JP2019051808A - Drive assist apparatus - Google Patents

Abstract

To accurately set a travel lane from a section line.SOLUTION: A drive assist apparatus includes: section line recognition means for estimating a center line that is a central position between section lines of a road a vehicle itself is traveling on; travel locus generation means for generating a travel locus of a preceding vehicle; and lane keep control means for assisting steering control of the vehicle itself so as to travel along a target travel line. In a case where reliability of the center line is determined to be low when lane keep control is executed, the lane keep control means lowers response of the lane keep control as compared to the case of the reliability of the center line being not low, until a position and orientation of the vehicle itself becomes consistent with the target travel line.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a driving support device that executes lane keeping control for supporting traveling near the center of a lane of a vehicle (own vehicle) by using at least a lane marking of a road.

  One of the conventionally known driving assistance devices (hereinafter referred to as “conventional device”) uses at least lane markings (white line, yellow line, etc.) on the road, Lane maintenance control is performed to perform steering control so that the vehicle travels at an appropriate position in the “specified travel lane (travel lane)” (see, for example, Patent Document 1).

JP, 2006-218649, A

  When executing the lane keeping control, the conventional device detects white line candidates existing on the left and right sides of the road, and calculates the likelihood (probability of being a white line) for each of the white line candidates. The conventional apparatus determines a white line based on the above-described likelihood, and sets a line connecting the center positions between the determined white lines as the target travel line.

  However, when the lane keeping control is executed using the recognition result of the white line, the following problem may occur. For example, when the white line is thin, the likelihood calculated for the curb extending along the white line is larger than the likelihood calculated for the thin white line. Therefore, the conventional apparatus erroneously recognizes the curb as a white line, and sets a line connecting the center position between the one white line and the curb as a target travel line. And a conventional apparatus performs steering control so that the own vehicle may approach the curb side compared with the center position between the left and right white lines. As a result, when the white line is erroneously recognized, there has been a problem that the position and orientation of the host vehicle suddenly change toward the curb.

  The present invention has been made to solve the above problems. That is, one of the objects of the present invention is to reduce the possibility that the position and direction of the host vehicle suddenly change due to misrecognition of a lane marking that divides a lane including a white line and a yellow line. It is to provide a driving support device.

The driving assistance device of the present invention (hereinafter sometimes referred to as “the present invention device”)
Lane marking recognition means (10, 10b, 16) for recognizing the lane marking of the road on which the host vehicle is traveling and estimating a central line that connects the central positions between the lane markings;
Traveling locus creating means (10, 10c, 16) for creating a traveling locus of a preceding vehicle traveling in front of the host vehicle;
Lane keeping control means (10, 10d, 40) for executing lane keeping control for changing the steering angle of the host vehicle so that the host vehicle travels along the target travel line set based on the center line;
Is provided.

Further, the lane keeping control means includes
When performing the lane keeping control,
A first distance change amount (| dL2-dL1 |) that is a magnitude of a change amount in a first predetermined time of the distance in the road width direction between the center line and the host vehicle, and the direction of the center line and the vehicle At least one of a first angle change amount (| θL2−θL1 |) that is a magnitude of a change amount in a second predetermined time of a deviation angle from the traveling direction of the vehicle;
A second distance change amount (| dv2-dv1 |) that is a magnitude of a change amount of the distance in the road width direction between the travel locus and the host vehicle in the first predetermined time and a direction of the travel locus; At least one of a second angle change amount (| θv2-θv1 |) that is a magnitude of a change amount in the second predetermined time of a deviation angle from the traveling direction of the host vehicle;
Based on whether the reliability of the center line is low (steps 835 and 840),
When it is determined that the reliability of the center line is low, the lane until the position and orientation of the host vehicle is matched with the target travel line as compared with the case where it is determined that the reliability of the center line is not low. The maintenance control response is reduced (step 845).

  The lane keeping control means included in the device of the present invention includes at least one of a first distance change amount (| dL2-dL1 |) and a first angle change amount (| θL2-θL1 |), and a second distance change amount (| dv2- The reliability of the central line is determined based on at least one of dv1 |) and the second angle change amount (| θv2-θv1 |). Furthermore, when the lane keeping control means determines that the reliability of the center line is low, the lane keeping control means matches the position and direction of the host vehicle with the target travel line as compared to the case where the reliability of the center line is determined not to be low. The responsiveness (steering control amount) of the lane keeping control is reduced. Thereby, when the reliability of the center line is low, that is, when there is a possibility that erroneous recognition of the lane marking has occurred, it is possible to suppress a sudden change in the position and orientation of the host vehicle.

  In the above description, in order to help understanding of the present invention, names and / or symbols used in the embodiment are attached to the configuration of the invention corresponding to the embodiment described later in parentheses. However, each component of the present invention is not limited to the embodiment defined by the reference numerals.

It is a schematic block diagram of the driving assistance device concerning this embodiment of the present invention. It is a top view for demonstrating lane maintenance control using the target travel line determined based on a white line. It is a top view for demonstrating lane maintenance control using the target travel line determined based on the travel locus (preceding vehicle locus) of a preceding vehicle. (A) is a top view for demonstrating in detail the lane maintenance control shown in FIG. 3, (B) is for demonstrating the relationship between the coefficient of the cubic function of a preceding vehicle locus, a curvature, a curvature radius, etc. (C) is an equation for explaining the relationship between the coefficient of the cubic function of the preceding vehicle trajectory, the curvature, the yaw angle, and the like. It is a figure for demonstrating the target driving | running line produced based on the center line of a driving | running lane, and a preceding vehicle locus. (A) is a plan view showing the relationship between the estimated center line of the traveling lane and the position of the host vehicle at time t = t1, and (B) is the estimated traveling lane at time t = t2. It is a top view which shows the relationship between this center line and the position of the own vehicle. (A) is a plan view showing the distance between the own vehicle and the preceding vehicle locus at time t = t1, and (B) shows the distance between the own vehicle and the preceding vehicle locus at time t = t2. FIG. It is the flowchart which showed the routine which driving assistance ECU which concerns on this embodiment of this invention performs.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The attached drawings show specific embodiments in accordance with the principle of the present invention, but these are examples for understanding the present invention and should not be used to interpret the present invention in a limited manner.

