JP7393721B2 - Driving route generation system and vehicle driving support system - Google Patents

Description

The present invention relates to a driving route generation system that generates a driving route for a vehicle, and a vehicle driving support system that supports driving of a vehicle based on the driving route.

Conventionally, a driving route for the own vehicle is set based on the surrounding conditions of the own vehicle and the state of the own vehicle, and based on this driving route, vehicle driving support (specifically, driving assist control and automatic Technology has been developed to perform (operation control). For example, in Patent Document 1, when changing lanes, a starting point and an ending point for changing lanes are set based on information about the own vehicle and information about other vehicles around the own vehicle, and a driving route is determined according to these points. A technique for generating this is disclosed.

JP 2017-100657 Publication

By the way, the inventors of the present application have proposed that when the own vehicle changes lanes, if there is a following vehicle near the own vehicle on the lane to which the own vehicle is changing, the following vehicle (basically Generally speaking, it is the driver of the following vehicle, but if the following vehicle is driving automatically using a vehicle driving support system, it is the system (hereinafter the same shall apply). I thought it would be good if I could generate it. In this way, it is possible to make the following vehicle recognize the necessity of deceleration, and it is possible to ensure safety when changing lanes. That is, the timing of deceleration of the following vehicle can be accelerated, and it is possible to prevent a collision between the own vehicle and the following vehicle (especially a rear-end collision with the following vehicle) when changing lanes.

Note that the above-mentioned Patent Document 1 only describes the generation of a driving route when changing lanes, but does not disclose any of the problems that the inventor of the present application focused on, and naturally, There is no disclosure or suggestion of any technology that can solve this problem.

The present invention has been made in order to solve the above-mentioned problems, and when a vehicle changes lanes, it appropriately informs following vehicles in the lane to which the vehicle is changing lanes that the vehicle intends to change lanes. An object of the present invention is to provide a driving route generation system that can generate a driving route that can be recognized by a person, and a vehicle driving support system that can provide driving support for a vehicle based on this driving route.

In order to achieve the above object, the present invention is a driving route generation system, and includes a driving path information acquisition device that acquires driving path information regarding a driving path of a vehicle, and an obstacle information acquisition device regarding obstacles on the driving path. and an arithmetic device configured to generate a driving route for the vehicle to travel on the driving path based on the driving path information and the obstacle information. When changing lanes, the system determines whether there is a following vehicle near the vehicle on the lane to which it is changing based on the driving path information and obstacle information, and if it is determined that there is a following vehicle, The calculation device is configured to generate a driving route such that the yaw angular velocity generated when the vehicle performs a lane change operation is greater than that when it is determined that there is no following vehicle, and the calculation device If it is determined that there is a following vehicle, a driving route is generated such that the yaw angular velocity that occurs when the vehicle starts a lane change operation is greater than when it is determined that there is no following vehicle. The arithmetic unit is configured to calculate x, which is a line connecting a starting point according to the current position of the vehicle and an end point determined in front of the vehicle, and which is defined in each of the direction in which the traveling path extends and the width direction of the traveling path. A driving route is generated based on a line expressed by an n-dimensional function using coordinates and y-coordinates, and if it is determined that there is no following vehicle, the yaw angular velocity at least at the starting point is set to zero. A driving route is generated by applying one constraint condition to an n-dimensional function, and a second constraint condition is set in which the yaw angular velocity at least at the starting point is set to non-zero when it is determined that a following vehicle exists. It is configured to generate a travel route by applying it to an n-dimensional function, and the n-dimensional function is characterized in that it is one of a cubic function, a quartic function, and a quintic function .

In the present invention configured as described above, when the vehicle changes lanes, if it is determined that there is a following vehicle near the vehicle on the lane to which the vehicle is changing, the arithmetic device determines that this following vehicle does not exist. A travel route (target travel route) is generated in which the yaw angular velocity generated when the vehicle performs a lane change operation is greater than that in the determined case. This makes it easier for the following vehicle to notice the lane change, or in other words, increases the visual conspicuousness of the lane change operation to the following vehicle, allowing the following vehicle to appropriately recognize the lane change intention. Therefore, according to the present invention, it is possible to make the following vehicle recognize the necessity of deceleration, and it is possible to ensure safety when changing lanes. That is, the timing of deceleration of the following vehicle can be made earlier, and it is possible to prevent a collision with the following vehicle (especially a rear-end collision with the following vehicle) when changing lanes.
In addition, the above-mentioned "yaw angular velocity that occurs when a vehicle performs a lane change operation" refers to the rate of change (degree of change) of the vehicle's direction, yaw rate, and yaw angle that occur when changing lanes. Corresponds to the rate of change.
Further, according to the present invention, since a driving route is generated such that the yaw angular velocity that occurs at the start of the lane change operation becomes large, it is possible to further increase the visual conspicuousness of the lane change operation to the following vehicle, The intention can be effectively recognized by the following vehicle. Further, according to the present invention, when it is determined that there is a following vehicle near the vehicle, a driving route is generated by applying the second constraint condition of setting the yaw angular velocity at the starting point to non-zero to the n-dimensional function. Therefore, it is possible to appropriately generate a travel route that increases the yaw angular velocity that occurs when changing lanes.

