JP7583584B2 - Electronic Control Unit - Google Patents

Description

The present invention relates to an electronic control device that activates a collision mitigation brake.

Patent Document 1 describes an electronic control device that activates a collision damage mitigation brake when the time to collision (TTC: Time to Collision) until the vehicle collides with an object in front of the vehicle falls below a predetermined threshold in order to reduce collisions with objects in front of the vehicle and the damage caused by the collision.

JP 2016-117319 A

When there is a preceding vehicle decelerating near an intersection that includes a branch point, the driver of the following vehicle will slow down their vehicle in response to the deceleration of the preceding vehicle, but this may shorten the TTC until they collide with the preceding vehicle. Also, at ETC gates (ETC gates) for electronic toll collection systems (ETC) installed on expressways and the like, drivers generally slow down their vehicles, but this may shorten the TTC until they collide with the start control rod (opening and closing bar) installed at the ETC gate.

Therefore, in the electronic control device described in Patent Document 1, the collision damage mitigation brake can be activated even when the driver is aware of a situation in which, for example, it is clear that the preceding vehicle is about to turn right or left at an intersection or that the gate is about to open. In other words, for a driver who is aware of the above-mentioned situations, frequent activation of the collision damage mitigation brake and the relatively strong braking that accompanies it can be unpleasant, and there is a risk that the collision damage mitigation brake will be activated excessively.

Therefore, the present invention aims to provide an electronic control device that can prevent excessive activation of the collision damage mitigation brake in certain situations.

Therefore, when the collision time until the vehicle collides with an object located in front of the vehicle becomes equal to or less than a predetermined threshold, the electronic control unit outputs a brake activation signal to activate the collision mitigation brake, acquires the vehicle's current position information and surrounding environment information including map information, and when it determines that the vehicle is approaching an intersection based on the current position information and the surrounding environment information, it suppresses the activation of the collision mitigation brake when all of the following conditions are met based on the imaging results of the imaging element that images the area in front of the vehicle: a first condition that a preceding vehicle is present in the vehicle's driving lane and one of the left or right turn indicators provided at the rear of the preceding vehicle is flashing, a second condition that the preceding vehicle is moving in the direction in which the turn indicator is flashing, a third condition that the ratio of the width of the projection surface of the rear of the preceding vehicle to the width of the driving lane is equal to or less than a predetermined ratio, and a fourth condition that the brake lights provided at the rear of the preceding vehicle are off or the relative speed of the preceding vehicle to the vehicle is 0 or more .

The electronic control unit can prevent excessive activation of the collision mitigation brake in certain situations.

1 is a schematic diagram showing an example of a vehicle equipped with an electronic control device; FIG. 2 is an internal structural diagram showing an example of an electronic control device. 4 is a flowchart showing an example of a periodic process executed by an electronic control unit. 11 is a flowchart showing an example of normal control processing of the regular processing; 4 is a flowchart showing an example of suppression control processing of the regular processing; 13 is a flowchart showing a modified example of the regular processing. 7 is a flowchart showing a part of an example of a suppression flag setting process shown in FIG. 6 . 11 is a flowchart showing a part of an example of the suppression flag setting process. 10A and 10B are diagrams for explaining a process for determining whether a preceding vehicle has started to turn right or left. 13 is a flowchart showing a first modified example of the suppression control process. 13 is a flowchart showing a second modified example of the suppression control process.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.
A vehicle 1 is provided with a collision damage mitigation brake control system 10 including a brake control device 100 and an electronic control device (ECU: Electric Control Unit) 102. The brake control device (hereinafter simply referred to as "brake ECU") 100 and the ECU 102 are connected to each other so as to be able to communicate with each other via a controller area network (CAN). However, instead of the CAN, an in-vehicle network such as FlexRay (registered trademark) or MOST (Media Oriented System Transport) (registered trademark) may be used.

The collision damage mitigation brake control system 10 also includes an object detection unit 104, a current position acquisition unit 106, a vehicle speed detection unit 108, a brake operation detection unit 110, an ETC vehicle unit 112, and an alarm unit 114. The object detection unit 104, the current position acquisition unit 106, the vehicle speed detection unit 108, the brake operation detection unit 110, the ETC vehicle unit 112, and the alarm unit 114 are each connected to the ECU 102 via an in-vehicle network.

The brake ECU 100 electronically controls the service brake. The brake ECU 100 activates the service brake in response to the driver's brake operation or a brake activation signal, which will be described in detail later.

As shown in FIG. 2, the ECU 102 has a built-in microcomputer that is composed of a processor 102A, a non-volatile memory 102B, a volatile memory 102C, an input/output circuit 102D, and a bus 102E that interconnects these.

The processor 102A is hardware that executes various control programs by executing instruction sets written in software programs, and is composed of, for example, a CPU (Central Processing Unit).

The non-volatile memory 102B is a semiconductor memory in which various control programs and the like are stored and which can save various data, and is composed of, for example, an EEPROM (Electrical Erasable Read Only Memory) and a flash ROM (Read Only Memory).

Volatile memory 102C is a semiconductor memory that serves as a temporary storage area, and is composed of, for example, DRAM (Dynamic Random Access Memory) or SRAM (Static Random Access Memory).

The input/output circuit 102D is a device that inputs signals from the object detection unit 104, the current position acquisition unit 106, the vehicle speed detection unit 108, the brake operation detection unit 110, the ETC on-board unit 112, etc., and outputs signals to the brake ECU 100 and the notification unit 114, etc.

The object detection unit 104 is configured to detect at least a distance D to an object, such as an obstacle, located in front of the vehicle 1, and a relative speed Vr (the speed of the object relative to the vehicle 1) calculated based on the time rate of change of the distance D. Examples of the object detection unit 104 include radar such as a millimeter wave radar or a laser radar, a combination of a radar and a monocular camera, or a stereo camera consisting of a pair of left and right CCD (Charge Coupled Device) cameras (or CMOS (Complementary Metal-Oxide Semiconductor) cameras). The object detection unit 104 may also be configured to detect the rate of change of the relative speed Vr, i.e., the relative acceleration.