  As shown in FIG. 1, the driving support apparatus according to the embodiment of the present invention (hereinafter, may be referred to as “the present implementation apparatus”) is applied to a vehicle (automobile). A vehicle to which the present embodiment is applied may be referred to as “own vehicle” in order to distinguish it from other vehicles. The present embodiment includes a driving assistance ECU 10, an engine ECU 20, a brake ECU 30, and a steering ECU 40.

  These ECUs are electric control units (Electric Control Units) each 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). In this specification, the microcomputer includes a CPU, a ROM, a RAM, a nonvolatile memory, an interface I / F, and the like. The CPU implements various functions by executing instructions (programs, routines) stored in the ROM.

  The driving assistance ECU 10 is connected to sensors (including switches) listed below, and receives detection signals or output signals from these sensors. Each sensor may be connected to an ECU other than the driving support ECU 10. In that case, the driving assistance ECU 10 receives a detection signal or an output signal of the sensor via the CAN from the ECU to which the sensor is connected.

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

The steering angle sensor 13 detects the steering angle of the host vehicle and outputs a signal representing the steering angle θ. The driving assistance ECU 10 calculates a steering angular velocity (= dθ / dt) that is a change amount per unit time of the steering angle θ received from the steering angle sensor 13.
The steering torque sensor 14 detects the steering torque applied to the steering shaft US of the host vehicle by operating the steering handle SW, and outputs a signal representing the steering torque Tra.
The vehicle speed sensor 15 detects the traveling speed (vehicle speed) of the host vehicle and outputs a signal representing the vehicle speed SPD.

  The ambient sensor 16 is configured to acquire information on at least a road ahead of the host vehicle and a three-dimensional object existing on the road. The three-dimensional object represents, for example, a moving object such as a pedestrian, a bicycle, and a car, and a fixed object such as a utility pole, a tree, and a guardrail. Hereinafter, these three-dimensional objects may be referred to as “targets”. The ambient sensor 16 includes a radar sensor 16a and a camera sensor 16b.

  The radar sensor 16a radiates, for example, a millimeter-wave band radio wave (hereinafter referred to as “millimeter wave”) to at least a peripheral region of the host vehicle including the front region of the host vehicle, and targets existing within the radiation range. The millimeter wave reflected by (i.e., the reflected wave) is received. Further, the radar sensor 16a calculates the presence / absence of the target and the relative relationship between the host vehicle and the target (that is, the distance between the host vehicle and the target, the relative speed between the host vehicle and the target, etc.). It is designed to output.

  More specifically, the radar sensor 16a includes a millimeter wave transmission / reception unit and a processing unit. The processing unit has a phase difference between the millimeter wave transmitted from the millimeter wave transmitting / receiving unit and the reflected wave received by the millimeter wave transmitting / receiving unit, the attenuation level of the reflected wave, and the time from when the millimeter wave is transmitted until the reflected wave is received. Based on the above, a parameter indicating the relative relationship between the host vehicle and the target is acquired every elapse of a predetermined time. This parameter includes an inter-vehicle distance (vertical distance) Dfx (n), a relative speed Vfx (n), a lateral distance Dfy (n), a relative lateral speed Vfy (n), and the like for each detected target (n).

The inter-vehicle distance Dfx (n) is a distance along the central axis (a central axis extending in the front-rear direction) of the host vehicle between the host vehicle and the target (n) (for example, a preceding vehicle).
The relative speed Vfx (n) is a difference (= Vs−Vj) between the speed Vs of the target (n) (for example, the preceding vehicle) and the speed Vj of the host vehicle. The speed Vs of the target (n) is the speed of the target (n) in the traveling direction of the host vehicle.
The lateral distance Dfy (n) is a distance from the central axis in the direction orthogonal to the central axis of the host vehicle of the “center position of the target (n) (for example, the vehicle width center position of the preceding vehicle)”. The lateral distance Dfy (n) is also referred to as “lateral position”.
The relative lateral speed Vfy (n) is a speed in a direction orthogonal to the center axis of the host vehicle at the center position of the target (n) (for example, the vehicle width center position of the preceding vehicle).

  The camera sensor 16b includes a stereo camera and an image processing unit, captures a landscape of the left area and the right area in front of the vehicle, and acquires a pair of left and right image data. The camera sensor 16b is configured to calculate and output the presence / absence of a target and the relative relationship between the host vehicle and the target based on the captured pair of left and right image data. In this case, the driving support ECU 10 combines the relative relationship between the host vehicle and the target obtained by the radar sensor 16a and the relative relationship between the host vehicle and the target obtained by the camera sensor 16b. The relative relationship between the host vehicle and the target (a parameter representing the relative relationship) is determined.

  Furthermore, the camera sensor 16b recognizes the left and right lane markings on the road based on the captured pair of left and right image data, and determines the shape of the road and the positional relationship between the road and the vehicle (for example, driving) The distance from the left end or the right end of the lane to the center position in the vehicle width direction of the host vehicle is calculated and output. In addition, although a division line contains a white line, a yellow line, etc., below, the example of a white line is demonstrated as an example.

  Information about the target acquired by the surrounding sensor 16 (including a parameter indicating a relative relationship) is referred to as “target information”. The surrounding sensor 16 repeatedly transmits the target information to the driving support ECU 10 every time a predetermined time elapses. Note that the ambient sensor 16 does not necessarily include both the radar sensor and the camera sensor, and may include, for example, only the radar sensor or only the camera sensor.

  The operation switch 17 is a switch operated by the driver. The driver can select whether or not to execute the lane keeping control described later by operating the operation switch 17. Furthermore, the driver can select whether or not to execute the following inter-vehicle distance control described later by operating the operation switch 17.

  The yaw rate sensor 18 detects the yaw rate of the host vehicle and outputs an actual yaw rate YRt.

  The engine ECU 20 is connected to the engine actuator 21. The engine actuator 21 includes a throttle valve actuator that changes the opening of the throttle valve of the internal combustion engine 22. The engine ECU 20 can change the torque generated by the internal combustion engine 22 by driving the engine actuator 21. Torque generated by the internal combustion engine 22 is transmitted to drive wheels (not shown) via a transmission (not shown). Therefore, the engine ECU 20 can control the driving force of the host vehicle and change the acceleration state (acceleration) by controlling the engine actuator 21. When the host vehicle is a hybrid vehicle, the engine ECU 20 can control the driving force of the host vehicle generated by either or both of the “internal combustion engine and the electric motor” as the vehicle drive source. Further, when the host vehicle is an electric vehicle, the engine ECU 20 can control the driving force of the host vehicle generated by an electric motor as a vehicle drive source.

