Driving Support Devices

Abstract

To execute steering assist control so that the whole of vehicles can perform a smooth lane change even when a vehicle travels with a towed vehicle connected thereto.SOLUTION: An operation assist device comprises: a surrounding information acquisition section 11 which acquires information related to a three-dimensional object existing around a vehicle and a compartment line extended ahead of the vehicle as surrounding information; a vehicle speed detection unit 12; and a control unit 10 which executes lane keeping assist control and lane change assist control as steering assist control. The control unit: determines whether or not a towing condition that a vehicle is connected to a towed vehicle is met on the basis of the surrounding information and a vehicle speed; and makes lane change time longer when a condition to start the lane change assist control and the towing condition are met than when the towing condition is not met.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a driving assistance device capable of executing steering assistance control so that a vehicle to which a towed vehicle is coupled can smoothly change lanes. [Background technology]

[0002] Conventionally, a driving assistance device is known that is mounted on a vehicle and is capable of executing steering assistance control for assisting the steering operation of a driver of the vehicle. The steering assistance control includes lane tracing assist control (LTA) and lane changing assist control (LCA). The lane tracing assist control is a control that assists the steering operation so that the vehicle's traveling position is maintained at a predetermined position (typically, the center position) in the lane width direction of the lane. The lane changing assist control is a control that assists the steering operation so that the vehicle moves from the original lane in which the vehicle is currently traveling to a target lane adjacent to the original lane. Hereinafter, a vehicle equipped with a driving assistance device is also referred to as a "host vehicle". The lane tracing assist control and lane changing assist control are also referred to as "LTA" and "LCA", respectively.

[0003] The driving assistance device starts LCA when a predetermined start condition is satisfied, and ends LCA when the host vehicle has completed moving to the target lane. The start condition of LCA includes that LTA is being executed. Therefore, when the start condition of LCA is satisfied, LTA is switched to LCA, and when the host vehicle has completed moving to the target lane, LCA is terminated and LTA is resumed. That is, lane changing is performed by LCA and LTA.

[0004] A towed vehicle can be coupled to a vehicle using a predetermined coupling (typically, a hitch ball and a hitch coupler). The towed vehicle is, for example, a camper trailer or a boat trailer. When a towed vehicle is coupled to a vehicle, the weight of the entire vehicle (i.e., the vehicle itself and the towed vehicle) increases and the overall length of the vehicle also increases. For this reason, when the vehicle travels with the towed vehicle coupled, there is a significant change in turning characteristics compared to when the vehicle travels alone. Here, since the LCA and LTA are designed to realize smooth lane changes based on the weight and overall length of the vehicle itself, when a normal lane change is performed with a towed vehicle coupled, there is a problem that the entire vehicle may sway or the LCA may be canceled due to the LCA not being performed properly.

[0005] Patent document 1 describes a technology in which a driving assistance device capable of performing autonomous driving performs lane changes by autonomous driving of the vehicle itself when a towed vehicle is coupled (hereinafter simply referred to as the "towing state"). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2019-123299 A Summary of the Invention

[0007] Patent Document 1 only describes how the burden on the driver is reduced by not switching from automatic to manual driving when the vehicle is changing lanes while towing, and it is difficult to say that sufficient consideration has been given to how changes in turning characteristics should be taken into account when changing lanes using automatic driving while towing.

[0008] The present invention has been made to address the above-mentioned problems. That is, one of the objects of the present invention is to provide a driving assistance device that can execute steering assistance control so that the entire vehicle changes lanes smoothly even when the vehicle is traveling with a towed vehicle coupled thereto.

[0009] The driving assistance device according to the present invention (hereinafter referred to as the "device of the present invention") comprises: It is installed in a vehicle (V), a surrounding information acquisition device (11) that detects three-dimensional objects present around the vehicle and a marking line extending in front of the vehicle, and acquires information about the detected three-dimensional objects and marking lines as surrounding information; a vehicle speed detection device (12) capable of detecting a speed (v) of the vehicle; As a steering assist control for assisting a steering operation of a driver of the vehicle, a lane keeping assist control (LTA) is executed to assist the steering operation so that the traveling position of the vehicle is maintained at a predetermined position in a lane width direction of the lane based on the surrounding information, and a lane change assist control (LCA) is executed to assist the steering operation so that the vehicle moves from an original lane (L1) in which the vehicle is currently traveling to a target lane (L2) adjacent to the original lane based on the surrounding information, The lane change assist control is started when a predetermined start condition is satisfied, including the lane keeping assist control being executed (condition 1b), and is ended when the movement to the target lane is completed; When the lane change assist control is ended, the lane keeping assist control is resumed. A control unit (10) configured as described above; Equipped with. A time required for the vehicle to move from a predetermined position in the lane width direction of the original lane to a predetermined position in the lane width direction of the target lane by the lane change assist control and the lane keeping assist control is defined as a lane change time (T). The control unit When the speed (v) of the vehicle (V) is equal to or greater than a predetermined speed threshold (vth), the speed (vr) of a rear three-dimensional object that is a three-dimensional object detected behind the vehicle by the surrounding information acquisition device (11) is approximately the same as the speed of the vehicle, and at least a part of the rear three-dimensional object is present within a predetermined first rear area (R1) defined behind the vehicle, A towing condition is satisfied when a towed vehicle is connected to the vehicle. and Judge (step 540: Yes ), When the start condition of the lane change assist control is satisfied, if the towing condition is satisfied (step 440: Yes), the lane change time is increased compared to when the towing condition is not satisfied (step 440: No). Among these, a specific time (Ts) is a time required for the vehicle (V) to move from the original lane (L1) to the target lane (L2) in the lane width direction. Longer and extending the section of the travel path, which is the path on which the lane change is performed, corresponding to the specific time in the direction in which the original lane and the target lane extend. (step 460), It is structured as follows: And, The first rear region (R1) is defined as having an origin at the center of the front bumper of the vehicle, an x-axis with a positive direction toward the right, and a y-axis with a positive direction toward the front, and w is the vehicle width of the vehicle, m is a predetermined margin, L is the length of the vehicle in the front-rear direction, and d1 is a predetermined length, and is expressed by the following equation: -w / 2-m≦x≦w / 2+m -L-d1≦y≦-L is defined by The margin m and the length d1 are set to values ​​that prevent a following vehicle traveling at approximately the same speed as the vehicle or another vehicle traveling in an adjacent lane from entering the first rear area.

