Deceleration detection device

Abstract

The present invention provides a deceleration detection device, comprising: an object detection unit (1a) for detecting objects around the vehicle (101); a rainfall detection unit (1b) for detecting rainfall around the vehicle (101); a brightness detection unit (1c) for detecting brightness around the vehicle (101); and a deceleration determination unit (145) for determining whether the vehicle (102) in front has decelerated based on the change in speed of the vehicle (102) in front, the illumination status of the brake lights of the vehicle (102) in front, the rainfall status, and the brightness.

Description

Technical Field

[0001] This invention relates to a deceleration detection device for detecting the deceleration of a vehicle ahead. Background Technology

[0002] Previously, there were known devices that used sensor fusion of radar and camera to identify a vehicle traveling in front of the vehicle and control the automatic braking system based on the identification result. Such a device is described, for example, in Patent Document 1.

[0003] However, due to the influence of weather or external light, it is sometimes difficult to detect the deceleration of vehicles ahead with high accuracy, even through sensor fusion.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2005-329779 (JP2005-329779A). Summary of the Invention

[0007] A deceleration detection device according to one embodiment of the present invention comprises: an object detection unit that detects objects around the vehicle; a rainfall detection unit that detects the rainfall around the vehicle; a brightness detection unit that detects the brightness around the vehicle; and a deceleration determination unit that determines whether the vehicle in front has decelerated based on the change in speed of the vehicle in front of the vehicle detected by the object detection unit, the illumination state of the brake lights of the vehicle in front detected by the object detection unit, the rainfall state detected by the rainfall detection unit, and the brightness detected by the brightness detection unit. Attached Figure Description

[0008] The objectives, features, and advantages of the present invention are further illustrated by the following description of embodiments in conjunction with the accompanying drawings.

[0009] Figure 1 This is a block diagram that schematically illustrates the overall structure of a vehicle control system having a deceleration detection device according to an embodiment of the present invention.

[0010] Figure 2 This is a diagram illustrating an example of a driving scenario of the vehicle equipped with the deceleration detection device according to an embodiment of the present invention.

[0011] Figure 3 This is a block diagram illustrating the main structural components of a deceleration detection device according to an embodiment of the present invention.

[0012] Figure 4 This is a graph showing the relationship between the threshold for deceleration determination used in the deceleration detection device according to an embodiment of the present invention and brightness, rainfall, and the illumination state of the brake lights.

[0013] Figure 5 It is shown by Figure 3 A flowchart of an example of the processing performed by the controller.

[0014] Figure 6A This is a diagram illustrating an example of the operation of the deceleration detection device according to an embodiment of the present invention.

[0015] Figure 6B This is a diagram illustrating another example of the operation of the deceleration detection device according to an embodiment of the present invention.

[0016] Figure 6C This is a diagram illustrating yet another example of the operation of the deceleration detection device according to an embodiment of the present invention. Detailed Implementation

[0017] See below. Figures 1 to 6C Embodiments of the present invention will be described. The deceleration detection device of the present invention can be applied to vehicles with autonomous driving functions, i.e., both autonomous vehicles and manually driven vehicles without autonomous driving functions. Examples of applying the deceleration detection device to autonomous vehicles will be described below. It should be noted that sometimes the vehicle to which the deceleration detection device of this embodiment is applied is referred to as "this vehicle" to distinguish it from other vehicles.

[0018] This vehicle can be any of the following: an engine vehicle with an internal combustion engine as the driving source, an electric vehicle with an electric motor as the driving source, or a hybrid vehicle with both an engine and an electric motor as driving sources. This vehicle (autonomous driving vehicle) can operate not only in an autonomous driving mode that does not require driver operation, but also in a manual driving mode based on driver operation.

[0019] First, let's explain the general structure related to autonomous driving. Figure 1 This is a block diagram schematically illustrating the overall structure of a vehicle control system 100 having a deceleration detection device according to an embodiment of the present invention. Figure 1 As shown, the vehicle control system 100 mainly includes a controller 10 and external sensor group 1, internal sensor group 2, input / output device 3, positioning unit 4, map database 5, navigation device 6, communication unit 7, and driving actuator AC, which are communicatively connected to the controller 10 via CAN (Controller Area Network) communication line, etc.

