Deceleration Detection Device

Abstract

To precisely detect speed reduction of a preceding vehicle without any influence of bad weather.SOLUTION: A speed reduction detection device 50 comprises: a body detector 1a which detects a body in a circumference of the vehicle; a rainfall detector 1b which detects a rainfall state in the circumference of the vehicle; a lightness detector 1c which detects lightness in the circumference of the vehicle; and a speed reduction determination part 145 which detects whether a preceding vehicle reduces the speed based upon a quantity of variation in vehicle speed of the preceding vehicle traveling before the vehicle that the body detector 1a detects, a lighting state of brake lamps of the preceding vehicle that the body detector 1a detects, the rainfall state that the rainfall detector 1b detects, and the lightness that the lightness detector 1c detects.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a deceleration detection device for detecting the deceleration of a forward vehicle. [Background technology]

[0002] Conventionally, there has been known an apparatus that recognizes a vehicle traveling ahead of a host vehicle by sensor fusion using a radar and a camera, and controls an automatic braking system in accordance with the recognition result (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-329779 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, due to the influence of weather, external light, and the like, it may be difficult to accurately detect the deceleration of the vehicle ahead even with sensor fusion. [Means for solving the problem]

[0005] A deceleration detection device according to one aspect of the present invention includes an object detection unit that detects objects around the host vehicle, a rainfall detection unit that detects the rainfall conditions around the host vehicle, a brightness detection unit that detects the brightness around the host vehicle, and a deceleration determination unit that determines whether or not the vehicle in front is decelerating based on the amount of change in vehicle speed of a vehicle traveling in front of the host vehicle detected by the object detection unit, the state of the brake lights of the vehicle in front detected by the object detection unit, the rainfall conditions detected by the rainfall detection unit, and the brightness detected by the brightness detection unit. The deceleration determination unit determines that the vehicle in front has decelerated when the change in speed of the vehicle in front becomes equal to or greater than a threshold value that is set according to brightness, rainfall conditions, and the state of the brake lights. The threshold value is set to a first threshold value when rain is not detected by the rainfall detection unit and the object detection unit does not detect that the brake lights are on, set to a second threshold value smaller than the first threshold value when rain is detected by the rainfall detection unit and the object detection unit does not detect that the brake lights are on, and set to a third threshold value smaller than the second threshold value when rain is detected by the rainfall detection unit and the object detection unit detects that the brake lights are on. Effect of the Invention

[0006] According to the present invention, the deceleration of a forward vehicle can be detected with high accuracy even in bad weather or the like. [Brief description of the drawings]

[0007] [Figure 1] 1 is a block diagram showing an overall configuration of a vehicle control system having a deceleration detection device according to an embodiment of the present invention; [Diagram 2] 1 is a diagram showing an example of a driving scene of a host vehicle having a deceleration detection device according to an embodiment of the present invention; [Diagram 3] 1 is a block diagram showing a configuration of a main part of a deceleration detection device according to an embodiment of the present invention; [Figure 4] 5 is a diagram showing the relationship between a threshold value for determining deceleration used in the deceleration detection device according to the embodiment of the present invention and brightness, rainfall amount, and a brake lamp illumination state. FIG. [Diagram 5] 4 is a flowchart showing an example of processing executed by the controller of FIG. 3; [Figure 6A] 5A to 5C are diagrams showing an example of an operation of the deceleration detection device according to the embodiment of the present invention. [Figure 6B] 6A to 6C are diagrams showing another example of the operation of the deceleration detection device according to the embodiment of the present invention. [Figure 6C] 10A to 10C are diagrams showing still another example of the operation of the deceleration detection device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to Figs. 1 to 6C. A deceleration detection device according to an embodiment of the present invention can be applied to both vehicles having an automatic driving function, i.e., an automatic driving vehicle, and a manually driven vehicle not having an automatic driving function. Below, an example in which the deceleration detection device is applied to an automatic driving vehicle will be described. Note that the vehicle to which the deceleration detection device according to this embodiment is applied may be referred to as the subject vehicle to distinguish it from other vehicles.