  The brake ECU 30 is connected to the brake actuator 31. The brake actuator 31 is provided in a hydraulic circuit between a master cylinder (not shown) that pressurizes hydraulic oil by the depression force of the brake pedal 12a and a friction brake mechanism 32 provided on the left and right front and rear wheels. The brake actuator 31 adjusts the hydraulic pressure supplied to the wheel cylinder built in the brake caliper 32 b of the friction brake mechanism 32 in accordance with an instruction from the brake ECU 30. When the wheel cylinder is actuated by the hydraulic pressure, the brake pad is pressed against the brake disc 32a and a friction braking force is generated. Therefore, the brake ECU 30 can change the acceleration state (deceleration, that is, negative acceleration) by controlling the braking force of the host vehicle by controlling the brake actuator 31.

  The steering ECU 40 is a known control device for an electric power steering system, and is connected to a motor driver 41. The motor driver 41 is connected to the steering motor 42. The steering motor 42 is incorporated in a “steering mechanism including a steering handle, a steering shaft connected to the steering handle, a steering gear mechanism, and the like” of a vehicle (not shown). The steering motor 42 generates torque by the electric power supplied from the motor driver 41, and can apply steering assist torque or steer the left and right steering wheels by this torque. That is, the steering motor 42 can change the steering angle of the host vehicle.

  Next, the outline | summary of the action | operation of this implementation apparatus is demonstrated. The driving assistance ECU 10 can execute “following inter-vehicle distance control” and “lane keeping control”.

<Following distance control (ACC: Adaptive Cruise Control)>
Follow-up inter-vehicle distance control is a control based on target information that keeps the host vehicle following the preceding vehicle while maintaining a predetermined distance between the host vehicle and the preceding vehicle traveling immediately before the host vehicle. is there. The following inter-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, and Japanese Patent No. 4929777). Accordingly, a brief description will be given below.

  The driving assistance ECU 10 executes the following inter-vehicle distance control when the following inter-vehicle distance control is requested by the operation of the operation switch 17.

  More specifically, the driving assistance ECU 10 selects the tracking target vehicle based on the target information acquired by the surrounding sensor 16 when the tracking inter-vehicle distance control is required. For example, the driving assistance ECU 10 determines that the relative position of the target (n) specified from the detected lateral distance Dfy (n) and inter-vehicle distance Dfx (n) of the target (n) increases as the inter-vehicle distance increases. It is determined whether or not the vehicle is present in a predetermined tracking target vehicle area so that the absolute value of is small. Then, when the relative position of the target (n) exists in the tracking target vehicle area for a predetermined time or more, the driving support ECU 10 selects the target (n) as the tracking target vehicle.

  Further, the driving assistance ECU 10 calculates the target acceleration Gtgt according to either of the following formulas (1) and (2). In the equations (1) and (2), Vfx (a) is the relative speed of the vehicle to be followed (a), k1 and k2 are predetermined positive gains (coefficients), and ΔD1 is “the vehicle to be followed ( The inter-vehicle deviation (= Dfx (a) −Dtgt) obtained by subtracting the “target inter-vehicle distance Dtgt” from the inter-vehicle distance Dfx (a) ”of 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 17 by the vehicle speed SPD of the host vehicle 100 (that is, Dtgt = Ttgt · SPD).

When the value (k1 · ΔD1 + k2 · Vfx (a)) is positive or “0”, the driving assistance ECU 10 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 driving assistance ECU 10 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 does not exist in the tracking target vehicle area, the driving assistance ECU 10 sets the target speed and the vehicle speed SPD so that the vehicle speed SPD of the host vehicle matches the “target speed set according to the target inter-vehicle time Ttgt”. Based on this, the target acceleration Gtgt is determined.

  The driving assistance ECU 10 controls the engine actuator 21 using the engine ECU 20 and the brake actuator 31 using the brake ECU 30 as necessary so that the acceleration of the vehicle matches the target acceleration Gtgt. As described above, the driving assistance ECU 10 has the “ACC control unit 10a that executes the following inter-vehicle distance control (ACC)” that is functionally realized by the CPU.

<Lane maintenance control>
The driving support ECU 10 executes the lane keeping control when the lane keeping control is requested by the operation of the operation switch 17 during the execution of the following inter-vehicle distance control.

  In the lane keeping control called LTC (Lane Trace Control), the driving assistance ECU 10 utilizes the white line or the traveling locus of the preceding vehicle (sometimes called the “preceding vehicle locus”), or both of them. To set a target travel line (target travel path). The driving assistance ECU 10 maintains the lateral position of the host vehicle (that is, the position of the host vehicle in the vehicle width direction with respect to the road) near the target travel line in the “lane in which the host vehicle is traveling (travel lane)”. As described above, the steering torque is applied to the steering mechanism to change the steering angle (steering angle) of the host vehicle, thereby assisting the driver's steering operation (for example, Japanese Unexamined Patent Application Publication Nos. 2008-195402 and 2009). -190464, JP 2010-6279, and Japanese Patent No. 4349210). The lane keeping control may also be referred to as “TJA (Traffic Jam Assis)”.

  Hereinafter, the lane keeping control using the target travel line determined based on the white line will be described. As described below, the driving assistance ECU 10 acquires target lane information necessary for lane keeping control based on the white line recognized by the camera sensor 16b.

  Specifically, as shown in FIG. 2, the driving assistance ECU 10 is driving the host vehicle 100 based on information transmitted from the surrounding sensor 16 (information that the camera sensor 16 b can recognize). Recognize the “left white line LL and right white line LR” of the traveling lane, and acquire their position information. The driving assistance ECU 10 estimates a line connecting the center position between the acquired pair of white lines as a “travel lane center line” LM. As described above, the driving assistance ECU 10 has a “partition line recognition unit (partition line recognition unit) 10 b that recognizes a lane line and estimates a center line of a traveling lane” that is functionally realized by the CPU. .