[0020] External sensor group 1 is a collective term for multiple sensors (external sensors) that detect external conditions that serve as information about the vehicle's surroundings. For example, external sensor group 1 includes lidar, radar, and cameras. Lidar detects the position (distance and direction from the vehicle) of objects around the vehicle by irradiating a laser and detecting the reflected light; radar detects the position of objects around the vehicle by irradiating electromagnetic waves and detecting the reflected waves; and the camera captures images of the vehicle's surroundings.

[0021] Internal sensor group 2 is a collective term for multiple sensors (internal sensors) that detect the driving status of the vehicle. For example, internal sensor group 2 includes a vehicle speed sensor to detect the vehicle's speed, an acceleration sensor to detect the vehicle's acceleration in the forward and backward and left and right directions, and a speed sensor to detect the rotational speed of the driving source. Sensors that detect the driver's driving operations in manual driving mode, such as operation of the accelerator pedal, operation of the brake pedal, and operation of the steering wheel, are also included in internal sensor group 2.

[0022] Input / output device 3 is a general term for devices that input commands to the driver and output information to the driver. For example, input / output device 3 includes: various switches for the driver to input various commands by operating control components; a microphone for the driver to input commands by voice; a display that provides information to the driver using displayed images; and a speaker that provides information to the driver by voice. The various switches include manual / automatic switching switches for either automatic driving mode or manual driving mode.

[0023] The positioning unit (GNSS unit) 4 has a positioning sensor that receives positioning signals transmitted from positioning satellites. Positioning satellites are artificial satellites such as GPS (Global Positioning System) satellites and quasi-zenith satellites. The positioning unit 4 uses the positioning information received by the positioning sensor to determine the vehicle's current position (latitude, longitude, and altitude).

[0024] Map database 5 is a device that stores general map information for navigation device 6, and is composed of, for example, a hard disk or semiconductor components. The map information includes road location information, road shape (curvature, etc.) information, and the location information of intersections or forks in the road. It should be noted that the map information stored in map database 5 is different from the high-precision map information stored in storage unit 12 of controller 10.

[0025] The navigation device 6 is a device that searches for a target path on the road leading to the destination input by the driver and guides the driver along the target path. The destination is input and the driver is guided along the target path via the input / output device 3. The target path is calculated based on the current position of the vehicle determined by the positioning unit 4 and map information stored in the map database 5. Alternatively, the current position of the vehicle can be determined using the detection values ​​of the external sensor group 1, and the target path can be calculated based on the current position and high-precision map information stored in the storage unit 12.

[0026] Communication unit 7 communicates with various servers (not shown) via networks including wireless communication networks such as the Internet or mobile phone networks, periodically or at any time, to obtain map information, driving history information, and traffic information from the servers. It may also not only obtain driving history information but also send the vehicle's driving history information to the server via communication unit 7. The network includes not only public wireless communication networks but also closed communication networks set up for each designated management area, such as wireless LAN (Wireless Local Area Network), Wi-Fi, and Bluetooth. The obtained map information is output to map database 5 and storage unit 12 to update the map information.

[0027] An actuator (AC) is a driving actuator used to control the movement of the vehicle. When the driving source is an engine, the actuator AC includes a throttle actuator for adjusting the opening of the engine's throttle valve (throttle opening). When the driving source is a travel motor, the travel motor is included in the actuator AC. Braking actuators that operate the vehicle's braking system and steering actuators that drive the steering system are also included in the actuator AC.

[0028] The controller 10 is composed of an electronic control unit (ECU). More specifically, the controller 10 is configured as a computer including an arithmetic unit 11 such as a CPU (microprocessor), a storage unit 12 such as ROM (read-only memory) and RAM (random access memory), and other peripheral circuits not shown, such as I / O (input / output) interfaces. It should be noted that multiple ECUs with different functions, such as an engine control ECU, a drive motor control ECU, and a braking system ECU, can be set up separately, but... Figure 1 For convenience, controller 10 is shown as a collection of these ECUs.

[0029] High-precision road map information is stored in storage unit 12. This road map information includes road location information, road shape (curvature, etc.) information, road slope information, intersection or fork location information, number of lanes information, lane width and position information of each lane (center position of the lane, lane boundary information), position information of landmarks (traffic lights, signs, buildings, etc.) that serve as markers on the map, and road surface features such as unevenness. The map information stored in storage unit 12 includes map information obtained from outside the vehicle via communication unit 7 and map information created by the vehicle itself using detection values ​​from external sensor group 1 or detection values ​​from external sensor group 1 and internal sensor group 2.

