JP4924270B2 - Road information acquisition device, road information acquisition method, and road information acquisition program - Google Patents

Description

  The present invention relates to a road information acquisition apparatus, method, and program for acquiring information about roads.

Conventionally, a technique is known in which a road is a curved road or a straight road by referring to point data registered in advance as map information, calculating a curvature index from the point data, and comparing it with a threshold value. (For example, refer to Patent Document 1).
Japanese Patent Laid-Open No. 9-50597

In the prior art, it has not been possible to accurately acquire information about the curve.
That is, the point data registered in advance as map information usually includes information indicating the position, but the position is often set artificially, and may include an error in the position or an erroneous setting of the point itself. There is. For this reason, even if the information about the curve is acquired based on the point data registered in the map information, the information may be inaccurate information. In particular, when acquiring the start position of a curve and performing vehicle control or guidance based on the start position of the curve, for example, when performing control to change the suspension stiffness from the start position of the curve, the curve If the start position is incorrect, improper control or guidance is performed.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique capable of accurately acquiring information related to a curve.

  In order to achieve the above object, in the present invention, on the road on which the host vehicle is traveling, the start position of the constant curvature curve section where the curvature is constant is acquired, and based on the curvature of the constant curvature curve section Information indicating the clothoid section connected to the constant curvature curve section, and the curvature changes on the road on which the vehicle is traveling based on the information indicating the clothoid section and the start position of the constant curvature curve section. Get the starting curvature change position. That is, in the present invention, the curvature change start position is specified after acquiring information indicating the start position of the constant curvature curve section based on the own vehicle motion information obtained from the motion information of the own vehicle.

  Therefore, compared with a configuration in which the curvature change start position is obtained by referring only to map information that is artificially set in map information and the like and may include inaccurate information, the curvature change start position, that is, the curve The starting position can be obtained. For this reason, control and guidance based on the curvature change start position can be appropriately performed.

  Here, the own vehicle operation information acquisition means only needs to be able to acquire the own vehicle operation information as information for acquiring information about the constant curvature curve section on the road on which the own vehicle is traveling, and the current position of the own vehicle. It is possible to adopt a configuration that acquires information indicating the steering wheel and information indicating the steering operation in the host vehicle. Of course, in order to acquire each information, it is possible to employ various known sensors and cameras. For example, a configuration in which the current position of the host vehicle is specified by the sensor or camera, a signal from GPS or a map A configuration in which a position is acquired based on a trajectory of the host vehicle, a configuration in which information indicating steering operation is acquired by a steering sensor, or the like can be employed.

  The constant curvature curve section information acquisition means only needs to be able to acquire the start position of the constant curvature curve section where the curvature is constant on the road on which the vehicle is traveling. That is, it suffices if a section where the curvature is constant on the road is acquired and the start position of the section can be specified based on the own vehicle operation information. Various configurations can be adopted as the configuration for identifying the curvature of the road. For example, a steering angle of the host vehicle is acquired, a section where the steering angle is constant is acquired, and the section is acquired. It is possible to adopt a configuration in which the starting position of is the starting position of the constant curvature curve section.

  Further, the configuration may be such that the shape of the road on which the host vehicle travels is specified by a sensor or camera mounted on the host vehicle, and the constant curvature curve section and the start position of the constant curvature curve section are acquired from the shape. Further, the curvature may be configured to refer to nodes or shape interpolation points defined in the map information. That is, both the curvature and the start position of the constant curvature curve section may be specified from the information acquired by the sensor or camera, or at least the start position of the constant curvature curve section may be acquired by the sensor or camera. It is good also as a structure using the acquired information.

  The clothoid section information acquisition means acquires information indicating the clothoid section based on the curvature of the constant curvature curve section, and the curvature change start position acquisition means is based on the information indicating the clothoid section and the start position of the constant curvature curve section. It is only necessary that the curvature change start position can be acquired on the road on which the host vehicle is traveling. That is, it is only necessary to acquire a position where the road moves from a straight line (curvature is 0) to a curve (curvature is non-zero).

  In general roads, a relaxation curve is formed between the straight section and the constant curvature curve section to prevent excessive centrifugal force when moving from the straight line to the constant curvature curve section. There is a section.

  The relaxation curve is usually composed of a clothoid curve, and a rule for defining a clothoid curve using a curvature as a parameter can be defined in advance based on a known formula, statistics, or the like. Therefore, if the clothoid curve is specified based on this definition, the shape of the clothoid section can be acquired based on the clothoid curve.

