JP7183520B2 - Route candidate setting system and route candidate setting method - Google Patents

Description

The present invention relates to a route candidate setting system and a route candidate setting method.

Potential method, spline interpolation function, A star (A*), RRT, state lattice method, etc. are known as algorithms used for setting vehicle route candidates (that is, candidates that can be the target route for actually driving the vehicle). ing. A driving support system using such an algorithm has also been proposed.

In the state lattice method, a large number of grid points are set on the road, and route candidates are set for each grid point. Each route candidate is evaluated for route cost from the viewpoint of obstacle avoidance and the like, and one route candidate judged appropriate as a result of the evaluation is selected as the target route. For example, Patent Literature 1 discloses a driving support system that sets a plurality of route candidates on a grid map and selects one route candidate from these based on travel costs.

WO2013/051081

In recent driving support systems, even when avoiding obstacles, it is desired to set a target route in consideration of the reduction of discomfort given to the passenger and the behavior of the vehicle before and after the avoidance. Therefore, it is necessary to set various route candidates.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and an object of the present invention is to provide a route candidate setting system and a route candidate setting method capable of setting various route candidates.

In order to solve the above-mentioned problems, the present invention provides a route candidate setting system for setting route candidates for a vehicle, comprising: a route information acquisition device for acquiring route information relating to a route; and an arithmetic device for executing arithmetic operations for setting candidates, wherein the arithmetic devices are arranged in a grid pattern when the direction in which the road extends is defined as the x direction and the width direction of the road is defined as the y direction. A function that sets a plurality of calculated grid points on the road, starts from the position of the vehicle at the time of execution of the calculation, extends from a grid point in front of the vehicle in the direction of travel as an end point, and has the y coordinate as a variable of the x coordinate. is configured to define a curve represented by and set the curve as a route candidate, and furthermore, the arithmetic device sets boundary conditions indicating the running state of the vehicle at the start point and the end point, and a boundary having a plurality of boundary conditions A condition set is set, and a curve satisfying each of a plurality of boundary condition sets is set as a route candidate.

According to this configuration, the computing device sets curves that satisfy each of the plurality of boundary condition sets as route candidates. That is, according to this configuration, it is possible to set a plurality of route candidates by a simple method of setting a plurality of boundary condition sets.

In the present invention, preferably, the curve is represented by an nth-order function in which the y-coordinate is the x-coordinate, and the arithmetic unit sets at least n+1 boundary conditions.
where n is a positive integer. A general formula for an nth-order function is expressed using n+1 coefficients. The coefficient may also contain zero.
According to the above configuration, the arithmetic unit can obtain n+1 relational expressions for determining each coefficient by applying at least n+1 boundary conditions. As a result, it becomes possible to specifically define a curve extending from the start point to the end point.

In the present invention, the curve is preferably represented by a quintic function in which the y-coordinate is the x-coordinate.
According to this configuration, by differentiating the quintic function once to three times with respect to the x-coordinate, it is possible to obtain a relational expression that is correlated with the yaw angle, yaw angular velocity, and yaw angular acceleration of the vehicle. The relational expressions make it possible to evaluate the yaw angle, the yaw angular velocity and the yaw angular acceleration of the vehicle. As a result, considering the behavior of the vehicle in the yaw direction, it is possible to set a route candidate that reduces the discomfort that the behavior gives to the passenger.

In the present invention, the boundary conditions preferably include the yaw angular velocity and yaw angular acceleration of the vehicle at the start or end point as zero.
According to this configuration, when the yaw angular velocity and yaw angular acceleration of the vehicle at the starting point are zero, the straightness of the vehicle increases near the starting point. A route candidate set by applying such a boundary condition is useful, for example, when a large acceleration is required in order for the vehicle to quickly overtake a preceding vehicle near the starting point.
Further, when the yaw angular velocity and yaw angular acceleration of the vehicle at the end point are zero, the straightness of the vehicle increases near the end point. Route candidates set by applying such boundary conditions are useful, for example, when attempting to stably stop a vehicle at an end point.

In the present invention, the boundary conditions preferably include the x-coordinate and y-coordinate of the starting point.
According to this configuration, it is possible to reduce the computational load of the computing device and quickly define the curve that satisfies the boundary condition.

