JP6963211B2 - Vehicle driving support device - Google Patents

Description

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

One of the conventionally known vehicle driving support devices (hereinafter, referred to as "conventional device") generates a traveling locus of a steering tracking target vehicle selected from the vehicles in front traveling in front of the own vehicle. .. The conventional device performs steering control (steering follow-up control) so as to drive the own vehicle along a target traveling line based on the generated traveling locus.

When the steering follow-up control is performed, if the steering follow-up target vehicle deviates from the traveling lane (traveling lane), there is a high possibility that the traveling locus deviates significantly 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 traveling line using the generated traveling locus. Therefore, the conventional device determines whether or not the steering tracking target vehicle deviates from the traveling lane as follows, and when the steering tracking target vehicle deviates from the traveling lane, the conventional device determines whether or not the steering tracking target vehicle deviates from the traveling lane. Stop steering follow-up control.

In the conventional device, the steering tracking target vehicle at the time when the steering tracking 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 the vehicle and the white line is acquired using the traveling locus of the steering tracking target vehicle.

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

Next, in the conventional device, the estimated arrival time Tx1 until the past steering follow-up target vehicle reaches the white line and the movement required for the steering follow-up target vehicle to move from the own vehicle corresponding position to the current position according to the following mathematical formulas. The time Tx2 is calculated.
Expected arrival time Tx1 = "1st distance DL1 / estimated lateral speed (vehicle speed v × sin θ1 of steering tracking target vehicle)"
Travel time Tx2 = "distance between vehicles / vehicle speed v of steering tracking target vehicle"

Further, the conventional device calculates the determination time Tx (= expected arrival time Tx1-travel time Tx2) by subtracting the travel time Tx2 from the determination time Tx = expected arrival time Tx1. When the determination time Tx is smaller than the predetermined threshold value, the conventional device determines that the steering tracking target vehicle is in a state of deviating from the traveling lane, and stops the steering tracking control (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2016-101783

The conventional device is based on the premise that the yaw angle of the steering follow target vehicle with respect to the white line is constant and does not change from the first yaw angle θ1 while the steering follow target vehicle is moving from the position corresponding to the own vehicle to the current position. , The steering follow-up target vehicle is determined to deviate from the traveling lane.

However, in reality, the yaw angle of the steering follow-up target vehicle with respect to the white line may change from the first yaw angle θ1 while the steering follow-up target vehicle is moving from the position corresponding to the own vehicle to the current position. .. In this case, since the accuracy of the estimated arrival time Tx1 is lowered, the accuracy of the determination time Tx is lowered, so that the judgment accuracy of the deviation from the traveling lane of the steering tracking 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, the amount of change θ1'of the first yaw angle θ1 per unit time with respect to the white line of the steering follow-up target vehicle is θ1'(“ first yaw angle change rate ”or“ yaw angular velocity ””. Is called.) Is acquired. Then, using the first yaw angle change rate θ', it is determined whether or not the steering tracking target vehicle is in a state of deviating from the traveling lane.

However, when the first yaw angle change rate θ'is acquired by calculating from the actual change of the first yaw angle θ1, the acquired first yaw angle change rate θ'is very noisy and the accuracy becomes low. It ends up. Therefore, there is a possibility that the accuracy of determining whether or not the steering follow-up target vehicle deviates from the traveling lane may decrease.

The present invention has been made to address the above-mentioned problems. That is, one of the objects of the present invention is a vehicle driving support device that can reduce the possibility that the determination accuracy of whether or not the steering tracking target vehicle deviates from the traveling lane is lowered (hereinafter, "the present invention". Also referred to as "equipment").

The apparatus of the present invention includes a lane marking unit (17b) that recognizes a lane marking of a traveling lane in which the own vehicle (SV) is traveling, and a lane marking unit (17b).
The division line recognition accuracy determination unit (10) for determining the recognition accuracy of the division line, and the division line recognition accuracy determination unit (10).
A lane width acquisition unit (10) that acquires the lane width (W) of the traveling lane based on the recognized lane markings, and
A traveling locus generation unit (10) that generates a traveling locus (L1) of a steering follow-up target vehicle (TV) specified from among the vehicles in front of the own vehicle.
Vehicle speed acquisition units (17a, 10) that acquire the vehicle speed (v) of the steering follow-up target vehicle, and
Every time a predetermined time (Δtcy) elapses, the past steering follow-up target vehicle when the vertical distance is the same as that of the own vehicle and the horizontal position exists at the position corresponding to the own vehicle at the position on the traveling locus. The first distance (DL1) in the lane width direction between the lane marking (LW) of (TVp) and the past steering follow-up target vehicle, and the first yaw of the past steering follow-up target vehicle with respect to the lane marking. The angle (θ1),
The third distance (DL3) in the lane width direction between the own vehicle and the own vehicle corresponding position acquired based on the recognized lane marking and the traveling locus, and the steering follow-up of the own vehicle. The third yaw angle (θ3) with respect to the traveling locus of the target vehicle, the fourth distance (DL4) in the lane width direction between the own vehicle and the lane marking, and the fourth with respect to the lane marking of the own vehicle. on the basis of the yaw angle (θ4),
The first distance = the fourth distance-the third distance, and
The first yaw angle = the third yaw angle-the fourth yaw angle,
Made to acquired by Equation, a parameter acquisition unit,
Speed of the steering follow-up target vehicle, and the calculating a first standard deviation by substituting lane width to the following equation 1 (.sigma.1), Ru second standard deviation (.sigma. @ 2) der using the following equation 2 Calculate the standard deviation of the error of the first distance (step 945), and calculate the standard deviation of the error of the first yaw angle which is the third standard deviation (σ3) using the following formula 3 (step 950) standard deviation. Calculation unit (10)
When said recognition accuracy the lane mark by the lane mark recognition accuracy determining unit is higher intention determination than the predetermined threshold value, to set the standard deviation of the error of the fourth distance in said formulas 2 to a first value, Set the standard deviation of the error of the fourth yaw angle in the calculation formula 3 to the third value, and set it to the third value.
If the precision of the division line recognized by the lane mark recognition accuracy determining unit is low intention determination than the threshold value, the fourth distance the greater than said first value the standard deviation of the error of the in said formulas 2 The standard deviation calculation configured to set the value to 2 and set the standard deviation of the error of the fourth yaw angle in the calculation formula 3 to a fourth value larger than the third value (step 950). Department and
A parameter estimation unit (10) provided with a Kalman filter (10a).
Each time the predetermined time elapses, the acquired first distance and first yaw angle are input to the Kalman filter as observation values.
Enter the first standard deviation as the process noise and
The second standard deviation and the third standard deviation are input as the observation noise, and the observation noise is input.
According to the principle of the Kalman filter, the first yaw angle change rate (θ1'), which is the amount of change of the first yaw angle per predetermined time, the estimated first distance (DL1f), and the estimated first yaw angle (θ1f). The parameter estimation unit configured to output the calculated first yaw angle change rate, the estimated first distance, and the estimated first yaw angle as output values from the Kalman filter.
The first parameter including the first yaw angle change rate, the estimated first distance, and the estimated first yaw angle, and a second parameter calculated using the first parameter with respect to the lane marking of the steering follow-up target vehicle. A second distance (DL2) in the lane width direction between the steering follow target vehicle and the lane marking using at least one of the parameters including the yaw angle (θ2) and the vehicle speed of the steering follow target vehicle. , The estimated lateral speed (v2) of the steering follow-up target vehicle, and the estimated time (Ta) until the steering follow-up target vehicle reaches the lane marking, and the calculated second distance, estimated lateral speed, And based on at least one of the predicted times
The steering follow-up target vehicle determines whether or not the vehicle is in a deviation state deviating from the traveling lane (step 965).
A traveling control unit (10) that executes steering follow-up control for changing the steering angle of the own vehicle so that the own vehicle travels along a target traveling line set based on the traveling locus.
With
When the travel control unit determines that the steering follow-up target vehicle is in the deviation state (determination of "Yes" in step 965), the travel control unit stops the steering follow-up control (step 910).
When it is determined that the steering follow-up target vehicle is not in the deviation situation (determination of "No" in step 965), the steering follow-up control is executed (step 970).
It is configured as follows.
(Calculation formula 1)
First standard deviation = (4Vxmax ³ / W ² ) x (Δtcy / 3v)
(First standard deviation: standard deviation of the amount of change in the first yaw angle change rate per predetermined time, Vxmax: maximum lateral speed, W: the lane width, Δ ty : the predetermined time, v: the steering follow-up target Vehicle speed)
(Calculation formula 2)
(Standard deviation of error of 1st distance) = ((Standard deviation of error of 3rd distance) ² + (Standard deviation of error of 4th distance) ² ) ^0.5
(Calculation formula 3)
(Standard deviation of error of 1st yaw angle) = ((Standard deviation of error of 3rd yaw angle) ² + (Standard deviation of error of 4th yaw angle) ² ) ^0.5

