Driving assistance method and driving assistance device

Abstract

A driving assistance method controls a host vehicle (1) by a controller (16) so that the host vehicle (1) travels along a target travel trajectory. In the driving assistance method, step information of a step (24) existing along a lane (20) on which the host vehicle (1) travels is acquired, and in a case where it is determined from the step information that the host vehicle (1) has crossed the step (24), the target travel trajectory is generated in such a manner that a step-crossing angle (Θs) formed by the step (24) and the target travel trajectory is greater than a threshold value (Th).

Description

TECHNICAL FIELD

[0001] The present application relates to a driving assistance method and a driving assistance device. BACKGROUND

[0002] In the following Patent Literature 1, a map data storage section is described in which step information related to a step of an entrance of a facility through which a vehicle needs to pass at the time of entering the facility from a road, and facility information related to the facility are stored in association with each other. And it is described that the position of the stored step is provided as a ground object information for entering the facility.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2019-144030 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] When a vehicle passes over a step, if the advancing direction of the vehicle is inclined with respect to the extension direction of the step, disturbance is applied to the steering wheel of the vehicle, and the advancing direction of the vehicle is deviated. Therefore, in a case where the vehicle is automatically driven along a target travel trajectory which is set in advance in automatic driving control, deviation from the target travel trajectory occurs.

[0008] An object of the present application is to reduce deviation from a target travel trajectory at the time of passing over a step in driving assistance in which a host vehicle is controlled to travel along the target travel trajectory.

[0009] TECHNICAL SOLUTION FOR SOLVING THE PROBLEM

[0010] According to one embodiment of the present application, there is provided a driving assistance method in which a host vehicle is controlled by a controller to travel along a target travel trajectory. In the driving assistance method, step information of a step present along a lane in which the host vehicle travels is acquired, and in a case where it is determined from the step information that the host vehicle passes over the step, the target travel trajectory is generated in such a manner that an angle formed by the step and the target travel trajectory, that is, a step passing angle, is greater than a threshold value.

[0011] EFFECT OF THE INVENTION

[0012] According to one embodiment of the present application, in driving assistance in which a host vehicle is controlled to travel along a target travel trajectory, deviation from the target travel trajectory at the time of passing over a step can be reduced.

[0013] The objects and advantages of the present application will be realized and attained by means of the elements and combinations particularly pointed out in the claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the application, as claimed. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a schematic configuration diagram of a driving assistance device of an embodiment.

[0015] Figure 2A is an explanatory diagram of an example of a driving assistance method of an embodiment.

[0016] Figure 2B is an explanatory diagram of an example of a driving assistance method of an embodiment.

[0017] Figure 3 is a block diagram showing an example of a functional configuration of a driving assistance device of an embodiment.

[0018] Figure 4 is an explanatory diagram of an example of calculation of a step-over angle θs.

[0019] Figure 5A is an explanatory diagram of an example of setting of a threshold value Th of a step-over angle θs.

[0020] Figure 5B is an explanatory diagram of another example of setting of a threshold value Th of a step-over angle θs.

[0021] Figure 6 is a flowchart of an example of a driving assistance method of an embodiment.

[0022] Figure 7 is a flowchart of an example of trajectory generation processing of the first embodiment.

[0023] Figure 8A is an explanatory diagram of an example of a situation in which a target speed at a time of passing a step by the host vehicle is set low.

[0024] Figure 8B is an explanatory diagram of another example of a situation in which a target speed at a time of passing a step by the host vehicle is set low.

[0025] Figure 9 is a flowchart of an example of trajectory generation processing of the second embodiment. DETAILED DESCRIPTION

[0026] (First Embodiment)

[0027] (Configuration)

[0028] Reference Signs Figure 1 The host vehicle 1 is provided with a driving assistance device 10 that performs driving assistance of the host vehicle 1. The driving assistance performed by the driving assistance device 10 can include, for example, automatic driving control that automatically drives the host vehicle 1 in a manner in which the driver does not participate, based on a driving environment around the host vehicle 1.

[0029] An example of automatic driving control performed by the drive assist device 10 can be driving control that causes the host vehicle 1 to automatically travel along a target travel trajectory set in advance in an urban area.

[0030] The drive assist device 10 includes an object sensor 11, a vehicle sensor 12, a positioning device 13, a map database 14, a communication device 15, a controller 16, and an actuator 17. The map database is referred to as "map DB" in the drawings.

[0031] The object sensor 11 includes a plurality of different types of object detection sensors, such as a laser radar or a millimeter wave radar, a camera, a LIDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging), and the like, mounted on the host vehicle 1 to detect objects around the host vehicle 1.

[0032] The vehicle sensor 12 is mounted on the host vehicle 1 to detect various information (vehicle signals) obtained from the host vehicle 1. The vehicle sensor 12 includes, for example, a vehicle speed sensor that detects the travel speed (vehicle speed) of the host vehicle 1, a wheel speed sensor that detects the rotational speed of each tire provided to the host vehicle 1, a three-axis acceleration sensor (G sensor) that detects the three-axis acceleration (including deceleration) of the host vehicle 1, a steering angle sensor that detects the steering angle (including the steering angle), a gyro sensor that detects the angular velocity generated in the host vehicle 1, a yaw rate sensor that detects the yaw rate, an accelerator sensor that detects the accelerator opening degree of the host vehicle, and a brake sensor that detects the brake operation amount performed by the driver.

[0033] The positioning device 13 includes a global positioning system (GNSS) receiver that receives radio waves from a plurality of navigation satellites to measure the current position of the host vehicle 1. The GNSS receiver can be, for example, a global positioning system (GPS) receiver or the like. The positioning device 13 can also be, for example, an inertial navigation device.

