Driving assistance method and driving assistance device

Abstract

In the present invention, a reference characteristic of a gain of acceleration of a vehicle with respect to the depression amount of at least one of an accelerator pedal and a brake pedal of the vehicle is set in advance. In cases where it is assessed that the travel scenario of the vehicle is a prescribed scenario in which the vehicle slowly travels and where the depression amount is less than a prescribed threshold value, a gain lower than the gain of the reference characteristic is set.

Description

Driving Support Method and Driving Support Device

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

[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 sudden acceleration suppression device for a vehicle is known (Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2023-144712

[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.

[0006] In the present invention, a reference characteristic of the gain of the vehicle's acceleration with respect to the depression amount of at least one of the accelerator pedal and the brake pedal of the vehicle is preset. When the driving scene of the vehicle is determined to be a predetermined scene where the vehicle travels slowly and the depression amount is less than a predetermined threshold value, the above problem is solved by setting a gain smaller than the gain of the reference characteristic.

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

[0008] Figure 1 is a block diagram showing one embodiment of the driver assistance system according to the present invention. Figure 1 is a plan view showing an example of a driving scene in which driver assistance is performed by the driver assistance system of Figure 1. Figure 1 is a diagram showing an example of acceleration set by the driver assistance system of Figure 1. Figure 1 is a diagram showing another example of acceleration set by the driver assistance system of Figure 1. Figure 1 is a diagram showing yet another example of acceleration set by the driver assistance system of Figure 1. Figure 1 is a flowchart showing an example of a processing procedure performed in the driver assistance system of Figure 1.

[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 Driving Assistance System] Figure 1 is a block diagram showing one embodiment of the driving assistance system according to the present invention (hereinafter also referred to as this embodiment). The driving assistance system is an in-vehicle system installed in a vehicle, and assists the driving operations of the vehicle's driver (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 driving assistance. The driving assistance system may also provide information related to driving 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 a CAN (Controller Area Network) or other in-vehicle LAN, 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 including 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 driver assistance system 20 acquires information 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 sensor 13 detects the vehicle's driving state. The on-board sensor 13 includes a speed sensor, acceleration sensor, yaw rate sensor, steering angle sensor, etc. Known sensors can be used without 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 containing map information and is located inside or outside the vehicle. The driver assistance device 20 retrieves map information from the map database 14 as needed. The map information includes information on nodes corresponding to specific points (such as intersections) on the road where the direction of travel of the vehicle (hereinafter also simply referred to as the direction of travel) changes, and information on links corresponding to road sections connecting the nodes. The node information includes location information, information on entering and exiting intersections, etc., and the link information includes road width, road curvature radius, road shoulder structures, road traffic regulations, etc. The map information may also be high-precision map information that can grasp the movement trajectory for each lane.

[0018] The 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 GPS (Global Positioning System) satellites. Alternatively, the vehicle position detection device 15 may estimate the current position of the vehicle from driving speed information and acceleration information acquired from the on-board sensor 13, and calculate the current position of the vehicle by comparing the estimated current position with map information. The driver assistance device 20 acquires information regarding the current position of the vehicle as needed.

[0019] The navigation system 16 refers to map information and calculates a driving route from the vehicle's current position detected by the vehicle position detection device 15 to the destination set by the occupants. The driving route includes at least information on the road the vehicle is traveling on, the lane it is traveling in, and the direction of travel, and is displayed, for example, as a linear route. The driver assistance device 20 acquires information about the calculated driving route as needed.

[0020] The actuator 17 is a device that converts electrical control signals input from the driver assistance device 20 into mechanical work, and includes servo motors, hydraulic motors, hydraulic cylinders, etc. The actuator 17 operates the vehicle's drive system, braking system, steering system, etc.

