Vehicle Driving Assistance Device

Abstract

To provide a vehicle operation support apparatus with a practicality configured.SOLUTION: A control apparatus performs: estimating a recognizable distance Da0 in a case where a recognizable distance Da being a distance to a target at a farthest distance recognizable by a surroundings recognition sensor is in correlation with either one or both of a weather condition and a luminous intensity on outside of a vehicle, and further estimating a recognizable distance Db0 being a distance to a target at farthest distance recognizable by a driver; executing a first operation support in a case where the recognizable distance Da0 is equal to or more than a necessary distance Dn[VL0] being a distance necessary to execute the first operation support, executing a second operation support in a case where the recognizable distance Da0 is shorter than the necessary distance Dn[VL0] and equal to or more than the recognizable distance Db0, or executing no control that causes the vehicle itself to travel autonomously in a case where the recognizable distance Da0 is shorter than both the necessary distance and recognizable distance Db.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a vehicle driving assistance device that assists a driver of a vehicle in driving a vehicle. [Background technology]

[0002] There is known a vehicle driving assistance device (hereinafter referred to as "conventional device") that assists the driver of a vehicle in driving operations (see, for example, Patent Document 1 below). The conventional device includes a surrounding recognition system (e.g., a camera device) that recognizes targets around the vehicle, and a control device that controls the vehicle based on the recognition results of the surrounding recognition system. For example, the control device causes the vehicle to travel autonomously so that the actual speed of the vehicle does not exceed a predetermined value.

[0003] Incidentally, the distance from the vehicle to the farthest target that can be recognized by the surrounding recognition system (e.g., a camera device) (hereinafter referred to as the "system recognizable distance") may correlate with weather conditions, brightness (illuminance) outside the vehicle, etc. Specifically, the recognizable distance of the camera device tends to be shorter when it is raining or snowing, or when there is fog, compared to when the weather is fine. Also, for example, the recognizable distance of the camera device tends to be shorter at night when the illuminance is low, compared to when the illuminance is high during the day.

[0004] In order for the control device to execute driving assistance (e.g., autonomous driving control), the system recognizable distance needs to be equal to or greater than a predetermined value (the lower limit for executing that driving assistance). Hereinafter, this predetermined value is referred to as the "required distance." For example, the required distance for the control device to execute driving assistance to autonomously drive the vehicle at "100 km / h" is "190 m." Also, for example, the required distance for the control device to execute driving assistance to autonomously drive the vehicle at "50 km / h" is "100 m."

[0005] For example, when the control device performs driving assistance to autonomously drive the vehicle so as not to exceed the legal speed limit of the road, the control device estimates the current system recognizable distance. The control device then determines whether the estimated result is equal to or greater than a required distance predefined for the driving assistance. If the estimated system recognizable distance is equal to or greater than the required distance, the control device performs the driving assistance. In this case, the main driver of the vehicle is the control device.

[0006] On the other hand, if the estimated system recognizable distance is shorter than the required distance, the driving assistance mode is degraded. For example, the control device sets the upper limit of the vehicle speed to a predetermined value that is lower than the legal speed limit, and causes the vehicle to drive autonomously. In this case, too, the main driver of the vehicle is the control device.

[0007] If the estimated system recognizable distance is significantly small (smaller than a predetermined threshold), the control device stops controlling the vehicle to drive autonomously. That is, in this case, the driver (passenger) of the vehicle must perform driving operations. In this case, the control device does not perform advanced driving assistance such as driving the vehicle autonomously, but may perform assistance to assist the driver's driving operations (for example, providing position information of detected targets). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2020-082855 A Summary of the Invention

[0009] Incidentally, the distance to the farthest target that the driver can recognize (hereinafter referred to as the "driver recognizable distance") also correlates with weather conditions, illuminance, and the like. The driver recognizable distance may be equal to or greater than the system recognizable distance, or may be smaller than the system recognizable distance. In the conventional device, the magnitude relationship between the system recognizable distance and the driver recognizable distance is not taken into consideration. Therefore, when the conventional device is adopted, the control device may execute a driving operation even if it is actually a situation in which it is preferable for the driver to execute a driving operation (driver recognizable distance > system recognizable distance). Conversely, the driver may have to execute a driving operation even if it is a situation in which it is preferable for the control device to execute a driving operation (system recognizable distance > driver recognizable distance). As described above, in the conventional device, either the control device or the driver (passenger) is selected (determined) as the subject of the vehicle driving operation, but the selection result may not be in accordance with the actual situation (the magnitude relationship between the system recognizable distance and the driver recognizable distance). Therefore, the practicality of the conventional device is low.

[0010] An object of the present invention is to provide a vehicle driving assistance device with improved practicality.

[0011] In order to solve the above problems, the vehicle driving assistance device (1) of the present invention comprises: A surrounding recognition system (10) that recognizes targets around a host vehicle (V); a sensor for detecting a current speed of the host vehicle; The recognition result of the surrounding recognition system and information obtained from said sensor. A control device (50) that controls the host vehicle based on the Equipped with. The control device includes: When a system recognizable distance (Da), which is a distance to the farthest target that the surrounding recognition system can recognize, correlates with either or both of the weather condition (R) and the illuminance (B) outside the vehicle, the system recognizable distance (Da0) is estimated, and further Vehicle Estimate the driver recognizable distance (Db0), which is the distance to the farthest target that the driver can recognize; The estimated system recognizable distance (Da0) is A vehicle driver may set the vehicle ID in advance. Speed The current speed of the vehicle is Do not exceed Controlling the drive device and / or the brake device of the host vehicle A distance required to execute a first driving assistance for autonomously driving the host vehicle. and the braking distance is greater than the braking distance corresponding to the current speed of the vehicle. If the distance is equal to or greater than the prescribed required distance (Dn[VL0]), the first driving assistance is executed; When the estimated system recognizable distance is smaller than the required distance and is equal to or larger than the estimated driver recognizable distance, a speed (VL[Da0]) corresponding to the system recognizable distance is calculated. The current speed of the vehicle is Do not exceed Controlling the drive device and / or the brake device of the host vehicle Execute a second driving assistance to cause the host vehicle to travel autonomously; When the estimated system recognizable distance is shorter than the necessary distance and shorter than the estimated driver recognizable distance, control for causing the host vehicle to travel autonomously is not executed.