[0010] In the device of the present invention, when the start condition of the lane change assist control is satisfied and the towing condition is satisfied, the lane change time ( In particular, the specific times described below) is lengthened. This reduces the speed of the vehicle in the lane width direction when changing lanes. In addition, the vehicle's running trajectory becomes longer in the direction of the extension of the lane (the direction perpendicular to the lane width direction) by the amount of time required for lane change, so the shape of the running trajectory becomes gentler, and the rate of change of the yaw angle of the vehicle when changing lanes (i.e., the yaw rate) is reduced. With this configuration, a vehicle in a towing state can change lanes more slowly and slowly than a vehicle running alone. Therefore, even if the weight of the entire vehicle increases and the overall length increases due to the towed vehicle being coupled to the vehicle, the entire vehicle is less likely to wobble. In addition, since the lane change assist control is appropriately executed, the control is less likely to be canceled. As a result, according to the device of the present invention, steering assist control can be executed so that the entire vehicle changes lanes smoothly even when the vehicle is running with the towed vehicle coupled to it. Furthermore, when a towed vehicle is coupled to a vehicle, a significant change occurs in the turning characteristics. Therefore, the sway of the vehicle caused by the coupling of the towed vehicle is more likely to occur when the vehicle is moving in the lane width direction from the original lane to the target lane than when the vehicle is traveling along the lane. Therefore, by lengthening the specific time, which is the "time required for the vehicle to move in the lane width direction from the original lane to the target lane," and lengthening the section of the travel trajectory corresponding to the specific time in the extension direction of the original lane and the target lane, it is possible to effectively suppress the sway of the towed vehicle when changing lanes. Furthermore, according to the towing conditions, by setting the vehicle speed threshold to an appropriate value and by appropriately setting the position and size of the first rear area, it is possible to accurately determine whether the rear three-dimensional object is a towed vehicle, a following vehicle, or another vehicle traveling in an adjacent lane, thereby ensuring the reliability of the towing conditions.

[0013] In one aspect of the invention, The control unit (10) When the vehicle (V) has finished crossing the boundary line (WL) between the original lane (L1) and the target lane (L2) due to the lane change assist control (LCA), it is determined that the vehicle (V) has completed moving to the target lane (WL), and the lane change assist control is terminated. It is structured as follows.

[0018] In the above description, in order to facilitate understanding of the invention, the symbols used in the embodiments are added in parentheses to the constituent elements of the invention corresponding to the embodiments, but each constituent element of the invention is not limited to the embodiment defined by the said symbols. [Brief description of the drawings]

[0019] [Figure 1] 1 is a schematic configuration diagram of a driving assistance device (embodiment device) according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a diagram showing how a vehicle traveling alone changes lanes using LCA and LTA. [Diagram 3] FIG. 1 is a diagram showing how a vehicle to which a towed vehicle is coupled changes lanes using LCA and LTA. [Figure 4] 4 is a flowchart showing a routine executed by a CPU of a driving assistance ECU of the embodiment of the present invention. [Diagram 5] 4 is a flowchart showing a routine executed by a CPU. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] (composition) Hereinafter, a driving assistance device according to an embodiment of the present invention (hereinafter, also referred to as "the embodiment device") will be described with reference to the drawings. As shown in FIG. 1, the embodiment device includes a driving assistance ECU 10, and a surrounding sensor 11, a vehicle speed sensor 12, a driving operation state sensor 13, a setting operation device 14, a turn signal switch (turn signal SW) 15, a driving device 21, a braking device 22, a steering device 23, and a turn signal 24, all connected thereto. The driving assistance ECU 10 includes a microcomputer as a main part. ECU is an abbreviation of Electronic Control Unit. The microcomputer includes a CPU, a ROM, a RAM, an interface (I / F), and the like, and the CPU is adapted to realize various functions by executing instructions (programs, routines) stored in the ROM. Note that some of these functions may be executed by another ECU (not shown). Hereinafter, a vehicle equipped with the embodiment device will be referred to as a "host vehicle".

[0021] The driving assistance ECU 10 is configured to acquire signals output, detected or generated by the sensors and switches 11 to 15 at predetermined time intervals, and control the elements 21 to 24 based on the acquired signals. Hereinafter, the driving assistance ECU 10 is also simply referred to as "ECU 10."

[0022] The surrounding sensor 11 (surrounding information acquisition device) includes a camera sensor 11a and a radar sensor 11b. The camera sensor 11a is installed on the rear surface of the inner mirror (room mirror / rear-view mirror) of the vehicle. The camera sensor 11a photographs the scenery ahead (including the front and sides) of the vehicle and recognizes the lane lines based on the photographed image data. The lane lines are lines marked on the road to divide the traffic of vehicles according to the direction. The lane lines include solid lane lines and broken lane lines. The solid lane lines are continuously marked on the road and include white lane lines and yellow lane lines. The broken lane lines are intermittently marked on the road at a predetermined interval and include white lane lines. In this specification, the area between two adjacent lane lines is defined as a lane. The camera sensor 11a calculates the shape of the lane based on the recognized lane lines.

[0023] In addition, the camera sensor 11a calculates the presence or absence of a three-dimensional object and the relative relationship between the vehicle and the three-dimensional object based on the image data. The three-dimensional object includes moving objects (other vehicles, etc.) and fixed objects (guardrails, side walls, median strips, roadside trees, etc.). Note that the term "moving object" refers to an object that can move, but does not mean that it is constantly moving. Also, the "relative relationship between the vehicle and the three-dimensional object" refers to the distance from the vehicle to the three-dimensional object, the orientation of the three-dimensional object relative to the vehicle, and the relative speed of the three-dimensional object relative to the vehicle.