The current position acquisition unit 106 includes a GPS receiver and a map database. The map database is constructed, for example, in a hard disk drive (HDD) or solid state drive (SSD) mounted on the vehicle 1, and stores surrounding environment information including map information associated with latitude and longitude. The surrounding environment information includes at least shape information and position information of intersections including branch points, position information of stop lines, position information of ETC and ETC road signs, intersection information by V2X (Vehicle-to-Everything), and card insertion confirmation communication device information in front of the ETC gate. An example of such a current position acquisition unit 106 is a car navigation system. The surrounding environment information may be acquired, for example, from an external information data center via a communication device (not shown) mounted on the vehicle 1, and the surrounding environment information can be updated to the latest.

The vehicle speed detection unit 108 may be, for example, a vehicle speed sensor that detects the vehicle speed. The brake operation detection unit 110 detects the brake operation, and may be, for example, a sensor that detects that the brake pedal has been depressed, or a switch that generates a signal to turn on the brake lights (brake lamps (stop lamps)).

The ETC vehicle unit 112 includes an insertion section into which an ETC card can be inserted, and a communication section capable of communicating with an antenna installed in the ETC, and is configured to determine whether or not an ETC card is inserted. In addition, it is preferable that the ETC vehicle unit 112 is capable of determining, for example, whether or not the inserted ETC card has expired, i.e., whether or not the card is valid for opening the start control rod (opening/closing bar) installed at the ETC gate.

The notification unit 114 notifies the driver of predetermined information in response to a signal output from the ECU 102. Examples of the notification unit 114 include a dashboard capable of displaying predetermined information such as a multifunction display, and an alarm capable of emitting a warning sound.

When the object detection unit 104 detects an object located in front of the vehicle 1, the ECU 102 basically first calculates the time to collision TTC (D/Vr, the value obtained by dividing the distance D by the relative speed Vr) until the vehicle 1 collides with the object based on the information detected by the object detection unit 104. Then, the ECU 102 sequentially executes warning control, warning brake control, and collision damage mitigation brake control according to the calculated TTC. Note that the ECU 102 may calculate the TTC by taking into account the relative acceleration in addition to the distance D and the relative speed Vr.

The warning control is executed when the TTC falls below a first threshold Tc1 (e.g., about 2 seconds). More specifically, in the warning control, the processor 102A generates a warning by outputting a signal to the notification unit 114. This notifies the driver that there is a high possibility of a collision.

The warning brake control is executed when the TTC reaches a second threshold Tc2 (e.g., 1.5 seconds) that is a predetermined value smaller than Tc1 when the warning control is executed and the driver does not apply the brakes. More specifically, in the warning brake control, the ECU 102 automatically activates the service brakes by outputting a brake activation signal including information indicating the first deceleration to the brake ECU 100. This notifies the driver that there is a high possibility of a collision. Hereinafter, in this specification, the notification due to the execution of the warning control and the notification due to the execution of the warning brake control are collectively referred to as the occurrence of a warning.

The collision damage mitigation brake control is an emergency brake control that is executed when a certain condition is met in the case where the driver does not apply the brakes even after the warning control and the warning brake control are executed, thereby braking and stopping the vehicle 1 and preventing a collision or collision damage. Hereinafter, the collision damage mitigation brake control is simply referred to as "emergency brake control." More specifically, the emergency brake control is executed when the TTC reaches a third threshold Tc3 (e.g., about 1 second) that is a predetermined value smaller than Tc2. In the emergency brake control, the ECU 102 automatically activates the service brake by outputting a brake activation signal to the brake ECU 100, the brake activation signal including information indicating a second deceleration that is a predetermined value larger than the first deceleration.

The first deceleration in the warning brake control is preset based on the braking performance of the vehicle, for example, about 0.2 G to about 0.4 G. The second deceleration in the emergency brake control is preset based on the braking performance of the vehicle 1, for example, about 0.5 G.

Here, the driver of vehicle 1 approaching the intersection slows down vehicle 1 in response to the deceleration of the preceding vehicle, which is decelerating to turn right or left at the intersection, but the TTC may become shorter because the inter-vehicle distance between vehicle 1 and the preceding vehicle becomes shorter or the relative speed becomes smaller.

In addition, while the driver of vehicle 1 traveling through an ETC gate generally slows down vehicle 1, the distance between vehicle 1 and the gate in front of it may become shorter, or the relative speed may become smaller, resulting in a shorter TTC. Therefore, in a configuration that executes warning control, warning brake control, and emergency brake control based solely on a comparison between the TTC and various thresholds, emergency brake control may be executed in addition to warning control and warning brake control.

However, there are cases where the driver is aware of a situation in which it is clear that the preceding vehicle will deviate from vehicle 1's driving lane by making a right or left turn, or that the ETC card is effective in opening the barrier and the barrier will open. In such cases, the driver is likely not to slow vehicle 1 more than necessary in order to ensure smooth traffic flow, as the possibility of a collision between vehicle 1 and the preceding vehicle or the barrier is low. Therefore, for a driver who is aware of such a situation, the execution of emergency brake control could result in excessive application of the emergency brakes. Furthermore, there is a risk of energy being wasted due to unnecessary application of the emergency brakes.

The ECU 102 is configured to acquire surrounding environment information including current position information and map information, and suppresses the activation of the emergency brake when it determines that the vehicle 1 is approaching an intersection or an ETC gate based on the current position of the vehicle 1 on the map (i.e., the signal output from the current position information acquisition unit 106). The ECU 102 is also configured to similarly suppress the issuance of warnings, including the activation of warning brakes.

An example of the scheduled processing executed by the processor 102A will be described below with reference to Figures 3 to 5. The scheduled processing is triggered when the ignition switch of the vehicle 1 is turned on, and is executed every predetermined time (e.g., 50 ms) when the service brake is not activated. In other words, if the driver voluntarily activates the service brake and a signal indicating the activation of the brake is output from the brake activation detection unit 110, the scheduled processing is forcibly terminated.

In step 10, the processor 102A determines whether or not an object is present in front of the vehicle. For example, the processor 102A determines that an object is present in front of the vehicle when an object is present in the detection area of the object detection unit 104. However, this is not limited to the above, and the processor 102A may determine that an object is present in front of the vehicle when, for example, the distance D from the vehicle 1 to the object is equal to or less than a predetermined distance based on a signal output from the object detection unit 104. Then, if the processor 102A determines that an object is not present in front of the vehicle, it ends the process. On the other hand, if the processor 102A determines that an object is present in front of the vehicle, it proceeds to step 20.