According to this, the value of the first standard deviation input as the process noise to the Kalman filter is determined according to the vehicle speed of the steering tracking target vehicle and the lane width of the traveling lane. Further, the values of the second standard deviation and the third standard deviation input as the observation noise are determined according to the recognition accuracy of the white line. As a result, the first yaw angle change rate used for calculating the determination parameter can be accurately acquired, and the accuracy of the determination parameter can be improved. As a result, it is possible to reduce the possibility that the accuracy of determining whether or not the steering tracking target vehicle deviates from the traveling lane is reduced.

In the above description, in order to help the understanding of the present invention, the names and / or symbols used in the embodiments are added in parentheses to the configurations 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 name and / or reference numeral.

FIG. 1 is a schematic configuration diagram of a vehicle driving support device according to an embodiment of the present invention. FIG. 2 is a plan view for explaining lane keeping control. FIG. 3A is a plan view for explaining lane keeping control. FIG. 3B is a mathematical formula for explaining the relationship between the coefficient of the cubic function of the traveling locus and the curvature and the like. FIG. 3C is a mathematical formula for explaining the relationship between the coefficient of the cubic function of the traveling locus and the curvature and the like. FIG. 4A 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. 4B 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. 5 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. 6 is a schematic view showing an outline of the operation of the Kalman filter. FIG. 7 is a graph for explaining the derivation method of (calculation formula 1). FIG. 8 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. 9 is a flowchart showing a routine executed by the CPU of the driving support ECU included in the vehicle driving support device according to the embodiment of the present invention.

Hereinafter, the vehicle driving support device (hereinafter, also referred to as “the present embodiment”) according to the 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 designated by the same reference numerals.

(composition)
As shown in FIG. 1, the present implementation device is applied to a vehicle (automobile). The vehicle to which this implementation device is applied may be referred to as "own vehicle" 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 a “DS ECU”.

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

The DSECU is connected to the sensors (including switches) listed below and is adapted to receive detection signals or output signals of those sensors. Each sensor may be connected to an ECU other than the DS ECU. In that case, the DS ECU 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 the operation amount (accelerator opening degree) of the accelerator pedal 11a of the own vehicle, and outputs a signal representing the accelerator pedal operation amount AP.
The brake pedal operation amount sensor 12 detects the operation amount of the brake pedal 12a of the own vehicle and outputs a signal indicating the brake pedal operation amount BP.

The steering angle sensor 14 detects the steering operation angle, which is the rotation angle of the steering wheel SW of the own vehicle, and outputs a signal representing the steering operation angle θ.
The steering torque sensor 15 detects the steering torque applied to the steering shaft US of the own vehicle by operating 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 own vehicle and outputs a signal indicating the vehicle speed SPD.

The surrounding sensor 17 includes a radar sensor 17a, a camera sensor 17b, and a target recognition unit 17c. The surrounding sensor 17 acquires information on at least the road in front of the own vehicle and the three-dimensional object existing on the road. The three-dimensional object represents, for example, a moving object such as a pedestrian, a bicycle or an automobile, and a fixed object such as a utility pole, a tree or a guardrail. Hereinafter, these three-dimensional objects may be referred to as "targets".

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

The peripheral sensor 17 acquires these values based on the xy coordinates defined in advance (see FIG. 2). The x-axis is a coordinate axis that extends along the front-rear direction of the own vehicle SV so as to pass through the center position in the width direction of the front end portion of the own vehicle SV and has the front as a positive value. The y-axis is a coordinate axis that is orthogonal to the x-axis and has a positive value in the left direction of the own vehicle SV. The origin of the x-axis and the origin of the y-axis are the center positions in the width direction of the front end portion of the own vehicle SV. The x-coordinate position of the xy coordinate is called the vertical distance Dfx, and the Y-coordinate position is called the horizontal position Dfy.

The vertical distance Dfx (n) of the target (n) is the front end of the own 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 own vehicle SV). It is a signed distance in the central axis direction (x-axis direction) of the own vehicle SV between them.
The lateral position Dfy (n) of the target (n) is orthogonal to the central axis of the own vehicle SV of the "center position of the target (n) (for example, the center position in the vehicle width direction of the rear end of the vehicle in front)". 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 own vehicle SV. The velocity Vs of the target (n) is the speed of the target (n) in the central axis direction (x-axis direction) of the own vehicle SV.
The relative lateral velocity Vfy (n) of the target (n) is the speed (signed speed) of the center position of the target (n) in the direction (y-axis direction) orthogonal to the central axis of the own vehicle SV. ..

The radar sensor 17a shown in FIG. 1 includes a radar wave transmission / reception unit and a processing unit. The radar wave transmission / reception unit radiates, for example, a radio wave in the millimeter wave band (hereinafter, referred to as "millimeter wave") to a peripheral region of the own vehicle SV including at least the front region of the own vehicle SV, and the radiated millimeter. The reflected wave generated by the wave being reflected by the part of the three-dimensional object (immediately, the reflection point) is received. The radar sensor 17a may be a radar sensor that uses radio waves (radar waves) in a frequency band other than the millimeter wave band.

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

Further, the processing unit of the radar sensor 17a sets the vertical distance Dfx of the target, the orientation θp of the target with respect to the SV of the own vehicle, and the SV of the own vehicle based on the reflection point information of the reflection points belonging to the recognized target. The relative speed Vfx with respect to the target, the vehicle speed v of the target, etc. (hereinafter referred to as "radar sensor detection information") are calculated.

