Drive assisting device

Abstract

To provide a drive assisting device capable of deactivating a traffic lane maintaining function at a time point at which a drive operation to change the traffic lane is started, and then activating again such a function at an appropriate timing.SOLUTION: A drive assisting device includes a processor configured to be able to execute a traffic lane maintaining process for controlling an own vehicle in such a way that the own vehicle runs along a traffic lane. The processor restricts the execution of the traffic lane maintaining process with a trigger such that the turn signal of the own vehicle starts turning on in a situation in which the own vehicle runs through a first traffic lane, and then stops the operation of the turn signal and cancels the restriction for the execution of the traffic lane maintaining process when a determination is made such that the traffic lane change to a second traffic lane adjacent to the first traffic lane completes and when a predetermined cancel condition is satisfied which is for determining as the own vehicle controllable in such a way that the own vehicle runs along the second traffic lane.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a driving assistance device that controls a steering device of a vehicle so that the vehicle travels along a lane. [Background technology]

[0002] A driving assistance device has been proposed that controls the steering device of a vehicle so that the vehicle moves along a lane (see, for example, Patent Document 1 below). The driving assistance device of Patent Document 1 (hereinafter referred to as the "conventional device") analyzes an image (foreground image) obtained by capturing a scene in front of the vehicle and controls the steering device of the vehicle so that the vehicle is positioned near the center of the lane (travel lane) in the width direction (lane keeping function). The conventional device disables the lane keeping function while the driver is performing a driving operation (lane change) to move the vehicle from a first lane in which the vehicle is currently located to a second lane adjacent to the first lane. Specifically, the conventional device disables the lane keeping function when it detects that the turn signal lights of the vehicle have started to operate (flash). After disabling the lane keeping function, conventional devices enable the lane keeping function if, based on a foreground image, they determine that a predetermined condition regarding the positional relationship between the vehicle and a dividing line (the boundary line between the first lane and the second lane) is met (if they determine that the vehicle has crossed the dividing line). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2022-77931 Summary of the Invention

[0004] Generally, when a steering device is automatically controlled by a lane-keeping function, an upper limit on the vehicle's lateral acceleration (lateral acceleration) (upper limit on the steering angle) is set to minimize passenger discomfort. For example, when changing lanes from a first lane to a second lane, if the vehicle's entry angle into the second lane is relatively large, even if automatic steering is performed by the lane-keeping function, the upper limit on the vehicle's lateral acceleration (steering angle) is set (because the vehicle's turning radius cannot be made too small). This means that the vehicle may deviate from the edge of the second lane (the edge opposite the first lane) during the process of correcting the vehicle's position and attitude relative to the second lane so that it travels along the second lane. Furthermore, conventional systems activate the lane-keeping function when a predetermined condition regarding the positional relationship between the lane marking and the vehicle is met, but it is difficult for the driver to recognize when the lane-keeping function is activated.

[0005] One of the objects of the present invention is to provide a driving assistance device that can disable the lane keeping function when a driving operation for changing lanes is initiated, and then re-enable the function at an appropriate timing.

[0006] In order to solve the above problems, the driving assistance device (1) of the present invention comprises: an on-vehicle sensor (20) including sensors (21, 22, 23) for acquiring the position and attitude of the host vehicle relative to the lane in which the host vehicle is traveling, and a sensor (24) for acquiring the vehicle speed of the host vehicle; a processor (10) configured to be able to execute a lane keeping process for controlling the host vehicle so that the host vehicle moves along the lane; Equipped with. The processor restricts the execution of the lane keeping process when the turn signal lights of the vehicle start to operate while the vehicle is traveling in a first lane (L1), and then, when it determines that a lane change to a second lane (L2R, L2L) adjacent to the first lane has been completed and a predetermined release condition for determining that the vehicle can be controlled to proceed along the second lane is met, it stops the operation of the turn signal lights and releases the restriction on the execution of the lane keeping process.

