JP7184151B2 - Vehicle travel control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle cruise control system, and more particularly to a steering override function in an in-lane partially automated driving system.

Various technologies aimed at reducing the burden on the driver and supporting safe driving, such as an inter-vehicle distance control system (Adaptive Cruise Control System: ACCS), a lane keeping support system (LaneKeeping
Assistance System: LKAS) and the like have been put into practical use. Furthermore, based on these, "Partially Automated In-lane Driving System (PADS)
)” is being put into practical use and international standardization is underway.

Such cruise control systems have an override function that switches to manual operation by forced intervention of the driver during operation. For example, Patent Literature 1 discloses a control gain setting unit that variably sets a control gain when steering control is performed based on a steering target control amount. set smaller than the value at the time of intervention,
In addition, a travel control device is disclosed in which the value of the control gain when the host vehicle is turning is set to be larger than the value when the host vehicle is not turning when the vehicle is intervened in a driving operation.

JP 2016-97827 A

By the way, as shown in FIG. 4, when a malfunction occurs in the ACC system due to equipment failure or abnormality during operation of the PADS (61), the ACC function is stopped at the same time as the malfunction occurs.
A steering takeover request for CC function stop and LKA function stop is notified to the driver (62), and LK
It is set to shift to the A degeneracy control mode. Several seconds after the notification, the LKA degeneration control starts (63), the LKA degeneration control ends, and the steering is handed over to the driver (64).

In such a system, for example, in order to follow the route in the vicinity of the lane center 51c by the LKA function, if the ACC system malfunctions during either the left or right automatic steering, the LKA function is stopped until the LKA function stops. Since the degeneration control mode is entered, if the driver applies corrective steering such as turning the steering wheel more during the LKA degeneration control, excessive forward steering may be performed.

Furthermore, there is a possibility that the driver who has panicked at the function stop/takeover request notification may perform excessive steering (steering override). There is also a risk of repeating excessive steering override and corrective steering for steering.

SUMMARY OF THE INVENTION The present invention has been made in view of the actual situation as described above, and its object is to provide a vehicle cruise control apparatus capable of preventing excessive steering override in the transition process to LKA degeneracy control when ACC malfunctions. to do.

In order to solve the above problems, the present invention
an environmental state estimating unit including a surrounding recognition function for recognizing the vehicle's driving lane and other vehicles traveling in the driving lane and a function for acquiring the vehicle's motion state;
a route generation unit that generates a target route based on information acquired by the environmental state estimation unit;
a vehicle control unit that performs speed control and steering control to cause the vehicle to follow the target route;
A vehicle travel control device comprising:
an ACC function that performs constant speed driving according to the target vehicle speed when there is no preceding other vehicle in the lane in which the vehicle is traveling, and performs follow-up driving while maintaining a predetermined inter-vehicle distance when there is another preceding vehicle;
an LKA function that maintains traveling within the own vehicle traveling lane by follow-up control to the target route;
a steering override function that stops the LKA function by a driver's steering intervention;
a function of notifying the driver of the suspension of the LKA function and the steering takeover when the ACC function fails, and performing degeneration control of the LKA function;
in those having
The steering torque or steering angle override threshold that serves as a criterion for steering intervention to stop the LKA function includes an override threshold for normal operation of the ACC function and an override threshold for failure of the ACC function. ,
The override threshold when the ACC function is normal differs depending on whether the steering direction is forward steering or reverse steering with respect to the steering direction at the time of the steering intervention. It is characterized in that the steering direction differs between forward steering and reverse steering with respect to the steering direction at the time of steering intervention.

