JP2019059429A - Vehicle driving support apparatus - Google Patents

Abstract

To reduce the possibility of making a determination that a steering follow-up target vehicle is in a state of departing from a travel lane, later than the start time point of actual travel lane departure.SOLUTION: When at least any one of a first departure completion determination condition to a third departure completion determination condition is established, a driving support ECU (10) determines that a steering follow-up target vehicle is in a departure completion state. When at least any one of a first departure start determination condition to a third departure start determination condition is established, the driving support ECU (10) determines that the steering follow-up target vehicle is in a departure start state. When the steering follow-up target vehicle is in the departure completion state, the driving support ECU (10) stops steering follow-up control. When the steering follow-up target vehicle is in the departure start state, the driving support ECU (10) lowers an upper limit guard value and executes the steering follow-up control.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vehicle driving support device that performs steering control for causing a host vehicle to travel along a target travel line based on the travel locus of another vehicle (front vehicle) traveling in the front region of the host vehicle.

  One of the conventionally known vehicle driving support devices (hereinafter referred to as "conventional devices") generates a traveling trace of a steering following target vehicle selected from among preceding vehicles traveling in front of the own vehicle. . The conventional device performs steering control (steering follow control) so that the host vehicle travels along a target travel line based on the generated travel locus.

  When steering following control is performed, if the target vehicle following the steering deviates from the traveling lane (the traveling lane), there is a high possibility that the traveling locus is largely deviated from the vicinity of the center of the traveling line. Therefore, in this case, it is not preferable for the conventional device to set the target travel line using the generated travel locus. For this reason, the conventional device determines whether or not the steering following target vehicle deviates from the traveling lane as follows, and when the steering following target vehicle deviates from the traveling lane: Stop steering following control.

  In the conventional device, a steering following target vehicle at the time when the steering following target vehicle exists at a position on the traveling locus corresponding to the current position of the own vehicle (hereinafter referred to as "own vehicle corresponding position"). The positional relationship between and and the white line is acquired using the traveling trace of the target vehicle following the steering.

  That is, in the conventional device, first, the positional relationship between the steering target vehicle in the past when it was present at the position corresponding to the vehicle (hereinafter simply referred to as "the target vehicle for tracking the past steering") and the white line. A first distance DL1 in the lane width direction between the vehicle corresponding position and the white line, and a first yaw angle θ1 with respect to the white line of the target vehicle following the steering in the past are acquired. Note that the first yaw angle θ1 is calculated by subtracting the yaw angle θ4 with respect to the white line of the host vehicle from the yaw angle θ3 with respect to the traveling locus of the steering follow-up target vehicle of the host vehicle.

Next, according to the following formula, the conventional apparatus estimates the arrival time Tx1 until the target vehicle following the steering reaches the white line and the movement required for the target vehicle following the steering to move from the position corresponding to the vehicle to the current position The time Tx2 is calculated.
Expected arrival time Tx1 = “first distance DL1 / estimated lateral speed (steering follow target vehicle speed v × sin θ1)”
Travel time Tx2 = “inter-vehicle distance / steering follow target vehicle speed v”

  Further, the conventional apparatus calculates the determination time Tx (= the arrival expected time Tx1−the movement time Tx2) by subtracting the moving time Tx2 from the determination time Tx = the expected arrival time Tx1. When the determination time Tx is smaller than the predetermined threshold value, the conventional device determines that the steering follow-up target vehicle is in a situation of departing from the traveling lane, and stops the steering follow-up control (see, for example, Patent Document 1).

JP, 2016-101783, A

  The conventional apparatus is premised on the fact that the yaw angle to the white line of the steering following target vehicle is constant and does not change from the first yaw angle θ1 while the steering following target vehicle moves from the vehicle corresponding position to the current position. And the lane departure of the target vehicle following the steering is determined.

  However, in practice, it is possible that the yaw angle with respect to the white line of the steering following target vehicle may be changed from the first yaw angle θ1 while the steering following target vehicle is moving from the vehicle corresponding position to the current position. . In this case, since the accuracy of the determination time Tx is lowered due to the decrease in the accuracy of the estimated arrival time Tx1, the accuracy of the determination of the travel lane deviation of the steering following target vehicle is lowered.

On the other hand, the inventor of the present application examined the following vehicle driving support device.
That is, in this vehicle driving support device, while the steering following target vehicle is moving from the position corresponding to the host vehicle to the current position, the yaw angle to the white line of the steering following target vehicle is the first yaw angle of the past steering following target vehicle It is considered to change at the rate of change of θ1, and the yaw angle with respect to the white line of the steering following target vehicle is estimated. Further, the vehicle driving support device estimates the lateral velocity of the steering following target vehicle using the estimated yaw angle.

  Then, when the estimated estimated lateral speed is equal to or higher than the predetermined threshold value, the vehicle driving support device determines that the steering following target vehicle is in the situation of departing from the traveling lane. If the estimated lateral speed is smaller than the predetermined threshold value, it is determined that the steering following target vehicle does not deviate from the traveling lane.

  However, while the steering following target vehicle is moving from the current vehicle position to the current position, the rate of change of the yaw angle with respect to the white line of the steering following target vehicle may change from the first yaw angle changing rate. In this case, an error occurs in which the estimated lateral velocity becomes larger or smaller than the actual estimated lateral velocity by the change of the estimated lateral velocity corresponding to the change of the rate of change of the yaw angle.

  Therefore, it may be possible that the determination that the steering-following target vehicle deviates from the traveling lane may be delayed from the start of the actual traveling lane departure. Furthermore, if the determination that the target vehicle following the steering follows the vehicle is out of the traveling lane is excessively performed, the steering following control may be excessively stopped due to the determination. obtain.

  The present invention was made to address the problems described above. That is, one of the objects of the present invention is that it is possible to reduce the possibility that the determination that the steering following target vehicle is in a situation where it deviates from the traveling lane is delayed behind the start of the actual traveling lane departure. A vehicle driving support device (hereinafter referred to as "the present invention device") which can reduce the possibility of excessive stopping of the steering following control in accordance with the determination that the steering following target vehicle deviates from the traveling lane. Also referred to as “.”.

The apparatus according to the present invention includes a lane marking recognition unit that recognizes lane markings of a traveling lane in which the host vehicle (SV) is traveling, and (17b),
A traveling locus generating unit (10) for generating a traveling locus of a steering following target vehicle (TV) specified from among preceding vehicles traveling in front of the host vehicle;
A vehicle speed acquisition unit (17) for acquiring the vehicle speed of the target vehicle following the steering;
A traveling lane departure situation determination unit (10) that determines a departure situation of the target vehicle following the steering;
A travel control unit that executes a steering follow-up control that changes a steering angle of the host vehicle so that the host vehicle travels along a target travel line set based on at least one of the division line and the travel locus 10) and
Equipped with
The travel lane departure situation determination unit
The division line of the past steering follow-up target vehicle (TVp) and the past when the longitudinal position is the same as the subject vehicle and the lateral position exists at the subject vehicle corresponding position at the position on the traveling track A first distance (DL1) in the lane width direction between the steering following target vehicle, a first yaw angle (θ1) with respect to the section line of the past steering following target vehicle, and a unit time of the first yaw angle Acquiring a parameter consisting of a first yaw angle change rate (θ1 ′) which is a change amount of the second curve, based on the recognized dividing line and the traveling locus (step 625);
The acquired parameters, the vehicle speed, and a first travel time taken for the target vehicle following the steering to move to the position of the target vehicle following the steering, are represented by the following (first mathematical formula) to (third mathematical formula) Calculating a second distance in the lane width direction between the steering following target vehicle and the lane line and an estimated lateral velocity of the steering following target vehicle (step 630).
By dividing the calculated second distance by the calculated estimated lateral speed, a departure prediction time until the steering following target vehicle reaches the white line is calculated (step 630).

（ＤＬ２：第２距離、ＤＬ１：第１距離、ｖ：操舵追従目標車両の車速、θ１：第１ヨー角、θ１’：第１ヨー角変化率、Ｔｘ２：第１移動時間）

θ2＝θ1+(θ１’×Ｔｘ２)・・・（第２数式）
（θ２：第２ヨー角、θ１：第１ヨー角、θ１’：第１ヨー角変化率、Ｔｘ２：第１移動時間）

ｖ２＝ｖ×θ２・・・（第３数式）
（ｖ２：推定横速度、ｖ：操舵追従目標車両の車速、θ２：第２ヨー角）

(DL2: second distance, DL1: first distance, v: vehicle speed of steering target vehicle, θ1: first yaw angle, θ1 ′: first yaw angle change rate, Tx2: first movement time)

θ2 = θ1 + (θ1 ′ × Tx2)... (second equation)
(Θ2: second yaw angle, θ1: first yaw angle, θ1 ′: first yaw angle change rate, Tx2: first movement time)

v2 = v × θ2 (third equation)
(V2: estimated lateral speed, v: vehicle speed of the target vehicle following the steering, θ2: second yaw angle)

  The second distance used for the determination, estimated lateral speed, and departure prediction time (hereinafter referred to as “determination parameter”) are steering followings while the steering following target vehicle moves from the vehicle corresponding position to the current position. The change rate of the yaw angle with respect to the white line of the target vehicle is calculated assuming that it is constant and does not change from the first yaw change rate θ1 ′. However, the rate of change of the yaw angle with respect to the above-mentioned white line of the actual steering following target vehicle may be changing by increasing or decreasing from the first yaw angle change rate.