[0024] That is, the camera sensor 11a has a function of detecting "a three-dimensional object present in front of the vehicle and a dividing line extending in front of the vehicle" and acquiring information on the detected three-dimensional object and dividing line. The "dividing line extending in front of the vehicle" also includes the left and right dividing lines that respectively define the left adjacent lane and the right adjacent lane (lanes adjacent to the left and right side of the lane in which the vehicle is currently traveling).

[0025] The radar sensor 11b is installed at the left and right corners of the rear bumper of the vehicle. The radar sensor 11b irradiates millimeter wave band radio waves to the rear (including the rear sides) of the vehicle, and receives reflected waves from a three-dimensional object if one is present. The radar sensor 11b calculates the presence or absence of a three-dimensional object and the relative relationship between the vehicle and the three-dimensional object based on the irradiation timing and reception timing of the radio waves, etc.

[0026] That is, the radar sensor 11b has a function of detecting "a three-dimensional object existing behind the vehicle" and acquiring information about the detected three-dimensional object. Note that, instead of or in addition to the radar sensor 11b, other sensors (for example, a camera sensor for a PVM (Panoramic View Monitor), a clearance sonar, or a laser radar) may be adopted.

[0027] The information acquired by the surroundings sensor 11 (information about three-dimensional objects existing around the host vehicle and about marking lines extending ahead of the host vehicle) is referred to as surroundings information. The surroundings sensor 11 outputs the surroundings information to the ECU 10.

[0028] The vehicle speed sensor 12 (vehicle speed detection device) detects the speed of the host vehicle (vehicle speed). The driving operation state sensor 13 includes a plurality of sensors for detecting the driving operation state. Specifically, the driving operation state sensor 13 includes a steering angle sensor for detecting the steering angle of the steering wheel, a steering torque sensor for detecting the steering torque, and the like.

[0029] The setting operator 14 is an operator operated by the driver to set (select) whether or not the driver desires to execute each of adaptive cruise control (ACC, hereinafter also referred to as "ACC"), lane keeping assist control (LTA), and lane change assist control (LCA). The setting operator 14 generates an ACC-on signal when execution of ACC is selected, generates an LTA-on signal when execution of LTA is selected, and generates an LCA-on signal when execution of LCA is selected. The setting operation device 14 also functions as an operation device for determining a set distance and a set vehicle speed of the ACC (both of which will be described later).

[0030] However, the setting operator 14 is configured so that the execution of LTA and LCA cannot be selected if the execution of ACC is not selected, and so that the execution of LCA cannot be selected if the execution of LTA is not selected.

[0031] The turn signal switch 15 is provided on a turn signal lever (not shown). The turn signal lever is an operating device operated by the driver to activate (blink) the turn signal 24, and is provided on a steering column (a component of a steering mechanism described later). In this embodiment, the turn signal lever is operated when the driver makes a left or right turn or changes lanes by driving the vehicle himself, and is also operated when the driver wishes to execute LCA (i.e., execute a lane change).

[0032] Specifically, the turn signal lever is configured to be movable to a first left position or a first right position, which are positions rotated counterclockwise or clockwise by a predetermined angle θ1 from a neutral position about a pivot. Also, the turn signal lever is configured to be movable to a second left position or a second right position, which are positions rotated counterclockwise or clockwise by a predetermined angle θ2 larger than the angle θ1 from the neutral position about a pivot. Hereinafter, when it is not necessary to distinguish between the first left position and the first right position, these will be collectively referred to as the "first position," and when it is not necessary to distinguish between the second left position and the second right position, these will be collectively referred to as the "second position."

[0033] When the winker lever is moved to the first position by the driver's lever operation, it returns to the neutral position when the driver's lever operating force is released. On the other hand, when the turn signal lever is moved to the second position by the driver's lever operation, the lock mechanism holds the turn signal lever in the second position even if the lever operation force is released. When the steering wheel is rotated in the reverse direction and returned to the neutral position while the turn signal lever is held in the second position, or when the driver performs an operation to move the turn signal lever toward the neutral position, the lock mechanism is released and the turn signal lever returns to the neutral position.

[0034] The turn signal SW 15 has a first SW 15a and a second SW 15b. The first SW 15a includes a first left SW 15aL that is turned on (generates an ON signal) only when the turn signal lever is in the first left position, and a first right SW 15aR that is turned on (generates an ON signal) only when the turn signal lever is in the first right position. The second SW 15b includes a second left SW 15bL that is turned on (generates an ON signal) only when the turn signal lever is in the second left position, and a second right SW 15bR that is turned on (generates an ON signal) only when the turn signal lever is in the second right position.

[0035] The ECU 10 detects the operation state of the turn signal lever based on the presence or absence of an ON signal from the first SW 15a and the second SW 15b, and blinks the turn signal 24 corresponding to the operation direction of the turn signal lever based on the operation state of the turn signal lever (described later).

[0036] When the driver turns left or right or changes lanes through his / her own driving operation, the driver moves the turn signal lever to the second left position or the second right position. On the other hand, when the driver wishes to execute LCA (to change lanes), the driver moves the turn signal lever to the first position (strictly speaking, the first position corresponding to the desired direction of LCA, between the first left position and the first right position) and holds that state. The ECU 10 is configured to measure the time that the turn signal lever is continuously held in the first position. When the hold time of the turn signal lever is equal to or longer than a predetermined time (hereinafter also referred to as the "LCA request determination time"), the ECU 10 determines that an LCA request signal has been issued from the first SW 15a. The LCA request determination time is, for example, one second. That is, when the driver wishes to execute LCA, the driver only needs to hold the turn signal lever in the first position for the LCA request determination time or longer.

[0037] It should be noted that the operation device operated by the driver when the driver desires to execute LCA is not limited to the turn signal lever, and for example, a dedicated operation device may be provided.

[0038] The drive device 21 is a device for applying a driving force to the drive wheels of the host vehicle to make the host vehicle run. For example, if the host vehicle is a hybrid vehicle, the drive source of the drive device 21 is an engine and a motor. The ECU 10 controls the operation of the drive device 21 to control the driving force applied to the drive wheels. Note that the type of the host vehicle is not limited to a hybrid vehicle, and may be, for example, an engine vehicle, a plug-in hybrid vehicle, a fuel cell vehicle, an electric vehicle, or the like.