In step 20, the processor 102A sets (initializes) the suppression flag F to 0 (F=0). The suppression flag F is a flag for determining whether or not to suppress the generation of a warning and the operation of the emergency brake, and is set to 1 or 0 depending on the determination result in step 30 described below. Here, the suppression flag F is initially set to 0, and when the suppression flag F=1, the generation of a warning and the operation of the emergency brake are suppressed, and when the suppression flag F=0, the warning control, warning brake control, and emergency brake control are executed as usual.

In step 30, the processor 102A determines whether the vehicle 1 is approaching an intersection or an ETC gate based on the signal output from the current position acquisition unit 106.

Here, processor 102A targets the closest intersection to vehicle 1 among the intersections present in the traveling direction of vehicle 1, for example, based on the current position of vehicle 1 on the map. Then, processor 102A determines that vehicle 1 is approaching the intersection when the distance from vehicle 1 to the stop line or traffic light of the target intersection becomes equal to or less than a first distance. Here, since a vehicle turning right or left at an intersection generally starts to decelerate when the distance from the vehicle to the stop line of the intersection is about 30 m, the first distance is predefined to a value within the range of, for example, about 35 m to about 45 m.

Furthermore, processor 102A determines that vehicle 1 is approaching the ETC gate when, for example, the distance from vehicle 1 to the exit of the ETC gate or the distance to a road marking painted on the road surface near the ETC gate encouraging driving slowly at a speed of approximately 20 km/h becomes equal to or less than a second distance based on the current position of vehicle 1 on the map. Here, the second distance is predetermined to a value within a range of, for example, approximately 10 m to approximately 30 m, but may be the same value as the first distance.

However, the first distance and the second distance may be set arbitrarily by the driver, as long as they are not smaller than a lower limit value that is predetermined, for example, through experiments, etc.

In step 30, if the processor 102A determines that the vehicle 1 is approaching an intersection or an ETC gate, the process proceeds to step 40.

In step 40, processor 102A sets suppression flag F to 1 (F=1).

On the other hand, in step 30, if the processor 102A determines that the vehicle 1 is not approaching either an intersection or an ETC gate, the processor 102A proceeds to step 50. In other words, if the vehicle 1 is not approaching either an intersection or an ETC gate, the processor 102A skips step 40 and does not change the inhibition flag F (F=0).

In step 50, the processor 102A determines whether the suppression flag F is set to 0. If the processor 102A determines that the suppression flag F is set to 0, the processor 102A advances the process to step 60.

In step 60, the processor 102A executes a process for controlling the generation of a normal warning and the activation of the warning brake and emergency brake (hereinafter, simply referred to as "normal control process"). An example of the normal control process will be described with reference to FIG. 4.

In step 202, the processor 102A calculates the TTC by dividing the distance D to the object ahead of the vehicle detected in step 10 by the relative speed Vr of the object with respect to the vehicle 1.

In step 204, the processor 102A determines whether the TTC is equal to or less than Tc1. If the processor 102A determines that the TTC is greater than Tc1, the processor 102A ends the process. On the other hand, if the processor 102A determines that the TTC is equal to or less than Tc1, the processor 102A advances the process to step 206.

In step 206, the processor 102A executes warning control. This notifies the driver that a collision is highly likely. The processor 102A then advances the process to step 208.

In step 208, the processor 102A determines whether the TTC is equal to or less than Tc2. If the processor 102A determines that the TTC is greater than Tc2, it ends the process. In this case, only warning control is executed. On the other hand, if the processor 102A determines that the TTC is equal to or less than Tc2, it advances the process to step 210.

In step 210, the processor 102A determines whether the TTC is equal to or less than Tc3. If the processor 102A determines that the TTC is equal to or less than Tc3, the processor 102A advances the process to step 212.

In step 212, the processor 102A executes emergency brake control. That is, if the TTC is equal to or less than Tc3, both the warning control and the emergency brake control are executed. Then, the processor 102A ends the process.

On the other hand, if in step 210, processor 102A determines that TTC is greater than Tc3, it proceeds to step 214.

In step 214, the processor 102A executes warning brake control. This notifies the driver of the high possibility of a collision by issuing a warning and automatically applying the service brakes. In other words, if the TTC is greater than Tc3 and less than or equal to Tc2, both the warning control and the warning brake control are executed. The processor 102A then terminates the process.

On the other hand, if in step 50, processor 102A determines that suppression flag F is set to 1, it proceeds to step 70.

In step 70, the processor 102A executes a process for suppressing the generation of a warning and the activation of the warning brake and emergency brake (hereinafter, simply referred to as "suppression control process"). An example of the suppression control process will be described with reference to FIG. 5.

In step 302, the processor 102A changes Tc1, Tc2, and Tc3. More specifically, the processor 102A subtracts a first predetermined value from the initial values of Tc1, Tc2, and Tc3.

The first predetermined value is set to, for example, about 0.3 seconds. In this case, if Tc1 has an initial value of, for example, about 2 seconds, it is changed to about 1.7 seconds. Also, if Tc2 has an initial value of, for example, about 1.5 seconds, it is changed to about 1.2 seconds, and if Tc3 has an initial value of, for example, about 1 second, it is changed to about 0.7 seconds. In other words, Tc1, Tc2, and Tc3 compared with the TTC are values smaller than these initial values.

In step 304, processor 102A calculates the TTC in the same manner as in step 202.

In step 306, the processor 102A determines whether the TTC is equal to or less than the changed Tc1. If the TTC is greater than the changed Tc1, the processor 102A advances the process to step 318.

In step 318, the processor 102A initializes Tc1, Tc2, and Tc3 that were changed in step 302, and ends the process. On the other hand, if in step 306 the TTC becomes equal to or less than the changed Tc1, the processor 102A advances the process to step 308.

In step 308, the processor 102A executes warning control in the same manner as in step 206. Here, the timing of the warning is delayed from the normal timing, i.e., the timing of the warning before Tc1 was changed, because Tc1 has been changed to a value smaller than its initial value. This suppresses the occurrence of a warning.