According to the vehicle cruise control device according to the present invention, the steering torque or steering angle override threshold, which serves as a criterion for determining the steering intervention for stopping the LKA function, is the override threshold when the ACC function is normal and the override threshold when the ACC function is malfunctioning. and the override threshold of , and the override threshold at the time of ACC function failure is applied while the ACC function failure and the steering takeover are notified and the degeneration control of the LKA function is performed, so the override due to the driver's oversteering As a result, it is possible to prevent lane departure and repetition of corrective steering due to this, which is advantageous in performing smooth steering handover. In addition, since the override threshold is different between forward steering and reverse steering with respect to the steering direction at the time of steering intervention, it is possible to effectively prevent oversteering according to the running state of the vehicle when the ACC function fails. has the advantage of being able to

1 is a schematic diagram showing a vehicle travel control system; FIG. 2 is a schematic plan view showing a group of external sensors of a vehicle; FIG. 1 is a block diagram showing a vehicle travel control system; FIG. FIG. 4 is a schematic plan view showing LKA degeneracy control when ACC malfunctions; FIG. 5 is a schematic plan view showing an example of oversteering prevention control when ACC malfunctions. FIG. 5 is a schematic plan view showing another example of oversteering prevention control when ACC malfunctions. 4 is a flow chart showing oversteering prevention control at the time of ACC malfunction.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In FIG. 1, a vehicle 1 equipped with a cruise control system according to the present invention includes general automobile components such as an engine and a vehicle body. , an external sensor 21 for detecting the vehicle surrounding environment, and an internal sensor 2 for detecting vehicle information.
2. A group of controllers/actuators for speed control and steering control, an ACC controller 14 for inter-vehicle distance control, an LKA controller 15 for lane keeping support control, and for integrating them to implement route following control. of the automatic operation controller 10.

A controller/actuator group for speed control and steering control includes an EPS (electric power steering) controller 31 for steering control, an engine controller 32 for acceleration/deceleration control, and an ESP/ABS controller 33 . ESP (registered trademark; Electronic Stability Program) includes ABS (anti-lock braking system) to constitute a stability control system (vehicle behavior stabilization control system).

The external sensor 21 detects the division lines 5s and 5 on the road that define the own lane 51 and the adjacent lane 52.
c. It consists of a plurality of detection means for inputting the presence and relative distance of other vehicles, obstacles, people, etc. around the own vehicle to the automatic driving controller 10 as image data and point cloud data.

For example, as shown in FIG. 2, the vehicle 1 includes a millimeter wave radar (211) and a camera (212) as forward detection means 211 and 212, front side detection means 213 and rear side detection means 21.
4 is LIDAR (laser image detection/ranging), and a camera (rear camera) is provided as rear detection means 215, covering 360 degrees around the vehicle, and detecting vehicles and obstacles within a predetermined distance in the front, rear, left, and right directions of the vehicle. It is designed to be able to detect position, distance, and lane marking position.

The internal sensor 22 consists of a plurality of detection means for measuring physical quantities representing the motion state of the vehicle, such as a vehicle speed sensor, a yaw rate sensor, an acceleration sensor, etc. As shown in FIG. , ACC controller 14, LKA controller 15,
and input to the EPS controller 31 .

The automatic driving controller 10 includes an environmental state estimation unit 11, a route generation unit 12, and a vehicle control unit 13, and is a computer for performing the functions described below, that is, a ROM storing programs and data , a CPU that performs arithmetic processing, a RAM that reads the programs and data, stores dynamic data and arithmetic processing results, and an input/output interface.

The environmental state estimation unit 11 acquires the absolute position of the own vehicle using a positioning means 24 such as GPS, and determines the own lane 5 based on external data such as image data and point cloud data acquired by the external sensor 21 .
1 and adjacent lane 52 lane marking position, other vehicle position and speed are estimated. Also, the motion state of the own vehicle is acquired from the internal world data measured by the internal sensor 22 .

The route generator 12 generates a target route from the vehicle position estimated by the environmental state estimator 11 to the target. Also, with reference to the map information 23, based on the lane marking position of the adjacent lane, the position and speed of the other vehicle, and the motion state of the vehicle, which are estimated by the environmental state estimation unit 11, the target point is calculated from the vehicle position when changing lanes. Generate a target route to

The vehicle control unit 13 calculates a target vehicle speed and a target steering angle based on the target route generated by the route generation unit 12, and transmits to the ACC controller 14 a speed command for constant speed running or inter-vehicle distance maintenance/follow-up running. Then, the steering angle command for track tracking is sent to the EP via the LKA controller 15
It is transmitted to the S controller 31 .