  Further, the driving support ECU 10 determines the position and direction of the host vehicle 100 in the travel lane defined by the curve radius R and the curvature CL (= 1 / R) of the center line LM of the travel lane, and the left white line LL and the right white line LR. And calculate. Then, as shown in FIG. 2, the driving assistance ECU 10 determines the distance dL in the road width direction between the center position in the vehicle width direction of the host vehicle 100 and the center line LM, and the direction of the center line LM (tangential direction). And the deviation angle θL (yaw angle θL) between the vehicle 100 and the traveling direction of the host vehicle 100 are calculated. When the driving support ECU 10 sets the center line LM of the driving lane as the target driving line, the driving support ECU 10 sets target driving path information (curvature CL of the target driving line, yaw angle θL with respect to the target driving line, And the distance dL) in the road width direction with respect to the target travel line.

The driving assistance ECU 10 calculates the target steering angle θ * by applying the curvature CL, the yaw angle θL, and the distance dL to the following equation (3) every time a predetermined time elapses. Furthermore, the driving assistance ECU 10 controls the steering motor 42 using the steering ECU 40 so that the actual steering angle θ matches the target steering angle θ *. In equation (3), Klta1, Klta2, and Klta3 are predetermined control gains.
θ * = Klta1 · CL + Klta2 · θL + Klta3 · dL (3)

The driving assistance ECU 10 calculates a target yaw rate YRc *, which is a yaw rate necessary for the host vehicle 100 to travel along the target travel line, by the following equation (3 ′), and the target yaw rate YRc * and the actual yaw rate YRt. Based on the above, the target steering torque Tr * for obtaining the target yaw rate YRc * may be calculated using a lookup table. In this case, the driving assistance ECU 10 controls the steering motor 42 using the steering ECU 40 so that the actual steering torque Tra matches the target steering torque Tr *. In the expression (3 ′), K1, K2, and K3 are control gains.
YRc * = K1 · dL + K2 · θL + K3 · CL (3 ′)

  Next, a description will be given of the lane keeping control using the target travel line determined based on the preceding vehicle locus. This lane keeping control is executed, for example, when the left and right white lines cannot be recognized. As shown in FIG. 3, the driving assistance ECU 10 specifies the preceding vehicle 101 that is the target for which the preceding vehicle locus L1 is to be created, and the position information of the preceding vehicle 101 for each predetermined time with respect to the position of the host vehicle 100. The preceding vehicle locus L1 is created based on the target information including 3, the central axis extending in the front-rear direction of the host vehicle 100 is the x axis, and the axis orthogonal thereto is the y axis, and the current position of the host vehicle 100 is the origin (x = 0, The coordinates are y = 0).

Each symbol shown in FIG. 3 is as follows.
dv: Distance in the road width direction between the center position in the vehicle width direction of the host vehicle 100 at the current position (x = 0, y = 0) and the preceding vehicle locus L1 θv: Current position of the host vehicle 100 (x = 0) , Y = 0), the deviation angle (yaw angle) between the direction of the preceding vehicle locus L1 (tangential direction) and the traveling direction of the host vehicle 100 (+ direction of the x axis)
Cv: Curvature of the preceding vehicle locus L1 at the position (x = 0, y = dv) corresponding to the current position (x = 0, y = 0) of the host vehicle 100 Cv ′: Curvature change rate (arbitrary change of the preceding vehicle locus L1) Of curvature per unit distance (Δx) at x position (x = x0, x0 is an arbitrary value)

  For example, the driving assistance ECU 10 stores (buffers) position information representing the coordinate value of the position of the preceding vehicle 101 in the RAM every time a predetermined time elapses. In order to reduce the data to be saved as much as possible, the driving assistance ECU 10 may save only a certain number of coordinate values from the latest coordinate values of the preceding vehicle 101 and sequentially discard the old coordinate values. The driving support ECU 10 determines the difference between the coordinate value of the preceding vehicle 101 stored in the RAM and the position and traveling direction of the own vehicle 100 at the time when each coordinate value is acquired and the current position and traveling direction of the own vehicle. Based on this, the current position is converted into the coordinates of the above-described xy coordinates with the origin (x = 0, y = 0). (X1, y1), (x2, y2), (x3, y3) and (x4, y4) in FIG. 3 are examples of the coordinates of the position of the preceding vehicle 101 thus converted.

  The driving assistance ECU 10 creates a preceding vehicle locus L1 of the preceding vehicle by executing a curve fitting process on these coordinate values. For example, the curve used for the fitting process is a cubic function f (x). The fitting process is executed by, for example, the least square method. As described above, the driving support ECU 10 has a “travel locus creating unit (travel locus creating means) 10 c that creates the preceding vehicle locus L1” that is functionally realized by the CPU.

As shown in FIG. 4A, the preceding vehicle locus L1 is defined by a cubic function: f (x) = ax ³ + bx ² + cx + d. When the relational expression and conditions shown in FIG. 4B are used, the relationship between the coefficient of the cubic function shown in FIG. 4C, the curvature, the yaw angle, and the like is derived. Therefore, the preceding vehicle locus L1 can be expressed as shown in the following equation (4). As is clear from the above, by obtaining the coefficients a, b, c, and d of the cubic function f (x), the curvature change rate Cv ′ of the preceding vehicle locus L1 and the position corresponding to the current position of the host vehicle 100 can be obtained. The curvature Cv, the yaw angle θv, and the distance dv of the preceding vehicle locus L1 can be obtained.
f (x) = (1/6) Cv ′ · x ³ + (1/2) Cv · x ² + θv · x + dv (4)

  When setting the preceding vehicle locus L1 as the target travel line, the driving assistance ECU 10 determines from the coefficients a, b, c and d of the generated cubic function f (x) and the relationship shown in FIG. , Target lane information (ie, curvature Cv (and curvature change rate Cv ′) of the target travel line, yaw angle θv with respect to the target travel line, and distance dv in the road width direction with respect to the target travel line) necessary for lane keeping control. get.

  Then, the driving support ECU 10 calculates the target steering angle θ * by substituting dL for dv, substituting θL for θv, and substituting CL for Cv in Equation (3), and calculates the actual steering angle θ. Is controlled so as to match the target steering angle θ *. Note that the driving assistance ECU 10 may control the steering motor 42 by using the expression (3 ′).