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

The image processing unit determines the presence or absence of a target existing in the photographing area based on the pair of left and right image data captured. If it is determined that the target object exists, the image processing unit, the orientation theta _p of the _target, the vertical distance Dfx of the target, and the relative velocity Vfx like of the vehicle SV and its target (hereinafter, " It is called "camera sensor detection information").

The target recognition unit 17c is connected to the processing unit of the radar sensor 17a and the image processing unit of the camera sensor 17b in a communicable state so as to receive the "radar sensor detection information" and the "camera sensor detection information". It has become. The target recognition unit 17c recognizes the target (n) using at least one of the “radar sensor detection information” and the “camera sensor detection information”, “target ID, vertical distance Dfx (n), horizontal”. "Target information including position Dfy (n), relative velocity Vfx (n), etc." is determined (acquired). The target target recognition unit 17c transmits the determined target information to the DSPE every time a predetermined time elapses.

Further, the image processing unit of the camera sensor 17b sets a lane marking line (a lane marker, hereinafter also simply referred to as a “white line”) such as a white line on the left and right of the road based on a pair of left and right image data. recognize. Then, the image processing unit determines the shape (for example, radius of curvature) of the own vehicle SV traveling lane, which is the lane in which the own vehicle SV is traveling, and the positional relationship between the own vehicle SV traveling lane and the own vehicle SV for a predetermined time. Is calculated and transmitted to the DSECU each time. The positional relationship between the own vehicle SV traveling lane and the own vehicle SV is, for example, the lane between the center position (that is, the center line) of the left white line and the right white line of the own vehicle traveling lane and the center position in the vehicle width direction of the own vehicle SV. It is represented by the distance in the width direction and the angle (that is, the yaw angle) formed by the direction of the center line and the x-axis direction of the own vehicle SV.

Further, the camera sensor 17b calculates information indicating how many meters ahead of the white line in front of the camera sensor 17b (sometimes referred to as "recognition distance information") and outputs the information to the DSPE. It has become. The DSECU determines whether or not the recognition accuracy of the white line is high based on the distance (recognition distance information) at which the camera sensor 17b can recognize the white line.

Information indicating the shape of the own vehicle traveling lane, the positional relationship between the own vehicle traveling lane and the own vehicle in the lane width direction, and the like may be given from the navigation ECU 90.

The operation switch 18 shown in FIG. 1 is a switch operated by the driver of the own vehicle SV. By operating the operation switch 18, the driver can select whether or not to execute the lane keeping control including the steering follow-up control described later. Further, the driver can select whether or not to execute the inter-vehicle distance control (following inter-vehicle distance control) described later by operating the operation switch 18.

The yaw rate sensor 19 detects the yaw rate of the own vehicle SV and outputs the 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. By driving the engine actuator 31, the engine ECU 30 can change the torque generated by the internal combustion engine 32, thereby controlling the driving force of the own vehicle SV and changing the acceleration of the own vehicle SV. 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 a friction brake mechanism 42 provided on the left, right, front and rear wheels. The brake actuator 41 adjusts the hydraulic pressure of the hydraulic oil supplied to the wheel cylinder built in the brake caliper 42b of the friction brake mechanism 42 in response to an instruction from the brake ECU 40, and the brake pads (not shown) are pressed by the hydraulic pressure of the brake disc 42a. Press against to generate friction braking force. Therefore, the brake ECU 40 can control the braking force of the own vehicle SV to change the acceleration (in this case, deceleration) of the own vehicle SV by controlling the brake actuator 41.

The steering ECU 60 is a well-known control device for an electric power steering system, and is connected to a 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, and a steering gear mechanism (not shown)". The steering motor 62 generates torque by the electric power supplied from the motor driver 61, and this torque can generate steering assist torque and steer the left and right steering wheels. That is, the steering motor 62 can change the steering angle (also referred to as "steering angle" or "steering angle") of the own vehicle SV.

The meter ECU 70 is connected to a digital display type meter (not shown). Further, the meter ECU 70 is also connected to the hazard lamp 71 and the stop lamp 72, and the lighting state of these can be changed according to the instruction from the DSP ECU.

The alarm ECU 80 is connected to the buzzer 81 and the display 82. The alarm ECU 80 can sound the buzzer 81 in response to an instruction from the DSECU to alert the driver, and also turn on the alert mark (for example, a warning lamp) on the display 82. can do.

The navigation ECU 90 is connected to a GPS receiver 91 that receives a GPS signal for detecting the current position of the own vehicle SV, a map database 92 that stores map information, and a touch panel display 93. The navigation ECU 90 identifies the current position of the own vehicle SV based on the GPS signal (when the own vehicle SV is traveling on a road having a plurality of lanes, which lane the own vehicle SV is traveling in). Includes information). The navigation ECU 90 performs various arithmetic processes based on the position of the own vehicle SV and the map information stored in the map database 92, and provides route guidance using the display 93 based on the arithmetic processing results.

<Outline of operation>
Next, the outline of the operation of the present implementation device will be described. The DSECU of the present implementation device 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, follow-up inter-vehicle distance control) is the inter-vehicle distance between the vehicle in front and the vehicle SV traveling in front of the vehicle SV in the area in front of the vehicle SV based on the target information. (That is, it is a control that causes the own vehicle SV to follow the preceding vehicle while maintaining the vertical distance Dfx (n) of the vehicle in front of the own vehicle SV at a predetermined target inter-vehicle distance. The following vehicle-to-vehicle distance control itself is well known (see, for example, Japanese Patent Application Laid-Open No. 2014-148293, Japanese Patent Application Laid-Open No. 2006-315491, Japanese Patent No. 4172434, Japanese Patent No. 4929777, etc.). Therefore, it will be briefly described below.

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

First, when the inter-vehicle distance control is required, the DSECU is referred to as a vehicle to be tracked based on the target information of the target (n) acquired by the surrounding sensor 17 (hereinafter referred to as "inter-vehicle distance target vehicle"). To be identified). More specifically, the DSECU determines (identifies) the inter-vehicle distance target vehicle from among other vehicles (that is, vehicles in front) traveling in the front region of the own vehicle SV as follows.

Step 1A: The DSPE acquires "the vehicle speed SPD of the own vehicle SV and the yaw rate Yrt of the own vehicle SV", which is the amount of motion state of the own vehicle SV, from the vehicle speed sensor 16 and the yaw rate sensor 19, respectively.
Step 2A: The DSPE predicts the traveling course of the own vehicle SV in xy coordinates based on the vehicle speed SPD and the yaw rate Yrt.
Step 3A: The DESCU determines the absolute value of the predicted distance in the lane width direction from the traveling course of the own vehicle SV from among other vehicles (that is, vehicles in front) having a positive vertical distance Dfx (n). Another vehicle within the first reference threshold of the above is determined (selected / set) as the inter-vehicle distance target vehicle (a). The first reference threshold value is set so as to decrease as the vertical distance Dfx (n) increases. When there are a plurality of determined other vehicles, the DESCU specifies the other vehicle having the smallest vertical distance Dfx (n) as the inter-vehicle distance target vehicle (a).