  At this time, when the steering follow-up target vehicle moves from the host vehicle corresponding position to the current position, the rate of change of the yaw angle with respect to the white line of the actual steering follow-up target vehicle changes from the first yaw angle change rate. The determination parameter has an error with respect to the actual determination parameter by the change of the first yaw angle change rate.

  Therefore, if the traveling lane departure situation of the steering following target vehicle is determined based on the determination parameter, it is determined that the steering following target vehicle is in the situation of departing from the traveling lane is the start of the actual traveling lane departure. It may be behind time. Furthermore, if the determination that the steering follow-up target vehicle deviates from the traveling lane is excessively performed, the steering follow-up control may be excessively stopped with the determination.

Therefore, the traveling lane departure traveling condition determination unit
First deviation completion determination condition that the second distance is equal to or less than a first threshold distance, second deviation completion determination condition that the estimated lateral velocity is equal to or more than a first threshold lateral velocity, and the deviation prediction time When at least one of the third departure completion determination conditions that is equal to or less than the first threshold time is satisfied, it is determined that the steering following target vehicle is in the departure completion status (a determination of “Yes” in step 635) ,
When the steering following target vehicle is not in the deviation completion state (determination of "No" in step 636), the second distance is equal to or less than a second threshold distance which is larger than the first threshold distance. A first departure start determination condition, a second departure start determination condition that the estimated lateral velocity is equal to or higher than a second threshold lateral velocity that is a value smaller than the first threshold lateral velocity, and the deviation prediction time When at least one of the third departure start determination conditions that is equal to or less than the second threshold time that is a value greater than one threshold time is satisfied, it is determined that the steering following target vehicle is in the departure start situation (step 640). Judgment of "Yes"),
If the steering follow-up target vehicle is not in the departure completion situation or the departure start situation, it is determined that the steering follow-up target vehicle is in the traveling lane situation (determination "No" in step 645, step 640). Judgment with "No" in,),
The travel control unit is
When the steering following target vehicle is in the traveling lane state (determination of "No" in step 645, determination of "No" in step 640), the magnitude of the steering angle is the first steering angle guard The first steering angle size restriction processing for restricting the steering angle so as not to exceed the value, and the magnitude of the steering angular velocity which is the change amount per unit time of the steering angle exceeds the first steering angular velocity guard value The first steering follow-up control that performs the steering follow-up control is performed by performing the first limit process including at least one of the first steering angular velocity magnitude restriction process that limits the steering angle so as not to occur (step 645) Step 655),
If the steering-following target vehicle is in the departure start situation (determination of "Yes" in step 640), the second steering angle guard value having the magnitude of the steering angle smaller than the first steering angle guard value is A second steering angle size limiting process which is a process for limiting the steering angle so as not to exceed and which replaces the first steering angle size limiting process, and a size of the steering angular velocity is the first steering angular velocity guard At least one of a second steering angular velocity magnitude limiting process for limiting the steering angle so as not to exceed a second steering angular velocity guard value smaller than a value, and replacing the first steering angular velocity magnitude restriction process; The second limit processing including the second limit processing is performed (step 650), and the second steering follow-up control that performs the steering follow-up control is performed (step 655).
When the steering following target vehicle is in the deviation completion state (determination of "Yes" in step 635), the steering following control is stopped.

  As a result, it is possible to reduce the possibility that the determination that the steering following target vehicle deviates from the traveling lane may be delayed from the start time of the actual traveling lane departure, and the steering following control involved in the determination. It is possible to reduce the possibility of excessive stopping of the

  In the above description, in order to facilitate understanding of the present invention, the names and / or symbols used in the embodiments are attached in parentheses to the configuration of the invention corresponding to the embodiments described later. However, each component of the present invention is not limited to the embodiment defined by the above-mentioned name and / or code.

FIG. 1 is a schematic block diagram of a vehicle driving support device according to an embodiment of the present invention. FIG. 2 is a plan view for explaining the lane keeping control. FIG. 3A is a plan view for explaining the lane keeping control. FIG. 3B is an equation for explaining the relationship between the coefficient of the cubic function of the traveling locus and the curvature and the like. FIG. 3C is an equation for explaining the relationship between the coefficient of the cubic function of the traveling locus and the curvature and the like. FIG. 4 is a plan view of a road and a vehicle for explaining the operation of the vehicle driving support device according to the embodiment of the present invention. FIG. 5A is a table showing the relationship between the threshold of the determination parameter, the traveling lane departure condition, and the content of the steering follow-up control according to the determination result. FIG. 5B is a table showing the relationship between the threshold of the determination parameter, the traveling lane departure condition, and the content of the steering follow-up control according to the determination result. FIG. 5C is a table showing the relationship between the threshold of the determination parameter, the traveling lane departure condition, and the content of the steering follow-up control according to the determination result. FIG. 6 is a flowchart showing a routine executed by the CPU of the driving support ECU provided in the vehicle driving support device according to the embodiment of the present invention.

  Hereinafter, a vehicle driving support device (hereinafter, also referred to as a “present implementation device”) according to an embodiment of the present invention will be described with reference to the drawings. The present implementation device is also a vehicle travel control device. In all the drawings of the embodiment, the same or corresponding parts are denoted by the same reference numerals.

(Constitution)
The present embodiment is applied to a vehicle (automobile) as shown in FIG. The vehicle to which the present implementation device is applied may be referred to as "own vehicle" in order to distinguish it from other vehicles. The present implementation device includes a driving support ECU 10, an engine ECU 30, a brake ECU 40, a steering ECU 60, a meter ECU 70, an alarm ECU 80, and a navigation ECU 90. In the following, the driving support ECU 10 is also simply referred to as “DSECU”.

  These ECUs are electric control units (Electric Control Units) each having a microcomputer as a main part, and are connected to be able to transmit and receive information mutually via a CAN (Controller Area Network) not shown. The microcomputer includes a CPU, a ROM, a RAM, a non-volatile memory, an interface I / F, and the like. The CPU implements various functions by executing instructions (programs, routines) stored in the ROM. Some or all of these ECUs may be integrated into one ECU.

  The DSECU is connected to the sensors (including switches) listed below to receive detection signals or output signals of those sensors. Each sensor may be connected to an ECU other than the DSECU. In that case, the DSECU receives the detection signal or output signal of the sensor from the ECU to which the sensor is connected via the CAN.

The accelerator pedal operation amount sensor 11 detects an operation amount (accelerator opening degree) of the accelerator pedal 11a of the host vehicle, and outputs a signal representing an accelerator pedal operation amount AP.
The brake pedal operation amount sensor 12 detects an operation amount of the brake pedal 12a of the host vehicle, and outputs a signal representing the brake pedal operation amount BP.

The steering angle sensor 14 detects a steering operation angle which is a rotation angle of the steering wheel SW of the host vehicle, and outputs a signal representing the steering operation angle θ.
The steering torque sensor 15 detects a steering torque applied to the steering shaft US of the host vehicle by the operation of the steering wheel SW, and outputs a signal representing the steering torque Tra.
The vehicle speed sensor 16 detects the traveling speed (vehicle speed) of the host vehicle and outputs a signal representing the vehicle speed SPD.

  The ambient sensor 17 includes a radar sensor 17a, a camera sensor 17b, and a target recognition unit 17c. The surrounding sensor 17 is configured to obtain information on at least a road ahead of the host vehicle and a three-dimensional object present on the road. The three-dimensional object represents, for example, moving objects such as pedestrians, bicycles and automobiles, and fixed objects such as telephone poles, trees and guardrails. Hereinafter, these three-dimensional objects may be referred to as "targets".

  The surrounding sensor 17 detects the presence or absence of a target based on the information detected from a three-dimensional object by at least one of the radar sensor 17a and the camera sensor 17b, the target ID of the recognized target (n), the vertical distance Dfx (n) , Information on a target (n) including the lateral position Dfy (n), the relative velocity Vfx (n), the relative lateral velocity Vfy (n), the vehicle speed v, etc. (hereinafter referred to as "target information") It is designed to calculate and output.