  Therefore, if the clothoid section between the constant curvature curve section and the straight section is specified based on the information indicating the shape of the clothoid section and the start position of the constant curvature curve section, the curvature change start position can be acquired. For example, a shape of a clothoid curve connected to the start position of the constant curvature curve section based on the curvature of the road and having the start position as one end point is obtained, and the other end point of the clothoid curve is set to the curvature change start position. It is possible to adopt the configuration as follows.

  Note that the change in curvature at the curvature change start position is generally very small and appears instantaneously, so it is difficult to obtain the curvature change start position based on the steering angle of the steering, image information acquired by the camera, or the like. It is. However, in the above-mentioned constant curvature curve section, the portion where the curvature is constant is continuous with a certain length, and it is relatively easy to acquire that the curvature is constant while traveling on the road. . Therefore, in the configuration in which the curvature change start position is acquired by detecting the start position of the constant curvature curve section, the curvature change start position can be accurately determined.

  Furthermore, as an example for specifying the curvature change start position based on the above-mentioned clothoid section, a configuration using nodes and shape interpolation points recorded as map information may be adopted. That is, after identifying the shape of the clothoid section based on the curvature, if the shape of the clothoid section is fitted to the node and shape interpolation point existing before the start position of the constant curvature curve section, the clothoid section on the road Can be easily identified. Note that it is sufficient that the points to be fitted include at least a node and a shape interpolation point existing before the start position of the constant curvature curve section. In addition to the node and the shape interpolation point, the point of the constant curvature curve section is included. The start position may be included in the points to be fitted.

  Further, as a configuration example for accurately acquiring the curvature change start position, a configuration may be adopted in which the start position of the constant curvature curve section is specified using the feature of the road on which the vehicle is traveling as a reference position. For example, if image information around the host vehicle is acquired, the positions of the features existing around the host vehicle can be acquired based on the image information and the host vehicle operation information.

  Therefore, if the start position of the constant curvature curve section is specified by the distance from the position of the feature, the start position of the constant curvature curve section can be specified based on the position of the feature. Moreover, since the curvature change start position can be specified based on the information indicating the clothoid section, the curvature change start position can be specified as a relative position with respect to the start position of the constant curvature curve section. Therefore, the curvature change start position can be defined as a relative position with respect to the position of the feature, and the curvature change start position is defined without including the coordinate values defined in the map information that may include inaccurate information. The curvature change start position can be accurately defined.

  The feature extracted based on the image information may be a feature whose relative position does not change with respect to the curvature change start position or the start position of the constant curvature curve section. , Letters, numbers, symbols, road markings such as pedestrian crossings, road fences, stones, and road structures such as highway walls, shoulders, sidewalks, median strips, buildings, signs, signs, traffic lights, etc. It can be adopted as a feature.

  Further, the method of acquiring the start position of the constant curvature curve section based on the operation of the host vehicle and specifying the clothoid section and acquiring the curvature change start position as in the present invention can also be applied as a program or method. . The road information acquisition device, program, and method as described above may be realized as a single road information acquisition device, or may be realized by using parts shared with each part provided in the vehicle. Various embodiments are included. For example, it is possible to provide a navigation device, a method, and a program including the road information acquisition device as described above. Further, some changes may be made as appropriate, such as a part of software and a part of hardware. Furthermore, the invention is also established as a recording medium for a program for controlling the road information acquisition device. Of course, the software recording medium may be a magnetic recording medium, a magneto-optical recording medium, or any recording medium to be developed in the future.

Here, embodiments of the present invention will be described in the following order.
(1) Configuration of navigation device:
(2) Road information acquisition processing:
(2-1) Curvature change start position acquisition processing:
(2-2) Suspension control processing:
(3) Example of operation:
(4) Other embodiments:

(1) Configuration of navigation device:
FIG. 1 is a block diagram showing a configuration of a navigation device 10 including a road information acquisition device according to the present invention. The navigation device 10 includes a control unit 20 including a CPU, RAM, ROM, and the like and a storage medium 30, and the control unit 20 can execute a program stored in the storage medium 30 or the ROM. In the present embodiment, the navigation program 21 can be implemented as one of the programs. The navigation program 21 acquires the curvature change start position on the road on which the host vehicle travels as one of its functions, and maps information As a function of correcting registered information.

  The vehicle according to the present embodiment (a vehicle equipped with the navigation device 10) includes a camera 40, a GPS receiver 41, a vehicle speed sensor 42, a steering sensor 43, and a suspension 44 in order to realize the functions of the navigation program 21. The functions of the navigation program 21 are realized by the cooperation of these units and the control unit 20.

