Driving assistance devices, driving assistance methods, and storage media

Abstract

This disclosure provides a driving assistance device, a driving assistance method, and a storage medium. The driving assistance device includes: a traffic signal recognition device that recognizes the light pattern of a traffic signal located in front of the vehicle; and a control device that determines a predetermined position around the traffic signal as a target position and performs deceleration control to slow the vehicle down until the vehicle reaches the target position. The control device is configured to calculate a predicted speed of the vehicle at the time point at which it will reach the target position while decelerating at a predetermined deceleration pattern from the current time point, and to perform deceleration control in a first condition where the predicted speed is less than a threshold determined based on the traffic signal light pattern, and not perform deceleration control in a second condition where the predicted speed exceeds the threshold. The threshold for a traffic signal with a yellow light is smaller than the threshold for a red traffic signal.

Description

Technical Field

[0001] The present invention relates to a driving assistance device, driving assistance method, and driving assistance program that are mounted on a vehicle and identify the light patterns of a traffic signal and decelerate the vehicle based on the identification results. Background Technology

[0002] A known driving assistance device (hereinafter referred to as "prior device") is mounted on a vehicle and identifies the light pattern of a traffic signal and decelerates the vehicle based on the identification result (for example, see Patent Document 1 below). This prior device identifies the light pattern (light color) of a traffic signal ahead of the vehicle based on an image obtained from an onboard camera. Next, the prior device determines whether the driver is performing a driving operation to accelerate the vehicle based on the operation of the accelerator pedal by the driver. Then, if the prior device determines that "the driver is not performing a driving operation to accelerate the vehicle" and the traffic signal light pattern is "red or yellow," it predicts (calculates) the speed of the vehicle at the target location (near the traffic signal). If the prediction result is less than a threshold, the prior device performs deceleration control (deceleration control).

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2021-77012 Summary of the Invention

[0006] Here, if the traffic light turns yellow when the vehicle is near the traffic light, the driver may sometimes find it difficult to determine whether to slow down and stop near the traffic light, or to accelerate and pass through the traffic light. This situation is often referred to as a "dilemma zone." The existing device does not differentiate between the "red" and "yellow" states of the traffic light. Therefore, the existing device tends to perform deceleration control to stop the vehicle even when the light is "yellow." Consequently, there is a high probability that deceleration control will be implemented before the driver decides on their driving action in the dilemma zone. For example, there may be a situation where, at the moment the driver selects to pass through the intersection's traffic light (straight, right turn, or left turn), the aforementioned deceleration control has already been implemented, causing the vehicle's speed to decrease. In this case, even if the vehicle accelerates from that moment, the traffic light may turn red just before passing through the intersection or while already within the intersection.

[0007] One of the objectives of this invention is to provide a driving assistance device that suppresses the execution of excessive deceleration control in a dilemma zone.

[0008] In order to solve the above-mentioned problems, the driving assistance device (1) of the present invention is mounted on the vehicle.

[0009] The driving assistance device includes: a traffic signal recognition device (23) that recognizes the light pattern of a traffic signal (S) located in front of the vehicle; and a control device (10) that, when the light pattern of the traffic signal recognized by the traffic signal recognition device is a predetermined pattern, determines a predetermined position around the traffic signal as a target position (sp), and performs deceleration control to slow down the vehicle until the vehicle reaches the target position. The control device is configured to decelerate the vehicle in a predetermined deceleration pattern from the current time point until the target position is reached. The system calculates the vehicle's speed at the target location at a given time point and the predicted speed (vp). In a first condition where the predicted speed is less than a threshold (vpth) determined based on the traffic signal light pattern, the system performs deceleration control. In a second condition where the predicted speed is above the threshold, the system does not perform deceleration control, or performs slow deceleration control that gradually decelerates the vehicle compared to the first condition. In this driver assistance system, the threshold for when the traffic signal light is yellow is smaller than the threshold for when the traffic signal light is red.

[0010] In this invention, the control device sets a threshold value for when the traffic signal light is "yellow" to be smaller than the threshold value for when the traffic signal light is "red". Therefore, when the light is "yellow", there is a tendency for the predicted speed to exceed the threshold compared to when the light is "red". In other words, deceleration control becomes more difficult to execute when the light is "yellow" compared to when the light is "red". Therefore, according to this invention, excessive deceleration control can be suppressed in this dilemma zone.

[0011] In one aspect of the present invention, the control device increases the threshold as the time elapsed since the traffic signal recognition device identified the light color as yellow.