In the present invention, preferably, the arithmetic device uses at least a condition that the yaw angular velocity at the starting point is set to zero and the yaw angular velocity at the end point is set to zero as the first constraint condition, and the second constraint is set to zero. The constraint condition is configured to use at least the following conditions: yaw angular velocity at the start point is set to non-zero, yaw angular velocity at the end point is set to zero, and yaw angular acceleration at the end point is set to zero. .
According to the present invention configured in this way, when the first constraint condition is used, it is possible to appropriately reduce the yaw angular velocity that occurs in the vehicle at the start and end of a lane change. On the other hand, when the second constraint condition is used, the yaw angular velocity generated in the vehicle at the beginning of the lane change can be appropriately made relatively large, while the yaw angular velocity generated in the vehicle at the end of the lane change can be made relatively large. The angular velocity and yaw angular acceleration can be reduced, that is, the lane change operation can be gradually converged.

In the present invention, preferably, the calculation device calculates the headway time between the vehicle and the following vehicle based on the speed of the vehicle and the inter-vehicle distance between the vehicle and the following vehicle included in the obstacle information, and determines the headway time between the vehicle and the following vehicle. time, it is determined that there is a following vehicle near the vehicle on the destination lane , or the speed of the vehicle, the speed of the following vehicle included in the obstacle information, and the distance between the vehicle and the following vehicle are determined. Based on the distance, the collision margin time between the vehicle and the following vehicle is calculated, and if the collision margin time is less than a predetermined time, it is determined that there is a trailing vehicle near the vehicle on the lane to which the vehicle is changing, or The vehicle headway time and collision margin time are calculated, and if the vehicle headway time is less than a predetermined time and the collision margin time is less than a predetermined time, it is determined that a following vehicle exists near the vehicle on the lane to which the vehicle is changing. ing.
According to the present invention configured in this way, it is determined whether or not there is a following vehicle near the vehicle on the lane to which the vehicle is changing based on the headway time and collision margin time, so that the intention to change lanes should be recognized. The presence or absence of a following vehicle can be accurately determined.

In another aspect, in the present invention, the vehicle driving support system includes a control device configured to control the driving of the vehicle so that the vehicle travels along the travel route generated by the above-described travel route generation system. It is characterized by
According to the present invention configured in this way, by controlling the driving of the vehicle based on the travel route generated by the travel route generation system, when the vehicle changes lanes, it is possible to notify the destination of the lane change that the vehicle intends to change lanes. It is possible to appropriately recognize a following vehicle existing on the lane.

According to the driving route generation system of the present invention, when a vehicle changes lanes, a driving route is created that allows a following vehicle in the lane to which the vehicle is changing to appropriately recognize that the vehicle intends to change lanes. Moreover, according to the vehicle driving support system of the present invention, it is possible to appropriately perform vehicle driving support based on such a driving route.

1 is a block diagram showing a schematic configuration of a vehicle driving support system to which a driving route generation system according to an embodiment of the present invention is applied. FIG. 2 is an explanatory diagram of the basic concept of driving route generation according to an embodiment of the present invention. FIG. 3 is an explanatory diagram of calculations for setting driving route candidates according to the embodiment of the present invention. FIG. 3 is an explanatory diagram of a driving route candidate according to an embodiment of the present invention. 3 is a flowchart illustrating travel route generation and driving support according to an embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A driving route generation system and a vehicle driving support system according to embodiments of the present invention will be described below with reference to the accompanying drawings.

[System configuration]
First, with reference to FIG. 1, the configuration of a vehicle driving support system to which a driving route generation system according to an embodiment of the present invention is applied will be described. FIG. 1 is a block diagram showing a schematic configuration of a vehicle driving support system to which a driving route generation system according to an embodiment of the present invention is applied.

The vehicle driving support system 100 has a function as a driving route generation system that sets a driving route for the vehicle 1 to travel on a driving road (hereinafter referred to as a "target driving route" as appropriate), and also has the function of a driving route generation system that sets the driving route for the vehicle 1 to travel on a driving road. The vehicle is configured to perform driving support control (driving assist control or automatic driving control) so that the vehicle travels along a target travel route. As shown in FIG. 1, the vehicle driving support system 100 includes an ECU (Electronic Control Unit) 10 as a calculation device and a control device, a plurality of sensors, and a plurality of control systems.

Specifically, the plurality of sensors include a camera 21, a radar 22, a vehicle speed sensor 23 for detecting the behavior of the vehicle 1 and driving operations by the occupant, an acceleration sensor 24, a yaw rate sensor 25, a steering angle sensor 26, An accelerator sensor 27 and a brake sensor 28 are included. Furthermore, the plurality of sensors include a positioning system 29 and a navigation system 30 for detecting the position of the vehicle 1. The plurality of control systems include an engine control system 31, a brake control system 32, and a steering control system 33.

In addition, other sensors include a surrounding sonar that measures the distance and position of surrounding structures with respect to the vehicle 1, a corner radar that measures the approach of surrounding structures at four corners of the vehicle 1, and a It may also include an inner camera to take pictures.

