Driving support method and driving support device

Abstract

To suppress a rapid change in acceleration-deceleration and a delay in tracking to a target vehicular speed when switching the target vehicular speed.SOLUTION: A travel support method includes: generating a first target vehicular speed profile on the basis of a present travel environment and generating a second target vehicular speed profile on the basis of future travel environment (S2); generating first and second target acceleration-deceleration profiles in accordance with the first and second target vehicular speed profiles, respectively (S3); calculating an arrival time being a time to a clock time when a vehicular speed with the first and second target vehicular speed profiles will eventually be equal when a target vehicular speed to be used for speed control is switched from the first target vehicular speed profile to the second target vehicular speed profile (S5); and calculating target acceleration-deceleration, which changes from the first target acceleration-deceleration to the second target acceleration-deceleration as the arrival time decreases, so as to reach the second target acceleration-deceleration at a clock time later than the clock time when the arrival time has elapsed, by weighting the first and second target acceleration-deceleration depending on the arrival time (S6, S7).SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a driving assistance method and a driving assistance device. [Background technology]

[0002] The following Patent Document 1 describes a vehicle control device that compares a first recommended vehicle speed in a first section currently being traveled with a second recommended speed in a second section to be traveled next, and if the second recommended speed is lower than the first recommended speed, controls the speed after reaching the second section so that it approaches the second recommended speed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 021734 Brochure Summary of the Invention [Problem to be solved by the invention]

[0004] When the target vehicle speed is switched as in Patent Document 1, the target acceleration / deceleration may suddenly change at the time of switching, which may cause the vehicle behavior to become unstable. If the rate of change of the target acceleration / deceleration is limited to prevent this sudden change in the target acceleration / deceleration, there is a risk of a delay in following up to the target vehicle speed. The present invention has been made in view of the above problems of the prior art, and aims to suppress a sudden change in target acceleration / deceleration and a delay in following up to the target vehicle speed when the target vehicle speed is switched. [Means for solving the problem]

[0005] In one aspect of the driving assistance method of the present invention, the driving environment in which the host vehicle is traveling is detected, and based on the detected driving environment, a first target vehicle speed profile based on the current driving environment is generated, and a second target vehicle speed profile based on the future driving environment is generated. A first target acceleration / deceleration corresponding to the first target vehicle speed profile and a second target acceleration / deceleration corresponding to the second target vehicle speed profile are generated. When the target vehicle speed profile used for vehicle speed control of the host vehicle is switched from the first target vehicle speed profile to the second target vehicle speed profile, an arrival time is calculated, which is the time from the current time to the future time at which the vehicle speed of the first target vehicle speed profile and the vehicle speed of the second target vehicle speed profile will be equal. By weighting the first target acceleration / deceleration and the second target acceleration / deceleration according to the arrival time, the target acceleration / deceleration, which changes from the first target acceleration / deceleration to the second target acceleration / deceleration as the arrival time decreases, is calculated so that the second target acceleration / deceleration is reached at a time later than the time at which the arrival time has elapsed, and the acceleration / deceleration of the host vehicle is controlled based on the target acceleration / deceleration. [Effects of the Invention]

[0006] According to the present invention, it is possible to suppress a sudden change in acceleration / deceleration and a delay in following up to the target vehicle speed when the target vehicle speed is switched. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram illustrating an example of a schematic configuration of a vehicle equipped with a driving assistance device according to an embodiment. [Figure 2] 1A is an explanatory diagram of switching of a target vehicle speed profile, FIG. 1B is an explanatory diagram of interpolation of a target acceleration / deceleration, and FIG. 1C is a diagram showing an example of an interpolation gain. [Figure 3] 2 is a block diagram illustrating an example of a functional configuration of a controller in FIG. 1. FIG. [Figure 4] FIG. 2 is a block diagram illustrating an example of a functional configuration of an acceleration / deceleration command arbitration unit. [Figure 5] FIG. 4 is a block diagram illustrating an example of a functional configuration of a target acceleration / deceleration generating unit. [Figure 6] 3 is a flowchart illustrating an example of a driving assistance method according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, identical or similar parts are designated by identical or similar reference numerals, and redundant explanations will be omitted. Each drawing is a schematic view, and may differ from the actual product. The embodiments shown below exemplify devices and methods for embodying the technical concept of the present invention, and the technical concept of the present invention is not limited to the devices and methods exemplified in the following embodiments. The technical concept of the present invention can be modified in various ways within the technical scope described in the claims.

