Driving assistance devices for vehicles

Abstract

The present invention provides a driving assistance device for a vehicle capable of making appropriate lane changes without causing discomfort to passengers. When a driving_ECU (22) determines the necessity of lane change based on a preset condition during driving in a second driving assistance mode, a lane change route is set for causing the vehicle to change lanes from the vehicle's driving lane to an adjacent lane. When lane change control accompanied by steering control is performed based on the lane change route, if the lane change is accompanied by a preset urgency, a threshold is set to a threshold (2) higher than a threshold (1) as a reference value, and the lane change is prohibited when the maximum steering speed of the steering to be performed based on the lane change route is greater than the set threshold.

Description

Technical Field

[0001] The present invention relates to a driving assistance device for a vehicle that performs automatic driving control including lane change control. Background Art

[0002] In recent years, in vehicle driving assistance devices, technologies for performing lane keeping control to keep the host vehicle in a lane and technologies for performing automatic driving control including lane change control to change the host vehicle to an adjacent lane have been proposed.

[0003] In such an automatic driving control, as a technology for changing lanes from the current driving lane of the host vehicle to the adjacent target lane, for example, the following technology is disclosed in Patent Document 1: the final location of the target trajectory (the location where the lane change of the host vehicle ends) is calculated based on the vehicle speed of the host vehicle and / or the time required for lane change, and the driving route that reaches the final location after the desired time from the starting location of the lane change is set as the target route (target driving route), and the lane change of the host vehicle to the target lane is assisted according to the target route. In addition, Patent Document 1 also discloses the following technology: the final location is recalculated according to the change of the driving state of the vehicle existing in the target lane, and the target driving route is recalculated based on the recalculated final location.

[0004] However, in the driving assistance device as described above, when changing lanes as part of the automatic driving control, in order to suppress the generation of a sudden yaw moment, etc., and to achieve the lane change in a manner that does not make the driver and / or other passengers feel uneasy, a limit (upper limit) is usually set on the steering speed of the automatic steering. In addition, in such a driving assistance device, when it is determined based on the steering speed that it is difficult to change lanes and it is determined that it is difficult to continue driving based on the automatic driving, an automatic retreat mode for retreating the vehicle to the shoulder of the road is executed.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2014-61792 Summary of the invention

[0008] Technical issues

[0009] However, in scenarios where lane changing is necessary, such as to avoid an obstacle on the target driving route, even if it results in a slightly worse riding experience, giving up on lane changing and executing automatic avoidance mode may cause discomfort to the passengers.

[0010] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a driving assistance device for a vehicle that can perform appropriate lane changes without causing discomfort to passengers.

[0011] Technical Solution

[0012] A driving assistance device for a vehicle according to an embodiment of the present invention comprises: a driving environment recognition unit that recognizes the driving environment of the vehicle; a target driving route setting unit that sets a target driving route in the lane where the vehicle is traveling based on the driving environment; a driving control unit that has an automatic driving mode, and the automatic driving mode performs driving assistance control that does not require the driver to steer the vehicle based on the target driving route; a lane change route setting unit that sets a lane change route for causing the vehicle to change lanes from the lane where the vehicle is traveling to an adjacent lane when the necessity of a lane change is determined based on a pre-set condition during driving in the automatic driving mode; and a lane change control unit that performs lane change control accompanied by steering control based on the lane change route, wherein the vehicle The driving assistance device of the vehicle is configured to set a limit on the steering speed when the lane is set by using the lane change route setting mechanism so that the maximum steering speed does not exceed a threshold value. The driving assistance device of the vehicle also has a lane change urgency determination mechanism, and the lane change urgency determination mechanism determines the urgency of the lane change based on the information of the driving environment recognition mechanism. The driving assistance device of the vehicle changes the threshold of the maximum steering speed when the urgency is determined to be high by the lane change urgency determination mechanism to a second threshold value greater than the first threshold value, and the first threshold value is the threshold of the maximum steering speed when the urgency is determined to be not high. Moreover, when the route is set by using the lane change route setting mechanism, the driving assistance device of the vehicle suppresses or prohibits the execution of the lane change when the maximum steering speed exceeds the second threshold value.

[0013] Effects of the Invention

[0014] According to the driving assistance device for a vehicle of the present invention, it is possible to perform an appropriate lane change without causing discomfort to the occupant. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the driving assistance device.

[0016] Figure 2 1 is a flowchart showing a lane change execution determination procedure in the automatic driving mode.

[0017] Figure 3 : is a flowchart showing a lane change permission determination subroutine.

[0018] Figure 4This is an explanatory diagram showing an example of a target driving route to be set when changing lanes.

[0019] Figure 5 This is an explanatory diagram showing an example of a target driving route to be set when changing lanes.

[0020] Figure 6 This is an explanatory diagram illustrating an example of how the steering wheel angle changes with time when changing lanes.