[0034] The map database 14 can store high-precision map data (hereinafter, simply referred to as "high-precision map") suitable as a map for automatic driving. The high-precision map is map data that has higher precision than navigation map data (hereinafter, simply referred to as "navigation map"), and includes lane-unit information that is more detailed than road-unit information.

[0035] For example, the high-precision map includes lane node information that indicates reference points on a lane reference line (for example, a line in the center of a lane), and information on lane links that indicates the shape of a lane section between lane nodes, as the lane-unit information.

[0036] The information of the lane node includes an identification number, position coordinates, the number of connected lane links, and identification numbers of the connected lane links of the lane node. The information of the lane link includes an identification number of the lane link, a type of the lane, a width of the lane, a type of a lane boundary line, a shape of the lane, a shape of a lane division line, and a shape of a lane reference line. The high-precision map further includes a type and position coordinates of a signal, a stop line, a sign, a building, a utility pole, a curb, a pedestrian crossing, and the like, which exist on or near the lane, and information of the above-mentioned objects, such as an identification number of a lane node and an identification number of a lane link corresponding to the position coordinates of the objects

[0037] The high-precision map can determine the lane in which the host vehicle 1 travels in the travel route because it includes the node and link information of the lane unit. The high-precision map has coordinates that can express the position in the extension direction and the width direction of the lane. The high-precision map has coordinates (for example, precision, latitude, and altitude) that can express the position in a three-dimensional space, and the lane or the above-mentioned objects can also be described as a shape in the three-dimensional space.

[0038] The communication device 15 performs wireless communication between the communication device and a communication device outside the host vehicle 1. The communication method by the communication device 15 can be, for example, wireless communication realized by a public mobile phone network, inter-vehicle communication, road-to-vehicle communication, or satellite communication.

[0039] The controller 16 is an electronic control unit (ECU: Electronic Control Unit) that performs driving assistance control of the host vehicle 1. The controller 16 includes a processor 18 and peripheral components such as a storage device 19. The processor 18 can be, for example, a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit).

[0040] The storage device 19 can have a semiconductor storage device, a magnetic storage device, an optical storage device, or the like. The storage device 19 can include a register, a cache memory, a memory such as a ROM (Read Only Memory) and a RAM (Random Access Memory) serving as a main storage device.

[0041] The functions of the controller 16 described below are realized, for example, by the processor 18 executing a computer program stored in the storage device 19.

[0042] Furthermore, the controller 16 can also be formed of dedicated hardware for performing each information processing described below.

[0043] For example, the controller 16 can also have a functional logic circuit set in a general-purpose semiconductor integrated circuit. For example, the controller 16 can also have a programmable logic device such as a field-programmable gate array (FPGA: Field-Programmable Gate Array) or the like.

[0044] The actuator 17 operates the steering wheel, the accelerator opening degree, and the brake device of the host vehicle in accordance with the control signal from the controller 16, to generate the vehicle behavior of the host vehicle. The actuator 17 has a steering actuator, an accelerator opening degree actuator, and a brake control actuator. The steering actuator controls the steering direction and the steering amount of the steered wheels of the host vehicle.

[0045] The accelerator opening degree actuator controls the accelerator opening degree of the host vehicle. The brake control actuator controls the braking action of the brake device of the host vehicle 1.

[0046] Next, an example of the driving assist control performed by the controller 16 will be described. Referring to Figure 2A and Figure 2B . Reference sign 20 denotes a lane in which the host vehicle 1 travels, and reference signs 21 and 22 denote lane division lines that show the boundaries of the lane 20. In the example of the present specification, the lane division line 21 is a lane outer side line of the lane 20, and the lane division line 22 is a lane boundary line. These lane division lines 21 and 22 are examples of the "travel road boundary" recited in the claims. The travel road boundary is not limited to the lane division line, and can be, for example, a ground object such as a curb or a guardrail, or a shoulder.

[0047] A passageway 23 is connected to the lane 20 in the lateral direction of the lane 20, and a step 24 extends in parallel with the lane 20 between the lane 20 and the passageway 23. The passageway 23 can be a passageway that intrudes into, for example, a facility or a private land, or the like. The passageway 23 need not be a passageway that is explicitly provided, and can be, for example, a part of a sidewalk or the like that exists between an entrance of a facility or a private land or the like and the lane 20.

[0048] At present, it is assumed that the controller 16 that performs automatic driving control generates a target travel trajectory 25 that deviates from the lane 20 and intrudes into the passageway 23 as shown in Figure 2A The host vehicle 1 that travels along the target travel trajectory 25 passes over the step 24 and intrudes into the passageway 23.

[0049] An angle θs formed by the advancing direction of the host vehicle 1 at the time of passing over the step 24 and the extending direction of the step 24 is determined by the angle formed by a straight line parallel to the step 24 and the target travel trajectory 25, that is, the angle at which the step 24 and the target travel trajectory 25 intersect. Hereinafter, the angle θs at which the step 24 and the target travel trajectory 25 intersect will be expressed as a "step passing angle".

[0050] In a case where the step-crossing angle θs is less than 90 degrees, that is, in a case where the advancing direction of the host vehicle 1 is inclined with respect to the extending direction of the step 24, disturbance around the steering axis is applied to the steered wheels of the host vehicle 1 that cross the step 24. In the present specification, the steered wheels refer to wheels that are steered by a steering mechanism.

[0051] The greater the step-crossing angle θs deviates from 90 degrees, the greater the disturbance. If a large disturbance is applied to the steered wheels, it is possible that the actual steering angle deviates from the target steering angle set in accordance with the target travel trajectory 25, the host vehicle 1 deviates from the target travel trajectory 25, and the host vehicle 1 easily approaches the surrounding obstacles.

[0052] Therefore, the controller 16 generates the target travel trajectory in such a way that the step-crossing angle θs is greater than a prescribed threshold value Th in a case where the target travel trajectory that crosses the step 24 is generated.