[0009] The host vehicle may be an engine vehicle having an internal combustion engine (engine) as a drive source, an electric vehicle having a drive motor as a drive source, or a hybrid vehicle having an engine and a drive motor as drive sources. The host vehicle (autonomous vehicle) can run not only in an autonomous driving mode in which no driving operation by the driver is required, but also in a manual driving mode in which the driver operates the vehicle.

[0010] First, a schematic configuration related to the automatic driving will be described. Fig. 1 is a block diagram showing a schematic overall configuration of a vehicle control system 100 having a deceleration detection device according to an embodiment of the present invention. As shown in Fig. 1, the vehicle control system 100 mainly includes a controller 10, an external sensor group 1 communicably connected to the controller 10 via a CAN communication line or the like, an internal sensor group 2, an input / output device 3, a positioning unit 4, a map database 5, a navigation device 6, a communication unit 7, and an actuator AC for driving.

[0011] The external sensor group 1 is a collective term for a plurality of sensors (external sensors) that detect the external situation, which is information about the surroundings of the vehicle. For example, the external sensor group 1 includes a lidar that detects the positions (distance and direction from the vehicle) of objects around the vehicle by emitting laser light and detecting reflected light, a radar that detects the positions of objects around the vehicle by emitting electromagnetic waves and detecting reflected waves, and a camera that captures images of the surroundings of the vehicle.

[0012] The internal sensor group 2 is a collective term for a plurality of sensors (internal sensors) that detect the driving state of the vehicle. For example, the internal sensor group 2 includes a vehicle speed sensor that detects the vehicle speed of the vehicle, an acceleration sensor that detects the acceleration in the forward / rearward and left / right directions of the vehicle, a rotation speed sensor that detects the rotation speed of the driving source, etc. The internal sensor group 2 also includes sensors that detect the driving operations of the driver in the manual driving mode, such as the operation of the accelerator pedal, the operation of the brake pedal, the operation of the steering wheel, etc.

[0013] The input / output device 3 is a general term for devices that input commands from the driver and output information to the driver. For example, the input / output device 3 includes various switches through which the driver inputs various commands by operating an operating member, a microphone through which the driver inputs commands by voice, a display that provides information to the driver through a displayed image, a speaker that provides information to the driver by voice, etc. The various switches include a manual / automatic changeover switch that commands either the automatic driving mode or the manual driving mode.

[0014] The positioning unit (GNSS unit) 4 has a positioning sensor that receives positioning signals transmitted from positioning satellites. The positioning satellites are artificial satellites such as GPS satellites and quasi-zenith satellites. The positioning unit 4 measures the current position (latitude, longitude, altitude) of the vehicle using the positioning information received by the positioning sensor.

[0015] The map database 5 is a device that stores general map information used in the navigation device 6, and is configured with, for example, a hard disk or a semiconductor element. The map information includes road position information, road shape (curvature, etc.) information, and intersection and branch point position information. Note that the map information stored in the map database 5 is different from the highly accurate map information stored in the storage unit 12 of the controller 10.

[0016] The navigation device 6 is a device that searches for a target route on roads to a destination input by the driver and provides guidance along the target route. The input of the destination and guidance along the target route are performed via the input / output device 3. The target route is calculated based on the current position of the vehicle measured by the positioning unit 4 and map information stored in the map database 5. The current position of the vehicle can also be measured using detection values ​​of the external sensor group 1, and the target route may be calculated based on this current position and highly accurate map information stored in the memory unit 12.

[0017] The communication unit 7 communicates with various servers (not shown) via networks including wireless communication networks such as the Internet and mobile phone networks, and acquires map information, driving history information, traffic information, and the like from the servers periodically or at any timing. In addition to acquiring driving history information, the driving history information of the vehicle may be transmitted to the server via the communication unit 7. Networks include not only public wireless communication networks, but also closed communication networks provided for each predetermined management area, such as wireless LAN, Wi-Fi (registered trademark), Bluetooth (registered trademark), and the like. The acquired map information is output to the map database 5 and the storage unit 12, and the map information is updated.