[0012] Therefore, when a certain amount of time has elapsed since the predicted speed exceeded the threshold, the likelihood of the speed transitioning to below the threshold increases as the threshold increases. For example, although the control device may not perform deceleration control at the moment it identifies the light color as "yellow" because the predicted speed is above the threshold, the threshold increases along with time. Therefore, as the light color is about to change to "red," the predicted speed will become below the threshold, and deceleration control will begin. This improves the safety of the vehicle.

[0013] In other embodiments of the invention, the control device increases the threshold when the traffic signal light is yellow, the vehicle's direction indicator is active, and the vehicle is entering a dedicated lane for turning in the direction indicated by the direction indicator.

[0014] Accordingly, when the direction indicator indicates "right turn" ("left turn") and the vehicle is in the right turn lane (left turn lane), the control device increases the threshold. Therefore, in this situation, the predicted speed tends to fall below the threshold. This allows the vehicle to decelerate, thus enabling a safe right (left) turn.

[0015] In other embodiments of the invention, the control device increases the threshold when the traffic signal light is yellow, the vehicle's direction indicator is active, and the vehicle is located at one end of the width of the road in which it is traveling, in the direction indicated by the direction indicator.

[0016] Therefore, since the threshold increases when the direction indicator indicates "right turn" ("left turn") and the vehicle is located at the right (left) end of the road, the vehicle tends to fall below the predicted speed. This allows the vehicle to decelerate, thus enabling a safe right (left) turn.

[0017] Furthermore, the driving assistance method and driving assistance program according to the present invention include steps performed by each device constituting the aforementioned driving assistance device. According to the present invention, it is possible to suppress the execution of excessive deceleration control in a dilemma zone. Attached Figure Description

[0018] Figure 1 This is a block diagram of a driving assistance device according to one embodiment of the present invention.

[0019] Figure 2 A graph illustrating an example of the relationship between prediction speed and the threshold.

[0020] Figure 3A This represents the tables in the first database.

[0021] Figure 3B This represents a table in the second database.

[0022] Figure 4 To represent the relationship between and based on Figure 3A as well as Figure 3B The graph shows the calculation formula for the threshold corresponding to the determined likelihood.

[0023] Figure 5 This is a flowchart of the program used to implement deceleration control.

[0024] Figure 6 A graph representing the process of gradually increasing the likelihood (threshold).

[0025] Figure 7 A top view showing an example of changing the target location.

[0026] Figure 8 This represents a table in a third database.

[0027] Figure 9 To indicate the basis Figure 8 The graph shows the calculation formula for the threshold corresponding to the determined likelihood. Detailed Implementation

[0028] (Structure Overview)

[0029] like Figure 1As shown, a driving assistance device 1 according to one embodiment of the present invention is mounted on a vehicle V. As detailed below, the driving assistance device 1 can control the drive system, braking system, etc., of the vehicle V according to the light pattern of the traffic signal S, to perform deceleration control that slows down the vehicle V. Furthermore, to distinguish it from other vehicles, a vehicle equipped with the driving assistance device 1 is sometimes referred to as "this vehicle".

[0030] (Specific structure)

[0031] like Figure 1 As shown, the driving assistance device 1 includes a driving assistance ECU 10, an on-board sensor 20, a drive unit 30, a braking device 40, and a gear shifting device 50.

[0032] The driver assistance ECU 10 includes a microcomputer comprising a CPU 10a, ROM 10b, RAM 10c, and a timer 10d. Furthermore, in this specification, "ECU" refers to an Electronic Control Unit, which includes a microcomputer comprising a CPU (Central Processing Unit), RAM (Random Access Memory), and ROM (Read-Only Memory). The CPU executes instructions stored in the ROM to perform various functions.

[0033] The driver assistance ECU 10 is connected to other ECUs (engine ECU 31, brake ECU 41 and SBW ECU 51 described below) via CAN (Controller Area Network) in a way that allows them to send and receive information to each other.

[0034] The vehicle-mounted sensor 20 includes sensors that acquire information about the vehicle's surroundings, including information about three-dimensional objects present around the vehicle V and information about lane markings on the road surface around the vehicle V. That is, for example, the vehicle-mounted sensor 20 includes sensors that acquire information related to moving objects such as cars (other vehicles), pedestrians, and bicycles, as well as fixed objects such as white lines on the road surface, guardrails, and traffic signals.

[0035] Specifically, the vehicle-mounted sensor 20 includes a radar sensor 21, an ultrasonic sensor 22, a camera 23, and a navigation system 24.