[0053] Figure 2B An example of the target travel trajectory 27 that is generated in such a way that the step-crossing angle θs is greater than a prescribed threshold value Th is shown in FIG. 8. By generating the target travel trajectory 27 in such a way that the step-crossing angle θs is greater than a prescribed threshold value Th, the host vehicle 1 is able to cross the step 24 at an angle close to 90 degrees.

[0054] Thus, the disturbance around the steering axis applied to the steered wheels when crossing the step 24 is reduced, and it is possible to reduce the deviation from the target travel trajectory 27. As a result, it is possible to mitigate the approach to the obstacles caused by the deviation from the target travel trajectory 27.

[0055] Further, in the present specification, a case where the step 24 exists between the lane 20 and the passageway 23 is described, but the present application is not limited thereto. The present application can be widely applied to a case where the target travel trajectory that crosses the step 24 is generated in automatic driving control.

[0056] Next, the functions of the controller 16 will be described in detail with reference to Figure 3 The controller 16 has an object detection section 30, a host vehicle position estimation section 31, a map acquisition section 32, a detection integration section 33, an object tracking section 34, a map-internal position calculation section 35, a driving action plan determination section 36, a drivable area determination section 37, a target travel trajectory generation section 38, a step determination section 39, a step-crossing angle calculation section 40, a regeneration determination section 41, and a vehicle control section 42.

[0057] The object detection section 30 detects the position, posture, size, speed, and the like of an object, such as a vehicle or a motorcycle, a pedestrian, an obstacle, and the like, in the vicinity of the host vehicle 1, based on the detection signal of the object sensor 11. The object detection section 30, for example, outputs the detection result that represents the two-dimensional position, posture, size, speed, and the like of the object in a zenithal view (also referred to as a top view) that looks down on the host vehicle 1 from the sky.

[0058] The own vehicle position estimation section 31 measures the absolute position of the own vehicle 1, i.e., the position, posture, and speed of the own vehicle 1 with respect to a prescribed reference point, based on the measurement results using the positioning device 13, the mileage from the detection results of the vehicle sensors 12.

[0059] The map acquisition section 32 acquires map information indicating the structure of the road on which the own vehicle 1 travels from the map database 14. The map acquisition section 32 can also acquire map information from an external map data server using the communication device 15.

[0060] The detection integration section 33 integrates the plurality of detection results obtained by the object detection section 30 from the plurality of object detection sensors, and outputs one detection result to each object.

[0061] Specifically, the most reasonable behavior of the object, which is the least erroneous, is calculated based on the behavior of the object obtained from each of the object detection sensors, taking into account the error characteristics and the like of each of the object detection sensors.

[0062] Specifically, a more accurate detection result is obtained by comprehensively evaluating the detection results acquired by the plurality of sensors using a known sensor fusion technique.

[0063] The object tracking section 34 tracks the objects detected by the object detection section 30. Specifically, based on the detection result integrated by the detection integration section 33, the identity verification (association) of the objects between different times is performed based on the behavior of the objects output at different times, and the behavior such as the speed of the objects is predicted based on the association.

[0064] The in-map position calculation section 35 calculates the position and posture of the own vehicle 1 on the map based on the absolute position of the own vehicle 1 obtained by the own vehicle position estimation section 31 and the map information acquired by the map acquisition section 32.

[0065] The driving action plan determination section 36 determines the rough driving action of the own vehicle 1 to be executed by the driving assist device 10 based on the detection result obtained by the detection integration section 33 and the object tracking section 34 and the position of the own vehicle 1 specified by the in-map position calculation section 35.

[0066] The driving action plan determination section 36 determines the driving action such as the stop, temporary stop, travel speed, deceleration, acceleration, route change, right turn, left turn, straight travel, lane change in a merging section or a multi-lane, lane maintenance, overtaking, and response to an obstacle of the own vehicle 1.

[0067] The driving action plan determination section 36 generates a path space map that represents the presence or absence of a path or an object in the vicinity of the host vehicle 1 and a risk map that numerically represents the degree of danger of a travel region, based on the position and posture of the host vehicle 1 estimated by the in-map position calculation section 35, the positions and postures of the objects in the vicinity of the host vehicle 1, and the high-precision map. The driving action plan determination section 36 generates a driving action plan for the host vehicle 1 based on the path space map and the risk map.

[0068] The drivable region determination section 37 determines a drivable region in which the host vehicle 1 can travel, based on the driving action plan determined by the driving action plan determination section 36, the motion characteristics of the host vehicle 1, and the path space map.

[0069] The target travel trajectory generation section 38 generates candidates of a travel trajectory and a speed profile for the host vehicle 1 to travel, based on the driving action determined by the driving action plan determination section 36 and the drivable region determined by the drivable region determination section 37.

[0070] The target travel trajectory generation section 38 evaluates the future risk of each candidate based on the risk map, selects the best travel trajectory and speed profile, and sets them as the target travel trajectory and the target speed profile for the host vehicle 1 to travel.

[0071] Reference Figure 2A In the case where the target travel trajectory generation section 38 generates the target travel trajectory 25 that makes the host vehicle 1 turn, the target travel trajectory generation section 38 gradually increases the curvature of the target travel trajectory 25 to a maximum curvature and then gradually decreases it.

[0072] For example, the target travel trajectory generation section 38 generates the target travel trajectory 25 that imitates a clothoid curve or a spline curve. However, the target travel trajectory 25 is not limited to a curve calculated by such a known formula. The target travel trajectory 25 can be a curve whose curvature gradually increases to a maximum curvature and then gradually decreases.

[0073] The target travel trajectory generation section 38 can determine the rate of change of the curvature of the target travel trajectory in accordance with a specific parameter. Hereinafter, the parameter that determines the rate of change of the curvature of the target travel trajectory will be referred to as a "curvature easing parameter". The larger the curvature easing parameter, the more the target travel trajectory 25 is generated to have a more gradual change in curvature. The smaller the curvature easing parameter, the more the target travel trajectory 25 is generated to have a more abrupt change in curvature.