[0018] Actuator AC is a driving actuator for controlling the driving of host vehicle 101. When the driving source for driving is an engine, actuator AC includes a throttle actuator for adjusting the opening of a throttle valve (throttle opening) of the engine. When the driving source for driving is a driving motor, actuator AC includes the driving motor. Actuator AC also includes a brake actuator for operating the braking device of the host vehicle and a steering actuator for driving the steering device.

[0019] The controller 10 is composed of an electronic control unit (ECU). More specifically, the controller 10 includes a computer having an arithmetic unit 11 such as a CPU (microprocessor), a storage unit 12 such as a ROM, a RAM, and other peripheral circuits (not shown) such as an I / O interface. Note that although a plurality of ECUs with different functions, such as an engine control ECU, a travel motor control ECU, and a braking device ECU, can be provided separately, the controller 10 is shown in FIG. 1 as a collection of these ECUs for the sake of convenience.

[0020] High-precision road map information is stored in the memory unit 12. This road map information includes road position information, road shape (curvature, etc.) information, road gradient information, intersection and branch point position information, number of lanes information, lane width and position information for each lane (information on lane center position and lane position boundary line), position information of landmarks (traffic lights, signs, buildings, etc.) as markers on the map, and road surface profile information such as road surface unevenness. The map information stored in the memory unit 12 includes map information acquired from outside the vehicle via the communication unit 7, and map information created by the vehicle itself using detection values ​​of the external sensor group 1 or detection values ​​of the external sensor group 1 and the internal sensor group 2.

[0021] The calculation unit 11 has, as its functional configuration, a vehicle position recognition unit 13, an external environment recognition unit 14, a behavior plan generation unit 15, and a driving control unit 16.

[0022] The vehicle position recognition unit 13 recognizes the position of the vehicle on the map (the vehicle position) based on the vehicle position information obtained by the positioning unit 4 and the map information in the map database 5. The vehicle position may be recognized using the map information stored in the storage unit 12 and the surrounding information of the vehicle detected by the external sensor group 1, thereby making it possible to recognize the vehicle position with high accuracy. When the vehicle position can be measured by a sensor installed externally on or beside the road, the vehicle position can also be recognized by communicating with the sensor via the communication unit 7.

[0023] The external environment recognition unit 14 recognizes the external situation around the vehicle based on signals from the external sensor group 1, such as a lidar, radar, and camera. For example, it recognizes the positions, speeds, and accelerations of surrounding vehicles (vehicles ahead and vehicles behind) traveling around the vehicle, the positions of surrounding vehicles stopped or parked around the vehicle, and the positions and states of other objects. Examples of other objects include signs, traffic lights, markings such as road dividing lines and stop lines, buildings, guardrails, utility poles, signs, pedestrians, bicycles, and the like. Examples of the states of other objects include the colors of traffic lights (red, green, yellow), and the moving speeds and directions of pedestrians and bicycles.

[0024] The action plan generating unit 15 generates a running trajectory (target trajectory) of the vehicle from the current time to a predetermined time ahead based on, for example, the target route calculated by the navigation device 6, the map information stored in the storage unit 12, the vehicle position recognized by the vehicle position recognition unit 13, and the external situation recognized by the external environment recognition unit 14. When there are multiple trajectories that are candidates for the target trajectory on the target route, the action plan generating unit 15 selects an optimal trajectory that satisfies criteria such as complying with laws and regulations and traveling efficiently and safely, and sets the selected trajectory as the target trajectory. Then, the action plan generating unit 15 generates an action plan according to the generated target trajectory. The action plan generating unit 15 generates various action plans corresponding to overtaking driving to overtake a preceding vehicle, lane changing driving to change the traveling lane, following driving to follow a preceding vehicle, lane keeping driving to maintain the lane so as not to deviate from the traveling lane, decelerating driving or accelerating driving, etc. When generating the target trajectory, the action plan generating unit 15 first determines a driving mode, and generates the target trajectory based on the driving mode.