[0030] The computing unit 11 has a functional structure including a vehicle position recognition unit 13, an external recognition unit 14, an action plan generation unit 15, and a driving control unit 16.

[0031] The vehicle position recognition unit 13 identifies the vehicle's position on the map (vehicle position) based on the vehicle's position information obtained from the positioning unit 4 and the map information from the map database 5. Alternatively, the vehicle position can be identified using map information stored in the storage unit 12 and surrounding information detected by the external sensor group 1, thereby enabling high-precision vehicle position identification. It should be noted that when the vehicle's position can be determined using external sensors installed on or beside the road, the vehicle position can also be identified by communicating with these sensors via the communication unit 7.

[0032] The external identification unit 14 identifies the external conditions around the vehicle based on signals from the external sensor group 1, such as lidar, radar, and cameras. For example, it identifies the position, speed, and acceleration of surrounding vehicles (vehicles in front and behind) traveling around the vehicle, the position of surrounding vehicles parked or stationary around the vehicle, and the position and state of other objects. Other objects include signs, traffic lights, road markings, stop lines, buildings, guardrails, utility poles, signs, pedestrians, and bicycles. The state of other objects includes the color of traffic lights (red, blue, yellow), and the speed and direction of movement of pedestrians or bicycles.

[0033] The action plan generation unit 15 generates a driving trajectory (target trajectory) of the vehicle from the current point in time to a predetermined time, based on, for example, the target path calculated by the navigation device 6, map information stored in the storage unit 12, the vehicle position identified by the vehicle position recognition unit 13, and the external conditions identified by the external environment recognition unit 14. When multiple candidate trajectories exist on the target path, the action plan generation unit 15 selects the optimal trajectory that meets criteria such as compliance with laws and efficient and safe driving, and designates the selected trajectory as the target trajectory. Then, the action plan generation unit 15 generates an action plan corresponding to the generated target trajectory. The action plan generation unit 15 generates various action plans corresponding to overtaking, lane changing, following, lane keeping, deceleration, and acceleration. When generating the target trajectory, the action plan generation unit 15 first determines the driving mode and generates the target trajectory based on the driving mode.

[0034] In autonomous driving mode, the driving control unit 16 controls each actuator AC to make the vehicle travel along the target trajectory generated by the action plan generation unit 15. More specifically, the driving control unit 16 considers the driving resistance determined by road gradient and other factors in autonomous driving mode, and calculates the required driving force to obtain the target acceleration per unit time calculated by the action plan generation unit 15. Furthermore, for example, feedback control is applied to the actuator ACs to make the actual acceleration detected by the internal sensor group 2 the target acceleration. That is, the actuator ACs are controlled to make the vehicle travel at the target speed and target acceleration. It should be noted that in manual driving mode, the driving control unit 16 controls each actuator AC based on driving commands (steering operations, etc.) obtained from the driver by the internal sensor group 2.

[0035] Figure 2 This illustrates an example where the vehicle 101 travels at a speed of V1 while following a vehicle 102 traveling in front of it. During this following motion, the vehicle speed V2 of the vehicle 102 is calculated based on signals from the external sensor group 1, and the deceleration of the vehicle 102 is detected based on the change in speed V2 ΔV.

[0036] However, the detection accuracy of the external sensor group 1, including radar, lidar, and cameras, can sometimes be affected by weather and ambient light. For example, during heavy rainfall, the scattering of light caused by the rain can affect the detection accuracy of lidar, and consequently, the radar's detection accuracy will also be affected. In this situation, it will also affect the edge detection of the camera. In addition, strong light sources, such as bright sunlight, will affect the edge detection of the camera, and the detection accuracy will also be affected in backlit conditions or in low-light conditions such as at night.

[0037] Thus, when affected by weather or brightness, the accuracy of the detection values ​​from the external sensor group 1, detected at a predetermined period, decreases, and the position of the vehicle 102 in front, identified based on the detection values, may temporarily shift backward compared to the actual position. Figure 2 Area A1) or shifted forward ( Figure 2 (Region A2). That is, the coordinates of the detected value may jump instantaneously. As a result, the accuracy of measuring the deceleration or speed change of the vehicle 102 ahead is reduced, which may affect following. Therefore, this embodiment is configured as follows to detect the speed change of the vehicle 102 ahead, especially deceleration, with high accuracy, regardless of weather or brightness.