The ECU 10 executes various calculations based on signals received from a plurality of sensors, and controls the engine system, brake system, and steering system appropriately for the engine control system 31, brake control system 32, and steering control system 33, respectively. Sends a control signal to operate the device. The ECU 10 is composed of a computer including one or more processors (typically a CPU), a memory (ROM, RAM, etc.) that stores various programs, an input/output device, and the like. Note that the ECU 10 corresponds to an example of a "computation device" and a "control device" in the present invention.

The camera 21 photographs the surroundings of the vehicle 1 and outputs image data. Based on the image data received from the camera 21, the ECU 10 detects objects (for example, a preceding vehicle (vehicle in front), a following vehicle (vehicle in the rear), a parked vehicle, a pedestrian, a driving path, a marking line (lane boundary line, a white line), etc. , yellow lines), traffic signals, traffic signs, stop lines, intersections, obstacles, etc.). Note that the ECU 10 may acquire information about the object from outside through traffic infrastructure, inter-vehicle communication, or the like. As a result, the type, relative position, moving direction, etc. of the object are specified.

The radar 22 measures the position and speed of objects (particularly, preceding vehicles, following vehicles, parked vehicles, pedestrians, fallen objects on the road, etc.). As the radar 22, for example, a millimeter wave radar can be used. The radar 22 transmits radio waves in the traveling direction of the vehicle 1, and receives reflected waves generated when the transmitted waves are reflected by objects. Then, the radar 22 measures the distance between the vehicle 1 and the object (for example, the inter-vehicle distance) and the relative speed of the object with respect to the vehicle 1 based on the transmitted wave and the received wave. In this embodiment, instead of the radar 22, a laser radar, an ultrasonic sensor, or the like may be used to measure the distance and relative speed to the object. Further, the position and velocity measuring device may be configured using a plurality of sensors.

Note that the camera 21 and the radar 22 correspond to an example of a "driving path information acquisition device" and an "obstacle information acquisition device" in the present invention.

Vehicle speed sensor 23 detects the absolute speed of vehicle 1. Acceleration sensor 24 detects the acceleration of vehicle 1. This acceleration includes acceleration in the longitudinal direction and acceleration in the lateral direction (that is, lateral acceleration). Note that the acceleration includes not only the rate of change in speed in the direction in which the speed increases, but also the rate of change in speed in the direction in which the speed decreases (that is, deceleration).

The yaw rate sensor 25 detects the yaw rate (hereinafter referred to as "yaw angular velocity" as appropriate) of the vehicle 1. The steering angle sensor 26 detects the rotation angle (steering angle) of the steering wheel of the vehicle 1. The ECU 10 executes a predetermined calculation based on the absolute speed detected by the vehicle speed sensor 23 and the steering angle detected by the steering angle sensor 26, thereby determining the yaw angle of the vehicle 1 (that is, with respect to the The angle formed by the longitudinal direction of the vehicle 1 can be acquired. The accelerator sensor 27 detects the amount of depression of the accelerator pedal. Brake sensor 28 detects the amount of depression of the brake pedal.

The positioning system 29 is a GPS system and/or a gyro system, and detects the position of the vehicle 1 (current vehicle position information). The navigation system 30 internally stores map information and can provide the ECU 10 with the map information. The ECU 10 identifies roads, intersections, traffic signals, buildings, etc. existing around the vehicle 1 (particularly in the direction of travel) based on map information and current vehicle position information. The map information may be stored within the ECU 10. Note that the navigation system 30 also corresponds to an example of a "driving route information acquisition device" in the present invention.

Engine control system 31 controls the engine of vehicle 1 . The engine control system 31 is a component that can adjust the engine output (driving force), such as a spark plug, a fuel injection valve, a throttle valve, a variable valve mechanism that changes the opening and closing timing of intake and exhaust valves, etc. including. ECU 10 transmits a control signal to engine control system 31 to change engine output when it is necessary to accelerate or decelerate vehicle 1.

The brake control system 32 controls the brake device of the vehicle 1. The brake control system 32 is a component that can adjust the braking force of the brake device, and includes, for example, a hydraulic pump and a valve unit. When it is necessary to decelerate the vehicle 1, the ECU 10 transmits a control signal to the brake control system 32 to generate a braking force.

Steering control system 33 controls the steering device of vehicle 1 . The steering control system 33 is a component that can adjust the steering angle of the vehicle 1, and includes, for example, an electric motor of an electric power steering system. When the traveling direction of the vehicle 1 needs to be changed, the ECU 10 transmits a control signal to the steering control system 33 to change the steering direction.

[Driving route generation]
Next, driving route generation executed by the ECU 10 described above in the embodiment of the present invention will be described. First, with reference to FIG. 2, the basic concept of travel route generation according to the embodiment of the present invention will be explained. FIG. 2 shows the vehicle 1 traveling on the road 5. As shown in FIG.

First, the ECU 10 performs calculations for specifying a position on the driving path 5 based on the driving path information. The traveling route information is information regarding the traveling route 5 on which the vehicle 1 is traveling, and is acquired by the camera 21, the radar 22, the navigation system 30, and the like. The driving path information includes, for example, information regarding the shape of the driving path (straight line, curve, curve curvature), driving path width, number of lanes, lane width, and the like.