[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 device 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 device 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 device 20 are operated manually by the driver. When the driver operates the vehicle manually, the driver assistance device 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) in which programs are stored, and a RAM (Random Access Memory) which functions as an accessible storage device. The CPU is an 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 the Driving Assistance System] The ROM of the driving assistance system 20 stores a program for assisting the vehicle's driving, and the CPU of the driving assistance system 20 executes this program to provide driving assistance. Figure 1 shows the determination unit 21 and the setting unit 22 as functional blocks for providing driving 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 those where obstacles around the vehicle are difficult to see due to obstructions, those where it is necessary to check for obstacles over a relatively wide area, those where obstacles are located relatively close to the vehicle, those where the road the vehicle is traveling on is relatively narrow, and those 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 moving 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 with traffic lights. The determination unit 21 determines that the driving scene is the second scene if, for example, it detects a traffic light located ahead in the direction of travel from the image information and detects an intersection located ahead in the direction of travel 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 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 the vehicle is traveling on 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 a scene in which the vehicle is driving 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 of 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 were set for the amount of accelerator pedal depression (i.e., the vehicle will not accelerate as easily even if the accelerator pedal is depressed). Also, if a large gain is set for the amount of brake pedal depression, the vehicle will experience greater deceleration than if a small gain were 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 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] FIG. 2 is a plan view showing an example of a driving scene in which driving support is executed by the driving support system 10 of FIG. 1. In the driving scene shown in FIG. 2, a road with one lane on each side extends in the vertical and horizontal directions of the drawing, and an intersection C is provided at a portion where two roads intersect. Assume that a vehicle traveling on the road can go straight, turn left, or turn right at intersection C. The vehicle V shown in FIG. 2 is stopped at position P1 in lane L1 and travels toward a destination Px existing ahead in the traveling direction of vehicle V by manual driving of the driver.

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

[0046] In the driving scene shown in FIG. 2, the driver of vehicle V starts vehicle V from position P1 and slowly drives vehicle V until it stops at position P2 on the front side of intersection C after vehicle V passes the stop line H. After stopping vehicle V at position P2, before entering intersection C with vehicle V, the driver checks whether there are other vehicles traveling on the intersecting road extending in the left - right direction of the drawing. And when it is confirmed that there are no other vehicles traveling on the intersecting road, the driver starts vehicle V from position P2, enters intersection C, and travels to position P3.

[0047] In this case, when the driver of vehicle V slowly drives vehicle V to position P2, it is necessary to accurately operate the accelerator pedal within a range where the depression amount of the accelerator pedal is small. However, it is generally not easy to accurately perform pedal operation within a range with a small depression amount. In particular, in the case where the driver is an elderly person whose leg strength has decreased with aging or a person whose ankle has been injured and the range of motion of the ankle joint is limited, the accelerator pedal cannot be accurately operated, 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 threshold, it sets a gain smaller than the gain of the reference characteristic (hereinafter also referred to as the suppression gain). The predetermined threshold can be set to an appropriate value within the range in which the driver can suppress unnecessary acceleration of the vehicle. For example, it is set to 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 greater than 0% and 25% or less. The suppression gain is set, for example, such that the ratio of the suppression gain to the gain of the reference characteristic at a certain amount of pedal depression (for example, the ratio of magnitude) 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] 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). ２ This shows the following. 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 horizontal axis of depression can be interpreted as the throttle opening.

[0050] In the example shown in Figure 3, suppression gains are 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 corresponding to the accelerator pedal depression rate, and the acceleration A2 represents the suppression acceleration relative to the reference acceleration B2 corresponding to the brake pedal depression rate. Acceleration A1 represents a positive acceleration corresponding to the accelerator pedal depression rate, and acceleration A2 represents a 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.

[0051] In the example shown in Figure 3, a predetermined threshold corresponding to the depression rate X1 of the accelerator pedal is set, and a suppression gain is set in the range from 0 to the predetermined threshold (i.e., the range where the depression rate is from 0 to X1). In the example shown in Figure 3, the suppression gain changes continuously in the range from 0 to the predetermined threshold (i.e., the range where the depression rate is from 0 to X1), and as a result, the acceleration A1, which is the suppression acceleration, changes continuously. On the other hand, in the range where the depression rate is greater than the predetermined threshold (i.e., the range where the depression rate is greater than X1), a reference characteristic gain is set. Therefore, in the example shown in Figure 3, in the range from 0 to the predetermined threshold of the accelerator pedal (i.e., the range where the accelerator pedal depression rate is from 0 to X1), the acceleration A1 is set to the reference acceleration, and in the range where the accelerator pedal depression rate is greater than the predetermined threshold (i.e., the range where the accelerator pedal depression rate is greater than X1), the reference acceleration B1 is set to the reference acceleration.

