Driving assistance method and driving assistance device

Abstract

The present invention provides a driver assistance method and a driver assistance device that can suppress unnecessary acceleration of a vehicle in driving situations where slow speed is required. [Solution] A reference characteristic of the vehicle's acceleration gain in relation to the amount of depression of at least one of the vehicle's accelerator pedal and brake pedal is set in advance. When it is determined that the vehicle's driving scene is a predetermined scene in which the vehicle is moving slowly, and the amount of depression is less than a predetermined first threshold, a second gain smaller than the first gain of the reference characteristic is set. The second gain is set so that if the amount of depression is less than a predetermined second threshold which is less than the first threshold, it decreases as the amount of depression increases, and if the amount of depression is greater than or equal to the second threshold but less than the first threshold, it increases as the amount of depression increases.

Description

Technical Field

[0001] The present invention relates to a driving support method and a driving support device.

Background Art

[0002] When the vehicle is stopped, if the position of the shift lever is in the non-driving range and a sudden depression of the accelerator pedal is detected, the throttle opening of the engine is restricted. When the position of the shift lever shifts from the non-driving range to the driving range while the accelerator pedal is continuously depressed, acceleration is performed up to a predetermined driving speed through low-speed driving. A vehicle sudden acceleration suppression device is known (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above prior art, when the amount of depression of the accelerator pedal is relatively small, the acceleration of the vehicle is not suppressed. Therefore, there is a problem that the vehicle may accelerate unnecessarily in a driving scene where slow driving is required.

[0005] The problem to be solved by the present invention is to provide a driving support method and a driving support device that can suppress unnecessary acceleration of the vehicle in a driving scene where slow driving is required.

Means for Solving the Problems

[0006] The present invention solves the above problem by setting a reference characteristic of the vehicle's acceleration gain in relation to the amount of depression of at least one of the vehicle's accelerator pedal and brake pedal, determining that the vehicle's driving scene is a predetermined scene in which the vehicle is moving slowly, and setting a second gain smaller than the first gain of the reference characteristic when the amount of depression is less than a predetermined first threshold, and setting the second gain to decrease as the amount of depression increases when the amount of depression is less than a predetermined second threshold which is less than the first threshold, and to increase as the amount of depression increases when the amount of depression is greater than or equal to the second threshold but less than the first threshold. [Effects of the Invention]

[0007] According to the present invention, it is possible to suppress unnecessary acceleration of a vehicle in driving situations where slow speed is required. [Brief explanation of the drawing]

[0008] [Figure 1] This is a block diagram showing one embodiment of the driver assistance system according to the present invention. [Figure 2] Figure 1 is a plan view showing an example of a driving scenario in which driver assistance is performed by the driver assistance system. [Figure 3] This figure shows an example of acceleration set by the driver assistance system in Figure 1. [Figure 4] This figure shows another example of acceleration set by the driver assistance system in Figure 1. [Figure 5] This figure shows another example of acceleration set by the driver assistance system in Figure 1. [Figure 6] Figure 1 is a flowchart showing an example of the processing procedure performed in the driver assistance system. [Figure 7] Figure 6 is a flowchart showing an example of the subroutine for step S5. [Figure 8] Figure 6 is a flowchart showing another example of the subroutine in step S5. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. In the following description, it is assumed that vehicles travel on the left side of the road in countries with left-hand traffic regulations. In countries with right-hand traffic regulations, vehicles travel on the right side of the road, so the terms "right" and "left" in the following description should be interpreted symmetrically.

[0010] [Configuration of the driver assistance system] Figure 1 is a block diagram showing one embodiment of the driver assistance system according to the present invention (hereinafter also referred to as this embodiment). The driver assistance system is an in-vehicle system installed in a vehicle, and assists the driver of the vehicle (hereinafter also referred to as the driver) when the vehicle is traveling from its current location to a destination set by the vehicle's occupants (hereinafter also simply referred to as the destination). In the following description, assisting the driver's driving operations will also be referred to as driver assistance. The driver assistance system may also provide information related to driver assistance to the vehicle's occupants.

[0011] As shown in Figure 1, the driver assistance system 10 of this embodiment includes an imaging device 11, a distance measuring device 12, an in-vehicle sensor 13, a map database 14, a vehicle position detection device 15, a navigation device 16, an actuator 17, a display device 18, and a driver assistance device 20. The devices constituting the driver assistance system 10 are connected to each other via CAN (Controller Area Network) or other in-vehicle LANs and exchange information with each other.

[0012] The imaging device 11 is a camera equipped with an image sensor such as a CCD, which captures images of objects around the vehicle and generates images that include the objects. The imaging device 11 may also be an infrared camera, a stereo camera, or the like. In addition, to suppress the occurrence of blind spots where objects cannot be captured, multiple imaging devices 11 are installed on the vehicle's front grille, side mirrors, rear bumper, etc.

[0013] The rangefinder 12 detects the relative distance and relative speed between the vehicle and the object. The rangefinder 12 includes a laser radar, millimeter-wave radar, and a LiDAR (light detection and ranging) unit. To suppress the occurrence of blind spots where the object cannot be detected, multiple rangefinders 12 are installed on a single vehicle.

[0014] The objects detected by the imaging device 11 and the distance measuring device 12 are objects present on the road and its surroundings, including road lane boundaries, center lines, road markings, median strips, guardrails, curbs, traffic lights, and pedestrian crossings. The objects also include obstacles that may affect vehicle traffic, such as other automobiles (other vehicles), motorcycles, bicycles, and pedestrians.

[0015] The driver assistance system 20 acquires image information from the imaging device 11 and object position information from the distance measuring device 12, thereby recognizing objects and the driving environment around the vehicle. The acquisition of information by the driver assistance system 20 is performed at predetermined time intervals (for example, every 0.1 to 1 millisecond). The driver assistance system 20 may also recognize the driving environment by integrating or combining the information acquired from the imaging device 11 and the distance measuring device 12.

[0016] The on-board sensors 13 detect the vehicle's driving state. The on-board sensors 13 include a speed sensor, an acceleration sensor, a yaw rate sensor, a steering angle sensor, and the like. Any known sensors can be used without any particular limitations, and their arrangement and number can be appropriately set within a range that allows for proper detection of the vehicle's driving state. The driver assistance device 20 acquires the detection results of each sensor at predetermined time intervals (for example, every 0.1 to 1 millisecond).