[0074] Reference Figure 3 The step determination section 39 acquires step information on the step 24 that exists in parallel with the lane 20. For example, the step determination section 39 can also acquire the step information based on the image recognition result of the captured image of the camera. In addition, the step determination section 39 can also acquire the step information based on the detection result of the laser radar or the millimeter wave radar, the LIDAR.

[0075] The step determination portion 39 can acquire, for example, the position, height, and inclination (inclination angle of the upper surface of the step 24 with respect to the road surface or horizontal surface of the lane 20) of the step 24 as the step information.

[0076] In addition, the step determination portion 39 can acquire, for example, the step information of the step 24 provided at the boundary between the public road and the private land existing on the target travel trajectory 25 by detecting the boundary between the public road and the private land based on the map information of the map database 14.

[0077] In addition, the step determination portion 39 can acquire, for example, the step information of the step 24 existing on the target travel trajectory 25 based on the travel history stored when the host vehicle 1 or other vehicles actually travel.

[0078] The step passing angle calculation portion 40 determines whether the target travel trajectory 25 passes over the step 24 (whether the target travel trajectory 25 crosses the step 24). In the case where the target travel trajectory 25 passes over the step 24, the step passing angle θs is calculated. Referring to Figure 4 The symbols 2FL and 2FR denote the steering wheels of the host vehicle 1, and the symbols 2RL and 2RR denote the wheels other than the steering wheels. In the example of the present specification, the steering wheels 2FL and 2FR are the left and right front wheels, respectively, and the wheels 2RL and 2RR are the left and right rear wheels, respectively.

[0079] The step passing angle calculation portion 40 calculates the step passing angle (the step passing angle at which the step 24 and the target travel trajectory 25 cross) θs of the straight line parallel to the step 24 and the target travel trajectory 25 using the trajectory through which the center position C of the axle 3 of the steering wheels 2FL and 2FR passes as the target travel trajectory 25.

[0080] In this way, by calculating the angle of the straight line parallel to the step 24 and the trajectory through which the center position C of the axle 3 of the steering wheels 2FL and 2FR passes as the step passing angle θs, the angle of the direction of the steering wheels 2FL and 2FR and the direction in which the step 24 extends can be more appropriately calculated.

[0081] Referring to Figure 3 The regeneration determination portion 41 determines whether to regenerate the target travel trajectory based on the step passing angle θs calculated with respect to the target travel trajectory 25 generated by the target travel trajectory generation portion 38.

[0082] In the case where the step passing angle θs is equal to or less than a predetermined threshold value Th, the regeneration determination portion 41 determines to regenerate the target travel trajectory. In the case where the step passing angle θs is greater than the predetermined threshold value Th, the regeneration determination portion 41 determines not to regenerate the target travel trajectory. The regeneration determination portion 41 outputs the determination result to the target travel trajectory generation portion 38.

[0083] Further, the regeneration determination portion 41 can also dynamically change the threshold value Th. For example, the regeneration determination portion 41 can set a varying threshold value Th in accordance with the step information of the step 24. For example, the higher the step 24, the greater the threshold value Th that the regeneration determination portion 41 sets. For example, the greater the inclination of the step 24, the greater the threshold value Th that the regeneration determination portion 41 sets.

[0084] For example, the regeneration determination portion 41 can also set a varying threshold value Th in accordance with the flat ratio or the outer diameter of the tire of the host vehicle 1. For example, the lower the flat ratio of the tire, the greater the threshold value Th that the regeneration determination portion 41 sets. For example, the smaller the outer diameter of the tire, the greater the threshold value Th that the regeneration determination portion 41 sets.

[0085] In addition, the regeneration determination portion 41 can acquire obstacle information of obstacles around the host vehicle 1 from the object sensor 11. For example, in the situation shown in FIG. 7, there are the pillars 40a and 40b as obstacles. Figure 5A

[0086] In the case where the obstacles 40a and 40b exist near the predetermined target travel trajectory 27 on which the host vehicle 1 travels after passing over the step 24, the regeneration determination portion 41 can set a greater threshold value Th.

[0087] Referring to FIG. 8, the map database 14 can store the lane width Wl of the lane 23 on which the host vehicle 1 travels after passing over the step 24. Figure 5B It can be that the narrower the lane width Wl of the lane 23 on which the host vehicle 1 travels after passing over the step 24, the greater the threshold value Th that the regeneration determination portion 41 sets. The information of the lane width Wl can be acquired from the map database 14, for example.

[0088] Referring to FIG. 8, the map database 14 can store the lane width Wl of the lane 23 on which the host vehicle 1 travels after passing over the step 24. Figure 3 In the case where the regeneration determination portion 41 determines to regenerate the target travel trajectory, the target travel trajectory generation portion 38 regenerates the target travel trajectory.

[0089] In regenerating the target travel trajectory, the target travel trajectory generation portion 38 regenerates the target travel trajectory in such a manner that the step pass angle θs of the regenerated target travel trajectory increases.

[0090] For example, the target travel trajectory generation portion 38 regenerates the target travel trajectory in such a manner that the step pass angle θs increases by reducing the curvature easing parameter of the target travel trajectory that turns the host vehicle 1 toward the step 24.

[0091] On the other hand, in the case where the regeneration determination portion 41 determines not to regenerate the target travel trajectory, the target travel trajectory generation portion 38 outputs the target travel trajectory and the target speed profile to the vehicle control portion 42. ​

[0092] Thus, because the target travel trajectory generating section 38 repeats the regeneration of the target travel trajectory until the step-crossing angle θs is greater than the threshold value Th, the target travel trajectory in which the step-crossing angle θs is greater than the threshold value Th is generated.