[0036] The radar sensor 21 includes a radar transceiver unit and a signal processing unit (not shown). The radar transceiver unit radiates millimeter-wave radio waves (hereinafter referred to as "millimeter waves") to the area surrounding the vehicle and receives millimeter waves reflected back by objects within the radiation range (i.e., reflected waves). The signal processing unit obtains information such as the distance between the vehicle V and the object, the relative speed between the vehicle V and the object, and the relative position (direction) of the object relative to the vehicle V, based on the phase difference between the transmitted millimeter wave and the received reflected wave, the attenuation level of the reflected wave, and the time from the transmission of the millimeter wave to the reception of the reflected wave, and transmits this information to the driver assistance ECU 10.

[0037] The ultrasonic sensor 22 transmits ultrasonic waves in a pulsed manner to a predetermined range around the vehicle and receives reflected waves that are reflected back by objects. Based on the time from the transmission of the ultrasonic wave to the reception of the reflected wave, the ultrasonic sensor obtains information such as "the reflection point on the object where the transmitted ultrasonic wave was reflected" and "the distance between the ultrasonic sensor and the object", and transmits this information to the driver assistance ECU 10.

[0038] Camera 23 includes an image capturing device and an image analysis device. The image capturing device is, for example, a digital camera with a built-in CCD (charge-coupled device) or CIS (CMOS image sensor) image capturing element. The image capturing device is positioned at the upper part of the windshield. The image capturing device captures image data of the foreground of the vehicle at a predetermined frame rate and outputs it to the image analysis device. The image analysis device analyzes the acquired image data and extracts information related to objects located in front of the vehicle V from the image, and sends it to the driver assistance ECU 10. For example, the image analysis device attempts to identify the light pattern (the light color of the tri-color light device and the on / off state of the arrow light device indicating the direction of travel) of the nearest traffic signal S located in front of the vehicle V in the direction of travel. When the image analysis device can identify the light pattern of the traffic signal S, it sends the data representing the light pattern as traffic signal identification data to the driver assistance ECU 10. Furthermore, if the light pattern of traffic signal S cannot be identified, the image analysis device sends data indicating "unrecognizable" to the driver assistance ECU 10 as traffic signal identification data, as the identification result. In addition, the image analysis device identifies the lane division (e.g., right-turn lane, left-turn lane, etc.) of the lane in which the vehicle is traveling based on images of road white lines (lane lines, stop lines, etc.), and sends information indicating the identification result to the driver assistance ECU 10.

[0039] The navigation system 24 receives GPS signals from multiple satellites and detects the current position (latitude and longitude) of the vehicle V based on the received GPS signals. Furthermore, the navigation system 24 stores map data representing a map. The map data includes road information representing roads and traffic signal location information representing the locations of traffic signals. The navigation system 24 sends the vehicle position information, representing the detected current position, to the driver assistance ECU 10. Additionally, the navigation system 24 has the function of calculating the distance (distance along a road) between two locations. For example, the navigation system 24 can calculate the distance L from the current position of the vehicle V to the nearest traffic signal S (the first traffic signal passed when traveling straight along the lane the vehicle V is currently traveling in) and send this distance data to the driver assistance ECU 10.

[0040] The vehicle sensor 20 also includes sensors that acquire information related to the driving state of the vehicle V (speed, acceleration, operating mode of operating elements, etc.).

[0041] Specifically, the vehicle-mounted sensor 20 includes a speed sensor 25, an acceleration sensor 26, an accelerator pedal sensor 27, a brake pedal sensor 28, and a gear shift lever sensor 29.

[0042] Speed ​​sensor 25 includes a wheel speed sensor that generates a pulse signal (wheel pulse signal) whenever a wheel of the vehicle rotates a predetermined angle. Speed ​​sensor 25 measures the number of pulses per unit time of the wheel pulse signal sent from the wheel speed sensor, calculates the rotational speed (wheel speed) of each wheel based on the measured number of pulses, and calculates the vehicle speed vs (actual vehicle speed) based on the wheel speed of each wheel. Speed ​​sensor 25 sends the data representing speed vs to driver assistance ECU 10.

[0043] Accelerometer 26 detects the acceleration Ga acting on the vehicle V (e.g., acceleration in the width direction of the vehicle V when driving on a curved road, acceleration in the longitudinal direction of the vehicle V when driving on a straight road, etc.). Accelerometer 26 sends data representing the acceleration Ga to driver assistance ECU 10.

[0044] Accelerator pedal sensor 27 detects the depth AD of the accelerator pedal (not shown) of vehicle V. Accelerator pedal sensor 27 sends data representing the depth AD of the accelerator pedal to driver assistance ECU 10.

[0045] Brake pedal sensor 28 detects the depth BD of the brake pedal (not shown) of vehicle V. Brake pedal sensor 28 sends data representing the depth BD of the brake pedal to driver assistance ECU 10.