In step 310, the processor 102A determines whether the TTC is equal to or less than the changed Tc2. If the TTC is greater than the changed Tc2, the processor 102A advances the process to step 318 described above. On the other hand, if the TTC is equal to or less than the changed Tc2, the processor 102A advances the process to step 312.

In step 312, the processor 102A determines whether the TTC is equal to or less than the changed Tc3. If the TTC is equal to or less than the changed Tc3, the processor 102A advances the process to step 314.

In step 314, the processor 102A executes emergency brake control. Here, the timing of emergency brake activation is delayed from the normal activation timing, i.e., the activation timing before Tc3 was changed, because Tc3 has been changed to a value smaller than its initial value. This suppresses the activation of the emergency brake. The processor 102A then proceeds to step 318 described above.

On the other hand, if in step 312, processor 102A determines that TTC is greater than the changed Tc3, it proceeds to step 316.

In step 316, the processor 102A executes warning brake control. Here, the activation timing of the warning brake is delayed from the normal activation timing, i.e., the activation timing before Tc2 was changed, because Tc2 has been changed to a value smaller than its initial value. This suppresses activation of the warning brake, i.e., the issuance of a warning due to activation of the service brake. After that, the processor 102A proceeds to the process of step 318 described above.

In this way, when the suppression flag F is set to 1, the issuance of a warning and the operation of the emergency brake are suppressed. In short, when an object is present in front of the vehicle and the vehicle 1 is approaching an intersection or an ETC gate, the object in front of the vehicle may be a preceding vehicle traveling near the intersection or an opening and closing bar of the ETC gate, and Tc1, Tc2, and Tc3 are each reduced by a first predetermined value. That is, the issuance of a warning and the operation of the emergency brake are suppressed by delaying the timing of the issuance of the warning and the timing of the operation of the emergency brake from the timing of the issuance and the timing of the operation before the change of Tc1, Tc2, and Tc3, respectively. This makes it possible to suppress the operation of the emergency brake and the issuance of a warning, for example, in a situation where it is clear that the preceding vehicle is turning right or left at the intersection or the opening and closing bar of the ETC gate is opening. Therefore, since it is possible to lower the frequency of the operation of the emergency brake and the frequency of the issuance of a warning than the normal frequency, it is possible to suppress excessive operation of the emergency brake and excessive occurrence of warnings for a driver who is aware of the above-mentioned situation. It is also possible to reduce the discomfort felt by the driver by the generation of braking force and warnings due to the application of emergency brakes. Furthermore, it is possible to reduce the wasteful energy consumption associated with unnecessary application of warning brakes and emergency brakes.

Next, a modified example of the regular processing executed by the processor 102A will be described. In this modified example, the object detection unit 104 is a combination of a radar and a monocular camera or a stereo camera, and is capable of recognizing the situation ahead of the vehicle 1. That is, the object detection unit 104 includes an imaging element, such as a monocular camera or a stereo camera, that captures images of the area ahead of the vehicle. The ECU 102 is also configured to acquire the imaging results of the imaging element, and has a function as an image processing device that processes the images captured by the imaging element. Furthermore, the ECU 102 is configured to acquire the judgment results of the ETC on-board unit 112.

When the object detection unit 104 includes an imaging element, the ECU 102 can detect various information related to the situation ahead of the vehicle 1 by processing the image captured by the imaging element. The various information includes lane information such as white and yellow lines that divide the lanes, road structure information such as guardrails and curbs, three-dimensional object information such as the shape, including the width, of an object present ahead of the vehicle 1 and the position of the object in the imaging area of the imaging element, and driving lane information such as the width of the driving lane of the vehicle 1 and the position of the driving lane in the imaging area of the imaging element.

Furthermore, based on the detected three-dimensional object information and driving lane information, the ECU 102 can detect, for example, an object in front that exists within an area defined by the width of the driving lane and that moves in approximately the same direction as the vehicle 1 as a preceding vehicle. However, this is not limited to this, and the ECU 102 may also detect the object as a preceding vehicle based on the shape of the object and other information contained in the detected three-dimensional object information.

Furthermore, when the ECU 102 detects a preceding vehicle, it can detect the lighting status information of the tail lights of the preceding vehicle, such as whether the left and right turn signals installed at the rear of the preceding vehicle are flashing or not, and whether the brake lights are on or not, based on the image captured by the imaging element.

Figure 6 is a flowchart showing a modified example of the scheduled processing. This modified example differs from the scheduled processing of Figure 3 in that steps 30 and 40 are replaced with a new step 80. Therefore, the following description will focus on the processing of step 80, which is different from the scheduled processing of Figure 3. Step 80 is a process for setting the suppression flag F (suppression flag setting process). Figures 7 and 8 are each a flowchart showing a portion of an example of the suppression flag setting process of step 80. In other words, Figures 7 and 8 form a flowchart showing an example of the scheduled processing in its entirety.

In step 502, the processor 102A determines whether the vehicle 1 is approaching an intersection based on the current position of the vehicle 1 on the map. This determination is similar to the determination described in step 30 shown in FIG. 3. If the processor 102A determines that the vehicle 1 is approaching an intersection, the processor 102A advances the process to step 504.

In step 504, processor 102A determines whether the object in front of the vehicle detected in step 10 is a vehicle, i.e., whether a preceding vehicle is present in the driving lane of vehicle 1, based on the three-dimensional object data. If there is no preceding vehicle, the object in front of the vehicle may be, for example, an oncoming vehicle turning right at an intersection, or a pedestrian or bicycle crossing in front of the vehicle at the intersection. Therefore, when processor 102A determines that there is no preceding vehicle, it does not change suppression flag F (F=0) and returns the process to step 50 so that the issuance of a warning and the activation of the emergency brake are not suppressed in such a situation.

On the other hand, in step 504, if processor 102A determines that a preceding vehicle is present in vehicle 1's driving lane, it advances processing to step 506.

In step 506, processor 102A determines whether the left and right turn signals (blinkers) at the rear of the leading vehicle are flashing based on the illumination status information of the taillights of the leading vehicle. When the leading vehicle turns right or left at an intersection, the driver of the leading vehicle generally flashes one of the left or right turn signals and then activates the service brake to slow down the vehicle. Therefore, since the leading vehicle is unlikely to turn right or left when neither the left nor the right turn signals at the rear of the leading vehicle are flashing, it is not desirable to suppress the issuance of a warning and the activation of the emergency brake in such a situation. Therefore, when processor 102A determines that neither the left nor the right turn signals at the rear of the leading vehicle are flashing, it does not change the suppression flag (F=0) and returns the process to step 50.