[0021] Figure 7 is a graph showing the threshold value of the steering speed.

[0022] Figure 8 It is a conversion map for conversion to each driving mode.

[0023] Explanation of symbols

[0024] 1… Driving assistance device 10… In-vehicle communication line 11… Positioning unit (driving environment recognition mechanism) 12… Positioning calculation unit 12a… Vehicle position estimation unit 12b… Map information acquisition unit 13… Front and rear acceleration sensors 14… Wheel speed sensor 15… Gyro sensor 16… GNSS receiver 18… High-precision road map database 21… Camera unit (driving environment recognition mechanism) 21a… Main camera 21b… Sub-camera 21d… Driving environment recognition unit 211, 21r… Side rear cameras 22… Driving_ECU (target driving route setting mechanism, driving control mechanism, lane change route setting mechanism, lane change control mechanism, and lane change urgency determination mechanism) 23… E / G_ECU 24… PS_ECU 25… BK_ECU 26…Throttle actuator 27…Electric power steering motor 28…Brake actuator 31…Automatic driving switch 32…Steering wheel touch sensor 33…Steering torque sensor 34…Brake sensor 100…Own vehicle 101…Parallel vehicle 102…Obstacle 7 DETAILED DESCRIPTION

[0025] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 This is a schematic diagram of the driving assistance device. Figure 2 is a flowchart showing a lane change execution determination procedure in the automatic driving mode, Figure 3 is a flowchart showing a lane change permission determination subroutine, Figure 4 , Figure 5 This is an explanatory diagram showing an example of a target driving route to be set when changing lanes. Figure 6 This is an illustration showing how the steering wheel angle changes over time when changing lanes. Figure 7 is a graph showing the threshold value of the steering speed, Figure 8It is a conversion map for conversion to each driving mode.

[0026] Hereinafter, one embodiment of the present invention will be described based on the drawings. Figure 1 The driving assistance device 1 shown is mounted on a vehicle such as an automobile (this vehicle). The driving assistance device 1 has a positioning unit 11 and a camera unit 21 as sensor units (driving environment recognition means) for recognizing the driving environment outside the vehicle, and these two units 11 and 21 constitute a completely independent multiple system that is independent of each other. In addition, the driving assistance device 1 has a driving control unit (hereinafter referred to as "driving_ECU") 22, an engine control unit (hereinafter referred to as "E / G_ECU") 23, a power steering control unit (hereinafter referred to as "PS_ECU") 24, and a brake control unit (hereinafter referred to as "BK_ECU") 25, and these control units 22 to 25 are connected to the positioning unit 11 and the camera unit 21 via an in-vehicle communication line 10 such as CAN (Controller Area Network).

[0027] The positioning unit 11 estimates the position of the vehicle on the road map, and includes a positioning calculation unit 12 that estimates the position of the vehicle.

[0028] Connected to the input side of the positioning operation unit 12 are sensors required for inferring the position of the vehicle (own vehicle position), such as a front and rear acceleration sensor 13 for detecting the front and rear acceleration of the vehicle, a wheel speed sensor 14 for detecting the rotation speed of the front, rear, left and right wheels, a gyro sensor 15 for detecting the angular velocity or angular acceleration of the vehicle, and a GNSS receiver 16 for receiving positioning signals sent from multiple positioning satellites.

[0029] In addition, the positioning operation unit 12 is connected to a high-precision road map database 18 as a storage device. The high-precision road map database 18 is a large-capacity storage medium such as an HDD, and stores high-precision road map information (dynamic map). The high-precision road map information has lane width data, lane center position coordinate data, lane travel azimuth data, speed limit, etc. as lane data required for automatic driving. The lane data is stored at intervals of several meters for each lane on the road map.

[0030] The positioning calculation unit 12 includes a vehicle position estimation unit 12 a that estimates the position of the vehicle, and a map information acquisition unit 12 b .

[0031] The map information acquisition unit 12b acquires route map information from the current location to the destination from the map information stored in the high-precision road map database 18 based on, for example, the destination set by the driver during automatic driving. In addition, the map information acquisition unit 12b sends the acquired route map information (lane data on the route map) to the vehicle position estimation unit 12a. The vehicle position estimation unit 12a acquires the position coordinates of the vehicle based on the positioning signal received by the GNSS receiver 16. In addition, the vehicle position estimation unit 12a matches the acquired position coordinate map with the route map information to estimate the vehicle position on the road map and determine the driving lane, and acquires the road curvature of the center of the driving lane stored in the road map data.

[0032] In addition, when the vehicle is traveling in a tunnel or the like and is unable to receive effective positioning signals from positioning satellites due to decreased sensitivity of the GNSS receiver 16, the vehicle position estimation unit 12a switches to autonomous navigation to estimate the vehicle position on the road map. The autonomous navigation estimates the vehicle position based on the vehicle speed obtained from the wheel speed detected by the wheel speed sensor 14, the angular velocity detected by the gyro sensor 15, and the front and rear accelerations detected by the front and rear acceleration sensors 13.