Next, the ECU 10 sets a plurality of virtual grid points G _n (n=1, 2, . . . N) on the running road 5 that exists in front of the vehicle 1 in the traveling direction by calculation based on the running road information. do. When the direction in which the running path 5 extends is defined as the x direction, and the width direction of the running path 5 is defined as the y direction, the grid points G _n are arranged in a grid pattern along the x direction and the y direction. Note that the origin of the xy coordinates is set to a point corresponding to the position of the vehicle 1.

The range in which the ECU 10 sets the grid points G _n extends along the travel path 5 by a distance L in front of the vehicle 1 . The distance L is calculated based on the speed of the vehicle 1 at the time of execution of the calculation. In this embodiment, the distance L is the distance expected to be traveled in a predetermined fixed time t (for example, 3 seconds) at the speed (V) at the time of execution of the calculation (L=V×t). However, the distance L may be a predetermined fixed distance (eg 100 m) or may be a function of velocity (and acceleration). Further, the width W of the range in which the grid points G _n are set is set to a value substantially equal to the width of the travel path 5 . By setting a plurality of grid points G _n in this manner, it becomes possible to specify a position on the travel path 5.

Note that, since the travel path 5 shown in FIG. 2 is a straight section, the grid points G _n are arranged in a rectangular shape. However, since the grid points G _n are arranged along the direction in which the running road extends, if the running road includes a curved section, the grid points G _n are arranged along the curvature of the curved section.

Next, the ECU 10 executes calculations for setting a driving route candidate RC (that is, a candidate that can become the target driving route on which the vehicle 1 is actually driven) based on the driving path information and the obstacle information. Obstacle information includes information such as the presence or absence of an obstacle on the travel path 5 of the vehicle 1 (for example, objects that may become an obstacle to the vehicle 1, such as a preceding vehicle, a following vehicle, a parked vehicle, or a pedestrian), and the moving direction of the obstacle. , information regarding the moving speed of obstacles, etc., and is acquired by the camera 21 and the radar 22.

Specifically, the ECU 10 sets a plurality of driving route candidates RC by route searching using the state lattice method. According to the state lattice method, a plurality of travel route candidates RC are set so as to branch from the position of the vehicle 1 toward grid points G _n existing in the direction of travel of the vehicle 1 . FIG. 2 shows driving route candidates RC _a , RC _b , and RC _c that are part of a plurality of driving route candidates RC set by the ECU 10 .

Next, as shown in FIG. 2, the ECU 10 sets a plurality of sampling points SP along each driving route candidate RC, and calculates the route cost at each sampling point SP. This sampling point SP is a discrete point (position) on the route of each driving route candidate RC, at which the route cost is calculated. Specifically, the ECU 10 calculates the route cost of each of the plurality of sampling points SP for each of the plurality of driving route candidates RC.

Next, the ECU 10 selects one route with the minimum route cost from among the plurality of driving route candidates RC based on the route cost of each of the plurality of driving route candidates RC calculated in this way, and selects this route. Set as the target driving route. Then, the ECU 10 transmits a control signal to at least one of the engine control system 31, the brake control system 32, and the steering control system 33 so that the vehicle 1 travels along the set target travel route.

Next, with reference to FIG. 3, calculations for setting a driving route candidate RC in the embodiment of the present invention will be specifically described. As shown in FIG. 3, the driving route candidate RC extends from the starting point P _s to the ending point P _e . The starting point P _s is the position of the vehicle 1 at the time of execution of the calculation, typically the current position of the vehicle 1. The coordinates of the starting point P _s are expressed as (x _s , y _s ). In the example shown in FIG. 3, the vehicle 1 is located at the origin of the xy coordinates, so the coordinates of the starting point _Ps are (0, 0). The end point P _e is one grid point G _n (a predetermined grid point located forward in the direction of travel of the vehicle 1) selected from a plurality of grid points G _n , and its coordinates are (x _e , y _e ). expressed.

The ECU 10 provisionally defines a quintic function in which the y-coordinate and the x-coordinate are variables, as shown by equation f1, as a curve to be set as the driving route candidate RC. Note that formula f1 is an example of an "n-order function" according to the present invention, but it is not limited to using a quintic function as the n-order function, and various other functions (for example, a cubic function or a quartic function) can be used. functions, etc.) may also be used. Further, a curve drawn on the xy coordinates based on the formula f1 is an example of a "line" according to the present invention.

a to f are unknown coefficients. In order to specifically define the curve extending from the starting point P _s to the ending point P _e , it is necessary to solve at least six relational expressions and determine the coefficients a to f. Therefore, the ECU 10 prepares equations f2 to f4, which are obtained by differentiating equation f1 with respect to x once to three times.

The coordinates (x _s , y _s ) of the starting point P _s and the coordinates (x _e , y _e ) of the ending point P _e each satisfy the relationship of formula f1. Therefore, the ECU 10 can obtain the relational expressions f5 and f6.

Furthermore, in the following description, as shown in FIG. 3, the angle that the straight line 1L extending along the longitudinal direction of the vehicle 1 makes with the x-axis will be referred to as the "yaw angle." Furthermore, the yaw angle at the starting point P _s is assumed to be “H _s ”, and the yaw angle at the ending point P _e is assumed to be “H _e ”. The units of the yaw angles H _s and _He are both radians.