  Further, the driving assistance ECU 10 may create a target travel line by a combination of the preceding vehicle locus L1 and the center line LM of the travel lane. More specifically, for example, as shown in FIG. 5, the driving assistance ECU 10 determines that the preceding vehicle locus L1 is “a locus in which the shape (curvature) of the preceding vehicle locus L1 is maintained and in the vicinity of the host vehicle 100. The preceding vehicle locus L1 can be corrected so that the locus coincides with the position of the center line LM and the direction (tangential direction) of the center line LM. As a result, “the corrected preceding vehicle locus (which may be referred to as“ corrected preceding vehicle locus ”) L2” is a locus in which the shape of the preceding vehicle locus L1 is maintained and the error in the lane width direction is small. Can be obtained as a target travel line.

For example, as shown in (a) to (d) described below, the driving assistance ECU 10 sets the target travel line according to the presence / absence of the preceding vehicle and the recognition status of the white line, and executes the lane keeping control.
(A) When the left and right white lines can be recognized far, the driving assistance ECU 10 sets the target travel line based on the center line LM of the travel lane and executes the lane keeping control.
(B) When a preceding vehicle exists ahead of the host vehicle and the left and right white lines cannot be recognized, the driving assistance ECU 10 sets a target travel line based on the preceding vehicle locus L1 and executes lane keeping control.
(C) When there is a preceding vehicle ahead of the host vehicle and the vicinity of the left and right white lines of the host vehicle can be recognized, the driving assistance ECU 10 performs the target travel on the corrected preceding vehicle locus obtained by correcting the preceding vehicle locus L1 with the white line. Set as a line and execute lane keeping control.
(D) When there is no preceding vehicle ahead of the host vehicle and the white line on the road cannot be recognized far away, the driving assistance ECU 10 cancels the lane keeping control.

  As described above, the driving support ECU 10 is functionally realized by the CPU “the LTC control unit (lane maintaining control means for performing the lane maintaining control for performing the steering assist for causing the host vehicle to travel along the target traveling line”). ) 10d ".

<Determining the reliability of the center line LM of the driving lane>
Next, referring to FIG. 6 and FIG. 7, the “determination process of the reliability of the center line LM of the travel lane” that is one process in the lane keeping control performed by the driving assistance ECU 10 will be described. 6 and 7, the time in a certain calculation cycle is expressed as t = t1, and the time in the next calculation cycle is expressed as t = t2. In FIG. 6, the preceding vehicle is not shown. Furthermore, in the examples shown in FIGS. 6 and 7, the camera sensor 16b can recognize the white line far (including erroneous recognition of the white line), and the preceding vehicle 101 exists in front of the host vehicle 100. It is assumed that Furthermore, the driving assistance ECU 10 executes lane keeping control according to the target travel line set based on the central line LM.

  As shown in FIG. 6A, at time t1, the driving assistance ECU 10 correctly recognizes the left white line LL and the right white line LR by the camera sensor 16b. The driving assistance ECU 10 estimates the center line LM of the traveling lane based on the recognized white lines LL and LR. Then, the driving assistance ECU 10 calculates a distance in the road width direction (hereinafter, referred to as “first center distance”) dL1 between the center position in the vehicle width direction of the host vehicle 100 and the center line LM of the travel lane. And stored in the RAM.

  Next, as shown in FIG. 6B, it is assumed that the left white line LL of the travel lane in which the host vehicle 100 travels is thin at time t2. The driving assistance ECU 10 erroneously recognizes the curb LC provided along the left white line LL as a left white line. Therefore, at time t2, the driving assistance ECU 10 estimates the center line LM ′ of the travel lane based on the recognized curb LC and the white line LR. Thus, at time t2, the position of the center line of the travel lane moves to the position (LM ′) on the curb LC side with respect to the correct center line position (LM).

  The driving assistance ECU 10 calculates the first center distance dL2 at time t2 and stores it in the RAM. Then, the driving assistance ECU 10 determines the amount of change in the first center distance between the previous calculation cycle (time t1) and the current calculation cycle (time t2) (that is, the first predetermined time (t2-t1). ), The first distance change amount (| dL2-dL1 |), which is the magnitude of the change amount of the first center distance in). The driving assistance ECU 10 determines whether or not the first distance change amount (| dL2-dL1 |) is equal to or greater than a predetermined first threshold value Th1.

  When the first distance change amount (| dL2-dL1 |) is smaller than the predetermined first threshold Th1, the driving assistance ECU 10 determines that the reliability of the center line of the travel lane is high.

  On the other hand, in the example of FIG. 6B, since the curb LC is erroneously recognized as the left white line, the first distance change amount (| dL2-dL1 |) becomes larger than the predetermined first threshold Th1. In this way, when the first distance change amount is large, there is a high possibility that the white line is erroneously recognized. However, as described below, even when the first distance change amount is large, there is a case where the white line is not erroneously recognized. For example, when the position of the host vehicle 100 is at a position away from the position of the center line LM of the travel lane when the lane maintenance control is started, the position of the host vehicle 100 becomes the position of the travel lane with the start of the lane maintenance control. It moves toward the position of the center line LM. In this case, the first distance change amount is increased, but no white line is erroneously recognized. Thus, even when the first distance change amount is large, the white line may not be erroneously recognized. Therefore, the driving assistance ECU 10 executes the following processing in addition to the white line reliability determination using the first distance change amount.

  As shown in FIG. 7A, at time t1, the driving assistance ECU 10 determines the distance in the road width direction (hereinafter referred to as “second”) between the center position in the vehicle width direction of the host vehicle 100 and the preceding vehicle locus L1. This is referred to as “center distance.”) Dv1 is calculated and stored in the RAM.

  As shown in FIG. 7B, the driving assistance ECU 10 calculates the second center distance dv2 at time t2 and stores it in the RAM. The driving assistance ECU 10 determines the amount of change in the second center distance between the previous calculation cycle (time t1) and the current calculation cycle (time t2) (that is, at the first predetermined time (t2-t1)). A second distance change amount (| dv2-dv1 |) which is a magnitude of the change amount of the second center distance) is calculated. Furthermore, the driving assistance ECU 10 determines whether or not the second distance change amount (| dv2−dv1 |) is equal to or smaller than a predetermined second threshold Th2.

