阅读说明：本技术 车辆的行驶控制方法及行驶控制装置 (Vehicle travel control method and travel control device ) 是由 福重孝志 田家智 于 2019-01-22 设计创作，主要内容包括：检测本车辆(V)可行驶的道路区域的行驶路(TA),相对于该行驶路空间,生成将左侧边界线的势值(+P)和右侧边界线的势值(﹣P)设定成相互不同的值的势场,应用势法运算行驶路宽度(W)。在根据该运算的行驶路宽度确定的行驶路径的横向位置相对于以左侧边界线或右侧边界线为基准在行驶路内预先设定的行驶路径的横向位置存在差异的情况下,修正该部分的势值,再次生成设定为修正后的势值的势场,对其应用势法生成行驶路径(TR),并按照生成的行驶路径执行车辆的自动行驶控制。(A travel path (TA) of a road area in which a host vehicle (V) can travel is detected, a potential field in which a potential value (+ P) of a left boundary line and a potential value (-P) of a right boundary line are set to mutually different values with respect to the travel path space is generated, and a travel path width (W) is calculated by applying a potential method. When the lateral position of the travel path specified on the basis of the calculated travel path width differs from the lateral position of the travel path preset in the travel path with reference to the left side boundary line or the right side boundary line, the potential value of the part is corrected, the potential field set to the corrected potential value is generated again, the travel path (TR) is generated by applying the potential method to the potential field, and the automatic travel control of the vehicle is executed according to the generated travel path.)

1. A running control method of a vehicle,

left-side traveling road boundary information related to a left-side boundary line and right-side traveling road boundary information related to a right-side boundary line are acquired as traveling roads of a road area on which the host vehicle can travel,

a potential field in which a left side boundary line of the left side traveling road boundary information becomes a first potential value and a right side boundary line of the right side traveling road boundary information becomes a second potential value different from the first potential value is generated in a space of a traveling road,

calculating potential values of the potential fields, calculating a width of a driving road according to the calculated potential values,

comparing a lateral position of a travel path preset in the travel path with reference to the left or right boundary line with a lateral position of the travel path determined based on the calculated travel path width, and calculating a difference therebetween,

correcting the first potential value and/or the second potential value so that an absolute value of a difference of the calculation becomes a predetermined value or less,

generating a corrected potential field in which a left boundary line of the left traveling road boundary information becomes a corrected first potential value and a right boundary line of the right traveling road boundary information becomes a corrected second potential value in a space of a traveling road,

calculating the potential value of the corrected potential field,

generating a traveling path on which the host vehicle travels on the basis of the calculated equipotential lines of potential values,

and executing automatic running control of the vehicle according to the generated running path.

2. The running control method of a vehicle according to claim 1,

with respect to the left-side traveling road boundary information and the right-side traveling road boundary information,

detecting first traveling path boundary information in a horizontal plane of a road area on which the host vehicle can travel, based on current position information of the host vehicle and map information defining the road boundary information,

acquiring objects and road conditions around the vehicle as surrounding information, detecting second traveling road boundary information in a horizontal plane of a road area where the vehicle can travel based on the surrounding information,

integrating the first driving road boundary information and the second driving road boundary information to generate integrated driving road boundary information,

and separating the integrated driving road boundary information into left driving road boundary information and right driving road boundary information to obtain the information.

3. The running control method of a vehicle according to claim 1 or 2,

the preset lateral position of the travel path is any one of a center position of the travel path in the lateral direction, a position of a first predetermined distance in the left direction from a right boundary line of the travel path, or a position of a second predetermined distance in the right direction from a left boundary line of the travel path.

4. The running control method of a vehicle according to claim 3,

the lateral position of the travel path associated with the road environment information on which the own vehicle travels is stored in advance,

road environment information on which the vehicle is traveling is acquired, and the lateral position of the travel route associated with the road environment information is extracted from the stored lateral positions.

5. The running control method of a vehicle according to claim 3,

calculating frequencies of traveling directions of the left-side traveling road boundary information and the right-side traveling road boundary information, respectively,

and extracting the lateral position of the travel route with reference to the less frequent one of the left side travel route boundary information and the right side travel route boundary information.

6. The running control method of a vehicle according to any one of claims 1 to 5,

the potential values of the potential field use an approximate solution of the laplace equation.

7. The running control method of a vehicle according to claim 6,

the potential value of the potential field converts the left-side driving road boundary information and the right-side driving road boundary information into broken line information respectively,

a harmonic function defined by the position, direction and length of each line segment of the polygonal line information is set as a basis function, and an approximate solution of linear combination of the functions is used.

8. The running control method of a vehicle according to claim 7,

the potential value of the potential field sets a horizontal plane to be an object as a complex plane and converts road boundary information into complex information,

the basis functions are set as complex regular functions, using complex potentials that are approximate solutions to their linear combination.

9. The running control method of a vehicle according to claim 8,

when z is set to a complex variable, the basis function is set to f (z) ═ In (z 1-z) + In { (z 1-z)/(z 0-z) } (z 0-z)/(z 1-z 0).

10. The running control method of a vehicle according to claim 7,

and selecting the middle point of each line segment of the broken line information as an application place of the Dirichlet boundary condition, and obtaining the coefficient of the linear combination by applying a substitute charge method.

11. A travel control device for a vehicle, which generates a travel route of the vehicle, controls at least one of a steering device, a power device, and a brake device on the basis of the travel route, and executes automatic travel control,

the travel control apparatus acquires left-side travel lane boundary information relating to a left-side boundary line and right-side travel lane boundary information relating to a right-side boundary line as travel lanes of a road region on which the host vehicle can travel,

a potential field in which a left side boundary line of the left side traveling road boundary information becomes a first potential value and a right side boundary line of the right side traveling road boundary information becomes a second potential value different from the first potential value is generated in a space of a traveling road,

calculating potential values of the potential fields, calculating a width of a driving road according to the calculated potential values,

comparing a lateral position of a travel path preset in the travel path with reference to the left or right boundary line with a lateral position of the travel path determined based on the calculated travel path width, and calculating a difference therebetween,

correcting the first potential value and/or the second potential value so that an absolute value of a difference of the calculation becomes a predetermined value or less,

generating a corrected potential field in which a left boundary line of the left traveling road boundary information becomes a corrected first potential value and a right boundary line of the right traveling road boundary information becomes a corrected second potential value in a space of a traveling road,

calculating the potential value of the corrected potential field,

generating a traveling path on which the host vehicle travels on the basis of the calculated equipotential lines of potential values,

and executing automatic running control of the vehicle according to the generated running path.

Technical Field

The present invention relates to a vehicle travel control method and a vehicle travel control device.