[0033] The camera unit 21 has a vehicle-mounted camera (stereo camera), an image processing unit (IPU) 21c and a driving environment recognition unit 21d. The vehicle-mounted camera is fixed at the upper center of the front interior of the vehicle cabin and is composed of a main camera 21a and a sub-camera 21b arranged in left-right symmetrical positions across the center of the vehicle width.

[0034] The IPU 21c performs predetermined image processing on the front driving environment image information in front of the vehicle captured by the two cameras 21a and 21b, and generates the front driving environment image information (distance image information) including distance information obtained based on the difference between the positions of the corresponding objects.

[0035] The driving environment recognition unit 21d obtains the road curvature [1 / m] of the left and right dividing lines that divide the travel route (the travel route of the vehicle) of the vehicle and the width (lane width) between the left and right dividing lines based on the distance image information received from the IPU 21c. Various methods for obtaining the road curvature and lane width are known. For example, for the road curvature, the driving environment recognition unit 21d performs binarization processing based on the brightness difference based on the front driving environment image information to identify the left and right dividing lines, obtains the curvature of the left and right dividing lines for each predetermined interval by using the least squares curve approximation formula, and then calculates the lane width based on the difference in curvature between the two dividing lines.

[0036] Then, the driving environment recognition unit 21d obtains the road curvature of the center of the lane based on the curvature of the left and right interval lines and the lane width, and further calculates the lateral position deviation Xdiff of the vehicle, which is the lateral position deviation of the vehicle based on the center of the lane, and more precisely, the distance from the center of the lane to the center of the vehicle width direction of the vehicle. In addition, in this embodiment, the road curvature of the center of the lane is referred to as "camera curvature".

[0037] In addition, the driving environment recognition unit 21d performs predetermined pattern matching on the distance image information, and recognizes guardrails and / or curbstones and three-dimensional objects along the road. Here, in the recognition of three-dimensional objects by the driving environment recognition unit 21d, for example, the type of three-dimensional object, the distance to the three-dimensional object, the speed of the three-dimensional object, the relative speed between the three-dimensional object and the vehicle, etc. are recognized.

[0038] In addition, the camera unit 21 has side rear cameras 211 and 21r for photographing the left and right rear sides of the vehicle. After the side running environment image information of the vehicle photographed by these side rear cameras 211 and 21r is input to the IPU 21c, the IPU 21c performs predetermined image processing such as edge detection. In addition, the running environment recognition unit 21d performs predetermined pattern matching on the edge information detected in the IPU 21c, and recognizes three-dimensional objects such as parallel vehicles existing on the side of the vehicle and / or rear vehicles existing on the rear.

[0039] The vehicle position estimated by the vehicle position estimation unit 12a of the positioning operation unit 12, the vehicle lateral position deviation Xdiff obtained by the driving environment recognition unit 21d of the camera unit 21, and the three-dimensional object information are read by the driving_ECU 22. In addition, the automatic driving switch 31, the steering wheel touch sensor 32, the steering torque sensor 33, and the brake sensor 34 are connected to the input side of the driving_ECU 22 as various switches and sensors. The automatic driving switch 31 is used by the driver to switch the automatic driving (driving assistance control) on / off, the steering wheel touch sensor 32 is turned on when the driver steers (holds) the steering wheel, the steering torque sensor 33 detects the steering torque as the driver's driving operation amount, and the brake sensor 34 detects the brake stepping amount as the driver's driving operation amount.

[0040] In the travel_ECU 22 , a manual driving mode, a first driving assistance mode, a second driving assistance mode, and an evacuation mode are set as driving modes.

[0041] Here, the manual driving mode is a steering-required driving mode in which the driver needs to steer the vehicle, and is a driving mode in which the vehicle is driven according to driving operations such as steering wheel operation, acceleration operation, and braking operation performed by the driver.

[0042] In addition, the first driving assistance mode is also a steering-required driving mode that requires the driver to steer. That is, the first driving assistance mode is a so-called semi-automatic driving mode, which reflects the driving operation performed by the driver and is controlled by, for example, E / G_ECU23, PS_ECU24, BK_ECU25, etc., mainly by combining the preceding vehicle following control (AdaptiveCruise Control), lane keeping (Lane Keep Assist) control and lane departure prevention (Lane DeparturePrevention) control, so that the vehicle is driven along the target driving route.

[0043] In addition, the second driving assistance mode is an automatic driving mode, which does not require the driver to steer the steering wheel. Through the control of E / G_ECU23, PS_ECU24, BK_ECU25, etc., it mainly combines the leading vehicle following control (Adaptive Cruise Control), lane keeping (Lane Keep Assist) control and lane departure prevention (Lane Departure Prevention) control to make the vehicle travel along the target driving route.