When the DESCU specifies the inter-vehicle distance target vehicle (a), the DESCU calculates the target acceleration Gtgt according to any of the following equations (1) and (2). In equations (1) and (2), Vfx (a) is the relative speed of the inter-vehicle distance target vehicle (a), k1 and k2 are predetermined positive gains (coefficients), and ΔD1 is the “inter-vehicle distance target”. It is an inter-vehicle deviation (ΔD1 = Dfx (a) -Dtgt) obtained by subtracting the “target inter-vehicle distance Dtgt” from the “vertical 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 own 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 inter-vehicle distance target vehicle cannot be specified due to the absence of the vehicle in front, the DSECU causes the vehicle speed SPD of the own vehicle SV to match the "target vehicle speed set by using the operation switch 18". In addition, 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 and controls the brake actuator 41 using the brake ECU 40 as necessary so that the acceleration of the own vehicle SV matches the target acceleration Gtgt.

<Lane maintenance control>
When the lane keeping control is required 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 division lane maintenance control and steering follow-up control.

The division lane maintenance control determines the target travel line (target travel route) based on the division lines such as the white line and the yellow line, and the steering angle of the own vehicle SV so that the own vehicle SV travels along the target travel line. It is a control to adjust. The division lane maintenance control is sometimes referred to as "LTC (Lane Trace Control)". In the following, the lane markings will be described as white lines.

The steering follow-up control identifies one of the vehicles in front as the steering follow-up target vehicle TV, and causes the own vehicle SV to travel along the target travel line according to the travel locus of the steering follow-up target vehicle TV. This is a control for adjusting the steering angle (see FIG. 2). Steering follow-up control and division lane maintenance control may also be collectively referred to as "TJA (Traffic Jam Assist)", and may also be referred to as "steering support control" because they are controls that assist the driver's steering operation. .. Hereinafter, description will be added in the order of division lane maintenance control and then steering follow-up control.

<< Section lane maintenance control >>
When at least one of the left white line and the right white line is recognized by the camera sensor 17b in the front direction of the own vehicle SV for a predetermined distance or more, the DSECU has a target traveling line based on at least one of the left white line and the right white line. Set Ld. The DESCU acquires the lane width (that is, the distance between the left white line and the right white line) based on the recognized "positions of the left white line and the right white line" every time a predetermined time elapses, and stores the lane width in the RAM at any time. ing.

More specifically, when both the left white line and the right white line are recognized in the front direction of the own vehicle SV over a predetermined distance or more, the DSECU has the center position of the left white line and the right white line in the lane width direction. The line passing through (that is, the central line) is set as the target traveling line Ld.

On the other hand, in the DSECU, when only one of the left white line and the right white line is recognized in the front direction of the own vehicle SV for a predetermined distance or more, the recognized white line and the left white line are recognized. The position of the unrecognized white line (the other white line) is estimated based on the lane width acquired at the time when both the right white line and the right white line are recognized. Then, the DESCU sets the center line of the recognized white line and the estimated other white line as the target traveling line Ld.

Further, the DSECU is a steering motor so that the lateral position of the own vehicle SV (that is, the position of the own vehicle SV in the lane width direction with respect to the own vehicle travel lane) is maintained near the set target travel line Ld. By applying steering torque to the steering mechanism using 62, the steering angle of the own vehicle SV is changed to support the steering operation of the driver (for example, JP-A-2008-195402, JP-A-2009-). 190464, JP-A-2010-6279, and Patent No. 4349210, etc.). The specific steering control method will be described later.

<< Steering follow-up control >>
When there is no white line recognized in the front direction of the own vehicle SV for more than a predetermined distance, the DSECU is suitable as a steering follow-up target vehicle TV from among other vehicles (front vehicles) traveling in the front region of the own vehicle SV. Select the vehicle ahead. Then, the DESCU generates a traveling locus of the steering follow-up target vehicle TV (hereinafter, also referred to as a "preceding vehicle locus") so that the own vehicle SV travels according to a target traveling line determined based on the preceding vehicle locus. In addition, the steering torque is applied to the steering mechanism to change the steering angle. In this example, the DSPE sets the preceding vehicle locus itself as the target traveling line Ld. However, the DSECU may set a line displaced in the lane width direction by a predetermined distance from the preceding vehicle locus as the target traveling line Ld.

Next, a method of determining the steering follow-up target vehicle TV, a method of generating a preceding vehicle locus, and a method of steering follow-up control will be described.

1. 1. Method for Determining Steering Follow-up Target Vehicle As shown in FIG. 2, the DSECU sets the front vehicle, which is the target (n) for creating the preceding vehicle locus, as the steering follow-up target vehicle TV. The method of setting the steering follow-up target vehicle TV will be described in detail later.

2. Generation of the preceding vehicle locus As shown in FIG. 2, the DSPE generates the traveling locus L1 (that is, the preceding vehicle locus) of the steering follow-up target vehicle TV. More specifically, as shown in FIG. 3A, this traveling locus L1 is represented by the cubic function of the following equation (3) at the above-mentioned xy coordinates at the current position of the own vehicle SV. It is known that the curve is accurately approximated.

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 (x = x0, x0 is an arbitrary value) on the curve).
Cv: When the steering follow-up target vehicle TV was present at the current position (x = 0) of the own vehicle SV (that is, the steering follow-up target vehicle TV was present at the position (x = 0, y = dv)). When) the curvature of the traveling locus L1.
θv: The direction of the traveling locus L1 (tangential direction of the traveling locus L1) and the traveling direction of the own vehicle SV (x-axis) when the steering tracking target vehicle TV is present at the current position (x = 0) of the own vehicle SV. Angle deviation from (+ direction). This angle deviation θv is also called “yaw angle”.
dv: The distance dv between the current position (x = 0, y = 0) of the own vehicle SV and the traveling locus L1 in the y-axis direction (substantially in the lane width direction). This distance dv is also referred to as the "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 as a cubic function f (x) = ax ³ + bx ² + cx + d, and further, the relational expression and the relational expression shown in FIG. 3 (B) and 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. 3 (C), the above equation (3) is derived.

Based on this viewpoint, the DSPE obtains the coefficients of the first to fourth terms (that is, the coefficients a, b, c, and d of the function f (x)) on the right side of the equation (3) as follows. ..

-The DESCU acquires the target information of the steering follow-up target vehicle TV (hereinafter, may be referred to as "target (b)") every time a predetermined measurement time elapses, and obtains the target information. The position coordinate data representing the position (vertical distance Dfx (n) and horizontal position Dfy (n)) of the steering tracking target vehicle TV at the time of acquisition is stored (buffered) in the RAM. In order to reduce the amount of data to be saved as much as possible, the DSPE saves only a certain number of position coordinate data from the latest position coordinate data of the steering tracking target vehicle TV, and sequentially discards the old position coordinate data. You may.

-The DESCU uses the position coordinate data of the steering tracking target vehicle TV stored in the RAM as "the position and traveling direction of the own vehicle SV and the current position and traveling direction of the own vehicle SV" at the time of acquiring the respective position coordinate data. Based on the "difference between" and ", the current position is converted into position coordinate data of xy coordinates with the origin (x = 0, y = 0). The x-coordinate and y-coordinate of the converted position coordinate data (hereinafter, may be referred to as "converted position coordinate") are set as xi and yi, respectively. In this case, (xi, yi) = (x1, y1), (x2, y2), (x3, y3), (x4, y4) shown in FIG. 2 are the steering tracking target vehicles thus acquired. This is an example of the converted position coordinates of the TV.