[0012] As described above, when the surroundings recognition system can recognize targets farther away than the driver, the control device takes the lead in driving the vehicle. Conversely, when the driver (passenger) can recognize targets farther away than the surroundings recognition system, the control device stops controlling the vehicle to travel autonomously, and the driver (passenger) takes the lead in driving the vehicle V. Therefore, the vehicle driving assistance device is more practical than conventional devices.

[0013] In one aspect of the present invention, there is provided a vehicle driving assistance device, When the estimated system recognizable distance is smaller than the required distance and smaller than the estimated driver recognizable distance, the control device executes driving assistance to assist the driver's driving operation.

[0014] This improves safety compared to a case in which the driving assistance is not performed.

[0015] In a vehicle driving assistance device according to another aspect of the present invention, The control device includes: The current driver recognizable distance is determined by referring to a lookup table (M2) that specifies the relationship between the weather and / or the illuminance outside the vehicle and the standard value of the driver recognizable distance.

[0016] This makes it easier to determine the driver recognizable distance than, for example, observing the driver using a camera that photographs the interior of the vehicle and determining the driver recognizable distance based on the observation results.

[0017] In a vehicle driving assistance device according to another aspect of the present invention, The control device includes: a vehicle distance between the vehicle and a preceding vehicle when a driver of the vehicle starts to depress a brake pedal while the vehicle is following the preceding vehicle, and a subsequent deceleration and deceleration jerk of the vehicle are stored as feature data, and when an average value of the vehicle distance as the feature data is smaller than a standard value of the vehicle distance and each average value of the deceleration and the deceleration jerk as the feature data is larger than a standard value of the deceleration and the deceleration jerk, the lookup table is corrected by subtracting a predetermined value or a value determined according to a difference between the standard value and the average value from each driver recognizable distance constituting the lookup table, The corrected lookup table is referenced to determine the current driver recognizable distance.

[0018] According to this, the driver's recognition ability (personality) is reflected in the lookup table, so that the practicality of the vehicle driving assistance device is further improved. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a block diagram of a vehicle driving assistance device according to an embodiment of the present invention. [Figure 2A] FIG. 2A is a graph of a map that defines the relationship between the upper limit speed and the required distance. [Figure 2B] FIG. 2B is a graph of a map that defines the relationship between rainfall and illuminance and the driver's recognizable distance. [Diagram 3] FIG. 3 is a diagram showing the magnitude relationship between the recognizable distance of the periphery recognition system, the recognizable distance of the driver, and the required distance. [Figure 4] FIG. 4 is a diagram showing a process of determining a required distance and an upper limit speed according to the map shown in FIG. 2A. [Diagram 5] FIG. 5 is a flowchart of the driving assistance program. [Figure 6]FIG. 6 is a diagram showing an example in which one of a camera device and a radar device is preferentially (selectively) used according to a first modified example of the present invention. [Figure 7] FIG. 7 is a graph of a map defining the relationship between the upper limit speed and the amount of precipitation, and the required distance, according to a second modified example of the present invention. [Figure 8] FIG. 8 is a diagram showing an example of a process for estimating the distance between the vehicle and the preceding vehicle at the timing when the driver actually recognizes the preceding vehicle, according to the third modified example of the present invention. [Figure 9] FIG. 9 is a graph showing the process of correcting the map shown in FIG. 2B. [Figure 10] FIG. 10 is a diagram showing another example of the process of estimating the distance between the vehicle and the preceding vehicle at the timing when the driver actually recognizes the preceding vehicle, according to the third modified example of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] (Summary) As shown in FIG. 1, a vehicle driving assistance device 1 according to an embodiment of the present invention is mounted on a vehicle V. The vehicle driving assistance device 1 executes driving assistance to assist the driving operation of the driver of the vehicle V based on information acquired from an on-board sensor (surrounding recognition system 10), as will be described in detail later. For example, the vehicle driving assistance device 1 controls the engine, brakes, and steering device of the vehicle V (host vehicle) to autonomously drive the vehicle V toward a destination specified by the driver. In addition, for example, the vehicle driving assistance device 1 assists the driving operation by the driver. For example, the vehicle driving assistance device 1 presents information (images, sounds, etc.) representing targets around the vehicle V to the driver.

[0021] (Specific configuration) The vehicle driving assistance device 1 includes a surrounding recognition system 10. The surrounding recognition system 10 includes a camera device 11, a rain sensor 12, and an illuminance sensor 13.

[0022] The camera device 11 is disposed on the upper part of the front windshield glass. The camera device 11 photographs the view in front of the vehicle V. The camera device 11 analyzes the photographed image (image data) of the view in front of the vehicle V (for example, using a well-known pattern recognition technique) to obtain "target information (distance to a target (for example, a preceding vehicle), a target direction, etc.)", "lane information (information on a dividing line (white line) that divides the lane in which the vehicle V is traveling, information on road signs, etc.)", "environmental information (weather conditions (rain, snow, fog, etc.), illuminance, backlight, etc.)", etc. These pieces of information are supplied to the driving assistance ECU 50 described later. Note that, in this embodiment, "amount of rainfall" is used as an index indicating whether the weather conditions are good or bad, but "amount of snowfall", "density of fog", etc. may be used as an index indicating whether the weather conditions are good or bad.