The vehicle speed is also input to the EPS controller 31 and the ACC controller 14 . Since the steering torque varies depending on the vehicle speed, the EPS controller 31 refers to the steering angle-steering torque map for each vehicle speed and transmits a torque command to the steering mechanism 41 . The engine controller 32, the ESP/ABS controller 33, and the EPS controller 31 control the engine 42
, the brakes 43 and the steering mechanism 41 control the longitudinal and lateral movements of the vehicle 1 .

(Overview of in-lane partially automated driving system)
Next, an outline of the in-lane partially automated driving system (PADS) will be described, assuming that the vehicle travels in a single lane while following a preceding vehicle on a highway.

In-lane partially automated driving (PADS driving) uses ACC together with the automated driving controller 10
ACC controller 14 that configures S and LKA controller 15 that configures LKAS
are working together.

At the same time that the in-lane partial automatic driving system is activated, the automatic driving controller 10 (route generation unit 12) receives external world information (lane, vehicle position, vehicle driving lane and A single-lane target route and target vehicle speed are generated based on the position and speed of other vehicles traveling in adjacent lanes) and internal world information (vehicle speed, yaw rate, acceleration) acquired by the internal sensor 22 .

The automatic driving controller 10 (vehicle control unit 13) determines the position of the vehicle and the motion characteristics of the vehicle, that is, the front wheel steering angle δ generated when the steering torque T is applied to the steering mechanism 41 while traveling at the vehicle speed V. From the relationship between the yaw rate γ caused by motion and the lateral acceleration (d ² y/dt ² ),
After Δt seconds, the speed, attitude, and lateral displacement of the vehicle are estimated, and a steering angle command is given to the EPS controller 31 via the LKA controller 15 so that the lateral displacement becomes yt after Δt seconds. speed command to the ACC controller 14.

During partially automated driving within the lane, the external sensor 21 recognizes the preceding vehicle in front of the own lane and the lane markings of the own lane, and constantly monitors so that the own vehicle follows the generated target route.

(Relationship with ACC, EPS, ESP/ABS, LKA, engine control)
The ACC controller 14, the LKA controller 15, the EPS controller 31, the engine controller 32, and the ESP/ABS controller 33 operate independently of the automatic steering, but the operation of the in-lane partial autonomous driving function (PADS). The inside can also be operated by command input from the automatic operation controller 10 .

The ESP/ABS controller 33, which has received the deceleration command from the ACC controller 14,
The vehicle speed is controlled by issuing a hydraulic command to the actuator and controlling the braking force of the brake 43 . Also, the engine controller 32 that receives the acceleration/deceleration command from the ACC controller 14
controls the actuator output (throttle opening) to give a torque command to the engine 42, and controls the driving force to control the vehicle speed.

The ACC function (ACCS) functions by a combination of hardware and software such as the millimeter wave radar 211 as the external sensor 21, the ACC controller 14, the engine controller 32, the ESP/ABS controller 33, and the like.

In other words, when there is no preceding vehicle, the cruise control set speed is used as the target vehicle speed, and when the preceding vehicle catches up (when the preceding vehicle speed is less than or equal to the cruise control set speed), , while following the preceding vehicle while maintaining the distance between vehicles according to the set time gap (time between vehicles = distance between vehicles / own vehicle speed).

The LKA function (LKAS) detects the lane markings and the position of the vehicle by the environmental state estimation unit 11 of the automatic driving controller 10 based on the image data acquired by the external sensor 21 (cameras 212, 215), and detects the lane center. Steering control is performed by the LKA controller 15 and the EPS controller 31 so that the vehicle can travel.

That is, the EPS controller 31 that receives the steering angle command from the LKA controller 15 refers to the vehicle speed-steering angle-steering torque map, issues a torque command to the actuator (EPS motor), and the steering mechanism 41 reaches the target Give the front wheel steering angle.

The in-lane partially automated driving function (PADS) is controlled by the ACC controller 14 as described above.
It is implemented by combining longitudinal control (speed control, vehicle-to-vehicle distance control) by the LKA controller 15 and lateral control (steering control, lane keeping control) by the LKA controller 15 .

