Operation support system, operation support program, operation support method

Abstract

To provide an operation support system which is effective for collision avoidance between a vehicle and a target.SOLUTION: A processor of an operation support system for supporting collision avoidance from a target in operation of a host vehicle executes: monitoring collision risk between the host vehicle and the target; and controlling a travel resistance Fr to be applied to the host vehicle so as to compensate an actual brake force Fa in response to such prediction that the actual brake force Fa, that can be applied to a wheel from a brake actuator falls outside a required range ΔF for collision avoidance, in the host vehicle in high-risk situations such that the collision risk increases to a collision avoidance level that requires the host vehicle to avoid collision.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a driving assistance technology that assists driving of a vehicle. [Background technology]

[0002] The technology disclosed in Patent Document 1 controls the regenerative braking force supplemented by the electric motor when it is determined that there is a possibility that the vehicle will collide with an obstacle, without taking into account the maximum torque limit value under normal conditions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-216771 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the maximum torque limit value of the electric motor is not taken into consideration, as in the technology disclosed in Patent Document 1, the magnitude of the regenerative braking force that can be generated is limited due to, for example, the state of charge of the battery connected to the electric motor, etc. Therefore, there is a concern that this may not be effective in ensuring the braking necessary to avoid a collision, depending on, for example, the degree of urgency or road surface conditions.

[0005] An object of the present disclosure is to provide a driving assistance system that is effective for avoiding a collision between a vehicle and a target. Another object of the present disclosure is to provide a driving assistance program that is effective for avoiding a collision between a vehicle and a target. Yet another object of the present disclosure is to provide a driving assistance method that is effective for avoiding a collision between a vehicle and a target. [Means for solving the problem]

[0006] The technical means of the present disclosure for solving the problems will be described below. Note that the claims and the reference characters in parentheses in this section indicate the correspondence with the specific means described in the embodiments described later in detail, and do not limit the technical scope of the present disclosure.

[0007] A first aspect of the present disclosure is A driving assistance system having a processor (12) for assisting a host vehicle (2) in avoiding a collision with a target (3), the system comprising: The processor monitoring a host vehicle's risk of collision with a target; In response to prediction that the actual braking force (Fa) that can be applied to the wheels (20) from the brake actuator (44) in the host vehicle in an increased risk scene where the collision risk has increased to a collision avoidance level that requires the host vehicle to avoid collision, will fall outside the required range (ΔF) for collision avoidance, the running resistance (Fr) applied to the host vehicle is controlled to complement the actual braking force.

[0008] A second aspect of the present disclosure is A driving assistance program stored in a storage medium (10) for assisting a host vehicle (2) in avoiding a collision with a target (3), the driving assistance program including instructions to be executed by a processor (12), the program comprising: monitoring a host vehicle's risk of collision with a target; In response to the actual braking force (Fa) that can be applied to the wheels (20) from the brake actuator (44) in the host vehicle in an increased risk scene where the collision risk has increased to a collision avoidance level that requires the host vehicle to avoid the collision, being predicted to fall outside the required range (ΔF) for collision avoidance, the running resistance (Fr) applied to the host vehicle is controlled to complement the actual braking force.

[0009] A third aspect of the present disclosure is A driving assistance method executed by a processor (12) for assisting a host vehicle (2) in avoiding a collision with a target (3), comprising: monitoring a host vehicle's risk of collision with a target; In a host vehicle in an increased risk scene where the collision risk has increased to a collision avoidance level requiring the host vehicle to avoid collision, the actual braking force (Fa) that can be applied to the wheels (20) from the brake actuator (44) is predicted to decrease outside a required range (ΔF) for collision avoidance, and in response to this, the running resistance (Fr) applied to the host vehicle is controlled to complement the actual braking force.

[0010] In these first to third aspects, the actual braking force that can be applied to the wheels from the brake actuator of the host vehicle in an increased risk scene where the monitored collision risk with the target increases is predicted. Therefore, according to the first to third aspects, in response to a prediction that the actual braking force that can be applied will fall outside the required range for avoiding a collision with the target, a running resistance controlled to complement the actual braking force is applied to the host vehicle. In this way, the braking required to avoid a collision with the target in the host vehicle can be ensured by the combined effect of the actual braking force and the running resistance. Therefore, driving assistance that is effective for avoiding a collision with the target in the host vehicle can be provided. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a block diagram showing a physical configuration of a driving assistance system according to a first embodiment. [Figure 2] FIG. 2 is a schematic diagram showing a running state of a host vehicle to which the first embodiment is applied. [Figure 3] FIG. 1 is a block diagram showing a functional configuration of a driving assistance system according to a first embodiment. [Figure 4] 4 is a flowchart showing a driving assistance flow according to the first embodiment. [Figure 5] 4 is a flowchart showing an operation control subroutine according to the first embodiment. [Figure 6] 10 is a flowchart showing an operation control subroutine according to a second embodiment. [Figure 7] FIG. 10 is a schematic diagram showing a running state of a host vehicle to which a second embodiment is applied. [Figure 8] 10 is a flowchart showing a driving assistance flow according to a third embodiment. [Figure 9] FIG. 11 is a schematic diagram showing a running state of a host vehicle to which a third embodiment is applied. [Figure 10] 10 is a flowchart showing an operation control subroutine according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, multiple embodiments of the present disclosure will be described with reference to the drawings. Note that corresponding components in each embodiment are designated by the same reference numerals, and redundant description may be omitted. Furthermore, when only a portion of the configuration is described in each embodiment, the configuration of another previously described embodiment may be applied to the remaining portions of the configuration. Furthermore, in addition to the combinations of configurations explicitly stated in the description of each embodiment, configurations of multiple embodiments may be partially combined together even if not explicitly stated, provided that there is no particular problem with the combination.