[0007] As in the conventional device described above, if the lane keeping process is resumed upon completion of a lane change from the first lane to the second lane, the host vehicle may deviate from the second lane within a short period of time after the lane keeping process has been resumed. When the processor of the driving assistance device according to the present invention determines that the lane change from the first lane to the second lane has been completed, the processor resumes the lane keeping process if a condition (cancellation condition) for determining that the host vehicle can be controlled to proceed along the second lane is met. This prevents the host vehicle from deviating from the second lane within a short period of time after the lane keeping process has been resumed in the second lane. That is, according to the present invention, the lane keeping process is resumed at an appropriate timing after the lane change is completed. Furthermore, the turn signal lights are automatically deactivated (turned off) upon the satisfaction of the cancellation condition. This allows the driver to recognize that the lane keeping process has been resumed. That is, the driver can recognize that the driving operation (steering) can be somewhat entrusted to the driving assistance device.

[0008] In one aspect of the present invention, there is provided a driving assistance device, When the processor detects, based on information obtained from the onboard sensor, that all wheels of the vehicle have entered the second lane, it determines that the lane change from the first lane to the second lane has been completed.

[0009] This prevents the lane keeping process (driving assistance) from being initiated when the host vehicle is straddling the dividing line that separates the first lane and the second lane.

[0010] In a driving assistance device according to another aspect of the present invention, When the processor determines that the lane change is complete, it assumes that the lane keeping process has been resumed from the current point in time, calculates a predicted trajectory (TR), which is the area that the vehicle is predicted to pass through until a specified condition regarding the position and attitude of the vehicle relative to the second lane is met by executing the lane keeping process, and determines that the release condition has been met if the predicted trajectory is within the second lane.

[0011] According to this, when the cancellation condition is met, the host vehicle is caused to travel along the predicted trajectory, thereby preventing the host vehicle from deviating from the second lane.

[0012] In a driving assistance device according to another aspect of the present invention, After detecting that the turn signal lights have started to operate while the vehicle is traveling in the first lane, the processor stops the operation of the turn signal lights if a cancellation condition for determining that it is difficult to perform the lane keeping process in the second lane is met during the period before determining that the lane change from the first lane to the second lane has been completed.

[0013] According to this, if it is predicted before the lane change is completed that it will be difficult to perform lane keeping processing in the second lane, the driver is suggested (prompted) to abort the lane change.

[0014] In a driving assistance device according to another aspect of the present invention, The processor is configured to determine that the cancellation condition is met when the width of the second lane is equal to or less than a threshold value or when an obstacle is present in the second lane.

[0015] This allows the driver to recognize that the width of the second lane is narrow or that an obstacle exists in the second lane. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a block diagram of a driving assistance device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view showing the attitude of the host vehicle relative to the lane. [Figure 3] FIG. 3 is a plan view showing an example in which the predicted trajectory falls within the second lane. [Figure 4] FIG. 4 is a plan view showing an example in which the predicted trajectory deviates from the second lane. [Figure 5] FIG. 5 is a flowchart of the program. DETAILED DESCRIPTION OF THE INVENTION

[0017] (Summary) As shown in Fig. 1, a driving assistance device 1 (lane keeping device) according to one embodiment of the present invention is applied to a vehicle V0 (hereinafter referred to as "host vehicle") equipped with an automatic driving function. The driving assistance device 1 has an LTA (=Lane Tracing Assist) function that performs lane keeping control to control the host vehicle so that the host vehicle moves along the lane in which the host vehicle is traveling when the automatic driving function is disabled (when the driver is performing driving operations).

[0018] (Specific configuration) The driving assistance device 1 includes an ECU 10, an on-board sensor 20, a drive device 30, a braking device 40, a steering device 50, an alarm device 60, and a direction indicator 70.

[0019] The ECU 10 includes a microcomputer equipped with a CPU 10a, a ROM 10b (flash ROM), a RAM 10c, a timer 10d, etc. The ECU 10 is connected to other ECUs provided in the vehicle via a CAN (Controller Area Network).

[0020] The ECU 10 includes a microcomputer including a CPU 10a, a ROM 10b, a RAM 10c, a timer 10d, etc. The ECU 10 is connected to other ECUs via a CAN (Controller Area Network).

[0021] The on-board sensors 20 include a camera 21, a millimeter wave radar 22, a navigation system 23, a vehicle speed sensor 24, an acceleration sensor 25, and a driving assistance switch 26.