[0046] The shift lever sensor 29 detects the position (shift lever position SP) of the shift lever (not shown) of the vehicle V. The shift lever sensor 29 sends the data indicating the shift lever position SP to the driver assistance ECU 10.

[0047] In addition, the vehicle sensor 20 includes a switch (turn indicator sensor 2a) for detecting the operating status of various switches on the vehicle V (e.g., the turn indicator lever).

[0048] The drive unit 30 generates driving force and applies it to the drive wheels (left front wheel, right front wheel, left rear wheel, and right rear wheel). The drive unit 30 includes an engine ECU 31, an engine actuator 32, an internal combustion engine 33, a transmission 34, and a drive force transmission mechanism (not shown) that transmits driving force to the wheels. The engine ECU 31 is connected to the engine actuator 32. The engine actuator 32 includes a throttle actuator that changes the opening of the throttle valve of the internal combustion engine 33. The engine ECU 31 obtains the accelerator pedal depth AD from the driver assistance ECU 10. Furthermore, the driver assistance ECU 10 can appropriately correct the accelerator pedal depth AD obtained from the accelerator pedal sensor 27 and send it to the engine ECU 31. The engine ECU 31 drives the engine actuator 32 according to the accelerator pedal depth AD obtained from the driver assistance ECU 10. In this way, the torque generated by the internal combustion engine 33 is controlled. The torque generated by the internal combustion engine 33 is transmitted to the drive wheels via the transmission 34 and the drive force transmission mechanism (e.g., drive shaft).

[0049] Furthermore, when the vehicle V using driver assistance device 1 is a hybrid electric vehicle (HEV), the engine ECU 31 can control the driving force of the vehicle generated by either or both of the "internal combustion engine and electric motor" that serve as the vehicle's driving source. Moreover, when the vehicle V using driver assistance device 1 is a battery electric vehicle (BEV), only an electric motor ECU is needed instead of the engine ECU 31 to control the driving force of the vehicle generated by the "electric motor" that serves as the vehicle's driving source.

[0050] Braking device 40 applies braking force to the wheels. Braking device 40 includes brake ECU 41, hydraulic circuit 42, and brake caliper 43. Hydraulic circuit 42 includes a reservoir (not shown), oil pump, various valve devices, hydraulic sensors, etc. Brake caliper 43 is a hydraulic actuator with a hydraulic cylinder and piston. When oil is supplied to the hydraulic cylinder, the piston is pushed out of the hydraulic cylinder. A brake block is provided at the top of the piston, which pushes against the brake disc, thereby increasing the braking pressure. Brake ECU 41 obtains the brake pedal depth BD from driver assistance ECU 10. In addition, driver assistance ECU 10 can appropriately correct the pedal depth BD obtained from brake pedal sensor 28 and send it to brake ECU 41. Brake ECU 41 sends hydraulic control commands to hydraulic circuit 42 according to the pedal depth BD obtained from driver assistance ECU 10. Hydraulic circuit 42 adjusts the hydraulic pressure in the hydraulic cylinder of brake caliper 43 according to the hydraulic control commands obtained from brake ECU 41. In this way, the braking force of the wheel (brake disc) generated by the brake caliper 43 is controlled.

[0051] The shift-by-wire device 50 switches the shift positions of the transmission 34. The shift-by-wire device 50 includes an SBW (Shift-by-Wire) ECU 51, an SBW actuator 52, and a shift-by-wire mechanism 53. The SBW ECU 51 is connected to the SBW actuator 52. The SBW ECU 51 obtains the shift lever position SP from the driver assistance ECU 10. Furthermore, the driver assistance ECU 10 can appropriately correct the shift lever position SP obtained from the shift lever sensor 29 and send it to the SBW ECU 51. The SBW ECU 51 sends a shift-by-wire command to the SBW actuator 52 based on the shift lever position SP obtained from the driver assistance ECU 10. The SBW actuator 52 controls the shift-by-wire mechanism 53 based on the shift-by-wire command obtained from the SBW ECU 51. In this way, the shift positions of the transmission 34 are switched.

[0052] (Work)

[0053] As explained below, the driver assistance ECU10 determines whether to perform deceleration control (deceleration assist) to slow down the vehicle based on the situation.

[0054] <Deceleration Control>

[0055] The driver assistance ECU 10 sequentially acquires traffic signal recognition data from the camera 23. When the driver assistance ECU 10 identifies the light color (light color of the tri-color light device) as one of the light patterns of the traffic signal S as represented by the traffic signal recognition data as "green", or when the light color of the traffic signal S is unclear, the driver assistance ECU 10 does not perform deceleration control (deceleration assist).