[0013] (First embodiment) A driving assistance system 1 of the first embodiment shown in FIG. 1 assists in driving a host vehicle 2. At least a part of the driving assistance system 1 is mounted on the host vehicle 2. The host vehicle 2 to which the driving assistance system 1 is applied may be capable of achieving a level of automated driving defined in, for example, SAE J3016, in which, along with automated driving tasks, manual driving assistance tasks exist that assist an operator in performing manual driving operations. Such a host vehicle 2 is a road user, such as an automobile or truck, and may also be referred to as an ego-vehicle. As described above, the driving assistance system 1, as the operator of the host vehicle 2, provides driving assistance to a driver who is aboard the host vehicle 2 and is capable of performing manual driving operations.

[0014] As shown in FIG. 2, the driving environment in which the host vehicle 2 travels includes at least one of other road users, obstacles, and structures as targets 3 other than the host vehicle 2. Other road users include non-vulnerable road users and vulnerable road users. Non-vulnerable road users are at least one type of moving body with a human on board, such as a car, truck, motorcycle, or bicycle. Vulnerable users are, for example, pedestrians. Obstacles include at least one type of construction signboard, work signboard, or fallen object. Structures include at least one type of building, road structure, traffic light, or road sign.

[0015] 1, a host vehicle 2 is equipped with an actuator system 4, a sensor system 5, a communication system 6, a map database (DB) 7, and an information presentation system 8, along with at least a part of a driving assistance system 1. However, FIG. 1 representatively shows an example in which the entire driving assistance system 1 implemented in the form of a processing circuit (e.g., a processing ECU) or a semiconductor device (e.g., a semiconductor chip) is equipped in the host vehicle 2.

[0016] The actuator system 4 is configured to be able to control the driving behavior of the host vehicle 2 based on control commands from the driving assistance system 1. Here, as specifically shown in Fig. 3, the actuator system 4 includes at least one type of power train actuator 40, such as an internal combustion engine or a motor-generator-motor. The actuator system 4 also includes at least one type of steering actuator 42, such as a power steering unit. The actuator system 4 also includes at least one type of braking actuator 44, such as a brake unit.

[0017] 2, the host vehicle 2 has front wheels 20fl, 20fr and rear wheels 20rl, 20rr as its multiple wheels 20. The brake actuator 44 adjusts the braking force applied to the host vehicle 2 independently of the braking force applied to the front wheels 20fl, 20fr and the braking force applied to the rear wheels 20rl, 20rr. This allows the host vehicle 2 to control the left-right and front-rear distribution of braking force.

[0018] On the other hand, the steering actuator 42 adjusts at least one of the steering angle common to the front wheels 20fl, 20fr and the steering angle common to the rear wheels 20rl, 20rr as the steering angle to be applied to the host vehicle 2. The common steering angle of the front wheels 20fl, 20fr and the common steering angle of the rear wheels 20rl, 20rr may be adjusted independently of each other, and in this case, the host vehicle 2 can control the front / rear distribution of these common steering angles.

[0019] 1 senses the external and internal environments of the host vehicle 2 to obtain sensing information that can be used in the driving assistance system 1. To this end, the sensor system 5 includes an external sensor 50 and an internal sensor 52.

[0020] The external sensor 50 senses targets 3 that exist in the external world of the host vehicle 2. The target sensing type external sensor 50 is at least one type of sensor selected from the group consisting of an image sensor (i.e., an on-board camera), a LiDAR (light detection and ranging / laser imaging detection and ranging), a laser sensor, a millimeter wave sensor, and a sonar sensor. The target sensing type external sensor 50 may be implemented by combining multiple types of sensors so as to be capable of sensing the front, side, and rear directions of the host vehicle 2.

[0021] The internal sensor 52 senses a specific physical quantity of motion related to vehicle motion in the internal environment of the host vehicle 2. The internal sensor 52 of the motion sensing type is at least one of, for example, a speed sensor, an acceleration sensor, a gyro sensor, etc. The internal sensor 52 may sense the operation or state of occupants, including the driver, riding in the internal environment of the host vehicle 2. The internal sensor 52 of the occupant sensing type is at least one of, for example, an accelerator pedal sensor, a steering angle sensor, a steering torque sensor, a brake pedal sensor, a shift sensor, an occupant camera, a steering switch, a biosensor, a seating sensor, an in-vehicle device switch, etc.

[0022] The communication system 6 acquires communication information usable in the driving assistance system 1 via wireless communication. The communication system 6 may receive positioning signals from satellites of a global navigation satellite system (GNSS) present in the external world of the host vehicle 2. The positioning type communication system 6 is, for example, a GNSS receiver. The communication system 6 may transmit and receive communication signals to and from a V2X system present in the external world of the host vehicle 2. The V2X communication type communication system 6 is, for example, at least one of a dedicated short range communications (DSRC) communication device and a cellular V2X (C-V2X) communication device. The communication system 6 may transmit and receive communication signals to and from a mobile terminal present in the internal world of the host vehicle 2. The terminal communication type communication system 6 is, for example, at least one of a Bluetooth (registered trademark) device, a Wi-Fi (registered trademark) device, an infrared communication device, etc.