[0017] The map database 14 is a storage medium storing map information and is provided inside or outside the vehicle. The driving support device 20 acquires map information from the map database 14 as necessary. The map information includes information on nodes corresponding to specific points (such as intersections) on a road where the traveling direction of the vehicle (hereinafter also simply referred to as the traveling direction) changes, and links corresponding to road sections connecting the nodes. The information of the nodes includes position information, information regarding entry into and exit from intersections, etc., and the information of the links includes road width, radius of curvature of the road, structures of the road shoulders, road traffic regulations, etc. Note that the map information may be high-precision map information capable of grasping the movement trajectory for each lane.

[0018] The own vehicle position detection device 15 is a positioning system that detects the current position of the vehicle, and calculates the current position of the vehicle from, for example, radio waves received from satellites for GPS (Global Positioning System). Also, the own vehicle position detection device 15 may estimate the current position of the vehicle from the traveling speed information and acceleration information acquired from the vehicle-mounted sensor 13, and calculate the current position of the vehicle by comparing the estimated current position with the map information. The driving support device 20 acquires information regarding the current position of the vehicle as necessary.

[0019] The navigation device 16 refers to the map information and calculates a traveling route from the current position of the vehicle detected by the own vehicle position detection device 15 to the destination set by the occupant. The traveling route includes at least information on the road on which the vehicle travels, the traveling lane, and the traveling direction, and is displayed linearly, for example. The driving support device 20 acquires information regarding the calculated traveling route as necessary.

[0020] The actuator 17 is a device that converts an electrical control signal input from the driving support device 20 into mechanical work, and includes a servo motor, a hydraulic motor, a hydraulic cylinder, etc. The actuator 17 operates the driving device, braking device, steering device, etc. of the vehicle.

[0021] The display device 18 provides information to the vehicle occupants. The display device 18 is, for example, a projector such as a liquid crystal display or head-up display provided on the instrument panel, and may include an input device for the occupants to input instructions to the driver assistance device 20, and a speaker as an output device.

[0022] The driver assistance device 20 controls and coordinates the devices that constitute the driver assistance system 10 to perform driver assistance. In this embodiment, the driver assistance is performed when the driver operates at least one of the vehicle's accelerator pedal and brake pedal. The operation of the pedal not operated by the driver, and the operation of the vehicle's steering wheel, may be controlled by the driver assistance device 20 or performed manually by the driver. In the following description, the accelerator pedal and brake pedal will be collectively referred to as pedals.

[0023] The control of the pedals and steering wheel by the driver assistance system 20 is performed as part of autonomous driving control. Autonomous driving control is the autonomous control of the vehicle's driving actions, which include all driving actions such as acceleration, deceleration, starting, stopping, and steering. The driver assistance system 20 performs autonomous control of driving actions using devices installed in the vehicle and controls the driving actions within a predetermined range. Driving actions that are not controlled by the driver assistance system 20 are operated manually by the driver. When the driver operates the vehicle manually, the driver assistance system 20 does not perform autonomous control of driving actions, and the vehicle's driving actions are controlled by the driver's operation.

[0024] The driver assistance device 20 is, for example, a computer and includes a CPU (Central Processing Unit) which is a processor, a ROM (Read Only Memory) where programs are stored, and a RAM (Random Access Memory) which functions as an accessible storage device. The CPU is the operating circuit that executes the programs stored in the ROM and realizes the functions of the driver assistance device 20. Alternatively, an MPU (Micro Processing Unit), ASIC (Application Specific Integrated Circuit), etc., may be used instead of or in conjunction with the CPU.

[0025] The vehicle according to this embodiment is equipped with at least one of a throttle-by-wire drive system and a brake-by-wire braking system. In the throttle-by-wire drive system, the accelerator pedal and the actuator 17 of the drive system are electrically connected via a driver assistance device 20, and the driving force of the drive system is electrically controlled in accordance with the driver's operation of the accelerator pedal. Similarly, in the brake-by-wire braking system, the brake pedal and the actuator 17 of the braking system are electrically connected via a driver assistance device 20, and the braking force of the braking system is electrically controlled in accordance with the driver's operation of the brake pedal.

[0026] The vehicle according to this embodiment may be a vehicle equipped with an automatic transmission (hereinafter also referred to as an AT vehicle) or a vehicle equipped with a manual transmission (hereinafter also referred to as an MT vehicle). Furthermore, the vehicle according to this embodiment may be any of the following: a vehicle powered solely by an engine, a hybrid vehicle powered by both an engine and a motor, or an electric vehicle powered solely by a motor.

[0027] [Functions of driver assistance systems] The ROM of the driver assistance device 20 stores a program for assisting the vehicle's operation, and the CPU of the driver assistance device 20 executes this program to provide driver assistance. Figure 1 shows the determination unit 21 and the setting unit 22 as functional blocks for performing driver assistance, extracted for convenience.

[0028] The determination unit 21 acquires information from each device constituting the driver assistance system 10 and recognizes the driving environment around the vehicle (hereinafter also simply referred to as the driving environment) based on the acquired information. The determination unit 21 acquires information such as, for example, information related to images captured by the imaging device 11 (hereinafter also referred to as image information), location information of objects measured by the distance measuring device 12 (hereinafter also simply referred to as location information of objects), information related to the detection results of the on-board sensors 13 (hereinafter also referred to as detection information), map information stored in the map database 14 (hereinafter also simply referred to as map information), information related to the current location of the vehicle detected by the vehicle position detection device 15 (hereinafter also referred to as current location information), and information related to the driving route set by the navigation device 16 (hereinafter also referred to as driving route information).

[0029] The determination unit 21 determines, based on the recognized driving environment, whether the vehicle's driving scene (hereinafter also simply referred to as the driving scene) is a predetermined scene in which the vehicle must proceed slowly. Slow driving means driving at a slow speed (for example, 1 to 10 km / h) that allows the vehicle to stop immediately. A predetermined scene in which the vehicle must proceed slowly (hereinafter also simply referred to as the predetermined scene) is, for example, a scene in which a vehicle that has started from a standstill needs to proceed slowly for a while after starting. A while after starting means, for example, the period until the determination unit 21 determines that the vehicle can accelerate to the road's speed limit without coming into contact with an obstacle.