[0052] Similarly, in the example shown in Figure 3, a predetermined threshold corresponding to the depression rate X2 is set for the brake pedal, and a suppression gain is set in the range from 0 to the predetermined threshold (i.e., the range where the depression rate is from 0 to X2). In the example shown in Figure 3, the suppression gain changes continuously in the range from 0 to the predetermined threshold (i.e., the range where the depression rate is from 0 to X2), and as a result, the acceleration A2, which is the suppression acceleration, changes continuously. On the other hand, in the range where the depression rate is greater than the predetermined threshold (i.e., the range where the depression rate is greater than X2), a reference characteristic gain is set. Therefore, in the example shown in Figure 3, in the range from 0 to the predetermined threshold for the brake pedal depression rate (i.e., the range where the brake pedal depression rate is from 0 to X2), the acceleration A2 is set as the reference acceleration, and in the range where the brake pedal depression rate is greater than the predetermined threshold (i.e., the range where the brake pedal depression rate is greater than X2), the reference acceleration B2 is set as the reference acceleration.

[0053] 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.

[0054] 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 suppression gain set for the accelerator pedal when the shift position is in reverse range (R range).

[0055] 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 suppression gain is set for all amounts of depression (i.e., all degrees of depression) of the accelerator pedal. Therefore, in the example shown in Figure 4, acceleration A3 is always set to the reference acceleration.

[0056] 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 suppression 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.

[0057] 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 X3, deceleration occurs due to regenerative braking, resulting in negative acceleration (deceleration), and when the depression rate is X3 or greater, acceleration occurs due to the motor, resulting in positive acceleration. Similarly, the reference acceleration B4 exhibits the characteristic that, when the depression rate is less than X4, negative acceleration occurs, and when the depression rate is X4 or greater, positive acceleration occurs.

[0058] In the example shown in Figure 5, a predetermined threshold corresponding to the depression rate X5 is set, and a suppression gain is set in the range from 0 to the predetermined threshold (i.e., the range where the depression rate is from 0 to X5). In the example shown in Figure 5, the suppression gain changes continuously in the range from 0 to the predetermined threshold (i.e., the range where the depression rate is from 0 to X5), and as a result, the acceleration A4, which is the suppression acceleration, changes continuously. On the other hand, in the range where the depression rate is greater than the predetermined threshold (i.e., the range where the depression rate is greater than X5), a reference characteristic gain is set. Therefore, in the example shown in Figure 5, when the accelerator pedal depression rate is in the range from 0 to the predetermined threshold (i.e., the range where the accelerator pedal depression rate is from 0 to X5), acceleration A4 is set as the reference acceleration, and when the accelerator pedal depression rate is greater than the predetermined threshold (i.e., the range where the accelerator pedal depression rate is greater than X5), the reference acceleration B4 is set as the reference acceleration.

[0059] A designated scene may include a scene in which the vehicle starts moving from a standstill. For example, the first and second scenes fall under this category. A designated scene may also include a scene in which the vehicle is traveling at a speed below a specified speed. The specified speed is a slow speed or a speed faster than a slow speed, for example, 15 to 25 km / h. For example, the third, fourth, seventh, and eighth scenes fall under this category.

[0060] A predetermined scene may include a scene in which a vehicle starts moving from a standstill and may come to a stop before a predetermined time has elapsed. The predetermined time is the time it takes for a vehicle's speed to reach a slow speed when it accelerates at a standard acceleration, for example, 1 to 5 seconds. For example, the first, second, and third scenes fall under this category. A predetermined scene may also include a scene in which a vehicle traveling at a predetermined speed comes to a stop. For example, the third, fourth, seventh, and eighth scenes fall under this category.

[0061] The setting unit 22 may set a suppression gain in at least one of the cases where the accelerator pedal is pressed down more, or where the brake pedal is pressed down less. This ensures that acceleration is reliably suppressed when the vehicle is accelerating. The setting unit 22 may also set a suppression gain when the brake pedal is pressed down more. This prevents the vehicle from suddenly decelerating (or suddenly stopping).

[0062] The setting unit 22 may set the gain for when the brake pedal depression decreases to be greater than the gain for when the accelerator pedal depression increases. This allows the driver to be prompted to perform creep driving in an automatic transmission vehicle. In this case, the gain includes at least one of the reference characteristic gain and the suppression gain.

[0063] The setting unit 22 may set a suppression gain when the amount of accelerator pedal depression decreases while the vehicle is running in one-pedal mode. This can prevent the vehicle from suddenly decelerating (or stopping).