[0025] In the autonomous driving mode, the driving control unit 16 controls each actuator AC so that the vehicle travels along the target trajectory generated by the behavior plan generating unit 15. More specifically, the driving control unit 16 calculates a required driving force for obtaining the target acceleration per unit time calculated by the behavior plan generating unit 15, taking into consideration the driving resistance determined by the road gradient in the autonomous driving mode. Then, for example, the driving control unit 16 feedback-controls the actuators AC so that the actual acceleration detected by the internal sensor group 2 becomes the target acceleration. That is, the driving control unit 16 controls the actuators AC so that the vehicle travels at the target vehicle speed and the target acceleration. In the manual driving mode, the driving control unit 16 controls each actuator AC in response to a driving command (such as a steering operation) from the driver acquired by the internal sensor group 2.

[0026] 2 shows an example in which the host vehicle 101 travels at a vehicle speed V1 while following a leading vehicle 102 traveling ahead of the host vehicle 101. During following travel, the vehicle speed V2 of the leading vehicle 102 is calculated based on signals from the external sensor group 1, and deceleration of the leading vehicle 102 is detected based on a change amount ΔV in the vehicle speed V2.

[0027] Incidentally, the detection accuracy of the external sensor group 1, such as a radar, a lidar, and a camera, may be affected by weather conditions and light outside the vehicle. For example, when there is an extremely heavy amount of rainfall, such as a torrential downpour, the rain causes light scattering, which affects the detection accuracy of the lidar, and also affects the detection accuracy of the radar. In this case, it also affects edge detection by the camera. In addition, when there is a strong light source, such as strong sunlight, it affects edge detection by the camera, and the detection accuracy of the camera is also affected when there is backlighting or when the surroundings are dark, such as at night.

[0028] When the vehicle is affected by weather and brightness in this way, the accuracy of the detection values ​​of the external sensor group 1 detected at a predetermined interval decreases, and the position of the vehicle 102 ahead recognized based on the detection values ​​temporarily becomes different from the actual position. backward (area A1 in Figure 2), or forward In other words, there is a risk of a momentary jump occurring in the coordinates of the detected value. As a result, the measurement accuracy of the deceleration or speed change of the forward vehicle 102 may be reduced. Decline Therefore, in order to accurately detect the speed change, particularly the deceleration, of the leading vehicle 102 without being affected by the weather or brightness, the deceleration detection device of this embodiment is configured as follows.

[0029] Fig. 3 is a block diagram showing a configuration of a main part of a deceleration detection device 50 according to an embodiment of the present invention. The deceleration detection device 50 constitutes a part of the vehicle control system 100 of Fig. 1. As shown in Fig. 3, the deceleration detection device 50 has an object detector 1a, a rainfall detector 1b, a brightness detector 1c, a vehicle speed sensor 2a, and an actuator AC.

[0030] The object detector 1a is a monocular camera having an imaging element (image sensor) such as a CCD or CMOS, and constitutes a part of the external sensor group 1 in FIG. 1. The camera may be a stereo camera. The camera is attached, for example, to a predetermined position in front of the host vehicle 101, and continuously captures images of the space in front of the host vehicle 101 to obtain images of objects (camera images). The objects include a vehicle 102 ahead, and an image of the brake lights on the rear of the vehicle 102 ahead is obtained. In addition to the camera, the object detector 1a includes either a radar or a lidar, or both. That is, it includes a distance detector that detects the distance between the host vehicle 101 and the object (vehicle 102 ahead).

[0031] The rainfall detector 1b is a detector that detects the presence or absence of raindrops and the amount of raindrops (rainfall amount), and can be configured with a raindrop sensor. The raindrop sensor is attached, for example, to the outside of the windshield. A wiper sensor that detects the movement of the wiper may be provided to detect (estimate) the amount of rainfall. The brightness detector 1c is a detector that detects the brightness (illuminance) of the surroundings, and can be configured with an illuminance sensor. The illuminance sensor is attached, for example, to the inside of the windshield. The rainfall detector 1b and the brightness detector also constitute a part of the external sensor group 1 in FIG. 1. The vehicle speed sensor 2a detects the vehicle speed of the host vehicle 101. The vehicle speed sensor 2a constitutes a part of the internal sensor group 2 in FIG. 1.