[0030] Furthermore, a specified scene is, for example, a scene in which a vehicle may stop immediately after it starts moving from a standstill (or immediately after a moving vehicle begins to accelerate). "Immediately after a vehicle starts moving" refers to, for example, the moment when the vehicle's speed becomes a slow speed after it starts moving from a standstill, and "immediately after a vehicle begins to accelerate" refers to, for example, the moment when the vehicle's speed becomes a slow speed after it begins to accelerate.

[0031] Examples of designated scenarios include situations where obstacles around the vehicle are difficult to see due to obstructions, situations where it is necessary to check for obstacles over a relatively wide area, situations where obstacles are located relatively close to the vehicle, situations where the road the vehicle is traveling on is relatively narrow, and situations where the space available for the vehicle to travel is relatively small. Furthermore, specific examples of designated scenarios include the following scenarios 1 through 8.

[0032] The first scene is one in which the vehicle passes through an intersection where a stop line is provided on the near side in the direction of travel (hereinafter also simply referred to as the near side). The determination unit 21 determines that the driving scene is the first scene if, for example, a stop line located ahead in the direction of travel is detected from the image information, and an intersection existing ahead in the direction of travel is detected from the map information. In the first scene, in order for the driver or the determination unit 21 to check (or determine) whether there are other vehicles traveling on the intersecting road (hereinafter also simply referred to as the intersecting road) that intersects the road on which the vehicle is traveling, the vehicle starts from a standstill, passes the stop line, and then stops again before entering the intersection. The vehicle must proceed slowly in the section from when it starts moving until it stops again on the near side of the intersection.

[0033] The second scene is one in which the vehicle passes through an intersection equipped with traffic signals. The determination unit 21 determines that the driving scene is the second scene if, for example, a traffic signal located ahead in the direction of travel is detected from the image information, and an intersection located ahead in the direction of travel is detected from the map information. In the second scene, for example, the driver or the determination unit 21 checks (or determines) whether there are pedestrians entering the crosswalk provided on the intersecting road, so the vehicle starts moving from a standstill and then stops again before passing the crosswalk. The vehicle needs to proceed slowly in the section from when it starts moving until it stops again just before the crosswalk.

[0034] The third scene is a scene in which a vehicle is driving on a road where traffic congestion is occurring. The determination unit 21 determines that the driving scene is the third scene if, for example, a convoy of multiple preceding vehicles is detected from the location information of the object, the vehicle's driving speed is detected to be a slow speed from the detection result of the speed sensor, and traffic congestion is detected on the road in which the vehicle is traveling from the map information. In the third scene, the distance between the vehicle and the preceding vehicle is relatively short and the driving speed is relatively slow, so the vehicle needs to repeatedly slow down and stop.

[0035] The fourth scene is a scene of driving in a parking lot. The determination unit 21 determines, for example, that the vehicle's current location is inside a parking lot based on map information and current location information, and determines that the driving scene is the fourth scene. In the fourth scene, the vehicle needs to drive at a slow speed to avoid contact with parked vehicles and obstacles in the parking lot.

[0036] The fifth scene is one in which a vehicle enters a facility facing a road by passing through a sidewalk. The determination unit 21 determines, for example, that the driving scene is the fifth scene if it determines from map information, current location information, and driving route information that a sidewalk exists between the vehicle's current location and the destination at a location relatively close to the destination. In the fifth scene, in order to avoid contact with pedestrians moving on the sidewalk, the vehicle must travel at a slow speed, at least while passing through the sidewalk. The facility in the fifth scene is not particularly limited, as long as it is a facility that a vehicle can enter.

[0037] The sixth scene is one in which a vehicle enters the roadway from a facility facing the road, passing through a sidewalk. The determination unit 21 determines, for example, that the driving scene is the sixth scene if it determines from map information and current location information that a sidewalk exists between the current location and the roadway. In the sixth scene, in order to avoid contact with pedestrians moving on the sidewalk, the vehicle must travel at a slow speed, at least while passing through the sidewalk. The facility in the sixth scene is not particularly limited, as long as it is a facility that a vehicle can enter.

[0038] The seventh scene is one in which the vehicle drives through a designated school zone, such as a kindergarten or elementary school. The determination unit 21 determines, for example, that the driving scene is the seventh scene if it determines from the map information and current location information that the vehicle's current location is within a school zone. In the seventh scene, in order to avoid contact with students from nearby elementary schools, the vehicle must drive at a slow speed, at least while passing through the school zone.

[0039] The eighth scene is a scene in which a vehicle is driving on a narrow road without lane markings. The determination unit 21 determines that the driving scene is the eighth scene if, for example, the lane boundary lines of the road are not detected from the position information of the object, and the map information is registered to indicate that the road the vehicle is currently traveling on is a road without lane markings. In the eighth scene, the road is narrow, and pedestrians and oncoming vehicles pass relatively close to the vehicle, so the vehicle needs to slow down to avoid contact with obstacles.

[0040] The setting unit 22 sets the gain (hereinafter simply referred to as the gain) of the vehicle's acceleration (hereinafter simply referred to as acceleration) in relation to the amount of depression (hereinafter simply referred to as the depression amount) of at least one of the vehicle's accelerator pedal and brake pedal. Vehicle acceleration is the acceleration that occurs in the vehicle and includes acceleration that accelerates the vehicle (positive acceleration) and acceleration that decelerates the vehicle (negative acceleration). The setting unit 22 obtains the vehicle's acceleration from the acceleration sensor and the depression amount from the pedal stroke sensors provided on the accelerator pedal and brake pedal.

[0041] Gain is the ratio of acceleration to the amount of pedal depression, and determines the characteristics of the acceleration obtained for a given amount of depression. For example, if a small gain is set for the amount of accelerator pedal depression, the vehicle will experience less acceleration than if a large gain is set for the amount of accelerator pedal depression (i.e., the vehicle will not accelerate as easily even if the accelerator pedal is depressed). Similarly, if a large gain is set for the amount of brake pedal depression, the vehicle will experience greater deceleration than if a small gain is set for the amount of brake pedal depression (i.e., the vehicle will decelerate more easily). The setting unit 22 can appropriately set the gain for each amount of depression within a range that satisfies preset upper and lower limits. The upper and lower limits of the gain can be set to appropriate values ​​according to the vehicle's dynamic performance and the comfort of the occupants.