[0039] The braking device 22 is a device for applying a braking force to the wheels of the host vehicle in order to brake the host vehicle. The ECU 10 controls the operation of the braking device 22 to control the braking force applied to the wheels.

[0040] The steering device 23 is a device for applying a steering torque to the steering mechanism for steering the steered wheels of the vehicle. Specifically, the steering device 23 includes a motor driver (not shown) and a steering motor connected to the motor driver. The steering motor is incorporated in the steering mechanism. The steering motor generates a steering torque by electric power supplied from the motor driver, and applies this steering torque to the steering mechanism. The ECU 10 controls the operation of the steering device 23 to control the steering torque applied to the steering mechanism (and thus the steering angle of the steered wheels).

[0041] The turn signals 24 include a left turn signal 24L and a right turn signal 24R. The left turn signal 24L is installed at the left front corner and the left rear corner of the vehicle. The right turn signal 24R is installed at the right front corner and the right rear corner of the vehicle. The ECU 10 blinks the corresponding turn signal 24 while the turn signal lever is in the first position or the second position (i.e., while the first SW 15a or the second SW 15b is generating an ON signal). In addition, when an LCA start condition, which will be described later, is satisfied and an LCA is started, the ECU 10 starts blinking of the corresponding turn signal 24, and keeps the turn signal 24 blinking while the LCA is being executed. That is, the ECU 10 blinks the corresponding blinker 24 while at least one of condition A that the blinker lever is in the first position or the second position and condition B that LCA is being executed is satisfied, and ends the blinking of the blinker 24 (turns off) when neither of these conditions is satisfied. According to this configuration, once the ECU 10 starts the LCA, the ECU 10 continues to blink the blinker 24 while the LCA is being executed (in other words, until the LCA is terminated) even if the blinker lever returns to the neutral position from the first position. Instead of the above condition, condition B may be a condition that "a predetermined time (e.g., 0.5 seconds) has elapsed since the vehicle has finished crossing the dividing line at the boundary between the original lane and the target lane due to LCA." According to this configuration, when the turn signal lever is in the neutral position after the start of LCA, ECU 10 turns off the turn signal 24 when a predetermined time has elapsed since the end of LCA. In other words, the timing of turning off the turn signal 24 does not have to be the same as the timing of ending the LCA.

[0042] (Details of operation) Next, the operation of the ECU 10 will be described in detail. The ECU 10 is configured to be able to execute ACC, LTA, and LCA. All of these controls are well known. As will be described in detail later, the ECU 10 is configured to be able to execute lane changing by LCA and LTA. Since the present embodiment device is characterized in that it changes the lane changing behavior based on whether or not a towed vehicle is connected to the vehicle, the following will describe in detail the controls related to the characteristic parts, and only provide an overview of the other controls. Note that LTA and LCA are types of steering assist control.

[0043] [ACC] The ECU 10 executes the ACC when it receives an ACC ON signal from the setting operation device 14. Specifically, the ECU 10 judges whether or not there is a preceding vehicle based on surrounding information. If it is judged that there is a preceding vehicle, the ECU 10 controls the vehicle speed so that the inter-vehicle distance from the preceding vehicle is maintained at a predetermined set distance. On the other hand, if it is judged that there is no preceding vehicle, the ECU 10 controls the vehicle speed so that the host vehicle travels at a predetermined set vehicle speed. The set distance and set vehicle speed can be changed within a predetermined range by the driver operating the setting operation device 14.

[0044] [LTA] The ECU 10 starts the LTA when an LTA start condition is satisfied. The LTA start condition is satisfied, for example, when all of the following conditions are satisfied. (Condition 1a) ACC is being executed. (Condition 2a) An LTA ON signal is obtained from the setting controller 14. (Condition 3a) The surrounding information includes lane markings that define the driving lanes. However, any other conditions may be added in place of or in addition to the above conditions.

[0045] When the LTA start condition is satisfied, the ECU 10 controls the steering device 23 so that the vehicle's driving position is maintained at the center position in the lane width direction (hereinafter also referred to as the "lateral direction") of the driving lane (in other words, the vehicle drives along the center line of the driving lane). Here, "the vehicle's driving position is maintained at the center position in the lateral direction of the driving lane" means that "the vehicle is located at the center of the lateral direction of the driving lane and the yaw angle (the angle between the front and rear axes of the vehicle and the center line of the driving lane) is maintained at approximately zero". That is, during the execution of the LTA, the ECU 10 calculates the center position in the lateral direction of the driving lane based on the surrounding information and sets the target yaw angle to zero, calculates a target steering angle such that the vehicle is located at the center position and the yaw angle coincides with the target yaw angle, and controls the steering device 23 so that a steering torque is applied to the steering mechanism such that the steering angle of the steered wheels coincides with the target steering angle. The "center line" is a virtual line that passes through the lateral center position of the lane and extends in the direction in which the lane extends, and can be calculated by the ECU 10 based on surrounding information. Hereinafter, the "lateral center position of the lane" is also simply referred to as the "center position of the lane." In this embodiment, the LTA maintains the host vehicle in the center position of the traveling lane, but the position where the host vehicle is maintained in the traveling lane is not limited to the center position.

[0046] [LCA] The ECU 10 starts the LCA when an LCA start condition is satisfied. The LCA start condition is satisfied, for example, when all of the following conditions are satisfied. (Condition 1b) LTA is being executed. (Condition 2b) An LCA ON signal is obtained from the setting controller 14. (Condition 3b) An LCA request signal is obtained from the first SW 15a. (Condition 4b) The lane marking in the direction in which the turn signal lever is operated, which is included in the surrounding information (i.e., the boundary lane marking that is the boundary between the original lane and the target lane), is a white dashed lane marking. (Condition 5b) The surrounding information does not include any solid objects (typically, other vehicles) that may prevent movement to the target lane. (Condition 6b) The vehicle speed is within a predetermined LCA vehicle speed range (for example, 60 km / h or more and 130 km / h or less). (Condition 7b) The road on which the vehicle is traveling is a highway for motor vehicles only.