Background

As a travel path generating device used for automatic driving of a vehicle or the like, there is known a lower travel path generating device that acquires peripheral information of a host vehicle and a travel state of the host vehicle, identifies a travelable area and a non-travelable area of the host vehicle on the basis of a road width, a road shape, an obstacle, and the like acquired on the basis of the peripheral information, sets a curvature of a travel path on the basis of a vehicle speed and a target lateral acceleration of the host vehicle in the identified travelable area, and sets a coefficient of a vector basis function used as a kernel function in a support vector machine as a curvature parameter on the basis of the curvature (patent document 1). Then, the support vector machine of the travel route generation device generates the travel route of the vehicle based on the set curvature parameter.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2015-16799

Problems to be solved by the invention

In the above-described conventional technique, a feature point closest to the recognition surface among feature points belonging to the left and right categories of the road is set as a support vector, the recognition surface is generated so that the distance between the support vector and the recognition surface becomes maximum, and the generated recognition surface is set as a travel route. That is, the approximate center in the lateral width direction of the region of the road identified as drivable is set as the driving path. Therefore, for example, when an obstacle, for example, a parked vehicle, is scattered only on the roadside on the left side of a wide road, a wavy travel path is generated to return to the center of the road only in a range where no obstacle is present, and the passenger may feel uncomfortable.

Disclosure of Invention

The present invention has been made to solve the problem of providing a vehicle travel control method and a vehicle travel control device that eliminate discomfort of a passenger and enable smooth automatic travel control.

Means for solving the problems

In the present invention, a travel path of a road region on which a host vehicle can travel is detected, a potential field in which a potential (potential) value of a left side boundary line and a potential value of a right side boundary line are set to different values with respect to the travel path space is generated, and a travel path width is calculated by applying a potential method. When the lateral position of the travel path specified based on the calculated travel path width differs from the lateral position of the travel path preset in the travel path with reference to the left side boundary line or the right side boundary line, the potential value of the portion is corrected, the potential field set to the corrected potential value is generated again, the travel path is generated by applying the potential method to the potential field, and the automatic travel control of the vehicle is executed according to the generated travel path. Thus, the above problems are solved.

Effects of the invention

According to the present invention, since the travel route is generated in accordance with the lateral position of the travel route set in advance, it is possible to eliminate the sense of discomfort of the passenger and realize smooth automatic travel control.

Drawings

Fig. 1 is a block diagram showing an embodiment of a vehicle travel control device according to the present invention.

Fig. 2 is a block diagram showing a configuration of the travel path width calculation unit shown in fig. 1.

Fig. 3 is a block diagram showing a configuration of the travel route calculation unit shown in fig. 1.

Fig. 4 is a flowchart showing a processing procedure executed in the travel control device of the vehicle shown in fig. 1.

Fig. 5 is a plan view of the travel path for explaining the processing of steps S1 to S4 in fig. 4.

Fig. 6 is a diagram showing potential fields and equipotential lines for explaining the processing in steps S5 to S6 in fig. 4.

Fig. 7 is a graph showing potential values of a cross section along line VII-VII in fig. 6 for explaining the processing of step S7 in fig. 4.

Fig. 8 is a graph showing potential values of a cross section along line VII-VII in fig. 6 for explaining an example of the processing in steps S8 to S10 in fig. 4.

Fig. 9 is a graph showing potential values of a cross section along line VII-VII in fig. 6 for explaining another example of the processing in steps S8 to S10 in fig. 4.

Fig. 10 is a diagram showing an example of a control map stored in the lateral position command unit in fig. 1.

Fig. 11 is a diagram showing potential fields and equipotential lines for explaining the processing in step S12 in fig. 4.

Fig. 12 is a diagram showing potential fields and equipotential lines for explaining the processing in step S13 in fig. 4.

Fig. 13 is a plan view showing an example of a scene that is a premise of a travel route generated using the travel control device for a vehicle of the present invention.

Fig. 14 is (a) a plan view for explaining processing executed by the travel control device for a vehicle according to the present invention with respect to the scenario of fig. 13.

Fig. 15 is a plan view (second view) for explaining processing executed by the travel control device for a vehicle according to the present invention with respect to the scenario of fig. 13.

Fig. 16 is a plan view (third) for explaining processing executed by the travel control device for a vehicle according to the present invention with respect to the scenario of fig. 13.

Detailed Description

Fig. 1 is a block diagram showing a configuration of a vehicle travel control device VTC according to the present embodiment. The vehicle travel control device VTC according to the present embodiment is also an embodiment of a vehicle travel control method according to the present invention. As shown in fig. 1, a vehicle travel control device VTC according to the present embodiment includes: travel path boundary acquisition units 1 to 5, a travel path boundary integration unit 6, a road environment recognition unit 7, a lateral position command unit 8, a boundary condition setting unit 9, a travel path width calculation unit 10, a travel path calculation unit 11, and a travel path following control unit 12.

Of these units, the driving road boundary acquisition units 1 to 5 are configured by various sensors as described later. The travel path boundary integrating unit 6, the road environment recognizing unit 7, the lateral position command unit 8, the boundary condition setting unit 9, the travel path width calculating unit 10, the travel path calculating unit 11, and the travel path following control unit 12 are configured by one or more computers and software installed in the computers. The computer is composed of a ROM in which a program for causing respective units such as the travel path boundary integrating unit 6, the road environment recognizing unit 7, the lateral position command unit 8, the boundary condition setting unit 9, the travel path width calculating unit 10, the travel path calculating unit 11, and the travel path following control unit 12 to function, a CPU that executes the program stored in the ROM, and a RAM that functions as an accessible storage device. Further, as the operation circuit, an MPU, a DSP, an ASIC, an FPGA, or the like can be used instead of or together with the CPU.

The travel path boundary acquisition units 1 to 5 detect various types of information for acquiring left-side travel path boundary information related to a left-side boundary line and right-side travel path boundary information related to a right-side boundary line of a travel path TA of a host vehicle V to be controlled by automatic travel control.

The traveling road boundary acquisition unit 1 acquires the own vehicle position information of the own vehicle position detector mounted on the own vehicle and the three-dimensional high-precision map information stored in the map database, and outputs these pieces of information to the traveling road boundary integration unit 6 and the road environment recognition unit 7. The vehicle position detector is configured by a GPS unit, a gyro sensor, a vehicle speed sensor, and the like, and detects electromagnetic waves transmitted from a plurality of satellite communications by the GPS unit to periodically acquire position information of the vehicle, and detects current position information of the vehicle based on the acquired position information of the vehicle, angle change information acquired from the gyro sensor, and a vehicle speed acquired from the vehicle speed sensor. The three-dimensional high-accuracy map information stored in the map database is three-dimensional map information based on a road shape detected when the vehicle travels on an actual road using the data acquisition system, and is map information in which detailed and high-accuracy position information such as a junction point, a branch point, a toll booth, a reduction position of the number of lanes, a service area/parking area, and the like of the road is associated with the map information as three-dimensional information.

The traveling road boundary acquisition unit 2 acquires obstacle information (LRF information) by a Laser Range Finder (LRF) provided at the front of the vehicle, and outputs the information to the traveling road boundary integration unit 6 and the road environment recognition unit 7. The laser range finder irradiates a laser beam, which is an output wave for distance measurement, onto an area ahead of a vehicle and detects a reflected wave (probe wave) of the laser beam, thereby generating a range signal indicating a relative position between an object target (the object target is, for example, another vehicle on a traveling road on which the vehicle travels, a two-wheeled vehicle, a bicycle, a pedestrian, a lane dividing line on the traveling road, a curb on a roadside, a guardrail, a wall surface, a embankment, or the like) around the vehicle and the vehicle.