[0042] The setting unit 22 sets the acceleration obtained by multiplying the amount of depression by a gain as the reference acceleration, and generates a control signal to operate the actuator 17 so that the vehicle experiences an acceleration with an absolute value less than or equal to the reference acceleration. The actuator 17 controls at least one of the drive unit and the brake unit according to the control signal input from the driving support device 20 (setting unit 22), and causes the vehicle to experience an acceleration with an absolute value less than or equal to the reference acceleration in order to achieve or maintain the set target driving speed (or target inter-vehicle distance).

[0043] In this embodiment, a reference acceleration, which is a standard acceleration typically generated in a vehicle, is set in advance, and a reference characteristic of the gain corresponding to the reference acceleration (hereinafter also simply referred to as the reference characteristic) is set in advance. By setting the gain of the reference characteristic (hereinafter also referred to as the first gain) in the setting unit 22, the reference acceleration corresponding to the amount of pedal depression is set as the reference acceleration. The reference acceleration can be set to an appropriate acceleration within a range that does not impair the ride comfort of the occupants.

[0044] Figure 2 is a plan view showing an example of a driving scene in which driving assistance is performed by the driving assistance system 10 of Figure 1. In the driving scene shown in Figure 2, a road with one lane in each direction extends in the vertical and horizontal directions of the drawing, and an intersection C is provided at the point where the two roads intersect (i.e., the hatched area in the center of Figure 2). Vehicles traveling on the road are allowed to proceed straight, turn left, or turn right at intersection C. Vehicle V shown in Figure 2 is stopped at position P1 in lane L1 and is driven by the driver to a destination Px located ahead in the direction of travel of vehicle V.

[0045] In the driving scene shown in Figure 2, the determination unit 21 detects, for example, a stop line H located in front of the vehicle V in the direction of travel from the image information, and an intersection C located in front of the vehicle V in the direction of travel from the map information. Based on the detection of the stop line H and intersection C, the determination unit 21 determines that the driving scene of vehicle V corresponds to the first scene. The setting unit 22 sets the gain based on the determination result of the determination unit 21.

[0046] In the driving scene shown in Figure 2, the driver of vehicle V starts vehicle V from position P1 and drives vehicle V slowly until it passes the stop line H and stops at position P2 just before intersection C. After stopping vehicle V at position P2, the driver checks whether there are any other vehicles traveling on the intersecting roads extending in the left-right direction in the diagram before entering intersection C. If it is confirmed that there are no other vehicles traveling on the intersecting roads, the driver starts vehicle V from position P2 and enters intersection C, driving to position P3.

[0047] In this case, the driver of vehicle V needs to accurately operate the accelerator pedal within a small range of pedal depression when slowing vehicle V down to position P2. However, accurately operating the pedal within a small range of pedal depression is generally not easy. In particular, if the driver is an elderly person whose leg muscles have weakened with age, or a person with an ankle injury that limits the range of motion of the ankle joint, they may not be able to operate the accelerator pedal accurately, and vehicle V may accelerate unnecessarily.

[0048] Therefore, when the setting unit 22 determines that the driving scene is a predetermined scene, if the amount of pedal depression is less than a predetermined first threshold, it sets a gain (hereinafter also referred to as the second gain) that is smaller than the gain of the pre-set reference characteristic (i.e., the first gain). The first threshold can be set to an appropriate value within the range in which the driver can suppress unnecessary acceleration of the vehicle, for example, by setting a value such that the depression rate, which is the ratio of the amount of pedal depression to the maximum amount of pedal depression for each pedal, is 45 to 55%. The second gain is set, for example, such that the ratio of the second gain to the first gain (e.g., the ratio of magnitude) for a certain amount of pedal depression is greater than 0 and less than 1. As a result, an acceleration that has the same direction as the reference acceleration and has a smaller absolute value than the reference acceleration (hereinafter also referred to as the suppression acceleration) is set as the reference acceleration.

[0049] Furthermore, the second gain is set to decrease as the amount of depression increases when the amount of depression is less than a predetermined second threshold which is less than the first threshold, and to increase as the amount of depression increases when the amount of depression is greater than or equal to the second threshold but less than the first threshold. In other words, the setting unit 22 sets a second gain that decreases continuously as the amount of depression increases when the amount of depression is less than the second threshold, and sets a second gain that increases continuously as the amount of depression increases when the amount of depression is greater than or equal to the second threshold but less than the first threshold. The second threshold can be set to an appropriate value within a range where the characteristics of the change in suppression acceleration with respect to the amount of depression do not cause discomfort or unpleasantness to the driver. For example, the second threshold may be set to a value about half of the first threshold, or a value where the depression rate is 20-30% may be set to the second threshold.

[0050] Figure 3 shows an example of the reference acceleration set by the setting unit 22 in an AT vehicle when the driving scene is determined to be a predetermined scene. In the graph shown in Figure 3, the horizontal axis represents the degree of pedal depression (unit: none), and the vertical axis represents the acceleration generated in the vehicle (unit: m / s²). In the example shown in Figure 3, the vehicle's shift position (hereinafter also simply referred to as the shift position) is in drive range (D range). Note that for the accelerator pedal, the degree of pedal depression on the horizontal axis may be read as the throttle opening.

[0051] In the example shown in Figure 3, a second gain is set for both the accelerator pedal and the brake pedal. The acceleration A1 shown in Figure 3 represents the suppression acceleration relative to the reference acceleration B1 according to the accelerator pedal depression rate, and the acceleration A2 represents the suppression acceleration relative to the reference acceleration B2 according to the brake pedal depression rate. Acceleration A1 represents the positive acceleration corresponding to the accelerator pedal depression rate, and acceleration A2 represents the negative acceleration (i.e., deceleration) corresponding to the brake pedal depression rate. Note that the positive acceleration set when the depression rate is 0 in acceleration A1 and reference acceleration B1 corresponds to the maximum acceleration that occurs in the vehicle when the AT vehicle moves forward in creep mode.