[0047] Whether or not condition 7b is satisfied may be determined based on road type information obtained from a navigation system (not shown), for example. However, any condition may be added in place of or in addition to the above conditions. For example, a condition that "hands-off warning is not issued while LTA is being performed" may be added. The hands-off warning is a warning issued when the driver is not holding the steering wheel, and may be issued by sounding a buzzer, for example.

[0048] When the LCA start condition is satisfied, the ECU 10 controls the steering device 23 so that the host vehicle moves from the original lane to the target lane (the lane adjacent to the original lane in the direction of the operation of the turn signal lever). When the host vehicle finishes crossing the boundary dividing line (described later), the ECU 10 determines that the host vehicle has completed moving to the target lane, terminates the LCA, and resumes the LTA from that point. In other words, when the LCA ends (when the LTA is resumed), the host vehicle is not yet located in the center position of the target lane, and the yaw angle of the host vehicle deviates from the target yaw angle. When the LTA is resumed, the host vehicle moves to the center position of the target lane, and the vehicle's driving position is maintained in the center position.

[0049] In this specification, the movement of the host vehicle during the period from "the point when the LCA start condition is satisfied in the original lane" to "the point when the LCA ends in the target lane, the LTA is resumed, and the host vehicle's driving position moves to the center position of the target lane (driving lane)" is defined as "lane change from the original lane to the target lane." In other words, lane change is an operation realized by a combination of "the operation of the host vehicle moving from the original lane to the target lane by LCA" and "the operation of the host vehicle moving to the center position of the target lane by LTA." In addition, the time required for the host vehicle to change lanes by LCA and LTA is defined as "lane change time T."

[0050] A more detailed description will be given with reference to FIG. 2. FIG. 2 is a diagram showing a state in which the vehicle V changes lanes from lane L1 (original lane) to lane L2 (target lane) by LCA and LTA. Time points tn1 to tn6 each represent a specific time point. Time point tnk+1 (k: an integer from 1 to 5) is a time point after time point tnk. In this example, it is assumed that at time point tn1, LTA is being executed (i.e., the vehicle V is traveling along the center line CL1 of lane L1), the setting operation device 14 generates an LCA-on signal, and the vehicle V is traveling at a constant speed on a motorway at a vehicle speed within the LCA vehicle speed range. In addition, as shown in FIG. 2, the boundary dividing line WL is a white dashed dividing line. Furthermore, there is no solid object that may prevent the vehicle V from moving to lane L2. Therefore, at time point tn1, conditions 1b, 2b, 4b to 7b are satisfied.

[0051] The driver moves the turn signal lever to the first right position at time tn1 and holds the state. As a result, the ECU 10 determines that condition A is satisfied and starts blinking the right turn signal 24R at time tn1. When the holding time reaches the LCA request determination time at time tn2, condition 3b is satisfied. If conditions 1b, 2b, 4b to 7b that were satisfied at time tn1 continue to be satisfied at time tn2, conditions 1b to 7b are all satisfied at time tn2, and the LCA start condition is satisfied, so that the ECU 10 starts the LCA at that time tn2. In this example, it is assumed that the turn signal lever is returned to the neutral position after the start of the LCA. In this case, the ECU 10 determines that condition B is satisfied after the start of the LCA and continues blinking the right turn signal 24R.

[0052] When the ECU 10 starts the LCA, it sets (selects) the lane change time T from a predetermined time range based on various conditions (e.g., surrounding information and vehicle state, etc.). When the host vehicle V is traveling alone (traveling without a towed vehicle coupled) as in the example of FIG. 2, the ECU 10 sets the time T1 as the lane change time T. Then, it calculates the travel trajectory Rn based on the vehicle speed, the lane change time T (= T1), and the lane distance (the distance between the center line CL1 of the lane L1 and the center line CL2 of the lane L2), etc. The travel trajectory Rn is a trajectory that moves the host vehicle V from the center position of the lane L1 to the center position of the lane L2 over the lane change time T (= T1). The lane change is performed by the host vehicle V moving along the travel trajectory Rn from the start point to the end point of the travel trajectory Rn. As is apparent from the above description, when the ECU 10 starts the LCA, it sets the lane change time T and calculates the traveling trajectory Rn, thereby starting the lane change.

[0053] The ECU 10 calculates a lateral speed (vehicle speed in the lateral direction) and a yaw angle for moving the host vehicle V along the travel path Rn as a target lateral speed and a target yaw angle, respectively, every time a predetermined time elapses, and controls the steering device 23 so that the lateral speed and the yaw angle of the host vehicle V coincide with the target lateral speed and the target yaw angle.

[0054] Points Pn2 to Pn6 are points on the travel path Rn. Points Pn2 and Pn6 are located at the start and end points of the travel path Rn, respectively. The travel path Rn approximately coincides with the center line CL1 in the section from point Pn2 to point Pn3, and smoothly displaces from the center line CL1 to the center line CL2 in the section from point Pn3 to point Pn6. Furthermore, point Pn4 is a point where the right front wheel of the host vehicle V approaches the boundary demarcation line WL, and point Pn5 is a point immediately after the left rear wheel of the host vehicle V passes the boundary demarcation line WL. The positions of points Pn4 and Pn5 can be calculated based on the shape of the travel path Rn and the shape of the host vehicle V.