  Since the position of the host vehicle 100 has not changed with respect to the preceding vehicle locus L1 of the preceding vehicle 101 between the time t1 and the time t2, the second distance change amount (| dv2-dv1 |) is a predetermined second value. It is below the threshold Th2. As described above, when the first distance change amount is large and the second distance change amount is small, this is because the change amount of the distance between the host vehicle 100 and the preceding vehicle locus L1 is small. It means that only the distance between the vehicle 100 and the center line LM of the travel lane has changed abruptly. Therefore, there is a high possibility that erroneous recognition of white lines has occurred. In the driving assistance ECU 10, the first distance change amount (| dL2-dL1 |) is equal to or larger than a predetermined first threshold value Th1, and the second distance change amount (| dv2-dv1 |) is equal to or smaller than a predetermined second threshold value Th2. If it is, it is determined that the reliability of the center line LM of the traveling lane is low.

  On the other hand, in the driving assistance ECU 10, the first distance change amount (| dL2-dL1 |) is equal to or greater than a predetermined first threshold value Th1, and the second distance change amount (| dv2-dv1 |) is a predetermined second threshold value. When it is larger than Th2, it is determined that the reliability of the center line LM of the traveling lane is high. For example, when the own vehicle 100 is at a position away from the position of the center line LM of the travel lane when the lane keeping control is started, the position of the host vehicle 100 is changed to the center line of the travel lane with the start of the lane keeping control. Approach toward the position of LM. At this time, since the host vehicle 100 itself moves, if the preceding vehicle 101 is not moving in the road width direction (that is, if the preceding vehicle 101 is traveling along the traveling lane), the host vehicle 100 and the preceding vehicle 100 are preceded. The distance to the vehicle locus L1 also changes. Thus, when the first distance change amount is equal to or greater than the first threshold value and the second distance change amount is greater than the second threshold value, the white line is not erroneously recognized, and the lane keeping control is normally performed. It is considered to be executed.

  When it is determined that the reliability of the center line LM of the traveling lane is low, the driving assistance ECU 10 does not determine that the reliability of the central line LM of the traveling lane is low (when the reliability is determined to be high). ), The responsiveness of the lane keeping control until the position and direction of the host vehicle coincide with the target travel line (in this case, the center line LM) is reduced.

  More specifically, the driving assistance ECU 10 determines the magnitude of the steering control amount when it is determined that the reliability of the center line LM of the traveling lane is low, compared with the case where it is determined that the reliability is high. Change the upper limit value of to a smaller value. The driving assistance ECU 10 performs a limiting process so that the magnitude of the steering control amount does not exceed the upper limit value, and executes steering control (lane keeping control) for changing the steering angle based on the steering control amount subjected to the limiting process. To do.

  The steering control amount is a parameter that determines the steering angle of the host vehicle, and includes at least one of the target steering angle θ * and the target steering angular velocity.

  The driving assistance ECU 10 of the present embodiment employs the target steering angle θ * and the target steering angular velocity as the steering control amount. More specifically, the driving assistance ECU 10 determines that the target steering angle θ * does not exceed the first steering angle upper limit value θ1max when it is determined that the reliability of the center line LM of the travel lane is high. Limit the steering angle θ *. In this case, when the magnitude of the target steering angle θ * exceeds the first steering angle upper limit value θ1max, the driving assistance ECU 10 sets the magnitude of the target steering angle θ * to the first steering angle upper limit value θ1max.

Further, when it is determined that the reliability of the center line LM of the driving lane is high, the driving assistance ECU 10 limits the steering angular velocity to the steering angular velocity so that the steering angular velocity does not exceed the first steering angular velocity upper limit value dθ1max (> 0). Add More specifically, when the target steering angle θ * a predetermined time before the current time is expressed as θold and the current target steering angle θ * is expressed as θnow, the driving assistance ECU 10 sets the target steering angle as follows. Limit θ *.
The driving support ECU 10 sets the target steering angle θ * to a value (θold + dθ1max) when θnow−θold> dθ1max.
The driving support ECU 10 sets the target steering angle θ * to a value (θold−dθ1max) when θold−θnow> dθ1max.

  On the other hand, when the driving assistance ECU 10 determines that the reliability of the center line LM of the travel lane is low, the target steering angle θ * is “the second steering angle smaller than the first steering angle upper limit value θ1max”. The target steering angle θ * is limited so as not to exceed the “upper limit value θ2max”. In this case, when the magnitude of the target steering angle θ * exceeds the second steering angle upper limit value θ2max, the driving assistance ECU 10 sets the magnitude of the target steering angle θ * to the second steering angle upper limit value θ2max.

Further, when it is determined that the reliability of the center line LM of the travel lane is low, the driving assistance ECU 10 limits the steering angular velocity so that the steering angular velocity does not exceed the second steering angular velocity upper limit value dθ2max (> 0). Add More specifically, the driving assistance ECU 10 limits the target steering angle θ * as follows.
The driving support ECU 10 sets the target steering angle θ * to a value (θold + dθ2max) when θnow−θold> dθ2max.
The driving assistance ECU 10 sets the target steering angle θ * to a value (θold−dθ2max) when θold−θnow> dθ2max.

  Accordingly, the driving assistance ECU 10 can reduce the responsiveness of the lane keeping control, and as a result, can prevent the position and direction of the host vehicle 100 from changing suddenly due to erroneous recognition of the white line. The first steering angle upper limit value θ1max and / or the first steering angular velocity upper limit value dθ1max may be a very large value (a value having a magnitude that cannot be obtained in the lane keeping control). In this case, when it is determined that the reliability of the center line LM of the traveling lane is high, no restriction is effectively imposed on the target steering angle θ * and / or the target steering angular velocity.

  Furthermore, the driving assistance ECU 10 determines that the magnitude of the control gain Klta2 and / or the control gain Klta3 in the above equation (3) is low in the reliability of the center line LM of the travel lane, the center line LM of the travel lane. It may be set to a smaller value compared to the case where it is determined that the reliability is high. Also by this, the driving assistance ECU 10 can reduce the responsiveness of the lane keeping control.