[0064] The setting unit 22 may set the gain when the shift position is in the reverse range to be smaller than the gain when the shift position is in the drive range. In other words, the setting unit 22 may set the gain so that when the vehicle is moving in reverse, the vehicle accelerates less than when the vehicle is moving forward. In this case, the gain includes at least one of the reference characteristic gain and the suppression gain.

[0065] The vehicle may be provided with a switch to select whether or not to execute the suppression 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 execute the suppression gain setting process. The setting unit 22 may also notify the vehicle driver that the suppression gain has been set. For example, the setting unit 22 may display an image on the display device 18 indicating that the suppression gain has been set.

[0066] [Processing in the Driving Assistance System] Referring to Figure 6, the procedure for when the driving assistance device 20 processes information will be explained. Figure 6 is a flowchart showing an example of the processing procedure performed in the driving assistance system 10 of Figure 1. The processing described below is performed, for example, by the processor (CPU) of the driving assistance device 20 at predetermined time intervals (for example, every 0.1 to 1 millisecond).

[0067] 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.

[0068] 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.

[0069] 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 threshold. If it is determined that the amount of depression is equal to or greater than the predetermined threshold, the process proceeds to step S7. On the other hand, if it is determined that the amount of depression is less than the predetermined threshold, the process proceeds to step S4.

[0070] 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 be smaller than the gain of the reference characteristic, and in the subsequent step S6, sets the suppression acceleration corresponding to the suppression gain smaller than the gain of the reference characteristic to the reference acceleration.

[0071] If it is determined that the driving speed is equal to or greater than a predetermined speed, the process proceeds to step S7. In step S7, the driving support device 20 sets the gain of acceleration with respect to the amount of pedal depression to the gain of the reference characteristic, and in the following step S8, sets the reference acceleration to the reference acceleration.

[0072] [Embodiment of the Invention] According to this embodiment, a reference characteristic of the gain of the vehicle's acceleration 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 threshold, a driving assistance method is provided in which the gain is set to be smaller than the gain of the reference characteristic, and a driving assistance device that performs this driving assistance method is provided. This makes it possible to suppress unnecessary acceleration of the vehicle in driving scenes in which slow driving is required. In particular, by setting a small gain of acceleration with respect to the amount of depression when the amount of depression of the pedal is relatively small, acceleration when the vehicle starts moving from a standstill can be suppressed, which can prevent a vehicle driven by a driver with low pedal operation accuracy (e.g., an elderly person) from coming into contact with an obstacle when starting (especially when the amount of depression is relatively small).

[0073] In the driving assistance method and driving assistance device of this embodiment, the predetermined scene includes a scene in which the vehicle starts moving from a stationary state. This ensures that acceleration when the vehicle starts moving is reliably suppressed.

[0074] In the driving assistance method and driving assistance device of this embodiment, the predetermined scene includes a scene in which the vehicle is traveling at a speed below a predetermined speed. This makes it possible to further suppress unnecessary acceleration of the vehicle in driving scenes in which slow speed is required.

[0075] In the driving assistance method and driving assistance device of this embodiment, the predetermined scene includes a scene in which the vehicle may come to a stop before a predetermined time has elapsed after starting from a standstill. This ensures that the acceleration of the vehicle is reliably suppressed in the first scene, the second scene, the fourth scene, and so on.

[0076] In the driving assistance method and driving assistance device of this embodiment, the gain is set to be smaller than the gain of the reference characteristic in at least one of the cases in which the amount of depression of the accelerator pedal increases and the amount of depression of the brake pedal decreases. This ensures that acceleration is suppressed when the vehicle is accelerating.

[0077] In the driving assistance method and driving assistance device of this embodiment, the gain when the amount of depression of the brake pedal decreases is set to be greater than the gain when the amount of depression of the accelerator pedal increases. This ensures that acceleration is reliably suppressed when the vehicle is accelerating.

[0078] In the driving assistance method and driving assistance device of this embodiment, when the amount of depression of the brake pedal increases, the gain is set to be smaller than the gain of the reference characteristic. This makes it possible to suppress the vehicle from suddenly decelerating (or suddenly stopping).

[0079] In the driving assistance method and driving assistance device of this embodiment, when the vehicle is driven in one-pedal mode, where acceleration and deceleration of the vehicle are controlled solely by operating the accelerator pedal, the gain is set to be smaller than the gain of the reference characteristic when the amount of depression of the accelerator pedal decreases. This enables smooth deceleration when driving in one-pedal mode.