[0023] The rain sensor 12 detects the current amount of rainfall. For example, the rain sensor 12 may include an LED, which is an infrared emitting element, a photodiode, which is a light receiving element, and a lens that forms an optical path for the infrared rays. The infrared rays emitted from the LED to the outside of the vehicle from the passenger compartment side are totally reflected by the windshield glass. However, if water droplets are present on the outer surface of the windshield glass, part of the infrared rays penetrates the water droplets and is emitted to the outside, so the amount of reflection decreases. As a result, the amount of light received by the photodiode, which is a light receiving element, decreases. Therefore, the amount of rainfall can be detected based on the decrease in the amount of received light. Then, information indicating the amount of rainfall is supplied to the driving assistance ECU 50, which will be described later. In addition, a wiper controller (not shown) changes the speed of the reciprocating motion of the wiper arm according to the detection result of the rain sensor 12.

[0024] The illuminance sensor 13 detects the current illuminance outside the vehicle. A configuration including a photodiode can be adopted as the illuminance sensor 13. Then, information indicating the illuminance is supplied to a driving assistance ECU 50, which will be described later. Also, a headlight controller (not shown) switches the on / off state (on / off) of the headlights according to the detection result of the illuminance sensor 13.

[0025] Furthermore, the vehicle driving assistance device 1 includes an engine ECU 20, a brake ECU 30, a steering ECU 40, and a driving assistance ECU (hereinafter referred to as a "DAECU") 50. These ECUs are connected to each other via a controller area network (CAN) (not shown) so as to be able to exchange data (be able to communicate).

[0026] ECU is an abbreviation for Electronic Control Unit, and is an electronic control circuit whose main components are a microcomputer including a CPU, ROM (flash ROM), RAM, and interfaces. The CPU realizes various functions by executing instructions (routines) stored in the ROM (flash ROM). Note that the functions of multiple types of ECUs may be realized by one ECU (integrated ECU).

[0027] The engine ECU 20 controls an engine (not shown). An accelerator pedal operation amount sensor S1 and an engine sensor S2 are connected to the engine ECU 20. The engine ECU 20 receives detection signals from these sensors.

[0028] The accelerator pedal operation amount sensor S1 detects the amount of operation of an accelerator pedal (not shown) of the vehicle V (i.e., accelerator pedal operation amount AP). When the driver is not depressing the accelerator pedal, the accelerator pedal operation amount AP is "0." As the amount of depression of the accelerator pedal increases, the accelerator pedal operation amount AP increases.

[0029] The engine sensor S2 is a sensor that detects the operating state quantities of a gasoline fuel injection type, spark ignition, internal combustion engine that is the drive source of the vehicle V (not shown). The engine sensor S2 includes a throttle valve opening sensor, an engine speed sensor, an intake air amount sensor, etc.

[0030] Furthermore, engine actuators A1 such as a throttle valve actuator and a fuel injection valve are connected to the engine ECU 20. The engine ECU 20 drives the engine actuators A1 to change the torque generated by the internal combustion engine, thereby adjusting the driving force of the vehicle V.

[0031] The engine ECU 20 determines a target throttle valve opening so that the target throttle valve opening becomes larger as the accelerator pedal operation amount AP becomes larger. The engine ECU 20 drives the throttle valve actuator so that the throttle valve opening coincides with the target throttle valve opening. In addition, the engine ECU 20 controls the throttle valve actuator based on a command from the DAECU 50 during autonomous driving.

[0032] The brake ECU 30 controls a brake (not shown). A wheel speed sensor S3 and a brake pedal operation amount sensor S4 are connected to the brake ECU 30. The brake ECU 30 receives detection signals from these sensors.

[0033] The wheel speed sensor S3 is provided for each wheel of the vehicle V. Each wheel speed sensor S3 generates one pulse signal (wheel pulse signal) every time the corresponding wheel rotates a predetermined angle.

[0034] The brake pedal operation amount sensor S4 detects the operation amount (i.e., the brake pedal operation amount BP) of the brake pedal (not shown) of the vehicle V. When the brake pedal is not operated, the brake pedal operation amount BP is "0." As the depression amount of the brake pedal increases, the brake pedal operation amount BP increases.

[0035] The brake ECU 30 measures the number of pulses per unit time of the wheel pulse signal transmitted from each wheel speed sensor S3, and calculates the rotation speed (wheel speed) of each wheel based on the measured number of pulses. The brake ECU 30 calculates the vehicle speed Vs (actual vehicle speed) of the vehicle V based on the wheel speed of each wheel. As an example, the brake ECU 30 obtains the average value of the wheel speeds of the four wheels as the vehicle speed Vs.

[0036] Furthermore, the brake actuator A2 is connected to the brake ECU 30. The brake actuator A2 includes a hydraulic control actuator. The brake actuator A2 is disposed in a hydraulic circuit (both not shown) between a master cylinder that pressurizes hydraulic oil by the depression force of the brake pedal and a friction brake device including a well-known wheel cylinder provided on each wheel. The brake actuator A2 adjusts the hydraulic pressure supplied to the wheel cylinder to adjust the braking force of the vehicle V.