(override function)
When the in-lane partially automated driving function (PADS) is in operation, the longitudinal control system (ACC
S) and Lateral Control System (LKAS) are both driver overrideable.

The longitudinal control system (ACCS) is overridden when the driver's accelerator pedal actuation engine torque request or brake pedal actuation deceleration request is equal to or greater than the respective override threshold. These override thresholds are set according to the acceleration/deceleration characteristics of the vehicle and the running state.

The Lateral Control System (LKAS) is overridden when the steering torque from the driver's manual steering 34 is greater than or equal to the override threshold. The override threshold for this steering intervention is set according to the steering characteristics of the vehicle and the running state.

Steering override is when the driver steers with the intention of changing course or avoiding obstacles.
Alternatively, when a steering torque that is judged to have been performed with an intention contrary to the LKA control (reverse steering) is applied by operating the steering wheel, the LKA control is stopped and the vehicle shifts to running by manual steering by the driver.

By the way, as shown in FIG. 4, when a malfunction of the ACCS occurs due to a failure of the forward detection millimeter wave radar or an ESP/ABS abnormality during operation of the in-lane partial automatic driving function (PADS) ( 61), the ACC function is stopped at the same time as the failure occurs, the LKAS shifts to the degeneration control mode, and the LKA function is stopped and the steering takeover request (takeover request) is notified to the driver (62), and several seconds (for example, 4 seconds), the LKA degeneracy control is started (6
3) When the steering torque reaches 0 (Nm), the LKA function is stopped and steering is handed over to the driver (64).

The LKA degeneracy control is set for the purpose of smoothly shifting to manual steering by gradually decreasing the steering torque command value input to the EPS controller 31 to 0 (Nm) with a predetermined slope.

As described above, if an ACCS malfunction occurs during operation of the in-lane partial automatic driving function, the ACC function and LKA function are stopped, and longitudinal control and lateral control by them are handed over to the driver. However, at that time, as already described, there is a risk of excessive steering (steering override) by the driver who has been flustered by the function stop/takeover request notification.

(Over-steering prevention function when ACCS function fails)
Therefore, in the automatic driving controller 10 according to the present invention, a malfunction of the ACCS occurs during operation of the in-lane partial automatic driving function, the ACC function and the LKA function are stopped, and the longitudinal control and lateral direction control are performed to the driver. When taking over, the period from partial automatic driving function stop in the lane (ACC function stop / LKA function stop notification) to LKA function stop (for example, 4 seconds after notification to LK
A degeneracy control start to LKA degeneracy control end) has an oversteering prevention function that changes the steering override threshold value to a value greater than that during normal operation.

By making the steering override threshold value larger than that during normal operation when the ACCS malfunctions, even if excessive steering torque is input to the EPS controller 31 by the driver's manual steering 34, the override state does not occur and the LKA control is performed. is continued, and the vehicle can be driven while maintaining the lane.

(Steering override threshold during normal operation)
The steering override threshold during normal ACCS operation is the vehicle speed V and the lateral acceleration limit value (for example, 1
m/s ² ), calculated from the virtual lateral displacement y′t (=yt+α) and the motion characteristics of the vehicle, based on the lateral movement distance yt for reaching the lane center position (1a) from the current position after t seconds. A value (steering torque calculated from a vehicle speed-steering angle-steering torque map) obtained by converting the steering angle to steering torque is set as an override threshold value T1d.

Specifically, the virtual lateral displacement y't for reaching the virtual lateral position (1d) after t seconds is yt+
A forward steering override threshold value T1d is defined as a steering torque corresponding to a steering angle that satisfies α (where α is a constant determined based on the vehicle speed).

In the case of reverse steering, the target lateral movement distance yt for reaching the target position (1a) after t seconds and the steering angle calculated from the motion characteristics of the vehicle are converted into steering torque (steering torque target value). is a value T2d which is applied in the direction of decreasing the steering torque and which can be determined not to be minute (determined by the steering angle, the steering angular velocity, etc.). Reverse steering can be regarded as a manifestation of the driver's intention to cancel the LKA control, so detection of reverse steering is overridden.