In order to solve the above-mentioned problems, the present invention provides a route candidate setting method for setting route candidates for a vehicle, comprising steps of acquiring travel road information relating to a travel road, and setting the route candidates based on the travel road information. and setting a plurality of grid points on the road in the calculation, where the direction in which the road extends is defined as the x direction and the width direction of the road is defined as the y direction. defining a curve that extends from the position of the vehicle at the time of execution of the calculation as the starting point and the grid point as the ending point, and whose y coordinate is represented by a function with the x coordinate as a variable , and sets the curve as a route candidate. setting a boundary condition indicating the state of the vehicle at the start point and the end point; setting a boundary condition set having a plurality of boundary conditions ; and setting each of the plurality of boundary condition sets. and setting the satisfying curve as a route candidate.

ADVANTAGE OF THE INVENTION According to this invention, the route candidate setting system and route candidate setting method which can set various route candidates can be provided.

1 is a configuration diagram of a driving support system according to an embodiment; FIG. FIG. 4 is an explanatory diagram of route candidates; FIG. 4 is an explanatory diagram of route candidates; FIG. 4 is an explanatory diagram of route candidates; FIG. 2 is a flow chart showing calculations executed by an ECU in FIG. 1; FIG.

Embodiments will be described below with reference to the accompanying drawings. In order to facilitate understanding of the description, the same components are denoted by the same reference numerals in each drawing, and overlapping descriptions are omitted.

First, an overview of a driving support system 100, which is an example of a route candidate setting system according to the present invention, will be described with reference to FIGS. 1 and 2. FIG. FIG. 1 is a configuration diagram of a driving support system 100. As shown in FIG. FIG. 2 is an explanatory diagram of route candidates RC.

The driving assistance system 100 is mounted on the vehicle 1 and provides driving assistance control for causing the vehicle 1 to travel along a target route. As shown in FIG. 1, the driving support system 100 includes an ECU (electronic control unit) 10, a plurality of sensors, and a plurality of control systems. 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 the driving operation by the occupant, an acceleration sensor 24, a yaw rate sensor 25, a steering angle sensor 26, an accelerator sensor 27, a brake A sensor 28 is included. Furthermore, the multiple sensors include a positioning system 29 for detecting the position of the vehicle 1 and a navigation system 30 . The multiple control systems include an engine control system 31 , a brake control system 32 and a steering control system 33 .

In addition, as other sensors, a peripheral sonar for measuring the distance and position of peripheral structures with respect to the vehicle 1, a corner radar for measuring the approach of peripheral structures at four corners of the vehicle 1, and a vehicle interior of the vehicle 1 may include an inner camera that captures the

The ECU 10 is an example of an arithmetic device according to the present invention. The ECU 10 is configured by a computer having a CPU, a memory for storing various programs, an input/output device, and the like. The ECU 10 performs various calculations based on signals received from a plurality of sensors, and appropriately controls the engine system, brake system, and steering system for the engine control system 31, brake control system 32, and steering control system 33, respectively. send a control signal to activate the

The ECU 10 performs calculations for specifying a position on the travel road based on the travel road information. The traveling road information is information about the traveling road 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 road information includes, for example, the shape of the road (straight line, curve, curve curvature), width of the road, number of lanes, width of the lane, and the like.

FIG. 2 shows the vehicle 1 running on the road 5. As shown in FIG. The ECU 10 sets a plurality of virtual grid points G _n (n=1, 2, . . . N) on the traveling road 5 in front of the vehicle 1 in the traveling direction by calculation based on the traveling road information. When the direction in which the travel path 5 extends is defined as the x direction and the width direction of the travel path 5 is defined as the y direction, the grid points G _n are arranged in a grid along the x direction and the y direction.

The range in which the ECU 10 sets the grid points _Gn extends a distance L ahead of the vehicle 1 along the travel path 5 . Distance L is calculated based on the speed of vehicle 1 at the time of execution of the calculation. In this embodiment, the distance L is the distance (L=V×t) that is 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. However, the distance L may be a predetermined fixed distance (eg 100m) or it may be a function of velocity (and acceleration). Also, 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 way, it becomes possible to specify the position on the travel path 5 .

Since the running 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 _Gn are arranged along the direction in which the road extends, if the road includes a curved section, the grid points _Gn are arranged along the curve of the curved section.

Further, the ECU 10 performs an operation for setting a route candidate RC (that is, a candidate that can be a target route for actually traveling the vehicle 1) based on the traveling road information and the obstacle information. The obstacle information is information about the presence or absence of obstacles (for example, preceding vehicles, parked vehicles, pedestrians, fallen objects, etc.) on the travel path 5 in the traveling direction of the vehicle 1, their moving directions, their moving speeds, etc. Acquired by camera 21 and radar 22 .