[0009] (composition) The host vehicle 1 is equipped with a driving assistance device 10 that assists in driving the host vehicle 1. The driving assistance device 10 detects the driving environment around the host vehicle 1 and automatically controls the driving of the host vehicle 1 based on the detected driving environment, thereby assisting the driving of the host vehicle 1. For example, the driving assistance of the vehicle 1 by the driving assistance device 10 may include autonomous driving control in which the vehicle 1 is automatically driven without the involvement of an occupant (e.g., a driver). Also, for example, the driving assistance of the vehicle 1 by the driving assistance device 10 may include automatic control of at least one of the driving force and braking force of the vehicle 1.

[0010] The driving assistance device 10 includes a positioning device 11, a map database 12, a navigation device 13, an external sensor 14, a vehicle sensor 15, a controller 16, and an actuator 17. In the drawings, the map database is referred to as a "map DB." The positioning device 11 measures the current position of the vehicle 1. The positioning device 11 may include, for example, a Global Positioning System (GNSS) receiver. The GNSS receiver is, for example, a Global Positioning System (GPS) receiver, and receives radio waves from multiple navigation satellites to measure the current position of the vehicle 1.

[0011] The map database 12 may store high-precision map data (hereinafter simply referred to as "high-precision map") suitable as map information for autonomous driving. The high-precision map is map data with higher precision than map data for navigation (hereinafter simply referred to as "navigation map"). The road information contained in the high-precision map includes more detailed information on a lane-by-lane basis than road-by-road basis information. Hereinafter, the lane-by-lane information contained in the high-precision map data may be referred to as "lane information."

[0012] For example, a high-precision map includes, as lane information, information on lane nodes that indicate reference points on lane reference lines (e.g., the center line within a lane) and information on lane links that indicate the section configuration of the lane between the lane nodes. The high-precision map further includes information about features such as the type and location coordinates of features that exist on or near the lane, such as stop lines, signs, buildings, utility poles, curbs, crosswalks, and structures, as well as information about the features, such as the identification numbers of lane nodes and lane link identification numbers that correspond to the location coordinates of the features.

[0013] The navigation device 13 recognizes the current position of the vehicle 1 using the positioning device 11, and acquires map information for the current position from the map database 12. The navigation device 13 sets a driving route to the destination input by the occupant, and provides route guidance to the occupant along this driving route. Furthermore, the navigation device 13 outputs information about the set driving route to the controller 16. When performing autonomous driving control, the controller 16 automatically drives the vehicle 1 so that the vehicle 1 travels along the driving route set by the navigation device 13.

[0014] The external sensor 14 detects various information (driving environment information) about the driving environment around the vehicle 1, for example, objects around the vehicle 1. The external sensor 14 detects the environment around the vehicle 1, such as objects present around the vehicle 1, the relative positions between the vehicle 1 and the objects, the distance between the vehicle 1 and the objects, and the direction in which the objects exist. The external sensor 14 outputs the detected information about the driving environment to the controller 16 as driving environment information. For example, the external sensor 14 detects the relative positions of other vehicles and targets around the vehicle 1 relative to the vehicle 1. Here, targets include, for example, traffic lights installed on the road on which the vehicle 1 is traveling, lines on the road surface (lane markings, etc.), curbs on the shoulders of the road, guardrails, etc.

[0015] The external sensor 14 may include a monocular camera such as a full HD color camera. The camera captures an image including a recognition target in the environment surrounding the vehicle 1, and outputs the captured image to the controller 16 as driving environment information. The external sensor 14 may also include a distance measuring device such as a laser range finder (LRF), radar, or a laser radar such as LiDAR (Light Detection and Ranging). The distance measuring device detects the relative position of the vehicle, which is determined by the relative distance and direction to an object present around the vehicle. The distance measuring device outputs the detected distance data to the controller 16 as driving environment information.

[0016] The vehicle sensor 15 detects various information (vehicle information) obtained from the host vehicle 1. The vehicle sensor 15 includes, for example, a vehicle speed sensor that detects the traveling speed (vehicle speed) V of the host vehicle 1, a wheel speed sensor that detects the rotational speed of each tire equipped on the host vehicle 1, a three-axis acceleration sensor (G sensor) that detects the acceleration (including deceleration) of the host vehicle 1 in three axial directions, a steering angle sensor that detects the steering angle (including the turning angle) θs, a gyro sensor that detects the angular velocity generated in the host vehicle 1, a yaw rate sensor that detects the yaw rate γ, an accelerator sensor that detects the operation amount α of the accelerator pedal of the host vehicle 1, and a brake sensor that detects the brake operation amount by the driver.