The DSECU generates the traveling locus L1 of the steering follow-up target vehicle TV by executing the curve fitting process using the changed position coordinates of the steering follow-up target vehicle TV. The curve used in this fitting process is a cubic curve (a curve represented by the above-mentioned cubic function f (x)). The fitting process is performed by the method of least squares.

3. 3. Execution of steering follow-up control The DSECU sets the generated travel locus L1 to the target travel line Ld. Further, the DSECU is necessary for steering follow-up control when the traveling locus L1 is set to the target traveling line Ld based on the coefficient of the cubic function of Eq. (3) and the relational expression shown in FIG. 3 (C). Obtain information (hereinafter, may be referred to as "target track information"). The target track information includes the curvature Cv of the travel locus L1, the yaw angle θv with respect to the travel locus L1, the center distance dv with respect to the travel locus L1, and the like.

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) every time a predetermined time elapses. In the equation (4), Klta1, Klta2 and Klta3 are predetermined control gains. Further, the DSECU controls the steering motor 62 by using the steering ECU 60 so that the actual steering angle θ matches the target steering angle θ *. As described above, the steering control by the steering follow-up control is executed.

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

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) every time a predetermined time elapses. In this case, the DSPE calculates the target steering torque Tr * for obtaining the target yaw rate YRc * based on the target yaw rate YRc * and the actual yaw rate YRt using the look-up table. Then, the DSECU controls the steering motor 62 by using the steering ECU 60 so that the actual steering torque Tra matches the target steering torque Tr *. Steering control by steering follow-up control is also executed by the above. As understood from the above, if the target runway information can be acquired, the DSECU can execute the steering follow-up control without calculating the target running line itself.

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

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

Then, in the equation (4) (or the equation (5)), the DSECU calculates the target steering angle θ * by replacing dv with dL, replacing θv with θL, and replacing Cv with CL. , The steering motor 62 is controlled so that the actual steering angle θ matches the target steering angle θ *. As described above, the steering control by the division lane maintenance control is executed.

When the target traveling line Ld cannot be set based on at least one of the left white line and the right white line and the preceding vehicle locus cannot be generated (including the case where the steering follow-up target vehicle TV cannot be determined). Cancel the execution of lane keeping control. That is, in this case, the DSECU does not perform lane keeping control.

Next, referring to FIGS. 4 (A) and 4 (B), and FIGS. 5 to 8, the “situation in which the steering tracking target vehicle TV deviates from the traveling lane” executed by the DSECU of the present implementation device. A method of determining whether or not the substance is present in the above method will be described.

As shown in FIG. 4A, the DSECU is currently executing steering control (steering follow-up control) so that the own vehicle SV follows the traveling locus L1 of the steering follow-up target vehicle TV.

The DSECU is the steering follow-up target vehicle TV (that is, the past steering follow-up target vehicle TVp) and the white line LW at the time when it was present at the position on the traveling locus L1 corresponding to the position of the own vehicle SV (own vehicle corresponding position). The first parameter (first distance DL1, first yaw angle θ1 (see FIG. 5)) for which the positional relationship with the object is estimated is acquired as follows.

(Acquisition of 3rd distance DL3 and 3rd yaw angle θ3)
First, as shown in FIG. 4A, the DSPE acquires the third distance DL3 in the lane width direction between the own vehicle SV and the own vehicle corresponding position. Further, the DSECU acquires the third yaw angle θ3 with respect to the traveling locus L1 of the steering follow-up target vehicle TV of the own vehicle SV.

The "own vehicle compatible position" is a position where the vertical distance is the same as the vertical distance of the own vehicle SV and the horizontal position is on the traveling locus L1. The horizontal position of the position corresponding to the own vehicle is a value that can be obtained by substituting the vertical distance of the own vehicle SV into the variable x of the above equation (3) representing the traveling locus L1.

(Acquisition of 4th distance DL4 and 4th yaw angle θ4)
Next, as shown in FIG. 4B, the fourth distance DL4 in the lane width direction between the own vehicle SV and the white line LW is acquired. Further, the DSECU acquires the fourth yaw angle θ4 with respect to the white line LW of the own vehicle SV.

(Acquisition of first distance DL1 and first yaw angle θ1)
Then, as shown in FIG. 5, the DSPE acquires the first distance DL1 by subtracting the third distance DL3 from the fourth distance DL4 (first distance DL1 = fourth distance DL4-third distance DL3). do.

Further, the DSECU calculates the difference between the third yaw angle θ3 and the fourth yaw angle θ4 (“first yaw angle θ1” = “third yaw angle θ3” − “fourth yaw angle θ4”). 1 Acquire the yaw angle θ1. From the above, the first parameter (first distance DL1 and first yaw angle θ1) is acquired.

Further, as shown in FIG. 6, the DSECU inputs the first parameter (first distance DL1 and first yaw angle θ1) as an observed value to the Kalman filter 10a provided in the DSECU, thereby estimating as an output value. The 1-distance DL1f, the estimated first yaw angle θ1f, and the first yaw angle change rate θ1'are acquired.

Specifically, the Kalman filter 10a uses Kalman filter processing with σ1 as the observed value (first distance DL1 and first yaw angle θ1), σ1 as the process noise, and σ2 and σ3 as the observed noise as input values. The first distance DL1 (estimated first distance DL1f), the first yaw angle θ1 (estimated first yaw angle θ1f), and the first yaw angle change rate θ1'are calculated as the later output values. ..

As is well known, the Kalman filter 10a (extended Kalman filter) describes a non-linear dynamic system after considering the state equations and observation equations of the system under the influence of noise, and is currently based on these equations. It is an iterative estimation type filter that estimates the current state quantity from the observed value of the above and the estimated value of the past state quantity (for example, JP-A-2007-505377, JP-A-2014-10872, JP-A-2014). Refer to JP-A-102137, JP-A-2014-2103, JP-A-2017-012650, etc.)

The Kalman filter 10a has an observation equation having (DL1, θ1) as an observed value and (σ2, σ3) as an observed noise, and a state equation having (DL1, θ1, θ1') and process noise (σ1) as a state quantity, and the like. Is used to perform a well-known Kalman filter process according to the well-known Kalman filter principle. As a result, the DSPE can acquire the estimated first distance DL1f, the estimated first yaw angle θ1f, and the first yaw angle change rate θ1'.

(Calculation of σ1 to σ3)
The DSECU calculates σ1 to σ3 to be input to the Kalman filter 10a as follows.

(Calculation of σ1)
σ1 is “the standard deviation σΔθ1 ′ of the amount of change Δθ1 ′ of the first yaw angle change rate θ1 ′ per calculation cycle (predetermined time)”. Note that σ1 is also referred to as “first standard deviation” for convenience.

The DESCU calculates by substituting the vehicle speed v, the lane width W, the maximum lateral speed Vmax, and the calculation period ΔTcy of the steering follow-up target vehicle TV into the following (calculation formula 1). An experimentally obtained value is set as the maximum lateral velocity Vxmax. As the maximum lateral speed Vxmax, for example, the maximum lateral speed (fixed value) when it is assumed that the vehicle subject to steering follow-up makes a sudden lane change is set. The maximum lateral speed (value that fluctuates according to the vehicle speed v of the steering tracking target vehicle TV) estimated based on the detected vehicle speed v of the steering tracking target vehicle TV may be set as the maximum lateral speed Vxmax. ..