  In addition, the surrounding sensor 17 acquires these values based on the predetermined xy coordinate (refer FIG. 2). The x-axis extends along the front-rear direction of the host vehicle SV so as to pass through the widthwise center position of the front end of the host vehicle SV, and is a coordinate axis having the front as a positive value. The y-axis is a coordinate axis orthogonal to the x-axis and having the left direction of the host vehicle SV as a positive value. The origin of the x axis and the origin of the y axis are center positions in the width direction of the front end of the vehicle SV. The x-coordinate position of the x-y coordinate is called a vertical distance Dfx, and the y-coordinate position is called a horizontal position Dfy.

The vertical distance Dfx (n) of the target (n) is the front end of the host vehicle SV and the rear end of the target (n) (for example, a front vehicle which is another vehicle traveling in the front region of the host vehicle SV) The signed distance in the central axis direction (x-axis direction) of the host vehicle SV between them.
The lateral position Dfy (n) of the target (n) is orthogonal to the central axis of the own vehicle at "the central position of the target (n) (for example, the center position in the vehicle width direction of the rear end of the front vehicle)" It is a signed distance in the direction (y-axis direction).
The relative velocity Vfx (n) of the target (n) is the difference (= Vs-Vj) between the velocity Vs of the target (n) and the velocity Vj (= SPD) of the vehicle. The velocity Vs of the target (n) is the velocity of the target (n) in the central axis direction (x-axis direction) of the vehicle.
The relative lateral velocity Vfy (n) of the target (n) is the velocity (signed velocity) in the direction (y-axis direction) orthogonal to the central axis of the host vehicle at the central position of the target (n).

  The radar sensor 17a shown in FIG. 1 includes a radar wave transmitting / receiving unit and a processing unit. The radar wave transmitting / receiving unit emits, for example, a millimeter wave band radio wave (hereinafter referred to as “millimeter wave”) at least in the peripheral region of the vehicle SV including at least the front region of the vehicle SV. A wave receives a reflected wave generated by being reflected by a portion (immediately, a reflection point) of a solid. The radar sensor 17a may be a radar sensor that uses radio waves (radar waves) in frequency bands other than the millimeter wave band.

  The processing unit of the radar sensor 17a uses reflection point information including the phase difference between the transmitted millimeter wave and the received reflected wave, the attenuation level of the reflected wave, the time from the transmission of the millimeter wave to the reception of the reflected wave, and the like. Based on the determination of the presence or absence of a target.

  Furthermore, the processing unit of the radar sensor 17a determines the vertical distance Dfx of the target, the heading θp of the target with respect to the host vehicle SV, and the host vehicle SV, based on the reflection point information of the reflection points belonging to the recognized target. The relative velocity Vfx with the target, the vehicle speed v of the target, and the like (hereinafter referred to as “radar sensor detection information”) are calculated.

  The camera sensor 17 b includes a stereo camera and an image processing unit. The stereo camera captures the scenery of the “left side area and the right side area” in front of the host vehicle SV and acquires a pair of left and right image data.

The image processing unit determines the presence or absence of a target present in the imaging area based on the photographed left and right pair of image data. When it is determined that a target exists, the image processing unit determines the azimuth θ _p of the target, the vertical distance Dfx of the target, the relative velocity Vfx between the vehicle SV and the target, etc. Camera sensor detection information) is calculated.

  The target recognition unit 17 c is connected in a communicable state with the processing unit of the radar sensor 17 a and the image processing unit of the camera sensor 17 b, and receives “radar sensor detection information” and “camera sensor detection information”. It has become. The target recognition unit 17c uses the “target ID, vertical distance Dfx (n) of the target (n) recognized using at least one of the“ radar sensor detection information ”and the“ camera sensor detection information ”, and the horizontal distance Target information including the position Dfy (n) and the relative velocity Vfx (n) is determined (acquired). The target recognition unit 17c transmits the determined target information to the DSECU each time a predetermined time has elapsed.

  Furthermore, the image processing unit of the camera sensor 17b is based on the pair of left and right image data, lane markings (such as lane markers, hereinafter simply referred to as "white lines") such as white lines on the left and right of the road. recognize. Then, the image processing unit determines the shape (for example, curvature radius) of the host vehicle SV traveling lane, which is the lane in which the host vehicle SV is traveling, and the positional relationship between the host vehicle SV traveling lane and the host vehicle SV for a predetermined time. It is calculated and sent to DSECU every time e. The positional relationship between the host vehicle SV traveling lane and the host vehicle SV is, for example, a lane between a central position (that is, a central line) of the left white line and the right white line of the host vehicle traveling lane and the central position in the vehicle width direction of the host vehicle SV. It is represented by the distance in the width direction, the angle between the direction of the center line and the x-axis direction of the vehicle SV (that is, the yaw angle), or the like.

  Information indicating the shape of the host vehicle travel lane, the positional relationship between the host vehicle travel lane and the host vehicle in the lane width direction, and the like may be provided from the navigation ECU 90.

  The operation switch 18 shown in FIG. 1 is a switch operated by the driver of the host vehicle SV. The driver can select whether to execute lane keeping control including steering follow-up control described later by operating the operation switch 18. Furthermore, the driver can select whether to execute an inter-vehicle distance control (following inter-vehicle distance control) described later by operating the operation switch 18.

  The yaw rate sensor 19 detects a yaw rate of the host vehicle SV and outputs an actual yaw rate YRt.

  The engine ECU 30 is connected to the engine actuator 31. The engine actuator 31 is an actuator for changing the operating state of the internal combustion engine 32, and includes at least a throttle valve actuator for changing the opening degree of the throttle valve. Engine ECU 30 can change the torque generated by internal combustion engine 32 by driving engine actuator 31, thereby controlling the driving force of host vehicle SV to change the acceleration of host vehicle SV. it can.

  The brake ECU 40 is connected to the brake actuator 41. The brake actuator 41 is provided in a hydraulic circuit between a master cylinder (not shown) and the friction brake mechanism 42 provided on the left and right front and rear wheels. The brake actuator 41 adjusts the hydraulic pressure of the hydraulic fluid supplied to the wheel cylinder built in the brake caliper 42b of the friction brake mechanism 42 according to the instruction from the brake ECU 40, and the hydraulic pressure of the hydraulic fluid supplied to the wheel cylinder is not shown. To generate friction braking force. Accordingly, by controlling the brake actuator 41, the brake ECU 40 can control the braking force of the host vehicle SV to change the acceleration (in this case, the deceleration) of the host vehicle SV.

  The steering ECU 60 is a control device of a known electric power steering system, and is connected to the motor driver 61. The motor driver 61 is connected to the steering motor 62. The steering motor 62 is incorporated in a "steering mechanism including a steering wheel SW, a steering shaft US, a steering gear mechanism (not shown) and the like". The steering motor 62 generates a torque by the power supplied from the motor driver 61, and can generate a steering assist torque or steer the left and right steered wheels by this torque. That is, the steering motor 62 can change the steering angle (also referred to as “steering angle” or “steering angle”) of the host vehicle SV.

  The meter ECU 70 is connected to a digital display meter not shown. Furthermore, the meter ECU 70 is also connected to the hazard lamp 71 and the stop lamp 72, and can change the lighting state of these according to an instruction from the DSECU.

  The alarm ECU 80 is connected to the buzzer 81 and the display 82. The alarm ECU 80 can alert the driver by ringing the buzzer 81 in response to an instruction from the DSECU, and makes the indicator 82 light a mark for alerting (for example, a warning lamp) can do.

  The navigation ECU 90 is connected to a GPS receiver 91 for receiving a GPS signal for detecting the current position of the vehicle SV, a map database 92 storing map information and the like, a touch panel display 93 and the like. The navigation ECU 90 determines the position of the vehicle SV at the current time based on the GPS signal (in the case where the vehicle SV is traveling on a road having a plurality of lanes, which lane the vehicle SV is traveling) Identify information). The navigation ECU 90 performs various arithmetic processing based on the position of the vehicle SV and the map information and the like stored in the map database 92, and performs route guidance using the display 93 based on the arithmetic processing result.

<Overview of operation>
Next, an outline of the operation of the present embodiment will be described. The DSECU of this embodiment can execute inter-vehicle distance control and lane keeping control. Hereinafter, “inter-vehicle distance control and lane keeping control” will be described.

<Inter-vehicle distance control (ACC: adaptive cruise control)>
The inter-vehicle distance control (that is, the following inter-vehicle distance control) is an inter-vehicle distance between the own vehicle SV and a forward vehicle traveling in front of the own vehicle SV in the area ahead of the own vehicle SV based on target information. (That is, control is performed to cause the own vehicle SV to follow the preceding vehicle while maintaining the longitudinal distance Dfx (n) of the preceding vehicle with respect to the own vehicle SV at a predetermined target inter-vehicle distance. The following inter-vehicle distance control itself is known (see, for example, JP-A-2014-148293, JP-A-2006-315491, JP-A-4172434, and JP-A-4929777). Therefore, it will be briefly described below.

