JP7000765B2 - Vehicle driving control device - Google Patents

Description

The present invention relates to a vehicle travel control device, and more particularly to a steering override function in a partially automatic travel system in the lane.

Various technologies aimed at reducing the burden on the driver and supporting safe driving, for example, an inter-vehicle distance control system (AdaptiveCruiseControlSystem: ACCS), a lane keeping assistance system (LKAS), and the like have been put into practical use. Furthermore, the practical application and international standardization of the "Partially Automated In-lane Driving System (PADS)" based on these are being promoted.

Such a driving control system has an override function that switches to manual driving by forced intervention of the driver during operation. For example, Patent Document 1 includes a control gain setting means for variably setting a control gain when performing steering control based on a steering target control amount, and a value of a control gain when a driver intervenes in a driving operation is not set. A driving control device is disclosed in which the value is set smaller than the value at the time of intervention and the value of the control gain at the time of turning the vehicle at the time of driving operation intervention is set larger than the value at the time of non-turning of the vehicle. ..

Japanese Unexamined Patent Publication No. 2016-97827

By the way, as shown in FIG. 4, when a functional failure occurs in the ACC system due to a device failure or abnormality during PADS operation (61), the ACC function is stopped at the same time as the failure occurs, and the ACC function is stopped. The driver is notified of the steering takeover request for stopping the LKA function (62), and the mode is set to shift to the LKA degenerate control mode. A few seconds after the notification, the LKA degenerate control starts (63), the LKA degenerate control ends, and the steering is handed over to the driver (64).

In such a system, for example, in order to follow the route to 51c near the center of the lane by the LKA function, if a functional failure occurs in the ACC system during automatic steering on either the left or right side, the LKA function is stopped before the LKA function is stopped. Since the degenerate control mode is entered, if the driver applies corrective steering such as turning the steering wheel during LKA degenerate control, excessive forward steering may be performed.

Furthermore, there is a risk that the driver who is in a hurry to notify the suspension / takeover request will perform excessive steering (steering override). In addition, there is a risk of repeating excessive steering override and correction steering for steering.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vehicle traveling control device capable of preventing excessive steering override in the process of shifting to LKA degeneracy control at the time of ACC function failure. To do.

In order to solve the above problems, the present invention
An environmental state estimation unit including a surrounding recognition function for recognizing the own vehicle driving lane and other vehicles traveling in the driving lane and a function for acquiring the own vehicle motion state, and
A route generation unit that generates a target route based on the information acquired by the environmental state estimation unit, and a route generation unit.
A vehicle control unit that performs speed control and steering control so that the vehicle follows the target path.
It is a running control device of a vehicle equipped with
If there is no other vehicle in front of the vehicle in the driving lane, the vehicle will run at a constant speed according to the target vehicle speed, and if there is another vehicle in front, the ACC function will maintain the specified inter-vehicle distance and follow the vehicle.
The LKA function that maintains driving in the vehicle's driving lane by controlling the follow-up to the target route, and
A steering override function that stops the LKA function by the driver's steering intervention, and a steering override function.
When the ACC function fails, the driver is notified of the stop and steering takeover of the LKA function, and the degeneracy control of the LKA function is performed.
In those with
It has a function to change the overriding threshold value of the steering torque or the steering angle, which is the criterion for determining the steering intervention for stopping the LKA function, to a value larger than that in the normal operation of the ACC function when the ACC function fails. It is characterized by.

According to the vehicle travel control device according to the present invention, the steering override threshold value is changed to a value larger than that in normal operation while the function stop and steering takeover are notified when the ACC function is lost and the degeneration control of the LKA function is performed. Therefore, it is possible to prevent the driver from overriding due to over-steering and the repeated lane deviation and correction steering caused by the over-steering, which is advantageous for smooth steering takeover.