[0032] The controller 10 has, as functional components carried out by the calculation unit 11 (FIG. 1), a vehicle recognition unit 141, a vehicle speed calculation unit 142, a lamp illumination determination unit 143, a threshold determination unit 144, and a deceleration determination unit 145 in addition to the driving control unit 16. The vehicle recognition unit 141, the vehicle speed calculation unit 142, the lamp illumination determination unit 143, the threshold determination unit 144, and the deceleration determination unit 145 are provided to detect the driving conditions of the forward vehicle 102, and are configured by, for example, the external environment recognition unit 14 in FIG. 1.

[0033] The vehicle recognition unit 141 recognizes the presence or absence of a preceding vehicle 102 based on a signal from the object detector 1a. For example, the vehicle recognition unit 141 recognizes the preceding vehicle 102 when the vehicle 101 follows the preceding vehicle 102 at a predetermined distance. The distance between the recognized preceding vehicle 102 and the host vehicle 101 is detected by the object detector 1a (distance detector).

[0034] The vehicle speed calculation unit 142 calculates a relative vehicle speed Vα (=V1-V2) between the vehicle speed V1 of the host vehicle 101 and the vehicle speed V2 of the forward vehicle 102 by time-differentiating the inter-vehicle distance detected by the object detector 1a. The vehicle speed V1 of the host vehicle 101 detected by the vehicle speed sensor 2a is added to this relative vehicle speed Vα to calculate the vehicle speed V2 of the forward vehicle 102.

[0035] The lamp illumination determination unit 143 determines whether or not the brake lights on the rear of the forward vehicle 102 are illuminated, based on a signal from the object detector 1a. Whether or not the brake lights are illuminated can be determined by determining whether or not a red area having a luminance equal to or greater than a predetermined value is detected in front of the host vehicle 101. Therefore, even when there is heavy rainfall or the brightness of the outside world is equal to or greater than a predetermined value, the lamp illumination determination unit 143 can easily and accurately determine whether or not the brake lights are illuminated.

[0036] The threshold value determination unit 144 determines a threshold value for determining whether or not the forward vehicle 102 is decelerating. More specifically, one of the multiple threshold values ​​ΔVa stored in advance in the storage unit 12 is selected based on the amount of rainfall detected by the rainfall detector 1b, the brightness detected by the brightness detector 1c, and the lighting state of the brake lamps determined by the lamp lighting determination unit 143.

[0037] FIG. 4 is a diagram showing the relationship between brightness, rainfall amount, brake lamp illumination state, and threshold value ΔVa. In FIG. 4, brightness is divided into two stages, day and night. That is, when brightness lx (illuminance) is equal to or greater than a predetermined value lx1, it is day, and when it is less than the predetermined value lx1, it is night. Rainfall amount is divided into four stages, zero, light rain, strong rain, and heavy rain. That is, when rainfall amount R is greater than 0 and less than a predetermined value R1, it is light rain, when it is equal to or greater than the predetermined value R1 and less than a predetermined value R2 (>R1), it is heavy rain, and when it is equal to or greater than the predetermined value R2, it is heavy rain. The amount of rainfall corresponds to the wiper operation amount (zero, intermittent, low, high). Therefore, the threshold value ΔVa may be determined using the wiper operation amount instead of the amount of rainfall. The brake lamp illumination state is divided into two stages, off and on.

[0038] The threshold value determination unit 144 determines the threshold value ΔVa to be one of ΔVa0 to ΔVa5 using the relationship in FIG. 4. The threshold value ΔVa is an absolute value, and has the relationship ΔVa0>ΔVa1>ΔVa2>ΔVa3>ΔVa4>ΔVa5. Specifically, when the brightness is daytime and the amount of rainfall is zero, the threshold value determination unit 144 determines the threshold value to ΔVa0 in both cases of the brake lamp being turned on and off. When the amount of rainfall is light, if the brake lamp is turned off, the threshold value is determined to be ΔVa0, and if the brake lamp is turned on, the threshold value is determined to be ΔVa1. When the amount of rainfall is heavy, if the brake lamp is turned off, the threshold value is determined to be ΔVa1, and if the brake lamp is turned on, the threshold value is determined to be ΔVa2. When the amount of rainfall is heavy, if the brake lamp is turned off, the threshold value is determined to be ΔVa2, and if the brake lamp is turned on, the threshold value is determined to be ΔVa3.