[0093] Further, the target travel trajectory generating section 38 can also set the target speed curve in such a manner that the target speed at the time when the host vehicle 1 crosses the step 24 is a predetermined slow speed (for example, 10 (km / h)) or less.

[0094] In addition, the target travel trajectory generating section 38 can also dynamically change the target speed at the time when the host vehicle 1 crosses the step 24.

[0095] For example, the target travel trajectory generating section 38 can also set the target speed curve in such a manner that the target speed at the time when the host vehicle 1 crosses the step 24 varies according to the step information of the step 24.

[0096] For example, the higher the step 24, the lower the target speed at the time when the host vehicle 1 crosses the step 24 is set by the target travel trajectory generating section 38. In addition, for example, the greater the inclination of the step 24, the lower the target speed at the time when the host vehicle 1 crosses the step 24 is set by the target travel trajectory generating section 38.

[0097] For example, the target travel trajectory generating section 38 can also set the target speed curve in such a manner that the target speed at the time when the host vehicle 1 crosses the step 24 varies according to the flatness of the tire of the host vehicle 1 or the outer diameter of the tire. For example, the lower the flatness, the lower the target speed at the time when the host vehicle 1 crosses the step 24 is set by the target travel trajectory generating section 38. In addition, for example, the smaller the outer diameter of the tire, the lower the target speed at the time when the host vehicle 1 crosses the step 24 is set by the target travel trajectory generating section 38.

[0098] In addition, the target travel trajectory generating section 38 can also acquire obstacle information of obstacles around the host vehicle 1 from the object sensor 11.

[0099] Referring to Figure 5A In the case where obstacles 40a and 40b exist in the vicinity of the predetermined target travel trajectory 27 along which the host vehicle 1 travels after crossing the step 24, the target speed curve can be set in such a manner that the target speed at the time when the host vehicle 1 crosses the step 24 becomes lower.

[0100] Referring to Figure 5B The target travel trajectory generating section 38 can set the target speed curve in such a manner that the narrower the lane width Wl of the lane 23 along which the host vehicle 1 travels after crossing the step 24, the lower the target speed at the time when the host vehicle 1 crosses the step 24.

[0101] Further, the target travel trajectory generation section 38 can set the target speed curve in a manner that the target speed at the timing when the host vehicle 1 passes the step 24 changes according to the step passing angle θs.

[0102] For example, the smaller the step passing angle θs, the lower the target speed at the timing when the host vehicle 1 passes the step 24 is set by the target travel trajectory generation section 38.

[0103] Referring to Figure 3 The vehicle control section 42 drives the actuator 17 so that the host vehicle 1 travels at a speed that follows the target speed curve output from the target travel trajectory generation section 38.

[0104] (Action)

[0105] Next, referring to Figure 6 , an example of the action of the driving assist device 10 according to the embodiment will be described.

[0106] In step S1, the object detection section 30 detects the position, posture, size, speed, and the like of the objects around the host vehicle 1 using a plurality of object detection sensors.

[0107] In step S2, the detection integration section 33 integrates a plurality of detection results obtained from the plurality of object detection sensors respectively, and outputs one detection result for each object. The object tracking section 34 tracks each object detected and integrated, and predicts the behavior of the objects around the host vehicle 1.

[0108] In step S3, the host vehicle position estimation section 31 measures the position, posture, and speed of the host vehicle 1 with respect to a prescribed reference point based on the measurement result using the positioning device 13, and the mileage from the detection result of the vehicle sensor 12.

[0109] In step S4, the map acquisition section 32 acquires map information indicating the structure of the road on which the host vehicle 1 travels.

[0110] In step S5, the in-map position calculation section 35 estimates the position and posture of the host vehicle 1 on the map based on the position of the host vehicle 1 measured in step S3, and the map data acquired in step S4.

[0111] In step S6, the driving action plan determination section 36 determines the driving action of the host vehicle 1 to be executed by the driving assist device 10 based on the detection result (the behavior of the objects around the host vehicle 1) obtained in step S2 and the position of the host vehicle 1 specified in step S5.

[0112] In step S7, the travelable region determining section 37, the target travel trajectory generating section 38, the step determining section 39, the step passing angle calculating section 40, and the regeneration determining section 41 execute a trajectory generating process for generating the target travel trajectory of the host vehicle 1.

[0113] Referring to Figure 7 The trajectory generating process of the first embodiment will be described. In step S10, the travelable region determining section 37 determines a travelable region in which the host vehicle 1 can travel, based on the motion characteristics of the host vehicle 1, the path space map, in accordance with the driving action plan determined by the driving action plan determining section 36. The target travel trajectory generating section 38 generates the target travel trajectory and the target speed profile, based on the driving action determined by the driving action plan determining section 36 and the travelable region determined by the travelable region determining section 37.

[0114] In step Sll, the step determining section 39 acquires step information of the step 24 existing in parallel with the lane 20.

[0115] In step S12, the step passing angle calculating section 40 determines whether the target travel trajectory 25 passes over the step 24 (whether the target travel trajectory 25 crosses the step 24). In the case where the target travel trajectory 25 passes over the step 24, the step passing angle θs is calculated.

[0116] The regeneration determining section 41 determines whether the step passing angle θs is below a prescribed threshold value Th. In the case where the step passing angle θs is below the prescribed threshold value Th (step S12: Y), the process proceeds to step S13.

[0117] In step S13, the target travel trajectory generating section 38 reduces the curvature easing parameter of the target travel trajectory that turns the host vehicle 1 toward the step 24.

[0118] In step S14, the target travel trajectory generating section 38 regenerates the target travel trajectory that passes over the step 24 using the curvature easing parameter set in step S13. Thereafter, the process returns to step S12.