[0037] The brake ECU 30 determines a "target acceleration having a negative value (i.e., a target deceleration having a positive value)" based on the brake pedal operation amount BP. The brake ECU 30 drives the brake actuator A2 so that the actual acceleration of the vehicle V coincides with the target acceleration. In addition, the brake ECU 30 controls the brake actuator A2 based on a command from the DAECU 50 during autonomous driving.

[0038] The steering ECU 40 controls the steering device. A steering angle sensor S5 and a steering torque sensor S6 are connected to the steering ECU 40. The steering ECU 40 receives detection signals from these sensors. Furthermore, the steering motor M is incorporated in a "steering mechanism (not shown) including a steering wheel (not shown), a steering shaft (not shown) connected to the steering wheel, a steering gear mechanism, etc." of the vehicle V.

[0039] The steering angle sensor S5 detects the steering angle (also called the steering angle or the turning angle) θ of the vehicle V. The steering torque sensor S6 detects the steering torque TR applied to the steering shaft.

[0040] The steering motor M generates torque when power is supplied, and this torque is used to apply a steering assist torque and steer the left and right wheels. That is, the steering motor M can change the steering angle of the vehicle V. The power is supplied from a battery (not shown) mounted on the vehicle V. The amount of power supplied to the steering motor M is controlled by the steering ECU 40.

[0041] The DAECU 50 controls the engine ECU 20, the brake ECU 30, and the steering ECU 40. The DAECU 50 acquires target information, lane information, and environmental information from the camera device 11. Furthermore, the DAECU 50 calculates the vehicle speed Vs, similar to the brake ECU 30. In addition, the DAECU 50 acquires position information such as the current location and destination of the vehicle V, and road information such as the speed limit of the road on which the vehicle is traveling, from the navigation system N. The DAECU 50 controls the engine ECU 20, the brake ECU 30, and the steering ECU 40 based on the vehicle speed Vs, the information acquired from the surrounding recognition system 10, and the navigation system N, to perform driving assistance.

[0042] Furthermore, the vehicle driving assistance device 1 includes an operation switch 60. The operation switch 60 includes a driving assistance switch 61 (for example, a push button type switch operator) for the driver to request the start and end of driving assistance. When the driver operates the operation switch 60 (presses the button) during a period when driving assistance is not being performed, the driving assistance switch 61 transmits a driving assistance start signal to the DAECU 50, which indicates that "the driver is requesting the start of driving assistance (driving assistance start request)". When the DAECU 50 receives the driving assistance start signal, it starts driving assistance. When the driver operates the driving assistance switch 61 during a period when driving assistance is being performed, the driving assistance switch 61 transmits a driving assistance end signal to the DAECU 50, which indicates that "the driver is requesting the end of driving assistance (driving assistance end request)". When the DAECU 50 receives the driving assistance end signal, it ends driving assistance.

[0043] Furthermore, the operation switch 60 includes a vehicle speed setting switch 62 (e.g., a rotary encoder) for specifying the maximum vehicle speed during autonomous driving (hereinafter referred to as the "set speed Vsm"). When the driver operates the vehicle speed setting switch 62, a signal (pulse) indicating the amount of change (increase or decrease) in the set speed Vsm is transmitted to the DAECU 50 according to the manner of operation (e.g., the rotation direction and rotation speed of the rotary encoder). The DAECU 50 changes (increases or decreases) the set speed Vsm (data stored in the RAM) based on the signal received from the vehicle speed setting switch 62. Note that, when the vehicle V is started, the set speed Vsm is set (initialized) to a predetermined value (e.g., "0 km / h"). In addition, the current set speed Vsm is displayed on a display device (not shown).

[0044] (Activation) The DAECU 50, as described below, causes the vehicle V to travel autonomously under a predetermined situation (when a predetermined condition is satisfied). That is, the DAECU 50 recognizes the curvature (curve radius) of the lane on which the vehicle is traveling and recognizes the legal speed VM of the lane based on lane information acquired from the camera device 11 and the navigation system N. The DAECU 50 then adopts the smaller of the set speed Vsm and the legal speed VM (strictly speaking, a speed obtained by adding a predetermined small value to the legal speed VM) as the upper limit speed VL for the autonomous traveling. The DAECU 50 controls the engine ECU 20 and the brake ECU 30 so that the vehicle speed Vs does not exceed the upper limit speed VL, and controls the steering ECU 40 so that the vehicle V travels toward the destination. Furthermore, the DAECU 50 determines whether or not a preceding vehicle exists based on target information acquired from the camera device 11. When there is a preceding vehicle, the DAECU 50 controls the engine ECU 20 and the brake ECU 30 so that the distance between the preceding vehicle and the host vehicle (inter-vehicle distance) is equal to or greater than a distance that is determined in advance according to the vehicle speed Vs.

[0045] In autonomous driving, in order to avoid excessive approach to or collision with a target in front of the vehicle V (e.g., a preceding vehicle), the camera device 11 needs to be able to recognize targets that are farther away than the braking distance of the vehicle V. Hereinafter, the lower limit of the recognizable distance Da of the camera device 11 in autonomous driving is referred to as the "required distance Dn." In other words, in autonomous driving, the recognizable distance Da must be greater than or equal to the required distance Dn. Here, the higher the vehicle speed Vs, the greater the braking distance of the vehicle V. Thus, the required distance Dn correlates with the vehicle speed Vs. As described later, in this embodiment, the required distance Dn is determined based on the upper limit speed VL (Vs≦VL).

[0046] Incidentally, the recognizable distance Da of the camera device 11 (the distance to the farthest target among targets located in front of the vehicle V that can be recognized by the camera device 11) correlates with weather conditions and illuminance. In addition, the recognizable distance Db of the driver (the distance to the farthest target among targets located in front of the vehicle V that can be recognized (visible) by the driver) also correlates with weather conditions and illuminance. Therefore, the DAECU 50 estimates the recognizable distance Da and the recognizable distance Db as described below, and changes the subject of driving operations and the mode of driving assistance according to the estimation results and the required distance Dn.