For example, it is assumed that a vehicle with a vehicle width of 1.7 m is running LKAS on a highway with a lane width of 3.5 m. As shown in FIG. 5, assuming that the vehicle 1 is traveling near the right edge of the lane 51 (in a slightly extreme position for ease of understanding), the vehicle lateral center G is the right lane division. It is about 0.9m from line 5c, and LKAS is near the center of lane 51c by left automatic steering,
That is, since the position is set around 1.75 m from the right lane marking 5c, the lateral displacement after t seconds is 1.75−0.9=0.85 m, α=0.43 m, and the lateral displacement after t seconds is is 1.28 m (
0.85+0.43) is set as the forward steering override threshold value T1d during normal operation.

On the other hand, the reverse steering override threshold value T2d is set according to the vehicle speed of the steering torque X'Nm (X'<X) that can be sensed to be applied in the direction of decreasing the steering torque XNm. Therefore, FIG. 5 does not show virtual lateral displacement as in the case of forward steering.

(Steering override threshold at malfunction)
To the forward steering override threshold T1d during normal ACCS operation, a value obtained by adding a steering torque that makes the lateral movement distance due to the driver's follow-up steering equal to or greater than a predetermined value (vehicle speed-steering angle-steering torque map and vehicle motion characteristics) set as consideration). If the steering torque is such that the lateral movement distance due to the driver's follow-up steering is equal to or less than a predetermined value, the steering torque is not overridden.

Specifically, the virtual lateral ^position ( 1e ₁
) to reach an imaginary lateral displacement y″ ₁ t (=yt+β, where β>α, β=2α in the illustrated example
) and a value obtained by converting the steering angle calculated from the motion characteristics of the vehicle into a steering torque is set as the forward steering override threshold value T1e.

For example, it is assumed that a vehicle with a vehicle width of 1.7 m is traveling in LKAS on a highway with a lane width of 3.5 m. As shown in FIG. 5, if the vehicle 1 is traveling near the right edge of the lane, the lateral movement distance yt required to reach the center position (1a) of the lane 51 from the current position after t seconds is 1.75. -0.9 = 0.85m, but when there is a malfunction, β = 0.85m and the steering angle is set so that the hypothetical lateral displacement after t seconds is 1.75m (= 0.9 + 0.85). A corresponding steering torque is set as the forward steering override threshold value T1e. Actual lateral displacement is 1
. Even if it is set to 75m, it is possible to maintain in-lane running.

On the other hand, the reverse steering override threshold T2e is the reverse steering override threshold T in normal operation.
By approximating the virtual lateral displacement equivalent to 2d as the lateral movement distance yt to reach the lane center position (1a) from the current position, the virtual lateral position (1e ₂ ) is reached after t seconds based on it. y″ ₂ t (=yt−γ, where γ is greater than the lateral displacement corresponding to the steering torque X′Nm, γ=α in the illustrated example) and the steering angle calculated from the motion characteristics of the vehicle. is converted into a steering torque and set as a reverse steering override threshold value T2e.

In this case, as shown in FIG. 5, γ=0.43 m, and the lateral displacement after t seconds is 0.42.
A steering torque corresponding to a steering angle of m (=0.85-0.43) is set as the reverse steering override threshold value T2e. As is clear from FIG. 5, the virtual lateral position (1e ₂ )
In-lane running can be maintained even in

(Another setting example of the steering override threshold at the time of malfunction)
FIG. 6 shows another setting example of the steering override threshold value when the ACCS function fails. In this example, a vehicle 1 with a width of 1.7 m is traveling in LKAS on a highway with a lane width of 3.5 m. It is assumed that

First, when the vehicle 1 is traveling 0.5 m to the right in the traveling direction from the lane center 51c, t
Lateral movement distance yt (=0.5 m) for reaching the lane center 51c from the current position in seconds,
t ₌ 3.5/ _2-1 . 7/2
= 0.9 m, so y″ ₁ t = 1.4 m.