(Calculation formula 1)
σ1 (= σΔθ1') = (4Vxmax ³ / W ² ) × (Δtcy / 3v)
(Σ1: "Standard deviation of the amount of change in the first yaw angle change rate θ1'per calculation cycle (σΔθ1')", Vxmax: Maximum lateral speed, W: Lane width, Δtcy: Calculation cycle, v: Steering follow-up target vehicle Vehicle speed)

(Calculation formula 1) is a calculation formula derived as follows. It is assumed that the steering follow-up target vehicle TV has made a sudden lane change. At this time, when the maximum lateral speed Vxmax of the steering tracking target vehicle TV and the time from the start to the completion of the lane change are Tf, the relationship between the lateral speed Vx of the steering following target vehicle TV and the time is shown in FIG. It becomes as shown in Graph 1.

During the time period from 0 to 0.5 Tf, the lateral acceleration of the line m1 indicating the lateral speed of the steering follow-up target vehicle TV is constant as shown by the line m2, and becomes Vxmax / 0.5 Tf. In the range of time from 0 to 0.5 Tf, the lateral acceleration change shown on the line m2 is shown on the line m3 having an area representing the velocity of the lateral acceleration change and an area representing the same velocity. Converts to a change in lateral acceleration.

That is, as shown by the line m3, the maximum lateral acceleration at lateral jerk Jx (change amount of lateral acceleration per unit time) in which the lateral acceleration of the steering tracking target vehicle TV is constant during the time period from 0 to 0.25 Tf. After rising to 0.5, it is converted into a lateral acceleration change that decreases to 0 at a constant lateral jerk Jx from 0.25 Tf to 0.5.

The horizontal jerk Jx (hereinafter referred to as "maximum horizontal jerk Jxmax") at this time is (2Vxmax ÷ 0.5Tf) ÷ 0.25T = (16Vxmax / Tf ² ) (= maximum horizontal jerk Jxmax).・ It becomes (1a). The lane width W can be calculated by time-integrating the function shown by the line m1 in the graph 1 in the range from time 0 to Tf. That is, the lane width W = 1/2 × Tf × Vxmax (that is, Tf = 2W / Vxmax). Then, when Tf = 2W / Vxmax is substituted into the above (1a), the maximum lateral jerk Jxmax = 4Vxmax ³ / W ² is obtained.

Here, assuming that the maximum jerk Jxmax is a value with a probability of occurrence of 0.3% that follows a normal distribution with an average of 0, the standard deviation of the jerk is 3σjx = 4Vxmax ³ / W ² . The relational expression (σjx = (v / Δtcy) σΔθ1') between "standard deviation σjx of horizontal jerk" and "standard deviation σΔθ1' of the amount of change of the first yaw angle change rate θ1'per calculation cycle" is made into the above equation. Substituting, σΔθ1'= (4Vxmax ³ / W ² ) × (Δtcy / 3v) is derived. From the above, (calculation formula 1) can be derived, and the standard deviation of the amount of change Δθ1'of the "first yaw angle change rate θ1'" according to the vehicle speed v of the steering tracking target vehicle TV and the lane width W of the traveling lane. σΔθ1'(that is, σ1) ”can be estimated.

(Calculation of σ2 and σ3)
σ2 is the “standard deviation of the error of the first distance DL1”. The DESCU calculates σ2 using the following (calculation formula 2). σ3 is the “standard deviation of the error of the first yaw angle θ1”. The DSPE calculates σ3 using the following (calculation formula 3). Note that σ2 is also referred to as “second standard deviation” for convenience. σ3 is also referred to as the "third standard deviation" for convenience.

(Calculation formula 2)
σ2 = ((“Standard deviation of error of 3rd distance DL3”) ² + (“Standard deviation of error of 4th distance DL4”) ² ) ^0.5
(Calculation formula 3)
σ3 = ((“Standard deviation of error of third yaw angle θ3”) ² + (“Standard deviation of error of fourth yaw angle θ4”) ² ) ^0.5

For the "standard deviation of the error of the third distance DL3" and the "standard deviation of the error of the third yaw angle θ3", for example, experimentally obtained values are appropriately set. Different values are set for the "standard deviation of the fourth distance DL4 error" and the "standard deviation of the error of the fourth yaw angle θ4" according to the accuracy of white line recognition.

Specifically, when the white line recognition accuracy is high, the DSPE sets the "standard deviation of the fourth distance DL4 error" to the first value. When the white line recognition accuracy is low, the DSECU sets the "standard deviation of the fourth distance DL4 error" to a second value larger than the first value. As the first value and the second value, for example, experimentally obtained values are appropriately set.

Further, when the white line recognition accuracy is high, the DSECU sets the “standard deviation of the fourth yaw angle θ4 error” to the third value. When the white line recognition accuracy is low, the DSECU sets the “standard deviation of the fourth yaw angle θ4 error” to a fourth value larger than the third value. As the third value and the fourth value, experimentally obtained values are appropriately set.

(Judgment method)
Further, as shown in FIG. 8, the DESCU has a first parameter (first distance DL1 (DL1f) as an output value after Kalman filter processing, first yaw angle θ1 (θ1f), and first yaw angle change rate θ1'. ), The vehicle speed v of the steering follow-up target vehicle TV, and the first movement time Tx2 (= "inter-vehicle distance / vehicle speed of the steering follow-up target vehicle TV" required for the steering follow-up target vehicle TV to move from the position corresponding to the own vehicle to the current position. Using v "), etc., the second yaw angle θ2, which is the yaw angle with respect to the white line LW of the steering follow-up target vehicle TV, and the steering follow-up target vehicle TV and the white line, according to the following (first formula) to (third formula). The following second parameter (judgment parameter) that estimates the positional relationship with the LW is acquired.

(Judgment parameter)
・ Second distance DL2: Distance in lane width direction between steering tracking target vehicle TV and white line LW ・ Estimated lateral speed v2: Estimated lateral speed of steering tracking target vehicle TV ・ Deviation predicted time Ta: Deviation predicted time Ta = Estimated time until the steering tracking target vehicle TV calculated by 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速度、θ２：第２ヨー角）

(DL2: 2nd distance, DL1: 1st distance, v: Vehicle speed of steering tracking target vehicle, θ1: 1st yaw angle, θ1': 1st yaw angle change rate, Tx2: 1st travel time)

θ2 = θ1 + (θ1'× Tx2) ・ ・ ・ (2nd formula)

(Θ2: 2nd yaw angle, θ1: 1st yaw angle, θ1': 1st yaw angle change rate, Tx2: 1st movement time)

v2 = v × θ2 ... (3rd formula)
(V2: Estimated lateral speed, v: Speed of steering tracking target vehicle, θ2: Second yaw angle)

The DESCU determines the deviation state from the traveling lane of the steering tracking target vehicle TV by using the acquired determination parameters (second distance DL2, estimated lateral speed v2, and deviation prediction time Ta).

Specifically, the DSECU first determines whether or not the steering follow-up target vehicle TV is in a deviation state deviating from the traveling lane by using the determination parameter.