[0023] The map DB 7 stores map information that can be used in the driving assistance system 1. The map DB 7 includes at least one type of non-transitory tangible storage medium, such as a semiconductor memory, a magnetic medium, or an optical medium. The map DB 7 may be a DB for a locator that estimates the self-position of the host vehicle 2. The map DB may be a DB for a navigation unit that navigates the driving route of the host vehicle 2. The map DB 7 may be constructed by combining multiple types of DBs.

[0024] The map DB 7 acquires and stores the latest map information, for example, through V2X communication with an external center via the communication system 6. The map information is converted into two-dimensional or three-dimensional data representing the external environment in which the host vehicle 2 is traveling. Digital data of a high-precision map may be used as the three-dimensional map information. The map information includes road information representing at least one of the following: the position, shape, and road surface condition of road structures. The map information may also include structure information representing at least one of the following: the position, shape, and other information of buildings and traffic lights facing the road. The map information may also include marking information representing at least one of the following: the position, shape, and other information of signs and lane markings attached to the road.

[0025] The information presentation system 8 presents notification information to occupants, including the driver, of the host vehicle 2. The information presentation system 8 presents notification information by stimulating the vision of the occupants in the host vehicle 2. The information presentation system 8 of the visual information presentation type is, for example, at least one of an in-vehicle monitor, a head-up display (HUD), a combination meter, a navigation unit, and an illumination unit. The information presentation system 8 may present notification information by stimulating the auditory sense of the occupants. The information presentation system 8 of the auditory information presentation type is, for example, at least one of a speaker, a buzzer, and a vibration unit. The information presentation system 8 may present notification information by stimulating the cutaneous sense of the occupants. The information presentation system 8 of the cutaneous sense information presentation type is, for example, at least one of a vibration unit, a reaction force unit, and an air conditioning unit.

[0026] The driving assistance system 1 is connected to an actuator system 4, a sensor system 5, a communication system 6, a map DB 7, and an information presentation system 8 via at least one of, for example, a LAN (local area network), a wire harness, an internal bus, or a wireless communication line. The driving assistance system 1 is configured to include at least one dedicated computer.

[0027] The dedicated computer constituting the driving assistance system 1 may be an integrated ECU (electronic control unit) that integrates the driving control of the host vehicle 2. The dedicated computer constituting the driving assistance system 1 may be a sensing ECU that processes sensing information in the driving control of the host vehicle 2. The dedicated computer constituting the driving assistance system 1 may be a recognition ECU that recognizes the external world in the driving control of the host vehicle 2. The dedicated computer constituting the driving assistance system 1 may be a locator ECU that estimates the self-position of the host vehicle 2.

[0028] The dedicated computer constituting the driving assistance system 1 may be a planning ECU that plans driving control of the host vehicle 2. The dedicated computer constituting the driving assistance system 1 may be a navigation ECU that navigates a driving route in driving control of the host vehicle 2. The dedicated computer constituting the driving assistance system 1 may be an actuator ECU that controls the actuator system 4 as part of driving control of the host vehicle 2.

[0029] The dedicated computer constituting the driving assistance system 1 may be an information management ECU that controls the information presentation system 8 as part of driving control of the host vehicle 2. The dedicated computer constituting the driving assistance system 1 may also be at least one external computer that constitutes, for example, an external center or a mobile terminal that can communicate via the communication system 6.

[0030] The dedicated computer constituting the driving assistance system 1 has at least one memory 10 and one processor 12. The memory 10 is at least one type of non-transitory tangible storage medium, such as a semiconductor memory, a magnetic medium, or an optical medium, that non-temporarily stores computer-readable programs, data, etc. The processor 12 includes at least one type of core, such as a central processing unit (CPU), a graphics processing unit (GPU), or a reduced instruction set computer (RISC)-CPU.

[0031] The processor 12 executes a plurality of instructions included in a driving assistance program stored as software in the memory 10. In this way, the driving assistance system 1 constructs a plurality of functional blocks for performing driving assistance processing for the host vehicle 2. The plurality of functional blocks constructed by the driving assistance system 1 in this way include a monitoring block 100 and a control block 120 shown in FIG. 3.

[0032] The monitoring block 100 acquires sensing information from the sensor system 5. The monitoring block 100 acquires communication information from the communication system 6. The monitoring block 100 acquires map information from the map DB 7. The monitoring block 100 acquires data of past control commands to the host vehicle 2 from the control block 120. The monitoring block 100 processes this acquired information and data individually and then fuses them to generate recognition data that recognizes the external and internal environments of the host vehicle 2. In this way, the recognition data generated by the monitoring block 100 represents the state of the external and internal environments that are monitored for each driving scene in which the host vehicle 2 travels.