In this case, for example, the steering override threshold Td1 during normal ACCS operation is t
1/2 of the imaginary lateral displacement reaching the permissible lateral position 1e ₁ after seconds, ie y′ ₁ t=(yt+
β)/2=0.7 m, and the steering override threshold Te1 at the time of ACCS malfunction is set to the hypothetical lateral displacement y corresponding to the allowable lateral position _1e1 after t seconds.
″ ₁ The steering torque is set so that t=yt+β=1.4m.

In the case of reverse steering, the imaginary lateral displacement y″ ₂ t=yt−β when it is assumed that the allowable lateral position 1e ₂ that does not deviate from the right lane marking 5c from the current position after t seconds is reached. Then, since β=3.5/2-1.7/2=0.9m, y″ ₂ t=-0.4m,
In this case, the steering override threshold value Td2 during normal ACCS operation is 1/2 of the imaginary lateral displacement reaching the permissible lateral position _1e2 after t seconds, that is, y' ₂ t=(yt-β)/2=
The steering torque is set to −0.2 m, and the steering override threshold Te2 at the time of ACCS malfunction is set to the virtual lateral displacement y″ ₂ t= which corresponds to the allowable lateral position _1e2 after t seconds
The steering torque is set such that yt-β=-0.4m.

In this setting example, the allowable lateral position 1e ₁ where the vehicle 1 does not deviate from the left and right lane markings 5s and 5c.
, 1e ₂ after t seconds, the steering override thresholds T1e and T2e are set based on the steering torque that gives the virtual lateral displacements y″ ₁ t and y″ ₂ t, which are reached after t seconds. It is possible to prevent oversteering while maintaining inner running.

(Flow when ACCS malfunctions)
Next, the flow when the ACCS malfunctions will be described with reference to FIG.

(1) Driving by in-lane partially automated driving system (PADS driving)
When PADS running is selected by the driver's operation, ACCS and LKAS are activated after a system check, and the fact that PADS running is displayed in the instrument panel (step 100). In PADS driving, ACCS and LKAS are interlocked to maintain a single lane at a target speed (cruise set speed) for constant speed driving, or maintain a predetermined inter-vehicle distance for follow-up driving. In this case, the in-lane target route is set by a predetermined offset distance or the like from the lane marking in the center of the lane (driving lane) or either left or right.

(2) Determination of ACCS malfunction While the PADS (ACCS/LKAS) is running, the component parts including the external sensor 21, the internal sensor 22, and the actuator group are constantly monitored for failures and abnormalities, and the malfunction of the ACC is determined. is performed (step 101).

(3) ACC function stop When PADS (ACCS/LKAS) is running, the ACC may stop functioning, such as disconnection of the forward detection millimeter wave radar 211 constituting the external sensor 21 or failure of the hydraulic system of the ESP/ABS controller 33.
If a component malfunction of S is detected, the immediate ACC function is deactivated (step 102) and an ACC malfunction flag is raised (step 103).

(4) Change of steering override threshold At the same time, the steering override threshold is changed to the steering override threshold during normal operation (forward direction T
1d, reverse direction T2d) to steering override thresholds (forward direction T1e, reverse direction T2e) at the time of malfunction (step 113). That is, the lateral movement distance yt
and a value obtained by converting the steering angle calculated from the motion characteristics of the vehicle into a steering torque is calculated, and a steering override threshold value (forward direction T1e, reverse direction T2e) at the time of malfunction is set.

(5) Notification of ACC malfunction and steering takeover At the same time, ACC
The driver is notified of the occurrence of the malfunction and of the steering takeover (LKAS is deactivated via degeneration control) (step 104). At the same time, counting of a predetermined time (for example, 4 seconds) until transition to LKA degeneration control is started.

(6) Judgment of Manual Steering At the same time, the presence or absence of manual steering 34 is judged by the torque sensor attached to the EPS controller 31 (step 105).

(7) Determination of Steering Direction If it is determined that there is manual steering from the detected value of the torque sensor attached to the EPS controller 31, the steering direction of the manual steering 34 is determined (step 106).