  The DSECU executes inter-vehicle distance control when inter-vehicle distance control is requested by the operation of the operation switch 18.

  First, when the inter-vehicle distance control is requested, the DSECU calls a vehicle to be followed based on the target information of the target (n) acquired by the surrounding sensor 17 (hereinafter referred to as “inter-vehicle distance target vehicle” Identified). More specifically, the DSECU determines (specifies) an inter-vehicle distance target vehicle among other vehicles (that is, forward vehicles) traveling in the front region of the host vehicle SV as follows.

Step 1A: The DSECU acquires, from the vehicle speed sensor 16 and the yaw rate sensor 19, the vehicle speed SPD of the vehicle SV and the yaw rate Yrt of the vehicle SV, which are motion state quantities of the vehicle SV.
Step 2A: The DSECU predicts the traveling path of the host vehicle SV in xy coordinates based on the vehicle speed SPD and the yaw rate Yrt.
Step 3A: The DSECU determines that the predicted absolute value of the distance in the lane width direction from the travel route of the own vehicle SV predicted from among other vehicles (ie, forward vehicles) having a positive value of the vertical distance Dfx (n) The other vehicle within the first reference threshold of is determined (selected / set) as an inter-vehicle distance target vehicle (a). The first reference threshold is set to decrease as the vertical distance Dfx (n) increases. When there are a plurality of other vehicles determined, the DSECU specifies the other vehicle with the minimum vertical distance Dfx (n) as the target inter-vehicle distance (a).

  When the inter-vehicle distance target vehicle (a) is specified, the DSECU calculates the target acceleration Gtgt in accordance with either of the following equations (1) and (2). In the equations (1) and (2), Vfx (a) is the relative velocity of the target inter-vehicle distance (a), k1 and k2 are predetermined positive gains (coefficients), and ΔD1 is the target of inter-vehicle distance An inter-vehicle deviation (ΔD1 = Dfx (a) −Dtgt) obtained by subtracting the “target inter-vehicle distance Dtgt” from the longitudinal distance Dfx (a) of the vehicle (a). The target inter-vehicle distance Dtgt is calculated by multiplying the target inter-vehicle time Ttgt set by the driver using the operation switch 18 by the vehicle speed SPD of the host vehicle SV (that is, Dtgt = Ttgt · SPD).

When the value (k1 · ΔD1 + k2 · Vfx (a)) is positive or “0”, the DSECU determines the target acceleration Gtgt using the following equation (1). ka1 is a positive gain (coefficient) for acceleration, and is set to a value of “1” or less.
When the value (k1 · ΔD1 + k2 · Vfx (a)) is negative, the DSECU determines the target acceleration Gtgt using the following equation (2). kd1 is a positive gain (coefficient) for deceleration, and is set to "1" in this example.

Gtgt (for acceleration) = ka1 · (k1 · ΔD1 + k2 · Vfx (a)) (1)
Gtgt (for deceleration) = kd1 · (k1 · ΔD1 + k2 · Vfx (a)) (2)

  When the target vehicle distance can not be specified due to the absence of the preceding vehicle, the DSECU is configured such that the vehicle speed SPD of the host vehicle SV matches the "target vehicle speed set using the operation switch 18". Then, the target acceleration Gtgt is determined based on the target vehicle speed and the vehicle speed SPD.

  The DSECU controls the engine actuator 31 using the engine ECU 30 so that the acceleration of the host vehicle SV matches the target acceleration Gtgt, and controls the brake actuator 41 using the brake ECU 40 as necessary.

<Lane maintenance control>
When the lane keeping control is requested by the operation of the operation switch 18, the DSECU executes the lane keeping control only during the execution of the inter-vehicle distance control. Lane maintenance control mainly includes section lane maintenance control and steering follow-up control.

  Section lane maintenance control determines a target travel line (target travel path) based on the division lines such as the white line and the yellow line, and the steering angle of the host vehicle SV so that the host vehicle SV travels along the target travel line. Control to adjust the Partition lane maintenance control may be referred to as LTC (Lane Trace Control). In the following, the dividing lines are described as white lines.

  The steering follow-up control identifies one of the preceding vehicles as the steering follow-up target vehicle, and the steering angle of the own vehicle SV so that the own vehicle SV travels along the target traveling line according to the traveling trajectory of the steering follow-up target vehicle. Control to adjust the Steering follow-up control and section lane maintenance control may also be generically referred to as "TJA (Traffic Jam Assist)", and may be referred to as "steering support control" because the control assists the driver's steering operation. . Hereinafter, the description will be added in the order of section lane maintenance control and then steering follow-up control.

<< Section Lane Maintenance Control >>
If at least one of the left white line and the right white line is recognized by the camera sensor 17b over a predetermined distance in the forward direction of the host vehicle SV, the DSECU determines a target travel line based on at least one of the left white line and the right white line. Set Ld.

  More specifically, when both the left white line and the right white line are recognized in the forward direction of the host vehicle SV over a predetermined distance, the DSECU measures the center position in the lane width direction of the left white line and the right white line. The line passing through (ie, the center line) is set as the target travel line Ld.

  On the other hand, when only one white line of the left white line and the right white line is recognized over the predetermined distance in the forward direction of the host vehicle SV, the DSECU recognizes the recognized white line and the left white line. The position of the unrecognized white line (the other white line) is estimated based on the lane width acquired when both the right white line and the right white line were recognized. Then, the DSECU sets the center line of the recognized one white line and the estimated other white line as the target travel line Ld.

  Furthermore, the steering motor is controlled so that the DSECU maintains the lateral position of the host vehicle SV (that is, the position of the host vehicle SV in the lane width direction with respect to the host vehicle travel lane) in the vicinity of the set target travel line Ld. The steering angle of the host vehicle SV is changed by applying a steering torque to the steering mechanism using 62, thereby supporting the driver's steering operation (for example, Japanese Patent Application Laid-Open Nos. 2008-195402 and 2009-). 190464, JP-A-2010-6279, and Patent No. 4349210, etc.). A specific steering control method will be described later.

<< Steering tracking control >>
If there is no white line recognized over a predetermined distance in the forward direction of the host vehicle SV, the DSECU is suitable as a steering following target vehicle among other vehicles (forward vehicles) traveling in the front region of the host vehicle SV. Select a vehicle. Then, the DSECU generates a traveling locus of the steering following target vehicle (hereinafter, also referred to as “preceding vehicle locus”), and the host vehicle SV travels along the target traveling line determined based on the preceding vehicle locus. The steering torque is applied to the steering mechanism to change the steering angle. In the present example, the DSECU sets the preceding vehicle trajectory itself as the target travel line Ld. However, the DSECU may set a line displaced in the lane width direction by a predetermined distance from the preceding vehicle trajectory as the target travel line Ld.

The steering follow-up control will be described in detail below.
As shown in FIG. 2, the DSECU sets the forward vehicle, which is the target (n) for which the leading vehicle trajectory is to be created, as the steering following target vehicle TV. The method of setting the steering following target vehicle TV will be described in detail later. The DSECU creates a traveling locus L1 based on "target information (position) information of the steering following target vehicle TV" obtained each time a predetermined measurement time has elapsed.

  As shown in FIG. 3 (A), the traveling locus L1 is determined by the following (3) in the x-y coordinates described above with the center in the width direction of the front end of the vehicle SV at the current position of the vehicle SV as the origin. It is known that the curve is accurately approximated by a curve represented by a cubic function of the equation).

y = (1/6) Cv 'x ³ + (1/2) Cv x ² + θv x + dv (3)

Cv ′: curvature change rate (curvature change amount per unit distance (Δx) at an arbitrary position on the curve (x = x0, x0 is an arbitrary value)).
Cv: When the steering following target vehicle TV is present at the current position (x = 0) of the host vehicle SV (ie, the steering following target vehicle TV is present at the position (x = 0, y = dv) Curvature of the traveling locus L1).
θv: Direction of the traveling locus L1 (the tangential direction of the traveling locus L1) when the steering following target vehicle TV exists at the current position (x = 0) of the own vehicle SV and the traveling direction of the own vehicle SV (x axis Angular deviation with +). The angular deviation θv is also referred to as “yaw angle”.
dv: a distance dv (substantially in the lane width direction) between the current position (x = 0, y = 0) of the vehicle SV and the traveling locus L1. This distance dv is also referred to as "center distance".

The above equation (3) is derived as described below. That is, as shown in FIG. 3 (B), the traveling locus L1 is set to a cubic function f (x) = ax ³ + bx ² + cx + d, and further, the relational expression shown in FIG. 3 (B) and By using the conditions, “the relationship between the coefficients (a, b, c and d) of the cubic function and the curvature etc.” shown in FIG. 3C can be derived. Therefore, when the coefficients (a, b, c and d) of the cubic function are obtained from the relationship shown in FIG. 3C, the above equation (3) is derived.