[0022] The camera 21 includes an imaging device and an image analysis device. The imaging device incorporates, for example, a CCD. The imaging device is installed at the front of the host vehicle. The imaging device captures an image of a predetermined area ahead of the host vehicle at a predetermined frame rate to acquire a foreground image PIC. The image analysis device analyzes the foreground image PIC acquired from the imaging device to recognize objects ahead of the host vehicle. For example, the image analysis device recognizes a preceding vehicle and lane marks (markings that separate lanes (driving lanes)). Based on the positions (coordinates) and extension directions of the lane marks in the foreground image PIC, the image analysis device calculates the position (position of the host vehicle in the width direction of the lane L1) and attitude (the angle φ between the fore-and-aft direction of the host vehicle in a plan view ( FIG. 2 ) and the extension direction of the lane L1 (or, on a curved road, the tangent at the current location) of the host vehicle in the lane L1 on which the host vehicle is traveling). The image analysis device provides the calculation results (position information and attitude information) to the ECU 10.

[0023] The millimeter-wave radar 22 includes a transmitter / receiver and a signal processor. The transmitter / receiver emits millimeter-wave radio waves (hereinafter referred to as "millimeter waves") to the surrounding area (forward of the vehicle) of the vehicle and receives millimeter waves (reflected waves) reflected by three-dimensional objects located within the surrounding area. The signal processor acquires various information about each reflection point of the millimeter waves based on physical quantities such as the time from when the transmitter / receiver emits the millimeter waves to when the reflected waves are received, the attenuation level of the reflected waves, and the difference between the frequency of the emitted millimeter waves and the frequency of the received reflected waves. For example, the signal processor calculates the position of each reflection point (the position (direction and distance) relative to the transmitter / receiver). The signal processor also calculates the speed (relative speed) of each reflection point relative to the vehicle. The calculation result (data indicating the distribution of the reflection points (the position and relative speed of each reflection point relative to the vehicle)) is then provided to the ECU 10.

[0024] The navigation system 23 acquires location information indicating the current location (latitude and longitude) of the vehicle based on multiple GPS signals. The navigation system 23 also stores map information indicating a map. Based on the location information and map information, the navigation system 23 acquires information about the road including the lane on which the vehicle is traveling (such as the number of lanes that make up the road and the degree of curves), and provides the information to the ECU 10.

[0025] The vehicle speed sensor 24 includes a rotation speed measurement circuit and a vehicle speed calculation device. The rotation speed measurement circuit includes a pulse generation circuit that outputs a pulse (electrical signal) each time a wheel of the host vehicle rotates by a predetermined angle, and a counter circuit that counts the number of pulses. The vehicle speed calculation device acquires the output value (number of pulses) of the counter circuit at predetermined intervals (each time a unit time elapses) and resets the count value to "0." In this way, the vehicle speed calculation device acquires the number of rotations N of the wheel per unit time. The vehicle speed calculation device acquires the vehicle speed sp0 (absolute value) of the host vehicle by multiplying the number of rotations N by a coefficient k. The vehicle speed calculation device then provides the acquired vehicle speed sp0 to the ECU 10.

[0026] The acceleration sensor 25 includes a piezoelectric element. When the host vehicle accelerates (or decelerates) in the longitudinal direction and / or the width direction, the piezoelectric element deforms in the longitudinal direction (longitudinal direction) and / or the width direction (lateral direction) of the host vehicle, and the output voltage of the piezoelectric element changes in accordance with the deformation. The acceleration sensor 25 acquires the longitudinal and lateral accelerations of the host vehicle based on the output voltage of the piezoelectric element. The acceleration sensor 25 then provides these accelerations to the ECU 10.

[0027] The driving assistance switch 26 includes push-button normally open switches (ACC switch and LTA switch) that are used to request the driving assistance device 1 to execute driving assistance (ACC processing and LTA processing) described below. The ACC switch and LTA switch are configured to alternate between on and off states each time they are pressed. In addition, the ACC switch and LTA switch can be forcibly transitioned to the off state by a command from another ECU.