  The camera 40 is attached to the host vehicle so as to include the road on which the host vehicle is traveling, and outputs image data indicating the captured image. The control unit 20 acquires this image data via an interface (not shown). The GPS receiver 41 receives radio waves from GPS satellites and outputs information for calculating the current position of the vehicle via an interface (not shown). The control unit 20 acquires this signal and acquires the current position of the vehicle.

  The vehicle speed sensor 42 outputs a signal corresponding to the rotational speed of the wheels provided in the vehicle. The control unit 20 acquires this signal via an interface (not shown) and acquires the speed of the vehicle. The steering sensor 43 outputs a signal corresponding to the rotation angle of the steering of the vehicle. The control unit 20 acquires this signal via an interface (not shown), and acquires information indicating the steering rotation angle. The vehicle speed sensor 42 and the steering sensor 43 are used to acquire information indicated by the output signals of the sensors and are also used to correct the current position of the vehicle specified from the output signal of the GPS receiver 41. The

  Of course, the configuration for acquiring the current position of the vehicle is not limited to the above-described configuration, and a configuration for acquiring the operation of the vehicle using a gyro sensor or the like may be adopted, or the output of the vehicle speed sensor or the gyro sensor, etc. You may employ | adopt the structure which correct | amends a present position based on a signal and the locus | trajectory of a vehicle. Various other configurations can be adopted for acquiring information indicating the operation of the vehicle, such as a configuration in which the current position of the host vehicle is specified by a sensor or camera, a signal from GPS, or on a map. It is possible to adopt a configuration in which the own vehicle operation information is acquired by vehicle trajectory, vehicle-to-vehicle communication, road-to-vehicle communication, etc.

  The suspension 44 is an anti-vibration mechanism mounted on the host vehicle, and includes a mechanism capable of adjusting the transmission characteristics of an external force acting on the host vehicle from the road surface. The control unit 20 can output a control signal to the suspension 44 via an interface (not shown) to adjust the above-described transfer characteristics. That is, the degree of transmission of external force by the suspension 44 (suspension hardness) can be adjusted.

  The control unit 20 executes a navigation program 21 to perform a vehicle route search or the like based on output information of the GPS reception unit 41, map information described later, and the like, and route guidance and the like via a display unit and a speaker (not shown). I do. At this time, as described above, the navigation program 21 obtains the curvature change start position on the road on which the host vehicle travels, and realizes the function of correcting the information registered as map information. 21a, own vehicle motion information acquisition unit 21b, constant curvature curve section information acquisition unit 21c, clothoid section information acquisition unit 21d, and curvature change start position acquisition unit 21e. Furthermore, a suspension control unit 21f is provided to control the suspension 44 based on the corrected curvature change start position.

  Further, the storage medium 30 stores map information 30a for performing guidance by the navigation program 21. The map information 30a includes node data indicating nodes set on the road on which the vehicle travels, shape interpolation point data for specifying the shape of the road between the nodes, link data indicating the connection between the nodes, the road and its surroundings Is used for specifying the current position of the host vehicle, guiding the destination, and the like. Furthermore, information (curvature change start position information 30b) indicating the corrected curvature change start position is recorded in the storage medium 30. In the present embodiment, the curvature change start position information 30b is expressed by the distance from the paint on the road surface. Note that the curvature change start position information 30b in the present embodiment is not a curvature change start position that can be specified based on nodes or shape interpolation points recorded in the map information 30a, but based on the start position of a constant curvature curve section. It is a curvature change start position specified as described above. Therefore, in this specification, the curvature change start position information 30b is defined as information obtained by correcting the curvature change start position that can be specified based on the map information 30a.

  The image information acquisition unit 21a is a module that acquires image information output by the camera 40, and the acquired image information is transferred to the constant curvature curve section information acquisition unit 21c. The own vehicle operation information acquisition unit 21b acquires various types of information indicating the operation of the own vehicle based on signals output from the GPS reception unit 41, the vehicle speed sensor 42, and the steering sensor 43.

  The constant curvature curve section information acquisition unit 21c is a module that acquires information on a constant curvature curve section where the curvature is constant on the road on which the host vehicle is traveling based on the operation of the host vehicle. Detects a constant curvature curve section based on the output information of the steering sensor 43 and acquires its start position. Moreover, the information which shows the curvature in the said constant curvature curve area is acquired.

