JP5353667B2 - Route creation device - Google Patents

Description

  The present invention relates to a route creation device that creates a travel route of a vehicle.

  2. Description of the Related Art Conventionally, a technique for creating (planning) a moving route of an automobile or the like using a technique called RRT (Rapidly-exploring Random Tree) is known (see Non-Patent Document 1 below). It is possible to create an optimal travel route for avoiding the problem. In RRT, the process of setting a new node is repeated based on points randomly extracted from space (hereinafter also referred to as extraction points), and finally the line segments connecting the nodes are sequentially connected to start the target point from the start point. Create a route to

P. Cheng, Z. Shen and S. M. LaValle, "RRT-Based Trajectory Design for Autonomous Automobiles and Spacecraft," Archives of Control Sciences, Vol. 11, No. 3-4, 2001, pp. 51-78

  In RRT, logic is set so that a target point becomes an extraction point with a certain probability, but since the probability is a fixed value, calculation time may increase in some cases when trying to create a travel route of the vehicle. there's a possibility that.

  In view of the above, an object of the present invention is to provide a route creation device capable of shortening a travel route creation time.

  The route creation device of the present invention is a route creation device that creates a travel route of a vehicle from a start point to a target point by sequentially connecting line segments that connect nodes, and is based on points randomly extracted from space Creating means for creating a travel route by repeatedly performing a process of setting a new node until a node is set within a predetermined range from the target point and sequentially connecting line segments connecting the set nodes; A detecting means for detecting the situation of the vehicle or the surroundings of the vehicle, and a determining means for determining a probability that the target point is a randomly extracted point based on the situation detected by the detecting means. It is characterized by.

  If there is a high probability that the extraction point serving as a reference for establishing a node matches the target point, the node is likely to be generated linearly toward the target point. On the other hand, if the probability is low, the created route is bypassed. Has a tendency toward the target point. Therefore, by determining the probability that the target point is the extraction point based on the situation of the vehicle or its surroundings, the time for the node to be set toward the target point can be adjusted, and as a result, the time required for creating the travel route is shortened It becomes possible to do.

  In the route creation device of the present invention, the detecting means detects the current position and the traveling direction of the vehicle, and the determining means follows the traveling direction of the vehicle based on the current position and the traveling direction of the vehicle detected by the detecting means. The angle between the axis and the axis connecting the vehicle and the target point may be calculated, and the probability may be higher as the calculated angle is smaller.

  In this case, since the probability is set higher as the target point is ahead of the vehicle, it is easy to avoid the extraction point being set in an area where it is difficult to proceed due to the function of the vehicle, and the node becomes the target point. It becomes easy to set towards. As a result, the number of repetitions of the node setting process is reduced, and the travel route creation time can be shortened.

  In the route creation device of the present invention, the detection means detects the position of an obstacle around the vehicle, and the determination means detects an obstacle between the vehicle and the target point based on the position of the obstacle detected by the detection means. It may be determined whether or not there is an obstacle, and when an obstacle exists between the vehicle and the target point, the probability may be lower than that when the obstacle is not.

  In this case, when there is an obstacle between the vehicle and the target point, the probability is set lower than when the obstacle is not, so that the node is easily set to bypass the obstacle. As a result, the number of repetitions of the node setting process is reduced, and the travel route creation time can be shortened.

  According to such a route creation device, since the probability that the target point is the extraction point is determined based on the situation of the vehicle or its surroundings, the time for which the node is set toward the target point can be adjusted, and as a result This makes it possible to shorten the travel route creation time.

It is a figure which shows the structure of the route creation apparatus which concerns on each embodiment. (A), (b) is a figure which shows the procedure of the route creation using RRT. (A)-(c) is a figure which shows the procedure of the route creation using RRT. It is a figure which shows the procedure of the route creation using RRT. It is a figure which shows the example of the relationship between the advancing direction of a vehicle, and a target point. It is a graph which shows the example of the relationship between the angle and probability which are decided based on the advancing direction of a vehicle, and a target point.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
First, the function and configuration of the route creation device 1 according to the first embodiment will be described with reference to FIGS. The route creation device 1 is a device that creates a travel route of a vehicle. As shown in FIG. 1, an obstacle detection device 11, a white line detection device 12, a road detection device 13, a travel condition detection device 14, a car navigation system 15, and A route creation ECU 16 is provided. The route creation device 1 is connected to a driving support ECU 2 that controls the display device 3, the alarm device 4, and the driving support device 5.