It is a schematic diagram which shows the traveling control system of a vehicle. It is a schematic plan view which shows the outside world sensor group of a vehicle. It is a block diagram which shows the traveling control system of a vehicle. It is a schematic plan view which shows the LKA degeneracy control at the time of ACC function failure. It is a schematic plan view which shows the example of the over-steering prevention control at the time of ACC function failure. It is a schematic plan view which shows the other example of the over-steering prevention control at the time of ACC function failure. It is a flowchart which shows the over-steering prevention control at the time of ACC function failure.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In FIG. 1, in the vehicle 1 provided with the travel control system according to the present invention, in addition to general automobile components such as an engine and a vehicle body, the vehicle side performs recognition, judgment, and operation that have been conventionally performed by a driver. In addition, an outside sensor 21 for detecting the vehicle surrounding environment, an inside sensor 22 for detecting vehicle information, a controller / actuator group for speed control and steering control, an ACC controller 14 for inter-vehicle distance control, and lane keeping support control. It is provided with an LKA controller 15 for controlling the LKA controller 15 and an automatic operation controller 10 for controlling them and performing route tracking control.

The 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) constitutes a stability control system (vehicle behavior stabilization control system) including ABS (anti-lock braking system).

The outside world sensor 21 uses image data and point group data as image data and point group data of the division lines 5s and 5c on the road defining the own lane 51 and the adjacent lane 52, and the presence and relative distance of other vehicles, obstacles, people, etc. around the own vehicle. It comprises a plurality of detection means for inputting to the automatic operation controller 10.

For example, as shown in FIG. 2, the vehicle 1 has a millimeter wave radar (211) and a camera (212) as front detection means 211 and 212, and LIDAR (laser image detection) as front side detection means 213 and rear side detection means 214. / Distance measurement), equipped with a camera (back camera) as a rear detection means 215, covering 360 degrees around the own vehicle, the position and distance of vehicles and obstacles within a predetermined distance in the front-back and left-right directions of the own vehicle, and the position of the dividing line. Is enabled to be detected.

The internal world sensor 22 is composed of a plurality of detection means such as a vehicle speed sensor, a yaw rate sensor, and an acceleration sensor that measure physical quantities indicating the motion state of the vehicle, and as shown in FIG. 3, each measured value is an automatic driving controller 10. , ACC controller 14, LKA controller 15, and EPS controller 31.

The automatic operation 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 a function as described below, that is, a ROM that stores a program and data. It is composed of a CPU that performs arithmetic processing, a RAM that reads the program and data and stores dynamic data and arithmetic processing results, an input / output interface, and the like.

The environmental state estimation unit 11 acquires the absolute position of the own vehicle by using the positioning means 24 such as GPS, and based on the external world data such as the image data and the point cloud data acquired by the external world sensor 21, the own lane 51 and the adjacent vehicle. The division line position of the lane 52, the position of another vehicle, and the speed are estimated. In addition, the motion state of the own vehicle is acquired from the inside world data measured by the inside world sensor 22.

The route generation unit 12 generates a target route from the own vehicle position estimated by the environmental state estimation unit 11 to the arrival target. Further, referring to the map information 23, based on the division line position of the adjacent lane estimated by the environmental condition estimation unit 11, the position and speed of another vehicle, and the motion state of the own vehicle, the arrival target point from the own vehicle position in the lane change is reached. 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 a speed command for constant speed travel or inter-vehicle distance maintenance / follow-up travel to the ACC controller 14. Then, the steering angle command for following the route is transmitted to the EPS controller 31 via the LKA controller 15.

The vehicle speed is also input to the EPS controller 31 and the ACC controller 14. Since the steering torque changes depending on the vehicle speed, the EPS controller 31 transmits a torque command to the steering mechanism 41 with reference to the steering angle-steering torque map for each vehicle speed. By controlling the engine 42, the brake 43, and the steering mechanism 41 by the engine controller 32, the ESP / ABS controller 33, and the EPS controller 31, the vertical and lateral movements of the vehicle 1 are controlled.

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

Partially automatic driving in the lane (PADS driving) can be executed in a state where the ACC controller 14 constituting the ACCS and the LKA controller 15 constituting the LKAS are both operating together with the automatic driving controller 10.

Simultaneously with the operation of the partially automatic driving system in the lane, the automatic driving controller 10 (route generation unit 12) obtains external information (lane, own vehicle position, own vehicle driving lane, and own vehicle driving lane) acquired by the environmental state estimation unit 11 through the external world sensor 21. The target route and the target vehicle speed in a single lane are generated based on the position and speed of another vehicle traveling in the adjacent lane and the internal information (vehicle speed, yaw rate, acceleration) acquired by the internal world sensor 22.