The tangent of the x _- coordinate ( _xs ) of the starting point _Ps and the yaw angle _Hs at the starting point Ps satisfies the relationship of equation f2. Furthermore, the tangent of the x coordinate (x _e ) of the end point P _e and the yaw angle H _e at the end point P _e also satisfies the relationship of equation f2. Therefore, the ECU 10 can obtain relational expressions f7 and f8.

Since equation f3 indicates the rate of change of y' with respect to x, it has a correlation with the yaw angular velocity. From this, the x-coordinate ( _xs ) of the starting point _Ps and the yaw angular velocity _Ks at the starting point _Ps approximately satisfy the relationship of equation f3. Further, the x-coordinate (x _e ) of the end point P _e and the yaw angular velocity K _e at the end point P _e also approximately satisfy the relationship of equation f3. Therefore, the ECU 10 can obtain the relational expressions f9 and f10.

Further, since the equation f4 indicates the rate of change of y'' with respect to x, it has a correlation with the yaw angular acceleration. From this, the x-coordinate ( _xs ) of the starting point _Ps and the yaw angular acceleration _Ks ' at the starting point _Ps approximately satisfy the relationship of formula f4. Furthermore, the x-coordinate (x _e ) of the end point P _e and the yaw angular acceleration K _e ' also roughly satisfy the relationship of equation f4. Therefore, the ECU 10 can obtain the relational expressions f11 and f12.

The ECU 10 appropriately sets a plurality of constraint conditions (boundary conditions) indicating the state of the vehicle 1 (that is, coordinates, yaw angle, yaw angular velocity, and yaw angular acceleration) at each of _the starting point P _s and the ending point P e. The ECU 10 determines the coefficients a to f by applying the constraint and solving at least six of the eight relational expressions f5 to f12. Thereby, the ECU 10 can specifically define a curve that extends from the starting point P _s to the ending point P _e and is set as the driving route candidate RC.

Next, with reference to FIG. 4, the travel route candidate RC according to the embodiment of the present invention will be specifically described. FIG. 4 illustrates two driving route candidates RC1 and RC2 that are set when the vehicle (hereinafter referred to as "self-vehicle") 1 changes lanes.

In the present embodiment, when the own vehicle 1 changes lanes, if there is a following vehicle 3 near the own vehicle 1 on the lane to which the own vehicle 1 is changing, the ECU 10 compares the case where the following vehicle 3 does not exist. Therefore, the yaw angular velocity that occurs when the host vehicle 1 performs a lane change operation, specifically, the yaw angular velocity that occurs when the host vehicle 1 starts a lane change operation increases. A route candidate RC is set, and a target travel route is generated according to the route candidate RC. Specifically, as shown in FIG. 4, when there is a following vehicle 3 near the host vehicle 1 on the lane to which the vehicle is changing, the ECU 10 controls the driving so that the yaw angular velocity that occurs at the start of the lane change becomes large. A route candidate RC2 (broken line) is set. On the other hand, if there is no following vehicle 3 near the own vehicle 1 on the lane to which the vehicle is changing, the ECU 10 sets a driving route candidate RC1 (solid line) that reduces the yaw angular velocity that occurs at the start of the lane change. . Note that these driving route candidates RC1 and RC2 may be treated not as candidates but as target driving routes to be finally applied.

According to this embodiment, by applying the driving route candidate RC2 when changing lanes, compared to the case where the driving route candidate RC1 is applied, the starting of the lane change by the host vehicle 1 is delayed by the following vehicle 3 (basically The driver of the following vehicle 3 is the driver of the following vehicle 3, but if the following vehicle 3 is driving automatically by a vehicle driving support system, it is the system. The visual conspicuousness of the following vehicle 3 with respect to the movement increases (see the dashed line area A1 in FIG. 4). This allows the following vehicle 3 to appropriately recognize the necessity of deceleration, and it becomes possible to ensure safety when changing lanes. That is, the timing of deceleration of the following vehicle 3 can be made earlier, and it becomes possible to prevent a collision between the own vehicle 1 and the following vehicle 3 (particularly a rear-end collision with the following vehicle 3) when changing lanes.

Here, the first and second constraint conditions used in respectively setting the above-mentioned driving route candidates RC1 and RC2, specifically, the coefficients that define the formula f1 of the quintic function applied to each of the driving route candidates RC1 and RC2. The first and second constraint conditions used to determine a to f will be explained.

In the present embodiment, the first constraint condition applied to set the driving route candidate RC1, that is, the first constraint condition applied when there is no following vehicle 3 near the own vehicle 1 on the lane to change to, is as follows. Use the conditional expression.

That is, the first constraint condition uses at least the condition that the yaw angular velocity K _s at the starting point P _s is set to zero, and the yaw angular velocity K _e at the end point P _e is set to zero. By doing so, the yaw angular velocity generated in the own vehicle 1 at the start and end of the lane change is reduced.

By substituting the conditional expression of the first constraint condition into the above expressions f1, f2, and f3, the following expressions are obtained.

Then, the coefficients a to f are determined as follows from the equation obtained by replacing the above equation with a matrix.

The ECU 10 sets a driving route candidate RC1 based on a quintic function formula obtained by substituting the thus determined coefficients a to f into the formula f1. Note that the first constraint condition may further include a condition in which the yaw angle H _s at the starting point P _s and/or the yaw angle _He at the end point P _e are set to zero.