  The obstacle detection device 11 includes a millimeter wave radar, a laser radar, and the like, and detects the position of obstacles (things that prevent the vehicle from traveling, such as buildings, guardrails, and pedestrians) around the vehicle. Device. The obstacle detection device 11 executes detection processing at predetermined intervals, and outputs detection results to the route creation ECU 16 as obstacle information as needed.

  The white line detection device 12 includes a camera, an image processing device, and the like, and is a device that detects the position of a white line (lane) attached to the road. The white line detection device 12 executes detection processing at predetermined intervals, and outputs detection results to the route creation ECU 16 as white line information as needed.

  The road detection device 13 includes a laser radar and the like, and is a device that detects the shape of the road. The road detection device 13 executes detection processing at predetermined intervals, and outputs detection results to the route creation ECU 16 as road shape information at any time.

  The traveling state detection device 14 includes a wheel speed sensor, a yaw rate sensor, a steering angle sensor, and the like, and is a device that detects a driving state of the vehicle such as a speed and a steering angle. The traveling state detection device 14 executes detection processing at predetermined intervals, and outputs detection results to the route creation ECU 16 as driving information at any time.

  The car navigation system 15 includes a surrounding environment database and GPS (Global Positioning System), and is a device that executes route guidance to a destination. The car navigation system 15 receives access from the route creation ECU 16 and outputs map information stored in the surrounding environment database and position information indicating the current position and traveling direction of the vehicle obtained by GPS to the route creation ECU 16.

  Each of the detection devices and the car navigation system described above can be said to be means for detecting the situation of the vehicle or its surroundings, which is information for determining the probability (described later) that the target point is the extraction point.

  The route creation ECU 16 is an electronic control unit (ECU) that creates a travel route (target route) of a vehicle from a start point to a target point using a technique called RRT. The route creation ECU 16 includes a probability determination unit (determination unit) 16a and a generation unit (creation unit) 16b as functional components. The probability determining unit 16a is a means for determining the probability P with the target point as the extraction point in the RRT. The creation unit 16b is a means for creating a travel route by setting a node (relay point) from the start point to the target point based on the probability P, and finally connecting line segments connecting the nodes. These components are realized by a predetermined program including the RRT algorithm being read and executed by the ECU.

  For convenience of explanation, the route creation processing (RRT algorithm) of the creation unit 16b will be described first with reference to FIGS. 2 to 4, and then the function of the probability determination unit 16a will be described.

  In a state space C composed of a free space F in which the vehicle can travel and a collision space (obstacle) B in which the vehicle cannot travel, the starting point (tree root node) q_init and the target point q_goal are shown in FIG. Is set as follows. First, the creation unit 16b randomly extracts a point q_rand from the state space C (see FIG. 2B). That is, q_rand is an extraction point. At this time, the creation unit 16b sets the target point q_goal as the extraction point q_rand with the probability P input from the probability determination unit 16a. Subsequently, the creation unit 16b searches for a node q_near closest to the extraction point q_rand from among the nodes on the tree. Immediately after the start of the creation process, the node constituting the tree has only the start point q_init as shown in FIG. 2B, so q_near = q_init.

  Subsequently, the creation unit 16b sets a new node q_new at a point advanced by a certain distance ε from the point q_near toward the point q_rand (see FIG. 3A). This distance ε is referred to as a step size, and the creation unit 16b stores the value ε therein in advance. At this time, if the distance between the points q_rand and q_near is smaller than the step size ε, the creating unit 16b sets the point q_rand as a new node q_new as it is (see FIG. 3B). 3C, when the position of the node q_new is located in the collision space B, the creation unit 16b discards the node q_new and the corresponding extraction point q_rand, and newly extracts the point q_rand. Then start over.