[0052] In the example shown in Figure 3, a first threshold corresponding to the depression rate X1 is set for the accelerator pedal, and a second gain is set in the range from 0 to the first threshold (i.e., the range where the depression rate is from 0 to X1). In the example shown in Figure 3, a second threshold corresponding to the depression rate X2 is also set, and the second gain continuously decreases in the range from 0 to the second threshold (i.e., the range where the depression rate is from 0 to X2), and continuously increases in the range from the second threshold to the first threshold (i.e., the range where the depression rate is from X2 to X1). As a result, the suppression acceleration A1 changes continuously. In addition, in the range from 0 to the second threshold (i.e., the range where the depression rate is from 0 to X2), the magnitude of the absolute value of the acceleration does not increase easily (it does not change easily). On the other hand, in the range where the depression rate is greater than the first threshold (i.e., the range where the depression rate is greater than X1), the first gain is set. Therefore, in the example shown in Figure 3, when the accelerator pedal depression is in the range from 0 to the first threshold (i.e., the accelerator pedal depression ratio is in the range from 0 to X1), acceleration A1 is set as the reference acceleration, and when the accelerator pedal depression is greater than the first threshold (i.e., the accelerator pedal depression ratio is greater than X1), reference acceleration B1 is set as the reference acceleration.

[0053] Similarly, in the example shown in Figure 3, a first threshold corresponding to the pedal depression rate X3 is set for the brake pedal, and a second gain is set in the range from 0 to the first threshold (i.e., the range where the pedal depression rate is 0 to X3). Also in the example shown in Figure 3, a second threshold corresponding to the pedal depression rate X4 is set, and the second gain continuously decreases in the range from 0 to the second threshold (i.e., the range where the pedal depression rate is 0 to X4), and the second gain continuously increases in the range from the second threshold to the first threshold (i.e., the range where the pedal depression rate is X4 to X3). As a result, the suppression acceleration A2 changes continuously. In addition, in the range from 0 to the second threshold (i.e., the range where the pedal depression rate is 0 to X4), the magnitude of the absolute value of the acceleration does not increase easily (it does not change easily). On the other hand, in the range where the pedal depression rate is greater than the first threshold (i.e., the range where the pedal depression rate is greater than X3), the first gain is set. Therefore, in the example shown in Figure 3, when the brake pedal depression is in the range from 0 to the first threshold (i.e., the brake pedal depression ratio is in the range from 0 to X3), acceleration A2 is set as the reference acceleration, and when the brake pedal depression is greater than the first threshold (i.e., the brake pedal depression ratio is greater than X3), reference acceleration B2 is set as the reference acceleration.

[0054] As shown in Figure 3, the gain settings allow for suppression of unnecessary acceleration and deceleration of the vehicle by the driver's actions in the range where the pedal depression is relatively small. Furthermore, in the range where the pedal depression is relatively large, smooth acceleration and deceleration can be achieved, reflecting the driver's intentions. In this embodiment, the suppression of acceleration in the range where the pedal depression is relatively small is specified, but the driver assistance device 20 may also suppress acceleration as needed in the range where the pedal depression is relatively large, such as when the driver mistakenly presses the accelerator pedal instead of the brake pedal.

[0055] Figure 4 shows another example of the reference acceleration set by the setting unit 22 in an AT vehicle when the driving scene is determined to be a predetermined scene. Figure 4 shows an example of the second gain set for the accelerator pedal when the shift position is in reverse range (R range).

[0056] The acceleration A3 shown in Figure 4 represents the suppression acceleration relative to the reference acceleration B3, which corresponds to the degree of depression of the accelerator pedal. In the example shown in Figure 4, since the shift position is in reverse range, acceleration A3 represents a negative acceleration corresponding to the degree of depression of the accelerator pedal. Note that the negative acceleration set when the depression rate is 0 in acceleration A3 and reference acceleration B3 corresponds to the maximum acceleration that occurs in the vehicle when the AT vehicle is creeping backward. In the example shown in Figure 4, a second gain is set for all depression amounts (i.e., all depression rates) of the accelerator pedal. Therefore, in the example shown in Figure 4, acceleration A3 is always set to the reference acceleration.

[0057] Figure 5 shows an example of the reference acceleration set by the setting unit 22 when the vehicle is determined to be an electric vehicle and the driving scene is a predetermined scene. Figure 5 also shows an example of the second gain set for the accelerator pedal when the vehicle is driven in one-pedal mode, where acceleration and deceleration of the vehicle are controlled by operating only the accelerator pedal. Note that the shift position of the vehicle shown in Figure 5 is the drive range.

[0058] The acceleration A4 shown in Figure 5 represents the suppression acceleration relative to the reference acceleration B4, depending on the degree to which the accelerator pedal is depressed. The acceleration A4 shown in Figure 5 exhibits the characteristic that, when the depression rate is less than X5, deceleration occurs due to regenerative braking, resulting in negative acceleration (deceleration), and when the depression rate is X5 or greater, acceleration occurs due to motor acceleration, resulting in positive acceleration. Similarly, the reference acceleration B4 exhibits the characteristic that, when the depression rate is less than X6, negative acceleration occurs, and when the depression rate is X6 or greater, positive acceleration occurs.

[0059] In the example shown in Figure 5, a first threshold corresponding to the indentation rate X7 is set, and a second gain is set in the range from 0 to the first threshold (i.e., the range where the indentation rate is from 0 to X7). Also in the example shown in Figure 5, a second threshold corresponding to the indentation rate X8 is set, and the second gain continuously decreases in the range from 0 to the second threshold (i.e., the range where the indentation rate is from 0 to X8), and the second gain continuously increases in the range from the second threshold to the first threshold (i.e., the range where the indentation rate is from X8 to X7). As a result, the suppression acceleration A4 changes continuously. In addition, in the range from 0 to the second threshold (i.e., the range where the indentation rate is from 0 to X8), the magnitude of the absolute value of the acceleration does not increase easily (it does not change easily). On the other hand, in the range where the indentation rate is greater than the first threshold (i.e., the range where the indentation rate is greater than X7), the first gain is set. Therefore, in the example shown in Figure 5, when the accelerator pedal depression is in the range from 0 to the first threshold (i.e., when the accelerator pedal depression ratio is from 0 to X7), acceleration A4 is set as the reference acceleration, and when the accelerator pedal depression is greater than the first threshold (i.e., when the accelerator pedal depression ratio is greater than X7), reference acceleration B4 is set as the reference acceleration.