[0047] (Determination of required distance Dn) 2A, a map M1 (look-up table) showing the relationship between the upper limit speed VL and the required distance Dn is stored in the ROM of the DAECU 50. The braking distance (the distance required to stop the vehicle V by decelerating it with a deceleration and jerk that does not cause discomfort to the occupants) is measured multiple times under each test condition with different vehicle speeds Vs, and the map M1 is constructed based on the average value. The DAECU 50 refers to the map M1 to determine (obtain) the required distance Dn corresponding to the current upper limit speed VL.

[0048] (Estimation of recognizable distance Da) The DAECU 50 obtains image data representing an image obtained by photographing the foreground of the vehicle V from the camera device 11, analyzes the image data, and estimates (calculates) the current recognizable distance Da. For example, when a preceding vehicle exists, the DAECU 50 sequentially measures the distance to the preceding vehicle. Then, the DAECU 50 adopts the measurement result (distance) immediately before the preceding vehicle becomes unrecognizable as the recognizable distance Da. The DAECU 50 may also analyze the image data to recognize a plurality of targets, calculate the distance from the vehicle V to each target, and adopt the distance to the farthest target among them as the recognizable distance Da. For example, the DAECU 50 may calculate the recognizable distance Da based on the degree of deterioration of images of signs, road signs, etc. adjacent to the road (the difference between a normal state (e.g., an image in the daytime on a sunny day) and the current image (e.g., the difference in clarity)).

[0049] (Estimation of recognizable distance Db) As shown in FIG. 2B, a map M2 (lookup table) showing the relationship between the amount of rainfall R and the illuminance B and the recognizable distance Db of a standard driver is stored in the ROM of the DAECU 50. The map M2 is constructed based on the average value of the recognizable distances of a plurality of subjects measured (or calculated based on the experimental results using a simulation device) under each test condition with different amounts of rainfall R and illuminance B. The DAECU 50 calculates the current amount of rainfall R and the illuminance B based on the information acquired from the camera device 11, the rain sensor 12, and the illuminance sensor 13. When recognizing (calculating) the current environment (amount of rainfall R and illuminance B), the DAECU 50 mainly uses the image data acquired from the camera device 11, and may supplementarily use the information acquired from the rain sensor 12 and the illuminance sensor 13. The DAECU 50 then refers to the map M2 to estimate (acquire) the recognizable distance Db corresponding to the current amount of rainfall R and illuminance B.

[0050] (First driving assistance) The DAECU 50 refers to the map M1 to determine the required distance Dn (hereinafter referred to as the required distance Dn[VL0]) corresponding to the current upper limit speed VL (hereinafter referred to as the "upper limit speed VL0"). Then, as shown in FIG. 3(1) and FIG. 4(1), when the current recognizable distance Da (hereinafter referred to as the "recognizable distance Da0") is equal to or greater than the required distance Dn[VL0] (first situation), the DAECU 50 executes a "first driving assistance" that causes the vehicle V to autonomously drive so that the vehicle speed Vs does not exceed the upper limit speed VL0. That is, in this case, the main driving operation of the vehicle V is the DAECU 50. The first driving assistance is executed, for example, during the daytime on a clear day.

[0051] (Second driving assistance) When the recognizable distance Da0 is smaller than the necessary distance Dn[VL0] as shown in (2) of FIG. 3 and (2) of FIG. 4, and is equal to or greater than the current recognizable distance Db (hereinafter referred to as "recognizable distance Db0") as shown in (2) of FIG. 3 (second situation), the DAECU 50 executes the following second driving assistance instead of the first driving assistance. Specifically, the DAECU 50 refers to the map M1 as shown in (2) of FIG. 4, and calculates (obtains) the upper limit speed VL (hereinafter referred to as "upper limit speed VL[Da0]") corresponding to the necessary distance Dn that is the same as (or closest to) the recognizable distance Da0. Here, since the recognizable distance Da0 is shorter than the necessary distance Dn[VL(0)], the upper limit speed VL[Da0] is lower than the upper limit speed VL0. Then, the DAECU 50 executes a "second driving assistance" that causes the vehicle V to drive autonomously so as not to exceed the upper limit speed VL [Da0]. That is, in this case, the main driving operation of the vehicle V is the DAECU 50. The second driving assistance is often executed, for example, when there is fog or backlight. The second driving assistance can be said to be a driving assistance with a lower assistance level than the first driving assistance.

[0052] (Third Driving Assistance) When the recognizable distance Da0 is smaller than the necessary distance Dn[VL0] and smaller than the recognizable distance Db0 as shown in (3) of FIG. 3 (third situation), the DAECU 50 does not execute control of the engine ECU 20, the brake ECU 30, and the steering ECU 40 for autonomous driving of the vehicle V. That is, the DAECU 50 stops control for autonomous driving of the vehicle itself. In this case, the DAECU 50 controls the display device, audio device, etc. of the navigation system N to present predetermined information (images and / or sounds) so that the driver can operate the vehicle (take over). That is, the subject of the driving operation of the vehicle V is the driver (passenger), not the DAECU 50. In this case, when the driver starts driving, the DAECU 50 executes a third driving assistance that presents information for assisting the driver in driving (for example, images and / or sounds showing the position, distance, etc. of an approaching target) based on information acquired from the surrounding recognition system 10, the navigation system N, etc. The third driving assistance is often performed, for example, when the amount of rainfall is relatively large. If the driver does not start driving within a predetermined time after the above-mentioned predetermined information is presented, the DAECU 50 stops the vehicle V.