The automatic driving controller 10 (vehicle control unit 13) determines the vehicle by the position of the own vehicle and the kinetic characteristics of the own 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 generated by the motion and the lateral acceleration (d ² y / dt ² ), the speed, attitude, and lateral displacement of the vehicle after Δt seconds are estimated, and the steering angle command so that the lateral displacement becomes yy after Δt seconds. Is given to the EPS controller 31 via the LKA controller 15, and a speed command is given to the ACC controller 14 so that the speed becomes Vt after Δt seconds.

During the partially automatic driving in the lane, the outside world sensor 21 recognizes the preceding vehicle in front of the own lane and the lane dividing line 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, LKA controller 15, EPS controller 31, engine controller 32, and ESP / ABS controller 33 operate independently of automatic steering, but the operation of the partially automatic driving function (PADS) in the lane. Inside, it can be operated even by inputting a command from the automatic operation controller 10.

Upon receiving the deceleration command from the ACC controller 14, the ESP / ABS controller 33 issues a hydraulic pressure command to the actuator and controls the braking force of the brake 43 to control the vehicle speed. Further, the engine controller 32 that receives the acceleration / deceleration command from the ACC controller 14 gives a torque command to the engine 42 by controlling the actuator output (throttle opening), and controls the vehicle speed by controlling the driving force. ..

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

That is, when there is no preceding vehicle, the vehicle runs at a constant speed with the cruise control set speed as the target vehicle speed, and when it catches up with the preceding vehicle (when the preceding vehicle speed is less than or equal to the cruise control set speed), it matches the preceding vehicle speed. , Follows the preceding vehicle while maintaining the inter-vehicle distance according to the set time gap (inter-vehicle time = inter-vehicle distance / own vehicle speed).

The LKA function (LKAS) detects the lane division line and the own vehicle position by the environmental state estimation unit 11 of the automatic driving controller 10 based on the image data acquired by the outside world sensor 21 (cameras 212 and 215), and moves to the center of the lane. 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 issues a torque command to the actuator (EPS motor) with reference to the vehicle speed-steering angle-steering torque map, and the steering mechanism 41 targets it. Gives the front wheel steering angle.

The partially automatic driving function (PADS) in the lane provides vertical control (speed control, inter-vehicle distance control) by the ACC controller 14 and lateral control (steering control, lane keeping driving control) by the LKA controller 15 as described above. It is carried out by combining.

(Override function)
Both the vertical control system (ACCS) and the horizontal control system (LKAS) can be overridden by the driver while the partially automatic driving function (PADS) in the lane is operating.

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

The lateral control system (LKAS) is overridden when the steering torque by the driver's manual steering 34 is equal to or greater than the override threshold value. The override threshold value due to this steering intervention is set according to the steering characteristics and the running state of the vehicle.

Steering override is when the steering torque is applied by steering to determine that the driver has steered with the intention of changing course or avoiding obstacles, or has steered (reverse steering) with the intention contrary to LKA control. , LKA control is stopped, and the driver shifts to driving by manual steering.

By the way, as shown in FIG. 4, when the ACCS function failure occurs due to a failure of the forward detection millimeter wave radar or an ESP / ABS abnormality while the partial automatic driving function (PADS) in the lane is operating ( 61), the ACC function is stopped at the same time as the failure occurs, the LKAS shifts to the degenerate control mode, and the driver is notified of the LKA function stop and the steering takeover request (takeover request) (62), for a few seconds (for example, 4). After a lapse of seconds), the LKA degeneracy control is started (63), and when the steering torque reaches 0 (Nm), the LKA function is stopped and the driver takes over the steering (64).

The LKA degeneracy control is set for the purpose of gradually reducing the steering torque command value input to the EPS controller 31 to 0 (Nm) with a predetermined inclination so that a smooth transition to manual steering can be achieved.

As described above, if the ACCS function fails while the partially automatic driving function in the lane is operating, the ACC function and the LKA function are stopped, and the vertical control and horizontal control by them are taken over by the driver. However, at that time, as already mentioned, there is a risk of excessive steering (steering override) of the driver in a hurry due to the notification of the suspension / takeover request.