The traveling road boundary acquisition unit 3 acquires obstacle information (radar information) using a radar device using millimeter waves or ultrasonic waves, and outputs the information to the traveling road boundary integration unit 6. The radar device irradiates a millimeter wave or an ultrasonic wave to the front of the vehicle, scans a predetermined range around the vehicle, and detects obstacles such as other vehicles, two-wheeled vehicles, bicycles, pedestrians, curbs, guard rails, wall surfaces, and embankments existing around the vehicle. For example, the radar device detects the relative position (direction) between the obstacle and the host vehicle, the relative speed of the obstacle, the distance from the host vehicle to the obstacle, and the like as the surrounding situation of the host vehicle.

The traveling road boundary acquisition unit 4 acquires obstacle information (camera information) by a camera provided in front of the vehicle or the like, and outputs the information to the traveling road boundary integration unit 6. The camera is an image sensor that captures a predetermined range in front of the vehicle and acquires image data, and is constituted by, for example, a CCD wide-angle camera provided at an upper portion of a front window in the vehicle cabin. The camera may be a stereo camera or an omni-directional camera, and may include a plurality of image sensors. The camera detects a road existing ahead of the vehicle and a structure, a road sign, a sign, another vehicle, a two-wheeled vehicle, a bicycle, a pedestrian, and the like around the road as a surrounding situation of the vehicle based on the acquired image data.

The traveling road boundary acquisition unit 5 acquires obstacle information (panoramic surveillance (registered trademark) AVM information) by using cameras provided around the entire periphery of the front, rear, and side of the vehicle, and outputs the information to the traveling road boundary integration unit 6. The camera is an image sensor that captures an image of the entire periphery of the vehicle and acquires image data, and is composed of, for example, a CCD wide-angle camera provided on the upper portion of a front window, left and right rear-view mirrors, a trunk lid, and the like in the vehicle cabin. The camera detects a road around the vehicle, a structure around the road, a road sign, a sign, another vehicle, a two-wheeled vehicle, a bicycle, a pedestrian, and the like as a surrounding situation of the vehicle, based on the acquired image data.

The travel path boundary acquisition units 1 to 5 described above need not be provided in their entirety, and at least one of the travel path boundary acquisition unit 1, the travel path boundary acquisition unit 2, or the travel path boundary acquisition unit 3, and the travel path boundary acquisition unit 4, or the travel path boundary acquisition unit 5 may be provided. Since the traveling road boundary acquisition unit 1 acquires the current position information of the own vehicle and the three-dimensional high-accuracy map information in the vicinity thereof, it is possible to recognize the shape of the road other than the obstacle in the vicinity of the own vehicle. Further, since the road boundary acquisition unit 2 or the road boundary acquisition unit 3 scans with radar light or the like, it is possible to recognize the presence or absence of a distant obstacle. On the other hand, since the traveling road boundary acquisition unit 4 or the traveling road boundary acquisition unit 5 performs imaging using an image sensor or the like, it is possible to recognize not only the presence or absence of an obstacle but also the type thereof.

The travel path boundary integrating unit 6 generates left side travel path boundary information related to a left side boundary line and right side travel path boundary information related to a right side boundary line of a travel path which is a road region where the host vehicle can travel, based on the information acquired by the travel path boundary acquiring units 1 to 5. That is, the first travel path boundary information in the horizontal plane of the road area on which the host vehicle can travel is detected from the current position information of the host vehicle acquired by the travel path boundary acquisition unit 1 and the map information defining the road boundary information. At the same time, the objects and road conditions around the host vehicle acquired by the driving road boundary acquisition units 2 to 5 are acquired as the surrounding information, and the second driving road boundary information in the horizontal plane of the road region where the host vehicle can travel is detected from the surrounding information.

In the present specification, the term "road" refers to a road itself that is actually present regardless of the presence or absence of an obstacle and is included in map information and that is provided for the passage of vehicles and humans. In contrast, in the present specification, the "travel path" refers to an area on a road on which the host vehicle can travel, that is, an area on a road on which the host vehicle can travel, excluding an obstacle. Therefore, the travel path boundary integrating unit 6 detects the first travel path boundary information on the "road" acquired by the travel path boundary acquiring unit 1, and detects the second travel path boundary information on the "travel path" acquired by the travel path boundary acquiring units 2 to 5. The travel path boundary integrating unit 6 integrates the first travel path boundary information and the second travel path boundary information to generate integrated travel path boundary information, and further separates the integrated travel path boundary information into left side travel path boundary information and right side travel path boundary information. In the present specification, "left side", "right side" and "lateral direction" refer to the left side, right side and lateral direction when the traveling direction of the host vehicle is the front.

Fig. 13 is a plan view showing an example of a road on which the vehicle V travels, and shows a left lane in a country regulated by the law of left-hand traffic such as japan and the uk. In the case of this scene, the travel path boundary integration unit 6 acquires the current position of the vehicle V by the travel path boundary acquisition unit 1, specifically acquires latitude and longitude information by the GPS unit, and acquires road information around the vehicle V, specifically the environment or attribute of the road R (country information, position information of the road left end RL, position information of the road right end RR, width of the road R, expressway/ordinary road/other road types, etc.) from the three-dimensional high-precision map information. At the same time, the traveling road boundary integrating unit 6 acquires position information of obstacles such as other vehicles, two-wheeled vehicles, bicycles, pedestrians, curbs, guard rails, wall surfaces, and embankments present around the host vehicle V by using the traveling road boundary acquiring units 2 to 5.

The travel path boundary integrating unit 6 subtracts the obstacle existing region identified based on the position information of the obstacle acquired by the travel path boundary acquiring units 2 to 5 from the region of the road R identified based on the current position information of the host vehicle V acquired by the travel path boundary acquiring unit 1 and the three-dimensional high-accuracy map information of the surroundings thereof, and calculates the travel path TA on which the host vehicle V can travel. Then, the travel path boundary integrating unit 6 calculates left travel path boundary information indicating the left boundary EL and right travel path boundary information indicating the right boundary ER based on the area information of the travel path TA calculated in this way. In other words, in the scenario shown in fig. 13, the traveling road boundary acquisition units 2 to 5 acquire that 3 stationary obstacles (parked vehicles) V1, V2, and V3 are present in the left side portion of the road R, and therefore the left side boundary line EL becomes a line indicated by a broken line, while the right side boundary line ER becomes the same line as the right end RR of the road because no obstacle is present in the right side portion of the road R. The travel path boundary integrating unit 6 holds an aggregate of the left travel path boundary information on the left boundary line EL and the right travel path boundary information on the right boundary line ER converted into the linear fold line information as shown in fig. 5, regardless of the relatively simple road shape shown in fig. 13 or the complicated road shape shown in fig. 5.

Returning to fig. 1, the road environment recognition unit 7 recognizes the road environment and the like in which the host vehicle V is currently traveling, based on the current position information of the host vehicle V acquired by the traveling road boundary acquisition unit 1, the three-dimensional high-accuracy map information of the surroundings thereof, and the position information of the obstacle acquired by the traveling road boundary acquisition unit 2. Specifically, as shown in fig. 10, it is recognized whether the road environment is a lane in which there are many parked vehicles that park on either of the right and left sides of the road R, the country information on whether the driving regulation of the automobile is left-driving or right-driving, the frequency of left-side driving lane boundary information on the left side boundary EL, and the frequency of right-side driving lane boundary information on the right side boundary ER. Fig. 10 is a diagram showing an example of the control map stored in the lateral position command unit 8 in fig. 1.