[0119] On the other hand, in step S12, in the case where the step passing angle θs is not below the prescribed threshold value Th (step S12: N), the target travel trajectory generating section 38 outputs the target travel trajectory and the target speed profile to the vehicle control section 42, the trajectory generating process ends, and the process proceeds to Figure 6 step S8.

[0120] Referring to Figure 6 In step S8, the vehicle control section 42 controls the host vehicle 1 so that the host vehicle 1 travels in accordance with the target travel trajectory or the speed profile generated in step S7.

[0121] (Modified Example)

[0122] In the above-described example, it is determined whether the step-over angle θs of the target travel trajectory generated by the target travel trajectory generation section 38 is equal to or less than a prescribed threshold Th, and in the case where the step-over angle θs is equal to or less than the prescribed threshold Th, the target travel trajectory is regenerated, but the present application is not limited to this. It is also possible that, in the case where the target travel trajectory generation section 38 generates a target travel trajectory that overcomes the step 24, the target travel trajectory is generated with the step-over angle θs being set to be greater than the prescribed threshold Th by appropriately setting the curvature easing parameter. In this case, it is also possible to omit the step-over angle calculation section 40 and the regeneration determination section 41 shown in FIG. 1. Figure 3

[0123] For example, the target travel trajectory generation section 38 can determine whether to generate a target travel trajectory that overcomes the step 24 based on the driving action plan determined by the driving action plan determination section 36 and the step information acquired by the step determination section 39.

[0124] In the case where the target travel trajectory generation section 38 generates a target travel trajectory that overcomes the step 24, the target travel trajectory can be generated with the step-over angle θs being set to be greater than the prescribed threshold Th by appropriately setting the curvature easing parameter to be smaller than in the case where a target travel trajectory is generated that does not overcome the step 24.

[0125] (EFFECTS OF THE FIRST EMBODIMENT)

[0126] (1) The controller 16 controls the host vehicle 1 so that the host vehicle 1 travels along the target travel trajectory by the controller. The step determination section 39 acquires step information of the step 24 that exists in parallel with the lane 20 along which the host vehicle 1 travels. The target travel trajectory generation section 38 generates a target travel trajectory with the step-over angle θs being greater than the threshold Th in the case where the target travel trajectory is generated that overcomes the step 24.

[0127] Thus, the angle at which the steered wheels of the host vehicle 1 overcome the step 24 becomes small, the interference becomes small, and it is possible to reduce the following error with respect to the target travel trajectory. Thus, it is possible to reduce the possibility of collision with the off-road obstacle.

[0128] (2) The target travel trajectory generation section 38 generates a target travel trajectory based on the detection result of the object around the host vehicle 1. The target travel trajectory generation section 38 regenerates the target travel trajectory with the step-over angle θs being greater than the threshold Th in the case where the step-over angle θs between the generated target travel trajectory and the straight line parallel to the step 24 is equal to or less than the threshold Th.

[0129] Thus, the angle at which the steered wheels of the host vehicle 1 overcome the step 24 becomes small, the interference becomes small, and it is possible to reduce the following error with respect to the target travel trajectory. Thus, it is possible to reduce the possibility of collision with the off-road obstacle.​

[0130] (3) It can be that the higher the step 24, or the larger the inclination of the step 24, the larger the threshold Th is set by the regeneration determination part 41.

[0131] The higher the step, or the larger the inclination angle, the greater the resistance input to the tire from the step 24, the greater the following error with respect to the target travel trajectory, and thus, by increasing the threshold Th, the error can be suppressed.

[0132] (4) It can be that the lower the flat ratio of the tire of the host vehicle 1, or the smaller the outer diameter of the tire, the larger the threshold Th is set by the regeneration determination part 41.

[0133] In terms of the ease with which the steered wheels are affected by the disturbance, the lower the flat ratio of the tire, or the smaller the outer diameter of the tire, the greater the following error with respect to the target travel trajectory, and thus, by increasing the threshold Th, the error can be suppressed.

[0134] (5) It can be that the regeneration determination part 41 acquires obstacle information of obstacles around the host vehicle 1, and in a case where there is an obstacle in the vicinity of the predetermined target travel trajectory on which the host vehicle 1 travels after passing over the step 24, a larger threshold Th is set.

[0135] If there is an obstacle in the position close to the target travel trajectory after passing over the step 24, the error can be suppressed by increasing the threshold Th to avoid collision.

[0136] (6) It can be that the narrower the lane width of the predetermined lane on which the host vehicle 1 travels after passing over the step 24, the larger the threshold Th is set by the regeneration determination part 41.

[0137] If the width of the travel road after passing over the step 24 is narrow, by increasing the threshold Th, the error can be suppressed and deviated to the outside of the travel road, avoiding collision with the obstacle.

[0138] (7) It can be that the target travel trajectory generation part 38 sets the target speed at the time when the host vehicle 1 passes over the step 24 to a slow speed.

[0139] By reducing the vehicle speed, the trajectory correction after passing over the step 24 can be quickly implemented, the state where the error is large is no longer continued, and the following property with respect to the target travel trajectory is improved.

[0140] (8) It can be that the higher the step 24, or the larger the inclination of the step 24, the lower the target speed at the time when the host vehicle 1 passes over the step 24 is set by the target travel trajectory generation part 38.

[0141] The higher the step 24 and the larger the inclination, the larger the amount of departure after passing over the step 24, and therefore, by reducing the vehicle speed, the trajectory correction after passing over the step 24 can be quickly performed, the state of large error is not continued, and the followability to the target travel trajectory is improved.

[0142] (9) It can be that the lower the flat ratio of the tire of the host vehicle 1 or the smaller the outer diameter of the tire, the lower the target speed at the time of passing over the step 24 by the host vehicle 1 is set by the target travel trajectory generation section 38.