[0053] Next, the operation of the DAECU 50 will be described in more detail with reference to Fig. 5. When the DAECU 50 receives a driving assistance start request signal from the driving assistance switch 61, the DAECU 50 starts executing the driving assistance program shown in the figure. The DAECU 50 starts the driving assistance process from step 500. Next, in step 501, the DAECU 50 determines the upper limit speed VL0.

[0054] Next, in step 502, the DAECU 50 calculates (estimates) the recognizable distance Da0. Next, in step 503, the DAECU 50 refers to the map M1 to determine (obtain) the required distance Dn[VL0]. Next, in step 504, the DAECU 50 determines whether or not the first driving assistance can be performed. Specifically, the DAECU 50 determines whether or not the recognizable distance Da0 is equal to or greater than the required distance Dn[VL0]. If the recognizable distance Da0 is equal to or greater than the required distance Dn[VL0] (step 504: Yes), the DAECU 50 proceeds to step 505. The DAECU 50 performs the first driving assistance in step 505. That is, the DAECU 50 controls the engine ECU 20 and the brake ECU 30 so that the vehicle speed Vs does not exceed the upper limit speed VL0, and controls the steering ECU 40 so that the vehicle V travels toward the destination. Then, the DAECU 50 returns to step 501.

[0055] In step 504, if the recognizable distance Da0 is smaller than the required distance Dn[VL0] (step 504: No), the DAECU 50 proceeds to step 506. In step 506, the DAECU 50 estimates (acquires) the recognizable distance Db0. Next, in step 507, the DAECU 50 determines whether the second driving assistance can be performed. Specifically, the DAECU 50 determines whether the recognizable distance Da0 is equal to or greater than the recognizable distance Db0. If the recognizable distance Da0 is equal to or greater than the recognizable distance Db0 (step 507: Yes), the DAECU 50 performs the second driving assistance in step 508. That is, the DAECU 50 controls the engine ECU 20 and the brake ECU 30 so that the vehicle speed Vs does not exceed the upper limit speed VL[Da0], and controls the steering ECU 40 so that the vehicle V travels toward the destination. Then, the DAECU 50 returns to step 501.

[0056] In step 507, if the recognizable distance Da0 is smaller than the recognizable distance Db0 (step 507: No), the DAECU 50 proceeds to step 509. In step 509, the DAECU 50 performs a process of not executing control for autonomously driving the host vehicle. Specifically, if the DAECU 50 is executing the first driving assistance and the second driving assistance, the execution of these driving assistances is stopped. Note that, if the DAECU 50 is not executing control for autonomously driving the host vehicle, this state is maintained. In addition, the DAECU 50 executes the third driving assistance. That is, the DAECU 50 assists the driving operation by the driver. Then, the DAECU 50 returns to step 501.

[0057] As described above, the DAECU 50 repeatedly executes the process consisting of steps 501 to 509. For example, in the daytime on a clear day, the recognizable distance Da0 is often equal to or greater than the required distance Dn[VL0]. In this case, the DAECU 50 proceeds from step 504 to step 505, and the DAECU 50 executes the driving operation. Thereafter, as the weather worsens, the recognizable distance Da0 gradually decreases. When the recognizable distance Da0 becomes smaller than the required distance Dn[VL0], the DAECU 50 proceeds from step 504 to step 506. The DAECU 50 switches the subject of the driving operation according to the magnitude relationship between the recognizable distance Da0 and the recognizable distance Db0. That is, if the recognizable distance Da0 is equal to or greater than the recognizable distance Db0, the DAECU 50 executes the driving operation, and if the recognizable distance Da0 is smaller than the recognizable distance Db0, the DAECU 50 makes the driver (passenger) execute the driving operation. Thereafter, as the weather improves, the recognizable distance Da0 gradually increases. When the recognizable distance Da0 becomes equal to or greater than the required distance Dn[VL0], the DAECU 50 executes the first driving assistance.

[0058] If the DAECU 50 receives a driving assistance stop signal while the driving assistance program is being executed, the DAECU 50 ends the driving assistance program. Also, if the driver starts driving while the first driving assistance or the second driving assistance is being executed, the DAECU 50 ends the driving assistance program or temporarily executes the third driving assistance.

[0059] (effect) As described above, in a situation where the visibility by the periphery recognition system 10 is considered to be poor, specifically, in a situation where the recognizable distance Da0 is less than the required distance Dn[VL0], when the periphery recognition system 10 can recognize a target farther than the driver, the DAECU 50 becomes the main driver of the driving operation of the vehicle V. Conversely, when the driver can recognize a target farther than the periphery recognition system 10, the driver (passenger) becomes the main driver of the driving operation of the vehicle V. Therefore, the vehicle driving assistance device 1 is more practical than the conventional device. Also, when the driver is the main driver of the driving operation, the third driving assistance is executed. Therefore, safety is improved compared to a case where the third driving assistance is not executed. Also, the DAECU 50 determines the recognizable distance Db0 by referring to the map M2. According to this, the recognizable distance Db0 can be determined more easily than, for example, a case where the driver is observed using a camera that captures the inside of the vehicle and the driver's recognizable distance is obtained based on the observation result.

[0060] The present invention is not limited to the above-described embodiment, and various modifications can be adopted within the scope of the present invention, as described below.