[0060] The determination unit 21 may determine, based on image information, map information, and current location information, whether or not an intersection exists in the direction of travel of the vehicle within a predetermined range from the current location. If it is determined that there is no intersection in the direction of travel of the vehicle within a predetermined range from the current location, the determination unit 21 repeatedly performs the determination of whether or not an intersection exists in the direction of travel of the vehicle. On the other hand, if it is determined that there is an intersection in the direction of travel of the vehicle within a predetermined range from the current location, the determination unit 21 determines, based on the travel path information, whether or not the vehicle will enter the intersection located in the direction of travel of the vehicle (hereinafter also referred to as the forward intersection). The predetermined range is the range in which obstacles at the intersection can be detected using the imaging device 11, the distance measuring device 12, etc.

[0061] If it is determined that the vehicle will not enter the intersection ahead, the setting unit 22 sets, for example, a first gain. On the other hand, if it is determined that the vehicle will enter the intersection ahead, the setting unit 22 sets a second gain based on the positional relationship between the vehicle and the intersection ahead, using image information, map information, and current position information. That is, while the vehicle is traveling from a position a predetermined distance in front of the intersection ahead to the intersection ahead, the second gain is set to decrease as the amount of pedal depression increases, and while the vehicle is traveling within the intersection ahead, the second gain is set to increase as the amount of pedal depression increases. After the vehicle has passed the intersection ahead, the setting unit 22 sets the first gain.

[0062] As an example, in the driving scene shown in Figure 2, the setting unit 22 sets a second gain that decreases as the amount of pedal depression increases while the vehicle V is traveling from position P1 to position P2, and sets a second gain that increases as the amount of pedal depression increases when the vehicle V is traveling through intersection C (i.e., when the current position of the vehicle V is within the range of intersection C). Furthermore, when the vehicle V passes through intersection C and enters lane L2, the setting unit 22 sets a first gain. The predetermined distance may correspond to, for example, the distance at which lane changes are prohibited before the intersection, or the distance from the intersection to the stop line placed before the intersection, for example, 15 to 25 m.

[0063] The setting unit 22 may set the second gain to a smaller value the shorter the distance from the vehicle's current stopping position to the next stopping position. For example, as shown in the driving scene in Figure 2, if there is no pedestrian crossing between the stop line H and intersection C, the second gain is set to a smaller value than when there is a pedestrian crossing between the stop line H and intersection C. This allows the acceleration of the vehicle V to be suppressed as the distance from position P1 (vehicle's stopping position) to position P2 (next stopping position) decreases.

[0064] The setting unit 22 may set the second gain higher when the vehicle is accelerating while in motion than when the vehicle is starting from a standstill. This allows the vehicle to accelerate quickly and complete the predetermined scene.

[0065] The setting unit 22 may set the second gain to a smaller value as the target driving speed of the road on which the vehicle is traveling decreases. Furthermore, the setting unit 22 may set the first threshold to a smaller value as the target driving speed of the road on which the vehicle is traveling increases. The target driving speed is the speed at which the vehicle can travel smoothly on the road without hindering the movement of other vehicles, and may be the speed limit or actual speed of the road, or the average speed of other vehicles traveling around the vehicle. This allows the second gain to be set based on the driving environment of the road.

[0066] The setting unit 22 may set the second gain to be lower when the shift position is in the reverse range than when the shift position is in the drive range. In other words, the setting unit 22 may set the second gain so that the vehicle does not accelerate as easily when the vehicle is moving in reverse as it does when the vehicle is moving forward. Also, the setting unit 22 may set the first threshold higher when the shift position is in the reverse range than when the shift position is in the drive range.

[0067] The determination unit 21 may determine, based on the image information and the object's position information, whether or not at least one of other vehicles and pedestrians are present around the vehicle. If the determination unit 21 determines that at least one of other vehicles and pedestrians are present around the vehicle, the setting unit 22 sets the second gain to a smaller value than when the determination unit 21 determines that there are no other vehicles or pedestrians around the vehicle. This helps to avoid the vehicle coming into contact with surrounding obstacles.

[0068] The determination unit 21 may determine, based on image information and object position information, whether or not there is an approaching vehicle (hereinafter simply referred to as an approaching vehicle) traveling on the intersecting road and approaching the vehicle when the vehicle is traveling along the route. If the determination unit 21 determines that an approaching vehicle is present, the setting unit 22 sets the second gain to a higher value than when the determination unit 21 determines that no approaching vehicle is present. This allows the vehicle to pass through the intersecting road quickly.

[0069] Furthermore, if the vehicle is traveling along its route and is passing through the opposite lane of the lane it is traveling in, the determination unit 21 may determine, based on image information and object position information, whether or not there is an oncoming vehicle traveling in the opposite lane and approaching the vehicle. If the determination unit 21 determines that an oncoming vehicle is present, the setting unit 22 sets the second gain higher than when the determination unit 21 determines that no oncoming vehicle is present. This allows the vehicle to pass through the oncoming lane quickly.

[0070] The vehicle may be provided with a switch to select whether or not to perform the second gain setting process. For example, as shown in Figure 1, the vehicle may be provided with a switch 20a that indicates whether or not to perform the second gain setting process. The setting unit 22 may also notify the vehicle driver that the second gain has been set. For example, the setting unit 22 may display an image on the display device 18 indicating that the second gain has been set.

[0071] [Processing in driver assistance systems] Referring to Figures 6-8, the procedure for information processing by the driver assistance system 20 will be explained. The processing described below is performed, for example, by the processor (CPU) of the driver assistance system 20 at predetermined time intervals (for example, every 0.1 to 1 millisecond).

[0072] Figure 6 is a flowchart showing an example of a processing procedure performed in the driver assistance system 10 shown in Figure 1.

[0073] First, in step S1, the driver assistance device 20 determines whether the driver has operated the accelerator pedal or the brake pedal based on the amount of depression detected by the pedal stroke sensor. If it is determined that the driver has not operated the accelerator pedal or the brake pedal, the driver assistance device 20 repeats the process in step S1. On the other hand, if it is determined that the driver has operated the accelerator pedal or the brake pedal, the process proceeds to step S2.

[0074] In step S2, the driver assistance device 20 recognizes the driving environment around the vehicle and determines whether the vehicle's driving scene corresponds to a predetermined scene based on the recognized driving environment. If it is determined that the vehicle's driving scene does not correspond to a predetermined scene, the process proceeds to step S7. On the other hand, if it is determined that the vehicle's driving scene corresponds to a predetermined scene, the process proceeds to step S3.