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

Further, the ECU 10 selects one route candidate RC with the lowest route cost from among the plurality of route candidates RC based on a predetermined condition. Specifically, first, as shown in FIG. 2, the ECU 10 sets a plurality of sampling points SP along each route candidate RC and calculates the route cost at each sampling point SP. Next, the ECU 10 selects the route candidate RC with the lowest route cost and sets it as the target route.

The ECU 10 also transmits control signals to 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 route.

The camera 21 is an example of a travel route information acquisition device according to 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 (e.g., preceding vehicles, parked vehicles, pedestrians, roads, lane markings (lane boundaries, white lines, yellow lines), traffic lights, traffic signs, stop lines, intersections, obstacles, etc.). It should be noted that the ECU 10 may acquire information on the object from the outside through traffic infrastructure, vehicle-to-vehicle communication, or the like. As a result, the type, relative position, movement direction, etc. of the object are specified.

The radar 22 is an example of a travel road information acquisition device according to the present invention. The radar 22 measures the positions and velocities of objects (particularly preceding vehicles, parked vehicles, pedestrians, fallen objects on the travel path 5, 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 an object. 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 addition, in this embodiment, instead of the radar 22, a laser radar, an ultrasonic sensor, or the like may be used to measure the distance to the object and the relative speed. Also, a plurality of sensors may be used to configure the position and speed measuring device.

A vehicle speed sensor 23 detects the absolute speed of the vehicle 1 .
The acceleration sensor 24 detects the acceleration of the vehicle 1 (vertical acceleration/deceleration in the longitudinal direction, lateral acceleration/deceleration in the lateral direction).
A yaw rate sensor 25 detects the yaw rate 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 to determine the yaw angle of the vehicle 1 (that is, relative to the x-axis described later). angle formed by the longitudinal direction of the vehicle 1) can be acquired.
The accelerator sensor 27 detects the depression amount of the accelerator pedal.
A 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 stores map information inside and can provide the map information to the ECU 10 . Based on the map information and the current vehicle position information, the ECU 10 identifies roads, intersections, traffic lights, buildings, etc. existing around the vehicle 1 (especially in the traveling direction). Map information may be stored in the ECU 10 .

The engine control system 31 controls the engine of the vehicle 1 . The ECU 10 sends a control signal to the engine control system 31 to change the engine output when the vehicle 1 needs to be accelerated or decelerated.

The brake control system 32 controls the braking device of the vehicle 1 . When the vehicle 1 needs to be decelerated, the ECU 10 sends a control signal to the brake control system 32 to generate braking force.

The steering control system 33 controls the steering device of the vehicle 1 . 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.

Next, calculations for setting route candidates RC will be described with reference to FIGS. 2 to 4. FIG. 3 and 4 are explanatory diagrams of route candidates RC.

As shown in FIGS. 2-4, the route candidate RC extends from the start point P _s to the end point P _e . The starting point P _s is the position of the vehicle 1 when the calculation is executed. The coordinates of the starting point P _s are represented by (x _s , y _s ). In the examples shown in FIGS. 2 to 4, the vehicle 1 is located at the origin of the xy coordinates, so the coordinates of the starting point P _s are (0,0). The end point P _e is one grid point G _n selected from a plurality of grid points G _n , and its coordinates are represented by (x _e , y _e ).

The ECU 10 provisionally defines a quintic function in which the y-coordinate has the x-coordinate as a variable, as shown by the equation f1, as the curve to be set as the route candidate RC. Formula f1 is an example of the nth order function according to the present invention. Also, the curve drawn on the xy coordinates based on the formula f1 is an example of the curve according to the present invention.

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

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

Further, in the following description, as shown in FIG. 3, the angle formed by a straight line 1L extending along the longitudinal direction of the vehicle 1 with respect to the x-axis is referred to as a "yaw angle". Furthermore, the yaw angle at the starting point P _s is H _s and the yaw angle at the end point P _e is _He . The units of the yaw angles H _s and _He are both radians.

The x-coordinate (x _s ) of the starting point P _s and the tangent of the yaw angle H _s at the starting point P _s satisfy the relationship of formula f2. Also, the x-coordinate (x _e ) of the end point P _e and the tangent of the yaw angle H _e at the end point P _e also satisfy the relationship of formula f2. Therefore, the ECU 10 can obtain the relational expressions f7 and f8.