[0039] On the other hand, when the brightness is night and the amount of rainfall is zero, the threshold value determination unit 144 determines the threshold value to ΔVa0 in both cases of the brake lamps being turned on and off. When the amount of rainfall is light, if the brake lamps are turned off, the threshold value is determined to ΔVa1, and if the brake lamps are turned on, the threshold value is determined to ΔVa2. When the amount of rainfall is heavy, if the brake lamps are turned off, the threshold value is determined to ΔVa2, and if the brake lamps are turned on, the threshold value is determined to ΔVa3. When the amount of rainfall is heavy, if the brake lamps are turned off, the threshold value is determined to ΔVa4, and if the brake lamps are turned on, the threshold value is determined to ΔVa5. In this way, the darker the brightness is and the greater the amount of rainfall is, the smaller the threshold value ΔVa is determined to be. Also, except when the amount of rainfall is zero, if the brake lamps are turned on, the threshold value ΔVa is determined to be smaller than when the brake lamps are turned off.

[0040] The threshold value ΔVa is not uniquely determined according to the brightness, the amount of rainfall, and the lighting state of the brake lights, but is determined according to the vehicle speed V1 of the vehicle 101 and the distance between the vehicle and the vehicle ahead, etc. As an example, the threshold value ΔVa0 is about 2 to 3 m / s.

[0041] The deceleration determination unit 145 calculates a change amount ΔV per unit time of the vehicle speed V2 of the forward vehicle 102 calculated by the vehicle speed calculation unit 142. Furthermore, it determines whether this vehicle speed change amount ΔV is larger than the threshold value ΔVa determined by the threshold value determination unit 144. That is, it determines whether the vehicle speed change amount ΔV is equal to or larger than the threshold value ΔVa. If it is determined that ΔV≧ΔVa, it determines that the forward vehicle 102 has decelerated. This determination is a determination of whether the host vehicle 101 performs deceleration control, and ΔV0 is set to a value larger than 0. That is, the deceleration determination unit 145 does not determine whether the forward vehicle 102 has decelerated in the strict sense, but determines whether the degree of deceleration is equal to or greater than a predetermined level.

[0042] During following travel, when the deceleration determination unit 145 determines that the preceding vehicle 102 has decelerated (deceleration level is equal to or greater than a predetermined value), the travel control unit 16 outputs a control signal to the brake actuator to decelerate the host vehicle 101. At this time, the travel control unit 16 controls the actuator AC so as to apply a larger braking force the faster the vehicle speed of the host vehicle 101 detected by the vehicle speed sensor 2a is and the larger the rate of change of the relative vehicle speed (degree of approach). Note that when deceleration is detected that is less than a predetermined value, the travel control unit 16 issues a command to, for example, release the accelerator pedal without driving the brake actuator.

[0043] Fig. 5 is a flowchart showing an example of a process executed by the controller 10 of Fig. 3. The process shown in this flowchart is started, for example, when the preceding vehicle 102 is recognized during following travel, and is repeated at a predetermined cycle as long as following travel continues.

[0044] As shown in Fig. 5, first, in step S1, signals are read from the detectors 1a to 1c and the vehicle speed sensor 2a. Next, in step S2, it is determined whether or not the brake lights of the forward vehicle 102 are on, based on the signal from the object detector 1a (camera) read in step S1. Next, in step S3, the relationship in Fig. 4 stored in advance in the storage unit 12 is referenced, and a threshold value ΔVa is determined according to the brightness detected by the brightness detector, the amount of rainfall detected by the rainfall detector 1b, and the on / off state of the brake lights determined in step S2.

[0045] Next, in step S4, a vehicle speed change amount ΔV of the forward vehicle 102 is calculated. Specifically, a relative vehicle speed Vα of the forward vehicle 102 with respect to the host vehicle 101 is calculated based on a signal from the object detector 1a, and the vehicle speed V1 of the host vehicle obtained based on a signal from the vehicle speed sensor 2a is added to the relative vehicle speed Vα to calculate a vehicle speed V2 of the forward vehicle 102. A change amount per unit time of this vehicle speed V2 is calculated as a vehicle speed change amount ΔV. Next, in step S5, it is determined whether the vehicle speed change amount ΔV calculated in step S4 is equal to or greater than the threshold value ΔVa determined in step S3.