[0033] Specifically, the monitoring block 100 generates recognition data by localization that recognizes the self-state of the host vehicle 2. The recognition data regarding the self-state may represent at least one type of physical quantity of motion, such as position, velocity, acceleration, jerk, yaw rate, yaw angle, pitch angle, and roll angle, which appear in the host vehicle 2 in accordance with a control command from the control block 120, which will be described in detail later. The monitoring block 100 generates recognition data by recognizing a target 3 in the external world of the host vehicle 2. The recognition data regarding the target 3 may represent at least one type of physical quantity of motion, such as separation distance, direction of motion, relative velocity, relative acceleration, and time to collision (TTC) with the host vehicle 2.

[0034] The control block 120 acquires recognition data from the monitoring block 100. The control block 120 acquires data of past control commands to the host vehicle 2 by reading it from the memory 10. Based on this acquired data, the control block 120 plans a target driving trajectory Td (see FIG. 2) for the future driving of the host vehicle 2. The driving trajectory Td specifies the time-series changes for each control cycle expected in the future, with respect to the motion parameters that are the target state of the host vehicle 2. Specifically, the driving trajectory Td may represent the position coordinates for each control cycle of the trajectory that the host vehicle 2 is to follow in the future. Furthermore, the driving trajectory Td may represent at least one type of motion physical quantity, such as speed, acceleration, jerk, yaw rate, yaw angle, pitch angle, and roll angle, as the motion parameters to be displayed for each control cycle on the trajectory.

[0035] The control block 120 generates a control command for controlling the driving behavior of the host vehicle 2 according to the planned driving trajectory Td. At this time, the control command is generated to be sent to the actuator system 4 so as to control a driving task corresponding to an autonomous driving level adjusted according to the driving scene, out of an autonomous driving task and a manual driving assistance task in the host vehicle 2. The control command generated in this manner is stored in the memory 10.

[0036] Examples of driving tasks corresponding to the autonomous driving level include adaptive cruise control (ACC), autonomous emergency braking (AEB), and lane keeping assist (LKA). Therefore, adjustment of the autonomous driving level may include a handover in which the driving task is transferred between the driving assistance system 1 and the driver by transitioning the driving mode between the autonomous driving task and the manual driving assistance task. Such a handover is realized at least at one of the following times: a driver's request for handover, a move toward or away from the autonomous driving operational design domain (ODD), and a required time for a minimum risk maneuver (MRM).

[0037] The driving assistance method in which the driving assistance system 1 performs driving assistance processing for the host vehicle 2 through cooperation of these blocks 100 and 120 is executed according to the driving assistance flow shown in Fig. 4. This driving assistance flow is executed repeatedly while the host vehicle 2 is running. Note that each "S" in this driving assistance flow represents a step executed by multiple commands included in the driving assistance program.

[0038] In S10, the monitoring block 100 monitors the collision risk of the host vehicle 2 with the target 3, and determines whether a collision avoidance condition has been met, which requires the host vehicle 2 to avoid a collision with the target 3 in future travel. The collision avoidance condition is met when the collision risk between the host vehicle 2 and the target 3 increases to a collision avoidance level that requires the host vehicle 2 to avoid a collision.

[0039] The determination of whether the collision risk has reached the collision avoidance level in S10 is based on the recognition data. Therefore, the collision risk may be determined to have reached the collision avoidance level when the TTC is equal to or less than a threshold time (e.g., 2 seconds). In addition to the TTC requirement, the collision risk may also be determined to have reached the collision avoidance level when the probability of collision avoidance, for example, by changing lanes, is equal to or exceeds a threshold.

[0040] If the collision risk has not reached the collision avoidance level in S10, and the collision avoidance condition is not established, resulting in a negative determination, the current driving assistance flow ends. On the other hand, if the collision risk has reached the collision avoidance level in S10, and the collision avoidance condition is established, resulting in a positive determination, the current driving scene is considered to be an elevated risk scene, and the current driving assistance flow proceeds to S20.

[0041] In S20, the control block 120 plans a driving trajectory Td, which is a tracing target for future travel of the host vehicle 2, to avoid a collision between the host vehicle 2 and the target 3 in an elevated-risk scene. At this time, the driving trajectory Td is planned so as to prescribe, for each control cycle, a time-series change in at least one type of motion physical quantity among speed, acceleration, jerk, yaw rate, yaw angle, pitch angle, and roll angle, in addition to a trajectory that is a time-series change in position coordinates, as a motion parameter to be targeted for future travel of the host vehicle 2. As a result, the driving trajectory Td (see FIG. 2) of the first embodiment becomes a trajectory for avoiding a collision solely by the braking force of the wheels 20, without substantially coordinating with the steering angle of the wheels 20 of the host vehicle 2.

[0042] In the next S30, the control block 120 executes a driving control subroutine for generating a control command to the actuator system 4 in an increased-risk scenario in accordance with each motion parameter represented by the driving trajectory Td planned in S20. Therefore, in S300 of the driving control subroutine shown in Fig. 5, the control block 120 sets a required range ΔF of the braking force required of the host vehicle 2 in an increased-risk scenario in accordance with each motion parameter represented by the driving trajectory Td. At this time, the required range ΔF is set to a range exceeding or exceeding a lower limit value for each of the front wheels 20fl, 20fr and the rear wheels 20rl, 20rr as the braking force required of the brake actuator 44 to apply to each of the front wheels 20fl, 20fr and the rear wheels 20rl, 20rr in order to avoid a collision according to the driving trajectory Td.