[0017] The controller 16 is an electronic control unit (ECU) that performs driving assistance control of the host vehicle 1. When performing driving assistance control of the host vehicle 1, the controller 16 automatically controls the driving of the host vehicle 1 based on the surrounding driving environment. The controller 16 includes a processor 20 and peripheral components such as a storage device 21. The processor 20 may be, for example, a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit). The storage device 21 may include a semiconductor storage device, a magnetic storage device, an optical storage device, etc. The storage device 21 may include memories such as a register, a cache memory, a ROM (Read Only Memory) used as a main memory device, and a RAM (Random Access Memory). The functions of the controller 16 described below are realized by, for example, the processor 20 executing a computer program stored in the storage device 21 .

[0018] The controller 16 may be formed by dedicated hardware for executing each of the information processes described below. For example, the controller 16 may include a functional logic circuit configured in a general-purpose semiconductor integrated circuit, such as a programmable logic device (PLD) such as a field-programmable gate array (FPGA).

[0019] The actuator 17 operates the accelerator opening and braking device of the host vehicle 1 in response to a control signal from the controller 16 to generate a driving force for driving the host vehicle 1 or a braking force for braking the host vehicle 1. The actuator 17 includes an accelerator opening actuator and a brake control actuator. The accelerator opening actuator controls the accelerator opening of the host vehicle 1. The brake control actuator controls the braking operation of the braking device of the host vehicle 1. The actuator 17 may also include a steering actuator that controls the steering direction and steering amount of the steering mechanism of the host vehicle 1. The actuator 17 may operate the steering mechanism of the host vehicle 1 in response to a control signal from the controller 16.

[0020] Next, the acceleration / deceleration control of the controller 16 during driving support control of the host vehicle 1 will be described. The controller 16 acquires information about the driving environment around the vehicle 1 based on the driving environment information output by the external sensor 14. In addition, the controller 16 measures the current position of the vehicle 1 using the positioning device 11 and acquires information about the driving environment around the vehicle 1 from the map database 12. The controller 16 generates a plurality of target vehicle speed profiles Vr1(t), Vr2(t), ... based on the traveling environment of the host vehicle 1. Furthermore, the controller 16 time-differentiates each of the target vehicle speed profiles Vr1(t), Vr2(t), ... to generate target acceleration / deceleration Ar1(t), Ar2(t), ....

[0021] For example, the controller 16 generates a first target vehicle speed profile Vr1(t) indicated by a dashed line and a second target vehicle speed profile Vr2(t) indicated by a two-dot chain line in Fig. 2(a). The controller 16 also time-differentiates the first and second target vehicle speed profiles Vr1(t) and Vr2(t) to generate a first target acceleration / deceleration Ar1(t) indicated by a dashed line and a second target acceleration / deceleration Ar2(t) indicated by a two-dot chain line in Fig. 2(b). 2(a) is a target vehicle speed profile in which the vehicle speed is constant. For example, the controller 16 generates the first target vehicle speed profile Vr1(t) based on the speed limit (current driving environment) of the road at the point where the host vehicle 1 is currently traveling, which is acquired from the map database 12.

[0022] 2(a) is a target vehicle speed profile in which the vehicle speed decreases. For example, the controller 16 generates the second target vehicle speed profile Vr2(t) based on the position information of the stop line ahead of the host vehicle 1 acquired from the map database 12, the speed limit of the road ahead of the point where the host vehicle 1 is currently traveling, or the position of an object ahead of the host vehicle 1 detected by the external sensor 14 (future traveling environment). Although only the first and second target vehicle speed profiles Vr1(t) and Vr2(t) are illustrated in this specification, the number of target vehicle speed profiles generated by the controller 16 is not limited to two. The controller 16 may generate three or more target vehicle speed profiles according to various criteria based on the driving environment. The driving environment (current driving environment and future driving environment) is not limited to the speed limit of the road, the position information of the stop line, and the position of objects ahead, as described above, but environmental factors that cause speed changes, such as road width and traffic congestion information, can be appropriately adopted.

[0023] The controller 16 arbitrates between these multiple target vehicle speed profiles and sets the slowest vehicle speed among the vehicle speeds in these target vehicle speed profiles as the target vehicle speed. In the example of FIG. 2(a), since the first target vehicle speed profile Vr1(t) is lower than the second target vehicle speed profile Vr2(t) at the current time tn, the vehicle speed of the first target vehicle speed profile Vr1(t) is selected as the target vehicle speed.