(Oversteering prevention function when the ACCS function fails)
Therefore, in the automatic driving controller 10 according to the present invention, the ACCS function fails during the operation of the partially automatic driving function in the lane, and the ACC function and the LKA function are stopped, and the driver of the vertical control and the horizontal control is notified. From the partial automatic driving function stop in the lane (ACC function stop / LKA function stop notification) to the LKA function stop (for example, 4 seconds after the notification-LKA reduction control start-LKA reduction control end) Has an oversteering prevention function that changes the steering override threshold value to a value larger than that during normal operation.

By making the steering override threshold value larger than that during normal operation when the ACCS function fails, the driver's manual steering 34 does not cause an override state even when an excessive steering torque is input to the EPS controller 31, and LKA control is performed. Can be continued and the vehicle can be maintained in the lane.

(Steering override threshold during normal operation)
The steering override threshold during normal ACCS operation is based on the vehicle speed V, the lateral acceleration limit value (for example, 1 m / s ² ), and the lateral movement distance yt for reaching the lane center position (1a) from the current position after t seconds. , The value obtained by converting the steering angle calculated from the virtual lateral displacement y't (= yt + α) and the motion characteristics of the vehicle into steering torque (vehicle speed-steering angle-steering torque calculated from the steering torque map) is set as the override threshold T1d. Will be done.

Specifically, it corresponds to a steering angle such that the virtual lateral displacement y't for reaching the virtual lateral position (1d) after t seconds is yt + α (where α is a constant determined based on the vehicle speed). The steering torque is set to the forward steering override threshold T1d.

In the case of reverse steering, the steering angle calculated from the target lateral movement distance yy for reaching the target position (1a) after t seconds and the motion characteristics of the vehicle is converted into steering torque (steering torque target value). Therefore, the value T2d, which is applied in the direction of reducing the steering torque and can be determined not to be minute (determined by the steering angle, steering angular velocity, etc.), is set. Since the reverse steering is regarded as an indication of the driver's intention to release the LKA control, it is overridden when it is detected as the reverse steering.

For example, assume that a vehicle with a vehicle width of 1.7 m is LKAS traveling 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 end of the lane 51 (it is in a slightly extreme position for easy understanding), the center G in the lateral direction of the vehicle is the right lane division. It is located near 0.9m from line 5c, and LKAS sets the position near 51c in the center of the lane by left automatic steering, that is, near 1.75m from right lane dividing line 5c, so the lateral displacement after t seconds is 1.75-. Assuming 0.9 = 0.85m and α = 0.43m, the steering torque corresponding to the steering angle such that the lateral displacement after t seconds is 1.28m (0.85 + 0.43) is forward steering during normal operation. It is set as the override threshold T1d.

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

(Steering override threshold when function fails)
A value obtained by adding a steering torque (vehicle speed-steering angle-steering torque map and vehicle motion characteristics) so that the lateral movement distance due to the driver's additional steering becomes a predetermined value or more with respect to the forward steering override threshold value T1d during normal ACCS operation. Set in consideration). If the steering torque is such that the lateral movement distance due to the driver's additional steering is less than the predetermined value, it is not overridden.

Specifically, the virtual lateral position (for example, 1 m / s 2) after t seconds is based on the vehicle speed V, the lateral acceleration limit value (for example, 1 m / s ² ), and the lateral movement distance yt for reaching the lane center position (1a) from the current position. The value obtained by converting the steering angle calculated from the motion characteristics of the vehicle into the steering torque is the virtual lateral displacement y ″ ₁ t (= yt + β, where β> α, β = 2α in the illustrated example) to reach 1e ₁ ). It is set as the forward steering override threshold T1e.

For example, as described above, it is assumed that a vehicle having a vehicle width of 1.7 m is traveling in LKAS on a highway having a lane width of 3.5 m. As shown in FIG. 5, assuming that the vehicle 1 is traveling near the right end of the lane, the lateral movement distance yt for reaching the center position (1a) of the lane 51 from the current position after t seconds is 1.75. -0.9 = 0.85m, but when the function fails, β = 0.85m and the steering angle is set so that the virtual lateral displacement after t seconds is 1.75m (= 0.9 + 0.85). The corresponding steering torque is set as the forward steering override threshold T1e. Even if the actual lateral displacement is set to 1.75 m, it is possible to maintain driving in the lane.