When at least one of the following deviation status determination conditions 1 to 3 is satisfied, the DSPE determines that the steering follow-up target vehicle TV is in the deviation status.
Deviation situation determination condition 1: The second distance DL2 is equal to or less than the first threshold distance Dth1.
Deviation situation determination condition 2: The estimated lateral velocity v2 is equal to or higher than the first threshold lateral velocity vth1.
Deviation situation determination condition 3: The deviation prediction time Ta (= DL2 / v2) is equal to or less than the first threshold time Tth1.

When the steering follow-up target vehicle TV is in a deviation state, the DESCU cancels the steering follow-up control. When the steering follow-up target vehicle TV is not in a deviation state, the DSECU executes steering follow-up control.

<Specific operation>
Next, the specific operation of the CPU of the DSECU (sometimes referred to simply as "CPU") will be described. The CPU executes the steering follow-up control routine shown by the flowchart of FIG. 9 every time a predetermined time (calculation cycle Δtcy) elapses. The CPU executes inter-vehicle distance control (ACC) by a routine (not shown). The CPU executes the routine shown in FIG. 9 only when the inter-vehicle distance control is executed.

Therefore, when the inter-vehicle distance control is executed, when the predetermined timing is reached, the CPU starts the process from step 900 in FIG. 9 and proceeds to step 905, and whether or not the execution condition of the steering follow-up control is satisfied. Is determined.

The execution condition of the steering follow-up control is satisfied, for example, when all of the conditions A1 to A3 described below are satisfied.
Condition A1: It is selected to execute the lane keeping control by operating the operation switch 18.
Condition A2: The vehicle speed SPD of the own vehicle SV is equal to or greater than a predetermined lower limit vehicle speed and equal to or less than a predetermined upper limit vehicle speed.
Condition A3: The target traveling line Ld based on "at least one of the left white line and the right white line" recognized by the camera sensor 17b cannot be set.

If the execution condition of the steering follow-up control is not satisfied, the CPU determines "No" in step 905, proceeds to step 910, and cancels (stops) the steering follow-up control. After that, the CPU proceeds to step 995 and temporarily ends this routine.

On the other hand, when the execution condition of the steering follow-up control is satisfied, the CPU determines "Yes" in step 905 and proceeds to step 915 to set the steering follow-up target vehicle TV for which the traveling locus L1 is to be generated. Identify. Specifically, the CPU acquires the vehicle speed of the own vehicle SV from the vehicle speed sensor 16 and acquires the yaw rate of the own vehicle SV from the yaw rate sensor 19. The CPU predicts the traveling course of the own vehicle SV from the acquired vehicle speed and yaw rate. Next, the target closest to the vehicle in front that is closest to the predicted "traveling course of the own vehicle SV" is selected as the "steering follow-up target vehicle TV that is the target of generating the traveling locus L1".

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

After that, the CPU proceeds to step 920 and determines whether or not the traveling locus L1 can be generated. Specifically, when the steering follow-up target vehicle TV cannot be specified, or when the steering follow-up target vehicle TV can be specified, the time-series data of the target information about the steering follow-up target vehicle TV is the traveling locus. If it is not enough to generate L1, the CPU determines that the traveling locus L1 cannot be generated. If not, the CPU determines that the travel locus L1 has been generated.

When the traveling locus L1 can be generated, the CPU determines "Yes" in step 920, proceeds to step 925, and a white line (white line) by the camera sensor 17b based on the "recognition distance information" sent from the camera sensor 17b. It is determined whether or not the left white line and the right white line) can be recognized within the range of the first predetermined distance or more and less than the second predetermined distance. In other words, the CPU determines whether or not the white line can be recognized in the vicinity by the camera sensor 17b. The first predetermined distance is set to be smaller than the second predetermined distance.

When the camera sensor 17b can recognize the white line in the range of the first predetermined distance or more and less than the second predetermined distance, the CPU determines "Yes" in step 925 and proceeds to step 930, and steps 930 to 930 described below. After performing the processing of 960 in order, the process proceeds to step 965.

Step 930: The CPU acquires the third distance DL3 in the lane width direction between the own vehicle SV and the own vehicle corresponding position. Further, the CPU acquires the third yaw angle θ3 with respect to the traveling locus L1 of the steering follow-up target vehicle TV of the own vehicle SV.
Step 935: The CPU acquires the fourth distance DL4 in the lane width direction between the own vehicle SV and the white line LW. Further, the CPU acquires the fourth yaw angle θ4 with respect to the white line LW of the own vehicle SV.
Step 940: The CPU acquires the first distance DL1 by subtracting the third distance DL3 from the fourth distance DL4 (first distance DL1 = fourth distance DL4-third distance DL3).
The CPU acquires the first yaw angle θ1 by calculating the difference between the third yaw angle θ3 and the fourth yaw angle θ4 (first yaw angle θ1 = third yaw angle θ3-fourth yaw angle θ4). ..

Step 945: The CPU calculates (estimates) σ1 using (calculation formula 1) as described above.
Step 950: The CPU calculates (estimates) σ2 using (Calculation Formula 2) as described above. At this time, if the white line recognition accuracy is high, the CPU sets the "standard deviation of the fourth distance DL4 error" of (calculation formula 2) to the first value. When the white line recognition accuracy is low, the CPU sets the "standard deviation of the fourth distance DL4 error" of (calculation formula 2) to a second value larger than the first value.
The CPU calculates σ3 using (Calculation Formula 3) as described above. At this time, if the white line recognition accuracy is high, the CPU sets the “standard deviation of the fourth yaw angle θ4 error” of (calculation formula 3) to the third value. When the white line recognition accuracy is low, the CPU sets the "standard deviation of the fourth yaw angle θ4 error" of (calculation formula 3) to a fourth value larger than the third value.

Step 955: The CPU acquires the estimated first distance DL1f, the estimated first yaw angle θ1f, and the first yaw angle change rate θ1'using the Kalman filter 10a as described above.

Step 960: The CPU uses the estimated first distance DL1f, the estimated first yaw angle θ1f and the first yaw angle change rate θ1'(first parameter), and the vehicle speed v and the first travel time Tx2 as described above. The determination parameters (second distance DL2, estimated lateral velocity v2, and deviation prediction time Ta) are calculated.

When the CPU proceeds to step 965, it determines whether or not the steering follow-up target vehicle TV is in a deviation state based on the determination parameter. When at least one of the above-mentioned deviation situation determination conditions 1 to 3 is satisfied, the CPU determines that the steering follow-up target vehicle TV is in the deviation state.

If the steering follow-up target vehicle TV is not in a deviation state, the CPU determines "No" in step 965 and proceeds to step 970, and sets the travel locus L1 generated based on the steering follow-up target vehicle in step 915 as the target travel line. It is set to Ld, and the steering angle of the own vehicle SV is controlled so that the own vehicle SV travels along the target traveling line Ld (steering control is performed). That is, the CPU executes steering follow-up control. After that, the CPU proceeds to step 995 and temporarily ends this routine.

When the steering follow-up target vehicle TV is in a deviation state, the CPU determines "Yes" in step 965, proceeds to step 910, and cancels (stops) the steering follow-up control. After that, the CPU proceeds to step 995 and temporarily ends this routine.