[0028] The drive unit 30 applies drive force to the drive wheels. The drive unit 30 includes an engine ECU, an internal combustion engine, a transmission, a drive force transmission mechanism that transmits drive force to the wheels, and the like. The engine ECU obtains a target value for drive force from another ECU (ECU 10). The engine ECU controls the throttle valve of the internal combustion engine so that the drive force applied to the drive wheels matches the target value.

[0029] If the vehicle to which the driving assistance device 1 is applied is a hybrid vehicle (HEV), the engine ECU can adjust the driving force of the vehicle generated by either or both of an internal combustion engine and an electric motor as the vehicle drive source. Also, if the vehicle to which the driving assistance device 1 is applied is an electric vehicle (BEV), an electric motor ECU can be used instead of the engine ECU to adjust the driving force of the vehicle generated by an electric motor as the vehicle drive source.

[0030] The braking device 40 applies braking force to the wheels (brake discs). The braking device 40 includes a brake ECU, a brake caliper, etc. The brake caliper includes an actuator that presses brake pads against the brake disc. The brake ECU obtains a target value for the braking force from another ECU. The brake ECU controls the actuator of the brake caliper so that the braking force applied to the wheels matches the target value.

[0031] The steering device 50 adjusts the steering angle of the steered wheels (left front wheel and right front wheel). The steering device 50 includes a steering ECU and a steering mechanism. The steering device 50 further includes an actuator (e.g., an electric motor) that drives the steering mechanism to change the steering angle, and a steering angle sensor that acquires the steering angle (actual steering angle) of the steered wheels. The ECU 10 determines a target value θt of the steering angle θ (actual steering angle) of the steered wheels based on various information acquired from the on-board sensor 20. For example, the ECU 10 determines the target value θt so that the host vehicle moves along the lane. The steering ECU acquires the target value θt from the ECU 10 and controls the actuator so that the actual steering angle output from the steering angle sensor matches the target value θt.

[0032] The notification device 60 includes an image display device and an audio device. The image display device is disposed, for example, on an instrument panel (for example, near a speedometer). The image display device displays an image in accordance with a command received from the ECU 10. The audio device reproduces sound in accordance with a command received from the ECU 10.

[0033] The turn signal device 70 includes an operating lever, a lever sensor, a turn signal light, and a drive circuit (turn signal ECU). The lever sensor includes a first switch and a second switch whose on / off state changes depending on the position of the operating lever. When the operating lever is in the neutral position, the first switch and the second switch are in the off state. When the operating lever is in the first position (right turn indication position), the first switch is in the on state and the second switch is in the off state. When the operating lever is in the second position (left turn indication position), the first switch is in the off state and the second switch is in the on state. The drive circuit flashes the right turn signal light when the first switch is in the on state, and flashes the left turn signal light when the second switch is in the on state. The ECU 10 can also obtain the on / off states of the first switch and the second switch from the drive circuit. The ECU 10 can detect the operating state of the turn signal light of the vehicle based on the on / off states of the first switch and the second switch. The direction indicator 70 also has a function for forcibly returning the operating lever to the neutral position in accordance with a command from the ECU 10 (a device for forcibly turning off the direction indicator light).

[0034] (Activated) When the ACC switch is in the on state, the ECU 10 determines whether or not a preceding vehicle V1 is present, and executes ACC processing to control the drive device 30 and braking device 40 (hereinafter referred to as "drive device, etc.") of the host vehicle based on the determination result, as will be described below. The ACC processing includes a constant speed traveling processing and a following distance maintenance processing.

[0035] [Constant speed driving processing] The ECU 10 determines whether or not a preceding vehicle V1 is present based on information acquired from the on-board sensors 20 (camera 21 and millimeter-wave radar 22). If a preceding vehicle V1 is not present, the ECU 10 controls the drive device and the like so that the vehicle speed sp0 of the host vehicle coincides with a predetermined value spt (for example, the vehicle speed at which the fuel consumption rate is lowest).