[0038] Figure 3 This is a block diagram showing the main structural components of a deceleration detection device 50 according to an embodiment of the present invention. The deceleration detection device 50 comprises... Figure 1 It is part of the vehicle control system 100. For example... Figure 3 As shown, the deceleration detection device 50 includes an object detector 1a, a rainfall detector 1b, a brightness detector 1c, a vehicle speed sensor 2a, and an actuator AC.

[0039] Object detector 1a is, for example, a single-lens camera with imaging elements (image sensors) such as CCD (charge-coupled device) and CMOS (complementary metal-oxide-semiconductor), constituting... Figure 1 It is part of the external sensor group 1. The camera can be a stereo camera. The camera is mounted, for example, at a predetermined position at the front of the vehicle 101, and continuously captures images of the space in front of the vehicle 101 to obtain images of objects (camera images). The objects include the vehicle 102 in front, and images of the brake lights at the rear of the vehicle 102 in front are obtained. In addition to the camera, the object detector 1a also includes either or both of radar and lidar. That is, it includes a distance detector that detects the distance between the vehicle 101 and the object (the vehicle 102 in front).

[0040] Rainfall detector 1b is a detector that detects the presence and amount of raindrops (rainfall), and can be constructed from a raindrop sensor. The raindrop sensor is, for example, mounted on the outside of the windshield. Alternatively, a wiper sensor can be installed to detect the movement of the windshield wipers, and the amount of rainfall can be detected (inferred) by the wiper sensor. Brightness detector 1c is a detector that detects ambient brightness (illuminance), and can be constructed from an illuminance sensor. The illuminance sensor is, for example, mounted on the inside of the windshield. Rainfall detector 1b and brightness detector are also configured... Figure 1 It is part of the external sensor group 1. The vehicle speed sensor 2a detects the speed of the vehicle 101. The vehicle speed sensor 2a constitutes... Figure 1 It is part of the internal sensor group 2.

[0041] In addition to the driving control unit 16, the controller 10 also includes a vehicle recognition unit 141, a vehicle speed calculation unit 142, a light illumination determination unit 143, a threshold determination unit 144, and a deceleration determination unit 145 as a calculation unit 11. Figure 1 The functional structure undertaken by the vehicle recognition unit 141, vehicle speed calculation unit 142, light illumination determination unit 143, threshold determination unit 144, and deceleration determination unit 145 is provided for detecting the driving status of the vehicle 102 ahead, for example by... Figure 1 It consists of an external identification unit 14.

[0042] The vehicle identification unit 141 identifies the presence or absence of a vehicle 102 ahead based on a signal from the object detector 1a. For example, when following the vehicle 102 ahead at a predetermined inter-vehicle distance, the vehicle 102 ahead is identified. The inter-vehicle distance between the identified vehicle 102 ahead and the vehicle 101 is detected by the object detector 1a (distance detector).

[0043] The vehicle speed calculation unit 142 calculates the relative speed Vα (=V1-V2) between the vehicle speed V1 of the current vehicle 101 and the vehicle speed V2 of the vehicle ahead 102 by performing time differentiation on the inter-vehicle distance detected by the object detector 1a. The vehicle speed V1 of the current vehicle 101 detected by the vehicle speed sensor 2a is added to the relative speed Vα to calculate the vehicle speed V2 of the vehicle ahead 102.

[0044] The brake light illumination determination unit 143 determines whether the brake lights of the vehicle 102 ahead are illuminated based on the signal from the object detector 1a. Whether the brake lights are illuminated can be determined by determining whether a red area with a brightness of a predetermined value or higher is detected in front of the vehicle 101. Therefore, even in cases of heavy rainfall or when the ambient brightness is above the predetermined value, the brake light illumination determination unit 143 can easily and accurately determine whether the brake lights are illuminated.

