collision time TTC is further reduced and reaches the automatic brake level), the driving assistance ECU 10 An automatic brake command is transmitted to generate a predetermined friction braking force regardless of the driver's brake operation.

  The driving support ECU 10 can support collision avoidance or reduce damage when a collision occurs by performing such PCS control.

  Further, the driving assistance ECU 10 can grasp a target existing in front of the host vehicle based on not only the radar 20 but also camera detection information output from the camera sensor 30, and the host vehicle can collide with the target. Determine gender. The driving assistance ECU 10 refers to both the determination result of the presence / absence of the obstacle based on the target information output from the radar 20 and the determination result of the presence / absence of the obstacle based on the camera detection information output from the camera sensor 30. Basically, when it is determined that there is an obstacle based on the target information output from the radar 20, the subject vehicle regardless of the determination result of the presence or absence of the obstacle based on the camera detection information. To avoid collision with the obstacle. However, as will be described later, the driving support ECU 10 causes the host vehicle to collide with an obstacle when it is not determined that an object that is subject to PCS operation suppression is based on camera detection information. Do not take action to avoid doing.

  Next, PCS suppression control performed by the driving assistance ECU 10 will be described. The PCS suppression control is a control that suppresses the PCS control from operating by erroneously recognizing the upper structure as an obstacle. Hereinafter, performing an operation (alarm, subsidizing brake hydraulic pressure, automatic braking) that prevents the host vehicle from colliding with an obstacle is referred to as “actuating the PCS”, and the operation is “acting the PCS”. Call it. The operation of the PCS corresponds to “execution of collision avoidance control” in the present invention.

  Here, a situation where the upper structure is easily recognized as an obstacle will be described. As shown in FIG. 2, when the host vehicle is traveling in a tunnel or under an overpass, the radar 20 may detect an upper structure A such as a beam formed on the vehicle. If the upper structure A is detected by the radar 20 from the stage where the host vehicle is not approaching the upper structure, that is, the stage where the upper structure A is far away from the front of the host vehicle, the driving support ECU 10 Can recognize the upper structure A as a stationary object and can prevent it from being subjected to collision avoidance control (PCS operation target).

  For example, it is possible to determine whether the target is a stationary object or a moving object by estimating the absolute velocity of the target. However, in the driving assistance device 1, it is necessary to detect the target with high resolution in the horizontal direction (left and right direction), but high resolution is not required in the vertical direction compared to the horizontal direction (the obstacle is the same as the vehicle). Because they are at the same height). For this reason, the detection accuracy of the radar 20 in the vertical direction is low.

For these reasons, the driving assistance ECU 10 does not use the vertical angle of the target included in the target information output by the radar 20 (the vertical angle of the target with respect to the reference axis of the radar 20: called the elevation angle). As shown in the following equation (1), an estimated absolute velocity Vx that is an estimated value of the absolute velocity of the target is calculated.
Vx = Vs + Vr (1)
Here, Vs is the vehicle speed of the host vehicle detected by the vehicle speed sensor, and Vr is the relative speed of the target with respect to the radar 20 included in the target information (= the relative speed of the target with respect to the host vehicle). The relative speed is expressed as a positive value in the direction in which the target is moving away from the host vehicle, and as a negative value in the direction in which the target is approaching the host vehicle.

Assuming that the actual elevation angle θ of the target with respect to the reference axis of the radar 20 is the actual elevation angle θ, the relative velocity Vr of the stationary object output from the radar 20 as the target information is a value represented by the following equation (2). .
Vr = −Vs · cos θ (2)
Hereinafter, the relative speed Vr is referred to as a radar detection relative speed Vr.

  For example, as shown in FIG. 3A, when the host vehicle is traveling at a speed of 30 km / h, an upper structure A (θ = 9 deg) far from the host vehicle is detected. The radar detection relative speed Vr is −30 × cos (9 deg) = − 29.6 km / h. In this case, the calculation result of the estimated absolute speed Vx is 0.4 km / h (= 30-29.6). Therefore, in such a case, the driving assistance ECU 10 can determine that the upper structure A is a stationary object. Further, it can be determined from the history (time transition) of the target information of the upper structure A that the upper structure A exists above the course of the host vehicle. As a result, the driving assistance ECU 10 can determine that the upper structure A is not an obstacle.