[0055] The time points tn2 to tn6 correspond to the points Pn2 to Pn6, respectively. Therefore, when the ECU 10 starts the LCA at the time point tn2, the host vehicle V travels in the lane L1 along the travel path Rn from the time point tn2 to the time point tn3, starts moving laterally at the time point tn3, starts crossing the boundary line WL at the time point tn4, and finishes crossing the boundary line WL at the time point tn5. As a result, the ECU 10 determines that the host vehicle V has completed moving to the lane L2 at the time point tn5, ends the LCA, turns off the right blinker 24R, and resumes the LTA. Thereafter, the host vehicle V moves along the travel path Rn and finishes moving laterally at the time point tn6. That is, the travel position of the host vehicle V moves to the center position of the lane L2 at the time point tn6. The movement of the host vehicle V during the period from time tn2 to time tn6 corresponds to a lane change (T1=tn6-tn2). Note that the host vehicle V moves laterally from lane L1 to lane L2 during the period from time tn3 to time tn6. Hereinafter, the time required for the host vehicle V to move laterally from lane L1 to lane L2 is defined as a "specific time Ts." The specific time Ts is included in the lane change time T. In the example of FIG. 2, the ECU 10 sets the time Ts1 as the specific time Ts (Ts1=tn6-tn3).

[0056] A towed vehicle can be coupled to the vehicle using a specified coupler. When a towed vehicle is coupled, the weight of the entire vehicle increases and the overall length of the vehicle increases, resulting in a significant change in turning characteristics compared to when the vehicle is traveling alone. Therefore, when a normal lane change is performed with a towed vehicle coupled, there is a problem that the entire vehicle may sway or the LCA may be canceled.

[0057] Therefore, the ECU 10 performs a towing condition determination to determine whether or not the towing condition that is met when a towed vehicle is connected to the vehicle itself is met, and is configured to lengthen the lane change time T (strictly speaking, the specific time Ts) when the towing condition is met compared to when the towing condition is not met.

[0058] First, the towing conditions will be described. The ECU 10 determines that the towing conditions are met when all of the following conditions are met. (Condition 1c) The vehicle speed v is equal to or greater than a predetermined vehicle speed threshold vth. (Condition 2c) The speed vr of a three-dimensional object (described later) behind the vehicle, which is included in the surrounding information, is substantially the same as the vehicle speed v. (Condition 3c) At least a portion of the rear three-dimensional object that satisfies condition 2c is present within the predetermined rear region R1.

[0059] The vehicle speed threshold vth in condition 1c is set to the minimum vehicle speed v at which the host vehicle is estimated not to be caught in traffic. The vehicle speed threshold vth can be determined in advance by experiment or simulation.

[0060] The three-dimensional object behind in condition 2c is a three-dimensional object detected by the radar sensor 11b. The ECU 10 determines that condition 2c is satisfied when the magnitude of the difference |vr-v| between the speed vr of the three-dimensional object behind and the vehicle speed v is equal to or smaller than a predetermined difference threshold Δv (Δv: a predetermined value that can be selected within a range of 1 to 2 [km / h]).

[0061] Here, if the origin is set at the center of the front bumper of the vehicle, the x-axis has a positive direction to the right, and the y-axis has a positive direction forward, the rear region R1 of condition 3c is defined by the following equation. -w / 2-m≦x≦w / 2+m -L-d1≦y≦-L w represents the vehicle width of the host vehicle, m represents a predetermined margin, and L represents the overall length (length in the front-rear direction) of the host vehicle. That is, the rear region R1 is a rectangular region with a length in the x-axis direction of w+2m and a length in the y-axis direction of d1, and is symmetrical with respect to the y-axis. The rear region R1 is defined so as to contact the rear end of the host vehicle. The margin m and the length d1 are set to values ​​such that, when the host vehicle satisfies the condition 1c and the following vehicle or another vehicle traveling in an adjacent lane satisfies the condition 2c, the following vehicle or the other vehicle cannot enter the rear region R1. These values ​​can be set by experiments or simulations, and in this embodiment, the margin m can be set to 0.7 [m] and the length d1 can be set to 5 [m]. However, the values ​​of the margin m and the length d1 are not limited to these. The ECU 10 determines that the condition 3c is satisfied when at least a portion of the rear three-dimensional object that satisfies the condition 2c is present within the rear area R1. The rear area R1 corresponds to an example of the "first rear area."

[0062] When the vehicle is traveling without being caught in traffic, if a three-dimensional object behind is traveling at a vehicle speed vr that is substantially the same as the vehicle speed v, and at least a part of the three-dimensional object behind is present within the rear region R1, the three-dimensional object behind is highly unlikely to be a following vehicle or another vehicle traveling in an adjacent lane, and is highly likely to be a towed vehicle coupled to the vehicle. Therefore, by configuring the towing condition to be satisfied when the above conditions 1c to 3c are satisfied, it is possible to accurately determine whether a towed vehicle is coupled to the vehicle behind.

[0063] Next, the lane change time when a towed vehicle is coupled to the host vehicle will be described with reference to Fig. 3. Fig. 3 is a diagram showing how the host vehicle V changes lanes from lane L1 (original lane) to lane L2 (target lane) by the LCA and LTA with the towed vehicle Vt coupled to it. In this example, the towing condition is met. Time points tt1 to tt6 all represent specific time points. Time point ttk+1 (k: an integer from 1 to 5) is a time point later than time point ttk. In the following description, the host vehicle V in a towed state may be simply referred to as "host vehicle V".

[0064] The behavior of the host vehicle V from time tt1 to time tt6 corresponds to the behavior of the host vehicle V from time tn1 to time tn6 in Fig. 2. Therefore, at time tt1, the driver moves the turn signal lever to the first right position and maintains that state. Then, at time tt2, the maintenance time reaches the LCA request determination time and condition 3b is satisfied (i.e., the LCA start condition is satisfied at time tt2). As a result, the ECU 10 starts blinking the right turn signal 24R at time tn1, and starts LCA at time tt2 while continuing to blink the right turn signal 24R.

[0065] When the ECU 10 starts the LCA, it sets the lane change time T in the same manner as in the example of FIG. 2. However, since the towing condition is satisfied in this example, the ECU 10 sets the lane change time T to a time T2 that is a value greater than the time T1. That is, the ECU 10 is configured to lengthen the lane change time T when the towing condition is satisfied compared to when the towing condition is not satisfied. More specifically, the ECU 10 sets the time Ts2 that is a time greater than the time Ts1 as the specific time Ts, thereby lengthening the lane change time T. The time Ts2 may be determined by multiplying the time Ts1 by a predetermined factor. In this case, the predetermined factor may be a variable that increases with an increase in the vehicle speed. Alternatively, the time Ts2 may be determined by adding a predetermined time to the time Ts1. In this case, the predetermined time may be a variable that increases with an increase in the vehicle speed.