[0045] The threshold determination unit 144 determines the threshold value ΔV for determining whether the vehicle ahead 102 has decelerated. More specifically, based on the rainfall detected by the rainfall detector 1b, the brightness detected by the brightness detector 1c, and the brake light illumination status determined by the light illumination determination unit 143, the threshold value ΔVa is selected from a plurality of threshold values ​​ΔVa pre-stored in the storage unit 12.

[0046] Figure 4 This is a graph showing the relationship between brightness, rainfall, brake light illumination status, and threshold ΔVa. Figure 4In the system, brightness is divided into two levels: daytime and nighttime. Specifically, when the brightness (illuminance) Lx is above the specified value Lx1, it is considered daytime; when it is below Lx1, it is considered nighttime. Rainfall is divided into four levels: zero, light rain, heavy rain, and torrential rain. Specifically, rainfall R greater than 0 and less than the specified value R1 is light rain; rainfall greater than R1 and less than the specified value R2 (>R1) is heavy rain; and rainfall greater than R2 is torrential rain. This rainfall corresponds to the wiper operation (zero, intermittent, low, high). Therefore, the wiper operation can be used to determine the threshold ΔVa instead of the rainfall. Brake light illumination is divided into two levels: non-illuminated and illuminated.

[0047] Threshold determination unit 144 uses Figure 4 The threshold ΔVa is determined by the relationship between ΔVa0 and ΔVa5. It should be noted that the threshold ΔVa is an absolute value, and the relationship exists as ΔVa0 > ΔVa1 > ΔVa2 > ΔVa3 > ΔVa4 > ΔVa5. More specifically, when the brightness is daytime and the rainfall is zero, the threshold determination unit 144 determines the threshold to ΔVa0 in both cases where the brake lights are on and off. In light rain, if the brake lights are off, the threshold is determined to be ΔVa0; if they are on, it is determined to be ΔVa1. In heavy rain, if the brake lights are off, the threshold is determined to be ΔVa1; if they are on, it is determined to be ΔVa2. In torrential rain, if the brake lights are off, the threshold is determined to be ΔVa2; if they are on, it is determined to be ΔVa3.

[0048] On the other hand, when the brightness is at night and the rainfall is zero, the threshold determination unit 144 determines the threshold to be ΔVa0 in either the case where the brake lights are not lit or lit. When the rainfall is light, if the brake lights are not lit, the threshold is determined to be ΔVa1; if they are lit, it is determined to be ΔVa2. When the rainfall is heavy, if the brake lights are not lit, the threshold is determined to be ΔVa2; if they are lit, it is determined to be ΔVa3. When the rainfall is torrential, if the brake lights are not lit, the threshold is determined to be ΔVa4; if they are lit, the threshold is determined to be ΔVa5. Thus, the dimmer the brightness and the greater the rainfall, the smaller the threshold ΔVa is determined to be. Furthermore, when the rainfall is not zero, if the brake lights are lit, the threshold ΔVa is determined to be a smaller value than in the case where they are not lit.

[0049] It should be noted that the threshold ΔVa for the change in vehicle speed ΔV is not solely determined by factors such as brightness, rainfall, and the illumination status of the brake lights. Instead, it is determined by factors such as the vehicle speed V1 of the current vehicle 101 and the distance between it and the vehicle in front. For example, the threshold ΔVa0 is approximately 2–3 m / s.

[0050] The deceleration determination unit 145 calculates the change in speed V2 of the vehicle ahead 102 per unit time, calculated by the vehicle speed calculation unit 142, by a value ΔV. Then, it determines whether this speed change ΔV is greater than or equal to a threshold ΔVa determined by the threshold determination unit 144. Specifically, it determines whether the speed change ΔV is greater than or equal to the threshold ΔVa. If ΔV ≥ ΔVa, it determines that the vehicle ahead 102 has decelerated. This determination is for whether the vehicle 101 has implemented deceleration control, and ΔV0 is set to a value greater than 0. That is, the deceleration determination unit 145 does not determine whether the vehicle ahead 102 has decelerated in a strict sense, but rather whether the degree of deceleration is at or above a predetermined level.

[0051] When following another vehicle, if the deceleration determination unit 145 determines that the vehicle 102 ahead has decelerated (to a level greater than or equal to a specified value), the driving control unit 16 outputs a control signal to the brake actuator to decelerate the vehicle 101. At this time, the faster the vehicle speed of the vehicle 101 detected by the vehicle speed sensor 2a and the greater the rate of change (closeness) of the relative vehicle speed, the driving control unit 16 controls the actuator AC to apply a greater braking force. It should be noted that if deceleration of less than a specified level is detected, the brake actuator is not activated; instead, the accelerator pedal is released, for example.