The coefficients of the first term and the second term on the right side of the equation (3) (ie, the coefficients a and b of the function f (x) have the following values (these values are also referred to as "preceding vehicle locus basic information" This can be obtained by inputting time-series data consisting of (remarked) into a Kalman filter (not shown) provided in the DSECU. "T" is time.
Distance between vehicles at time t Longitudinal distance of target vehicle Dfx = Dfx (VT) (t)
-Lateral position of the target vehicle at the time t t Dfy = Dfy (VT) (t)
The yaw rate YRt (t) of the host vehicle SV at time t, and
· Vehicle speed Vsx of the host vehicle SV at time t (= SPD (t))
The coefficients of the third and fourth terms on the right side of the equation (3) (ie, the coefficients c and d of the function f (x)) are the yaw angle θv and the center distance dv, respectively.

  The DSECU sets the created travel locus L1 to the target travel line Ld. In this case, it is possible to acquire "target travel path information necessary for lane keeping control" shown in FIG. 2 from the coefficient of the cubic function of equation (3). The target travel road information is, as described later, the curvature Cv of the travel locus L1, the yaw angle θv with respect to the travel locus L1, and the center distance dv with respect to the travel locus L1.

  More specifically, the DSECU acquires information (necessary creation information) necessary for creating the traveling locus L1. The information necessary for creating the traveling locus L1 includes the coordinate value of the steering following target vehicle TV in xy coordinates, the vehicle speed SPD of the host vehicle SV, the yaw rate YRt of the host vehicle SV, and the like. The DSECU acquires coordinate values in the x-y coordinates of the steering following target vehicle TV based on the target information on the steering following target vehicle TV. The DSECU acquires the vehicle speed SPD of the host vehicle SV from the vehicle speed sensor 16, and acquires the yaw rate YRt of the host vehicle SV from the yaw rate sensor 19.

  The DSECU generates the travel locus L1 represented by the equation (3) by inputting the acquired creation necessary information to the Kalman filter. The DSECU sets the generated traveling locus L1 to the target traveling line Ld. Furthermore, the DSECU is required for steering following control when the traveling locus L1 is set to the target traveling line Ld based on the coefficient of the cubic function of the equation (3) and the relational expression shown in FIG. Information (hereinafter, sometimes referred to as "target travel path information") is acquired. The target travel path information includes the curvature Cv of the travel locus L1, the yaw angle θv with respect to the travel locus L1, and the center distance dv with respect to the travel locus L1.

The DSECU calculates the target steering angle θ * by applying the curvature Cv, the yaw angle θv and the center distance dv to the following equation (4) each time a predetermined time has elapsed. In the equation (4), Klta1, Klta2 and Klta3 are predetermined control gains. Furthermore, the DSECU controls the steering motor 62 using the steering ECU 60 so that the actual steering angle θ matches the target steering angle θ *. By the above, steering control by steering following control is performed.

θ * = Klta1 · Cv + Klta2 · θv + Klta3 · dv (4)

Note that the DSECU may calculate the target yaw rate YRc * by applying the curvature Cv, the yaw angle θv, and the center distance dv to the following equation (5) each time a predetermined time elapses. In this case, the DSECU calculates a target steering torque Tr * for obtaining the target yaw rate YRc * using the look-up table, based on the target yaw rate YRc * and the actual yaw rate YRt. Then, the DSECU controls the steering motor 62 using the steering ECU 60 so that the actual steering torque Tra matches the target steering torque Tr *. Also by the above, steering control by steering following control is performed. As understood from the above, if the target running path information can be obtained, the DSECU executes steering following control in the case where the running locus L1 is set to the target running line Ld without calculating the target running line Ld itself. it can.

YRc * = K1 × dv + K2 × θv + K3 × Cv (5)

  The DSECU also uses the above equation (4) or (5) when executing the above-described section lane maintenance control. More specifically, the DSECU sets the curvature CL of the target travel line Ld (that is, the center line of the host vehicle travel lane) set based on at least one of the left white line and the right white line, and the vehicle width of the host vehicle SV. The distance dL between the central position in the direction and the target travel line Ld in the y-axis direction (substantially the road width direction) and the deviation between the direction of the target travel line Ld (tangential direction) and the traveling direction of the host vehicle SV The angle θL (yaw angle θL) is calculated.

  Then, the DSECU calculates the target steering angle θ * by replacing dv with dL, replacing θv with θL, and replacing Cv with CL in equation (4) (or equation (5)). The steering motor 62 is controlled such that the actual steering angle θ matches the target steering angle θ *. Thus, the steering control based on the block lane maintenance control is performed.

  The DSECU can not set the target travel line Ld based on at least one of the left white line and the right white line, and can not generate a preceding vehicle locus (including the case where it is not possible to determine the steering following target vehicle). Cancel the execution of maintenance control. That is, in this case, the DSECU does not perform lane keeping control.

(Upper limit guard value of steering angle and steering angular velocity)
By the way, in the lane keeping control, the DSECU limits the steering angle so that the magnitude of the steering angle does not exceed the upper limit guard value (hereinafter also referred to as “steering angle guard value”). Furthermore, in the lane keeping control, the steering angular velocity is limited so that the magnitude of the steering angular velocity does not exceed the upper limit guard value (hereinafter also referred to as “steering angular velocity guard value”). As a result, the possibility of sudden change of the behavior of the host vehicle SV due to the change of the steering angle is reduced, so that the running stability of the host vehicle SV is secured.
The above is the outline of the lane keeping control.

  Next, referring to FIG. 4, “steering follow control in accordance with the deviation of the steering following target vehicle from the travel lane” executed by the DSECU of the present embodiment will be described. As shown in FIG. 4, the DSECU is currently performing steering control such that the host vehicle SV follows the traveling locus L1 of the target vehicle TV to follow.

  At this time, the DSECU acquires a determination parameter that represents the positional relationship between the steering follow-up target vehicle TV and the white line LW. The DSECU determines, using the acquired determination parameter, whether the steering follow-up target vehicle TV is in a departure completion situation, a departure start situation, or a situation in a traveling lane.

  Then, the DSECU performs the steering follow-up control or the steering follow-up control according to the determination result in accordance with the determination result.

  Specifically, the DSECU determines that the steering-following target vehicle TV (ie, the past steering-following target) exists at a position on the traveling locus L1 corresponding to the position of the host vehicle SV (the host vehicle corresponding position). The following 1st parameter which acquired the physical relationship of vehicles TVp) and white line LW is acquired. The "vehicle-corresponding position" is a position where the vertical distance is the same as the vertical distance of the vehicle SV, and the horizontal position is on the traveling locus L1. The lateral position of the host vehicle corresponding position is a value that can be obtained by substituting the vertical distance of the host vehicle SV for the variable x of the equation (3) representing the traveling locus L1.

(1st parameter)
First distance DL1: distance in the lane width direction between the target vehicle TVp and the white line LW in the past (that is, distance in the lane width direction between the vehicle corresponding position and the white line LW)
The DSECU subtracts the distance DL3 in the lane width direction between the host vehicle SV and the host vehicle corresponding position from the distance DL4 in the lane width direction between the host vehicle SV and the white line LW (DL1 = DL4-DL3). , And the first distance DL1 can be obtained.
· First yaw angle θ1: Yaw angle with respect to the white line LW of the target vehicle TVp to follow in the past DSECU is the yaw angle θ3 with respect to the travel locus L1 of the target vehicle TV following the host vehicle SV The first yaw angle θ1 can be obtained by calculating the difference with the θ4 (first yaw angle θ1 = θ3−θ4).
First yaw angle change rate θ1 ′: change rate of first yaw angle θ1 The DSECU calculates the first yaw angle θ1 change amount per unit time (θ1 ′ = θ1 / dt) to calculate the first yaw angle change rate θ1 ′. The angular change rate θ1 ′ can be acquired.

  Furthermore, the DSECU sets the first parameter (the first distance DL1, the first yaw angle θ1 and the first yaw angle change rate θ1 ′), the vehicle speed v of the steering following target vehicle TV, and the steering following target vehicle corresponding position. Using the first movement time Tx2 (= “inter-vehicle distance / steering-following target vehicle TV's vehicle speed v”) required to move from the position to the current position using the following (first equation) to (third equation) A second yaw angle θ2 that is a yaw angle with respect to the white line LW of the follow-up target vehicle TV, and a second parameter (determination parameter) below which estimates the positional relationship between the steer-following target vehicle TV and the white line LW are acquired.