On the other hand, if one of the left or right turn signals at the rear of the leading vehicle is flashing, the leading vehicle is likely to turn right or left. Therefore, in step 506, if processor 102A determines that one of the left or right turn signals at the rear of the leading vehicle is flashing, it advances the process to step 508.

In step 508, the processor 102A determines whether the preceding vehicle has moved in the direction in which the blinker is flashing. It determines whether the preceding vehicle has started to turn right or left. This determination process will be described with reference to FIG. 9. FIG. 9 shows an image captured by the imaging element, i.e., an image showing the area in front of the vehicle.

Here, for example, if the left turn signal of the preceding vehicle is flashing and the preceding vehicle starts to turn right or left, the projection surface of the preceding vehicle's rear part moves to the left of the vehicle 1's driving lane. Therefore, based on the image captured by the image sensor, more specifically, the processor 102A compares the image in the previous scheduled processing with the image in the current scheduled processing, and determines whether the projection surface of the preceding vehicle's rear part this time has moved in the direction in which the turn signal is flashing more than the projection surface of the preceding vehicle's rear part last time. If it is determined that the projection surface of the preceding vehicle's rear part this time has not moved in the direction in which the turn signal is flashing more than the projection surface of the preceding vehicle's rear part last time, the preceding vehicle has not started to turn right or left. Therefore, when the processor 102A determines that the preceding vehicle is not moving in the direction in which the turn signal is flashing, it does not change the suppression flag F (F=0) and returns the process to step 50 so that the generation of a warning and the activation of the emergency brake are not suppressed in such a situation.

On the other hand, in step 508, if processor 102A determines that the current projection surface of the rear of the preceding vehicle has moved in the direction in which the turn signal is flashing compared to the previous projection surface of the rear of the preceding vehicle, i.e., that the preceding vehicle is moving in the direction in which the turn signal is flashing, it advances the process to step 510.

In step 510, the processor 102A determines whether the preceding vehicle has started to turn right or left. Here, as shown in FIG. 9, the more the preceding vehicle turns right or left, the smaller the ratio of the width (the width Wv of the projection plane present in the driving lane) of the width of the projection plane of the rear of the preceding vehicle that exists within the range that defines the width Wd of the driving lane becomes. Therefore, the processor 102A first calculates the ratio of the width Wv of the projection plane of the rear of the preceding vehicle to the width Wd of the driving lane (hereinafter referred to as "width occupancy Wp (= Wv/Wd)") based on the driving lane information and the three-dimensional object information, more specifically, based on the width Wd of the driving lane of the vehicle 1, the position of the driving lane in the imaging area of the imaging element, and the width Wv of the projection plane of the rear of the preceding vehicle. Then, the processor 102A compares the width occupancy Wp with a predetermined ratio Wt, and when the width occupancy Wp becomes equal to or less than the predetermined ratio Wt, it determines that the preceding vehicle has started to turn right or left. The predetermined percentage Wt is set to, for example, approximately 20%, but is not limited to this and may be set to any value less than approximately 20%.

Here, if one of the left or right turn signals of the preceding vehicle is flashing and the preceding vehicle is moving in the direction in which the turn signals are flashing but Wp is greater than Wt, there is a risk of collision with the preceding vehicle if vehicle 1 continues in its current driving state. In this case, it is desirable to issue a warning and apply the emergency brakes as usual. Therefore, in step 510, if processor 102A determines that Wp is greater than Wt (Wp>Wt), it does not change suppression flag F (F=0) and returns the process to step 50.

On the other hand, in step 510, if Wp is equal to or less than Wt (Wp≦Wt), the processor 102A determines that the preceding vehicle has started to turn right or left, and proceeds to step 512.

In step 512, processor 102A determines whether the brake lights of the preceding vehicle are off based on the detected taillight illumination state information. If the preceding vehicle starts to turn right or left and its brake lights are off, the preceding vehicle will likely begin accelerating to make the turn and will deviate from vehicle 1's driving lane. Therefore, if the brake lights of the preceding vehicle are off, processor 102A determines that the preceding vehicle will deviate from vehicle 1's driving lane, and proceeds to step 514.

In step 514, processor 102A sets inhibition flag F to 1 and returns processing to step 50.

On the other hand, if in step 512, processor 102A determines that the brake lights of the preceding vehicle are on, it proceeds to step 516.

In step 516, the processor 102A determines whether the relative speed Vr of the preceding vehicle with respect to the vehicle 1 is 0 or more. Here, the relative speed Vr of the preceding vehicle with respect to the vehicle 1 is expressed as Vr = V2 - V1, where V1 is the vehicle speed of the vehicle 1 and V2 is the vehicle speed of the preceding vehicle. If Vr is 0 or more, V2 is 0 or more, so that the preceding vehicle will move away from the vehicle 1 even if it is decelerating. Also, since it is determined in step 510 that Wp is 0 or less, it is considered that the preceding vehicle will eventually leave the driving lane even if the vehicle 1 continues its current driving state. An example of such a situation is a situation in which the driver of the preceding vehicle turns the vehicle right or left while applying the service brake. Therefore, if the processor 102A determines that the relative speed Vr is 0 or more, the process proceeds to step 514 and sets the suppression flag F to 1.

That is, when vehicle 1 is approaching an intersection and there is a preceding vehicle in the driving lane of vehicle 1, if the following four conditions are met, it is determined that the preceding vehicle will deviate from the driving lane, and the suppression flag F is set to 1. The first condition is met when one of the left or right turn signals is flashing. The second condition is met when the preceding vehicle is moving in the direction in which the turn signal is flashing. The third condition is met when Wp is equal to or less than Wt. The fourth condition is met when the brake lights of the preceding vehicle are off or the relative speed Vr is equal to or greater than 0. When the suppression flag F is 1, the issuance of a warning and the activation of the emergency brake are suppressed, as will be described in detail below.