[0024] Then, at a future time t0, the first target vehicle speed profile Vr1(t) and the second target vehicle speed profile Vr2(t) become equal, and thereafter the second target vehicle speed profile Vr2(t) becomes lower than the first target vehicle speed profile Vr1(t). Therefore, the vehicle speed of the second target vehicle speed profile Vr2(t) is selected as the target vehicle speed. In other words, the target vehicle speed profile used for vehicle speed control of the host vehicle 1 switches from the first target vehicle speed profile Vr1(t) to the second target vehicle speed profile Vr2(t) at time t0. Hereinafter, when the target vehicle speed profile used for vehicle speed control of the host vehicle 1 is switched from the first target vehicle speed profile to the second target vehicle speed profile, the time t0 at which the first target vehicle speed profile Vr1(t) and the second target vehicle speed profile Vr2(t) become equal may be referred to as the "switching time."

[0025] Here, as shown by the thin solid line, if the lower of the vehicle speeds of the first target vehicle speed profile Vr1(t) and the second target vehicle speed profile Vr2(t) is simply selected and set as the target vehicle speed, the target acceleration / deceleration may change suddenly at the switching time t0. Therefore, if the driving force or braking force of the host vehicle 1 is controlled based on the suddenly changing target acceleration / deceleration, there is a risk that the vehicle behavior may become unstable. If the rate of change of the target acceleration / deceleration is limited to prevent this sudden change in the target acceleration / deceleration, there is a risk that a delay in following up to the target vehicle speed may occur.

[0026] Therefore, the controller 16 calculates the target acceleration / deceleration by interpolating between the first target acceleration / deceleration and the second target acceleration / deceleration during the period from time tp, which is before the switching time t0 at which the vehicle speed of the first target vehicle speed profile and the vehicle speed of the second target vehicle speed profile will become equal in the future, to time tf, which is after the switching time t0. The thick solid line in Fig. 2(b) indicates the feedforward target acceleration / deceleration Aff calculated by interpolating the first target acceleration / deceleration and the second target acceleration / deceleration. The thick solid line in Fig. 2(a) indicates the target vehicle speed profile when the target vehicle speed for the period from time tp to time tf is generated based on the feedforward target acceleration / deceleration Aff. Hereinafter, the feedforward target acceleration / deceleration will be referred to as the "FF target acceleration / deceleration."

[0027] In order to interpolate between the first target acceleration / deceleration and the second target acceleration / deceleration, the controller 16 calculates the arrival time tc, which is the time from the current time tn to the switching time t0. The controller 16 weights the first target acceleration / deceleration and the second target acceleration / deceleration according to the arrival time tc, and calculates the weighted sum that changes from the first target acceleration / deceleration to the second target acceleration / deceleration during the period from time tp to time tf as the arrival time tc decreases, as the FF target acceleration / deceleration Aff.

[0028] In this way, by controlling the acceleration / deceleration of the host vehicle 1 based on the feedforward target acceleration / deceleration Aff obtained by interpolating the first target acceleration / deceleration and the second target acceleration / deceleration during the period from time tp before the switching time t0 to time tf after the switching time t0, a sudden change in the target acceleration / deceleration when the target vehicle speed profile is switched can be suppressed. Furthermore, by starting the control of acceleration / deceleration for switching the target vehicle speed profile from time tp, which is before the switching time t0, it is possible to suppress a delay in following up to the target vehicle speed profile after switching.

[0029] Note that Figure 2(a) shows an example in which the target vehicle speed profiles Vr1(t), Vr2(t), ... are generated as time-vehicle speed profiles indicating the target vehicle speed at each time, but the FF target acceleration / deceleration Aff can also be generated in the same way by generating them as distance-vehicle speed profiles that define the relationship between the travel distance of the host vehicle 1 and the target vehicle speed.

[0030] The acceleration / deceleration control of the host vehicle 1 by the controller 16 will be described in more detail below with reference to Fig. 3. The controller 16 functions as a target vehicle speed generating unit 30, a vehicle speed command arbitration unit 31, an acceleration / deceleration command arbitration unit 32, a target acceleration / deceleration generating unit 33, and a vehicle control unit 34. The target vehicle speed generating unit 30 generates a plurality of target vehicle speed profiles Vr1(t), Vr2(t), ... based on the driving environment around the vehicle 1 detected by the external sensor 14 and the driving environment obtained from the map database 12 based on the current position of the vehicle 1 measured by the positioning device 11. The target vehicle speed generating unit 30 also generates target acceleration / deceleration Ar1(t), Ar2(t), ... by time-differentiating each of the target vehicle speed profiles Vr1(t), Vr2(t), ...