  The creation unit 16b repeats the processing from the extraction of the point q_rand to the setting of the node q_new until the node q_new is set within a predetermined distance λ from the target point q_goal (see FIG. 4). The value λ may be the same as or different from the step size ε. Subsequently, the creation unit 16b creates a travel route R from the start point q_init through the zero or more nodes q_new to the target point q_goal by sequentially connecting line segments connecting the two nodes as shown in FIG. . Then, the creation unit 16b outputs route information indicating the generated travel route R to the driving support ECU 2.

  Next, the probability determining unit 16a will be described with reference to FIGS. In the present embodiment, the probability determination unit 16a determines the probability P based on the positional relationship between the traveling direction of the vehicle and the target point. Specifically, the probability determination unit 16a calculates the absolute coordinates (Xo, Yo, θo) of the vehicle and the absolute coordinates (Xg, Yg) of the target point based on the map information and the position information acquired from the car navigation system 15. Identify. Θo is an angle between the X axis and the traveling direction of the vehicle V. For example, it is assumed that the vehicle V and the target point are positioned as shown in FIG.

Subsequently, the probability determination unit 16a converts the absolute coordinates (Xg, Yg) of the target point into relative coordinates (xg, yg). Here, the relative coordinates of the target point are the coordinates of the target point in the coordinate system in which the traveling direction of the vehicle V is the x axis and the axis (width direction of the vehicle V) orthogonal thereto is the y axis, as shown in FIG. I mean. Conversion from absolute coordinates (Xg, Yg) to relative coordinates (xg, yg) is expressed by the following equation (1).

Subsequently, the probability determination unit 16a calculates an angle B (rad) (see FIG. 5) between an axis (x axis) along the traveling direction of the vehicle V and an axis connecting the vehicle V and the target point by the following equation (2). To do.
B = tan ⁻¹ (| yg | / | xg |) (2)

Subsequently, the probability determination unit 16a determines the probability P by applying the calculation result of the above formula (2) to the correspondence relationship between the angle B and the probability P stored in advance, and outputs the value to the creation unit 16b. . For example, the probability determining unit 16a determines the probability P based on the correspondence relationship between the angle B and the probability P shown in the graph of FIG. In the example of FIG. 6, if the angle B is equal to or greater than B ′, the probability P is fixed to the minimum value Pmin. The correspondence between the angle B and the probability P is set so that the probability P increases as the angle B decreases, that is, as the target point is ahead of the vehicle. The method for determining the probability P is not limited to this. For example, if the angle B is equal to or smaller than a predetermined value, the probability may be P _A, and otherwise, the probability may be P _B (where P _B <P _A ).

  The probability determining unit 16a outputs the probability P determined as described above to the creating unit 16b. In response to this, the creation unit 16b executes the route creation process as described above. The probability determination process is executed only once at the beginning of the process for creating a travel route. Note that the travel route creation process itself can be executed repeatedly (for example, periodically).

  Returning to FIG. 1, the driving support ECU 2 is an ECU that executes control for supporting a driver or driving based on route information. The driving support ECU controls the display device 3, the alarm device 4, and the driving support device 5 based on the input route information.

  Here, the display device 3 includes a meter, a head-up display (HUD), and the like, and is a device that provides information including text and images. The alarm device 4 includes a speaker and is a device that emits voice guidance and an alarm sound. The driving support device 5 includes a brake actuator and an electric power steering (EPS) actuator, and assists driving by automatically performing deceleration and steering.

  A method of using the route information in the driving support ECU 2 is arbitrary. For example, the driving assistance ECU 2 may display the travel route indicated by the route information on the display device 3. Further, the driving support ECU 2 may issue an alarm from the alarm device 4 or activate the driving support device 5 when the deviation between the travel route indicated by the route information and the actual travel route becomes a predetermined value or more. .

  As described above, according to the present embodiment, since the probability P is set higher as the target point is ahead of the vehicle, the extraction point is set in an area where it is difficult to proceed due to the function of the vehicle. Is easily avoided, and the node is easily set toward the target point. As a result, the number of repetitions of the node setting process is reduced, and the travel route creation time can be shortened.

  If there is a high probability that the extraction point q_rand as a reference for providing the node q_new coincides with the target point q_goal, the node q_new is likely to be generated linearly toward the target point. Has a tendency toward the target point q_goal while detouring. Therefore, by determining the probability that the target point is the extraction point based on the situation of the vehicle or its surroundings as described above, the time for which the node q_new is set toward the target point can be adjusted. As a result, the travel route It becomes possible to shorten the creation time.