On the other hand, the reverse steering override threshold T2e approximates the virtual lateral displacement corresponding to the reverse steering override threshold T2d during normal operation to the lateral movement distance yt for reaching the lane center position (1a) from the current position. Based on this, the virtual lateral displacement for reaching the virtual lateral position (1e ₂ ) after t seconds is y ″ ₂ t (= yt−γ, where γ is larger than the lateral displacement corresponding to the steering torque X ′ Nm. In the example, a value obtained by converting the steering angle calculated from γ = α) and the motion characteristics of the vehicle into steering torque is set as the reverse steering override threshold T2e.

In this case, as shown in FIG. 5, the steering torque corresponding to the steering angle such that γ = 0.43 m and the lateral displacement after t seconds is 0.42 m (= 0.85-0.43) is obtained. It is set as the reverse steering override threshold T2e. As is clear from FIG. 5, it is possible to maintain driving in the lane even in the virtual lateral position (1e ₂ ).

(Other setting examples of steering override threshold value when function fails)
FIG. 6 shows another setting example of the steering override threshold value when the ACCS function fails. In this example, the vehicle 1 having a vehicle width of 1.7 m runs in LKAS near the center of a highway having a lane width of 3.5 m. It is assumed that the case is.

First, when the vehicle 1 is traveling 0.5 m to the right in the traveling direction from the center 51c of the lane, the lateral movement distance yt (= 0.5 m) for reaching the center 51c of the lane from the current position after t seconds, t. If it is assumed that the allowable lateral position 1e ₁ that does not deviate from the left lane dividing line 5s from the current position is reached after a second, the virtual lateral displacement y ″ ₁ t = yt + β is assumed to be β = 3.5 / 2-1.7. Since / 2 = 0.9 m, y ″ ₁ t = 1.4 m.

In this case, for example, the steering override threshold Td1 during normal ACCS operation is _1/2 of the virtual lateral displacement that reaches the allowable lateral position 1e1 after t seconds, that is, _y'1 t = (yt + β) / 2 = 0. The steering torque is set to 7 m, and the steering override threshold value Te1 at the time of ACCS function failure becomes the virtual lateral displacement y ″ ₁ t = yt + β = _1.4 m corresponding to the allowable lateral position 1e1 after t seconds. It is set to such a steering torque.

The same applies to the case of reverse steering, and the virtual lateral displacement y ″ ₂ t = yt-β assuming that the allowable lateral position 1e ₂ that does not deviate from the right lane dividing line 5c from the current position is reached after t seconds. Then, since β = 3.5 / 2-1.7 / 2 = 0.9 m, y ″ ₂ t = −0.4 m. In this case, the steering override threshold value Td2 during normal ACCS operation is t seconds. The steering torque is set to 1/2 of the virtual lateral displacement that later reaches the allowable lateral position 1e ₂ , that is, y'2 _t = (yt-β) /2=-0.2 m, and the ACCS function fails. The steering override threshold value Te2 at time is set to a steering torque such that the virtual lateral displacement y ″ ₂ t = yt-β = −0.4 m corresponding to the allowable lateral position 1e ₂ after t seconds.

In this setting example, the vehicle 1 is steered so as to have a virtual lateral displacement y ″ ₁ t, y ″ ₂ t that reaches the allowable lateral positions 1e ₁ and 1e ₂ that do not deviate from the left and right lane dividing lines 5s and 5c after t seconds. Since the steering override thresholds T1e and T2e are set based on the torque when the ACCS function fails, it is possible to prevent over-steering while maintaining driving in the lane.

(Flow when ACCS function fails)
Next, the flow when the ACCS function fails will be described with reference to FIG. 7.

(1) Driving by a partially automatic driving system in the lane (PADS driving)
When PADS driving is selected by the driver's operation, ACCS and LKAS are started after a system check, and it is displayed in the instrument panel or the like that PADS driving is in progress (step 100). In PADS travel, ACCS and LKAS work together to maintain a single lane at a target speed (cruise set speed) for constant speed travel, or to maintain a predetermined inter-vehicle distance for follow-up travel. In this case, the target route in the lane is set by a predetermined offset distance from the center of the lane (traveling lane) or the lane dividing line on either the left or right side.

(2) ACCS function failure determination While PADS (ACCS / LKAS) is running, the presence or absence of failures or abnormalities in components including the external sensor 21, internal sensor 22, and actuator group is constantly monitored, and the ACC function failure is determined. Is performed (step 101).