[0044] The evasion mode is a mode in which the vehicle automatically stops at a curb, etc. when, for example, the second driving assistance mode cannot be used to continue driving and the driver cannot take over the driving operation (i.e., cannot be switched to the manual driving mode or the first driving assistance mode).

[0045] Each driving mode set in this way can be selectively switched in the driving_EUC 22.

[0046] When switching the mode, the driving_ECU22 always compares the lateral position of the vehicle position estimated by the vehicle position estimation unit 12a from the center of the lane on the road map and the lateral position of the vehicle obtained by the driving environment recognition unit 21d. Then, when the absolute value of the difference exceeds a preset threshold, it is determined that the reliability of either the vehicle position estimated by the vehicle position estimation unit 12a or the lateral position of the vehicle obtained by the driving environment recognition unit 21d has decreased, and it is determined that the system conditions for automatic driving are not met. Then, based on the determination result of whether the above system conditions are met and the input information from various switches and sensors, the driving_ECU22 performs switching control of the driving mode to be executed.

[0047] For example, Figure 8As shown, when the current driving mode is the manual driving mode, and when the system condition is satisfied and the driver has turned on the automatic driving switch 31, the driving_ECU 22 determines whether to switch to the first driving assistance mode.

[0048] In addition, when the current driving mode is the first driving assistance mode, on the premise that the system conditions are met and the automatic driving switch 31 remains in the on state, if the driver's hands-free state of releasing the steering wheel continues for more than a set time and the driver does not perform a braking operation for more than a set time, the driving_ECU22 determines whether to switch to the second driving assistance mode.

[0049] In addition, when the current driving mode is the first driving assistance mode, and when the system condition has become invalid, or when the driver has turned off the automatic driving switch 31, or when the driver has performed a braking operation with a brake pedaling amount greater than the set threshold value Pbth1, or when the driver has performed a steering operation with a steering torque greater than the set threshold value Psth1, the driving_ECU22 determines whether to switch to the manual driving mode.

[0050] In addition, when the current driving mode is the second driving assistance mode, on the premise that the system conditions are met and the automatic driving switch 31 remains in the on state, when the driver's brake pedaling amount is greater than the set threshold value Pbth2 (wherein the set threshold value Pbth2>the set threshold value Pbth1) and the braking operation continues for a set time or longer, or when the driver's steering torque is greater than the set threshold value Psth2 (wherein the set threshold value Psth2>Psth1) and the steering continues for a set time or longer, the driving_ECU22 determines whether to switch to the first driving assistance mode.

[0051] In addition, when the current driving mode is the second driving assistance mode, when the driver has turned off the automatic driving switch 31, or when the driver's brake pedaling amount is greater than the set threshold value Pbth3 (wherein the set threshold value Pbth3>the set threshold value Pbth2) and the braking operation continues for a set time or longer, or when the driver's steering torque is greater than the set threshold value Psth3 (wherein the set threshold value Psth3>Psth2) and the steering continues for a set time or longer, the driving_ECU22 determines whether to switch to the manual driving mode.

[0052] Furthermore, when the current driving mode is the second driving assistance mode, the driving_ECU 22 determines whether to switch to the automatic evacuation mode if the system condition has become unsatisfactory, assuming that the automatic driving switch 31 is maintained in the on state.

[0053] Here, in order to realize the above-mentioned first and second driving assistance modes, when the driving environment recognition unit 21d or the like recognizes a preceding vehicle in front of the vehicle's travel route, the driving_ECU 22 sets a target travel route based on, for example, the travel track of the preceding vehicle. In addition, when the preceding vehicle is not recognized, the driving_ECU 22 sets a target travel route based on, for example, the vehicle's travel route.

[0054] In this case, when it is necessary to change lanes from the vehicle's driving lane to an adjacent lane in order to avoid traffic congestion or obstacles such as a construction area or fallen objects in front of the vehicle's driving route, the driving_ECU22 sets the lane change route used for the lane change as a transitional target driving route.

[0055] When setting such a lane change route, the driving_ECU 22 sets the target point at, for example, a point on an adjacent lane ahead at a predetermined distance corresponding to the vehicle speed (for example, referring to Figure 4 ). The travel_ECU 22 calculates, for example, a target movement amount in the vehicle width direction and a target acceleration for causing the host vehicle 100 to reach a target point after a set time at predetermined time intervals, and sets a lane change route based on these.

[0056] At this time, for example, Figure 5 As shown in FIG. 1 , when the vehicle 100 approaches an obstacle 102, the driving_ECU 22 appropriately corrects the lane change route according to the relative distance to the obstacle, etc., in order to avoid contact between the vehicle 100 and the obstacle 102. Figure 5 In the example shown, the target point is corrected to Figure 4 The target point shown is closer to the host vehicle 100, and a lane change route is set for the host vehicle 100 to reach the target point after a set time. In the present embodiment, obstacles and the like also include preceding vehicles traveling at a relatively low speed.