Determination of the steering direction is made with respect to the steering torque value calculated in step 113. When the steering torque is applied in the direction of increasing the steering torque, it is determined as forward steering. It is determined that the steering is reversed.

(8) Override Determination It is determined whether or not the steering torque of the manual steering 34 exceeds the override threshold.
(8-1) Determination of Forward Steering Override If the steering direction is determined to be forward steering, the steering torque is forward steering override threshold value T.
1e (step 107).
i) If steering torque>forward steering override threshold value T1e, it is determined that an override has occurred, and the steering is immediately overridden to switch to manual driving.
ii) If steering torque < forward steering override threshold value T1e, no override;
LKA running is continued.

(8-2) Determination of Reverse Steering Override If the steering direction is determined to be reverse steering, the steering torque is set to the reverse steering override threshold value T.
2e (step 108).
i) If steering torque>reverse steering override threshold value T2e, it is determined that there is an override, and the vehicle is immediately overridden and manually driven.
ii) if steering torque<reverse steering override threshold T2e, no override;
LKA running is continued.

(9) Determining Elapsed Time of Taking Over If the LKA running is continued, the predetermined time (4 seconds) after the steering takeover notification is issued in step 104 is continued (step 109), and the predetermined time (4 seconds) is counted. ), the LKAS degeneration control is started (step 110).

(10) LKAS degeneracy control end/function stop/steering takeover When the LKAS degeneracy control for gradually decreasing the steering torque command value input to the EPS controller 31 to 0 (Nm) at a predetermined slope ends, the LKA function is terminated. , the steering is handed over to the driver (step 111), and the steering is completely shifted to manual steering (step 112).

By changing the override threshold value as described above, it is possible to basically prevent overriding due to oversteering when the ACC function fails.
At 108), if manual steering is greater than or equal to the override threshold, the LKA function will be overridden with manual steering.

Therefore, when changing the override threshold at the time of ACC malfunction (step 103), the steering torque or steering angle set according to the vehicle speed (inversely proportional to the vehicle speed/decreased as the vehicle speed increases) in the EPS controller 31 By setting the upper limit of , to a lower value than during normal operation, it is possible to maintain in-lane driving even when overridden by manual steering.

Further, when changing the override threshold value at the time of ACC malfunction (step 103), by changing the steering gain of the manual steering to a smaller value in the EPS controller 31,
Even when overridden by manual steering, the steering amount can be partially reflected in the steering torque.

(action and effect)
As described in detail above, the vehicle cruise control device according to the present invention, when the ACCS malfunctions,
While the driver is notified of the suspension of the ACC function and the LKA function and the takeover of the longitudinal control and the lateral control, and the degeneration control of the LKA function is performed, the steering override threshold is changed to a value larger than that during normal operation. Therefore, when an excessive steering torque that may lead to lane departure is applied by the driver's steering wheel operation, the override state does not occur and the LKA control is continued, so that the in-lane running is maintained. , the override due to oversteering and the resulting lane departure can be prevented.

For example, if a malfunction occurs in the ACCS while the in-lane partially automated driving function is operating and the driver applies corrective steering such as turning the steering wheel further during the LKA degeneration control, the steering override threshold is set large. Therefore, lane departure can be prevented without overriding. Furthermore, since there is no steering override, it is possible to prevent repetition of corrective steering for steering.

In addition, the steering override threshold applied when the ACCS 9 function fails is maintained from the notification of the function stop and the steering takeover until the end of the LKA degeneration control, so that the steering assist by the LKA function is partially acting. Steering can be gradually taken over in this state, which is advantageous for smooth steering takeover.

In addition, the steering override threshold when the ACC function is normal differs depending on whether the steering direction is forward steering or reverse steering with respect to the steering direction at the time of steering intervention. Also, since the steering direction at the time of steering intervention differs depending on whether the steering is forward or reverse, there is an advantage that oversteering can be effectively prevented according to the running state of the vehicle when the ACC function fails. There is

In LKAS, the vehicle is steered so that it runs in the center of the lane. In the case of steering, since the surplus space is relatively small, oversteering can be effectively prevented by applying an override threshold that prioritizes in-lane travel.