[0036] [Maintaining distance between vehicles] When the ECU 10 determines that a preceding vehicle V1 is present, the ECU 10 calculates the inter-vehicle distance D between the preceding vehicle V1 and the subject vehicle and the vehicle speed sp1 of the preceding vehicle V1 based on information acquired from the camera 21 and the millimeter-wave radar 22. The ECU 10 calculates a target distance Dt for the inter-vehicle distance D based on the vehicle speed sp0 of the subject vehicle and the vehicle speed sp1 of the preceding vehicle V1.

[0037] When the vehicle speed sp1 of the preceding vehicle V1 relative to the vehicle speed sp0 of the subject vehicle (relative speed vr = sp1 - sp0) is greater than "0", the inter-vehicle distance D increases. When the inter-vehicle distance D is greater than the target distance Dt, the ECU 10 sets the target value of the acceleration α of the subject vehicle to a predetermined value α1 (>0) so that the vehicle speed sp0 of the subject vehicle is greater than the vehicle speed sp1 of the preceding vehicle V1. Then, the ECU 10 controls the drive system and the like so that the acceleration α (actual measured value) of the subject vehicle matches the predetermined value α1 (acceleration control). As a result, the inter-vehicle distance D decreases and approaches the target distance Dt. Then, when the inter-vehicle distance D matches the target distance Dt, the ECU 10 sets the target value of the acceleration α of the subject vehicle to "0". In other words, the ECU 10 controls the drive system and the like so that the subject vehicle travels at the same vehicle speed as the preceding vehicle V1.

[0038] On the other hand, when the relative speed vr is smaller than "0", the inter-vehicle distance D decreases. When the inter-vehicle distance D is smaller than the target distance Dt, the ECU 10 sets the target value of the acceleration α to a predetermined value α2 (<0) so that the vehicle speed sp0 of the host vehicle becomes smaller than the vehicle speed sp1 of the preceding vehicle V1. Then, the ECU 10 controls the drive device, etc. so that the acceleration α (actual measured value) of the host vehicle matches the predetermined value α2 (<0) (deceleration control). As a result, the inter-vehicle distance D increases and approaches the target distance Dt. Then, when the inter-vehicle distance D matches the target distance Dt, the ECU 10 sets the target value of the acceleration α of the host vehicle to "0".

[0039] A map showing the relationship between the vehicle speeds sp0, sp1 and the target distance Dt or parameters defining an arithmetic expression for calculating the target distance Dt are stored in the ROM 10b. The ECU 10 determines the target distance Dt based on the map or the arithmetic expression.

[0040] [Lane keeping processing] When the ACC switch is in the on state and the LTA switch is in the on state, the ECU 10 executes a lane keeping process (LTA process) that controls the steering device 50 so that the host vehicle travels along the lane L1 (the lane the host vehicle is currently traveling on). Specifically, based on information acquired from the camera 21, the ECU 10 controls the steering device 50 so that the host vehicle is positioned within a predetermined range near the center in the width direction of the lane L1 (for example, a state in which the difference Δd (=|ΔdL-ΔdR|) between the distance ΔdL between the left-side dividing line and a predetermined point on the left side of the host vehicle and the distance ΔdR between the right-side dividing line and a predetermined point on the right side of the host vehicle is equal to or less than a threshold Δdth) and the direction of the host vehicle is approximately parallel to the extension direction of the lane L1 (φ<φth). Here, the ECU 10 controls the steering device 50 (sets the target value θt of the steering angle θ) so that the lateral acceleration of the host vehicle when the host vehicle turns due to the execution of the LTA processing is equal to or less than a predetermined upper limit value. Specifically, the ECU 10 is provided with a map M that defines the relationship between the vehicle speed sp0 and the upper limit value θtmax of the target value θt, and acquires the upper limit value θtmax corresponding to the current vehicle speed sp0 by referring to the map M. Here, the map M is designed so that the upper limit value θtmax decreases as the vehicle speed sp0 increases. In other words, when the vehicle speed sp0 is relatively high, the turning radius of the host vehicle cannot be made very small. Therefore, the host vehicle may deviate from the lane during the process of correcting the position and attitude of the host vehicle relative to the lane due to the execution of the LTA processing (see FIG. 4). Furthermore, even if the vehicle speed sp0 is relatively low, if the vehicle's attitude relative to the lane is significantly out of alignment (if the angle φ is excessively large), the vehicle may deviate from the lane during the process of correcting the vehicle's position and attitude relative to the lane by executing the LTA processing.