(Second Embodiment)
Next, the function and configuration of the route creation device 1 according to the second embodiment will be described. Since the difference from the first embodiment is a method for determining the probability P, this point will be particularly described, and the description of other parts will be omitted. Further, since the hardware configuration and functional blocks of the apparatus are the same as those in the first embodiment, description will be made using the same reference numerals as those in the embodiment.

  In the present embodiment, the probability determination unit 16a determines the probability P based on the position of the obstacle. The probability determination unit 16a calculates the position of the obstacle based on at least one of the input obstacle information, white line information, road shape information, driving information, and map information read from the car navigation system 15, for example. . Subsequently, the probability determination unit 16a determines whether or not an obstacle exists on the line segment connecting the vehicle and the target point. Here, the position of the vehicle corresponds to the starting point of the route.

  Then, when any obstacle exists on the line segment, the probability determination unit 16a lowers the current probability P by a predetermined value. At this time, the probability determination unit 16a may increase the probability P by a predetermined value when there is no obstacle on the line segment. In any case, with such a process, when there is an obstacle on the line segment connecting the vehicle and the target point, the probability P is lower than when the obstacle is not. The probability determining unit 16a outputs the probability P corrected in this way to the creating unit 16b.

  As described above, according to the present embodiment, when there is an obstacle between the vehicle and the target point, the probability is set lower than when the obstacle is not, so that the node bypasses the obstacle. It becomes easy to set. As a result, the number of repetitions of the node setting process is reduced, and the travel route creation time can be shortened.

  The present invention has been described in detail based on the embodiments. However, the present invention is not limited to the above embodiment. The present invention can be variously modified without departing from the gist thereof.

  The probability determination unit 16a may determine the probability P by a method combining the first and second embodiments. For example, the probability determining unit 16a provisionally determines the probability P based on the positional relationship between the traveling direction of the vehicle and the target point as in the first embodiment, and then the presence / absence of an obstacle as in the second embodiment. After correcting the probability P based on the above, the corrected probability P may be output to the creating unit 16b.

  The method of mounting the route creation device 1 of each of the above embodiments on the vehicle is arbitrary. For example, the entire route creation device 1 may be mounted on a vehicle to create a movement route of the vehicle, that is, the host vehicle. Even if a part other than the route creation ECU 16 is mounted on the vehicle, a function corresponding to the route creation ECU 16 is embedded in a system outside the vehicle, and the movement route of the vehicle is created by connecting the system and the vehicle through a communication network. Good.

DESCRIPTION OF SYMBOLS 1 ... Route creation apparatus, 11 ... Obstacle detection apparatus (detection means), 12 ... White line detection apparatus (detection means), 13 ... Road detection apparatus (detection means), 14 ... Travel condition detection apparatus (detection means), 15 ... Car navigation system (detection means), 16 ... route creation ECU, 16a ... probability determination unit (determination means), 16b ... creation unit (creation means).

Claims (3)

A route creation device that creates a travel route of a vehicle from a start point to a target point by sequentially connecting line segments connecting nodes,
The process of setting a new node based on randomly extracted points from space is repeatedly executed until a node is set within a predetermined range from the target point, and line segments connecting the set nodes are sequentially connected. Creating means for creating the travel route by:
Detecting means for detecting a situation of the vehicle or a situation around the vehicle;
Determining means for determining a probability that the target point is the randomly extracted point based on the situation detected by the detecting means;
A route creation device comprising: The detecting means detects a current position and a traveling direction of the vehicle;
The determining means calculates an angle between an axis along the traveling direction of the vehicle and an axis connecting the vehicle and the target point based on the current position and the traveling direction of the vehicle detected by the detecting means; The probability increases as the calculated angle decreases.
The route creation device according to claim 1. The detection means detects the position of an obstacle around the vehicle;
The determining means determines whether an obstacle exists between the vehicle and the target point based on the position of the obstacle detected by the detecting means, and determines between the vehicle and the target point. If there is an obstacle in the case, the probability is lower than if it is not,
The route creation device according to claim 1 or 2, wherein

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