(Judgment parameter)
Second distance DL2: Distance in the lane width direction between the steering following target vehicle TV and the white line LW Estimated lateral speed v2: Estimated lateral speed of the steering following target vehicle TV Ta: Departing prediction time Ta: Departing prediction time Ta = Prediction time until the steering following target vehicle TV calculated at the second distance DL2 / estimated lateral speed v2 reaches the white line LW

（ＤＬ２：第２距離、ＤＬ１：第１距離、ｖ：操舵追従目標車両の車速、θ１：第１ヨー角、θ１’：第１ヨー角変化率、Ｔｘ２：第１移動時間）

θ2＝θ1+(θ１’×Ｔｘ２)・・・（第２数式）
（θ２：第２ヨー角、θ１：第１ヨー角、θ１’：第１ヨー角変化率、Ｔｘ２：第１移動時間）

ｖ２＝ｖ×θ２・・・（第３数式）
（ｖ２：推定横速度、ｖ：操舵追従目標車両の車速、θ２：第２ヨー角）

(DL2: second distance, DL1: first distance, v: vehicle speed of steering target vehicle, θ1: first yaw angle, θ1 ′: first yaw angle change rate, Tx2: first movement time)

θ2 = θ1 + (θ1 ′ × Tx2)... (second equation)
(Θ2: second yaw angle, θ1: first yaw angle, θ1 ′: first yaw angle change rate, Tx2: first movement time)

v2 = v × θ2 (third equation)
(V2: estimated lateral speed, v: vehicle speed of the target vehicle following the steering, θ2: second yaw angle)

  The DSECU uses the acquired determination parameters (the second distance DL2, the estimated lateral velocity v2, and the departure prediction time Ta) to determine the departure situation of the steering following target vehicle TV from the travel lane, and according to the determination result. The steering following control according to the determination result or the steering following control is stopped.

  Here, as the determination parameter, the rate of change of the yaw angle with respect to the white line LW of the steering following target vehicle TV while the steering following target vehicle TV moves from the host vehicle corresponding position to the current position is constant. The calculation is performed assuming that there is no change from the angular change rate θ1 ′. However, the rate of change of the yaw angle with respect to the white line LW of the actual steering follow-up target vehicle TV may be changing by increasing or decreasing from the first yaw angle change rate θ1 ′.

  At this time, while the steering following target vehicle TV moves from the vehicle corresponding position to the current position, the rate of change of the yaw angle with respect to the white line LW of the actual steering following target vehicle TV is the first yaw angle change rate θ1 ′. If it is changed, the determination parameter has an error with respect to the actual determination parameter by the change from the first yaw angle change rate θ1 ′.

  For example, when the estimated lateral velocity v2 which is one of the determination parameters is equal to or higher than the predetermined threshold velocity, it is determined that the steering following target vehicle TV is in the situation of departing from the traveling lane and deviates from the traveling lane It is assumed that the steering following control is stopped when it is determined that

  If “the change rate of the yaw angle with respect to the actual white line LW” of the actual steering follow-up target vehicle TV is gradually increasing from the first yaw angle change rate θ1 ′, the estimated lateral velocity v2 is the first yaw angle change The change in the estimated lateral velocity v2 corresponding to the increase from the rate θ1 ′ has an error smaller than the actual estimated lateral velocity. As a result, the determination that the steering follow-up target vehicle TV is in a situation of departing from the traveling lane is delayed. As a result, the stop of the steering follow-up control accompanying the start of the departure from the traveling lane of the target vehicle TV for steering follow up is delayed.

  On the other hand, when the “change rate of the yaw angle with respect to the actual white line LW” of the actual vehicle following the target vehicle TV is decreasing from the first yaw angle change rate θ1 ′, the estimated lateral velocity v2 is the first yaw angle The change in the estimated lateral velocity v2 corresponding to the decrease from the change rate θ1 ′ has an error larger than the actual estimated lateral velocity. As a result, the determination that the steering follow-up target vehicle TV is in a situation of departing from the traveling lane is excessive. As a result, the stop of the steering following control accompanying the said determination will become excessive.

  For the former, the condition (hereinafter referred to as “departure determination condition”) for determining that the steering follow-up target vehicle TV deviates from the traveling lane is set loosely (a predetermined threshold speed is set. If the actual yaw angle change rate decreases, the estimated lateral velocity v2 has an error that is larger than the actual estimated lateral velocity. It is overdetermined that it is in a situation deviating from the above. As a result, while the determination delay can be eliminated, excessive stopping of the steering following control is performed.

  In contrast to the latter, assuming that the departure judgment condition is set strictly (the predetermined threshold speed is increased), if the actual yaw angle change rate is gradually increasing, the estimated lateral velocity v2 is an actual estimation. Since an error smaller than the lateral speed occurs, the determination timing that the vehicle following the target vehicle TV deviates from the traveling lane is delayed. As a result, it is possible to reduce the possibility of excessive stopping of the steering following control, but there is a delay in the determination that the steering following target vehicle TV is in a situation where it deviates from the traveling lane.

  Therefore, as shown in FIG. 5A to FIG. 5C, the DSECU of the present embodiment sets the determination condition according to the degree of deviation (by setting two threshold values different in size). In accordance with the determined degree of departure, it is determined whether or not the steering follow-up target vehicle TV is in a departure start situation, a departure completion situation, or a situation in a traveling lane. The DSECU solves these problems by stopping steering follow-up control or steering follow-up control according to the determination result according to the determination result.

  That is, it is determined that the steering follow-up target vehicle TV is in the situation of departing from the traveling lane by loosening the determination condition of the determination that the steering follow-up target vehicle TV is in the departure start situation where the degree of departure is small. Can solve the problem of delay. Furthermore, with the determination that the steering follow-up target vehicle TV is in the departure start state, the steering follow-up control is not stopped but the guard value limitation is performed and the steering follow-up control is performed, thereby causing excessive steering. It is possible to solve the problem that the follow-up control is stopped.

  Furthermore, when the steering follow-up target vehicle TV is in the departure start situation, the accuracy along the traveling lane of the traveling locus L1 decreases, but the guard value restriction is performed, whereby the accuracy along the traveling lane of the traveling locus L1 As a result, it is possible to reduce the possibility that the running stability may be reduced due to a rapid change in the steering of the host vehicle SV.

  Furthermore, the steering follow-up target vehicle TV sets the determination condition of the determination that the degree of departure is large in the departure completion situation strictly, and the steering follow-up control according to the determination that the steering follow-up target vehicle TV is in the departure completion situation By stopping the steering wheel, it is possible to solve the problem that excessive steering following control is stopped.

  Specifically, the DSECU first determines, using the determination parameter, whether or not the steering following target vehicle TV is in a deviation completion situation.

If at least one of the following departure completion determination conditions 1 to 3 is satisfied, the DSECU determines that the steering following target vehicle TV is in the departure completion state.
Deviation completion determination condition 1: The second distance DL2 is equal to or less than the first threshold distance Dth1.
Deviation completion determination condition 2: The estimated lateral velocity v2 is equal to or greater than the first threshold lateral velocity vth1.
Deviation completion determination condition 3: The deviation prediction time Ta (= DL2 / v2) is equal to or less than the first threshold time Tth1.

  If it is determined that the steering follow-up target vehicle TV is in the departure completion state, the DSECU cancels the steering follow-up control.

  If it is determined that the steering follow-up target vehicle TV is not in the departure completion situation, the DSECU determines whether the steering follow-up target vehicle TV is in the departure start situation.

If at least one of the following departure start determination conditions 1 to 3 is satisfied, it is determined that the steering following target vehicle TV is in the departure start situation.
Deviation start determination condition 1: The second distance DL2 is equal to or less than the second threshold distance Dth2.
Deviation start determination condition 2: The estimated lateral velocity v2 is equal to or higher than the second threshold lateral velocity vth2.
Deviation start determination condition 3: The deviation prediction time Ta = DL2 / v2 is equal to or less than the second threshold time Tth2.

  The departure start determination conditions 1 to 3 are set looser than the departure completion determination conditions 1 to 3 (see FIG. 5A to FIG. 5C). That is, the second threshold distance Dth2 is set to be larger than the first threshold distance Dth1. The second threshold lateral velocity vth2 is set to be smaller than the first threshold lateral velocity vth1. The second threshold time Tth2 is set to be larger than the first threshold time Tth1. Therefore, there is a possibility that the determination that the steering following target vehicle TV is in the departure start situation may be excessively performed.

  On the other hand, when it is determined that the steering follow-up target vehicle TV is in the departure start situation, the DSECU performs the steering follow-up control by performing guard value restriction instead of stopping the steering follow-up control. That is, the DSECU reduces the upper limit guard value of the steering angle (steering angle guard value) and the upper limit guard value of the steering angular velocity (steering angular velocity guard value).