[0041] When the ECU 10 detects, based on information acquired from the camera 21 and the navigation system 23, that the host vehicle has deviated from the lane L1 (that is, a part of the host vehicle overlaps a lane mark in a plan view), the ECU 10 terminates execution of the lane keeping process and sets the LTA switch to the OFF state. In this case, in addition to the LTA process, the ECU 10 may terminate execution of the ACC process and set the ACC switch to the OFF state. Next, the ECU 10 causes the notification device 60 to display a predetermined image and play a predetermined sound to prompt the driver to manually perform a driving operation to move the host vehicle toward the center of the lane in the width direction. The driving assistance device 1 may also have a lane departure prevention function that, when it detects that the host vehicle is likely to deviate from the lane, allows the lateral acceleration of the host vehicle to increase somewhat and controls the steering device 50 to pull the host vehicle back toward the center of the lane in the width direction.

[0042] Meanwhile, while executing the LTA process, the ECU 10 monitors the on / off states of the first switch and the second switch of the turn indicator 70. When the ECU 10 detects that the first switch or the second switch of the turn indicator 70 has transitioned from an off state to an on state (that the left or right turn indicator light has started to operate (flash)), the ECU 10 temporarily suspends (limits) the execution of the ACC process and the LTA process. In this state, the ACC switch and the LTA switch remain on, and the ECU 10 can resume the ACC process and the LTA process when the conditions described below are met. In this state, the drive unit 30, the braking unit 40, the steering unit 50, and the like of the host vehicle are controlled according to the driver's driving operations. For example, a driving operation (lane change) to move the host vehicle from lane L1 to lane L2R, which is an adjacent lane to the right of lane L1, or lane L2L, which is an adjacent lane to the left of lane L1, can be executed as intended by the driver without intervention from the driving assistance device 1.

[0043] The ECU 10 sequentially determines whether or not a lane change from lane L1 to lane L2R (L2L) is complete from the point in time when the ECU 10 detects that the right (left) turn signal light has started to operate and temporarily suspends the execution of the ACC processing and the LTA processing. If the ECU 10 detects, based on information acquired from the camera 21, that all wheels of the host vehicle have entered lane L2R (L2L), the ECU 10 determines that the lane change is complete.

[0044] Next, the ECU 10 recognizes the shape of the lane L2R (L2L) (curvature of the curve), and the position (lateral position) and attitude of the host vehicle relative to the lane L2R (L2L) based on information acquired from the camera 21 and the navigation system 23. Next, assuming that the ACC processing and LTA processing are started (restarted) from the current time point (time point t0), the ECU 10 calculates an area (predicted trajectory TR) that the host vehicle is predicted to pass through by time point t1, when the host vehicle is positioned within a predetermined range in the lateral direction of the lane L2R (L2L) (Δd<Δdth) and is oriented approximately parallel to the extension direction of the lane L2R (L2L) (φ<φth) (see FIGS. 3 and 4). Here, the ECU 10 acquires the vehicle speed sp0 at time point t0 (hereinafter referred to as "vehicle speed sp0-a"). When calculating the predicted trajectory TR, the ECU 10 assumes that the host vehicle travels at a vehicle speed sp0-a (travels at a constant speed) during a period T from time t0 to time t1. The ECU 10 also references a map M to obtain an upper limit value θtmax (hereinafter referred to as "upper limit value θtmax-a") corresponding to the vehicle speed sp0-a. The ECU 10 obtains, as the predicted trajectory TR, the shortest trajectory of the host vehicle that satisfies the condition that "during the period T, the host vehicle travels at a constant speed sp0-a and the steering angle θ is equal to or less than the upper limit value θtmax-a."