On the other hand, in the present embodiment, the second constraint condition applied to set the driving route candidate RC2, that is, the second constraint condition applied when the following vehicle 3 exists near the own vehicle 1 on the lane to change to. , using the following conditional expression.

That is, in the second constraint condition, at least the yaw angular velocity K _s at the start point P _s is set to non-zero, the yaw angular velocity K _e at the end point P _e is set to zero, and the yaw angular acceleration at the end point P _e The condition that K _e ' is set to zero is used. By doing this, the yaw angular velocity and yaw angular acceleration generated in the host vehicle 1 at the end of the lane change are reduced while allowing the yaw angular velocity generated in the host vehicle 1 to increase to some extent at the start of the lane change. In other words, the lane change operation is made to gradually converge.

By substituting the conditional expressions of the second constraint condition into the above expressions f1, f2, f3, and f4, the following expressions are obtained.

Then, the coefficients a to f are determined as follows from the equation obtained by replacing the above equation with a matrix.

The ECU 10 sets a driving route candidate RC2 based on a quintic function formula obtained by substituting the thus determined coefficients a to f into the formula f1. Note that the second constraint condition may further include a condition in which the yaw angle H _s at the starting point P _s and/or the yaw angle _He at the ending point P _e are set to zero.

[Processing flow]
Next, with reference to FIG. 5, the flow of processing performed in the embodiment of the present invention will be described. FIG. 5 is a flowchart showing driving route generation and driving support according to an embodiment of the present invention. The process according to this flowchart is repeatedly executed by the ECU 10 at a predetermined period (for example, every 0.05 to 0.2 seconds).

First, in step S1, the ECU 10 acquires various types of information from the plurality of sensors shown in FIG. 1 (particularly the camera 21, radar 22, vehicle speed sensor 23, navigation system 30, etc.). In this case, the ECU 10 acquires at least the above-described traveling route information and obstacle information.

Next, in step S2, the ECU 10 specifies the shape of the travel path 5 (for example, the direction in which the travel path 5 extends, the width of the travel path 5, etc.) based on the travel path information, and also identifies a plurality of shapes on the travel path 5. Set grid points G _n (n=1, 2, . . . N). For example, the ECU 10 sets grid points G _n every 10 m in the x direction and every 0.875 m in the y direction.

Next, in step S3, the ECU 10 determines whether there is a lane change request for the vehicle 1. For example, the ECU 10 controls the vehicle 1 when the driver of the vehicle 1 performs a turn signal operation to change lanes, or when the currently set target travel route includes a route for changing lanes. It is determined that there is a lane change request.

As a result of step S3, if the ECU 10 does not determine that there is a lane change request from the vehicle 1 (step S3: No), the process proceeds to step S7. In this case, the ECU 10 sets a plurality of driving route candidates RC using a normal method without considering lane changes (step S7). Basically, the ECU 10 sets a plurality of travel route candidates RC by route search using the state lattice method based on travel route information and obstacle information. Specifically, the ECU 10 sets a plurality of driving route candidates RC so as to branch from the position of the vehicle 1 toward grid points G _n existing in the traveling direction.

On the other hand, if the ECU 10 determines that there is a lane change request from the vehicle 1 (step S3: Yes), the process proceeds to step S4. In step S4, the ECU 10 determines whether or not there is no following vehicle 3 near the vehicle 1 on the lane to which the vehicle is changing. In making this determination, the ECU 10 first detects the following vehicle 3 existing behind (or to the side of) the vehicle 1 on the lane to which the vehicle is changing based on the obstacle information. If there are a plurality of following vehicles 3 on the lane to which the vehicle is changing, the ECU 10 may detect the following vehicle 3 that is closest to the vehicle 1 .

The ECU 10 then uses the speed of the vehicle 1 detected by the vehicle speed sensor 23, the detected speed of the following vehicle 3, and the distance between the following vehicle 3 and the vehicle 1 (these are also included in the obstacle information). Based on this, the time-head way (THW) and time to collision (TTC) of the vehicle 1 and the following vehicle 3 are calculated. The ECU 10 calculates headway time by dividing the inter-vehicle distance between the vehicle 1 and the following vehicle 3 by the speed of the vehicle 1, and calculates the inter-vehicle distance between the vehicle 1 and the following vehicle 3 by calculating the relative speed between the vehicle 1 and the following vehicle 3. The collision margin time is calculated by dividing by (|speed of vehicle 1 - speed of following vehicle 3 |).

Then, if the headway time is equal to or greater than the predetermined time and the collision margin time is equal to or greater than the predetermined time, the ECU 10 determines that there is no following vehicle 3 near the vehicle 1 on the lane to which the vehicle is changing (step S4: Yes), proceed to step S5. Note that even if no following vehicle 3 is detected on the destination lane in the first place, the ECU 10 determines that there is no following vehicle 3 near the vehicle 1 on the destination lane (step S4: Yes). ), proceed to step S5. In step S5, the ECU 10 decides to apply the above-described first constraint condition, and then proceeds to step S7, and based on the formula f1 of the quintic function determined by applying the first constraint condition, the ECU 10 starts driving. Set route candidate RC.