The lateral position command unit 8 is a unit that sets in advance the lateral position of the travel path TA suitable for the travel of the vehicle V according to the road environment. For example, in japan, the vehicle width of a passenger car is 1.4 to 2.5m, and the width (width) of a road R of one lane is defined to be about 3.5 m. However, there are wide roads of 5 to 6m level depending on countries including japan, and there are not few roads on which roadside parking is permitted. Therefore, in the lateral position command unit 8 of the present embodiment, as to whether or not the road environment is a lane in which there are many parking vehicles parking at the roadside, the three-dimensional high-precision map information acquisition by the traveling road boundary acquisition unit 1 is not the parking prohibition, and the LRF information acquisition unit 2 acquires whether or not there is actually a parking vehicle. Further, country information during traveling of the vehicle V is acquired from the three-dimensional high-accuracy map information of the traveling road boundary acquisition unit 1, and whether the vehicle is traveling on the left or right side is identified. Further, as another condition, the frequency of the left-side traveling lane boundary information of the left boundary line EL and the frequency of the right-side traveling lane boundary information of the right boundary line ER acquired by the traveling lane boundary integrating unit 6 are acquired, and it is recognized which of the left boundary line EL and the right boundary line ER the obstacle is present. The frequency of the left-side traveling lane boundary information and the frequency of the right-side traveling lane boundary information are frequencies of the zigzag lines extending in the extending direction of the road R (the vertical direction in fig. 13) if the left-side boundary line EL shown in fig. 13 is used. That is, the frequencies of the left boundary EL and the right boundary ER when the lateral variation is taken as the amplitude and the direction along the road R is taken as the time are the frequencies of the lateral variation per unit distance in the direction along the road R. When the frequency is high, the number of obstacles is large, and when the frequency is low, the number of obstacles is small.

Further, the lateral position command unit 8 outputs a command to set the position 1.5m leftward from the right end of the travel path TA as the vehicle width center of the vehicle V and to automatically control the travel when the road environment is a lane where the parked vehicle is located on the roadside, based on the road environment recognized by the road environment recognition unit 7, the country information, and other conditions, and the control map shown in fig. 10 stored in the lateral position command unit 8, and when the country is recognized as the country where the vehicle travels on the left side based on the country information, the command is output to set the position 1.5m rightward from the left end of the travel path TA as the vehicle width center of the vehicle V and to automatically control the travel. Similarly, when the road environment is a lane where the parked vehicle is located at a roadside and the country information is not obtained, the lateral position command unit 8 acquires the frequency of the left-side traveling road boundary information of the left boundary line EL and the frequency of the right-side traveling road boundary information of the right boundary line ER acquired by the traveling road boundary integrating unit 6, and outputs a command so as to set a position 1.5m rightward from the left end of the traveling road TA as the vehicle width center of the host vehicle V and automatically travel control the vehicle when the frequency of the left-side traveling road boundary information is small, and outputs a command so as to set a position 1.5m leftward from the right end of the traveling road TA as the vehicle width center of the host vehicle V and automatically travel control the vehicle when the frequency of the right-side traveling road boundary information is small. In addition, when the road environment is not a road on which the parked vehicle is located on a roadside, a command is output so as to automatically control the traveling of the vehicle such that the center position of the traveling path TA coincides with the center of the vehicle width of the host vehicle V.

Returning again to fig. 1, the travel path width calculation unit 10 acquires the integrated travel path boundary information (including the left side travel path boundary information and the right side travel path boundary information) calculated by the travel path boundary integration unit 6, and calculates the travel path width W of the travel path TA ahead of the host vehicle V. Fig. 2 is a block diagram showing a specific configuration of travel path width calculation unit 10 in fig. 1, and fig. 5 is a plan view showing integrated travel path boundary information (including left side travel path boundary information and right side travel path boundary information) calculated by travel path boundary integration unit 6.

As shown in fig. 2, the traveling road width calculation unit 10 includes a potential value calculation unit 101, an equipotential line calculation unit 102, and a gradient calculation unit 103, reads left traveling road boundary information on a left boundary line EL and right traveling road boundary information on a right boundary line ER, calculates a traveling road width W at predetermined intervals with respect to the traveling direction of the host vehicle V, and outputs the traveling road width W to the boundary condition setting unit 9.

Fig. 6 is a diagram showing a result of calculating a potential value of a potential field in which a left side boundary line EL of left side traveling lane boundary information is generated to have a first potential value (+3V in the example shown in the figure) and a right side boundary line ER of right side traveling lane boundary information is generated to have a second potential value (+3V in the example shown in the figure) different from the first potential value (+3V) in a two-dimensional space (x-y plane) of a traveling lane TA by using an alternative charge method (also referred to as a charge superposition method). The equipotential lines (equipotential lines) of the electric field are shown in the case where a voltage of +3V is applied to the left side boundary line EL and a voltage of-3V is applied to the right side boundary line ER by applying an alternative charge method using computer simulation in a two-dimensional space in which the travel path TA exists between the left side boundary line EL shown by an aggregate of a plurality of broken lines and the right side boundary line ER shown by an aggregate of the same plurality of broken lines. That is, fig. 6 shows the result of calculating the potential value, which is the solution of the laplace equation, by the alternative charge method in the two-dimensional space of the travel path TA formed between the left side boundary line EL and the right side boundary line ER.

Fig. 7 is a graph showing potential values (electric charges) in a section along line VII-VII, which is a section of the traveling path TA shown in fig. 6. The vertical axis of fig. 7 has a potential value "+ P" corresponding to +3V in fig. 6, and the vertical axis of fig. 7 has a potential value "-P" corresponding to-3V in fig. 6. In fig. 7, the present inventors have confirmed that the gradient k of the potential value from the left side boundary line EL to the right side boundary line ER is substantially constant, and therefore, when the potential value P, the travel path width W, and the gradient k are used, kW is established as 2P from the graph of fig. 7, and the travel path width W can be calculated as 2P/k from the travel path width W.

Here, the laplace equation is a differential equation for solving a potential field in a natural steady state (a state that does not change with time, that is, a state that has no time-variant), and includes, for example, a diffusion equation for heat conduction related to temperature distribution in a solid body in contact with a heat source and an equation for solving a gravitational potential of a gravitational field in addition to an electrostatic potential in a uniform medium having no charge distribution as shown in fig. 6. Specifically, the quadratic function E of the two-dimensional space (x, y) of the traveling path TA as in the present embodiment meansThe equation of (1).

In addition, when calculating the solution of the laplace equation, it is possible to calculate the solution using a function (hereinafter, a harmonic function) that can perform second order continuous differentiation satisfying the laplace equation. That is, with respect to the quadratic function E of the two-dimensional space (x, y) of the traveling path TA as in the present embodiment, E ═ ax + by + c, and E ═ aIn (√ x (x) is²+y²) Becomes a harmonic function (where a, b, and c denote constant numbers, and In denotes a natural logarithm). Further, the harmonic function assumes a function that can be continuously differentiated in the second order, but can also be differentiated in the infinite order. Here, the traveling as in the present embodimentIn the case of two-dimensional space (x, y) of road TA, there is a condition thatPair wise sub-harmonic function E, F of the equation of (a). The complex function G (x, y) + iF (x, y) obtained by using the paired function E, F is one of the harmonic functions satisfying the laplace equation, and is called a regularization function.