  Further, when the driving assistance ECU 10 is configured to execute the lane keeping control using the above equation (3 ′), even if the steering control amount is the target steering torque Tr * and / or the target yaw rate YRc *. good. In this case, the upper limit value of each of these values may be changed according to whether the reliability of the center line LM of the traveling lane is high or low. Further, the driving assistance ECU 10 has a high reliability of the center line LM of the traveling lane when it is determined that the control gain of the expression (3 ′) is low in the reliability of the central line LM of the traveling lane. It may be set to a smaller value as compared with the case where it is determined. Also by these, the driving assistance ECU 10 can reduce the responsiveness of the lane keeping control when it is determined that the reliability of the center line LM of the traveling lane is low.

<Specific operation>
Next, a specific operation of the CPU (which may be simply referred to as “CPU”) of the driving assistance ECU 10 will be described. The CPU executes the routine shown in FIG. 8 as one routine in the lane keeping control (LTC) every time a predetermined time elapses. The CPU executes follow-up inter-vehicle distance control (ACC) by a routine not shown. The CPU executes the routine shown in FIG. 8 when the following inter-vehicle distance control is executed.

  Therefore, when the following inter-vehicle distance control is being executed, when the predetermined timing is reached, the CPU starts the routine of FIG. 8 from step 800 and proceeds to step 810 to determine whether or not a predetermined execution condition is satisfied. Determine.

The predetermined execution condition is satisfied when all of the following conditions 1 to 3 are satisfied.
(Condition 1): The white line can be recognized far by the camera sensor 16b (including erroneous recognition of the white line).
(Condition 2): A preceding vehicle 101 (in this case, a tracking target vehicle in the tracking inter-vehicle distance control) exists in front of the host vehicle 100.
(Condition 3): The CPU executes the lane keeping control according to the target travel line set based on the central line LM.

  If the execution condition is not satisfied, the CPU makes a “No” determination at step 810 to proceed to step 895 to end the present routine tentatively.

  On the other hand, if the execution condition is satisfied, the CPU makes a “Yes” determination at step 810 to proceed to step 815.

  Step 815: The CPU selects the preceding vehicle 101 for which the preceding vehicle locus L1 is to be created. More specifically, the CPU acquires the vehicle speed of the host vehicle 100 from the vehicle speed sensor 15 and acquires the yaw rate of the host vehicle 100 from the yaw rate sensor 18. The CPU estimates the traveling direction of the host vehicle 100 from the acquired vehicle speed and yaw rate, and selects the target closest to the traveling direction based on the target information sent from the surrounding sensor 16 as “create the preceding vehicle locus L1. The vehicle is selected as the target preceding vehicle 101 ”.

  Step 820: The CPU stores the target information of each target in the RAM in correspondence with each target based on the target information from the surrounding sensor 16. The CPU acquires position information (coordinate values of the preceding vehicle) corresponding to the preceding vehicle 101 selected in step 815 from the target information. As described above, the CPU creates the preceding vehicle locus L1 by executing the curve fitting process on the position information.

  Step 825: Based on information from the surrounding sensor 16 (information that can be recognized by the camera sensor 16b), the CPU acquires “left white line LL and right white line LR” of the traveling lane in which the vehicle 100 is traveling. . The CPU estimates a line connecting the center positions of the acquired pair of white lines, and determines the line as the “travel lane center line LM”.

  Step 830: The CPU sets the center line LM of the travel lane as the target travel line. As another example, as illustrated in FIG. 5, the CPU may set the corrected preceding vehicle locus L2 created based on both the center line LM and the preceding vehicle locus L1 of the traveling lane as the target traveling line. .

  Next, in step 835, the CPU calculates a first distance change amount (| dL2) that is a change amount between the first center distance dL1 in the previous calculation cycle and the first center distance dL2 in the current calculation cycle. It is determined whether or not −dL1 |) is equal to or greater than a predetermined first threshold Th1.

  If the first distance change amount (| dL2-dL1 |) is equal to or greater than the predetermined first threshold value Th1, the CPU makes a “Yes” determination at step 835 to proceed to step 840. In step 840, the CPU calculates a second distance change amount (| dv2-dv1 |) that is a change amount between the second center distance dv1 in the previous calculation cycle and the second center distance dv2 in the current calculation cycle. ) Is less than or equal to a predetermined second threshold Th2. When the second distance change amount (| dv2−dv1 |) is equal to or smaller than the predetermined second threshold Th2, the CPU makes a “Yes” determination at step 840 to proceed to step 845.

  In step 845, the CPU determines that the reliability of the central line LM of the travel lane is low, and executes steering control with a relatively low steering control amount as described above (that is, the reliability of the central line LM is low). The upper limit value of the steering control amount is set to be smaller than when it is determined to be high). As a result, the responsiveness of the lane keeping control until the position and direction of the host vehicle coincide with the target travel line (in this case, the center line) is lowered. Thereafter, the CPU proceeds to step 895 to end the present routine tentatively.

  On the other hand, if the first distance change amount (| dL2-dL1 |) is smaller than the first threshold value Th1, the CPU makes a “No” determination at step 835 to proceed to step 850.

  If the second distance change amount (| dv2−dv1 |) is larger than the second threshold Th2, the CPU makes a “No” determination at step 840 to proceed to step 850.

  When the CPU proceeds to step 850, the CPU determines that the reliability of the center line LM of the traveling lane is high, and executes the steering control with a relatively high steering control amount as described above (that is, the reliability of the center line LM). The upper limit value of the steering control amount is set to be larger than when it is determined that is low). As a result, the responsiveness of the lane keeping control until the position and direction of the host vehicle coincide with the target travel line (in this case, the center line) is improved. Thereafter, the CPU proceeds to step 895 to end the present routine tentatively.

  In the embodiment described above, the first distance change amount (| dL2-dL1) that is the magnitude of the change amount in the first predetermined time of the distance in the road width direction between the center line LM of the traveling lane and the host vehicle 100 is obtained. |) And the second distance change amount (| dv2-dv1 |) that is the magnitude of the change amount in the first predetermined time of the distance in the road width direction between the preceding vehicle locus L1 and the host vehicle 100. The reliability of the center line LM of the traveling lane is determined. Accordingly, it is possible to reduce the possibility that the position and orientation of the host vehicle 100 change suddenly due to erroneous recognition of the white line.