[0057] Then, the travel_ECU 22 confirms that there is no parallel vehicle or the like in the adjacent lane of the lane change destination, and if there is no parallel vehicle or the like, the travel_ECU 22 performs lane change control accompanied by operation control based on the lane change line.

[0058] However, when performing lane change control, if the maximum steering speed that should be performed in the steering control for causing the host vehicle to travel along the lane change line is equal to or greater than a preset threshold, the travel_ECU 22 prohibits execution of the lane change control.

[0059] At this time, when the lane change is accompanied by a preset urgency, the threshold is changed to a second threshold (threshold 2) higher than the first threshold (threshold 1) serving as a reference value (see Figure 7 ).

[0060] Here, threshold 1 is, for example, an upper limit value of the steering speed for achieving lane change without causing the driver or passengers to feel uneasy, such as by preventing the occurrence of a sudden yaw moment, and threshold 1 is set to be smaller as the vehicle speed V is faster. In addition, threshold 2 is, for example, an upper limit value of the steering speed allowed when performing emergency evacuation steering, and is relatively larger than threshold 1, and threshold 2 is set to be smaller as the vehicle speed V is faster. In addition, these thresholds 1 and 2 are set based on experiments and / or simulations, etc.

[0061] That is, when setting a route using lane change control, the driving_ECU 22 sets a limit on the steering speed so that the maximum steering speed of the steering to be performed in the steering control does not exceed the threshold value. In this case, when it is determined that the urgency of lane change is high due to traffic congestion or obstacles such as construction areas and / or fallen objects in front of the vehicle's driving route, the driving_ECU 22 changes the threshold of the maximum steering speed to a threshold value 2 that is greater than the threshold value 1 of the maximum steering speed when it is determined that the urgency is not high. In addition, when the maximum steering speed exceeds the threshold value 2 when setting a route using the lane change control, the driving_ECU 22 suppresses or prohibits the execution of the lane change.

[0062] As described above, in the present embodiment, the travel_ECU 22 realizes the functions of a target travel route setting means, a travel control means, a lane change route setting means, a lane change control means, and a lane change urgency determination means.

[0063] A throttle actuator 26 is connected to the output side of the E / G_ECU 23. The throttle actuator 26 is a component that opens and closes a throttle valve of an electronically controlled throttle provided on a throttle of the engine, and adjusts the intake air flow rate by opening and closing the throttle valve according to a drive signal from the E / G_ECU 23, thereby generating a desired engine output.

[0064] An electric power steering motor 27 is connected to the output side of the PS_ECU 24. The electric power steering motor 27 is a component that applies a steering torque to a steering mechanism using the rotational force of the motor. During automatic driving, the electric power steering motor 27 is controlled according to a drive signal from the PS_ECU 24 to perform lane keeping control for maintaining the current driving lane and lane change control for moving the vehicle to an adjacent lane (lane change control for overtaking control, etc.).

[0065] The output side of BK_ECU25 is connected to a brake actuator 28. The brake actuator 28 is a component that adjusts the brake fluid pressure supplied to the wheel cylinders provided at each wheel. When the brake actuator 28 is driven according to a drive signal from BK_ECU25, the wheel cylinders generate a braking force on each wheel, forcibly decelerating the vehicle.

[0066] Next, follow Figure 2 1 and 2, and the lane change execution determination control executed in the driving_ECU 22 is described with reference to the flowchart of the lane change execution determination program shown in FIG. 2. The program is a process that is repeatedly executed at set intervals during the execution of the second driving assistance mode (automatic driving mode). After the program is started, the driving_ECU 22 first obtains the driving environment information of the vehicle from the positioning unit 11 and the camera unit 21 in step S101.

[0067] In the next step S102, the driving_ECU 22 determines whether it is necessary for the vehicle to change lanes from the current lane to the adjacent lane. Here, the driving_ECU 22 determines that it is necessary to change lanes when, for example, the vehicle needs to change lanes in order to travel based on the route map information from the current location to the destination, or when it is necessary to avoid a collision with an obstacle or the like in front of the vehicle's driving route.

[0068] Then, when it is determined in step S102 that a lane change is not necessary, the driving_ECU 22 maintains the driving control of the host vehicle according to the currently set target driving route and exits the process.

[0069] On the other hand, when it is determined in step S102 that a lane change is necessary, the travel_ECU 22 proceeds to step S103 to determine whether a lane change from the current lane in which the vehicle is traveling should be permitted.

[0070] The lane change permission determination is based on, for example, Figure 3 The lane change permission determination subroutine is shown in the flowchart. After the subroutine starts, the driving_ECU22 checks in step S201 whether there is an adjacent lane next to the vehicle's driving lane where lane change can be performed based on the driving environment information from the positioning unit 11 and the camera unit 21.