The potential value calculation unit 101 shown in fig. 2 applies an alternative charge method to the two-dimensional space (x-y plane) of the travel path TA to obtain a solution of the laplace equation relating to the electric field. Specifically, a harmonic function defined by the position, direction, and length of a line segment of the fold line information of each of the left-side traveling road boundary information and the right-side traveling road boundary information is used as a basis function, and an approximate solution of linear combination of these functions is used. Here, the midpoint of each line segment of the polygonal line information is selected as an application location of the dirichlet boundary condition, and a linear combination coefficient is obtained by applying the alternative charge method. More specifically, the electric charge (potential value) at all or a part of the two-dimensional space (x-y plane) can be obtained by using the complex potential as an approximate solution of the linear combination of the complex potential and the base function, which is obtained by converting the traveling road boundary information into the complex information by setting the two-dimensional space (x-y plane) of the traveling road TA as the complex plane. In addition, In the complex regularization function as a basis function, z is set to a complex variable and defined as f (z) ═ In (z 1-z) + In { (z 1-z)/(z 0-z) } (z 0-z)/(z 1-z 0). In this way, if the travel path TA to be subjected to the potential field is set to a complex plane, and the left side boundary information of the left side boundary line EL and the right side boundary information of the right side boundary line ER are converted into complex information, the gradient k is easily obtained, and therefore, the gradient calculation unit 103 calculates the travel path width W from the travel path width W shown in fig. 7 as 2P/k, and outputs the travel path width W to the boundary condition setting unit 9.

However, when the potential value calculation unit 101 obtains all the electric charges (potential values) on the x-y plane of the traveling path TA, the calculation load is large and the calculation time is also long. Therefore, the equipotential line calculating unit 102 searches for a position to be a reference for equalizing the electric charges (potential values), and obtains an equipotential line (equipotential line). For example, in the example of the traveling path TA shown in fig. 6, an electric field in which +3V is applied to the left side boundary line EL and a voltage of-3V is applied to the right side boundary line ER is generated as a potential field, and therefore, the center point of the traveling path TA, which is a position of 0V that is an intermediate value of the electric field, is searched along the traveling direction of the host vehicle V. Fig. 11 is a plan view for explaining a method of searching for such equipotential lines.

The equipotential line calculating unit 102 presets a position to be a starting point of a center line of the travel path TA on the travel path TA located ahead of the host vehicle V in the left diagram of fig. 11, and obtains a center point of the true travel path TA by using the newton method. Further, newton method (both referred to as newton-raphson method) is a root-finding algorithm for an iterative method of solving an equation system by numerical calculation, that is, an algorithm for obtaining a preset initial value x_nThe intercept between the tangent of the function of (a) and the potential P is 0, which is set to x_n+1Then, the value x is obtained_n+1The intercept between the tangent of the function of (a) and the potential P is 0, which is set to x_n+2By repeating this process, the start position TR0 of the center point of the actual travel path TA is obtained.

If the true starting point position TR0 of the center line of the travel path TA is obtained by the newton method described above, the equipotential line calculation portion 102 obtains the center point of the travel path TA at a position TR1 located a predetermined distance forward with respect to the traveling direction of the host vehicle V by using the quartic longge-kuta method (RK4), as shown in the right diagram of fig. 11. Here, the quartic longge-kutta method (RK4) is a numerical analysis method in which an initial value is solved using 4-degree terms in taylor expansion of a known differential equation. For example, when the function f (x, y) is dy/dx and the initial values x0 and y0, the four-time taylor expansion of y (x0+ h) at the position x0+ h at the predetermined distance h in the forward direction is y (x0+ h), y0+ hf (x0, y0) + hf (x0+ h/2, y0+ k1/2) + hf (x0+ h/2, y0+ k2/2) + hf (x0+ h, y0+ k 3). Wherein, k1 ═ hf (x0, y0), k2 ═ hf (x0+ h/2, y0+ k1/2), k3 ═ hf (x0+ h/2, y0+ k2/2), k4 ═ hf (x0+ h, y0+ k3), and k ═ k1+2k2+2k3+ k 4)/6. The equipotential line calculating unit 102 repeats this process, and obtains the center point of the traveling path TA at the position TRn ahead of the traveling path TA as shown in the right diagram of fig. 11. The equipotential line computation unit 102 then combines these center points to form a center line CL of the traveling path TA, and outputs the center line CL to the gradient computation unit 103. The gradient calculation unit 103 holds information on the calculated travel path width W and the center line CL of the travel path TA, and outputs the information to the boundary condition setting unit 9.

Returning to fig. 1, the boundary condition setting unit 9 sets a boundary condition based on the travel path width W and the center line CL of the travel path TA acquired from the travel path width calculation unit 10 and the lateral position acquired from the lateral position command unit 8. Fig. 8 and 9 are graphs showing potential values of cross sections along the line VII-VII in fig. 6, where the potential value of the center line CL including the travel path width W and the travel path TA acquired from the travel path width calculation unit 10 is shown by a solid line, and the potential value with respect to the lateral position acquired from the lateral position command unit 8 is shown by a broken line.

That is, the example of the scenario shown in fig. 8 shows a case where the potential value of the left boundary line EL shown by the solid line is + P, the potential value of the right boundary line ER is-P, the center line of the traveling path TA is CL, and the command from the lateral position command unit 8 is at a position offset to the left by X1(m) from the center line CL of the traveling path TA. In this case, as indicated by the broken line, the boundary condition setting unit 9 calculates the potential value P of the left boundary line EL as the boundary condition_1LAnd potential value-P of right boundary line ER_1RThe position at which the potential value P becomes 0 is a position CLa offset leftward by X1 from the center line CL of the travel path TA. Specifically, the gradient k is acquired from the gradient calculation unit 103 of the travel road width calculation unit 10 indicated by the solid line, and P is used_1L＝+P－kX1、P_1RComputing P as a relation of-P-kX 1_1LAnd P_1R. These potential values P_1LAnd P_1RThe boundary condition is output to a boundary condition correction unit 111 of the travel route calculation unit 11, which will be described later.

The example of the scenario shown in fig. 9 shows a case where the potential value of the left boundary line EL indicated by the solid line is + P, the potential value of the right boundary line ER is-P, the center line of the traveling path TA is CL, and the command from the lateral position command unit 8 is at a position offset to the left by X2(m) from the right boundary line ER of the traveling path TA. In this case, as shown by the broken line, the boundary condition setting unit 9Calculating potential value P of left boundary line EL as boundary condition_1LAnd potential value-P of right boundary line ER_1RThe position at which the potential value P becomes 0 is a position CLa offset leftward by X2 from the right boundary line of the travel path TA. Specifically, the gradient k is acquired from the gradient calculation unit 103 of the travel road width calculation unit 10 indicated by the solid line, and P is used_1L＝+P－(2P²/kX2)、P_1RComputing P as a relation of-P_1LAnd P_1R. These potential values P_1LAnd P_1RThe boundary condition is output to a boundary condition correction unit 111 of the travel route calculation unit 11, which will be described later.