[0031] The vehicle speed command arbitration unit 31 arbitrates among the generated multiple target vehicle speed profiles Vr1(t), Vr2(t), ..., and sets the slowest vehicle speed among the vehicle speeds at the current time of these target vehicle speed profiles Vr1(t), Vr2(t), ... as the target vehicle speed Vr. Hereinafter, a case will be described in which the vehicle speed command arbitration unit 31 switches the target vehicle speed profile currently used for vehicle speed control of the host vehicle 1 from the first target vehicle speed profile Vr1(t) to the second target vehicle speed profile Vr2(t).

[0032] The acceleration / deceleration command arbitration unit 32 determines, based on the target vehicle speed profiles Vr1(t), Vr2(t), . . . , whether or not a switch in the target vehicle speed profile will occur in the future. If a switch from the first target vehicle speed profile Vr1(t) to the second target vehicle speed profile Vr2(t) occurs in the future, the acceleration / deceleration command arbitration unit 32 outputs a target acceleration / deceleration that interpolates between the first target acceleration / deceleration and the second target acceleration / deceleration before and after the switch as the FF target acceleration / deceleration Aff.

[0033] 4 is a block diagram showing an example of the functional configuration of the acceleration / deceleration command arbitration unit 32. The acceleration / deceleration command arbitration unit 32 includes a reaching time calculation unit 40, an interpolation gain calculation unit 41, and a target acceleration / deceleration interpolation unit . The arrival time calculation unit 40 calculates the arrival time tc from the current time tn to the switching time t0 at which the vehicle speed of the first target vehicle speed profile and the vehicle speed of the second target vehicle speed profile will become equal in the future.

[0034] The arrival time calculation unit 40 calculates the arrival time tc based on the first and second target vehicle speed profiles Vr1(tn), Vr2(tn) at the current time and the first and second target acceleration / deceleration Ar1, Ar2 at the current time. For example, when the first target vehicle speed profile Vr1(t) and the second target vehicle speed profile Vr2(t) are linear functions of the variable t or constants, the arrival time tc can be calculated based on the following equation (1). tc=(Vr1(tn)-Vr2(tn)) / (Ar2-Ar1) …(1)

[0035] Even when the first target vehicle speed profile Vr1(t) and the second target vehicle speed profile Vr2(t) are nonlinear functions (for example, quadratic functions of the variable t), the arrival time tc can be calculated based on the first and second target vehicle speed profiles Vr1(tn), Vr2(tn) at the current time and the first and second target acceleration / deceleration Ar1, Ar2 at the current time. The arrival time calculation unit 40 may obtain the arrival time tc based on the elapsed time t and a map of the first target vehicle speed profile Vr1(t) and the second target vehicle speed profile Vr2(t).

[0036] The interpolation gain calculation unit 41 calculates an interpolation gain K, which is a weighting coefficient according to the arrival time tc. For example, the interpolation gain calculation section 41 may set a map of the characteristics shown in FIG. 2(c) and obtain the interpolation gain K from this map. When the value of the arrival time tc is greater than the time difference t0-tp between the switching time t0 and a predetermined time tp before the switching time t0 (i.e., when the current time tn is a time before the time tp), the value of the interpolation gain K is 0.

[0037] When the value of the arrival time tc is smaller than the time difference t0-tf (<0) between the switching time t0 and a predetermined time tf that is later than the switching time t0 (i.e., when the current time tn is later than the time tf), the value of the interpolation gain K is 1. When the value of the arrival time tc changes from t0-tp to t0-tf (that is, when the current time tn changes from time tp to time tf), the value of the interpolation gain K changes from 0 to 1.

[0038] See Fig. 4. The target acceleration / deceleration interpolation unit 42 weights the first target acceleration / deceleration Ar1 and the second target acceleration / deceleration Ar2 at the current time based on the interpolation gain K, and outputs the weighted sum as the FF target acceleration / deceleration Aff. Specifically, the FF target acceleration / deceleration Aff is calculated based on the following equation (2). Aff = (1 - K) × Ar1 + K × Ar2 … (2) An example of the FF target acceleration / deceleration Aff is shown by the thick solid line in Figure 2(b). By calculating the FF target acceleration / deceleration Aff based on the above formula (2), the FF target acceleration / deceleration Aff gradually changes from the first target acceleration / deceleration Ar1 to the second target acceleration / deceleration Ar2 over the period from the predetermined time tp to the time tf.