[0066] When the ECU 10 sets the lane change time T (= T2), it calculates a travel trajectory Rt based on the vehicle speed, the lane change time T, the lane distance, etc. The travel trajectory Rt is a trajectory that moves the host vehicle V from the center position of the lane L1 to the center position of the lane L2 over the lane change time T (= T2). The host vehicle V moves along the travel trajectory Rt from the start point to the end point of the travel trajectory Rt, thereby performing a lane change.

[0067] The ECU 10 calculates the lateral speed and the yaw angle for moving the host vehicle V along the travel path Rt as the target lateral speed and the target yaw angle, respectively, every time a predetermined time elapses, and controls the steering device 23 so that the lateral speed and the yaw angle of the host vehicle V coincide with the target lateral speed and the target yaw angle.

[0068] When the ECU 10 starts the LCA at time tt2, the host vehicle V travels in the lane L1 along the travel path Rt from time tt2 to time tt3, starts moving laterally at time tt3, starts crossing the boundary line WL at time tt4, and finishes crossing the boundary line WL at time tt5. As a result, the ECU 10 ends the LCA at time tt5, turns off the right turn signal 24R, and resumes the LTA. After that, the host vehicle V travels along the travel path Rt and finishes moving laterally at time tt6. That is, the travel position of the host vehicle V moves to the center position of the lane L2 at time tt6. The movement of the host vehicle V from time tt2 to time tt6 corresponds to a lane change (T2=tt6-tt2). Also, the period from time tt3 to time tt6 corresponds to the specific time Ts (=Ts2) (Ts2=tt6-tt3).

[0069] By lengthening the specific time Ts, the section of the travel trajectory Rt corresponding to the specific time Ts is longer in the extension direction of the lanes L1 and L2 compared to the same section of the travel trajectory Rn (see FIG. 2). In other words, the shape of the travel trajectory Rt in that section becomes gentler (the curvature is smaller).

[0070] The lane distance is the same in FIG. 2 and FIG. 3. Therefore, by lengthening the specific time Ts, the lateral speed of the host vehicle V when traveling in the section of the traveling trajectory Rt corresponding to the specific time Ts can be reduced. In addition, by lengthening the traveling trajectory Rt in the direction of the extension of the lane, the rate of change of the yaw angle (i.e., the yaw rate) when the host vehicle V moves laterally from the lane L1 to the lane L2 can be reduced. According to this configuration, the host vehicle V in the towing state can change lanes more slowly and slowly compared to the host vehicle V when traveling alone. Therefore, even if the weight of the entire vehicle increases and the overall length increases due to the towed vehicle Vt being coupled to the host vehicle V, the entire vehicle is less likely to wobble. In addition, since the LCA is appropriately performed, the cancellation of the LCA is less likely to occur. As a result, according to this embodiment, even when the host vehicle V travels in the towing state, the LCA and LTA (i.e., the steering assist control) can be performed so that the entire vehicle changes lanes smoothly.

[0071] (Specific operation) Next, a description will be given of a specific operation of the ECU 10. The CPU of the ECU 10 is configured to repeatedly execute the routines shown in the flowcharts of Figures 4 and 5 every time a predetermined calculation time elapses while the ignition switch is in the ON position.

[0072] 4, and proceeds to step 410 to determine whether or not LCA is being executed. If the LCA start condition is already satisfied and LCA is being executed, the CPU determines "Yes" in step 410, proceeds to step 495, and temporarily ends this routine. On the other hand, if the LCA start condition is not satisfied and LCA is not being executed, the CPU determines "No" in step 410 and proceeds to step 420.

[0073] When the CPU proceeds to step 420, it executes the traction condition determination process which is the routine of FIG. 5. That is, the CPU starts the process from step 500 of FIG. 5 and proceeds to step 510 to determine whether the vehicle speed v of the host vehicle is greater than or equal to the vehicle speed threshold vth (condition 1c). If v≥vth is satisfied, the CPU determines "Yes" at step 510 (that is, determines that condition 1c is satisfied) and proceeds to step 520.

[0074] At step 520, the CPU determines whether the speed vr of the rear solid object detected based on the surrounding information is substantially the same as the vehicle speed v (that is, whether |vr - v|≤Δv is satisfied) (condition 2c). If |vr - v|≤Δv is satisfied, the CPU determines "Yes" at step 520 (that is, determines that condition 2c is satisfied) and proceeds to step 530.

[0075] At step 530, the CPU determines whether at least a part of the rear solid object that satisfies condition 2c exists within the rear region R1 (condition 3c). If at least a part of the rear solid object exists within the rear region R1, the CPU determines "Yes" at step 530 (that is, determines that condition 3c is satisfied) and proceeds to step 540.

[0076] At step 540, the CPU determines that the traction condition is satisfied and sets the value of the traction flag to 1. Then, the CPU proceeds to step 595 to temporarily end this routine.

[0077] On the contrary, if v < vth is satisfied, if |vr - v|>Δv is satisfied, or if the rear solid object does not exist within the rear region R1, the CPU determines "No" at step 510, step 520, or step 530 respectively (that is, determines that condition 1c, condition 2c, or condition 3c is not satisfied respectively) and proceeds to step 550.

[0078] In step 550, the CPU determines that the towing condition is not satisfied and sets the value of the towing flag to 0. After that, the CPU proceeds to step 595 and temporarily ends this routine.

[0079] When the CPU ends the towing condition determination process in step 595, it proceeds to step 430 in Fig. 4. In step 430, the CPU determines whether or not the LCA start condition is satisfied. If the LCA start condition is not satisfied, the CPU determines "No" in step 430, proceeds to step 495, and temporarily ends this routine. On the other hand, if the LCA start condition is satisfied, the CPU determines "Yes" in step 430, and proceeds to step 440.