The override threshold at the time of ACC malfunction is set in the range of 50% to 100%, preferably 90% to 100%, of the maximum lateral displacement that does not deviate from the driving lane, and the override threshold at the time of normal ACC function is set to the ACC. It is set in a range smaller than the override threshold at the time of malfunction, for example 50% or less, preferably in a range of 40% to 50%. In particular, it is preferable that the override threshold in the above-described reverse steering with relatively little extra space is set based on the maximum lateral displacement that does not deviate from the driving lane.

In the above embodiment, the steering override threshold is set based on the steering torque, but it can also be set based on the steering angle.

Although several embodiments of the present invention have been described above, it should be noted that the present invention is not limited to the above-described embodiments, and that various modifications and changes are possible based on the technical idea of the present invention. I will add.

1 vehicle (own vehicle)
5, 5c, 5d, 5s Sectional line 10 Automatic operation controller 11 Environmental state estimation unit 12 Route generation unit 13 Vehicle control unit 14 ACC controller 15 LKA controller 21 External sensor 22 Internal sensor 31 EPS controller 32 Engine controller 33 ESP/ABS controller 34 Manual steering (handle)
41 steering mechanism 42 engine 43 brake 51, 52 lanes

Claims (6)

an environmental state estimating unit including a surrounding recognition function for recognizing the vehicle's driving lane and other vehicles traveling in the driving lane and a function for acquiring the vehicle's motion state;
a route generation unit that generates a target route based on information acquired by the environmental state estimation unit;
a vehicle control unit that performs speed control and steering control to cause the vehicle to follow the target route;
A vehicle travel control device comprising:
an ACC function that performs constant speed driving according to the target vehicle speed when there is no preceding other vehicle in the lane in which the vehicle is traveling, and performs follow-up driving while maintaining a predetermined inter-vehicle distance when there is another preceding vehicle;
an LKA function that maintains traveling within the own vehicle traveling lane by follow-up control to the target route;
a steering override function that stops the LKA function by a driver's steering intervention;
a function of notifying the driver of the suspension of the LKA function and the steering takeover when the ACC function fails, and performing degeneration control of the LKA function;
in those having
The steering torque or steering angle override threshold that serves as a criterion for steering intervention to stop the LKA function includes an override threshold for normal operation of the ACC function and an override threshold for failure of the ACC function. ,
The override threshold when the ACC function is normal differs between forward steering and reverse steering with respect to the steering direction at the time of the steering intervention, and the override threshold when the ACC function fails is also: A running control device for a vehicle, wherein the steering direction at the time of steering intervention is different between forward steering and reverse steering. The forward steering override threshold when the ACC function is normal is set to a value larger than the reverse steering override threshold when the ACC function is normal, and the forward steering override threshold when the ACC function is malfunctioning is set to a value when the ACC function is malfunctioning. 2. The vehicle running control system according to claim 1, wherein the value is set to be larger than the reverse steering override threshold. The override threshold for forward steering when the ACC function is malfunctioning is set to a value larger than the forward steering override threshold when the ACC function is normal, and the override threshold for reverse steering when the ACC function is malfunctioning is set to a value greater than the forward steering override threshold when the ACC function is normal. 3. The running control system for a vehicle according to claim 2, wherein the value is set to a value larger than the reverse steering override threshold value at time. The override threshold at the time of ACC malfunction is set within a range of 50% to 100% of the maximum lateral displacement that does not deviate from the driving lane, and the override threshold at the time of normal ACC function is the maximum that does not deviate from the driving lane. 4. The running control device for a vehicle according to claim 1, wherein the lateral displacement is set within a range of 50% or less of the lateral displacement. The vehicle running control according to any one of claims 1 to 4, wherein the override threshold at the time of the ACC malfunction is set to a value corresponding to a maximum lateral displacement that does not deviate from the driving lane. Device. 6. The vehicle control system according to any one of claims 1 to 5, further comprising a function of lowering an upper limit value of steering torque or steering angle that is set according to vehicle speed when said override threshold value for when said ACC function fails is set. 1. The vehicle travel control device according to claim 1.

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