Returning to fig. 1, the travel route calculation unit 11 calculates the travel route TR of the host vehicle V based on the integrated travel route boundary information acquired from the travel route boundary integration unit 6 and the boundary condition acquired from the boundary condition setting unit 9, and outputs the calculated travel route TR to the travel route following control unit 12. Fig. 3 is a block diagram showing a specific configuration of the travel route calculation unit 11 in fig. 1, and fig. 12 is a plan view showing the travel route TR calculated by the travel route calculation unit 11. As shown in fig. 3, the travel route calculation unit 11 includes a boundary condition correction unit 111, a potential value calculation unit 112, an equipotential line calculation unit 113, and a gradient calculation unit 114.

The boundary condition correcting unit 111 corrects the potential value of the left boundary line EL of the left boundary information and the potential value of the right boundary line ER of the right boundary information included in the integrated travel path boundary information, based on the integrated travel path boundary information acquired from the travel path boundary integrating unit 6 and the boundary condition acquired from the boundary condition setting unit 9. As shown in fig. 8 and 9, the correction of the potential value is performed in a section where there is a difference between the center line CL of the running path before the correction and the lateral position (the center line CLa of the running path after the correction indicated by the broken line in fig. 8 and 9) acquired from the lateral position command unit 8. That is, the potential value is corrected for a section in which the boundary condition set in the boundary condition setting unit 9 and the potential value initially set in the potential value calculation unit 101 of the traveling road width calculation unit 10, which are obtained by the traveling road width calculation unit 10 and the lateral position command unit 8, are different from each other, and the potential value initially set in the potential value calculation unit 101 is directly used for the other sections.

That is to say that the first and second electrodes,in the case where a certain section of the traveling path TA ahead of the host vehicle V is in the condition shown in fig. 8, the potential value + P of the left boundary line EL is corrected to P for the section_1LThe potential value-P of the right boundary line ER is corrected to-P_1R. Similarly, in the case where the situation shown in fig. 9 is assumed in a certain section of the travel path TA ahead of the host vehicle V, the potential value + P of the left boundary line EL is corrected to P in the section_1LThe potential value-P of the right boundary line ER is set to be-P without correction.

The potential value calculation unit 112 performs the same processing as the potential value calculation unit 101 of the travel path width calculation unit 10 shown in fig. 2, except that the potential value of the left boundary line EL and the potential value of the right boundary line ER of the right boundary information are corrected. That is, the potential value calculation unit 112 corrects the potential value + P for the section corrected by the boundary condition correction unit 111 with respect to the two-dimensional space (x-y plane) of the travel path TA shown in fig. 5_1L、－P_1RAnd, the initial potential values + P and-P of the uncorrected section are set as the potential value of the left side boundary EL and the potential value of the right side boundary ER, respectively, and a potential field is generated in the two-dimensional space (x-y plane) of the travel path TA by an alternative charge method (both referred to as a charge superposition method) to obtain a solution of the laplace equation relating to the electric field. Specifically, a harmonic function defined by the position, direction, and length of a line segment of the polygonal line information of the left-side traveling road boundary information and the right-side traveling road boundary information is used as a basis function, and an approximate solution of linear combination of these functions is used. Here, the midpoint of each line segment of the polygonal line information is selected as an application place of the dirichlet boundary condition, and a linear combination coefficient is obtained by applying an alternative charge method. More specifically, the electric charge (potential value) at all or a part of the two-dimensional space (x-y plane) can be obtained by using the complex potential as an approximate solution of the linear combination of the complex potential and the ground function, which is obtained by converting the traveling road boundary information into the complex information, and using the complex potential as the basis function, by using the complex plane as the two-dimensional space (x-y plane) of the traveling road TA. Further, the complex regularization function as a basis function sets z to a complex variable and is defined by f (z) -In (z 1-z) + In { (z 1-z)/(z 0-z) } (z 0-z)/(z 1-z 0).

The equipotential line calculating unit 113 obtains an equipotential line (equipotential line) by searching for a position to be a reference for equalizing the electric charges (potential values), similarly to the equipotential line calculating unit 102 of the travel path width calculating unit 10 shown in fig. 2. For example, in the example of the traveling path TA shown in fig. 6, since an electric field in which a potential value of +3V or corrected value is applied to the left side boundary line EL and a voltage of-3V or corrected value is applied to the right side boundary line ER is generated as a potential field, the center point of the traveling path TA, which is a position of 0V that is an intermediate value thereof, is searched along the traveling direction of the host vehicle V.

That is, the equipotential line calculating unit 113 presets a position to be a starting point of the center line of the travel path TA on the travel path TA in front of the host vehicle V in the left diagram of fig. 11, and obtains the center point of the true travel path TA by using the newton method. If the true starting point position TR0 of the center line of the travel path TA is obtained by the newton method described above, the equipotential line calculation portion 113 obtains the center point of the travel path TA at a position TR1 located a predetermined distance forward with respect to the traveling direction of the host vehicle V by using the quartic longge-kuta method (RK4), as shown in the right diagram of fig. 11. Then, the equipotential line calculating unit 113 repeats this process to obtain the center point of the traveling path TA at the position TRn ahead of the traveling path TA as shown in the right diagram of fig. 11. Then, as shown in fig. 12, the equipotential line computing unit 113 combines these center points, sets the center line CL of the traveling path TA as the traveling path TR, and outputs the result to the gradient computing unit 114. The gradient calculation unit 114 holds the information of the travel path width W and the travel path TR calculated as described above, and outputs the information to the travel path following control unit 12.

The equipotential line calculating unit 113 determines the center point of the travel path TA at the position TRn ahead of the travel path TA for the section in which the potential value of the left boundary line EL and/or the right boundary line ER is corrected by the boundary condition correcting unit 111. This is because, as shown in fig. 8 and 9, the solution of the laplace equation obtained using the potential values of the corrected left boundary line EL and/or right boundary line ER corresponds to the center line CLa of the corrected travel path.

The travel path following control unit 12 controls a steering device including a steering actuator that performs steering control of the host vehicle V, an acceleration/deceleration drive device including an acceleration actuator (or fuel injection or current of a drive source motor) that performs acceleration or deceleration control of the host vehicle V, and a brake device including a brake actuator that performs brake control of the host vehicle V, with the travel path TR of the host vehicle V acquired from the travel path calculation unit 11 as a target path.

Next, a control procedure of the vehicle travel control device VTC according to the present embodiment will be described with reference to the flowchart of fig. 4. Fig. 4 is a flowchart showing a processing procedure executed by the travel control device VTC of the vehicle shown in fig. 1. As shown in fig. 5, 6, 11, and 12, the configuration of the vehicle travel control device VTC according to the present embodiment described above is described based on a normal road, but in the following control procedure, a scene in which the vehicle V travels on the simple road R shown in fig. 13 will be described in order to facilitate understanding of the operational effects of the present embodiment. The road R shown in fig. 13 indicates one lane on the left side in a country regulated by law for left-side traffic such as japan and the united kingdom. The road R is a wide road R that is wider than 3.5m, which is a normal road width, for example, 5 to 6m in horizontal order, and allows roadside parking.