On the other hand, if the headway time is less than the predetermined time or if the collision margin time is less than the predetermined time, the ECU 10 determines that the following vehicle 3 is present near the vehicle 1 on the lane to which the vehicle is changing (step S4 :No), proceed to step S6. In step S6, the ECU 10 decides to apply the above-described second constraint condition, and then proceeds to step S7, where the ECU 10 determines whether the vehicle is traveling based on the formula f1 of the quintic function determined by applying the second constraint condition. Set route candidate RC.

Note that in the above example, it was determined that the following vehicle 3 was present near the vehicle 1 if the headway time was less than a predetermined time or if the collision margin time was less than a predetermined time, but in other examples It may be determined that the following vehicle 3 is present near the vehicle 1 when the headway time is less than a predetermined time and the collision margin time is less than a predetermined time (that is, when both conditions are satisfied). In addition, in the above example, both the headway time and the collision margin time are used to determine whether or not the following vehicle 3 exists near the vehicle 1, but in other examples, the headway time and the collision margin time are used. The determination may be made using only one of them.

Next, after step S7 described above, in step S8, the ECU 10 sets a plurality of sampling points SP along each driving route candidate RC. For example, the ECU 10 sets sampling points SP at equal intervals (in one example, every 0.2 m) in the x direction on each of the driving route candidates RC.

Next, in step S9, the ECU 10 calculates the route cost of each of the plurality of travel route candidates RC. Specifically, the ECU 10 calculates the route cost of each of the plurality of sampling points SP for each of the plurality of driving route candidates RC. Then, the ECU 10 calculates a route cost to be applied to one traveling route candidate RC from a plurality of route costs calculated for a plurality of sampling points SP in one traveling route candidate RC. For example, the ECU 10 sets the average value of a plurality of route costs at a plurality of sampling points SP as the route cost of one driving route candidate RC. In this way, the ECU 10 calculates route costs for all of the plurality of travel route candidates RC.

Next, in step S10, the ECU 10 sets a target travel route. Specifically, the ECU 10 selects one route with the minimum route cost from among the plurality of driving route candidates RC based on the route cost of each of the plurality of driving route candidates RC calculated as described above. , this route is set as the target travel route.

Next, in step S11, the ECU 10 performs driving control (vehicle behavior control) including speed control and/or steering control of the vehicle 1 so that the vehicle 1 travels along the target travel route. Specifically, the ECU 10 transmits a control signal to at least one of the engine control system 31, brake control system 32, and steering control system 33, and executes at least one of engine control, braking control, and steering control. do.

[Action and effect]
Next, the functions and effects of the embodiments of the present invention will be explained.

In this embodiment, when the vehicle 1 changes lanes, if it is determined that the following vehicle 3 exists near the vehicle 1 on the lane to which the vehicle 1 is changing, the ECU 10 determines that the following vehicle 3 does not exist. A target travel route is generated such that the yaw angular velocity generated when the vehicle 1 starts an operation for changing lanes is larger than that in the case where the vehicle 1 starts an operation for changing lanes. This makes it easier for the following vehicle 3 to notice the lane change initiation by the vehicle 1. In other words, the visual conspicuousness of the lane change initiation action by the vehicle 1 to the following vehicle 3 increases, and the vehicle 1 becomes aware of the intention to change lanes. The following vehicle 3 can be appropriately recognized. Therefore, according to this embodiment, it is possible to make the following vehicle 3 appropriately recognize the necessity of deceleration, and it is possible to ensure safety when changing lanes. That is, the timing of deceleration of the following vehicle 3 can be made earlier, and it becomes possible to prevent a collision between the vehicle 1 and the following vehicle 3 (particularly a rear-end collision with the following vehicle 3) when changing lanes.

Further, according to the present embodiment, the ECU 10 executes the target travel based on a line expressed by a quintic function that connects the starting point P _s corresponding to the current position of the vehicle 1 and the ending point P _e determined in front of the vehicle 1. When a route is generated and it is determined that the following vehicle 3 does not exist near the vehicle 1 on the lane to change to, the first constraint condition is to set at least the yaw angular velocity K _s at the starting point P _s to zero. A second constraint is applied to a quintic function to generate a target travel route, and when it is determined that the following vehicle 3 exists, the yaw angular velocity K _s at least at the starting point P _s is set to non-zero. A target travel route is generated by applying the conditions to a quintic function. As a result, when it is determined that the following vehicle 3 exists near the vehicle 1, a target driving route is created in which the yaw angular velocity that occurs when changing lanes is greater than when it is determined that the following vehicle 3 does not exist. can be generated appropriately.

Further, according to the present embodiment, the ECU 10 sets at least the yaw angular velocity K _s at the starting point P _s to zero and the yaw angular velocity K _e at the end point P _e to zero as the first constraint condition. While using the second constraint condition, at least the yaw angular velocity K _s at the start point P _s is set to non-zero, the yaw angular velocity K _e at the end point P _e is set to zero, and the end point P _e The condition is that the yaw angular acceleration K _e ' at is set to zero. Thereby, when the first constraint condition is used, it is possible to appropriately reduce the yaw angular velocity that occurs in the vehicle 1 at the start and end of a lane change. On the other hand, when the second constraint condition is used, the yaw angular velocity generated in the vehicle 1 at the beginning of the lane change can be appropriately made relatively large, while the yaw angular velocity generated in the vehicle 1 at the end of the lane change can be made relatively large. The yaw angular velocity and yaw angular acceleration that occur can be reduced, that is, the lane change operation can be gradually converged.