  On the other hand, as shown in FIG. 3B, when the host vehicle is traveling at a speed of 30 km / h, the upper structure A is detected by the radar 20 for the first time when the elevation angle of the upper structure A becomes 50 deg. In this case, the radar detection relative speed Vr is −30 × cos (50 deg) = − 19.3 km / h. In this case, the calculation result of the estimated absolute speed Vx is 10.7 km / h (= 30-19.3).

  As can be seen from these examples, the lower the timing at which the upper structure A is detected, that is, the shorter the distance from the radar 20 to the upper structure A when the upper structure A is first detected, The actual elevation angle θ of the object A increases and the estimated absolute speed Vx increases. Accordingly, since the driving support ECU 10 cannot determine the upper structure A as a stationary object, the driving support ECU 10 may erroneously determine that the upper structure A is a preceding vehicle (obstacle) having a slower traveling speed than the host vehicle. . The lower part of FIG. 2 represents an image in which the upper structure A is erroneously determined as a preceding vehicle having a slower traveling speed than the host vehicle. Moreover, since the upper structure A is continuously provided as shown in the upper part of FIG. 2 (because it is repeatedly detected), the radar 20 has a high reliability of target detection, and these are detected from obstacles. It is difficult to exclude.

  In order to solve such a problem, the driving support ECU 10 performs PCS suppression control.

  Although it is a target that does not need to be recognized as an obstacle, like the upper structure described above, it can be detected suddenly when approaching the host vehicle and it is determined that it is not an obstacle. Difficult targets are called short range ghost targets.

The features common to short range ghost targets are as follows.
1. The target information is generated at a position close to the host vehicle.
2. A moving object is estimated from the estimated absolute speed.
3. The radio wave intensity of the reflected wave reflected from the target is low.

  In the PCS suppression control, it is determined whether or not the target detected by the radar 20 is a short-distance ghost target using characteristics common to the short-distance ghost target. If it is estimated that there is, the PCS operation is suppressed.

  FIG. 4 is a flowchart showing a PCS suppression control routine. The driving assistance ECU 10 repeatedly executes the PCS suppression control routine at a predetermined calculation cycle.

  When the PCS suppression control routine is started, the driving support ECU 10 determines whether or not the target information is generated by the radar 20 within the set distance Dref (within the set distance Dref from the radar 20) by the radar 20 in step S11. That is, it is determined whether or not a new target has been detected within a range within the set distance Dref from the host vehicle.

  The driving assistance ECU 10 grasps the position (distance and direction) of the target every time the target information is output from the radar 20, and is different from the target that has been detected so far, based on the history of the target information. If a new target is detected, it is determined in step S11 whether or not the distance D from the radar 20 to the target is equal to or less than the set distance Dref for the new target. The set distance Dref is a preset distance, and is set to 10 m, for example.

  Even if a new target is not detected, or even if a new target is detected, if the distance D is greater than the set distance Dref, the driving support ECU determines “No” in step S11 and determines the PCS. The suppression control routine is temporarily terminated. The PCS suppression control routine is repeated at a predetermined calculation cycle.

  The determination in step S11 is a determination as to whether or not the first condition of the present invention is satisfied, that is, the target detected by the radar 20 is a set distance in which the distance from the radar 20 to the target is set in advance. This corresponds to the determination as to whether or not the target is detected for the first time.

  If a new target is detected within the range within the set distance Dref from the radar 20 after the PCS suppression control routine is executed one calculation cycle before, the driving assistance ECU 10 determines “Yes” in step S11, and the processing Advances to step S12.

  In step S12, the driving assistance ECU 10 calculates an estimated absolute speed Vx for a target newly detected within a set distance Dref from the host vehicle (referred to as a target), and based on the estimated absolute speed Vx. Whether the target is estimated to be a moving object. Using the above equation (1), the driving assistance ECU 10 adds the own vehicle speed Vs detected by the vehicle speed sensor and the relative speed Vr of the target with respect to the radar 20 included in the target information to estimate the absolute speed Vx ( = Vs + Vr). Then, the driving assistance ECU 10 determines whether or not the estimated absolute speed Vx is equal to or higher than a preset moving object determination speed Vmove. When the estimated absolute speed Vx is equal to or higher than the moving object determination speed Vmove, the driving support ECU 10 estimates that the target is a moving object. The moving object determination speed Vmove is set to a value of about 3 km / h, for example.

  The determination in step S12 corresponds to a determination as to whether or not the second condition of the present invention is satisfied.

  When the driving support ECU 10 estimates that the target is not a moving object (S12: No), the PCS suppression control routine is temporarily ended. On the other hand, when it is estimated that the target is a moving object (the estimated absolute speed Vx is equal to or higher than the moving object determination speed Vmove) (S12: Yes), the driving assistance ECU 10 advances the process to step S13.