[0045] As shown in FIG. 3, when the predicted trajectory TR is within (does not deviate from) lane L2R (lane L2L), the ECU 10 determines at time t0 that the condition for starting (cancellation condition) the ACC processing and lane keeping processing is satisfied, and starts (resumes) these processing. In addition, the ECU 10 stops (turns off) the operation of the turn signal lights. The automatic stopping of the operation of the turn signal lights allows the driver to recognize that the ACC processing and LTA processing have been resumed. In other words, the driver can recognize that he or she can entrust driving operations to the driving assistance device 1 to some extent. On the other hand, as shown in FIG. 4, when the predicted trajectory TR deviates from lane L2R (lane L2L), the ECU 10 does not start (resume) the ACC processing and lane keeping processing. In addition, in this case, the ECU 10 does not stop the operation of the turn signal lights. The fact that the operation of the turn signal lights has not been automatically stopped allows the driver to recognize that the ACC processing and LTA processing have not yet been resumed. That is, the driver can recognize that he or she must take the initiative in driving the vehicle.

[0046] As described above, the driving assistance device 1 has a function (pause function) that temporarily disables the ACC function and the LTA function when a lane change from lane L1 to lane L2R (L2L) is initiated, and a function (resume function) that re-enables the ACC function and the LTA function when the lane change is completed and the host vehicle can proceed along lane L2R (L2L). Hereinafter, with reference to FIG. 4, a program PR1 that is executed by the CPU 10a (hereinafter simply referred to as "CPU") of the ECU 10 to realize these functions (pause function and resume function) will be described.

[0047] While the ACC process and the LTA process are being performed (when the ACC switch and the LTA switch are on), the CPU executes the program PR1 shown in Fig. 5 at a predetermined interval. The CPU starts execution of the program PR1 from step 100 and proceeds to step 101.

[0048] In step 101, the CPU determines whether the right (left) turn signal light is operating (flashing). If the CPU determines that the right (left) turn signal light is operating (101: Yes), the CPU proceeds to step 102. On the other hand, if the CPU does not determine that the right (left) turn signal light is operating (101: No), the CPU proceeds to step 107, where it ends execution of program PR1.

[0049] In step 102, the CPU temporarily stops the ACC process and the LTA process. Then, the CPU proceeds to step 103.

[0050] In step 103, the CPU determines whether or not the lane change from lane L1 to lane L2R (L2L) has been completed. If the CPU determines that the lane change has been completed (103: Yes), the CPU proceeds to step 104. On the other hand, if the CPU does not determine that the lane change has been completed (103: No), the CPU returns to step 103. In other words, the CPU repeatedly executes step 103 until the lane change is completed.

[0051] In step 104, the CPU determines whether the predicted trajectory TR is within the lane L2R (L2L) (whether the release condition for releasing the restrictions on the ACC processing and the LTA processing is met). If the CPU determines that the predicted trajectory TR is within the lane L2R (L2L) (104: Yes), the CPU proceeds to step 105. On the other hand, if the CPU does not determine that the predicted trajectory TR is within the lane L2R (L2L) (104: No), the CPU returns to step 104. That is, the CPU repeatedly executes step 104 until the release condition is met. The driver manually drives the vehicle to move it toward the center of the lane L2R (L2L) in the width direction. During this process, the predicted trajectory TR is successively updated. Then, if the release condition is met during this process, the CPU proceeds to step 105.

[0052] In step 105, the CPU stops the operation of the right (left) turn signal light. Then, the CPU proceeds to step 106.

[0053] The CPU resumes the ACC process and the LTA process in step 106, and then the CPU proceeds to step 107, where it ends the execution of the program PR1.

[0054] While the CPU is repeatedly executing step 103, if a situation is assumed in which the driver intentionally aborts the lane change (i.e., manually turns off the turn signal lights), the CPU will forcibly terminate execution of program PR1 and transition the ACC switch and LTA switch to the OFF state. Also, while the CPU is repeatedly executing step 104, a situation is assumed in which the host vehicle deviates from lane L2R (L2L). In this case, the CPU will forcibly terminate execution of program PR1 and transition the ACC switch and LTA switch to the OFF state. When the CPU forcibly terminates execution of program PR1, it is preferable that the CPU cause the alarm device 60 to display a predetermined image and play a predetermined sound.