[0080] In the driving assistance method and driving assistance device of this embodiment, the predetermined scene includes a scene in which the vehicle, which is traveling at a predetermined speed, comes to a stop. This makes it possible to further suppress unnecessary acceleration of the vehicle in driving scenes in which slow speed is required.

[0081] In the driving assistance method and driving assistance device of this embodiment, the gain when the vehicle's shift position is in the reverse range is set to be smaller than the gain when the shift position is in the drive range. This makes it possible to suppress the vehicle from accelerating rapidly when it is reversing.

[0082] 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 process of setting a gain smaller than the gain of the reference characteristic. This allows the driver or a dealer's mechanic to select the vehicle's acceleration characteristics according to the driver's attributes.

[0083] In the driving assistance method and driving assistance device of this embodiment, the driver of the vehicle is notified that the gain set to be smaller than the gain of the reference characteristic. This prevents the driver from feeling discomfort or unease due to the acceleration characteristics being changed against their will.

[0084] 10...Driving support 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 support device, 20a...Switch, 21...Determination unit, 22...Setting unit, A1, A2, A3, A4...Accelerometer, B1, B2, B3, B4...Reference acceleration, C...Intersection, L1, L2...Lane, H...Stop line, P1, P2, P3...Position, Px...Destination, V...Vehicle, X1, X2, X3, X4, X5...Pedaling ratio

Claims

1. A driving assistance method performed by a vehicle driving assistance device, wherein the driving assistance device has a preset reference characteristic of the gain of the vehicle's acceleration with respect to the amount of depression of at least one of the vehicle's accelerator pedal and brake pedal, 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 threshold, the driving assistance method sets the gain to be smaller than the gain of the reference characteristic.

2. The driving assistance method according to claim 1, wherein the predetermined scene includes a scene in which the vehicle starts moving from a stationary state.

3. The driving assistance method according to claim 1 or 2, wherein the predetermined scene includes a scene in which the vehicle is traveling at a speed less than a predetermined speed.

4. The driving assistance method according to any one of claims 1 to 3, wherein the predetermined scene includes a scene in which the vehicle may come to a stop before a predetermined time has elapsed after it has started moving from a stationary state.

5. The driving assistance method according to any one of claims 1 to 4, wherein the driving assistance device sets the gain to be smaller than the gain of the reference characteristic in at least one of the cases in which the amount of depression of the accelerator pedal increases and the amount of depression of the brake pedal decreases.

6. The driving assistance method according to any one of claims 1 to 5, wherein the driving assistance device sets the gain when the amount of depression of the brake pedal decreases to be greater than the gain when the amount of depression of the accelerator pedal increases.

7. The driving assistance method according to any one of claims 1 to 6, wherein the driving assistance device sets the gain to be smaller than the gain of the reference characteristic when the amount of depression of the brake pedal increases.

8. The driving assistance method according to any one of claims 1 to 7, wherein when the vehicle is driving in a one-pedal mode in which the acceleration and deceleration of the vehicle are controlled by operating only the accelerator pedal, the amount of depression of the accelerator pedal decreases, and the driving assistance device sets the gain to be smaller than the gain of the reference characteristic.

9. The driving assistance method according to any one of claims 1 to 8, wherein the predetermined scene includes a scene in which the vehicle traveling at a predetermined speed comes to a stop.

10. The driving assistance method according to any one of claims 1 to 9, wherein the driving assistance device sets the gain when the vehicle's shift position is in the reverse range to be smaller than the gain when the shift position is in the drive range.

11. The driving assistance method according to any one of claims 1 to 10, wherein the vehicle is provided with a switch for selecting whether or not to perform a setting process for a gain smaller than the gain of the reference characteristic.

12. The driving assistance method according to any one of claims 1 to 11, wherein the driving assistance device notifies the driver of the vehicle that the gain set is smaller than the gain of the reference characteristic.

13. A driving assistance device comprising a setting unit that has a preset reference characteristic for the gain of the vehicle's acceleration in relation to the amount of depression of at least one of the vehicle's accelerator pedal and brake pedal, and when it is determined that the driving scene of the vehicle is a predetermined scene in which the vehicle is moving slowly, and the amount of depression is less than a predetermined threshold, the setting unit sets the gain to be smaller than the gain of the reference characteristic.

Images