[0043] In S310, which follows the driving control subroutine, the control block 120 predicts the actual braking force Fa that can be applied to the host vehicle 2 in the increased-risk scenario based on the driving characteristics estimated for the host vehicle 2. At this time, the actual braking force Fa is predicted to be the maximum allowable value for each wheel 20 as the braking force that can be applied from the brake actuator 44 to each of the front wheels 20fl, 20fr and the rear wheels 20rl, 20rr in the host vehicle 2. Therefore, the driving characteristic of the host vehicle 2 estimated to predict the actual braking force Fa may be the response speed of the brake actuator 44. The driving characteristic of the host vehicle 2 estimated to predict the actual braking force Fa may be a limit value for the longitudinal acceleration and / or longitudinal jerk (jerk) of the host vehicle 2. The driving characteristic of the host vehicle 2 estimated to predict the actual braking force Fa may be the ground contact load of the front wheels 20fl, 20fr and the rear wheels 20rl, 20rr. The running characteristics of the host vehicle 2 estimated to predict the actual braking force Fa may be the gradient and / or skid resistance of the road surface.

[0044] In S320, which follows the driving control subroutine, the control block 120 determines whether the actual braking force Fa predicted in S310 for the host vehicle 2 in the increased-risk scenario has fallen outside the required range ΔF set in S300 to avoid a collision. The comparison of the actual braking force Fa with the required range ΔF may be performed for each of the front wheels 20fl, 20fr and the rear wheels 20rl, 20rr. In this case, if the actual braking force Fa for at least one wheel 20 among the front wheels 20fl, 20fr and the rear wheels 20rl, 20rr is outside the required range ΔF, i.e., has fallen below or below the lower limit of the range ΔF, a positive determination is made. On the other hand, if the actual braking force Fa for all wheels 20, including the front wheels 20fl, 20fr and the rear wheels 20rl, 20rr, is within the required range ΔF or exceeds or exceeds the lower limit of the range ΔF, a negative determination is made.

[0045] However, the comparison of the actual braking forces Fa with the required range ΔF may be performed for the front wheels 20fl, 20fr and the rear wheels 20rl, 20rr combined. In this case, if the sum of the actual braking forces Fa predicted for the front wheels 20fl, 20fr and the rear wheels 20rl, 20rr falls below or equal to the integrated value of the lower limit values ​​of the required ranges ΔF set for the front wheels 20fl, 20fr and the rear wheels 20rl, 20rr, a positive determination is made. On the other hand, if the sum of the actual braking forces Fa exceeds or is equal to or greater than the integrated value of the lower limit values ​​of the required ranges ΔF, a negative determination is made.

[0046] If a positive determination is made in S320 in response to the actual braking force Fa decreasing outside the required range ΔF, the driving control subroutine proceeds to S330. In S330, the control block 120 generates a control command for the brake actuator 44 so as to apply to the host vehicle 2 in the increased-risk scenario an amount of the actual braking force Fa predicted when the actual vehicle deviates from the required range ΔF for avoiding a collision with the target 3. At the same time, in S330, the control block 120 controls the running resistance Fr acting on the host vehicle 2 in the increased-risk scenario so as to complement the actual braking force Fa predicted to decrease outside the required range ΔF. Particularly in S330 of the first embodiment, the running resistance Fr that complements the actual braking force Fa predicted to decrease outside the required range ΔF is applied to the host vehicle 2 by controlling to increase the road resistance Frr that the wheels 20 of the host vehicle 2 receive from the road surface.

[0047] In S330, the control to increase the road resistance Frr, which becomes the running resistance Fr, may be achieved by adjusting the air pressure in the tire of at least one wheel 20 among the front wheels 20fl, 20fr and rear wheels 20rl, 20rr of the host vehicle 2. In this case, the actual braking force Fa may be supplemented by adjusting the air pressure in the target wheel 20 to be higher or lower than before the affirmative determination in S320 so as to increase the road resistance Frr by an amount corresponding to the deviation between the lower limit value of the required range ΔF and the actual braking force Fa. Therefore, the air pressure may be adjusted to be higher or lower by generating a control command to an electric air valve or the like provided on each wheel of the front wheels 20fl, 20fr and the rear wheels 20rl, 20rr.

[0048] In S330, the control to increase road resistance Frr, which becomes running resistance Fr, may be achieved by increasing or adjusting the contact pressure between at least one wheel 20 of the front wheels 20fl, 20fr and rear wheels 20rl, 20rr of the host vehicle 2 and the road surface. In this case, the actual braking force Fa may be supplemented by increasing the contact pressure at the target wheel 20 relative to the pressure before the affirmative determination in S320 so as to increase road resistance Frr by an amount corresponding to the deviation between the lower limit of the required range ΔF and the actual braking force Fa. Therefore, the contact pressure may be increased or adjusted by generating a control command to an active suspension or the like that elastically supports each shaft of the front wheels 20fl, 20fr and the rear wheels 20rl, 20rr. The contact pressure may be increased or adjusted by, for example, generating a control command to an electric air valve or the like provided on each wheel to increase or decrease the air pressure of the front wheels 20fl, 20fr and the rear wheels 20rl, 20rr.