[0055] (effect) As in the conventional device described above, if the LTA processing is resumed upon completion of a lane change from lane L1 to lane L2R (L2L), the host vehicle may deviate from lane L2R (L2L) within a short period of time after the processing is resumed, resulting in a situation in which the LTA processing (and ACC processing) must be interrupted. When the ECU 10 of the driving assistance device 1 according to this embodiment determines that a lane change from lane L1 to lane L2R (L2L) is completed, the ECU 10 resumes the ACC processing and LTA processing if a condition for determining that the host vehicle can be controlled to proceed along lane L2R (L2L) (a release condition for releasing the restrictions on the ACC processing and the LTA processing) is satisfied (if the predicted trajectory TR is within lane L2R (L2L)). This makes it possible to prevent a situation in which the LTA process must be interrupted within a short period of time (a state in which the vehicle deviates from lane L2R (L2L)) even though the LTA process has been resumed in lane L2R (L2L). That is, according to the driving assistance device 1, the LTA process is resumed at an appropriate timing after the lane change is completed. Also, the turn signal lights are automatically stopped (turned off) when the cancellation condition is met. This allows the driver to recognize that the lane keeping process has been resumed. That is, the driver can recognize that he or she can entrust driving operations (steering) to the driving assistance device to some extent.

[0056] <Modification> As described above, when the ECU 10 detects that the right (left) turn signal lights have started to operate, it temporarily suspends the execution of the ACC process and the LTA process. From that point until the lane change to lane L2R (L2L) is completed, the ECU 10 successively acquires information from the camera 21 and the millimeter-wave radar 22 and, based on the information, successively determines whether it is difficult to execute the LTA process in lane L2R (L2L) (whether the cancellation condition is met). If the ECU 10 determines that the cancellation condition is met, it forcibly turns off the turn signal lights. That is, the driving assistance device 1 may have a function to suggest to the driver that the lane change be suspended. Note that, for example, the ECU 10 determines that the cancellation condition is met when it detects that the width W of lane L2R (L2L) is equal to or smaller than a threshold (the road width is extremely narrow) or when it detects that an obstacle (fallen object) is present in lane L2R (L2L). [Explanation of symbols]

[0057] 1...vehicle control device, 10...ECU, 20...vehicle-mounted sensor, 50...steering device, 70...direction indicator

Claims

1. an on-vehicle sensor including a sensor for acquiring the position and attitude of the host vehicle relative to the lane in which the host vehicle is traveling, and a sensor for acquiring the vehicle speed of the host vehicle; a processor configured to be able to execute a lane keeping process for controlling the host vehicle so that the host vehicle travels along the lane; A driving assistance device comprising: The processor restricts the execution of the lane keeping process when a turn signal light of the host vehicle starts to operate while the host vehicle is traveling in a first lane, and thereafter, when it determines that a lane change to a second lane adjacent to the first lane has been completed and a predetermined release condition for determining that the host vehicle can be controlled to proceed along the second lane is met, the processor stops the operation of the turn signal light and releases the restriction on the execution of the lane keeping process. A driving assistance device configured as follows.

2. The driving assistance device according to claim 1, The driving assistance device is configured such that, when the processor detects that all wheels of the vehicle have entered the second lane based on information obtained from the onboard sensor, it determines that a lane change from the first lane to the second lane has been completed.

3. The driving assistance device according to claim 2, When the processor determines that the lane change is complete, it assumes that the lane keeping process has been resumed from the current point in time, calculates a predicted trajectory (TR), which is the area that the vehicle is predicted to pass through until a predetermined condition regarding the position and attitude of the vehicle relative to the second lane is met by executing the lane keeping process, and determines that the cancellation condition is met if the predicted trajectory falls within the second lane.

4. 4. The driving assistance device according to claim 1, The processor is configured to stop the operation of the turn signal lights if a cancellation condition for determining that it is difficult to perform the lane keeping process in the second lane is met during a period after detecting that the turn signal lights have started to operate while the vehicle is traveling in the first lane and before determining that a lane change from the first lane to the second lane has been completed.

5. The driving assistance device according to claim 4, The driving assistance device is configured such that the processor determines that the cancellation condition is met when the width of the second lane is equal to or less than a threshold value or when an obstacle is present in the second lane.

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