Furthermore, according to the present embodiment, the ECU 10 determines whether or not there is a following vehicle 3 near the vehicle 1 on the lane to which the vehicle 1 is changing, based on the headway time and the collision margin time. It is possible to accurately judge whether there is a following vehicle 3 whose intention should be recognized.

[Modified example]
In the embodiment described above, the driving route is generated using the state lattice method, but the driving route is not limited to being generated using the state lattice method. In addition to the state lattice method, the travel route may be generated using various known methods (for example, the potential method, the spline interpolation function, the A-star (A*) method, the Dijkstra method, etc.).

Furthermore, in the above-described embodiment, a driving route is generated in which the yaw angular velocity that occurs at the start of a lane change is large, but a driving route is generated in which the yaw angular velocity that occurs strictly at the start timing of a lane change is large. In other examples, a driving route may be generated in which the yaw angular velocity that occurs near the start of the lane change (timing after a certain amount of time has elapsed from the start of the lane change) is generated. .

Further, in the above-described embodiment, an example was shown in which the present invention is applied to a vehicle 1 that uses an engine as a drive source (see FIG. 1), but the present invention also applies to a vehicle that uses an electric motor as a drive source (such as an electric vehicle or a hybrid It is also applicable to cars). In addition, in the embodiment described above, the braking force is applied to the vehicle 1 by the brake device (brake control system 32), but in other examples, the braking force may be applied to the vehicle by regeneration of the electric motor. .

1 vehicle 5 road 10 ECU
21 Camera 22 Radar 23 Vehicle speed sensor 30 Navigation system 100 Vehicle driving support system (driving route generation system)
G _n grid point RC route candidate SP sampling point

Claims (4)

A driving route generation system,
a driving path information acquisition device that acquires driving path information regarding a driving path of a vehicle;
an obstacle information acquisition device that acquires obstacle information regarding obstacles on the travel path;
an arithmetic device configured to generate a travel route for the vehicle to travel on the travel route based on the travel route information and the obstacle information;
The arithmetic device is
When the vehicle changes lanes, it is determined whether or not there is a following vehicle near the vehicle on the lane to which the vehicle is changing, based on the travel path information and the obstacle information;
When it is determined that the following vehicle exists, the yaw angular velocity generated when the vehicle performs a lane change operation is greater than when it is determined that the following vehicle does not exist. configured to generate a driving route;
When it is determined that the following vehicle is present, the arithmetic device is configured to calculate a yaw angular velocity that occurs when the vehicle starts an operation for changing lanes at a higher speed than when it is determined that the following vehicle does not exist. is configured to generate the travel route such that the
The arithmetic device is
A line connecting a starting point according to the current position of the vehicle and an end point determined in front of the vehicle, the x-coordinate and y-coordinate being defined in the direction in which the traveling path extends and the width direction of the traveling path, respectively. Generating the travel route based on the line expressed by an n-dimensional function using coordinates,
If it is determined that the following vehicle does not exist, a first constraint condition of setting at least a yaw angular velocity at the starting point to zero is applied to the n-dimensional function to generate the travel route; When it is determined that the following vehicle exists, the driving route is generated by applying a second constraint condition that at least the yaw angular velocity at the starting point is set to non-zero to the n-th order function. ,
The n-dimensional function is one of a cubic function, a quartic function, and a quintic function.
A driving route generation system characterized by: The arithmetic device is
As the first constraint condition, at least the condition that the yaw angular velocity at the starting point is set to zero, and the yaw angular velocity at the end point is set to zero,
The second constraint condition is at least that the yaw angular velocity at the starting point is set to non-zero, the yaw angular velocity at the end point is set to zero, and the yaw angular acceleration at the end point is set to zero. configured to use
The travel route generation system according to claim 1 . The arithmetic device is
The headway time between the vehicle and the following vehicle is calculated based on the speed of the vehicle and the inter-vehicle distance between the vehicle and the following vehicle included in the obstacle information, and the headway time is less than a predetermined time. In this case, it is determined that the following vehicle exists near the vehicle on the lane to change to , or
Based on the speed of the vehicle, the speed of the following vehicle included in the obstacle information, and the inter-vehicle distance between the vehicle and the following vehicle, the collision margin time between the vehicle and the following vehicle is calculated, and the collision time is calculated. If the free time is less than a predetermined time, it is determined that the following vehicle is present near the vehicle on the lane to which the vehicle is changing, or
The vehicle headway time and the collision margin time are calculated, and if the vehicle headway time is less than a predetermined time and the collision margin time is less than a predetermined time, if the following vehicle is present near the vehicle on the lane to which the vehicle is to be changed. is configured to determine ,
The travel route generation system according to claim 1 or 2 . It is characterized by comprising a control device configured to control the operation of the vehicle so that the vehicle travels along the travel route generated by the travel route generation system according to any one of claims 1 to 3 . Vehicle driving support system.

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