[0143] The smaller the flat ratio of the tire or the smaller the outer diameter of the tire, the larger the amount of departure after passing over the step 24, and therefore, by reducing the vehicle speed, the trajectory correction after passing over the step 24 can be quickly performed, the state of large error is not continued, and the followability to the target travel trajectory is improved.

[0144] (10) It can be that the target travel trajectory generation section 38 acquires obstacle information of obstacles around the host vehicle 1, and in a case where there is an obstacle in the vicinity of the predetermined target travel trajectory on which the host vehicle 1 travels after passing over the step 24, the target speed at the time of passing over the step 24 by the host vehicle 1 is set lower.

[0145] If there is an obstacle after passing over the step 24, the risk of collision after passing over is increased, and therefore, by reducing the vehicle speed, the correction after passing over the step 24 can be quickly performed, the state of large error is not continued, and the collision can be avoided.

[0146] (11) It can be that the narrower the lane width of the predetermined lane on which the host vehicle 1 travels after passing over the step 24, the lower the target speed at the time of passing over the step 24 by the host vehicle 1 is set by the target travel trajectory generation section 38.

[0147] The narrower the lane width, the higher the risk of off-road departure after passing over the step 24, and therefore, by reducing the vehicle speed, the correction after passing over the step 24 can be quickly performed, the state of large error is not continued, and the collision can be avoided.

[0148] (12) It can be that the smaller the step passing angle θs, the lower the target speed at the time of passing over the step 24 by the host vehicle 1 is set by the target travel trajectory generation section 38.

[0149] In a case where the step passing angle θs is small, by reducing the vehicle speed, the correction of the path can also be quickly performed, the state of large error is not continued, and the collision can be avoided.

[0150] (13) It can be that the step passing angle calculation section 40 calculates the step passing angle θs formed by a straight line parallel to the step 24 and a trajectory through the center position of the axle of the steered wheel of the host vehicle 1 as the target travel trajectory.

[0151] By considering the locus of the center position of the axle of the steered wheel instead of the center of the vehicle body, the strictness of the tire angle when the steered wheel passes over the step 24 can be improved.

[0152] (Second Embodiment)

[0153] Next, the second embodiment will be described. The extent to which the step passing angle θs can be made close to 90 degrees depends on the travel scenario or the surrounding environment of the host vehicle 1, and the like. That is, the allowable range of the curvature easing parameter that can be adjusted in order to make the step passing angle θs close to 90 degrees depends on the travel scenario or the surrounding environment of the host vehicle 1, and the like. Therefore, there are cases in which the target travel trajectory cannot be generated in such a manner that the step passing angle θs is greater than the threshold value Th.

[0154] Reference Figure 8A Suppose a case in which the target travel trajectory 27 that makes a lane change from the lane 20 over the step 24 to the branch lane 28 is generated. In this case, it is necessary to turn to the opposite side after making the lane change to the branch lane 28, and if the step passing angle θs is made close to 90 degrees, the allowable range of the curvature easing parameter is exceeded, and it is not possible to travel on the inside of the travel road boundary of the branch lane 28 after passing over the step 24. Therefore, the step passing angle θs cannot be made close to 90 degrees.

[0155] Reference Figure 8B In a case in which the lane width W2 of the lane 20 on which the host vehicle 1 travels before passing over the step 24 is narrow, if the step passing angle θs is made close to 90 degrees, the allowable range of the curvature easing parameter is also exceeded, and it is not possible to travel on the inside of the travel road boundary of the lane 20 before passing over the step 24. In this case, the step passing angle θs also cannot be made close to 90 degrees.

[0156] Therefore, the target travel trajectory generation section 38 of the second embodiment determines whether or not it is possible to generate the target travel trajectory in such a manner that the host vehicle 1 travels on the inside of the travel road boundary and the step passing angle θs is greater than the threshold value Th.

[0157] In a case in which it is not possible to generate the target travel trajectory in such a manner that the host vehicle 1 travels on the inside of the travel road boundary and the step passing angle θs is greater than the threshold value Th, the target travel trajectory generation section 38 sets the target vehicle speed at the time at which the host vehicle 1 passes over the step 24 to the prescribed slow travel speed.

[0158] As a result, even in a case in which it is not possible to generate the target travel trajectory in such a manner that the step passing angle θs is greater than the threshold value Th, it is possible to suppress the amount of deviation from the target travel trajectory after passing over the step 24, and to quickly make a correction after passing over the step 24.

[0159] Reference Figure 9 The trajectory generation processing of the second embodiment will be described. The processing of steps S20 to S23 is the same as that described with reference toFigure 7 The processes of the steps S10 to S13 explained above are the same.

[0160] In the step S24, the target travel trajectory generation part 38 determines whether the curvature moderation parameter decreased in the step S23 is within a prescribed allowable range. For example, the target travel trajectory generation part 38 determines whether it is possible to generate the target travel trajectory in which the host vehicle 1 travels inside the travel road boundary, using the curvature moderation parameter decreased in the step S23.

[0161] In the case where the curvature moderation parameter is not within the prescribed allowable range (step S24: N), the process proceeds to the step S26.

[0162] In the step S26, the target travel trajectory generation part 38 sets the target speed curve in such a manner that the target speed at the time when the host vehicle 1 passes the step 24 becomes lower. For example, the target speed curve is set in such a manner that the target speed at the time when the host vehicle 1 passes the step 24 becomes the slow travel speed. After that, the trajectory generation process ends, and the process proceeds to the step S8. Figure 6

[0163] In the case where the curvature moderation parameter is within the prescribed allowable range (step S24: Y), the process proceeds to the step S25. The process of the step S25 is the same as the process of the step S14 explained with reference to FIG. 4. After that, the process returns to the step S22. Figure 7

[0164] (EFFECTS OF THE SECOND EMBODIMENT)

[0165] The object detection part 30 detects the travel road boundary of the lane 20 in which the host vehicle 1 travels. The target travel trajectory generation part 38 sets the target speed of the host vehicle 1 at the time when the host vehicle 1 passes the step 24 to the slow travel speed in the case where it is not possible to generate the target travel trajectory in such a manner that the host vehicle 1 travels inside the travel road boundary and the step overrun angle θs is greater than the threshold value Th.