[0056] On the other hand, when the light color of traffic signal S, as indicated by traffic signal identification data, is "yellow or red", the driver assistance ECU 10 decides whether to perform deceleration control in the following manner.

[0057] Here, situation A can be considered as the driver's intention to slow down the vehicle.

[0058] (Situation A) The depth of the brake pedal BD increases.

[0059] On the other hand, situation B below can be considered as a situation where the driver wants to accelerate the vehicle.

[0060] (Situation B) The accelerator pedal depth AD increases or becomes a fixed value greater than "0".

[0061] Other situations C (e.g., when the pedal depth AD and pedal depth BD are "0") can be considered as situations where it is unclear whether the driver intends to accelerate or decelerate the vehicle.

[0062] The driver assistance ECU 10 successively acquires the pressing depth of the accelerator pedal and brake pedal, and detects changes in these data. Then, based on the detection results, the driver assistance ECU 10 determines which of the above conditions A to C the current situation belongs to.

[0063] If the current situation meets either condition A or condition C, the driver assistance ECU 10 obtains the distance LS to the traffic signal S from the navigation system 24. Next, the driver assistance ECU 10 determines the location where the traffic signal S is set (e.g., a location closer to the stop line than the traffic signal S) as the target location sp. Next, the driver assistance ECU 10 obtains the vehicle's current speed vs from the speed sensor 25. Then, the driver assistance ECU 10 calculates the vehicle's speed (hereinafter referred to as "predicted speed vp") at the point in time when the vehicle reaches the target location sp, assuming the vehicle decelerates from the current speed vs at a predetermined deceleration a (an acceleration in the opposite direction of the vehicle's travel direction (a fixed value)).

[0064] When the predicted velocity vp is less than the threshold vpth described later (refer to...) Figure 2 The driver assistance ECU 10 performs deceleration control. That is, the driver assistance ECU 10 controls the drive unit 30, braking unit 40, and shift switching device 50 (hereinafter referred to as "drive units, etc.") in a manner that makes the deceleration consistent with a predetermined value, thereby decelerating the vehicle. Furthermore, the deceleration in this deceleration control can be the same as or different from the deceleration 'a' used when calculating the predicted speed 'vp'. Moreover, if the predicted speed 'vp' is higher than or equal to a threshold 'vpth', the driver assistance ECU 10 does not perform deceleration control.

[0065] The threshold vpth is determined based on the likelihood (hereinafter referred to as "likelihood LH") of causing the vehicle to decelerate from its current position. Here, the likelihood LH is determined based on a pre-defined database DB that establishes a correspondence between the traffic signal S's light pattern and the vehicle's position (lane division or position in the width direction of the lane). This database DB is stored in ROM10b.

[0066] Database DB is in Figure 3A as well as Figure 3B The system is configured with a first database DB1 and a second database DB2, as shown below. The first database DB1 is the same as the database in the existing device described above. The second database DB2 is used when the traffic signal S is yellow.

[0067] The driver assistance ECU10 first refers to the first database DB1 and temporarily determines the likelihood LH corresponding to the light pattern of the traffic signal S.

[0068] Next, when the traffic signal S is yellow, the driver assistance ECU 10 corrects the likelihood LH, which was temporarily determined in the above manner, based on the second database DB2. Conversely, when the traffic signal S is red, the driver assistance ECU 10 does not correct the likelihood LH. In other words, the driver assistance ECU 10 uses the temporarily determined likelihood LH to calculate the threshold vpth.

[0069] For example, when the traffic signal S is yellow and no arrow light is installed, the likelihood LH is first set (temporarily determined) to "H2" based on the first database DB1. Next, "α" is subtracted from the likelihood LH ("-α" is added to the likelihood LH) based on the second database DB2. That is, in this case, the likelihood LH is first temporarily determined to be "H2", and then corrected to "H2-α". Furthermore, for example, when the direction indicator (turn signal) indicates the direction of travel of the vehicle (e.g., the direction indicator indicates left and the vehicle is in the left turn lane), or when the vehicle is located at the end of the width direction of the lane and at the end of the direction indicated by the direction indicator (e.g., the direction indicator indicates left and the vehicle is at the left end of the width direction of the lane), the likelihood LH is corrected to "H2-α+β". Here, "α" (absolute value) is greater than "β" (absolute value).

[0070] Furthermore, as the time Δt elapsed since the traffic signal S was identified as having a "yellow" light color increases, the driver assistance ECU 10 gradually increases the likelihood LH. However, the maximum value at which the likelihood LH increases with time Δt is less than "H2".