[0039] Here, for example, the interpolation gain calculation section 41 may set the characteristics of the interpolation gain K so that the time difference t0-tp between the predetermined time tp and the switching time t0 becomes Tprev in the following equation (3). Tprev = (Ar2 - Ar1) / J … (3) In equation (3), J is a constant set according to the maximum allowable jerk, and Ar1 and Ar2 are the first target acceleration / deceleration and the second target acceleration / deceleration at the switching time t0. Furthermore, the interpolation gain calculation unit 41 appropriately sets the predetermined time tf so that the switching time t0 also comes later. By setting the predetermined times tp and tf in this manner, the change over time of the FF target acceleration / deceleration Aff from the predetermined time tp to the time tf can be made smaller than the constant J corresponding to the maximum allowable jerk, thereby suppressing abrupt changes in vehicle behavior.

[0040] Furthermore, since the FF target acceleration / deceleration Aff starts to change from the first target acceleration / deceleration to the second target acceleration / deceleration from time tp before the switching time t0, the time difference between the switching time t0 and the predetermined time tf can be set short even if the FF target acceleration / deceleration Aff changes slowly. This allows the target speed to follow the second target vehicle speed profile Vr2(t) relatively quickly. See Fig. 3. The target acceleration / deceleration generation unit 33 calculates a feedback target acceleration / deceleration Afb based on the deviation between the target vehicle speed Vr selected by the vehicle speed command arbitration unit 31 and the current vehicle speed V of the host vehicle. Hereinafter, the feedback target acceleration / deceleration may be referred to as "FB target acceleration / deceleration." The target acceleration / deceleration generation unit 33 calculates an acceleration / deceleration command value Ar based on the FF target acceleration / deceleration Aff and the FB target acceleration / deceleration Afb.

[0041] For example, the target acceleration / deceleration generating unit 33 may calculate the acceleration / deceleration command value Ar based on the following equation (4). Ar=Aff+Afb =(1-K)×Ar1+K×Ar2-Kfb×(Vr-V) …(4) 5 is a block diagram showing an example of the functional configuration of the target acceleration / deceleration generating unit 33. The target acceleration / deceleration generating unit 33 includes a subtractor 50, a gain multiplier 51, and an adder 52.

[0042] A subtractor 50 calculates the deviation (Vr-V) between the target vehicle speed Vr selected by the vehicle speed command arbitration unit 31 and the current vehicle speed V of the host vehicle. A gain multiplication unit 51 calculates the product Kfb×(Vr-V) of a predetermined gain (-Kfb) and the deviation (Vr-V) as an FB target acceleration / deceleration Afb. An adder 52 calculates the sum of the FF target acceleration / deceleration Aff and the FB target acceleration / deceleration Afb as an acceleration / deceleration command value Ar. See Fig. 3. The vehicle control unit 34 generates a driving force or a braking force on the wheels of the host vehicle 1 by controlling the accelerator opening actuator or the brake control actuator of the actuator 17 based on the acceleration / deceleration command value Ar.

[0043] (operation) Next, an example of a driving support method according to an embodiment will be described with reference to FIG. In step S1, the external sensor 14 detects the driving environment around the host vehicle 1. The controller 16 also acquires information about the driving environment around the host vehicle 1 from the map database 12. In step S2, the target vehicle speed generating unit 30 generates a plurality of target vehicle speed profiles Vr1(t), Vr2(t), . . . based on the traveling environment.

[0044] In step S3, the target vehicle speed generating unit 30 generates target acceleration / deceleration Ar1(t), Ar2(t), . . . by differentiating each of the target vehicle speed profiles Vr1(t), Vr2(t), . In step S4, the acceleration / deceleration command arbitration unit 32 determines whether or not a change in the target vehicle speed profile will occur. If a change in the target vehicle speed profile will occur (step S4: Y), the process proceeds to step S5. If a change in the target vehicle speed profile will not occur (step S4: N), the process proceeds to step S8. Hereinafter, the target vehicle speed profile before switching will be referred to as a first target vehicle speed profile Vr1(t), and the target vehicle speed profile after switching will be referred to as a second target vehicle speed profile Vr2(t).