Since the formula f3 indicates the rate of change of y' with respect to x, it is correlated with the yaw angular velocity. Accordingly, the x-coordinate (x _s ) of the starting point P _s and the yaw angular velocity K _s at the starting point P _s approximately satisfy the relationship of formula f3. Also, the x-coordinate (x _e ) of the end point P _e and the yaw angular velocity K _e at the end point P _e generally satisfy the relationship of formula f3. Therefore, the ECU 10 can obtain the relational expressions f9 and f10.

Also, since the formula f4 indicates the rate of change of y'' with respect to x, it is correlated with the yaw angular acceleration. Accordingly, the x-coordinate (x _s ) of the starting point P _s and the yaw angular acceleration K _s ' at the starting point P _s approximately satisfy the relationship of formula f4. Also, the x-coordinate (x _e ) of the end point P _e and the yaw angular acceleration K _e ′ generally satisfy the relationship of formula f4. Therefore, the ECU 10 can obtain the relational expressions f11 and f12.

The ECU 10 appropriately sets a plurality of boundary conditions indicating the state of the vehicle 1 (that is, coordinates, yaw angle, yaw angular velocity, yaw angular acceleration) at each of the start point _Ps and the end point _Pe . The ECU 10 determines the coefficients a to f by applying the boundary conditions 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 start point _Ps to the end point _Pe and is set as the route candidate RC.

FIG. 4 shows the first boundary condition set, the second boundary condition set, and the third boundary condition set when the vehicle 1 (see FIGS. 2 and 3) moves 4 m in the y direction while moving 100 m in the x direction. route candidates RC ₁ , RC ₂ , and RC ₃ set by applying each of . The xy coordinates are set so that the starting point _Ps , which is the position of the vehicle 1 at the time of calculation, is located at the origin.

<First boundary condition set>
The first boundary condition set is
[Boundary condition 1-1] Coordinates of start point P _s [Boundary condition 1-2] Coordinates of end point P _e [Boundary condition 1-3] Yaw angle H _s at start point P _s
[Boundary condition 1-4] Yaw angle H _e at end point P _e
[Boundary condition 1-5] Yaw angular velocity K _s at starting point P _s
[Boundary condition 1-6] Yaw angular velocity K _e at end point P _e
has six boundary conditions of

[Boundary Condition 1-1] and [Boundary Condition 1-2] The ECU 10 substitutes the coordinates (0, 0) of the start point P _s and the coordinates (100, 4) of the end point P _e into the formula f1. Thereby, the ECU 10 can obtain two relational expressions such as the expressions f5 and f6 that are established at the start point P _s and the end point P _e , respectively.

Regarding [Boundary Condition 1-3] and [Boundary Condition 1-4] Further, the ECU 10 determines the x-coordinate (0) of the start point P _s and the tangent of the yaw angle H _s at the start point P _s and the x _- coordinate ( 100) and the tangent of the yaw angle H _e at the end point P _e into equation f2. Thereby, the ECU 10 can obtain two relational expressions such as the expressions f7 and f8 that are established at the start point P _s and the end point P _e , respectively.

[Boundary Condition 1-5] and [Boundary Condition 1-6] Further, the ECU 10 determines the x-coordinate (0) of the start point P _s and the yaw angular velocity K _s at the start point P _s and the x-coordinate (100) of the end point P _e and the yaw angular velocity K _e at the end point P _e are substituted into the equation f3. Thereby, the ECU 10 can obtain two relational expressions such as the expressions f9 and f10 that are established at the start point P _s and the end point P _e , respectively.

Thus, the ECU 10 can obtain a total of six relational expressions by applying the first set of boundary conditions. The ECU 10 determines coefficients a to f by solving these six relational expressions. This makes it possible to specifically define the curve extending from the end point P _e to the end point P _e and set as the route candidate RC ₁ . The route candidate RC ₁ shown in FIG. 4 is set when both the yaw angle H _s and the yaw angular velocity K _s at the start point P _s and the yaw angle _He and the yaw angular velocity K _e at the end point P _e are zero. It is what is done.

The route candidate RC ₁ set by the ECU 10 by applying the first boundary condition set is a route in which the maximum value of the lateral acceleration generated in the vehicle 1 is smaller than the route candidates RC ₂ and RC ₃ described later. . Therefore, the route candidate RC ₁ is useful in cases such as reducing the discomfort given to the occupant by the lateral acceleration.