[0071] Next, the driver assistance ECU 10 applies the likelihood LH, determined based on the database DB, to (substitute) the predetermined formula E[LH] to determine the threshold vpth. Additionally, as... Figure 4 As shown, the operation formula E[LH] is determined by the principle that the higher the likelihood LH, the higher the threshold vpth.

[0072] Thus, the driver assistance ECU 10 determines the threshold vpth in such a way that the threshold vpth when the traffic signal S is yellow is decreased by α compared to the threshold vpth when the traffic signal S is red. Furthermore, as the time elapsed since the yellow light color was detected increases, the driver assistance ECU 10 increases the threshold vpth determined when the traffic signal S is yellow. Additionally, the driver assistance ECU 10 increases the threshold vpth by β when the traffic signal is yellow, the vehicle's turn indicator is active, and the vehicle is entering a dedicated lane for turning in the direction indicated by the turn indicator. Moreover, the driver assistance ECU 10 increases the threshold vpth by β when the traffic signal is yellow, the vehicle's turn indicator is active, and the vehicle is located at the end of the direction indicated by the turn indicator at one end of the width direction of the road in which the vehicle is traveling. Furthermore, the threshold vpth that is corrected when the traffic signal S is in "yellow" will not exceed the threshold vpth when the traffic signal S is in "red".

[0073] Next, refer to Figure 5 The operation of the CPU 10a (hereinafter referred to as "CPU") of the aforementioned driver assistance ECU 10 (for executing the deceleration control program P1) will be explained. The CPU sequentially acquires traffic signal recognition data from the camera 23. Furthermore, if the traffic signal recognition data indicates the light pattern of the traffic signal S, the CPU executes program P1. On the other hand, if the traffic signal recognition data indicates "light pattern not recognized," the CPU does not execute program P1.

[0074] (Program P1)

[0075] The CPU starts executing program P1 from step 100 and proceeds to step 101.

[0076] When the CPU proceeds to step 101, it determines whether the light color of traffic signal S is "red or yellow" based on the traffic signal recognition data. If the light color of traffic signal S is "red or yellow" (101: Yes), the CPU proceeds to step 102. On the other hand, if the light color of traffic signal S is "green" (101: No), the CPU proceeds to step 111, which will be described later.

[0077] When the CPU proceeds to step 102, it determines whether the current situation (the situation related to the operation of the accelerator pedal and brake pedal) conforms to either situation A or situation C as described above. If the operation of the accelerator pedal and brake pedal conforms to either situation A or situation C (102: Yes), the CPU proceeds to step 103. On the other hand, if the operation of the accelerator pedal and brake pedal conforms to situation B as described above (102: No), the CPU proceeds to step 111.

[0078] When the CPU proceeds to step 103, it calculates the predicted velocity vp. Specifically, the CPU obtains the velocity vs. . Furthermore, the CPU determines the target position sp and obtains the distance L from the current position to the target position sp from the navigation system 24. Then, the CPU calculates the predicted velocity vp based on the velocity vs, the distance L, and the deceleration a. Then, the CPU proceeds to step 104.

[0079] When the CPU proceeds to step 104, it refers to the first database DB1 and temporarily determines the likelihood LH based on whether the arrow light device is set and whether the movement is possible, and then proceeds to step 105.

[0080] When the CPU proceeds to step 105, it determines whether the traffic signal S light is "yellow". If the light is "yellow" (105: Yes), the CPU proceeds to step 106. On the other hand, if the light is not "yellow" (it is "red" (105: No)), the CPU proceeds to step 108.

[0081] When the CPU proceeds to step 106, it corrects the likelihood LH by referring to the second database DB2. Specifically, in step 106, the CPU corrects the likelihood LH by subtracting a correction value α from the likelihood LH. Next, it determines whether the direction indicator is working. If the direction indicator is working, it determines whether the direction indicated by the vehicle's direction indicator matches the vehicle's driving lane, and whether the vehicle is located at the end of the width of the driving lane and at the end of the direction indicated by the direction indicator. Furthermore, if the above determination result is "yes", the likelihood LH is further corrected by adding a correction value β to the corrected likelihood LH. After that, the CPU proceeds to step 107.

[0082] When the CPU proceeds to step 107, it further corrects the likelihood LH by adding the likelihood LH to the correction value corresponding to the elapsed time since the traffic signal S was identified as having a "yellow" light color. Then, the CPU proceeds to step 108.

[0083] When the CPU proceeds to step 108, it applies the likelihood LH to the expression E to calculate the threshold vpth, and then proceeds to step 109.

[0084] When the CPU proceeds to step 109, it determines whether the predicted speed vp is less than the threshold vpth. If the predicted speed vp is less than the threshold vpth (109: Yes), the CPU proceeds to step 110. On the other hand, if the predicted speed vp is greater than or equal to the threshold vpth (109: No), the CPU proceeds to step 111.