[0045] In step S5, the arrival time calculation unit 40 calculates the arrival time tc from the current time tn to the switching time t0 at which the vehicle speed of the first target vehicle speed profile and the vehicle speed of the second target vehicle speed profile will become equal in the future. In step S6, the interpolation gain calculation unit 41 calculates the interpolation gain K according to the arrival time tc. In step S7, the target acceleration / deceleration interpolation unit 42 calculates the FF target acceleration / deceleration Aff as a weighted sum of the first target acceleration / deceleration Ar1 and the second target acceleration / deceleration Ar2 at the current time, weighted based on the interpolation gain K. Thereafter, the process proceeds to step S9.

[0046] In step S8, the acceleration / deceleration command arbitration unit 32 sets the current target acceleration / deceleration to the FF target acceleration / deceleration Aff, after which the process proceeds to step S9. In step S9, the target acceleration / deceleration generating unit 33 calculates the acceleration / deceleration command value Ar based on the deviation between the current target vehicle speed Vr and the current vehicle speed V of the host vehicle, and the FF target acceleration / deceleration Aff. In step S10, the vehicle control unit 34 controls the actuator 17 based on the acceleration / deceleration command value Ar to generate a driving force or a braking force on the wheels of the host vehicle 1. Then, the process ends.

[0047] (Effects of the embodiment) (1) The external sensor 14 detects the driving environment in which the host vehicle 1 is traveling. The controller 16 generates a first target vehicle speed profile based on the current driving environment and a second target vehicle speed profile based on the future driving environment based on the detected driving environment, generates a first target acceleration / deceleration according to the first target vehicle speed profile and a second target acceleration / deceleration according to the second target vehicle speed profile, and when switching the target vehicle speed profile used for vehicle speed control of the host vehicle 1 from the first target vehicle speed profile to the second target vehicle speed profile, calculates an arrival time which is the time from the current time to a future time at which the vehicle speed of the first target vehicle speed profile and the vehicle speed of the second target vehicle speed profile will be equal, and weights the first target acceleration / deceleration and the second target acceleration / deceleration according to the arrival time, thereby calculating the target acceleration / deceleration which changes from the first target acceleration / deceleration to the second target acceleration / deceleration as the arrival time decreases so as to reach the second target acceleration / deceleration at a time later than the time at which the arrival time has elapsed, and controls the acceleration / deceleration of the host vehicle 1 based on the target acceleration / deceleration.

[0048] This allows the target acceleration / deceleration when the target vehicle speed profile is switched to be calculated by interpolating the first target acceleration / deceleration and the second target acceleration / deceleration before and after the switch. This makes it possible to suppress a sudden change in the target acceleration / deceleration. Furthermore, by starting the control of the acceleration / deceleration accompanying the switch of the target vehicle speed profile before the switch of the target vehicle speed profile, it is possible to suppress a delay in following the target vehicle speed profile after the switch.

[0049] (2) The controller 16 may set the arrival time at which the weight of the first target acceleration / deceleration decreases and the weight of the second target acceleration / deceleration begins to increase in the above weighting, based on the result of dividing the difference between the first target acceleration / deceleration and the second target acceleration / deceleration at the time when the arrival time has elapsed by a constant corresponding to the maximum allowable jerk. This limits the jerk that occurs when switching from the first target vehicle speed profile to the second target vehicle speed profile to a maximum allowable jerk or less, thereby making it possible to suppress abrupt vehicle behavior of the host vehicle 1.

[0050] (3) The controller 16 may calculate the arrival time based on the vehicle speed at the current time on the first target vehicle speed profile, the vehicle speed at the current time on the second target vehicle speed profile, the first target acceleration / deceleration at the current time, and the second target acceleration / deceleration at the current time. This makes it possible to easily interpolate between the first target acceleration / deceleration and the second target acceleration / deceleration.

[0051] (4) The controller 16 may obtain a weighting coefficient for weighting the first target acceleration / deceleration and the second target acceleration / deceleration from a map that defines the relationship between the arrival time and the weighting coefficient. This makes it easy to set weighting coefficients according to the arrival times. (5) The controller 16 may calculate an acceleration / deceleration command value based on the deviation between the smaller of the target vehicle speeds at the current time of the first target vehicle speed profile and the second target vehicle speed profile and the vehicle speed of the host vehicle 1, and the target acceleration / deceleration, and control the acceleration / deceleration of the host vehicle 1 based on the acceleration / deceleration command value. This allows the acceleration / deceleration of the host vehicle 1 to approach the acceleration / deceleration command value, and the acceleration / deceleration of the host vehicle 1 to be controlled so that the vehicle speed of the host vehicle 1 approaches the target vehicle speed. [Explanation of symbols]