  In addition, this invention is not limited to the said embodiment, A various modification can be employ | adopted within the scope of the present invention.

  In step 835, the CPU replaces the first distance change amount (| dL2-dL1 |) with a second deviation angle θL (see FIG. 2) between the direction of the center line LM and the traveling direction of the host vehicle 100. You may calculate the magnitude | size of the variation | change_quantity in predetermined time. Hereinafter, the deviation angle θL is referred to as a “first yaw angle”. For example, when the curb is mistakenly recognized as a white line, the center line LM ′ is curved toward the curb at the portion where the misrecognition occurs, and the first yaw angle θL is increased. Therefore, the first yaw angle θL can be used as a condition for determining whether or not the white line is erroneously recognized. Specifically, the CPU determines the amount of change between the first yaw angle θL1 in the previous calculation cycle and the first yaw angle θL2 in the current calculation cycle (the first yaw angle at the second predetermined time). The first angle change amount (| θL2−θL1 |), which is the magnitude of the change amount), is calculated. The CPU determines whether or not the first angle change amount (| θL2−θL1 |) is equal to or greater than a predetermined third threshold Th3. If the first angle change amount (| θL2−θL1 |) is equal to or greater than the predetermined third threshold Th3, the CPU proceeds to step 840. On the other hand, if the first angle change amount (| θL2−θL1 |) is smaller than the predetermined third threshold Th3, the CPU proceeds to step 850.

  When the determination using the first angle change amount (| θL2-θL1 |) is performed in step 835, the CPU replaces the second distance change amount (| dv2-dv1 |) in step 840 with the preceding vehicle. You may calculate the magnitude | size of the variation | change_quantity in 2nd predetermined time of deviation | shift angle (theta) v (refer FIG. 4 (A)) of the direction of the locus | trajectory L1 and the advancing direction of the own vehicle 100. FIG. Hereinafter, the deviation angle θv is referred to as a “second yaw angle”. Specifically, the CPU changes the amount of change between the second yaw angle θv1 in the previous calculation cycle and the second yaw angle θv2 in the current calculation cycle (the amount of change in the second yaw angle in the second predetermined time). The second angle change amount (| θv2−θv1 |) is calculated. The CPU determines whether or not the second angle change amount (| θv2−θv1 |) is equal to or smaller than a predetermined fourth threshold Th4. If the second angle change amount (| θv2−θv1 |) is equal to or smaller than the predetermined fourth threshold value Th4, the CPU proceeds to step 845. On the other hand, if the amount of change in the second yaw angle (| θv2−θv1 |) is larger than the predetermined fourth threshold Th4, the CPU proceeds to step 850.

  Further, the CPU may use both the first distance change amount and the first angle change amount in step 835. In this case, when the first distance change amount (| dL2-dL1 |) is equal to or greater than the first threshold Th1, and the first angle change amount (| θL2-θL1 |) is equal to or greater than the third threshold Th3. The process proceeds to step 840. On the other hand, when the first distance change amount (| dL2-dL1 |) is smaller than the first threshold Th1 and / or the first angle change amount (| θL2-θL1 |) is smaller than the third threshold Th3, the CPU Proceed to step 850.

  In addition, in step 840, the CPU may use both the second distance change amount and the second angle change amount. In this case, the CPU has the second distance change amount (| dv2-dv1 |) equal to or smaller than the second threshold Th2 and the second angle change amount (| θv2-θv1 |) equal to or smaller than the fourth threshold Th4. The process proceeds to step 845. On the other hand, if the second distance change amount (| dv2-dv1 |) is larger than the second threshold Th2 and / or the second angle change amount (| θv2-θv1 |) is larger than the fourth threshold Th4, the CPU Proceeds to step 850.

  In step 820, the CPU may generate a preceding vehicle locus L1 using a Kalman filter. When the position information of the host vehicle is input to the Kalman filter included in the driving assistance ECU 10, the curvature Cv of the preceding vehicle locus L1 at the current position of the own vehicle 100, the curvature change rate Cv ′ of the preceding vehicle locus L1, and the preceding vehicle locus L1 from the Kalman filter. The yaw angle θv of the host vehicle 100 and the distance dv between the preceding vehicle locus L1 and the current position of the host vehicle 100 are output. The CPU obtains 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. 4C and the curvature and yaw angle. it can.

  In the present embodiment, the lane keeping control is executed only during the following inter-vehicle distance control (ACC), but the lane keeping control may be executed even when the following inter-vehicle distance control is not being executed. .

DESCRIPTION OF SYMBOLS 10 ... Driving assistance ECU, 11 ... Accelerator pedal operation amount sensor, 12 ... Brake pedal operation amount sensor, 13 ... Steering angle sensor, 14 ... Steering torque sensor, 15 ... Vehicle speed sensor, 16 ... Ambient sensor, 17 ... Operation switch, 18 ... yaw rate sensor, 20 ... engine ECU, 30 ... brake ECU, 40 ... steering ECU.

Claims (1)

A lane marking recognition means for recognizing a lane marking of a road on which the host vehicle is traveling, and estimating a central line that is a line connecting the central positions between the lane markings;
Traveling locus creating means for creating a traveling locus of a preceding vehicle traveling in front of the host vehicle;
Lane keeping control means for executing lane keeping control for changing the steering angle of the host vehicle so that the host vehicle travels along the target travel line set based on the center line;
With
The lane keeping control means is
When performing the lane keeping control,
A first distance change amount that is a magnitude of a change amount in a first predetermined time of a distance in the road width direction between the center line and the host vehicle and between the direction of the center line and the traveling direction of the host vehicle. At least one of a first angle change amount that is a magnitude of a change amount of the shift angle in a second predetermined time;
A second distance change amount, which is a magnitude of a change amount in the first predetermined time, of the distance in the road width direction between the travel locus and the host vehicle, the direction of the travel locus, and the traveling direction of the host vehicle; At least one of a second angle change amount that is a magnitude of a change amount in the second predetermined time of the deviation angle between
Based on whether or not the reliability of the central line is low,
When it is determined that the reliability of the center line is low, the lane until the position and orientation of the host vehicle is matched with the target travel line as compared with the case where it is determined that the reliability of the center line is not low. A driving assistance device configured to reduce responsiveness of maintenance control.

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