If it is determined in step 516 that the relative speed Vr is negative (Vr<0), V1 is greater than V2, and vehicle 1 approaches the preceding vehicle. In this case, the brake lights of the preceding vehicle that has begun to turn right or left are on because the driver of the preceding vehicle has applied the brakes to abort the turn due to the presence of an object in front of the preceding vehicle. Therefore, in order to prevent the issuance of a warning or the application of emergency brakes from being suppressed in such a situation, in step 516, if processor 102A determines that relative speed Vr is less than 0, it does not change suppression flag F (F=0) and returns the process to step 50.

On the other hand, in step 502, if the processor 102A determines that the vehicle 1 is not approaching an intersection, the process proceeds to step 518 shown in FIG. 8.

In step 518, the processor 102A determines whether the vehicle 1 is approaching an ETC gate based on the current position of the vehicle 1 on the map. This determination is similar to the determination described in step 30 shown in FIG. 3. If the processor 102A determines that the vehicle 1 is approaching an ETC gate, the processor 102A advances the process to step 520.

In step 520, processor 102A determines whether the object in front of the vehicle is a vehicle, i.e., whether there is a preceding vehicle, based on the detected three-dimensional object data. If there is a preceding vehicle, and the gate does not open and the preceding vehicle cannot pass through the ETC gate normally, vehicle 1 may collide with the preceding vehicle. Therefore, when processor 102A determines that there is a preceding vehicle (YES), it returns the process to step 50 without changing suppression flag F (F=0) so that the issuance of a warning and the activation of the emergency brake are not suppressed in such a situation.

On the other hand, if vehicle 1 is approaching an ETC gate and there is no preceding vehicle, the object in front of the vehicle is likely to be a barricade. Therefore, in step 520, if processor 102A determines that there is no preceding vehicle (NO), it recognizes that the object in front of the vehicle is a barricade and proceeds to step 522.

However, the process of step 520 is not limited to the process of recognizing that the object in front of the vehicle is a barricade when it is determined that there is no preceding vehicle. For example, depending on the performance of the object detection unit 104 as a stereo camera and the image processing function of the ECU 102, the process of step 520 may be replaced with a process of recognizing a barricade by directly determining whether or not the object in front of the vehicle is a barricade.

In step 522, the processor 102A determines whether the ETC card is valid. For example, the ETC vehicle unit 112 outputs a signal to the ECU 102 indicating that the ETC card is inserted in the insertion section of the ETC vehicle unit 112 and has not expired, i.e., that the ETC card is valid for opening the barrier. When the processor 102A receives the above-mentioned signal from the ETC vehicle unit 112, it determines that the ETC card is valid. If the ETC card is not inserted or the ETC card is not valid for opening the barrier because it has expired, the barrier will not open, and there is a risk that the vehicle 1 will collide with the barrier if the current driving state is continued. Therefore, when the ETC vehicle unit 112 determines that the ETC card is not valid, the processor 102A does not change the suppression flag F (F=0) and returns the process to step 50 so that the generation of a warning and the activation of the emergency brake are not suppressed in such a situation.

On the other hand, in step 522, when the ETC in-vehicle unit 112 determines that the ETC card is valid, the processor 102A advances the process to step 514. That is, when the vehicle 1 is approaching an ETC gate, if the object in front of the vehicle is recognized as a gate barrier, and the ETC in-vehicle unit 112 determines that the ETC card is valid for opening the gate barrier, the inhibition flag F is set to 1. The processor 102A then returns the process to step 50.

Also, in step 518, if the processor 102A determines that the vehicle 1 is not approaching an ETC gate, the process proceeds to step 504. In other words, if the vehicle 1 is not approaching either an intersection or an ETC gate, the process from step 504 onwards is executed, and the inhibition flag F is set to 1 or 0.

Here, if the vehicle 1 is not approaching either an intersection or an ETC gate, and step 512 or 516 is judged as YES, the process proceeds to step 514, where the suppression flag F is set to 1. For example, when the vehicle 1 and the preceding vehicle are traveling on a road adjacent to a parking lot of a specified store or on a road where lane changing is possible, the driver of the preceding vehicle may turn on one of the left and right turn signals and turn the vehicle to the right or left to enter the parking lot of the store or to change lanes. That is, even if the vehicle 1 is not approaching either an intersection or an ETC gate, when all of the first, second, third, and fourth conditions are satisfied, it is judged that the preceding vehicle will deviate from the driving lane of the vehicle 1 by turning to the right or left or changing lanes, and the suppression flag F is set to 1. Note that the case where the suppression flag F is not changed is the same as that described in steps 504, 506, 508, 510, 512, and 516, and the description will be omitted.

After that, the processor 102A selectively executes the normal control process or the suppression control process according to the suppression flag F set by the suppression flag setting process of step 80. Hereinafter, the action and effect when the suppression flag F is set to 1 by the modified fixed-time process will be described. That is, when the vehicle 1 is approaching an intersection, and it is determined based on the imaging result of the imaging element that a preceding vehicle exists in the driving lane of the vehicle 1 and that the preceding vehicle will deviate from the driving lane, the generation of the warning and the operation of the emergency brake are suppressed by delaying the timing of the warning and the operation of the emergency brake by changing various threshold values. The same is true when the vehicle 1 is approaching an ETC gate, and the object in front of the vehicle is recognized as a gate bar based on the imaging result of the imaging element, and the ETC on-board unit 112 determines that the ETC card is valid. As a result, it is possible to lower the frequency of emergency brake operation and the frequency of warning occurrence below the normal frequency, as in the case described with reference to FIG. 5. This makes it possible to prevent excessive emergency braking and excessive warnings for drivers who are aware of situations in which it is clear that the vehicle ahead is about to turn right or left at an intersection, or that the bars at an ETC gate are about to open.

In addition, in a modified fixed-time processing, the suppression flag F is set to 1 when various conditions are met, thereby making the ECU 102 also recognize the above-mentioned situation recognized by the driver. This makes it possible to align the control of the ECU 102 with the intention of the driver who considers it unnecessary to perform braking operations that generate relatively strong braking forces or to issue warnings. Therefore, it is possible to further reduce the discomfort felt by the driver due to the issuance of warnings or the application of emergency brakes. Furthermore, it is possible to suppress wasteful energy consumption associated with unnecessary operation of warning brakes or emergency brakes.