  Specifically, the DSECU sets the upper limit guard value of the steering angle and the upper limit guard value of the steering angular velocity as follows. That is, the DSECU sets the steering angle guard value to “the second steering angular velocity guard value smaller than the first steering angle guard value described later”, and the steering angular velocity guard value “than the first steering angular velocity guard value described later. It is set to a small second steering angular velocity guard value. The DSECU may set one of the steering angle guard value and the steering angular velocity guard value as described above. Then, the DSECU performs steering follow-up control.

  If the steering following target vehicle TV is not in the departure start situation, the DSECU determines that the steering following target vehicle TV is in the traveling lane situation. If it is determined that the steering follow-up target vehicle TV is in the traveling lane, the DSECU sets the steering angle guard value and the steering angular velocity guard value as follows. That is, the DSECU sets the steering angle guard value to a predetermined first steering angle guard value, and sets the steering angular velocity guard value to a predetermined first steering angular velocity guard value. The DSECU may set one of the steering angle guard value and the steering angular velocity guard value as described above. Then, the DSECU performs steering follow-up control.

<Concrete operation>
Next, the specific operation of the CPU of the DSECU (which may be simply referred to as “CPU”) will be described. The CPU executes a steering follow-up control routine shown by the flowchart of FIG. 6 each time a predetermined time (Δt) elapses. The CPU executes inter-vehicle distance control (ACC) by a routine not shown. The CPU executes the routine shown in FIG. 6 only when the inter-vehicle distance control is being performed.

  Therefore, when the inter-vehicle distance control is being executed, the CPU starts the process from step 600 in FIG. 6 at a predetermined timing, proceeds to step 605, and determines whether the steering follow-up control execution condition is satisfied. Determine if

The execution condition of the steering follow-up control is satisfied, for example, when all of the conditions B1 to B3 described below are satisfied.
Condition B1: It is selected to execute lane keeping control by operating the operation switch 18.
Condition B2: The vehicle speed SPD of the host vehicle SV is equal to or higher than a predetermined lower limit vehicle speed and equal to or lower than a predetermined upper limit vehicle speed.
Condition B3: The target travel line Ld based on "at least one of the left white line and the right white line" recognized by the camera sensor 17b can not be set.

  If the execution condition of the steering follow-up control is not satisfied, the CPU determines "No" in step 605, proceeds to step 610, and cancels (cancels) the steering follow-up control. Thereafter, the CPU proceeds to step 695 to end this routine once.

  On the other hand, if the execution condition of the steering follow-up control is satisfied, the CPU makes a “Yes” determination in step 605 and proceeds to step 615 to proceed with the steering follow-up target vehicle TV for which the travel locus L1 is generated. Identify. Specifically, the CPU acquires the vehicle speed of the host vehicle SV from the vehicle speed sensor 16 and acquires the yaw rate of the host vehicle SV from the yaw rate sensor 19. The CPU predicts the traveling route of the host vehicle SV from the acquired vehicle speed and yaw rate. Then, the target closest to the preceding vehicle closest to the predicted "traveling path of the host vehicle SV" is selected as the "steering-following target vehicle TV to be generated as the traveling locus L1".

  The CPU stores target information of each target in correspondence with each target based on the target information from the surrounding sensor 17. The CPU selects the target information for the steering following target vehicle TV specified from the target information, and generates a traveling locus L1 for the steering following target vehicle TV based on the selected target information.

  Thereafter, the CPU proceeds to step 620 and determines whether or not the traveling locus L1 can be generated. Specifically, when the steering following target vehicle TV can not be specified, or the steering following target vehicle TV can be specified, the time-series data of the target information about the steering following target vehicle TV is the traveling locus If it is not sufficient to generate L1, the CPU determines that the traveling locus L1 can not be generated. Otherwise, the CPU determines that the traveling locus L1 can be generated.

  If the traveling locus L1 has been generated, the CPU makes a “Yes” determination in step 620, proceeds to step 625, and uses the camera sensor 17b based on the distance of the recognized white line sent from the camera sensor 17b. It is determined whether or not the white lines (left white line and right white line) can be recognized in the range of the first predetermined distance to the second predetermined distance. In other words, the CPU determines whether the white line can be recognized in the vicinity by the camera sensor 17b. The first predetermined distance is set smaller than the second predetermined distance.

  If the white line is recognized in the range of the first predetermined distance to the second predetermined distance by the camera sensor 17b, the CPU makes a “Yes” determination in step 625, proceeds to step 630, and proceeds to step 630. 1 distance DL 1, first yaw angle θ 1, first yaw angle change rate θ 1 ′), vehicle speed v of the steer-following target vehicle TV and steering-following target vehicle TV move from the position corresponding to the host vehicle to the current position The first movement time Tx2 is acquired.

  Thereafter, the CPU proceeds to step 635 to calculate the above-described determination parameters (the second distance DL2, the estimated lateral velocity v2 and the deviation prediction time Ta) using the first parameter and the vehicle speed v and the first movement time Tx2. In step 640, it is stabilized whether the steering following target vehicle TV is in the deviation completion state. When at least one of the departure completion determination conditions 1 to 3 described above is satisfied, the CPU determines that the steering following target vehicle TV is in the departure completion state.

  If the steering follow-up target vehicle TV is not in the deviation completion state, the CPU determines "No" in step 640 and proceeds to step 645 to determine whether the steering follow-up target vehicle TV is in the departure start state. When at least one of the departure start determination conditions 1 to 3 described above is satisfied, the CPU determines that the steering following target vehicle TV is in the departure start situation.

  If the steering following target vehicle TV is not in the departure start condition, the CPU determines "No" in step 645, proceeds to step 650, and sets the steering angle guard value θg and the steering angular velocity guard value dθg to the normal upper limit guard value. The first steering angle guard value and the first steering angular velocity guard value are respectively set. If the steering angle guard value θg and the steering angular velocity guard value dθg are already set to the first steering angle guard value and the first steering angular velocity guard value at the time of starting the processing of step 650, the CPU performs steering The angle guard value θg and the steering angular velocity guard value dθg are maintained at the first steering angle guard value and the first steering angular velocity guard value, respectively.

  Thereafter, the CPU proceeds to step 655, sets the traveling locus L1 generated based on the steering-following target vehicle in step 615 as the target traveling line Ld, and causes the host vehicle SV to travel along the target traveling line Ld. Thus, the steering angle of the host vehicle SV is controlled (steering control is performed). That is, the CPU executes steering follow-up control (first steering follow-up control). More specifically, the CPU calculates the target steering angle θ * using the equation (4) or the equation (5).

  Then, if the magnitude of the target steering angle θ * is equal to or greater than the steering angle guard value θg (θg> 0), a value equal to the steering angle guard value θg is set as the target steering angle θ *. Set as *. That is, if the target steering angle θ * is a positive value and larger than the steering angle guard value θg, the target steering angle is set to θg. Furthermore, if the target steering angle θ * is a negative value and the magnitude | θ * | is larger than the steering angle guard value θg, the target steering angle is set to “−θg”.

  Furthermore, the CPU calculates the target steering angle θ * calculated this time (that is, the current target steering angle θ * n) a predetermined time ago (in other words, the target calculated when the present routine was executed last time) The target steering angle change amount (θ * n−θ * p) is calculated by subtracting the steering angle θ * (that is, the previous target steering angle θ * p). Furthermore, the CPU divides the target steering angle change amount (θ * n−θ * p) by a predetermined time (Δt) to obtain a target steering angle change amount “(θ * n−θ * p) / Δt per unit time. To calculate

  Then, if the magnitude | (θ * n−θ * p) / Δt | of the target steering angle change amount per unit time is equal to or greater than the steering angular velocity guard value dθg (dθg> 0), the size | (θ * n Θ * n is changed so that −θ * p) / Δt | becomes equal to the steering angular velocity guard value dθg. That is, if the target steering angle change amount “(θ * n−θ * p) / Δt” per unit time is a positive value and larger than the steering angular velocity guard value dθg, the target steering angle is It is set to a value (= θ * p + dθg × Δt) obtained by adding the value dθg × Δt to The target steering angle change amount "(.theta. * N-.theta. * P) /. DELTA.t" per unit time is a negative value and the size | (.theta. * N-.theta. * P) /. DELTA.t | If it is larger than dθg, the target steering angle is set to a value obtained by subtracting the value dθg × Δt from the value θ * p (= θ * p−dθg × Δt).

  The CPU controls the steering motor 62 such that the actual steering angle θ coincides with the target steering angle θ * thus determined. As a result, the steering angle θ does not exceed the steering angle guard value θg (at this stage, the first steering angle guard value) and the magnitude of the change amount per unit time | dθ It is controlled so that / dt | does not exceed the steering angular velocity guard value dθg (at this stage, the first steering angular velocity guard value).