[0061] <Variation 1> The surrounding recognition system 10 may include a radar device 14 in addition to the above-mentioned camera device 11, rain sensor 12, and illuminance sensor 13. As the radar device 14, for example, a laser radar (LiDAR) having a light emitting unit that emits laser light and a light receiving unit that receives reflected light of the laser light (light that is the laser light emitted from the light emitting unit and reflected by a target) may be adopted. Also, as the radar device 14, for example, a millimeter wave radar having a transmitter that emits radio waves (millimeter waves) and a receiver that receives the reflected waves of the radio waves may be adopted.

[0062] In this case, the recognizable distance Da11 of the camera device 11 and the recognizable distance Da14 of the radar device 14 may be calculated (estimated) and their average value may be used as the recognizable distance Da0. Also, in this case, the larger of the recognizable distance Da11 of the camera device 11 and the recognizable distance Da14 of the radar device 14 may be used as the recognizable distance Da0.

[0063] Incidentally, there are cases where the camera device 11 can recognize targets that are farther away than the radar device 14. Conversely, there are cases where the radar device 14 can recognize targets that are farther away than the camera device 11. In this regard, the priority of the recognition results of the camera device 11 and the radar device 14 may be changed according to, for example, the vehicle speed Vs, the amount of rainfall R, the illuminance B, and the like.

[0064] For example, as shown in Fig. 6, when the vehicle speed Vs is equal to or greater than a predetermined threshold Vsth, the recognizable distance Da11 may be adopted as the recognizable distance Da0, and when the vehicle speed Vs is less than the threshold Vsth, the recognizable distance Da14 may be adopted as the recognizable distance Da0. When the vehicle speed Vs is less than the threshold Vsth, the average value of the recognizable distances Da11 and Da14 may be adopted as the recognizable distance Da0. When the vehicle speed Vs is less than the threshold Vsth, the larger of the recognizable distances Da11 and Da14 may be adopted as the recognizable distance Da0.

[0065] Also, for example, the recognizable distance Da11 may be adopted as the recognizable distance Da0 on a fine day or during the day, and the recognizable distance Da14 may be adopted as the recognizable distance Da0 on a rainy day or at night.

[0066] <Variation 2> The map M1 is constructed based on the average value of the braking distance when the vehicle V is traveling at the upper limit speed VL. Here, the braking distance varies greatly depending on the road surface condition. For example, when it is raining or snowing, the vehicle V is likely to slip, and the braking distance becomes relatively long. Therefore, the DAECU 50 may calculate (estimate) the slip degree SL, which indicates the ease with which the vehicle V slips, based on information acquired from the wheel speed sensor S3, the camera device 11, the rain sensor 12, the navigation system N, and the like. In this case, as shown in FIG. 7, the map M1 may be a multidimensional map (multidimensional array) in which the slip degree SL is used as a parameter (search key) in addition to the upper limit speed VL. Then, the DAECU 50 may refer to the multidimensional map to determine the required distance Dn.

[0067] <Variation 3> The map M2 is constructed based on the average value of the recognizable distances of a plurality of subjects. Here, the recognizable distance of the driver of the vehicle V may differ from the above-mentioned "average value of the recognizable distances of a plurality of subjects." Therefore, the DAECU 50 may correct the map M2 based on the characteristics of the driving operation of the driver of the vehicle V, as described below.

[0068] For example, assume that the driver of the vehicle is the main driver and begins to depress the brake pedal at timing T0 when the driver recognizes the vehicle ahead.

[0069] If the camera device 11 can recognize a preceding vehicle (hereinafter referred to as a "preceding vehicle VA") at the timing T0, as shown in FIG. 8, the DAECU 50 calculates a distance Δd[T0] from the vehicle V (hereinafter referred to as a "host vehicle VB") to the preceding vehicle VA based on an image acquired from the camera device 11. Furthermore, the DAECU 50 calculates a response distance Δdd (=Vs×Δt) which is a distance traveled by the vehicle V from when the driver recognizes the preceding vehicle VA until when the driver starts to depress the brake pedal. Here, the time Δt required from when the driver recognizes the preceding vehicle until when the driver starts to depress the brake pedal is determined as follows. For example, the DAECU 50 may determine the time Δt by learning the characteristics of the driving behavior of the driver of the host vehicle. Then, the DAECU 50 adopts an estimated value DD obtained by adding the response distance Δdd to the distance Δd[T0] as the distance between the host vehicle VB and the preceding vehicle VA at the time when the driver actually recognizes the preceding vehicle VA.

[0070] Next, the DAECU 50 refers to the map M2 before correction to acquire the recognizable distance Db0 corresponding to the current amount of rainfall R1 and illuminance B1. Next, the DAECU 50 corrects the map M2 based on the difference between the estimated value DD and the acquired recognizable distance Db0. For example, as shown in FIG. 9, the DAECU 50 calculates an average value Dm of the estimated value DD and the recognizable distance Db0. Then, the DAECU 50 updates the recognizable distance Db0 corresponding to the current amount of rainfall R1 and illuminance B1 in the existing map M2 to the average value Dm.