[0049] In S330, the control to increase the road resistance Frr, which becomes the running resistance Fr, may be realized by adjusting the viscosity of the contact surface with the road surface of at least one wheel 20 of the front wheels 20fl, 20fr and rear wheels 20rl, 20rr of the host vehicle 2. In this case, the actual braking force Fa may be supplemented by adjusting the viscosity of the contact surface of the target wheel 20 to be more viscous than before the affirmative determination in S320 so that the road resistance Frr is increased by an amount corresponding to the deviation between the lower limit value of the required range ΔF and the actual braking force Fa. Therefore, the viscosity of the contact surface may be adjusted to be more viscous by generating a control command to an injector or the like that injects a thickener onto the circumferential surface of the front wheels 20fl, 20fr and rear wheels 20rl, 20rr, for example.

[0050] The adjustment of the contact pressure, air pressure, and viscosity to increase the resistances Fr and Frr may be performed by any one of them alone or by a combination of at least two of them. In either case, the adjustment of the contact pressure, air pressure, and viscosity may be performed for at least one wheel 20 among the front wheels 20fl and 20fr and the rear wheels 20rl and 20rr whose actual braking force Fa has fallen outside the required range ΔF. However, in either case, the adjustment of the contact pressure, air pressure, and viscosity may be performed so as to increase the road surface resistance Frr by an amount corresponding to the deviation between the sum of the actual braking forces Fa of the front wheels 20fl and 20fr and the rear wheels 20rl and 20rr and the integrated value between the lower limit values ​​of the required range ΔF.

[0051] In S330, the control block 120 may notify the driver of an emergency braking state for collision avoidance by generating a control command to the information presentation system 8 in association with braking application that complements the actual braking force Fa with the running resistance Fr. In S330, the control block 120 may notify the driver of the braking state due to the complementation by generating a control command to the information presentation system 8 in association with braking application that complements the actual braking force Fa with the running resistance Fr. The above S330 continues until collision avoidance is completed, and the current execution of the driving assistance flow including the driving control subroutine ends upon completion.

[0052] If a negative determination is made in S320, the driving control subroutine proceeds to S340. In S340, the control block 120 generates a control command for the brake actuator 44 to apply a braking force within the required range ΔF set in S300 to the host vehicle 2 in the increased-risk scene. At this time, a control command for the information presentation system 8 may be generated in conjunction with braking, thereby informing the driver of an emergency braking state for collision avoidance. S340 continues until collision avoidance is completed, and the current execution of the driving assistance flow including the driving control subroutine ends upon completion of the collision avoidance.

[0053] (Action and effect) The effects of the first embodiment described above will be explained below.

[0054] In the first embodiment, an actual braking force Fa that can be applied from the brake actuator 44 to the wheels 20 of the host vehicle 2 in an increased-risk scene where the risk of collision monitored with the target 3 is increasing is predicted. Therefore, according to the first embodiment, in response to a prediction that the applicable actual braking force Fa will fall outside the required range ΔF for avoiding a collision with the target 3, a running resistance Fr controlled to complement the actual braking force Fa is applied to the host vehicle 2. In this way, the braking required for the host vehicle 2 to avoid a collision with the target 3 can be ensured by the combined effect of the actual braking force Fa and the running resistance Fr. Therefore, it is possible to provide driving assistance that is effective for the host vehicle 2 to avoid a collision with the target 3.

[0055] According to the first embodiment, by controlling the road resistance Frr that the wheels 20 of the host vehicle 2 receive from the road surface, a running resistance Fr that complements the actual braking force Fa that is predicted to decrease outside the required range ΔF is applied to the host vehicle 2. This makes it possible to ensure the braking required to avoid a collision with the target 3 in the host vehicle 2 by the combined effect of the actual braking force Fa and the road resistance Frr, thereby providing driving assistance that is effective in avoiding the collision.

[0056] According to the first embodiment, the road resistance Frr as the running resistance Fr may be controlled to increase by adjusting the air pressure in the wheels 20 of the host vehicle 2 to increase or decrease it. Such adjustment of the air pressure to increase or decrease it makes it possible to timely apply the road resistance Frr that can complement the actual braking force Fa to the host vehicle 2 in which a decrease in the actual braking force Fa is predicted in order to realize the braking necessary to avoid a collision with the target 3, thereby increasing the reliability of driving assistance that is effective in avoiding the collision.

[0057] According to the first embodiment, the road surface resistance Frr as the running resistance Fr may be controlled to increase by adjusting the contact pressure between the wheels 20 of the host vehicle 2 and the road surface on which the vehicle is traveling. Adjusting the contact pressure increase in this way makes it possible to timely apply the road surface resistance Frr, which can complement the actual braking force Fa, to the host vehicle 2 in which a decrease in the actual braking force Fa is predicted in order to achieve the braking necessary to avoid a collision with the target 3, and thereby increase the reliability of driving assistance that is effective in avoiding the collision.

[0058] According to the first embodiment, the road surface resistance Frr as the running resistance Fr may be controlled to increase by adjusting the viscosity of the contact surface between the wheels 20 of the host vehicle 2 and the road surface on which the host vehicle 2 is traveling. Such adjustment of the viscosity of the contact surface applies to the host vehicle 2 for which a decrease in the actual braking force Fa is predicted, a road surface resistance Frr of a magnitude that can complement the actual braking force Fa in order to realize the braking necessary to avoid a collision with the target 3, thereby making it possible to increase the reliability of driving assistance that is effective in avoiding the collision.