First, in step S1 of fig. 4, first travel path boundary information in the horizontal plane of the road area on which the host vehicle V is able to travel is detected from the current position information of the host vehicle V acquired by the travel path boundary acquisition unit 1 and the map information defining the road boundary information. At the same time, in step S2, the objects and road conditions around the host vehicle V acquired by the driving road boundary acquisition units 2 to 5 are acquired as the surrounding information, and the second driving road boundary information in the horizontal plane of the road area where the host vehicle V can drive is detected from the surrounding information. The shape of the road other than the obstacle in the vicinity of the vehicle V can be identified from the first traveling road boundary information, and the presence or absence and the type of the obstacle in both the near and far sides around the vehicle V can be identified from the second traveling road boundary information.

In step S3, the travel path boundary integrating unit 6 integrates the first travel path boundary information and the second travel path boundary information acquired by the travel path boundary acquiring units 1 to 5 to generate integrated travel path boundary information. That is, in contrast to the scenario shown in fig. 13, the travel path boundary integrating unit 6 subtracts the existing regions of the obstacles V1, V2, and V3 identified from the position information of the obstacles V1, V2, and V3 acquired by the travel path boundary acquiring units 2 to 5, from the region of the road R identified from the current position information of the host vehicle V acquired by the travel path boundary acquiring unit 1 and the three-dimensional highly accurate map information around the current position information, and calculates the travel path TA on which the host vehicle V can travel.

Further, in step S4, the integrated traveling road boundary integrating unit 6 separates the integrated traveling road boundary information into left traveling road boundary information relating to the left boundary line EL and right traveling road boundary information relating to the right boundary line ER of the traveling road that is the road region on which the cost vehicle V can travel. To explain the scene shown in fig. 13, the traveling road boundary acquisition units 2 to 5 acquire that 3 stationary obstacles (parked vehicles) V1, V2, and V3 are present in the left side portion of the road R, and therefore the left side boundary line EL becomes a line indicated by a broken line, while the right side boundary line ER becomes the same line as the right end RR of the road because no obstacle is present in the right side portion of the road R. The left diagram of fig. 14 shows left-side traveling lane boundary information relating to the left boundary line EL and right-side traveling lane boundary information relating to the right boundary line ER, which are separated.

As described in the section of the background art, when the travel path of the vehicle is generated by the support vector machine based on the set curvature parameter from the left side boundary line EL and the right side boundary line ER shown in the left diagram of fig. 14 and the travel path TA defined by them, as shown in the right diagram of fig. 14, if the section in which there is no parked vehicle as an obstacle is long, the travel path TR becomes a path that fluctuates at that portion, and gives a sense of discomfort to the passenger. In particular, in the wide road R having a horizontal width of 5 to 6m as shown in fig. 13, in the road R allowing curb parking, compared with the road R running along the center of the running path TA, the one running with reference to the right end RR of the road can generate a smooth running path regardless of the presence or absence of curb parking.

Then, in steps S5 to S13, the vehicle travel control device VTC according to the present embodiment uses the solution of the laplace equation to calculate a position offset from the right boundary line ER by X2(m) to the left so as to be the travel path TR of the vehicle V, regardless of whether or not the parked vehicles V1, V2, and V3 are present on the left side road side of the current travel path TA shown in the left diagram of fig. 14.

That is, in step S5, the potential value calculation unit 101 of the travel path width calculation unit 10 generates a potential field in which the left boundary line EL becomes the first potential value (for example, +3V) and the right boundary line ER becomes the second potential value (for example, -3V) in the two-dimensional space (x-y plane) of the travel path TA by using the alternative charge method with respect to the left boundary line EL and the right boundary line ER determined in step S4 shown in the left diagram of fig. 15 and the travel path TA defined by these boundary lines. Next, in step S6, the equipotential line calculating unit 102 searches for a position to be a reference where the charges (potential values) are equal, thereby obtaining an equipotential line (equipotential line). Then, in step S7, the gradient calculation unit 103 obtains the gradient k from the solution of the potential field, calculates the traveling road width W from the traveling road width W shown in fig. 7 as 2P/k, and outputs the traveling road width W to the boundary condition setting unit 9. As shown in the right diagram of fig. 15, the running path width W is calculated at predetermined distance intervals with respect to the running path TA ahead of the host vehicle V. The gradient calculation unit 103 holds information on the calculated travel path width W and the center line CL of the travel path TA, and outputs the information to the boundary condition setting unit 9.

In step S8, the road environment recognition unit 7, the lateral position command unit 8, and the boundary condition setting unit 9 compare the lateral positions. That is, the lateral position command unit 8 detects that the road R on which the host vehicle V is traveling is a lane in which there are many parked vehicles and a country in which the host vehicle V is traveling on the left side as shown in fig. 10 based on the road environment and the country information acquired from the road environment recognition unit 7, and extracts a command in which a position "X2 (for example, 1.5m) from the right end of the travel path" is set as the center line of the travel path TR as the command content of the lateral position. Then, in step S9, as shown in fig. 9, the boundary condition setting unit 9 compares the position of the center line CL of the traveling path TA of the traveling path width W acquired from the traveling path width calculation unit 10 with the position of "X2 (for example, 1.5m) from the right end of the traveling path" extracted by the lateral position command unit 8, and determines whether there is a difference. In this determination, the difference is not necessarily required to be 0, and the presence of a difference of such a degree that the passenger does not feel uncomfortable may be permitted. The determination of the presence or absence of the difference is performed at predetermined distance intervals to obtain the travel path width W shown in the right diagram of fig. 15.

In step S9, the process proceeds to step S10 if it is determined that there is a difference, and proceeds to step S11 if it is determined that there is no difference. In step S10 in which it is determined that there is a difference, the position of the center line CL of the travel path TA of the travel path width W acquired from the travel path width calculation unit 10 is different from the position of "X2 (e.g., 1.5m) from the right end of the travel path" extracted in the lateral position command unit 8 as shown in fig. 9, and therefore, the boundary condition setting unit 9 calculates the potential value P of the left boundary line EL as the boundary condition as shown by the broken line in fig. 9_1LAnd potential value-P of right boundary line ER_1RThe position at which the potential value P becomes 0 is a position CLa offset leftward by X2 from the right boundary line of the travel path TA. Specifically, the gradient k is acquired from the gradient calculation unit 103 of the travel road width calculation unit 10 indicated by the solid line, and P is used_1L＝+P－(2P²/kX2)、P_1RComputing P as a relation of-P_1LAnd P_1R. These potential values P_1LAnd P_1RThe boundary condition is output to the boundary condition correction unit 111 of the travel route calculation unit 11. The boundary condition correcting unit 111 corrects the potential value of the left boundary line EL of the left boundary information and the potential value of the right boundary line ER of the right boundary information acquired from the boundary condition setting unit 9. The left diagram of fig. 16 shows the range of the correction potential values on the traveling path TA in front of the host vehicle V. In this example, as shown in fig. 9, the initial potential value + P is corrected to be larger than the initial potential value + P_1L。

In step S11, the travel route calculation unit 11 sets the corrected potential values (the first potential values for the uncorrected sections) shown in fig. 16 as the left boundary line EL and the right boundary line ER, and generates a potential field in the two-dimensional space (x-y plane) of the travel path TA by using the alternative charge method. Next, in step S12, the equipotential line calculating unit 113 searches for a position (in the present example, a position where the potential value becomes 0V) serving as a reference where the charges (potential values) are equal by using the newton method and the quartic longge-kutta method, and obtains an equipotential line (equipotential line). Since the equipotential lines correspond to the travel route TA of the host vehicle V shown in the right diagram of fig. 16, the equipotential lines are output as the travel route TA to the travel route following control unit 12 in step S13. In step S12, the travel path following control unit 12 automatically controls the steering device, the acceleration/deceleration driving device, and the braking device of the host vehicle along the acquired position information of the travel path TA, thereby executing automatic travel control.