[0052] Figure 5 It is shown by Figure 3 The flowchart illustrates an example of the processing performed by the controller 10. The processing shown in the flowchart begins, for example, when a vehicle 102 ahead is detected during following, and repeats at a predetermined cycle as long as following continues.

[0053] like Figure 5 As shown, firstly, in step S1 (S: processing step), signals from each detector 1a-1c and the vehicle speed sensor 2a are read in. Next, in step S2, based on the signal read in step S1 from the object detector 1a (camera), it is determined whether the brake lights of the vehicle 102 ahead are illuminated. Then, in step S3, the system references signals pre-stored in the storage unit 12. Figure 4 The relationship shown is based on the brightness detected by the brightness detector, the amount of rainfall detected by the rainfall detector 1b, and the brake light illumination status determined in S2, which determines the threshold ΔVa.

[0054] Next, in S4, the speed change ΔV of the vehicle ahead 102 is calculated. Specifically, the relative speed Vα of the vehicle ahead 102 relative to the vehicle 101 is calculated based on the signal from the object detector 1a, and the vehicle speed V1 of the vehicle ahead 102 obtained from the signal from the vehicle speed sensor 2a is added to the relative speed Vα to calculate the speed V2 of the vehicle ahead 102. The change in speed V2 per unit time is calculated as the speed change ΔV. Then, in S5, it is determined whether the speed change ΔV calculated in S4 is above the threshold ΔVa determined in S3.

[0055] When S5 is affirmative (S5: Yes), proceed to S6; when it is negative (S5: No), skip S6 and end the process. When S5 is affirmative (S5: Yes), it is determined that the vehicle 102 ahead has decelerated. Therefore, in S6, a control signal is output to the braking actuator to decelerate the vehicle 101. That is, deceleration control is executed. The process ends here.

[0056] The operation of the deceleration detection device 50 in this embodiment will be explained in more detail. Figure 6A This example illustrates a scenario where vehicle 101 follows vehicle 102 in the presence of zero rainfall. In this case, the position of vehicle 102 detected by object detector 1a is region A, enabling high-precision identification of the vehicle 102's position. Therefore, the deceleration detection threshold ΔVa uses the usual value (reference value) ΔVa0.

[0057] Figure 6B This is an example of following a vehicle in adverse weather conditions (e.g., heavy rain). In this situation, the position of the vehicle ahead 102 detected by the object detector 1a is in region A. Based on the detected value, the position of the vehicle ahead 102 is detected as being closer to the vehicle than it actually is, resulting in reduced position detection accuracy. At this time, the threshold ΔVa is set to a value smaller than the usual threshold ΔVa0 (e.g., ΔVa2). Therefore, even with reduced position detection accuracy, deceleration is easily detected, making deceleration control easier.

[0058] Figure 6C Another example of following a vehicle in deteriorating weather (e.g., heavy rain) is when the brake lights of the vehicle ahead 102 are illuminated. In this case, the position of the vehicle ahead 102 detected by the object detector 1a is region A, and the position detection accuracy is higher than... Figure 6B In this case, the threshold ΔVa is set to a value smaller than the threshold ΔVa2 when the brake light is not illuminated (e.g., ΔVa3). This makes it easier to detect deceleration when the brake light is illuminated, which reliably produces deceleration, thus making deceleration control easier.

[0059] According to this embodiment, the following effects can be achieved.

[0060] (1) The deceleration detection device 50 includes: an object detector 1a, which detects objects around the vehicle 101; a rain detector 1b, which detects the rainfall around the vehicle 101; a brightness detector 1c, which detects the brightness around the vehicle 101; and a deceleration determination unit 145, which determines whether the vehicle 102 is decelerating based on the change ΔV of the speed V2 of the vehicle 102 traveling in front of the vehicle 101 detected by the object detector 1a, the illumination status of the brake lights of the vehicle 102 detected by the object detector 1a (camera), the rainfall status detected by the rain detector 1b, and the brightness detected by the brightness detector 1c. Figure 3 In this way, by taking into account the rainfall conditions, brightness, and the illumination status of the brake lights, the deceleration of the vehicle 102 ahead can be detected with high precision.