Furthermore, when the vehicle 1 is not approaching either an intersection or an ETC gate and there is a preceding vehicle in the driving lane of the vehicle 1, if all of the first, second, third and fourth conditions are satisfied, the suppression flag F is set to 1. That is, even if there is a preceding vehicle but the vehicle 1 is not approaching either an intersection or an ETC gate, when it is determined that the preceding vehicle will deviate from the driving lane of the vehicle 1 by turning right or left or changing lanes, the generation of a warning and the operation of the emergency brake are suppressed. For example, a driver who recognizes a situation in which it is clear that the preceding vehicle will turn right or left or change lanes in a place other than near an intersection or an ETC may think that the possibility of a collision with the preceding vehicle is low and that it is not necessary to operate the service brake. Therefore, in this case as well, excessive operation of the emergency brake and excessive generation of warnings for the driver can be suppressed. As a result, it is possible to reduce the discomfort given to the driver and to suppress wasteful energy consumption associated with unnecessary operation of the warning brake and the emergency brake.

Next, a first modified example of the suppression control process will be described with reference to FIG. 10. As shown in FIG. 10, the first modified example of the suppression control process differs from the suppression control process described with reference to FIG. 5 in that steps 302 and 318 are replaced with new steps 320 and 322, respectively, and steps 306, 308, 310, and 316 are omitted. The following description will focus on the differences.

In step 320, the processor 102A changes the second deceleration. More specifically, the processor 102A changes the second deceleration in the emergency brake control by subtracting a second predetermined value from its initial value. The second predetermined value is, for example, a value for reducing the second deceleration so that the changed second deceleration becomes equal to the initial value of the first deceleration in the warning brake control. For example, if the initial value of the first deceleration is about 0.2 G and the initial value of the second deceleration is about 0.5 G, the third predetermined value is about 0.3 G.

After that, when the processor 102A calculates the TTC in step 304, the process proceeds to step 312, where it is determined whether the TTC has become equal to or less than Tc3. That is, in the first modified example, the TTC is not compared with Tc1, which specifies the timing of the execution of the warning control, and with Tc2, which specifies the timing of the execution of the warning brake control (the processes of steps 306 and 310 shown in FIG. 5 are omitted). In addition, the process of executing the warning control (the process of step 308 shown in FIG. 5) and the process of executing the warning brake control (the process of step 316 shown in FIG. 5) are omitted. That is, in the first modified example of the suppression control process, the occurrence of a warning is suppressed by prohibiting the execution of the warning control and the warning brake control.

After that, when the processor 102A determines in step 312 that the TTC has become equal to or less than Tc3, the processor 102A advances the process to step 314 and executes emergency brake control. Here, the second deceleration has been changed to a deceleration smaller than its initial value. Therefore, the processor 102A outputs a brake activation signal including information indicating the changed second deceleration to the brake ECU 100. As a result, the emergency brake is activated so as to brake and stop the vehicle 1 at a deceleration smaller than the deceleration during normal emergency brake control. In other words, the activation of the emergency brake is suppressed. The processor 102A then advances the process to step 322. In step 322, the processor 102A initializes the second deceleration changed in step 320, and ends the process.

On the other hand, if the processor 102A determines in step 312 that the TTC is greater than Tc3, the processor 102A does not execute emergency brake control (skips step 314) and proceeds to step 322 described above. The processor 102A then initializes the second deceleration changed in step 320 and ends the process.

In the first modified example of the suppression control process described above, when the vehicle 1 is approaching an intersection, and it is determined based on the imaging result of the imaging element that a preceding vehicle is in the driving lane of the vehicle 1 and that the preceding vehicle will deviate from the driving lane, the execution of the warning control and the warning brake control is prohibited and the operation of the emergency brake is suppressed. The same is true when the vehicle 1 is approaching an ETC gate, and the object in front of the vehicle is recognized as a gate based on the imaging result of the imaging element, and the ETC onboard unit 112 determines that the ETC card is effective for opening the gate. Here, the operation of the emergency brake is suppressed by reducing the second deceleration by a second predetermined value to reduce the braking force during the emergency brake operation compared to normal operation. As a result, even if the emergency brake is operated, the braking force is reduced, so that the generation of excessive braking force is suppressed for a driver who is aware of a situation in which it is clear that the preceding vehicle will turn right or left at the intersection or that the gate gate gate will open, and the emergency brake can be suppressed from being operated excessively. In addition, it is possible to have the ECU 102 recognize the above-mentioned situation, prohibit the issuance of a warning, and suppress the operation of the emergency brake. In other words, it is possible to align the control of the ECU 102 with the intention of the driver who is aware of the above-mentioned situation and does not want a braking operation that generates a relatively strong braking force or the issuance of a warning, so that the discomfort felt by the driver due to the issuance of a warning or the operation of the emergency brake can be further reduced. Furthermore, it is possible to suppress the wasteful energy consumption associated with unnecessary operation of the warning brake or the emergency brake.

Furthermore, when the vehicle 1 is not approaching either an intersection or an ETC gate and there is a preceding vehicle, and all of the first to fourth conditions are satisfied, the suppression flag F is set to 1. That is, even if the vehicle 1 is not approaching either an intersection or an ETC gate, when a preceding vehicle is present in the driving lane of the vehicle 1 and it is determined that the preceding vehicle will deviate from the driving lane, the execution of the warning control and the warning brake control is prohibited and the operation of the emergency brake is suppressed. For example, a driver who recognizes a situation in which it is clear that the preceding vehicle will turn right or left or change lanes at a place other than an intersection or an ETC may think that the possibility of a collision with the preceding vehicle is low and that it is not necessary to operate the service brake. Therefore, in this case as well, it is possible to suppress the excessive operation of the emergency brake for the driver while prohibiting the issuance of a warning, thereby reducing the discomfort given to the driver. In addition, the braking force generated by the operation of the emergency brake is suppressed, so that unnecessary energy consumption can be suppressed.