<Second boundary condition set>
The second set of boundary conditions is
[Boundary condition 2-1] Coordinates of start point P _s [Boundary condition 2-2] Coordinates of end point P _e [Boundary condition 2-3] Yaw angle H _s at start point P _s
[Boundary condition 2-4] Yaw angle H _e at end point P _e
[Boundary condition 2-5] Yaw angular velocity K _s at start point P _s
[Boundary condition 2-6] Yaw angular acceleration K _s ' at starting point P _s
has six boundary conditions of

About [Boundary condition 2-1] to [Boundary condition 2-5] [Boundary condition 2-1] to [Boundary condition 2-5] of the second boundary condition set correspond to [Boundary condition 1- 1] to [boundary conditions 1-5], respectively. Therefore, even when the second boundary condition set is applied, the ECU 10 can obtain the same five relational expressions as when the first boundary condition set is applied.

[Boundary condition 2-6] In the second boundary condition set, [boundary condition 2-6] is set instead of [boundary condition 1-6] of the first boundary condition set. The ECU 10 substitutes the x-coordinate (0) of the starting point P _s and the yaw angular acceleration K _s ' at the starting point P _s into the equation f4. From this, the ECU 10 can obtain one relational expression that holds at the starting point P _s like the expression f11.

Thus, the ECU 10 can obtain a total of six relational expressions by applying the second set of boundary conditions. The ECU 10 determines coefficients a to f by solving these six relational expressions. Thereby, the ECU 10 can specifically define a curve extending from the end point P _e to the end point P _e and set as the route candidate _RC2 . In the route candidate RC ₂ shown in FIG. 4, the yaw angle _{H s ,} the yaw angular velocity K _s , and the yaw angular acceleration K s _' at the start point P s and the yaw angle _He at the end point P _e are all zero. is set when

As is clear from FIG. 4, the route candidate RC ₂ set by applying the second set of boundary conditions has a higher straightness of the vehicle 1 near the starting point P _s than the route candidates RC ₁ and RC ₃ . It has become. This difference is caused by setting the yaw angular acceleration K _s ' at the starting point P _s to zero in [Boundary condition 2-6]. The route candidate _RC2 is useful, for example, when a large acceleration is required in the vicinity of the start point _Ps in order for the vehicle 1 to quickly overtake the preceding vehicle in the vicinity of the start point _Ps .

<Third boundary condition set>
The third boundary condition set is
[Boundary condition 3-1] Coordinates of start point P _s [Boundary condition 3-2] Coordinates of end point P _e [Boundary condition 3-3] Yaw angle H _s at start point P _s
[Boundary condition 3-4] Yaw angle H _e at end point P _e
[Boundary condition 3-5] Yaw angular velocity K _e at end point P _e
[Boundary condition 3-6] Yaw angular acceleration K _e ' at end point P _e
has six boundary conditions of

About [Boundary condition 3-1] to [Boundary condition 3-5] [Boundary condition 3-1] to [Boundary condition 3-5] of the third boundary condition set correspond to [Boundary condition 1- 1] to [boundary conditions 1-4] and [boundary conditions 1-6]. Therefore, even when the third boundary condition set is applied, the ECU 10 can obtain the same five relational expressions as when the first boundary condition set is applied.

[Boundary condition 3-6] In the third boundary condition set, [boundary condition 3-6] is set instead of [boundary condition 1-5] of the first boundary condition set. The ECU 10 substitutes the x-coordinate (100) of the end point P _e and the yaw angular acceleration K _e ′ at the end point P _e into the equation f4. From this, the ECU 10 can obtain a single relational expression, such as the expression f12, which holds at the end point _Pe .

Thus, the ECU 10 can obtain a total of six relational expressions by applying the third set of boundary conditions. The ECU 10 determines coefficients a to f by solving these six relational expressions. Thereby, the ECU 10 can specifically define the curve extending from the end point P _e to the end point P _e and set as the route candidate RC ₃ . _{Route candidate RC 3 shown} in _{FIG .} is set.

As is clear from FIG. 4, the route candidate RC ₃ set by applying the third boundary condition set has a higher straightness of the vehicle 1 near the end point P _e than the route candidates RC ₁ and RC ₂ . It has become. This difference is caused by setting the yaw angular acceleration K _e ' at the end point P _e to zero in [Boundary condition 3-6]. The route candidate _RC3 is useful, for example, when trying to stably stop the vehicle 1 near the end point _Pe .