[0052] 1...Own vehicle, 10...Driving assistance device, 11...Positioning device, 12...Map database, 13...Navigation device, 14...External sensor, 15...Vehicle sensor, 16...Controller, 17...Actuator, 20...Processor, 21...Storage device, 30...Target vehicle speed generation unit, 31...Vehicle speed command arbitration unit, 32...Acceleration / deceleration command arbitration unit, 33...Target acceleration / deceleration generation unit, 34...Vehicle control unit, 40...Arrival time calculation unit, 41...Interpolation gain calculation unit, 42...Target acceleration / deceleration interpolation unit, 50...Subtractor, 51...Gain multiplication unit, 52...Adder

Claims

1. Detect the driving environment in which the vehicle is traveling, generating a first target vehicle speed profile based on the current driving environment and a second target vehicle speed profile based on the future driving environment based on the detected driving environment; generating a first target acceleration / deceleration according to the first target vehicle speed profile and a second target acceleration / deceleration according to the second target vehicle speed profile; when switching the target vehicle speed profile used for vehicle speed control of the host vehicle from the first target vehicle speed profile to the second target vehicle speed profile, calculating an arrival time that is a time from a current time to a future time at which the vehicle speed of the first target vehicle speed profile and the vehicle speed of the second target vehicle speed profile will be equal, weighting the first target acceleration / deceleration and the second target acceleration / deceleration in accordance with the arrival time, thereby calculating a target acceleration / deceleration that changes from the first target acceleration / deceleration to the second target acceleration / deceleration as the arrival time decreases so that the target acceleration / deceleration reaches the second target acceleration / deceleration at a time later than a time at which the arrival time has elapsed; A driving assistance method comprising controlling an acceleration / deceleration of the host vehicle based on the target acceleration / deceleration.

2. 2. The driving assistance method according to claim 1, further comprising: setting a time when, in the weighting, the weight of the first target acceleration / deceleration starts to decrease and the weight of the second target acceleration / deceleration starts to increase, based on a result of dividing a difference between the first target acceleration / deceleration and the second target acceleration / deceleration at the time when the arrival time has elapsed by a constant corresponding to a maximum allowable jerk, and based on a time in the future when the vehicle speed of the first target vehicle speed profile and the vehicle speed of the second target vehicle speed profile will be equal.

3. 3. The driving assistance method according to claim 1, wherein the arrival time is calculated based on a vehicle speed at a current time on the first target vehicle speed profile, a vehicle speed at a current time on the second target vehicle speed profile, a first target acceleration / deceleration at a current time, and a second target acceleration / deceleration at a current time.

4. 4. The driving assistance method according to claim 1, wherein a weighting coefficient for weighting the first target acceleration / deceleration and the second target acceleration / deceleration is obtained from a map that defines a relationship between the arrival time and the weighting coefficient.

5. calculating an acceleration / deceleration command value based on a deviation between a smaller one of the target vehicle speeds at the current time of the first target vehicle speed profile and the second target vehicle speed profile and the vehicle speed of the host vehicle, and the target acceleration / deceleration; 5. The driving support method according to claim 1, further comprising controlling the acceleration / deceleration of the host vehicle based on the acceleration / deceleration command value.

6. a sensor for detecting the driving environment in which the host vehicle is driving; a controller that generates a first target vehicle speed profile based on the current driving environment and generates a second target vehicle speed profile based on a future driving environment based on the detected driving environment, generates a first target acceleration / deceleration according to the first target vehicle speed profile and a second target acceleration / deceleration according to the second target vehicle speed profile, and, when switching the target vehicle speed profile used for vehicle speed control of the host vehicle from the first target vehicle speed profile to the second target vehicle speed profile, calculates an arrival time that is the time from the current time to a future time when the vehicle speed of the first target vehicle speed profile and the vehicle speed of the second target vehicle speed profile will be equal, and weights the first target acceleration / deceleration and the second target acceleration / deceleration according to the arrival time, thereby calculating a target acceleration / deceleration that changes from the first target acceleration / deceleration to the second target acceleration / deceleration as the arrival time decreases so as to reach the second target acceleration / deceleration at a time later than a time when the arrival time has elapsed, and controls the acceleration / deceleration of the host vehicle based on the target acceleration / deceleration; A driving assistance device comprising:

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