  In step S13, the driving assistance ECU 10 determines whether or not the radio wave intensity P of the reflected wave reflected from the target (the radio wave intensity P of the reflected wave received by the radar 20) is equal to or less than the set intensity Pref. The driving support ECU 10 reads the radio wave intensity P from the target information of the target. The set intensity Pref is a preset radio field intensity and is, for example, −5 dB.

  FIG. 5 is a characteristic diagram showing an example of the relationship between the elevation angle of the target detected by the radar 20 (the vertical angle at which the target is detected with respect to the radar axis: deg) and the radio wave intensity of the reflected wave. In the drawing, an area indicated by gray represents an area in the vertical direction in which a transmission signal (radio wave) is transmitted by the radar 20 as an image. In general, radar has directivity. As shown in the figure, the radio wave intensity of the reflected wave decreases as it goes away from zero, but in particular, in a closed space such as a tunnel, the transmission signal transmitted from the radar 20 is reflected in a complex manner and received by the radar 20, In some cases, a reflected wave reflected from an upper structure having a large elevation angle is detected.

  The determination in step S13 corresponds to a determination as to whether or not the third condition of the present invention is satisfied.

  When the radio wave intensity P of the reflected wave of the target exceeds the set intensity Pref (S13: No), the driving support ECU 10 once ends the PCS suppression control routine. On the other hand, when the radio wave intensity of the reflected wave of the target is equal to or lower than the set intensity (S13: Yes), the driving assistance ECU 10 advances the process to step S14.

  In step S14, the driving assistance ECU 10 estimates that the target is a short-distance ghost target, sets the target as a target for suppressing the PCS operation, and temporarily ends the PCS suppression control routine.

  As described above, when the PCS control is performed, the driving assistance ECU 10 determines whether there is an obstacle based on the target information output from the radar 20 and the obstacle based on the camera detection information output from the camera sensor 30. Refer to both the judgment result of the presence or absence of an object. The determination result of the obstacle based on the target information output from the radar 20 is “There is an obstacle”, and the determination result of the presence or absence of the obstacle based on the camera detection information output from the camera sensor 30 is “There is an obstacle”. Case 1 in which the determination result of the obstacle based on the target information is “There is an obstacle”, and the determination result of the presence / absence of the obstacle based on the camera detection information is “No obstacle”, and Case 3 in which the obstacle determination result based on the target information is “no obstacle” and the obstacle determination result based on the camera detection information is “There is an obstacle”, and the obstacle based on the target information The pattern can be divided into a case 4 in which the determination result of the obstacle is “no obstacle” and the determination result of the presence or absence of the obstacle based on the camera detection information is “no obstacle”.

  During the execution of the PCS control, the driving assistance ECU 10 performs the PCS control according to whether or not each target detected by the radar 20 is set as a PCS operation suppression target in the PCS suppression control routine described above. Switch the form.

  In the case 1 and the case 2, the driving support ECU 10 gives priority to the obstacle determination result based on the target information output from the radar 20 for the target that is not set as the PCS operation suppression target. Activates the PCS and does not activate the PCS in cases 3 and 4.

  On the other hand, the operation control ECU 10 operates the PCS in the case of the case 1 for the target (target estimated as a short-distance ghost target) set as the target for suppressing the PCS operation. That is, when the determination result of the presence / absence of the obstacle based on the camera detection information is “no obstacle”, the PCS is not operated (the PCS operation is prohibited for itself). Therefore, in case 2, the PCS does not operate. Thereby, the operation of the PCS is suppressed for the target estimated as the short-range ghost target.

  According to the driving support apparatus 1 of the present embodiment described above, it is possible to reduce the fact that the PCS is activated by erroneously recognizing the upper structure as an obstacle. Further, even if the target is estimated as a short-distance ghost target based on the target information output from the radar 20, it is recognized as an obstacle by the camera detection information output from the camera sensor 30. Since the PCS operates, safety can be improved.

<Modification of PCS suppression control routine>
Next, a modified example of the PCS suppression control routine will be described.
When the PCS operation is suppressed with respect to a short-distance ghost target using the PCS suppression control routine of the embodiment, there is a possibility that the robustness of the control system may be reduced (the frequency at which the PCS operation is suppressed becomes too high). If there is a possibility that an unexpected event may occur), a PCS suppression control routine according to the following modification may be employed. In the PCS suppression control routine according to this modification, the target that is the target for suppressing the operation of the PCS is further limited.