  On the other hand, when the steering following target vehicle TV is in the departure start situation, the CPU determines "Yes" in step 645 and proceeds to step 660, and the CPU calculates steering angle guard value θg and steering angular velocity guard value dθg. Pull down. Specifically, the CPU sets the steering angle guard value θg and the steering angular velocity guard value dθg to a second steering angle guard value and a second steering angular velocity guard value, respectively. The second steering angle guard value is smaller than the first steering angle guard value, and the second steering angular velocity guard value is smaller than the first steering angular velocity guard value. Furthermore, if the steering angle guard value and the steering angular velocity guard value are already set to the second steering angle guard value and the second steering angular velocity guard value at the time when the CPU starts the processing of step 660, the CPU performs steering The angle guard value and the steering angular velocity guard value are maintained at the second steering angle guard value and the second steering angular velocity guard value, respectively.

  Thereafter, the CPU proceeds to step 655, sets the target travel line Ld based on the travel locus L1 generated in step 615, and causes the host vehicle SV to travel the host vehicle SV along the target travel line Ld. Control the steering angle of That is, the CPU executes steering follow-up control (second steering follow-up control). As a result, the steering angle θ does not exceed the steering angle guard value θg (at this stage, the second steering angle guard value) and the magnitude of the change amount per unit time | dθ It is controlled so that / dt | does not exceed the steering angular velocity guard value dθg (at this stage, the second steering angular velocity guard value). Thereafter, the CPU proceeds to step 695 to end this routine once.

  If the steering follow-up target vehicle TV is in the deviation completion state at the time of executing the process of step 640, the CPU determines “Yes” in step 640 and proceeds to step 610 to cancel steering follow-up control ). Thereafter, the CPU proceeds to step 695 to end this routine once.

  Furthermore, at the time of executing the processing of step 620, if the traveling locus L1 is not generated, the CPU determines “No” in step 620 and proceeds to step 610 to cancel the steering follow-up control. Thereafter, the CPU proceeds to step 695 to end this routine once.

  When the white line is not recognized within the range of the first predetermined distance or more and less than the second predetermined distance by the camera sensor 17b at the time of executing the process of step 625, the CPU determines “No” in step 625 and performs step 610. To cancel steering following control. Thereafter, the CPU proceeds to step 695 to end this routine once.

  According to the present embodiment described above, the following effects can be obtained. That is, according to the present embodiment, it is determined that the steering-following target vehicle TV is in a situation where it deviates from the traveling lane (a departure start situation) by relaxing the determination condition of the determination that the departure start situation is made. Can be less likely to be delayed. Furthermore, according to the determination that the steering following target vehicle TV is in the departure start situation, the steering following control is not stopped but the guard value limitation is performed and the steering following control is performed to perform the steering following control excessively. It is possible to solve the problem of stopping the On the other hand, it is possible to promptly carry out the guard value restriction when the steering follow-up target vehicle TV is in the departure start situation without delay. Furthermore, excessive determination of the steering follow-up control can be performed by setting the determination conditions for the departure completion situation strictly and stopping the steering follow-up control in accordance with the determination that the steering follow-up target vehicle TV is in the departure completion situation. You can reduce the sex.

<Modification>
As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to the above-mentioned embodiment, Various deformation | transformation based on the technical idea of this invention are possible.

  For example, the present embodiment is configured to execute the lane keeping control only during execution of the following inter-vehicle distance control, but is configured to execute the lane maintaining control even when the following inter-vehicle distance control is not being executed. May be

  For example, the present implementation device may acquire position information, speed information, and the like of another vehicle including the steering follow-up target vehicle TV and the inter-vehicle distance target vehicle through inter-vehicle communication. Specifically, for example, the position information of the other vehicle acquired by the other vehicle by the navigation device of the other vehicle is transmitted to the own vehicle SV together with a vehicle ID signal specifying the other vehicle itself, and the own vehicle SV Based on the transmitted information, position information of the steering following target vehicle TV and / or the inter-vehicle distance target vehicle may be acquired.

  Furthermore, in the present embodiment, the method of generating the traveling locus L1 is not limited to the above-described example, and various known methods can be adopted. For example, the Kalman filter may not be used as long as it is a method that can create a curve that approximates the trajectory of the steering follow-up target vehicle TV. And this implementation apparatus should just obtain Cv, Cv ', etc. from the approximated curve.

  DESCRIPTION OF SYMBOLS 10 ... Driving assistance ECU, 16 ... Vehicle speed sensor, 17 ... Ambient sensor, 17a ... Radar sensor, 17b ... Camera sensor, 17c ... Target object recognition part, 18 ... Operation switch, 19 ... Yaw rate sensor, 60 ... Steering ECU, 61 ... Motor driver, 62: Steering motor, 80: Alarm ECU, 81: Buzzer, 82: Display, SV: Self-vehicle, TV: Steering-following target vehicle, TVp: Past steering-following target vehicle

Claims (1)

A lane marking recognition unit that recognizes lane markings of a traveling lane in which the host vehicle is traveling;
A traveling locus generating unit that generates a traveling locus of a steering following target vehicle identified from among preceding vehicles traveling ahead of the host vehicle;
A vehicle speed acquisition unit that acquires the vehicle speed of the target vehicle following the steering;
A traveling lane departure situation determination unit that determines a departure situation of the target vehicle following the steering;
A traveling control unit that executes steering follow-up control that changes a steering angle of the own vehicle so that the own vehicle travels along a target traveling line set based on the traveling locus;
Equipped with
The travel lane departure situation determination unit
The previous steering follow-up target and the previous steering follow-up target vehicle of the past steering follow-up target vehicle when the longitudinal distance is the same as the own vehicle and the lateral position exists at the own vehicle corresponding position at the position on the traveling locus. A first distance in the lane width direction between the vehicle, a first yaw angle with respect to the lane line of the past target vehicle following the steering, and a first yaw angle that is a variation per unit time of the first yaw angle. Acquiring a parameter comprising a rate of change based on the recognized division line and the traveling locus;
The acquired parameters, the vehicle speed, and a first travel time taken for the target vehicle following the steering to move to the position of the target vehicle following the steering, are represented by the following (first mathematical formula) to (third mathematical formula) Calculating a second distance in the lane width direction between the steering following target vehicle and the lane line, and an estimated lateral speed of the steering following target vehicle,
By dividing the calculated second distance by the estimated estimated lateral speed, a deviation prediction time until the steering following target vehicle reaches the white line is calculated.
First deviation completion determination condition that the second distance is equal to or less than a first threshold distance, second deviation completion determination condition that the estimated lateral velocity is equal to or more than a first threshold lateral velocity, and the deviation prediction time When at least one of the third departure completion determination conditions that is equal to or less than the first threshold time is satisfied, it is determined that the steering following target vehicle is in the departure completion status,
A first departure start determination condition that the second distance is equal to or less than a second threshold distance, which is a value greater than the first threshold distance, when the steering following target vehicle is not in the departure completion state; A second departure start determination condition that is equal to or greater than a second threshold lateral velocity, which is a value smaller than the first threshold lateral velocity, and a second threshold time where the departure prediction time is a value greater than the first threshold time When at least one of the following third departure start determination conditions is satisfied, it is determined that the steering following target vehicle is in the departure start condition,
When the steering follow-up target vehicle is not in the departure completion situation and the departure start situation, it is determined that the steering follow-up target vehicle is in a traveling lane situation;
The travel control unit is
A first steering angle size restriction process for restricting the steering angle so that the magnitude of the steering angle does not exceed a first steering angle guard value when the target vehicle following the steering is in the traveling lane state; At least one of first steering angular velocity magnitude limiting processing for limiting the steering angle so that the magnitude of the steering angular velocity, which is the variation per unit time of the steering angle, does not exceed the first steering angular velocity guard value; And performing a first steering follow-up control that performs the steering follow-up control.
A process of restricting the steering angle so that the magnitude of the steering angle does not exceed a second steering angle guard value smaller than the first steering angle guard value when the target object following the steering is in the departure start situation And a second steering angle size limiting process replacing the first steering angle size limiting process, and a magnitude of the steering angular velocity exceeds a second steering angular velocity guard value smaller than the first steering angular velocity guard value The steering follow-up is performed by performing a second limiting process including at least one of a second steering angular velocity size limiting process which is a process of limiting the steering angle so as to avoid the second steering angular velocity size limiting process instead of the first steering angular velocity size limiting process. Perform second steering following control to control
The vehicle driving support device configured to stop the steering following control when the steering following target vehicle is in the deviation completion state.

(DL2: second distance, DL1: first distance, v: vehicle speed of steering target vehicle, θ1: first yaw angle, θ1 ′: first yaw angle change rate, Tx2: first movement time)

θ2 = θ1 + (θ1 ′ × Tx2)... (second equation)
(Θ2: second yaw angle, θ1: first yaw angle, θ1 ′: first yaw angle change rate, Tx2: first movement time)

v2 = v × θ2 (third equation)
(V2: estimated lateral speed, v: vehicle speed of the target vehicle following the steering, θ2: second yaw angle)

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