[0061] (2) When the deceleration determination unit 145 determines that the vehicle ahead 102 has decelerated when the change in speed V2 ΔV of the vehicle ahead 102 exceeds the threshold ΔVa set based on brightness, rainfall conditions, and brake light illumination status, the deceleration determination unit 145 determines that the vehicle ahead 102 has decelerated. Figure 5 Therefore, it is easy to determine whether vehicle 102 ahead has slowed down.

[0062] (3) When the rain detector 1b does not detect rainfall and the object detector 1a does not detect the brake light being lit, the threshold ΔVa is set to the first threshold ΔVa0. When the rain detector 1b detects rainfall and the object detector 1a does not detect the brake light being lit, the threshold ΔVa is set to a second threshold (e.g., ΔVa2) that is less than Va0. When the rain detector 1b detects rainfall and the object detector 1a detects the brake light being lit, the threshold ΔVa is set to a third threshold (e.g., ΔVa3) that is less than ΔVa2. Figure 4 In this way, by reducing the threshold ΔVa (ΔVa0>ΔVa2) under rainfall conditions such as heavy rain, the delay in detecting the deceleration of the vehicle 102 ahead can be suppressed. Furthermore, by further reducing the threshold ΔVa (ΔVa2>ΔVa3) when the brake lights are illuminated, deceleration detection can be performed quickly when the reliability of deceleration upon brake light illumination is high, and deceleration control can be executed at the appropriate time.

[0063] The above embodiments can be modified in various ways. Several modifications will be described below. In the above embodiments, a camera, radar, or lidar is used as the object detector 1a to detect the vehicle 102 ahead, but the configuration of the object detection unit is not limited to the above configuration. In the above embodiments, a rain detector 1b detects the rainfall conditions around the vehicle 101, but the configuration of the rain detection unit is not limited to the above configuration. In the above embodiments, a brightness detector 1c detects the brightness around the vehicle 101, but the configuration of the brightness detection unit is not limited to the above configuration.

[0064] In the above embodiment, when the change in speed V2 of the vehicle ahead 102, ΔV, exceeds a threshold ΔVa set based on brightness, rainfall conditions, and the illumination status of the brake lights, it is determined that the vehicle ahead 102 has decelerated and deceleration control is implemented. However, as long as the determination of whether the vehicle ahead has decelerated is based on the change in speed, the illumination status of the brake lights, rainfall conditions, and brightness, the configuration of the deceleration determination unit can be arbitrary. In the above embodiment, the relationship between brightness, rainfall conditions, the illumination status of the brake lights, and multiple thresholds ΔVa0 to ΔVa5 is stored in the storage unit 12 in advance, and the threshold ΔVa used for deceleration control is determined using this relationship. However, the threshold ΔVa can also be determined by performing a prescribed calculation using brightness, rainfall conditions, and the illumination status of the brake lights as parameters. Figure 4 The relationship is one example; the threshold ΔVa can also be determined by dividing brightness and rainfall status into more or fewer levels.

[0065] In the above embodiment, when the deceleration of the vehicle 102 ahead is detected, the vehicle 101 is decelerated. However, the driver can also be notified of the deceleration of the vehicle 102 ahead via a monitor or similar means. Thus, when the vehicle 101 is being driven manually, the driver can apply the brakes at an appropriate time.

[0066] The present invention can also be used as a deceleration detection method, which includes the following steps: detecting objects around the vehicle 101; detecting the rainfall status around the vehicle 101; detecting the brightness around the vehicle 101; and determining whether the vehicle 102 has decelerated based on the change in speed of the vehicle 102 traveling in front of the vehicle 101 and the illumination status of the brake lights of the vehicle 102 detected in the step of detecting objects, the rainfall status detected in the step of detecting rainfall status, and the brightness detected in the step of detecting brightness.

[0067] It is possible to combine one or more of the above-described embodiments and variations, and to combine the variations with each other.

[0068] Using this invention, even in adverse weather conditions, it is possible to detect the deceleration of vehicles ahead with high precision.

[0069] The present invention has been described above in conjunction with preferred embodiments, but those skilled in the art should understand that various modifications and alterations can be made without departing from the scope of the following claims.