[0075] In step S3, the driver assistance device 20 determines whether the amount of pedal depression detected by the pedal stroke sensor is less than a predetermined first threshold. If it is determined that the amount of depression is equal to or greater than the first threshold, the process proceeds to step S7. On the other hand, if it is determined that the amount of depression is less than the first threshold, the process proceeds to step S4.

[0076] In step S4, the driver assistance device 20 determines whether the driving speed detected by the speed sensor is less than a predetermined speed. If it is determined that the driving speed is less than the predetermined speed, the device proceeds to step S5. In step S5, the driver assistance device 20 sets the acceleration gain with respect to the pedal depression amount to a second gain that is smaller than the first gain of the reference characteristic, and in the subsequent step S6, sets the suppression acceleration corresponding to the second gain to the reference acceleration.

[0077] If it is determined that the driving speed is equal to or greater than the predetermined speed, the process proceeds to step S7. In step S7, the driving support device 20 sets the acceleration gain with respect to the pedal depression amount to the first gain of the reference characteristic, and in the subsequent step S8, sets the reference acceleration to the reference acceleration. The predetermined speed is a slow speed or a speed faster than a slow speed, for example, 15 to 25 km / h.

[0078] Figure 7 is a flowchart showing an example of the subroutine for step S5 in Figure 6.

[0079] First, in step S11, the driver assistance device 20 determines whether the amount of pedal depression detected by the pedal stroke sensor is less than a predetermined second threshold. If it is determined that the amount of depression is less than the second threshold, the process proceeds to step S12. In step S12, the driver assistance device 20 sets the second gain so that the second gain continuously decreases as the amount of depression increases. Conversely, if it is determined that the amount of depression is equal to or greater than the second threshold, the process proceeds to step S13. In step S13, the driver assistance device 20 sets the second gain so that the second gain continuously increases as the amount of depression increases.

[0080] Figure 8 is a flowchart showing another example of the subroutine in step S5 of Figure 6.

[0081] First, in step S21, the driver assistance device 20 determines, based on image information, map information, current location information, etc., whether or not an intersection exists in front of the vehicle in the direction of travel within a predetermined range from the current location. If it is determined that there is no intersection in front of the vehicle in the direction of travel, the process proceeds to step S22. In step S22, the driver assistance device 20 sets a gain according to the driving scene. On the other hand, if it is determined that there is an intersection in front of the vehicle in the direction of travel, the process proceeds to step S23.

[0082] In step S23, the driver assistance device 20 determines whether the vehicle is traveling on the side of the road before the intersection based on map information, current location information, and driving route information. If it is determined that the vehicle is traveling on the side of the road before the intersection, the process proceeds to step S24. In step S24, the driver assistance device 20 sets the second gain so that the second gain decreases continuously as the amount of pedal depression increases. Conversely, if it is determined that the vehicle is not traveling on the side of the road before the intersection, the process proceeds to step S25.

[0083] In step S25, the driver assistance device 20 determines whether or not an obstacle exists in the intersection based on the image information and the position information of the object. If it is determined that an obstacle exists in the intersection, the process proceeds to step S24. Conversely, if it is determined that no obstacle exists in the intersection, the process proceeds to step S26.

[0084] In step S26, the driver assistance device 20 determines whether the vehicle is traveling through an intersection based on image information, map information, current location information, etc. If it is determined that the vehicle is traveling through an intersection, the process proceeds to step S27. In step S27, the driver assistance device 20 sets the second gain so that the second gain increases continuously with increasing pedal depression. Conversely, if it is determined that the vehicle is not traveling through an intersection, the process proceeds to step S28.

[0085] In step S28, the driver assistance device 20 determines whether the vehicle has passed through the intersection based on image information, map information, current location information, etc. If it is determined that the vehicle has not passed through the intersection, the process proceeds to step S26. On the other hand, if it is determined that the vehicle has passed through the intersection, the process proceeds to step S7 in Figure 6, where the driver assistance device 20 newly sets the first gain in place of the second gain.

[0086] [Embodiments of the present invention] According to this embodiment, a reference characteristic of the vehicle's acceleration gain with respect to the amount of depression of at least one of the vehicle's accelerator pedal and brake pedal is set in advance, and when it is determined that the vehicle's driving scene is a predetermined scene in which the vehicle is driving slowly, and the amount of depression is less than a predetermined first threshold, a second gain smaller than the first gain of the reference characteristic is set, and the second gain is set to decrease as the amount of depression increases when the amount of depression is less than a predetermined second threshold which is less than the first threshold, and to increase as the amount of depression increases when the amount of depression is greater than or equal to the second threshold and less than the first threshold, a driving assistance method and a driving assistance device that execute this driving assistance method are provided. This makes it possible to suppress unnecessary acceleration of the vehicle in driving scenes in which slow driving is required.

[0087] In the driving assistance method and driving assistance device of this embodiment, when the vehicle enters an intersection located in front of the vehicle's direction of travel, the second gain is set to decrease as the amount of pedal depression increases while the vehicle travels from a position a predetermined distance before the intersection in the direction of travel to the intersection, the second gain is set to increase as the amount of pedal depression increases while the vehicle is traveling through the intersection, and the first gain is set after the vehicle has passed the intersection. This allows for smooth switching of acceleration when passing through an intersection.

[0088] In the driving assistance method and driving assistance device of this embodiment, the second gain is set to be smaller the shorter the distance from the vehicle's current stopping position to the next stopping position. This makes it possible to suppress the acceleration of the vehicle when the distance from the vehicle's current stopping position to the next stopping position is relatively short.

[0089] In the driving assistance method and driving assistance device of this embodiment, when the vehicle is accelerating while in motion, the second gain is set to be larger than when the vehicle is starting from a standstill. This allows the vehicle to accelerate quickly while in motion.

[0090] In the driving assistance method and driving assistance device of this embodiment, the lower the target driving speed of the road on which the vehicle is traveling, the smaller the second gain is set. This makes it possible to set acceleration according to the driving scene of the vehicle.

[0091] In the driving assistance method and driving assistance device of this embodiment, the higher the target driving speed of the road on which the vehicle is traveling, the smaller the first threshold value is set. This makes it possible to set acceleration according to the driving scene of the vehicle.