[0085] When the CPU proceeds to step 110, it performs deceleration control. For example, the CPU controls the braking device 40 to increase the braking pressure within a predetermined short time (the time for executing step 110). Afterward, the CPU proceeds to step 112 and terminates the execution of program P1.

[0086] Furthermore, if the CPU proceeds to step 111, it proceeds to step 112 without performing deceleration control.

[0087] The aforementioned procedure P1 is executed at predetermined intervals (every predetermined short period of time). That is, during the period when the vehicle is approaching the traffic signal S, procedure P1 is executed repeatedly. Moreover, during this period, the predicted speed vp and the threshold vpth may change depending on the operation of the accelerator and brake pedals, changes in the light pattern of the traffic signal S, etc.

[0088] (Effect)

[0089] The CPU executes program P1 as described above, thereby performing deceleration control when the predicted speed vp is less than the threshold vpth, and not performing deceleration control when the predicted speed vp is greater than or equal to the threshold vpth. Furthermore, the CPU sets the likelihood LH (threshold vpth) for the traffic signal S when the light color is "yellow" to be smaller than the likelihood LH (threshold vpth) for the traffic signal S when the light color is "red". Therefore, compared to the case of "red" light color, the case of "yellow" light color tends to result in the predicted speed vp exceeding the threshold vpth. In other words, deceleration control becomes more difficult to execute when the light color is "yellow" light color compared to the case of "red" light color. Therefore, according to this embodiment, excessive deceleration control execution can be suppressed in the dilemma region.

[0090] Additionally, the CPU gradually increases the likelihood LH (threshold vpth) starting from time point t1 (position p1) when the light color is identified as "yellow". For example, in Figure 6In the example shown, after a certain amount of time has elapsed since the predicted speed vp exceeds the threshold vpth (time point t1), the state transitions to a state where the predicted speed vp is less than the threshold vpth (time point t2). In this case, although no deceleration control is performed at time point t1 when the light color is identified as "yellow," deceleration control is performed at time point t2 (position p2), when the light color is about to change to "red." Therefore, since deceleration control begins slightly before the traffic signal S's light color changes to "red," vehicle safety can be further improved. Furthermore, although the predicted speed vp is set to constant in the example shown for simplicity, there are also cases where the predicted speed vp changes as the vehicle approaches the traffic signal S.

[0091] Furthermore, when the direction indicator indicates "right turn" ("left turn") and the vehicle is located in the right turn lane (left turn lane) or at the right end (left end) of the lane, the CPU increases the likelihood LH (threshold vpth). Therefore, the predicted speed vp tends to become less than the threshold vpth. Consequently, the vehicle is decelerated, allowing the driver to safely make a right (left) turn.

[0092] The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the present invention as described below.

[0093] <Change Example 1>

[0094] As described above, the CPU pre-determines the likelihood LH by referring to the first database DB1, and subtracts a correction value from the likelihood LH when the light color is "yellow". In this case, the correction value for the traffic signal S changing from "green" to "yellow" (the first correction value) can be different from the correction value for the traffic signal S changing from "red" and the arrow light device being lit to "yellow" (the second correction value). For example, the first correction value can be greater than the second correction value.

[0095] <Change Example 2>

[0096] like Figure 7 As shown, the CPU can also be configured to set the target position sp as the stop line near the traffic signal S (intersection) as a rule. However, the CPU can also shift the target position sp forward (within the intersection) at the point when it recognizes that the vehicle has entered the right-turn lane (left-turn lane) based on information obtained from the on-board sensor 20.

[0097] <Change Example 3>

[0098] In the above embodiment, the database DB consists of a first database DB1 used to temporarily determine the likelihood LH when the traffic signal S light color is "red or yellow", and a second database DB2 used to correct the likelihood LH when the traffic signal S light color is "yellow". Alternatively, a third database DB3 (see above) can be used, which includes multiple likelihood LHs corresponding to multiple types of light color "red" and multiple likelihood LHs corresponding to multiple types of light color "yellow". Figure 8 Accordingly, the CPU can refer to the third database DB3 to obtain the likelihood LH corresponding to the light pattern of the traffic signal S. In other words, compared to temporarily determining the likelihood LH and correcting for it, the process of determining the likelihood LH is simplified. Furthermore, in this case, using... Figure 9 The expression shown is used to calculate the threshold vpth.