[0059] Second Embodiment The second embodiment is a modification of the first embodiment. As shown in Fig. 6, in the operation control subroutine of the second embodiment, S2330 is executed instead of S330.

[0060] In S2330, which controls the running resistance Fr so as to complement the outside of the required range ΔF and the predicted actual braking force Fa, the control block 120 executes control to increase the air resistance Fra that the vehicle body 22 of the host vehicle 2 receives from the outside air as shown in Fig. 7, as the complementary control of the running resistance Fr. Therefore, the control to increase the air resistance Fra, which becomes the running resistance Fr, may be realized by adjusting the opening of a window in the vehicle body 22 of the host vehicle 2, for example, by generating a control command to power windows or the like provided on both sides of the vehicle body 22.

[0061] In such window opening adjustment, at least a predetermined rear side window out of the front and rear side windows may be targeted for opening. In the window opening adjustment, the side window targeted for opening may be limited to the side window located immediately above at least one wheel 20 of the front wheels 20fl, 20fr and the rear wheels 20rl, 20rr whose actual braking force Fa has fallen outside the required range ΔF. In the window opening adjustment, the side window targeted for opening may be limited to the side window located immediately to the side of an empty seat in the host vehicle 2 where no occupant is seated.

[0062] As described above, according to the second embodiment, by controlling the host vehicle 2 to increase the air resistance Fra that the vehicle body 22 receives from the outside air, a running resistance Fr that complements the actual braking force Fa that is predicted to decrease outside the required range ΔF is applied to the host vehicle 2. This makes it possible to ensure the braking required to avoid a collision with the target 3 in the host vehicle 2 by the combined effect of the actual braking force Fa and the air resistance Fra, thereby providing driving assistance that is effective in avoiding the collision.

[0063] Furthermore, according to the second embodiment, the air resistance Fra as the running resistance Fr may be controlled to increase by adjusting the opening of a window in the vehicle body 22 of the host vehicle 2. Such window opening adjustment provides the air resistance Fra that can supplement the actual braking force Fa to achieve the braking required to avoid a collision with the target 3 by effectively utilizing a general-purpose configuration in the host vehicle 2 in which a decrease in the actual braking force Fa is predicted, thereby making it possible to suppress an increase in costs required to achieve driving assistance that is effective in avoiding the collision.

[0064] (Third embodiment) The third embodiment is a modification of the first embodiment. As shown in Fig. 8, in the driving assistance flow of the third embodiment, S3020 is executed instead of S20.

[0065] In S3020 for planning the driving trajectory Td, the control block 120 executes the plan so as to define, in addition to the trajectory, time-series changes in at least one of the speed, acceleration, jerk, yaw angle, pitch angle, and roll angle, and time-series changes in the yaw rate, for each control period. As a result, as shown in Fig. 9, the driving trajectory Td of the third embodiment becomes an attitude control trajectory for avoiding a collision by coordinating the left and right distribution of braking force with the steering angle of the wheels 20 of the host vehicle 2. Therefore, further, as shown in Fig. 10, in the driving control subroutine of the third embodiment, S3300 is executed instead of S300.

[0066] In S3300 for setting the required range ΔF, the control block 120 sets the braking force required from the brake actuator 44 to be distributed to the front wheels 20fl, 20fr to avoid a collision according to the driving trajectory Td to a range that exceeds or is equal to or greater than a lower limit value for each wheel 20. At the same time, in S3300, the control block 120 sets the braking force required from the brake actuator 44 to be distributed to the rear wheels 20rl, 20rr to avoid a collision according to the driving trajectory Td to a range that exceeds or is equal to or greater than a lower limit value for each wheel 20. In the third embodiment, the required range ΔF set in this manner may be variably adjusted to a range of braking force that is coordinated with the steering angle that the steering actuator 42 is required to apply to at least one of the front wheels 20fl, 20fr and the rear wheels 20rl, 20rr to avoid a collision according to the driving trajectory Td.

[0067] 10, the actual braking force Fa is predicted in S310 following S3300. As a result, in the third embodiment, the actual braking force Fa is predicted and distributed between the front wheels 20fl, 20fr and between the rear wheels 20rl, 20rr in coordination with the actual steering angle applied by the steering actuator 42 to avoid a collision.

[0068] 10, in S320 following S310, a comparison determination between the actual braking force Fa and the required range ΔF is preferably performed for each of the front wheels 20fl, 20fr and the rear wheels 20rl, 20rr. Furthermore, in S330, to which the process proceeds upon a positive determination in S320 in the driving control subroutine, adjustments of the ground pressure, air pressure, and viscosity for increasing the resistance Fr, Frr are preferably performed for at least one wheel 20 of the front wheels 20fl, 20fr and the rear wheels 20rl, 20rr whose actual braking force Fa has fallen outside the required range ΔF.

[0069] According to the third embodiment described above, in the host vehicle 2 in an increased-risk scenario, in response to a prediction that the actual braking force Fa, which is distributed to the left and right wheels 20 in coordination with the steering angle applied by the steering actuator 42 to avoid a collision, will decrease outside the required range ΔF, the running resistance Fr is controlled to complement the predicted decrease in actual braking force Fa. As a result, even in the host vehicle 2 in which the actual braking force Fa, which is distributed to the left and right wheels in coordination with the steering angle to avoid a collision, is predicted to decrease outside the required range ΔF, the braking necessary to avoid a collision with the target 3 can be ensured by the combined effect of the actual braking force Fa and the running resistance Fr. Therefore, when the host vehicle 2 avoids a collision with the target 3, effective braking characteristics combined with steering angle coordination can be exerted, thereby making it possible to increase the reliability of driving assistance.