[0092] In the driving assistance method and driving assistance device of this embodiment, when the vehicle's shift position is in the reverse range, the second gain is set to be smaller than when the shift position is in the drive range. This allows for greater suppression of acceleration when the vehicle is reversing.

[0093] In the driving assistance method and driving assistance device of this embodiment, when the vehicle's shift position is in the reverse range, the first threshold is set higher than when the shift position is in the drive range. This makes it possible to further suppress acceleration when the vehicle is reversing.

[0094] In the driving assistance method and driving assistance device of this embodiment, if at least one of another vehicle and / or a pedestrian is present around the vehicle, the second gain is set to be smaller than when neither the other vehicle nor the pedestrian is present around the vehicle. This makes it possible to avoid contact with obstacles around the vehicle.

[0095] In the driving assistance method and driving assistance device of this embodiment, when the vehicle passes through an intersecting road that crosses the road on which the vehicle is traveling, if there is an approaching vehicle traveling on the intersecting road that is approaching the vehicle, the second gain is set to be larger than when there is no approaching vehicle. When the vehicle passes through the oncoming lane of the lane on which the vehicle is traveling, if there is an oncoming vehicle traveling on the oncoming lane that is approaching the vehicle, the second gain is set to be larger than when there is no oncoming vehicle. This allows the vehicle to quickly pass through the intersecting road on which the approaching vehicle is traveling and the oncoming lane on which the oncoming vehicle is traveling.

[0096] In the driving assistance method and driving assistance device of this embodiment, the vehicle is provided with a switch that allows the driver to select whether or not to perform the setting process of the second gain. This allows the driver or a dealer's mechanic to select the vehicle's acceleration characteristics according to the driver's attributes.

[0097] In the driving assistance method and driving assistance device of this embodiment, the driver of the vehicle is notified that the second gain has been set. This prevents the driver from feeling discomfort or unease due to an unintended change in acceleration characteristics. [Explanation of Symbols]

[0098] 10...Driving assistance system, 11...Imaging device, 12...Distance measuring device, 13...On-board sensor, 14...Map database, 15...Vehicle position detection device, 16...Navigation device, 17...Actuator, 18...Display device, 20...Driving assistance device, 20a...Switch, 21...Determination unit, 22...Setting unit, A1,A2,A3,A4...Acceleration, B1,B2,B3,B4...Reference acceleration, C...Intersection, L1,L2...Lane, H...Stop line, P1,P2...Position, Px...Destination, V...Vehicle, X1,X2,X3,X4,X5,X6,X7,X8...Pedaling ratio

Claims

1. In a driving assistance method performed by a vehicle's driving assistance system, The aforementioned driving support device, A reference characteristic of the vehicle's acceleration gain for the amount of depression of at least one of the accelerator pedal and brake pedal of the vehicle is set in advance, and if the vehicle's driving scene is determined to be a predetermined scene in which the vehicle is moving slowly, and the amount of depression is less than a predetermined first threshold, a second gain smaller than the first gain of the reference characteristic is set. A driving assistance method wherein the second gain is set to decrease as the amount of depression increases when the amount of depression is less than a predetermined second threshold which is less than the first threshold, and to increase as the amount of depression increases when the amount of depression is greater than or equal to the second threshold and less than the first threshold.

2. The aforementioned driving support device, When the aforementioned vehicle enters an intersection located ahead in the direction of travel of the vehicle, While the vehicle is traveling from a position a predetermined distance before the intersection in the direction of travel to the intersection, the second gain is set to decrease as the amount of pedal depression increases. While the vehicle is traveling through the intersection, the second gain is set to increase as the amount of pedal depression increases. The driving assistance method according to claim 1, wherein the first gain is set after the vehicle has passed the intersection.

3. The driving assistance method according to claim 1 or 2, wherein the driving assistance device sets the second gain to be smaller the shorter the distance from the stopping position where the vehicle is stopped to the next stopping position.

4. The driving assistance method according to claim 1 or 2, wherein the driving assistance device sets the second gain to be larger when the vehicle is accelerating while in motion than when the vehicle is starting from a stationary state.

5. The driving assistance method according to claim 1 or 2, wherein the driving assistance device sets the second gain to be smaller the lower the target driving speed of the road on which the vehicle is traveling.

6. The driving assistance method according to claim 1 or 2, wherein the driving assistance device sets a smaller first threshold as the target driving speed of the road on which the vehicle is traveling increases.

7. The driving assistance method according to claim 1 or 2, wherein the driving assistance device sets the second gain to be smaller when the shift position of the vehicle is in the reverse range than when the shift position is in the drive range.

8. The driving assistance method according to claim 1 or 2, wherein the driving assistance device sets a higher first threshold than when the shift position of the vehicle is in the drive range when the shift position of the vehicle is in the reverse range.

9. The driving assistance method according to claim 1 or 2, wherein the driving assistance device sets the second gain to be smaller when at least one of another vehicle and a pedestrian is present around the vehicle than when there is no other vehicle and no pedestrian around the vehicle.

10. The aforementioned driving support device, When the vehicle passes through an intersecting road that crosses the road on which the vehicle is traveling, if there is an approaching vehicle traveling on the intersecting road that is approaching the vehicle, the second gain is set to be larger than when there is no approaching vehicle. The driving assistance method according to claim 1 or 2, wherein when the vehicle passes in the opposite lane of the lane in which the vehicle is traveling, if there is an oncoming vehicle traveling in the opposite lane and approaching the vehicle, the second gain is set to be larger than when there is no oncoming vehicle.

11. The driving assistance method according to claim 1 or 2, wherein the vehicle is provided with a switch for selecting whether or not to perform the setting process of the second gain.

12. The driving assistance method according to claim 1 or 2, wherein the driving assistance device notifies the driver of the vehicle that the second gain has been set.

13. A reference characteristic of the vehicle's acceleration gain for the amount of depression of at least one of the vehicle's accelerator pedal and brake pedal is set in advance, and when it is determined that the vehicle's driving scene is a predetermined scene in which the vehicle is moving slowly, and the amount of depression is less than a predetermined first threshold, a setting unit is provided to set a second gain that is smaller than the first gain of the reference characteristic. The driving assistance device is configured such that the second gain decreases as the amount of depression increases when the amount of depression is less than a predetermined second threshold which is less than the first threshold, and increases as the amount of depression increases when the amount of depression is greater than or equal to the second threshold but less than the first threshold.

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