Claims

1. A deceleration detection device, characterized in that, have: The object detection unit (1a) detects objects around the vehicle (101); Rainfall detection unit (1b) detects the rainfall conditions around the vehicle (101); A brightness detection unit (1c) detects the brightness around the vehicle (101); and The deceleration determination unit (145) determines whether the vehicle in front (102) is decelerating based on the change in speed of the vehicle in front (102) traveling in front of the vehicle (101) detected by the object detection unit (1a), the illumination status of the brake lights of the vehicle in front (102) detected by the object detection unit (1a), the rainfall status detected by the rainfall detection unit (1b), and the brightness detected by the brightness detection unit (1c). When the deceleration determination unit (145) determines that the vehicle ahead (102) has decelerated when the change in the speed of the vehicle ahead (102) exceeds a threshold (ΔVa) set based on brightness, rainfall conditions, and the illumination status of the brake lights, the deceleration determination unit (145) determines that the vehicle ahead (102) has decelerated. When the rainfall detection unit (1b) does not detect rainfall and the object detection unit (1a) does not detect the illumination of the brake light, the threshold (ΔVa) is set to the first threshold (ΔVa0). When the rainfall detection unit (1b) detects rainfall and the object detection unit (1a) does not detect the brake light being lit, and it indicates that the brightness value detected by the brightness detection unit (1c) is above a predetermined value, the threshold (ΔVa) is set to the second threshold (ΔVa2). When the rainfall detection unit (1b) detects rainfall and the object detection unit (1a) detects the brake light being lit, the threshold (ΔVa) is set to a third threshold (ΔVa3) that is less than the second threshold (ΔVa2). When the rainfall detection unit (1b) detects rainfall and the object detection unit (1a) does not detect the illumination of the brake light and indicates that the brightness value detected by the brightness detection unit (1c) is less than the predetermined value, the threshold (ΔVa) is set to a fourth threshold (ΔVa4) that is less than the second threshold (ΔVa2).

2. The deceleration detection device according to claim 1, characterized in that, When the rainfall detection unit (1b) detects rainfall and the object detection unit (1a) detects that the brake light is lit and indicates that the brightness detected by the brightness detection unit (1c) is above the predetermined value, the threshold (ΔVa) is set to the third threshold (ΔVa3). When the rainfall detection unit (1b) detects rainfall and the object detection unit (1a) detects that the brake light is lit, indicating that the brightness value detected by the brightness detection unit (1c) is less than the specified value, the threshold (ΔVa) is set to a fifth threshold (ΔVa5) that is less than the third threshold (ΔVa3).

3. The deceleration detection device according to claim 1 or 2, characterized in that, The more rainfall detected per unit time by the rainfall detection unit (1b), the smaller the second threshold (ΔVa2) and the third threshold (ΔVa3) are set to.

4. A deceleration detection method, characterized in that, It includes the following steps: Detect objects around this vehicle (101); Detect the rainfall conditions around the vehicle (101); Detect the brightness around the vehicle (101); and Based on the change in speed of the vehicle (102) traveling in front of the vehicle (101) detected in the step of detecting the object, the illumination status of the brake lights of the vehicle (102) in front, the rainfall status detected in the step of detecting the rainfall status, and the brightness detected in the step of detecting the brightness, a determination step is taken to determine whether the vehicle (102) in front has decelerated. The determination step includes: when the change in the speed of the vehicle ahead (102) exceeds a threshold (ΔVa) set based on brightness, rainfall conditions, and the illumination status of the brake lights, it is determined that the vehicle ahead (102) has decelerated. The threshold (ΔVa) setting includes: When no rainfall is detected and the brake light is not activated, the threshold (ΔVa) is set to the first threshold (ΔVa0). When rainfall is detected and the brake light is not detected to be lit, and the detected brightness value is above a specified value, the threshold (ΔVa) is set to the second threshold (ΔVa2). When rainfall is detected and the brake light is activated, the threshold (ΔVa) is set to a third threshold (ΔVa3) that is less than the second threshold (ΔVa2). When rainfall is detected but the brake light is not detected to be lit, and the detected brightness value is less than the specified value, the threshold (ΔVa) is set to a fourth threshold (ΔVa4) that is less than the second threshold (ΔVa2).

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