(3) ACC function stop While the PADS (ACCS / LKAS) is running, the parts that make up the ACCS, such as the disconnection of the millimeter-wave radar 211 for forward detection that constitutes the external sensor 21, and the failure of the hydraulic system of the ESP / ABS controller 33. If a function failure is detected, the ACC function is immediately stopped (step 102), and the ACC function failure flag is set (step 103).

(4) Change of steering override threshold At the same time, the steering override threshold changes from the steering override threshold during normal operation (forward T1d, reverse T2d) to the steering override threshold during functional failure (forward T1e, reverse T2e). It is changed (step 113). That is, a value obtained by converting the steering angle calculated from the lateral movement distance yt and the motion characteristics of the vehicle at this point into steering torque is calculated, and the steering override threshold value (forward direction T1e, reverse direction T2e) at the time of functional failure is set. Will be done.

(5) Notification of ACC function failure / steering takeover At the same time, the driver is notified of the occurrence of ACC function failure and steering takeover (LKAS is stopped via degeneracy control) by the display and voice in the head-up display and instrument panel. Is notified (step 104). At the same time, counting for a predetermined time (for example, 4 seconds) until the transition to the LKA degeneracy control is started.

(6) Determination of presence / absence of manual steering At the same time, the presence / absence of manual steering 34 is determined by the torque sensor attached to the EPS controller 31 (step 105).

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

The steering direction is determined to be forward steering when applied in the direction of increasing the steering torque with respect to the steering torque value calculated in step 113, and when applied in the direction of decreasing the steering torque. It is determined to be reverse steering.

(8) Override determination It is determined whether or not the steering torque of the manual steering 34 exceeds the override threshold value.
(8-1) Forward steering override determination When the steering direction determination determines forward steering, the steering torque is compared with the forward steering override threshold value T1e (step 107).
i) If steering torque> forward steering override threshold value T1e, it is determined that the vehicle is overridden, and the vehicle is immediately overridden and manually driven.
ii) If the steering torque <forward steering override threshold value T1e, the LKA running is continued without overriding.

(8-2) Reverse steering override determination When the steering direction determination determines reverse steering, the steering torque is compared with the reverse steering override threshold value T2e (step 108).
i) If steering torque> reverse steering override threshold value T2e, it is determined that the vehicle is overridden, and the vehicle is immediately overridden and manually driven.
ii) If the steering torque <reverse steering override threshold value T2e, the LKA running is continued without overriding.

(9) Determining the elapsed time for taking over When the LKA running is continued, the counting for the predetermined time (4 seconds) after issuing the steering takeover notification in step 104 is continued (step 109), and the predetermined time (4 seconds) is continued. ) Has elapsed, the LKAS degeneracy control is started (step 110).

(10) LKAS degeneration control end / function stop / steering takeover When the LKAS degeneration control that gradually reduces the steering torque command value input to the EPS controller 31 to 0 (Nm) with a predetermined inclination ends, the LKA function is stopped. , The steering is handed over to the driver (step 111), and the manual steering is completely shifted (step 112).

By changing the override threshold value as described above, override due to oversteering when the ACC function fails can be basically prevented, but in the above-mentioned override determination (steps 107 and 108), if the manual steering is equal to or higher than the override threshold value, The LKA function will be overridden by manual steering.

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

Further, when the override threshold value is changed (step 103) when the ACC function is lost, the steering gain of the manual steering is changed to a small value in the EPS controller 31, so that the steering is overridden by the manual steering. The amount can also be partially reflected in the steering torque.

(Action and effect)
As described in detail above, the vehicle travel control device according to the present invention is notified to the driver that the ACC function and the LKA function are stopped and the vertical control and the horizontal control are taken over when the ACCS function fails, and the LKA function is provided. Since the steering override threshold is changed to a value larger than that during normal operation while the degeneracy control is performed, the driver's steering wheel operation gives an excessive steering torque that leads to lane deviation. If this happens, the vehicle will not be overridden and the LKA control will be continued, so that driving in the lane will be maintained, and overriding due to oversteering and lane deviation due to the oversteering can be prevented.

For example, even if the ACCS fails during the partial automatic driving function in the lane and the driver performs corrective steering such as turning the steering wheel during LKA degeneracy control, the steering override threshold value is set large. Therefore, it is possible to prevent lane deviation without overriding. Further, since the steering is not overridden, it is possible to prevent the repetition of the correction steering with respect to the steering.