[0071] On the other hand, if the camera device 11 cannot recognize the preceding vehicle VA at the timing T0, the DAECU 50 waits until the camera device 11 recognizes the preceding vehicle VA. At the timing T1 when the camera device 11 recognizes the preceding vehicle VA, as shown in FIG. 10, the DAECU 50 calculates the distance ΔdAB[T1] from the host vehicle VB to the preceding vehicle VA based on the image acquired from the camera device 11. Next, the DAECU 50 estimates the distance ΔdA[T1-T0] traveled by the preceding vehicle VA from the timing T0 to the timing T1 based on the behavior of the preceding vehicle VA at the timing T1 (for example, the acceleration (deceleration) and speed of the preceding vehicle VA). Furthermore, the DAECU 50 records the vehicle speed Vs of the host vehicle VB as vehicle speed data at every predetermined time interval. The DAECU 50 calculates the distance ΔdB[T1-T0] traveled by the host vehicle VB from the timing T0 to the timing T1 based on the vehicle speed data. The distance ΔdAB[T0] between the preceding vehicle VA and the host vehicle VB at time T0 is obtained by subtracting the distance ΔdA[T1-T0] from the value obtained by adding the distance ΔdAB[T1] to the distance ΔdB[T1-T0] (see (Equation 1) below). (Equation 1) ΔdAB[T0]=ΔdAB[T1]+ΔdB[T1-T0]−ΔdA[T1-T0]

[0072] Next, the DAECU 50 adopts the estimated value DD obtained by adding the response distance Δdd to the distance ΔdAB[T0] as the distance between the host vehicle VB and the preceding vehicle VA at the time when the driver actually recognizes the preceding vehicle. Then, the DAECU 50 corrects the map M2 as shown in FIG.

[0073] According to this, the driver's recognition ability (personality) is reflected in the map M2, so that the practicality of the vehicle driving assistance device 1 is further improved.

[0074] <Modification 4> The DAECU 50 may learn the characteristics of the driver's driving behavior and correct the map M2 based on the results. Specifically, when the driver is the main driver of the driving operation and the DAECU 50 follows the preceding vehicle, the DAECU 50 acquires the following distance ΔL at the time when the host vehicle approaches the preceding vehicle and the driver starts to depress the brake pedal, the subsequent deceleration Va, the deceleration jerk J, and the like, and stores these as feature data. Then, the DAECU 50 compares the average value of the accumulated feature data with a standard value, and corrects the map M2 based on the comparison result. Specifically, when the following distance ΔL is smaller than the standard value and the deceleration Va and the deceleration jerk J are larger than the standard values ​​(sudden braking), it is highly likely that the recognizable distance Db of the driver of the host vehicle V is smaller than the standard value. Therefore, in this case, the DAECU 50 reduces each recognizable distance Db in the map M2. For example, the DAECU 50 stores a value obtained by subtracting a predetermined value (or a value according to the difference between the compared average value and the standard value) from each recognizable distance Db as a new recognizable distance Db.

[0075] <Other Modifications> In the above embodiment, the DAECU 50 executes the third driving assistance in the third situation, but the DAECU 50 does not have to execute the third driving assistance in the third situation. The DAECU 50 may also obtain information on the road structure, surrounding buildings, and the like from the navigation system N (and / or a short-range communication device, not shown), and may estimate the recognizable distance Da of the camera device 11 (and / or the radar device 14) after distinguishing between targets on the lane and other targets based on this information. [Explanation of symbols]

[0076] 1...vehicle driving assistance device, 20...engine ECU, 30...brake ECU, 40...steering ECU, 50...driving assistance ECU (DAECU), Da...recognizable distance (system recognizable distance), Db...recognizable distance (driver recognizable distance), Dn...required distance

Claims

1. A surrounding recognition system that recognizes targets around the host vehicle; a sensor for detecting a current speed of the host vehicle; a control device that controls the host vehicle based on a recognition result of the surrounding recognition system and information acquired from the sensor; A vehicle driving assistance device comprising: The control device includes: When a system recognizable distance, which is the distance to the farthest target that can be recognized by the surrounding recognition system, correlates with either one or both of the weather condition and the illuminance outside the vehicle, the system recognizable distance is estimated, and further, a driver recognizable distance, which is the distance to the farthest target that can be recognized by the driver of the vehicle, is estimated; If the estimated system recognizable distance is equal to or greater than a required distance that is a distance required to execute a first driving assistance for autonomously driving the host vehicle by controlling a drive device and / or a braking device of the host vehicle so that the current speed of the host vehicle does not exceed a speed preset by a driver of the host vehicle, and is greater than a braking distance corresponding to the current speed of the host vehicle, execute the first driving assistance; When the estimated system recognizable distance is smaller than the required distance and is equal to or greater than the estimated driver recognizable distance, a second driving assistance is executed to autonomously drive the host vehicle by controlling a drive device and / or a brake device of the host vehicle so that the current speed of the host vehicle does not exceed a speed corresponding to the system recognizable distance; When the estimated system recognizable distance is shorter than the required distance and shorter than the estimated driver recognizable distance, control for causing the host vehicle to travel autonomously is not executed. A vehicle driving assistance device configured as above.

2. The vehicle driving support device according to claim 1, A vehicle driving assistance device, wherein when the estimated system recognizable distance is smaller than the required distance and smaller than the estimated driver recognizable distance, the control device executes a third driving assistance to assist the driver's driving operation.

3. The vehicle driving support device according to claim 1 or 2, The control device includes: determining a current driver recognizable distance by referring to a lookup table that specifies a relationship between the weather and / or the illuminance outside the vehicle and the driver recognizable distance; A vehicle driving assistance device configured as above.

4. The vehicle driving support device according to claim 3, The control device includes: a vehicle distance between the vehicle and the preceding vehicle when a driver of the vehicle starts to depress a brake pedal while the vehicle is following the preceding vehicle, and a subsequent deceleration and deceleration jerk of the vehicle are stored as feature data, and when an average value of the vehicle distance as the feature data is smaller than a standard value of the vehicle distance and each average value of the deceleration and the deceleration jerk as the feature data is larger than a standard value of the deceleration and the deceleration jerk, the lookup table is corrected by subtracting a predetermined value or a value determined according to a difference between the standard value and the average value from each driver recognizable distance constituting the lookup table, determining a current driver recognizable distance by referring to the corrected lookup table; A vehicle driving assistance device configured as above.

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