The present implementation device described above has the following effects. That is, the value of σ1 input as process noise to the Kalman filter 10a is determined according to the vehicle speed v of the steering tracking target vehicle TV and the lane width W of the traveling lane. Further, the values of σ2 and σ3 input as observation noise are determined according to the recognition accuracy of the white line. As a result, the present implementation device can accurately acquire the first yaw angle change rate θ1'used for calculating the determination parameter, and can improve the accuracy of the determination parameter. As a result, it is possible to reduce the possibility that the accuracy of determining whether or not the steering follow-up target vehicle deviates from the traveling lane is reduced.

<Modification example>
Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications based on the technical idea of the present invention are possible.

For example, the present implementation device is configured to execute the lane keeping control only while the following inter-vehicle distance control is being executed, but is configured to execute the lane keeping control even when the following inter-vehicle distance control is not being executed. You may.

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

For example, in the present embodiment, the method of generating the traveling locus is not limited to the above-mentioned example, and various known methods can be adopted. That is, any method may be used as long as it can create a curve that approximates the traveling locus (preceding vehicle locus) of the steering tracking target vehicle, and for example, a traveling locus may be generated by using a Kalman filter.

Specifically, in step 915, the CPU may generate a traveling locus using a Kalman filter. When the position information of the own vehicle is input to the Kalman filter provided in the driving support ECU 10, the Kalman filter indicates the curvature Cv of the traveling locus L1 of the steering following vehicle at the current position of the own vehicle SV, the curvature change rate Cv'of the traveling locus L1, and the traveling locus L1. The yaw angle θv of the own vehicle SV and the distance dv between the traveling locus L1 and the current position of the own vehicle SV are output. The CPU can obtain the coefficients a, b, c and d of the cubic function f (x) by using the relationship between the coefficient of the cubic function shown in FIG. 3C and the curvature, the yaw angle and the like. can.

10 ... Driving support ECU, 16 ... Vehicle speed sensor, 17 ... Surrounding sensor, 17a ... Radar sensor, 17b ... Camera sensor, 17c ... Target recognition unit, 18 ... Operation switch, 19 ... Yaw rate sensor, 60 ... Steering ECU, 61 ... Motor driver, 62 ... Steering motor, 80 ... Alarm ECU, 81 ... Buzzer, 82 ... Display, SV ... Own vehicle, TV ... Steering follow-up target vehicle, TVp ... Past steering follow-up target vehicle

Claims (1)

A lane marking unit that recognizes the lane marking of the driving lane in which the vehicle is traveling, and a lane marking unit.
A lane marking accuracy determination unit that determines the lane marking accuracy
A lane width acquisition unit that acquires the lane width of the traveling lane based on the recognized lane markings, and
A traveling locus generation unit that generates a traveling locus of a steering follow-up target vehicle specified from among the vehicles in front of the own vehicle, and a traveling locus generator.
A vehicle speed acquisition unit that acquires the vehicle speed of the steering tracking target vehicle, and a vehicle speed acquisition unit.
Each time a predetermined time elapses, the section of the past steering follow-up target vehicle when the vertical distance is the same as that of the own vehicle and the horizontal position exists at the position corresponding to the own vehicle at the position on the traveling locus. The first distance in the lane width direction between the line and the past steering follow-up target vehicle and the first yaw angle of the past steering follow-up target vehicle with respect to the lane marking.
The recognized lane marking, the third distance in the lane width direction between the own vehicle and the own vehicle corresponding position acquired based on the traveling locus, and the steering follow-up target vehicle of the own vehicle. Based on the third yaw angle with respect to the traveling locus, the fourth distance in the lane width direction between the own vehicle and the lane marking, and the fourth yaw angle with respect to the lane marking of the own vehicle .
The first distance = the fourth distance-the third distance, and
The first yaw angle = the third yaw angle-the fourth yaw angle,
Made to acquired by Equation, a parameter acquisition unit,
The steering follow-up target vehicle speed, and the lane width to calculate a first standard deviation by substituting the following equation 1, the error of the first distance Ru second standard deviation der using the following equation 2 A standard deviation calculation unit that calculates the standard deviation and calculates the standard deviation of the error of the first yaw angle, which is the third standard deviation, using the following formula 3.
When said recognition accuracy the lane mark by the lane mark recognition accuracy determining unit is higher intention determination than the predetermined threshold value, to set the standard deviation of the error of the fourth distance in said formulas 2 to a first value, Set the standard deviation of the error of the fourth yaw angle in the calculation formula 3 to the third value, and set it to the third value.
The partition line recognition accuracy determining when said accuracy of a lane mark recognition is low intention determination than the threshold value by the unit, the calculation formula of the fourth distance error standard deviation of 2 the first value is greater than the second And the standard deviation calculation unit configured to set the standard deviation of the error of the fourth yaw angle in the calculation formula 3 to a fourth value larger than the third value.
It is a parameter estimation unit equipped with a Kalman filter.
Each time the predetermined time elapses, the acquired first distance and first yaw angle are input to the Kalman filter as observation values.
Enter the first standard deviation as the process noise and
The second standard deviation and the third standard deviation are input as the observation noise, and the observation noise is input.
According to the principle of the Kalman filter, the first yaw angle change rate, the estimated first distance, and the estimated first yaw angle, which are the amounts of change of the first yaw angle per predetermined time, are calculated, and the calculated first yaw angle is calculated. The parameter estimation unit configured to output the angle change rate, the estimated first distance, and the estimated first yaw angle as output values from the Kalman filter.
The first parameter including the first yaw angle change rate, the estimated first distance, and the estimated first yaw angle, and a second parameter calculated using the first parameter with respect to the lane marking of the steering follow-up target vehicle. Using at least one of the parameters including the yaw angle and the vehicle speed of the steering follow target vehicle, a second distance in the lane width direction between the steering follow target vehicle and the lane marking, the steering follow target vehicle The estimated lateral speed and the estimated time until the steering follow-up target vehicle reaches the lane marking are calculated, and based on at least one of the calculated second distance, the estimated lateral speed, and the estimated time.
A traveling lane deviation status determination unit that determines whether or not the steering follow-up target vehicle is in a deviation status that deviates from the traveling lane.
A travel control unit that executes steering follow-up control that changes the steering angle of the own vehicle so that the own vehicle travels along a target travel line set based on the travel locus.
With
When the travel control unit determines that the steering follow-up target vehicle is in the deviation state, the travel control unit stops the steering follow-up control.
When it is determined that the steering follow-up target vehicle is not in the deviation situation, the steering follow-up control is executed.
Vehicle driving support device configured to.
(Calculation formula 1)
First standard deviation = (4Vxmax ³ / W ² ) x (Δtcy / 3v)
(First standard deviation: standard deviation of the amount of change in the first yaw angle change rate per predetermined time, Vxmax: maximum lateral speed, W: the lane width, Δ ty : the predetermined time, v: the steering follow-up target Vehicle speed)
(Calculation formula 2)
(Standard deviation of error of 1st distance) = ((Standard deviation of error of 3rd distance) ² + (Standard deviation of error of 4th distance) ² ) ^0.5
(Calculation formula 3)
(Standard deviation of error of 1st yaw angle) = ((Standard deviation of error of 3rd yaw angle) ² + (Standard deviation of error of 4th yaw angle) ² ) ^0.5

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