Further, the steering override threshold value applied when the nine functions of the ACCS are lost is maintained from the notification of the stoppage and the steering takeover to the end of the LKA degeneracy control, so that the steering assist by the LKA function is partially acting. Since the steering can be gradually taken over in the state, it is advantageous for smooth steering takeover.

Further, the steering override threshold value when the ACC function is normal differs depending on whether the steering is forward steering or reverse steering with respect to the steering direction at the time of steering intervention, but the steering override threshold value is changed when the ACC function fails as described above. However, since the steering is different depending on the steering direction at the time of steering intervention and the case of reverse steering, there is an advantage that over-steering can be effectively prevented according to the running state of the vehicle when the ACC function is lost. There is.

In LKAS, the vehicle is steered and controlled so as to travel in the center of the driving lane. Therefore, in the case of forward steering with respect to the steering direction at the time of steering intervention, there is a lot of surplus space in the lateral movement direction of the vehicle, whereas the opposite is true. In the case of steering, since the surplus space is relatively small, it is possible to effectively prevent oversteering by applying an override threshold that gives priority to driving in the lane.

The override threshold value when the ACC function fails is set in the range of 50% to 100%, preferably 90% to 100% of the maximum lateral displacement that does not deviate from the traveling lane, and the override threshold value when the ACC function is normal is the ACC. It is set in a range smaller than the override threshold value at the time of functional failure, for example, 50% or less, preferably 40% to 50%. In particular, it is preferable that the override threshold value in the case of reverse steering having a relatively small excess space described above is set based on the maximum lateral displacement that does not deviate from the traveling lane.

Although the above embodiment shows the case where the steering override threshold value is set based on the steering torque, it can also be configured to be set based on the steering angle (steering angle).

Although some embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications and modifications can be made based on the technical idea of the present invention. I will add.

1 Vehicle (own vehicle)
5,5c, 5d, 5s division 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 (steering wheel)
41 Steering mechanism 42 Engine 43 Brake 51, 52 lanes

Claims (5)

An environmental state estimation unit including a surrounding recognition function for recognizing the own vehicle driving lane and other vehicles traveling in the driving lane and a function for acquiring the own vehicle motion state, and
A route generation unit that generates a target route based on the information acquired by the environmental state estimation unit, and a route generation unit.
A vehicle control unit that performs speed control and steering control so that the vehicle follows the target path.
It is a running control device of a vehicle equipped with
If there is no other vehicle in front of the vehicle in the driving lane, the vehicle will run at a constant speed according to the target vehicle speed, and if there is another vehicle in front, the ACC function will maintain the specified inter-vehicle distance and follow the vehicle.
The LKA function that maintains driving in the vehicle's driving lane by controlling the follow-up to the target route, and
A steering override function that stops the LKA function by the driver's steering intervention, and a steering override function.
When the ACC function fails, the driver is notified of the stop and steering takeover of the LKA function, and the degeneracy control of the LKA function is performed.
In those with
It has a function of changing the override threshold value of the steering torque or steering angle, which is the criterion for determining the steering intervention for stopping the LKA function, to a value larger than that during normal operation of the ACC function when the ACC function fails. A vehicle travel control device characterized by. The vehicle travel control device according to claim 1, wherein the override threshold value at the time of failure of the ACC function is maintained from the notification of the stop and steering takeover of the LKA function to the end of the degenerate control. The override threshold value when the ACC function is normal differs between forward steering and reverse steering with respect to the steering direction at the time of steering intervention, and the override threshold value is changed when the ACC function fails. The vehicle travel control device according to claim 1 or 2, wherein the steering is different between the case of forward steering and the case of reverse steering with respect to the steering direction at the time of the steering intervention. The aspect of any one of claims 1 to 3, wherein the override threshold value at the time of failure of the ACC function is set in the range of 50% to 100% of the maximum lateral displacement that does not deviate from the traveling lane. Vehicle travel control device. The invention according to any one of claims 1 to 4, further comprising a function of lowering the upper limit value of the steering torque or the steering angle set according to the vehicle speed when the override threshold value is changed when the ACC function fails. Vehicle driving control device.

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