[0080] In step 440, the CPU judges whether the value of the towing flag set by the towing condition judgment in step 420 is 1. If the value of the towing flag is 0, the CPU judges "No" in step 440 and proceeds to step 450. In step 450, the CPU sets the lane change time T to time T1. On the other hand, if the value of the towing flag is 1, the CPU judges "Yes" in step 440 and proceeds to step 460. In step 460, the CPU sets the lane change time T to time T2 (>T1). That is, when the towing condition is satisfied, the CPU lengthens the lane change time T compared to when the towing condition is not satisfied. More specifically, the CPU lengthens the lane change time T by lengthening a specific time Ts of the lane change time T from time Ts1 to time Ts2.

[0081] When the process of step 450 or step 460 is completed, the CPU proceeds to step 470 and executes LCA. After that, the CPU proceeds to step 495 and ends this routine. When LCA is completed, LTA is resumed and the host vehicle moves to the center position of the target lane. This completes the lane change.

[0082] Although the driving assistance device according to this embodiment has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the object of the present invention.

[0083] For example, the towing condition may be configured to be satisfied when condition 1c and condition 3c are satisfied (i.e., the towing condition does not have to include condition 2c). In this case, condition 3c may be configured to be satisfied when at least a portion of a rear three-dimensional object detected by surrounding sensor 11 is present within rear region R2. Rear region R2 may be defined, for example, as follows. -w / 2-m≦x≦w / 2+m -L-d2≦y≦-L Length d2 (the length of rear region R2 in the y-axis direction) is preferably set to a value smaller than length d1 (for example, a predetermined value within the range of 1 m to 2 m). This makes it possible to accurately determine whether or not a towed vehicle is connected to the host vehicle even if condition 2c is not included in the towing conditions. The rear region R2 is an example of a "second rear region."

[0084] In the above embodiment, when the towing condition is satisfied, the specific time Ts of the lane change time T is lengthened compared to when the towing condition is not satisfied. However, the present invention is not limited to this configuration. For example, the lane change time T may be lengthened overall. That is, the time other than the specific time Ts of the lane change time (the time from time tn2 to time tn3) may also be lengthened. Alternatively, only the time required for the execution of LCA of the lane change time T may be lengthened. However, it is desirable to lengthen the time corresponding to the section including at least a part of the section in which the host vehicle moves laterally from the original lane to the target lane in the travel trajectory. According to this configuration, the host vehicle can move more slowly through the section, and therefore the frequency of the host vehicle coupled to the towed vehicle wobbling or the cancellation of LCA when changing lanes can be reduced.

[0085] Furthermore, the first switch 15a may be configured to generate the LCA request signal when the winker lever is moved to the first position. That is, the LCA request determination time does not need to be provided.

[0086] Furthermore, the LTA and LCA may be configured to be performed by controlling the drive device 21 and the brake device 22 in addition to the steering device 23.

[0087] Furthermore, the host vehicle may be a tow truck, and the towed vehicle may be a broken-down vehicle, an accident vehicle, or a vehicle that has been parked illegally. [Explanation of symbols]

[0088] 10: driving assistance ECU, 11: surrounding sensor, 11a: camera sensor, 11b: radar sensor, 12: vehicle speed sensor, 13: driving operation state sensor, 14: setting operation device, 15: turn signal switch (turn signal SW), 21: driving device, 22: braking device, 23: steering device, 24: turn signal

Claims

1. Mounted on the vehicle, a surrounding information acquisition device that detects three-dimensional objects present around the vehicle and a marking line extending in front of the vehicle, and acquires information about the detected three-dimensional objects and marking lines as surrounding information; A vehicle speed detection device capable of detecting the speed of the vehicle; As a steering assist control for assisting a steering operation of a driver of the vehicle, a lane keeping assist control for assisting the steering operation so that a traveling position of the vehicle is maintained at a predetermined position in a lane width direction of a lane based on the surrounding information, and a lane change assist control for assisting the steering operation so that the vehicle moves from an original lane in which the vehicle is currently traveling to a target lane adjacent to the original lane based on the surrounding information, The lane change assist control is started when a predetermined start condition including the lane keeping assist control being executed is satisfied, and is ended when the movement to the target lane is completed, When the lane change assist control is ended, the lane keeping assist control is resumed. A control unit configured as described above. Equipped with When the lane change time is defined as a time required for the vehicle to move from a predetermined position in the lane width direction of the original lane to a predetermined position in the lane width direction of the target lane by the lane change assist control and the lane keeping assist control, The control unit when the speed of the vehicle is equal to or greater than a predetermined speed threshold, the speed of a rear three-dimensional object that is a three-dimensional object detected behind the vehicle by the surrounding information acquisition device is substantially the same as the speed of the vehicle, and at least a portion of the rear three-dimensional object is present within a predetermined first rear area defined behind the vehicle, it is determined that a towing condition that is established when a towed vehicle is coupled to the vehicle is established, When the towing condition is satisfied in a case where the start condition of the lane change assist control is satisfied, a specific time, which is a time required for the vehicle to move from the original lane to the target lane in the lane width direction, is lengthened among the lane change time, and a section of a travel trajectory, which is a trajectory along which a lane change is performed, corresponding to the specific time is lengthened in the extension direction of the original lane and the target lane, compared to when the towing condition is not satisfied. It is structured as follows: The first rear region is defined by setting an origin at the center of the front bumper of the vehicle, setting an x-axis with a rightward direction as a positive direction, and a y-axis with a forward direction as a positive direction, and defining w as the vehicle width, m as a predetermined margin, L as the length of the vehicle in the front-rear direction, and d1 as a predetermined length, and then expressing the following equation: -w / 2-m≦x≦w / 2+m -L-d1≦y≦-L is defined by The margin m and the length d1 are set to values ​​such that a following vehicle traveling at substantially the same speed as the vehicle or another vehicle traveling in an adjacent lane cannot enter the first rear area. Driving assistance device.

2. The driving assistance device according to claim 1, The control unit When the vehicle has finished crossing the dividing line at the boundary between the original lane and the target lane due to the lane change assist control, it is determined that the vehicle has completed moving to the target lane, and the lane change assist control is terminated. It was configured as follows: Driving assistance device.

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