[0071] Then, when it is determined in step S201 that there is an adjacent lane where lane change is possible, the driving_ECU 22 proceeds to step S202 , and when it is determined in step S201 that there is no adjacent lane where lane change is possible, the driving_ECU 22 proceeds to step S204 .

[0072] When the process proceeds from step S201 to step S202 , the travel_ECU 22 checks whether there is a parallel vehicle running parallel to the host vehicle in an adjacent lane where lane change is possible.

[0073] Then, when it is determined in step S202 that there is no parallel vehicle, the travel_ECU 22 proceeds to step S207 .

[0074] On the other hand, if it is determined in step S202 that there is a parallel vehicle 101 (for example, see Figure 4 ), the driving_ECU 22 proceeds to step S203, and after instructing the host vehicle 100 to decelerate in order to move the parallel vehicle 101 relatively to a position ahead of the host vehicle 100, proceeds to step S204.

[0075] After proceeding from step S201 or step S203 to step S204 , the travel_ECU 22 checks whether there is an obstacle within a set distance ahead of the target travel route of the host vehicle.

[0076] Then, when it is determined in step S204 that there is no obstacle within the set distance ahead of the target driving route of the host vehicle, the driving_ECU 22 proceeds to step S216 .

[0077] On the other hand, if it is determined in step S204 that an obstacle 102 (for example, referring to Figure 4 ), the driving_ECU 22 proceeds to step S205, and after issuing a deceleration instruction relative to the obstacle 102 as needed, proceeds to step S206.

[0078] When the process proceeds from step S205 to step S206 , the driving_ECU 22 checks whether a collision prediction time TTC (Time To Collision) calculated by, for example, dividing the relative distance between the host vehicle 100 and the obstacle 102 ahead by the relative speed is equal to or smaller than a preset threshold value Tth.

[0079] Then, when it is determined in step S206 that the collision prediction time TTC is greater than the threshold value Tth, the travel_ECU 22 proceeds to step S216.

[0080] On the other hand, when it is determined in step S206 that the predicted collision time TTC is equal to or less than the threshold value Tth, the travel_ECU 22 determines that there is a high possibility of collision with the obstacle 102 if the host vehicle 100 continues to travel as it is, and proceeds to step S215.

[0081] When the process proceeds from step S202 to step S207 , the driving_ECU 22 checks whether there is an obstacle within a set distance ahead of the current target driving route (ie, the driving lane of the vehicle).

[0082] Then, when it is determined in step S207 that there is no obstacle within the set distance ahead of the target driving route, driving_ECU22 enters step S208. When it is determined in step S207 that there is an obstacle within the set distance ahead of the target driving route, driving_ECU22 enters step S211.

[0083] When the process proceeds from step S207 to step S208 , the travel_ECU 22 calculates a lane change route which is a transitional target travel route for the host vehicle to change lanes from the current host vehicle travel lane to an adjacent lane.

[0084] Then, if the process proceeds to step S209, the driving_ECU 22 sets the threshold value 1 (reference value: Figure 7 ) is set as a threshold value for the maximum steering speed, wherein the threshold value 1 is a threshold value when it is determined that the urgency of performing a lane change for avoiding an obstacle or the like is not high, and the maximum steering speed is the maximum steering speed for turning for a lane change to be performed according to the lane change route. As the threshold value 1, for example, it is set to a steering speed within a range in which the yaw moment or the like generated by the steering does not affect the riding comfort and is a steering speed within a range in which the host vehicle can safely perform a lane change.

[0085] In the next step S210 , the driving_ECU 22 checks whether the maximum steering speed to be performed according to the lane change route is less than a threshold value 1 .

[0086] Then, when it is determined in step S210 that the maximum steering speed is less than the threshold value 1, the driving_ECU 22 proceeds to step S217, and when it is determined in step S210 that the maximum steering speed is greater than or equal to the threshold value 1, the driving_ECU 22 proceeds to step S216.

[0087] In addition, if the process proceeds from step S207 to step S211, the driving_ECU 22 checks whether the minimum distance Lc required for lane change is less than the distance Lb from the current vehicle to the obstacle. In addition, the minimum distance Lc is, for example, a distance set in advance based on experiments and / or simulations, and the faster the vehicle speed V, the longer the minimum distance Lc.

[0088] Then, when it is determined in step S211 that the minimum distance Lc is less than the distance Lb to the obstacle, the driving_ECU 22 proceeds to step S215, and when it is determined in step S211 that the minimum distance Lc is greater than the distance Lb to the obstacle, the driving_ECU 22 proceeds to step S212.

[0089] When the process proceeds from step S211 to step S212 , the travel_ECU 22 calculates a lane change route which is a transitional target travel route for the host vehicle to change lanes from the current host vehicle travel lane to an adjacent lane.