[0046] If the result in step S5 is affirmative, the process proceeds to step S6, and if the result is negative, step S6 is skipped and the process ends. If the result in step S5 is affirmative, it is determined that the forward vehicle 102 has decelerated. Therefore, in step S6, a control signal is output to the brake actuator to decelerate the host vehicle 101. That is, deceleration control is executed. With the above, the process ends.

[0047] The operation of the deceleration detection device 50 according to this embodiment will be described in more detail. Fig. 6A shows an example in which the host vehicle 101 is following the vehicle 102 ahead when there is no rainfall. In this case, the position of the vehicle 102 ahead detected by the object detector 1a is in area A, and the position of the vehicle 102 ahead can be recognized with high accuracy. For this reason, the normal value ΔVa0 is used as the threshold value ΔVa for deceleration detection.

[0048] 6B is an example of following travel in a state where the weather has deteriorated (for example, heavy rain). In this case, the position of the preceding vehicle 102 detected by the object detector 1a is in area A, and the position of the preceding vehicle 102 based on the detection value is detected closer to the vehicle itself than it actually is, and the position detection accuracy is reduced. In this case, the threshold value ΔVa is set to a value (for example, ΔVa2) smaller than the normal threshold value ΔVa0. This makes it easier to detect deceleration even if the position detection accuracy is reduced, making it easier to perform deceleration control.

[0049] FIG. 6C shows another example of following travel in worsening weather conditions (e.g., heavy rain) in which the brake lights of the preceding vehicle 102 are turned on. In this case, the position of the preceding vehicle 102 detected by the object detector 1a is in area A, and the position detection accuracy is higher than that of FIG. 6B. At this time, the threshold value ΔVa is set to a value (e.g., ΔVa3) smaller than the threshold value ΔVa2 when the brake lights are not turned on. This makes it easier to detect deceleration when the brake lights are turned on, which is almost certain to occur, and makes it easier to perform deceleration control.

[0050] According to this embodiment, the following advantageous effects can be obtained. (1) The deceleration detection device 50 includes an object detector 1a for detecting objects around the vehicle 101, a rainfall detector 1b for detecting the rainfall condition around the vehicle 101, a brightness detector 1c for detecting the brightness around the vehicle 101, and a deceleration determination unit 145 for determining whether the vehicle 102 is decelerating based on the change in vehicle speed V2 of the vehicle 102 traveling ahead of the vehicle 101 detected by the object detector 1a, the brake light condition of the vehicle 102 detected by the object detector 1a (camera), the rainfall condition detected by the rainfall detector 1b, and the brightness detected by the brightness detector 1c (FIG. 3). In this way, the deceleration of the vehicle 102 can be accurately detected by considering the rainfall condition, the brightness, and the brake light condition.

[0051] (2) The deceleration determination unit 145 determines that the forward vehicle 102 has decelerated when the change amount ΔV in the vehicle speed V2 of the forward vehicle 102 becomes equal to or greater than a threshold value ΔVa that is set according to brightness, rainfall conditions, and the illumination state of the brake lamps (FIG. 5). This makes it easy to determine whether the forward vehicle 102 has decelerated.

[0052] (3) The threshold value ΔVa is set to a first threshold value ΔVa0 when rain is not detected by the rain detector 1b and the object detector 1a does not detect the brake lamp illumination. When rain is detected by the rain detector 1b and the object detector 1a does not detect the brake lamp illumination, the threshold value ΔVa is set to a second threshold value (for example, ΔVa2) smaller than Va0. When rain is detected by the rain detector 1b and the object detector 1a detects the brake lamp illumination, the threshold value ΔVa is set to a third threshold value (for example, ΔVa3) smaller than ΔVa2 (FIG. 4). In this way, the threshold value ΔVa is made smaller in the case of heavy rain or other rainfall conditions (ΔVa0>ΔVa2), so that the delay in the timing of deceleration detection of the forward vehicle 102 can be suppressed. In addition, the threshold value ΔVa is further made smaller when the brake lamp is illuminated (ΔVa2>ΔVa3), so that when the brake lamp is illuminated and the certainty of deceleration is high, deceleration detection can be performed quickly and deceleration control can be executed at an appropriate timing.