Next, calculations executed by the ECU 10 when providing driving support control will be described with reference to FIG. 5 . FIG. 5 is a flow chart showing calculations executed by the ECU 10 . The ECU 10 repeatedly executes the calculation shown in FIG. 5 (every 0.05 to 0.2 seconds, for example).

First, in step S<b>1 , the ECU 10 acquires travel route information from the camera 21 , the radar 22 and the navigation system 30 .

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 a plurality of , set grid points G _n (n=1, 2, . . . N). The ECU 10 sets grid points _Gn , for example, every 10 m in the x direction and every 0.875 m in the y direction.

Next, in step S<b>3 , the ECU 10 acquires obstacle information from the camera 21 and the radar 22 . That is, the ECU 10 acquires information about the presence or absence of obstacles on the travel path 5 in the traveling direction of the vehicle 1, the direction of movement of the obstacles, the speed of movement of the obstacles, and the like.

Step S4 includes setting route candidates RC (steps S4a to S4c), setting sampling points SP (step S4d), and calculating the route cost of each route candidate RC (step S4e).

In steps S4a to S4c, the ECU 10 applies the first boundary condition set, the second boundary condition set, and the third boundary condition set as described above, with the grid point G _n as the end point P _e , thereby obtaining 3 set up one route candidate RC.

Next, in step S4d, the ECU 10 sets a plurality of sampling points SP (see FIG. 2). Sampling points SP are set at equal intervals (for example, every 0.2 m) in the x direction along each route candidate RC set in steps S4a to S4c.

Next, in step S4e, the ECU 10 calculates the route cost at each sampling point SP of each route candidate RC. Path costs include costs related to velocity, acceleration, lateral acceleration, path change rate, obstacles, and the like. These costs can be set as appropriate. Generally speaking, path costs include travel costs and safety costs. For example, when traveling on a straight route, the travel distance is short, so the travel cost is small. Also, the movement cost increases as the lateral acceleration increases.

The ECU 10 stores the largest route cost among the route costs calculated for each sampling point SP of each route candidate RC in a memory (not shown) as the route cost of the route candidate RC.

The ECU 10 executes the calculation of step S4 with all grid points G _n (n=1, 2, . . . N) as end points P _e . That is, the total number of route candidate RCs set in step S4 is 3N. The ECU 10 also sets sampling points SP for each of the 3N route candidates RC, and calculates route costs.

Next, in step S5, the ECU 10 sets a target route. Specifically, the ECU 10 selects the route candidate RC with the lowest route cost and sets the route candidate RC as the target route.

Next, in step S6, the ECU 10 transmits control signals to the engine control system 31, the brake control system 32, and the steering control system 33 so that the vehicle 1 travels along the target route.

Next, the operation of the driving support system 100 of this embodiment will be described.

According to this configuration, the ECU 10, which is a computing device, sets curves that satisfy the first boundary condition set, the second boundary condition set, and the third boundary condition set as route candidates RC ₁ , RC ₂ , and RC ₃ . do. That is, according to this configuration, it is possible to set a plurality of route candidates RC by a simple method of setting a plurality of boundary condition sets.

Also, the curve is represented by a quintic function in which the y-coordinate has the x-coordinate as a variable, and the ECU 10 sets at least six boundary conditions.
According to this configuration, six relational expressions for determining the coefficients a to f can be obtained by using at least six boundary conditions. As a result, it becomes possible to specifically define a curve extending from the start point _Ps to the end point _Pe .

Also, the curve is represented by a quintic function in which the y-coordinate has the x-coordinate as a variable.
According to this configuration, by differentiating the quintic function once to three times with respect to the x-coordinate, it is possible to obtain a relational expression that correlates with the yaw angle, yaw angular velocity, and yaw angular acceleration of the vehicle 1 . The relational expression makes it possible to evaluate the yaw angle, yaw angular velocity, and yaw angular acceleration of the vehicle 1 . As a result, considering the behavior of the vehicle 1 in the yaw direction, it is possible to set a route candidate that reduces the discomfort that the behavior gives to the occupant.

In the state lattice method, in which a plurality of grid points arranged in a lattice pattern are set on the road, the number of route candidates to be set is enormous compared to other methods such as the A-star method. Therefore, according to the driving support system 100 using the state lattice method, a more appropriate route candidate is set by considering the yaw angle, yaw angular velocity, and yaw angular acceleration of the vehicle 1 from a huge number of route candidates. becomes possible.