  FIG. 6 is a flowchart showing a PCS suppression control routine according to a modification. The PCS suppression control routine according to this modification performs the determination process of step S12 ′ instead of the determination process of step S12 of the PCS suppression control routine (FIG. 4) of the embodiment. Is the same as the PCS suppression control routine of the embodiment. The same processes as those in the PCS suppression control routine of the embodiment are denoted by common step symbols in the drawings, and description thereof is omitted.

  In step S12 ′, the driving assistance ECU 10 calculates the estimated absolute speed Vx of the target, and is the estimated absolute speed Vx less than or equal to a preset upper limit speed Vlim and greater than or equal to the moving object determination speed Vmove? Determine whether or not. That is, in step S12 ', the driving assistance ECU 10 determines whether the target is a moving object having an estimated absolute speed Vx that is equal to or lower than the upper limit speed Vlim.

  The upper limit speed Vlim is set in advance so as to be determined according to the current host vehicle speed Vs. For example, the upper limit speed Vlim is set to a value that is ½ (half) of the current host vehicle speed Vs. By setting the upper limit speed Vlim to a value proportional to the host vehicle speed Vs, a target that exists in a direction exceeding the predetermined actual elevation angle θ can be excluded from a target for suppressing the operation of the PCS.

  For example, when the upper limit speed Vlim is set to a value that is ½ of the host vehicle speed Vs, as shown in FIG. 7, the direction where the actual elevation angle θ is 60 deg is used as a boundary (cos (60 deg) = 1/2. ), A target having an actual elevation angle θ exceeding 60 deg can be excluded from the target for suppressing the PCS operation.

  If the driving support ECU 10 determines “Yes” in step S12 ′, the process proceeds to step S13 described above. If the driving support ECU 10 determines “No”, the driving support ECU 10 temporarily ends the PCS suppression control routine.

  According to the PCS suppression control routine of the modified example described above, it is possible to improve the frequency at which the PCS operation is suppressed, and to obtain an operational effect that the occurrence of unexpected events can be reduced. Further, without using the vertical angle (elevation angle) of the target detected by the radar 20, the PCS operation is suppressed by using the upper limit value of the estimated absolute speed Vx calculated from the own vehicle speed Vs and the relative speed Vr. Since the upper limit of the elevation angle is determined, it can be carried out with high accuracy.

  Although the collision avoidance control device according to the present embodiment has been described above, the present invention is not limited to the above-described embodiment (including modifications), and various modifications can be made without departing from the object of the present invention. It is.

  For example, in the present embodiment, when the PCS operation is suppressed, the PCS operation is prohibited in the case 2, but the PCS operation may be prohibited in both the case 1 and the case 2, for example. In the present embodiment, the PCS control is performed using the target information output from the radar 20 and the camera detection information output from the camera sensor 30, but the camera detection information is not necessarily used.

  DESCRIPTION OF SYMBOLS 1 ... Driving assistance device, 10 ... Driving assistance ECU, 20 ... Radar, 30 ... Camera sensor, 40 ... Vehicle state sensor, 50 ... Driving operation state sensor, 60 ... Meter ECU, 61 ... Display, 70 ... Brake ECU, 71 ... Brake actuator, 72 ... Friction brake mechanism, 80 ... Buzzer, A ... Upper structure, θ ... Elevation angle.

Claims (1)

It is mounted on the host vehicle, transmits a radio wave in front of the host vehicle, receives a reflected wave of the radio wave, detects a target existing in front of the host vehicle based on the reflected wave, and detects the detected object. A radar that outputs target information that is information of the target;
Collision avoidance control, which is a control for recognizing a target that may collide with the host vehicle as an obstacle based on the target information output from the radar and preventing the host vehicle from colliding with the obstacle. A collision avoidance control device comprising:
For the target detected by the radar, the first condition that the distance from the radar to the target is detected for the first time below a preset set distance, the vehicle speed of the host vehicle and the target vehicle with respect to the host vehicle A second condition that the target is estimated to be a moving object based on the estimated absolute velocity of the target calculated from the relative velocity, and a setting in which the radio wave intensity of the reflected wave of the target is set in advance. Determination means for determining whether or not the third condition that the intensity is less than or equal to is satisfied;
Collision avoidance control suppressing means for suppressing execution of the collision avoidance control by the collision avoidance control means for a target determined to satisfy the first condition, the second condition, and the third condition. A collision avoidance control device provided.

Images