[0053] The above embodiment can be modified in various ways. Some modified examples will be described below. In the above embodiment, the forward vehicle 102 is detected by a camera, a radar, or a lidar as the object detector 1a, but the configuration of the object detection unit is not limited to the above. In the above embodiment, the rainfall state around the vehicle 101 is detected by the rainfall detector 1b, but the configuration of the rainfall detection unit is not limited to the above. In the above embodiment, the brightness detector 1c is used to detect the brightness around the vehicle 101, but the configuration of the brightness detection unit is not limited to the above.

[0054] In the above embodiment, when the change amount ΔV of the vehicle speed V2 of the forward vehicle 102 becomes equal to or greater than the threshold value ΔVa set according to the brightness, the rainfall state, and the on-state of the brake lamps (braking lights), the forward vehicle 102 is determined to have decelerated, and deceleration control is performed. However, the configuration of the deceleration determination unit may be any as long as the presence or absence of deceleration of the forward vehicle is determined based on the change amount of the vehicle speed, the on-state of the brake lamps, the rainfall state, and the brightness. In the above embodiment, the relationship between the brightness, the rainfall state, the on-state of the brake lamps, and the multiple threshold values ​​ΔVa0 to ΔVa5 is stored in advance in the storage unit 12, and the threshold value ΔVa is determined using this relationship. However, the threshold value ΔVa may be determined by performing a predetermined calculation using the brightness, the rainfall state, and the on-state of the brake lamps as parameters. The relationship in FIG. 4 is an example, and the threshold value ΔVa may be determined by dividing the brightness and the rainfall state into more or fewer stages.

[0055] In the above embodiment, when deceleration of the vehicle 102 ahead is detected, the deceleration control of the vehicle 101 is performed, but the driver may be notified of the deceleration of the vehicle 102 ahead via a monitor or the like. This allows the driver to perform a brake operation at an appropriate timing when the vehicle 101 is driven manually.

[0056] The above description is merely an example, and the present invention is not limited to the above-mentioned embodiment and modifications, as long as the features of the present invention are not impaired. The above-mentioned embodiment and one or more modifications can be arbitrarily combined, and modifications can be combined with each other. [Explanation of symbols]

[0057] 1a object detector, 1b rainfall detector, 1c brightness detector, 2a vehicle speed sensor, 10 controller, 50 deceleration detection device, 101 vehicle, 102 forward vehicle, 143 lamp illumination determination unit, 144 threshold determination unit, 145 deceleration determination unit, ΔVa threshold

Claims

[Claim 1] an object detection unit that detects objects around the host vehicle; A rainfall detection unit that detects a rainfall state around the vehicle; A brightness detection unit that detects the brightness around the vehicle; a deceleration determination unit that determines whether or not the forward vehicle is decelerating based on an amount of change in vehicle speed of a forward vehicle traveling in front of the host vehicle detected by the object detection unit, a lighting state of the brake lights of the forward vehicle detected by the object detection unit, a rainfall state detected by the rainfall detection unit, and a brightness detected by the brightness detection unit, the deceleration determination unit determines that the forward vehicle has decelerated when a change in vehicle speed of the forward vehicle becomes equal to or greater than a threshold value that is set according to brightness, a rainfall state, and a lighting state of the brake lights; The threshold value is When the rainfall detection unit does not detect rainfall and the object detection unit does not detect illumination of the brake lights, the threshold value is set to a first threshold value; when rain is detected by the rain detection unit and illumination of the brake lights is not detected by the object detection unit, a second threshold value is set to be smaller than the first threshold value; A deceleration detection device, characterized in that when rain is detected by the rain detection unit and the object detection unit detects that the brake lights are on, the deceleration detection unit sets a third threshold value that is smaller than the second threshold value.

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