The boundary conditions also include the yaw angular velocities K _{s and} K _e and the yaw angular accelerations K s _' and K _e ' of the vehicle 1 at the start point P _s and the end point P _e as zero.
According to this configuration, when the yaw angular velocity K _s and the yaw angular acceleration K _{s ′} of the vehicle 1 at the starting point P _s are zero, the straightness of the vehicle 1 increases near the starting point P _s . A route candidate RC set by applying such boundary conditions is useful, for example, when a large acceleration is required in order for the vehicle 1 to quickly overtake a preceding vehicle near the start point _Ps .
Further, when the yaw angular velocity _{K e and} the yaw angular acceleration K _e ′ of the vehicle 1 at the end point P e are zero, the straightness of the vehicle 1 increases near the end point P _e . A route candidate RC set by applying such a boundary condition is useful, for example, when trying to stably stop the vehicle 1 at the end point _Pe .

The boundary conditions also include the x- and y-coordinates of the starting point _Ps .
According to this configuration, it is possible to reduce the computational load of the ECU 10 and quickly define a curve that satisfies the boundary condition.

The embodiments of the present invention have been described above with reference to specific examples. However, the invention is not limited to these specific examples. In other words, the scope of the present invention includes any design modifications made by those skilled in the art to these specific examples as long as they have the features of the present invention.

In the above-described embodiment, the ECU 10 _sets all the grid points G _n (n=1, 2, . However, the invention is not limited to this form. For example, the calculation load may be further reduced by appropriately thinning out the grid points G _n serving as the end points P _e based on the acquired obstacle information.

1 vehicle 10 ECU (arithmetic unit)
21 camera (runway information acquisition device)
22 radar (running road information acquisition device)
30 navigation system (running route information acquisition device)
100 driving support system (route candidate setting system)
G _n grid point RC route candidate

Claims (6)

A route candidate setting system for setting route candidates for a vehicle,
a traveling road information acquisition device that acquires traveling road information about the traveling road;
a computation device that performs computation for setting the route candidate based on the travel road information;
When the direction in which the travel path extends is defined as the x direction and the width direction of the travel path is defined as the y direction,
The computing device is
Set multiple grid points arranged in a grid pattern on the road,
A curve extending from the position of the vehicle at the time of execution of the calculation as a starting point and extending from the grid point in front of the traveling direction of the vehicle as an ending point, and having the y coordinate expressed by a function with the x coordinate as a variable, is defined as the curve. Configured to set as a route candidate,
Furthermore, the computing device
setting boundary conditions indicating the running state of the vehicle at the start point and the end point;
setting a boundary condition set having a plurality of said boundary conditions;
configured to set the curve that satisfies each of the plurality of boundary condition sets as the route candidate,
A route candidate setting system characterized by: The curve is represented by an nth-order function in which the y-coordinate is the x-coordinate as a variable,
2. The route candidate setting system according to claim 1, wherein said arithmetic unit sets at least n+1 said boundary conditions. 3. The route candidate setting system according to claim 2, wherein the curve is represented by a quintic function in which the y-coordinate has the x-coordinate as a variable. 4. The route candidate setting system according to claim 3, wherein the boundary conditions include the yaw angular velocity and yaw angular acceleration of the vehicle at the start point or the end point as zero. 4. The route candidate setting system according to any one of claims 1 to 3, wherein said boundary conditions include x and y coordinates of said starting point. A route candidate setting method for setting a route candidate for a vehicle,
obtaining travel path information about the travel path;
and executing an operation for setting the route candidate based on the travel road information;
When the direction in which the travel path extends is defined as the x direction and the width direction of the travel path is defined as the y direction,
In the above calculation,
setting a plurality of grid points on the track;
A step of defining a curve whose starting point is the position of the vehicle at the time of execution of the calculation, whose starting point is the position of the vehicle, whose ending point is the grid point, whose y coordinate is expressed by a function whose x coordinate is the variable, and which is set as the route candidate. and
moreover,
setting boundary conditions that indicate the state of the vehicle at the start point and the end point;
setting a boundary condition set having a plurality of said boundary conditions;
setting the curve that satisfies each of the plurality of boundary condition sets as the route candidate;
A route candidate setting method characterized by comprising :

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