[0090] Then, if the process proceeds to step S213, the driving_ECU 22 sets the threshold value 2 (> threshold value 1: refer to Figure 7 ) is set as a threshold value for the maximum steering speed, which is the maximum steering speed for the steering to be performed according to the lane change route. That is, the driving_ECU 22 sets a second threshold value, which is a threshold value for the maximum steering speed when it is determined that the urgency is high to avoid the obstacle ahead, etc. As this threshold value 2, for example, it is set to a steering speed within a range that can allow the vehicle to safely change lanes, although the yaw moment generated by the steering may affect the riding comfort.

[0091] In the next step S214 , the driving_ECU 22 checks whether the maximum steering speed for steering to be performed along the lane change line is less than a threshold value 2 .

[0092] Then, when it is determined in step S214 that the maximum steering speed is less than the threshold value 2, the driving_ECU 22 proceeds to step S217, and when it is determined in step S214 that the maximum steering speed is greater than or equal to the threshold value 2, the driving_ECU 22 proceeds to step S215.

[0093] When the process proceeds from step S206 , step S211 , or step S214 to step S215 , the travel_ECU 22 determines whether to switch the driving mode from the currently selected second driving assistance mode to the automatic retreat mode, and then exits the subroutine.

[0094] In addition, when the process proceeds from step S204, step S206 or step S210 to step S216, the driving_ECU 22 determines that a lane change from the current lane of the vehicle to an adjacent lane is prohibited, and then exits the subroutine.

[0095] In addition, when the process proceeds from step S210 or step S214 to step S217, the driving_ECU 22 exits the subroutine after making a determination as to whether a lane change from the current lane of the vehicle to the adjacent lane is permitted.

[0096] exist Figure 2 In the main flow of the present invention, when the process proceeds from step S103 to step S104, the travel_ECU 22 checks whether a determination is made in favor of allowing the lane change in the lane change permission determination.

[0097] Then, when it is determined in step S104 that the lane change is permitted, the driving_ECU2 proceeds to step S105, and after executing the lane change control from the current driving lane of the vehicle to the adjacent lane according to the lane change route set in step S208 or step S212, the program is exited. Thus, for example, when there is an adjacent lane where lane change is possible, and when it is determined that there is no obstacle within a set distance ahead of the driving route of the vehicle and the urgency of the lane change is not high, and when the maximum steering speed of the steering to be performed in the steering control for driving the vehicle along the calculated lane change route is less than a threshold value 1, the lane change control from the current driving lane of the vehicle to the adjacent lane is executed. In addition, for example, when there is an adjacent lane in which lane change can be performed, and when it is determined that the urgency of the lane change has increased due to the presence of an obstacle or the like within a set distance in front of the vehicle's driving route, and when the maximum steering speed to be performed in the steering control for causing the vehicle to travel along the calculated lane change route is less than threshold 2 which is greater than threshold 1, lane change control is performed from the current vehicle's driving lane to the adjacent lane.

[0098] On the other hand, if it is determined in step S104 that the lane change is not permitted, the driving_ECU 22 proceeds to step S106 to check whether a deceleration instruction has been issued for the parallel-running vehicle or the obstacle ahead in the lane change permission determination.

[0099] Then, when it is determined in step S106 that a deceleration instruction has been issued, the driving_ECU 22 proceeds to step S107 , executes deceleration control for the parallel-running vehicle or the obstacle ahead, and then exits the routine.

[0100] On the other hand, when it is determined in step S106 that no deceleration instruction has been issued, the travel_ECU 22 proceeds to step S108 to check whether a determination is made in the lane change permission determination to switch the driving mode from the second driving assistance mode to the automatic avoidance mode.

[0101] Then, when it is determined in step S108 that the decision to switch to the automatic avoidance mode is made, the driving_ECU 22 proceeds to step S109, switches the driving mode from the current second driving assistance mode to the automatic avoidance mode, and then exits the program. Thus, for example, when there is an adjacent lane where lane change is possible, and when it is determined that there is no obstacle or the like within a set distance ahead of the vehicle's driving route and the urgency of lane change is not high, and when the maximum steering speed of the steering to be performed in the steering control for driving the vehicle along the calculated lane change route is greater than or equal to threshold 1, the execution of the lane change control from the current vehicle driving lane to the adjacent lane is suppressed or prohibited. In addition, for example, when there is an adjacent lane where lane change is possible, and when it is determined that there is an obstacle or the like within a set distance ahead of the vehicle's driving route and the urgency of lane change is high, and when the maximum steering speed of the steering to be performed in the steering control for driving the vehicle along the calculated lane change route is greater than or equal to threshold 2, the execution of the lane change control from the current vehicle driving lane to the adjacent lane is suppressed or prohibited.

[0102] Furthermore, when a steering torque or a brake depression amount greater than a predetermined value by the driver is detected, the driving_ECU 22 can also switch to the first driving assist mode or the manual driving mode in order to reflect the driver's intention.