In the first modified example of the suppression control process described above, the execution of the warning control and the warning brake control is prohibited, and the second deceleration is changed to prohibit the issuance of a warning and suppress the operation of the emergency brake, but this is not limited to this. For example, as in the second modified example of the suppression control process shown in FIG. 11, only steps 306 and 308 shown in FIG. 5 may be omitted, and the process of step 302 may be replaced with a new process of step 324 that changes the first deceleration in the warning brake control in addition to the second deceleration, and the process of step 318 may be replaced with a new process of step 326 that initializes the first deceleration and the second deceleration changed in step 324. In the second modified example, the first deceleration is changed, for example, by subtracting a third predetermined value from its initial value. As a result, when the TTC is equal to or less than Tc2 but greater than Tc3, that is, when the process proceeds to step 316, the warning brake is operated so as to brake the vehicle 1 at a deceleration smaller than the deceleration during the execution of the normal warning brake control, thereby suppressing the operation of the warning brake. The third predetermined value is a value for reducing the first deceleration so that the changed first deceleration becomes, for example, the deceleration when engine braking is activated. For example, if the initial value of the first deceleration is about 0.2 G and the deceleration when engine braking is activated is about 0.03 G, the second predetermined value is about 0.17 G. However, this is not limited to this, and the second predetermined value may be a value determined by a table obtained in advance, for example, through experiments, so that the deceleration is at a level that the driver does not feel uncomfortable when the warning brake is activated depending on the vehicle speed, the distance to an object in front of the vehicle, or the relative speed to the object.

In addition, in the suppression control process described with reference to Figures 5, 10, and 11 in the modified example of the fixed-time process, the issuance of a warning and the activation of the emergency brake are suppressed based on signals from the object detection unit 104 or the image sensor and current position acquisition unit 106 constituting part of the object detection unit 104, but this is not limited to this. For example, the processor 102A may reduce each of the threshold values Tc1, Tc2, and Tc3, reduce each deceleration, or prohibit the output of a signal to the notification unit 114 as the vehicle speed decreases, based on a signal output from the vehicle speed detection unit 108 in addition to the signals from the image sensor and current position acquisition unit 106.

In the above description, in the suppression control process described with reference to FIG. 5, Tc1, Tc2, and Tc3 are changed to suppress the issuance of a warning and the operation of the emergency brake. In the first modified example of the suppression control process described with reference to FIG. 10, the execution of the warning control and the warning brake control is prohibited, and the second deceleration is changed to suppress the operation of the emergency brake. In the second modified example of the suppression control process described with reference to FIG. 11, the execution of the warning control is prohibited, and the first deceleration and the second deceleration are changed to suppress the operation of the warning brake and the emergency brake. However, this is not limited to these, and for example, the issuance of a warning by the warning control and the warning brake control may be suppressed by changing Tc1 and Tc2, and the operation of the emergency brake may be suppressed by changing the second deceleration. In addition, for example, the execution of the warning control and the warning brake control may be prohibited, and the operation of the emergency brake may be suppressed by combining the change in Tc3 and the change in the second deceleration. In this way, by appropriately combining the prohibition of execution of warning control or warning brake control, the change of various thresholds, and the change of various deceleration rates, it is possible to create suppression control processing that is not listed in this specification.

In addition, in the above description, the second deceleration in the emergency brake control is a predetermined value, but this is not limited to this. For example, the ECU 102 may be configured to calculate the required deceleration required to suppress a collision and collision damage as the second deceleration based on the distance D, the relative speed Vr, the vehicle speed, and the braking performance of the vehicle 1, and output a brake actuation signal including information indicating the calculated required deceleration to the brake ECU 100.

Furthermore, in the above description, the ECU 102 is configured to sequentially execute warning control and control that combines execution of warning control and execution of warning brake control in accordance with the TTC in the normal control process in order to notify the driver that a collision is highly likely. However, this is not limited to this, and for example, warning control may not be executed even if the TTC is equal to or less than Tc1, and only warning brake control may be executed when the TTC is equal to or less than Tc2 and greater than Tc3. Also, the driver may be notified that a collision is highly likely by only executing warning control without executing warning brake control. In other words, the ECU 102 may be configured to notify the driver that a collision is highly likely by executing at least one of warning control and warning brake control in accordance with the TTC.

Furthermore, a person skilled in the art will easily understand that new embodiments can be created by omitting parts of the technical ideas of the various embodiments described above, combining parts of them as appropriate, or substituting parts of them.

1 Vehicle 100 Brake control device (Brake ECU)
102 Electronic control unit (ECU)
102A Processor 102D Input/Output Circuit 104 Object Detection Unit 106 Current Position Acquisition Unit 112 ETC Vehicle Unit 114 Notification Unit

Claims (4)

An electronic control device that activates a collision damage mitigation brake when a collision time until a collision with an object located in front of a vehicle becomes equal to or less than a predetermined threshold,
an electronic control device that acquires current position information of the vehicle and surrounding environment information including map information, and when it determines that the vehicle is approaching an intersection based on the vehicle's current position on the map, suppresses operation of the collision damage mitigation brake when all of the following conditions are satisfied based on the image capture result of an image capture element that captures an image in front of the vehicle: a first condition that a preceding vehicle is present in the vehicle's driving lane and one of the left or right turn indicators provided at the rear of the preceding vehicle is flashing; a second condition that the preceding vehicle is moving in the direction in which the turn indicator is flashing; a third condition that the ratio of the width of the projection surface of the rear of the preceding vehicle to the width of the driving lane is equal to or less than a predetermined ratio; and a fourth condition that the brake lights provided at the rear of the preceding vehicle are extinguished or the relative speed of the preceding vehicle to the vehicle is zero or greater . 2. The electronic control device according to claim 1, wherein when it is determined that the vehicle is approaching an ETC gate based on the vehicle's current position on a map, the electronic control device recognizes that the object is a starting control rod provided at the ETC gate based on the image capture result of an imaging element that captures an image in front of the vehicle, and when it is determined by an ETC onboard unit that the ETC card is valid, the electronic control device suppresses operation of the collision damage mitigation brake. The collision damage mitigation brake operates to brake the vehicle at a predetermined deceleration,
3. The electronic control device according to claim 1 , wherein the operation of the collision damage mitigation brake is suppressed by reducing the predetermined threshold by a first predetermined value or by reducing the predetermined deceleration by a second predetermined value. 4. The electronic control device according to claim 1, wherein when a service brake is applied by a driver, the electronic control device forcibly ends inhibition of the operation of the collision damage mitigation brake.