In the above-described embodiment, the potential value of the left side boundary line EL is set to + P (for example, a voltage of +3V), the potential value of the right side boundary line ER is set to-P (for example, a voltage of-3V), a solution of the laplace equation relating to the potential value of the travel path TA is obtained by the alternative charge method, and the position where the potential value becomes 0 is set as the travel path TR, but these + P, -P, and 0 are merely examples, and do not limit the present invention. In the vehicle travel control method and control device according to the present invention, at least the potential value of the left boundary line EL and the potential value of the right boundary line ER are set to different values, a potential field is generated, and a potential value that is a solution of the laplace equation is obtained. Therefore, for example, the potential value of the left side boundary line EL is set to +2P (for example, a voltage of + 6V), the potential value of the right side boundary line ER is set to-P (for example, a voltage of-3V), and a solution of the laplace equation with respect to the potential value of the travel path TA is obtained by the alternative charge method, and the same result is obtained even when the travel path TR is set to a position where the potential value becomes + 3. The solution of the potential field is not limited to the alternative charge method to the electric field, and may be a diffusion equation of heat conduction related to the temperature distribution in a solid body in contact with the heat source or an equation for solving the gravitational potential of the gravitational field as described above.

As described above, according to the vehicle travel control device VTC and the vehicle travel control method of the present embodiment, the lateral position of the preset travel path and the lateral position of the travel path specified by the calculated travel path width are compared, the difference is calculated, the first potential value and/or the second potential value are corrected so that the absolute value of the calculated difference becomes equal to or less than the predetermined value, and the travel path along which the host vehicle travels is generated based on the equipotential lines of the potential field generated by the corrected potential value. This eliminates the uncomfortable feeling of the passenger and realizes smooth automatic travel control.

Further, according to the vehicle travel control apparatus VTC and the vehicle travel control method of the present embodiment, when acquiring left-side travel road boundary information and right-side travel road boundary information, first travel road boundary information within a horizontal plane of a road area on which a host vehicle is able to travel is detected based on current position information of the host vehicle and map information defining the road boundary information, objects and road conditions around the host vehicle are acquired as surrounding information, second travel road boundary information within the horizontal plane of the road area on which the host vehicle is able to travel is detected based on the surrounding information, the first travel road boundary information and the second travel road boundary information are integrated to generate integrated travel road boundary information, and the integrated travel road boundary information is separated into left-side travel road boundary information and right-side travel road boundary information. Therefore, the shape of the road other than the obstacle in the vicinity of the host vehicle V can be identified based on the first traveling path boundary information, and the presence or absence and the type of the obstacle in both the near and far sides around the host vehicle V can be identified based on the second traveling path boundary information. As a result, the left-side road boundary information and the right-side road boundary information including both static information and dynamic information can be acquired with high accuracy.

In addition, according to the vehicle travel control device VTC and the vehicle travel control method of the present embodiment, the lateral position of the travel path set in advance is any one of the lateral center position of the travel path, the position of the first predetermined distance in the left direction from the right end of the travel path, and the position of the second predetermined distance in the right direction from the left end of the travel path. Therefore, when the vehicle is at the lateral center position of the travel path, a travel path with a higher feeling of security for the passenger can be generated. On the other hand, in the case where the position is a first predetermined distance in the left direction from the right end of the traveling road or a second predetermined distance in the right direction from the left end of the traveling road, the traveling route corresponding to the road environment can be generated.

In addition, according to the vehicle travel control device VTC and the vehicle travel control method of the present embodiment, the lateral position of the travel route associated with the road environment information on which the host vehicle travels is stored in advance, the road environment information on which the host vehicle travels is acquired, and the lateral position of the travel route associated with the road environment information is extracted from the stored lateral position. Therefore, the travel route corresponding to the road environment can be generated without increasing the calculation load.

Further, according to the vehicle travel control device VTC and the vehicle travel control method of the present embodiment, the frequencies of the travel directions of the left side travel path boundary information and the right side travel path boundary information are calculated, and the lateral position of the travel route is extracted based on the travel path boundary information having the lower frequency of the left side travel path boundary information and the right side travel path boundary information. Therefore, the passenger's uncomfortable feeling is further eliminated, and smooth automatic travel control can be realized.

Further, according to the vehicle travel control device VTC and the vehicle travel control method of the present embodiment, since the potential value of the potential field uses the approximate solution of the laplace equation, it is possible to suppress generation of a fluctuating travel path, further eliminate the sense of discomfort of the passenger, and realize smooth automatic travel control.

In addition, according to the vehicle travel control device VTC and the vehicle travel control method of the present embodiment, the potential value of the potential field is converted into the left-side travel path boundary information and the right-side travel path boundary information, respectively, and the harmonic function defined by the position, the direction, and the length of the line segment of the respective pieces of the polygonal line information is used as the basis function, and the approximate solution of the linear combination of these is used. Therefore, an approximate solution can be obtained with a low computation load.

In addition, according to the vehicle travel control device VTC and the vehicle travel control method of the present embodiment, the potential value of the potential field is obtained by converting the travel road boundary information into complex information by setting the target horizontal plane as a complex plane, setting the basis function as a complex function, and using the complex potential as an approximate solution of a linear combination of the complex information and the complex information. Therefore, the gradient of the potential value can be obtained with a low computation load.

In addition, according to the vehicle travel control device VTC and the vehicle travel control method of the present embodiment, when z is a complex variable, the basis function is f (z) ═ In (z 1-z) + In { (z 1-z)/(z 0-z) } (z 0-z)/(z 1-z 0). Therefore, since continuous potential values can be obtained by using only the real part, the calculation can be speeded up, and the calculation error can be set to 0 when the left and right roadside boundaries are parallel.

In addition, according to the vehicle travel control device VTC and the vehicle travel control method of the present embodiment, the middle point of each line segment of the polygonal line information is selected as the application location of the dirichlet boundary condition, and the coefficient of the linear combination is obtained by applying the alternative charge method.

Description of the symbols

VTC: vehicle travel control device

1: road boundary acquisition part (high precision map information)

2: traveling road boundary acquisition unit (LRF information)

3: road boundary acquisition part (Radar information)

4: road boundary acquisition part (Camera information)

5: traveling road boundary acquisition part (AVM information)

6: driving road boundary integration part

7: road environment recognition unit

8: lateral position command unit

9: boundary condition setting unit

10: travel road width calculation unit

101: potential value calculation unit

102: equipotential line arithmetic unit

103: gradient calculation unit

11: travel route calculation unit

111: boundary condition correcting unit

112: potential value calculation unit

113: equipotential line arithmetic unit

114: gradient calculation unit

12: travel route following control unit

V: the vehicle

R: road

TA: driving road

TR: travel route

EL: left boundary line

ER: right side boundary line

P: potential value

PF: potential field

W: width of running road