[0103] On the other hand, when it is determined in step S108 that the decision to switch to the automatic retreat mode has not been made, the travel_ECU 22 exits the routine as it is.

[0104] According to such an embodiment, when the necessity of lane change is determined based on a preset condition during driving in the second driving assistance mode, a lane change route is set for causing the vehicle to change lanes from the lane in which the vehicle is traveling to an adjacent lane. When lane change control accompanied by steering control is performed based on the lane change route, if the lane change is accompanied by a preset urgency, the threshold is set to a threshold 2 that is higher than a threshold 1 that is a reference value. If the maximum steering speed of the steering that should be performed based on the lane change route is greater than the set threshold, execution of the lane change control is suppressed or prohibited, thereby enabling appropriate lane changes to be performed without causing discomfort to the passengers.

[0105] That is, for example, in a case where the urgency of changing lanes is low, such as when there are no obstacles within a set distance ahead of the target driving route, by setting the driver's ride comfort threshold 1 as the threshold for the maximum steering speed with priority, it is possible to achieve a lane change that suppresses the generation of yaw moment, etc.

[0106] On the other hand, when there is a high urgency to change lanes, for example, when there is an obstacle within a set distance ahead of the target driving route, lane changes are given priority over ride comfort, and threshold 2, which is higher than threshold 1, is set as the threshold for the maximum steering speed. This allows the area where lane changes are permitted to be expanded (i.e., the transition to automatic evasion mode can be suppressed, etc.), allowing appropriate lane changes to be made without causing discomfort to passengers.

[0107] Therefore, in the case of emergency, even if there is a parallel vehicle 101 in the adjacent lane of the lane where the vehicle is traveling (for example, see Figure 4 ) and missed the appropriate opportunity to change lanes at a maximum turning speed less than threshold 1, if the maximum turning speed is less than threshold 2, it is possible to wait for the parallel vehicle 101 to pass (the parallel vehicle after passing is Figure 5 The vehicle is changing lanes to an adjacent lane (indicated by symbol “101′”).

[0108] also, Figure 6 (a) means that, for example, Figure 4 At the moment shown, it is assumed that there is no parallel vehicle 101 and the steering wheel angle θ changes with time when the lane change starts. Even if the steering speed (differential value of the steering wheel angle (dθ / dt)) in this case is less than the threshold 1, the lane change can be completed before crossing the obstacle 102.

[0109] on the other hand, Figure 6 (b) means that, for example, Figure 5 The change in the steering wheel angle θ over time during the lane change begins at the time shown. Figure 6 As shown by the dotted line in (b), when the steering speed is limited by threshold 1, the lane change cannot be completed before the moment of crossing the obstacle 102, so the lane change has to be abandoned. However, by changing the threshold for the steering speed to threshold 2, the lane change can be completed before that moment (that is, it can be executed without abandoning the lane change).

[0110] In addition, the present invention is not limited to the above-described embodiments, and various modifications or changes are possible, and these modifications or changes are also included in the technical scope of the present invention. For example, as a lane change accompanied by an emergency, it is not limited to when there is an obstacle in front of the target driving route, and it can also include the situation where a pedestrian suddenly appears.

Claims

1. A driving assistance device for a vehicle, characterized in that: have: A driving environment recognition mechanism, which recognizes the driving environment of the vehicle; a target driving route setting mechanism, which sets a target driving route on a driving lane of the vehicle based on the driving environment; a driving control mechanism having an automatic driving mode, wherein the automatic driving mode performs driving assistance control without requiring a driver to steer the vehicle based on the target driving route; a lane change route setting unit, which sets a lane change route for causing the host vehicle to change lanes from the host vehicle driving lane to an adjacent lane when the necessity of lane change is determined based on a preset condition during driving in the automatic driving mode; as well as a lane change control mechanism that performs lane change control accompanied by steering control based on the lane change route, The vehicle driving assistance device is configured to set a limit on the steering speed so that the maximum steering speed does not exceed a threshold value when the lane change route setting means sets the route. The vehicle driving assistance device further comprises a lane change urgency determination unit, which determines the urgency of the lane change based on the information of the driving environment recognition unit. The driving assistance device of the vehicle changes the threshold of the maximum steering speed when the lane change urgency determination unit determines that the urgency is high to a second threshold greater than a first threshold, wherein the first threshold is the threshold of the maximum steering speed when the urgency is not high, and The driving assistance device of the vehicle suppresses or prohibits execution of a lane change when the maximum steering speed exceeds the second threshold value when the lane is set by the lane change lane setting unit.

2. The driving assistance device for a vehicle according to claim 1, characterized in that: When an obstacle exists within a set distance ahead of the target driving route, the lane change urgency determination unit determines that the urgency is high and changes the threshold to the second threshold that is higher than the first threshold.

3. The vehicle driving assistance device according to claim 1 or 2, characterized in that: The first threshold value and the second threshold value are variably set according to the vehicle speed of the host vehicle.

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