[0166] Thus, even in the case where it is not possible to generate the target travel trajectory in such a manner that the step overrun angle θs is greater than the threshold value Th, it is possible to suppress the amount of departure from the target travel trajectory after the host vehicle 1 has overrun the step 24, and to quickly perform the correction after the host vehicle 1 has overrun the step 24.

[0167] All of the examples and conditional terms recited herein are intended to be construed in an educational sense to aid the reader in understanding the concepts of the application and the applicants' contributions to the art, and should not be construed as limiting the described examples and conditions to the precise conditions disclosed, and should not be construed as excluding other conditions, examples, and terms that are equivalent in nature to the conditions, examples, and terms described. Embodiments of the application have been described in great detail, but those skilled in the art will understand that these embodiments are merely exemplary of the application as claimed and that many modifications, substitutions and changes can be made by those skilled in the art without departing from the spirit and scope of the present application.

[0168] ​​BRIEF DESCRIPTION OF REFERENCE NUMERALS

[0169] 1 host vehicle

[0170] 2FL, 2FR steered wheels

[0171] 2RL, 2RR wheels

[0172] 3 axle

[0173] 10 drive assist device

[0174] 11 object sensor

[0175] 12 vehicle sensor

[0176] 13 positioning device

[0177] 14 map database

[0178] 15 communication device

[0179] 16 controller

[0180] 17 actuator

[0181] 18 processor

[0182] 19 storage device

[0183] 30 object detection section

[0184] 31 host vehicle position estimation section

[0185] 32 map acquisition section

[0186] 33 detection integration section

[0187] 34 object tracking section

[0188] 35 in-map position calculation section

[0189] 36 drive action plan determination section

[0190] 37 drivable area determination section

[0191] 38 target travel trajectory generation section

[0192] 39 step determination section

[0193] 40 step clearance angle calculation section

[0194] 41 regeneration determination section

[0195] 42 vehicle control section

Claims

1. A drive assist method of controlling a host vehicle by a controller to travel along a target travel trajectory, characterized by, acquiring step information of a step present along a lane in which the host vehicle travels, in a case where it is determined from the step information that the host vehicle passes over the step, generating the target travel trajectory in such a manner that an angle, a step passing angle, which the target travel trajectory makes with a straight line parallel to the step is greater than a threshold value, the threshold value being set to be greater as the step is higher or as the inclination of the step is greater.

2. The drive assist method according to claim 1, characterized by, generating the target travel trajectory based on a detection result of an object around the host vehicle, acquiring step information of a step present along a lane in which the host vehicle travels, in a case where it is determined from the step information that the host vehicle passes over the step, re-generating or correcting the target travel trajectory in such a manner that the step passing angle which the generated target travel trajectory makes with the step is greater than the threshold value when the step passing angle is equal to or less than the threshold value.

3. The drive assist method according to claim 1 or 2, characterized by, the threshold value being set to be greater as a flat rate of a tire of the host vehicle is lower or as an outer diameter of the tire is smaller.

4. The drive assist method according to claim 1 or 2, characterized by, acquiring obstacle information of an obstacle around the host vehicle, the threshold value being set to be greater in a case where an obstacle is present in a vicinity of the predetermined target travel trajectory along which the host vehicle travels after passing over the step.

5. The drive assist method according to claim 1 or 2, characterized by, a target speed at a time when the host vehicle passes over the step being set to be a slow speed.

6. The drive assist method according to claim 1 or 2, characterized by, the target speed at the time when the host vehicle passes over the step being set to be lower as the step is higher or as the inclination of the step is greater.

7. The drive assist method according to claim 1 or 2, characterized by, the target speed at the time when the host vehicle passes over the step being set to be lower as a flat rate of a tire of the host vehicle is lower or as an outer diameter of the tire is smaller.

8. The drive assist method according to claim 1 or 2, characterized by, acquiring obstacle information of an obstacle around the host vehicle, the target speed at the time when the host vehicle passes over the step being set to be lower in a case where an obstacle is present in a vicinity of the predetermined target travel trajectory along which the host vehicle travels after passing over the step.

9. The drive assist method according to claim 1 or 2, characterized by, the target speed at the time when the host vehicle passes over the step being set to be lower as a lane width of a predetermined lane along which the host vehicle travels after passing over the step is narrower.

10. The drive assist method according to claim 1 or 2, characterized by, detecting a travel road boundary of a lane in which the host vehicle travels, In a case where the target travel trajectory is generated in a manner that the host vehicle cannot travel inside the travel road boundary and the step-over angle is greater than the threshold value, a target vehicle speed at a time when the host vehicle passes over the step is set to a slow travel speed.

11. The drive assist method according to claim 1 or 2, characterized in that, The smaller the step-over angle, the lower the target vehicle speed at the time when the host vehicle passes over the step is set.

12. The drive assist method according to claim 1 or 2, characterized in that, The step-over angle is calculated using a trajectory through a center position of an axle of a steered wheel of the host vehicle as the target travel trajectory.

13. A driving assistance device that controls a vehicle so that the vehicle travels along a target driving trajectory, characterized in that: provided with: a sensor that detects an object around the host vehicle; a controller that acquires step information of a step present along a lane in which the host vehicle travels, generates the target travel trajectory in a manner that a step-over angle, which is an angle formed by a straight line parallel to the step and the target travel trajectory, is greater than a threshold value in a case where it is determined from the step information that the host vehicle passes over the step, The higher the step, or the greater the inclination of the step, the greater the threshold value is set.

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