[0070] (Other embodiments) Although multiple embodiments have been described above, the present disclosure should not be construed as being limited to those embodiments, and can be applied to various embodiments and combinations within the scope that does not deviate from the gist of the present disclosure.

[0071] In a modified example, the dedicated computer constituting the driving assistance system 1 may have at least one of a digital circuit and an analog circuit as a processor. Here, the digital circuit is at least one of an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), an SOC (System on a Chip), a PGA (Programmable Gate Array), and a CPLD (Complex Programmable Logic Device). Furthermore, such a digital circuit may have a memory that stores a program.

[0072] In a modified example, S330 of the first and third embodiments and S2330 of the second embodiment may be executed in combination. In a modified example, the operator who manually drives the host vehicle 2 to which the driving assistance system 1 is applied may be a remote operator who remotely controls the driving of the host vehicle 2 from an external center. In a modified example, the driving assistance system 1 may be configured to be capable of realizing only automated driving tasks, without any manual driving assistance tasks that assist the operator in manual driving operations. [Explanation of symbols]

[0073] 1: Driving assistance system, 2: Host vehicle, 3: Target, 10: Memory, 12: Processor, 20: Wheel, 22: Vehicle body, 42: Steering actuator, 44: Braking actuator, Fa: Actual braking force, Fr: Running resistance, Fra: Air resistance, Frr: Road resistance, ΔF: Required range

Claims

1. A driving assistance system having a processor (12) for assisting a host vehicle (2) in avoiding a collision with a target (3), the system comprising: The processor: monitoring a collision risk of the host vehicle with the target; In a risk-rising scene in which the collision risk rises to a collision avoidance level that requires the host vehicle to avoid the collision, the actual braking force (Fa) that can be applied to the wheels (20) from the brake actuator (44) of the host vehicle is predicted to fall outside the required range (ΔF) for collision avoidance, and in response to this, the running resistance (Fr) applied to the host vehicle is controlled to complement the actual braking force.

2. Controlling the running resistance includes:

2. The driving assistance system according to claim 1, further comprising: applying to the host vehicle the running resistance that complements the actual braking force predicted to decrease outside the required range by controlling to increase road resistance (Frr) that the wheels of the host vehicle receive from the road surface on which the vehicle is traveling.

3. Controlling the running resistance includes: The driving assistance system according to claim 2 , further comprising: controlling the road resistance as the running resistance to increase by adjusting the air pressure in the wheels of the host vehicle to increase or decrease the air pressure.

4. Controlling the running resistance includes: The driving assistance system according to claim 2 , further comprising: controlling the road surface resistance as the running resistance to increase by adjusting the contact pressure between the wheels of the host vehicle and the road surface.

5. Controlling the running resistance includes: The driving assistance system according to claim 2 , further comprising: controlling the road surface resistance as the running resistance to increase by adjusting the viscosity of the contact surface between the wheels of the host vehicle and the road surface.

6. Controlling the running resistance includes:

2. The driving assistance system according to claim 1, further comprising: applying to the host vehicle the running resistance that complements the actual braking force predicted to decrease outside the required range by controlling to increase the air resistance (Fra) that the vehicle body (22) of the host vehicle receives from the outside air.

7. Controlling the running resistance includes: The driving assistance system according to claim 6 , further comprising: controlling the air resistance as the running resistance to increase by adjusting the opening of a window on the vehicle body of the host vehicle.

8. Controlling the running resistance includes:

2. The driving assistance system according to claim 1, further comprising: in the host vehicle in the increased risk scene, in response to a prediction of a decrease outside the required range of the actual braking force distributed to the left and right wheels in coordination with a steering angle applied from a steering actuator (42) to avoid the collision, controlling the running resistance so as to complement the predicted decrease in the actual braking force.

9. A driving assistance program stored in a storage medium (10) for assisting a host vehicle (2) in avoiding a collision with a target (3), the driving assistance program including instructions to be executed by a processor (12), the program comprising: monitoring a collision risk of the host vehicle with the target; and controlling the running resistance (Fr) applied to the host vehicle to complement the actual braking force in response to the actual braking force (Fa) that can be applied to the wheels (20) from a brake actuator (44) in the host vehicle in an increased risk scene, in which the collision risk increases to a collision avoidance level that requires the host vehicle to avoid the collision, being predicted to fall outside the required range (ΔF) for the collision avoidance.

10. A driving assistance method executed by a processor (12) for assisting a host vehicle (2) in avoiding a collision with a target (3), comprising: monitoring a collision risk of the host vehicle with the target; and controlling a running resistance (Fr) applied to the host vehicle to complement the actual braking force in response to a prediction that an actual braking force (Fa) that can be applied to a wheel (20) from a brake actuator (44) in the host vehicle in an increased risk scene, in which the collision risk has increased to a collision avoidance level that requires the host vehicle to avoid the collision, will fall outside a required range (ΔF) for the collision avoidance.

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