[0099] <Change Example 4>

[0100] Although Figure 8 The third database DB3, as shown, specifies the relationship between the light pattern of traffic signal S and the likelihood LH. However, a fourth database DB4, which specifies the relationship between the light pattern of traffic signal S and the threshold vpth, can be used instead. Accordingly, the CPU can directly obtain the threshold vpth corresponding to the light pattern of traffic signal S by referring to the fourth database DB4. In other words, compared to the case where the CPU refers to the third database DB3 to determine the likelihood LH and applies that likelihood LH to the calculation E to determine the threshold vpth, the process of determining the threshold vpth is simplified.

[0101] <Change Example 5>

[0102] Although the above implementation method adopts the approach of not performing deceleration control when the predicted speed vp is above the threshold vpth, it is also possible to perform a slow deceleration control that decelerates the vehicle more slowly (more slowly than when the predicted speed vp is below the threshold vpth) when the predicted speed vp is above the threshold vpth.

Claims

1. A driving assist device that is mounted on a host vehicle and that includes: traffic signal recognizer means that recognizes a light form of a traffic signal present in front of the host vehicle; control means that, in a case where the light form of the traffic signal recognized by the traffic signal recognizer means is a predetermined form, determines a predetermined position in the vicinity of the traffic signal as a target position, and executes deceleration control that decelerates the host vehicle until the host vehicle reaches the target position, and that is configured to calculate a predicted speed that is a speed of the host vehicle at a time point at which the host vehicle reaches the target position in a case where the host vehicle is decelerated at a predetermined deceleration form from a current time point, and to execute the deceleration control in a first condition where the predicted speed is less than a threshold value determined based on the light form of the traffic signal, and not to execute the deceleration control or to execute slow deceleration control that decelerates the host vehicle more slowly than in the first condition in a second condition where the predicted speed is equal to or greater than the threshold value, in the driving assist device, the threshold value in a case where a light color of the traffic signal is yellow is smaller than the threshold value in a case where the light color of the traffic signal is red.

2. The driving assist device according to claim 1, wherein the control means increases the threshold value as an elapsed time from a time point at which the light color is recognized by the traffic signal recognizer means as yellow increases.

3. The driving assist device according to claim 1 or claim 2, wherein the control means increases the threshold value in a condition where the light color of the traffic signal is yellow, a turn signal of the host vehicle is operating, and the host vehicle is entering a lane dedicated for turning in a direction indicated by the turn signal.

4. The driving assist device according to claim 1 or claim 2, wherein the control means increases the threshold value in a condition where the light color of the traffic signal is yellow, a turn signal of the host vehicle is operating, and the host vehicle is positioned at an end portion of the direction indicated by the turn signal in a width direction of a road on which the host vehicle is traveling.

5. A driving assist method that is applied to a host vehicle and that includes: a signal recognition step of recognizing a light form of a traffic signal present in front of the host vehicle; ​ ​ ​ The control step decides a predetermined position in the vicinity of the traffic signal as a target position in a case where the light pattern of the traffic signal recognized in the signal recognition step is a predetermined pattern, and executes deceleration control that decelerates the host vehicle until the host vehicle reaches the target position, and calculates a predicted speed that is the speed of the host vehicle at a time point at which the host vehicle reaches the target position in a case where the host vehicle is decelerated at a predetermined deceleration pattern from a current time point, and executes the deceleration control in a first condition where the predicted speed is less than a threshold value decided based on the light pattern of the traffic signal, and does not execute the deceleration control or executes slow deceleration control that decelerates the host vehicle more slowly than in the first condition in a second condition where the predicted speed is the threshold value or more, In the driving assistance method, The threshold value in a case where the light color of the traffic signal is yellow is smaller than the threshold value in a case where the light color of the traffic signal is red.

6. A storage medium including a driving assistance program that causes a computer possessed by a host vehicle to execute the steps of: a signal recognition step that recognizes a light pattern of a traffic signal present in front of the host vehicle; a control step that decides a predetermined position in the vicinity of the traffic signal as a target position in a case where the light pattern of the traffic signal recognized in the signal recognition step is a predetermined pattern, and executes deceleration control that decelerates the host vehicle until the host vehicle reaches the target position, and calculates a predicted speed that is the speed of the host vehicle at a time point at which the host vehicle reaches the target position in a case where the host vehicle is decelerated at a predetermined deceleration pattern from a current time point, and executes the deceleration control in a first condition where the predicted speed is less than a threshold value decided based on the light pattern of the traffic signal, and does not execute the deceleration control or executes slow deceleration control that decelerates the host vehicle more slowly than in the first condition in a second condition where the predicted speed is the threshold value or more, In the storage medium, The threshold value in a case where the light color of the traffic signal is yellow is smaller than the threshold value in a case where the light color of the traffic signal is red.

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