  In the present embodiment, the road on which the host vehicle is traveling is determined when the steering angle indicated by the output value of the steering sensor 43 is constant for a predetermined time (or a predetermined distance). It detects that it is a curvature curve section. According to this detection, the position of the host vehicle when the steering angle of the steering wheel is constant can be regarded as the start position of the constant curvature curve section. The start position of the constant curvature curve section is specified based on the distance from the specific reference position.

That is, in the present embodiment, the paint on the road surface is detected based on the image information output from the camera 40, and the travel distance from the vehicle position (reference position) at the time when the paint is photographed is continuously acquired. The travel distance (distance L ₀ ) until reaching the start position of the above-described constant curvature curve section is specified. Then, the start position of the constant curvature curve section is specified by the reference position and the distance L ₀ from the reference position.

  In the present embodiment, the curvature of the constant curvature curve section is acquired based on the nodes and shape interpolation points recorded in the map information 30a. That is, a circle that matches at least three points existing at positions corresponding to the constant curvature curve section is acquired, and the reciprocal of the radius of the circle is used as the curvature of the constant curvature curve section. Here, it is sufficient that the curvature of the constant curvature curve section can be acquired, and the turning radius of the constant curvature curve section is acquired based on the operation of the host vehicle, for example, the steering angle of the steering indicated by the steering sensor 43, and the reciprocal thereof. Various configurations, such as a configuration for acquiring the curvature as a curvature, can be employed.

  The clothoid section information acquisition unit 21d is a module that acquires information indicating a clothoid section connected to the constant curvature curve section based on the curvature of the constant curvature curve section. Based on this, the shape of the clothoid section is specified. In the present embodiment, a clothoid curve is specified based on a statistically defined definition rule of a clothoid coefficient and an approximate expression of a clothoid curve, and a shape of a clothoid section is specified based on the clothoid curve.

なお、ここで、Ｌはクロソイド曲線の開始点からの距離、すなわち、曲線長であり、Ｘ₀及びＹ₀はクロソイド曲線の開始点のＸ座標及びＹ座標である。なお、また、φは次の式（３）で表される。
φ＝α＋２ｋＬ ・・・（３）
ここで、αは開始点の方位であり、ｋはＡ²をクロソイド係数として次の式（４）で表される。
ｋ＝２８／Ａ² ・・・（４） Specifically, a clothoid curve is drawn based on the approximate expression shown in Expressions (1) and (2) (see Japanese Patent Application Laid-Open No. 2005-214839).

Here, L is the distance from the start point of the clothoid curve, that is, the curve length, and X ₀ and Y ₀ are the X coordinate and Y coordinate of the start point of the clothoid curve. In addition, φ is expressed by the following formula (3).
φ = α + 2kL (3)
Here, α is the orientation of the starting point, and k is expressed by the following equation (4) with A ² as a clothoid coefficient.
k = 28 / A ² (4)

In the present embodiment, the clothoid coefficient A ² is associated in advance with the curvature or radius of the constant curvature curve section. For example, the curvature or radius of the constant curvature curve section for a plurality of roads according to the road design map. And the clothoid coefficient A ² of the clothoid curve used in designing each road is obtained. Then, table information or a function indicating a correspondence relationship between the curvature or radius of the constant curvature curve section and the clothoid coefficient A ² may be acquired, and the table information or function may be recorded in the storage medium 30 in advance.

  According to the above approximate expression, the shape of the clothoid curve that spirally extends from the starting point of the clothoid curve can be specified, and a section at a predetermined distance from the starting point can be regarded as the shape of the clothoid section on the road.

  The curvature change start position acquisition unit 21e changes the curvature on the road on which the host vehicle is traveling based on the information indicating the clothoid section identified as described above and the start position of the constant curvature curve section. Get the starting position. In the present embodiment, the clothoid section is identified by performing fitting processing of the shape of the clothoid section, the node, and the shape interpolation point, and the end point of the clothoid section (the end point on the opposite side of the constant curvature curve section) starts to change the curvature. Consider position.

  That is, referring to the map information 30a, a node and a shape interpolation point existing before the start position of the constant curvature curve section (present between the straight section on the road on which the vehicle travels and the start position of the constant curvature curve section). Node and shape interpolation point corresponding to the road) are extracted. Then, the extracted nodes and shape interpolation points are fitted to the clothoid curve indicating the shape of the clothoid section, and the most suitable state is regarded as the curve shape of the clothoid section on the actual road. For fitting, various known techniques can be used.For example, the cumulative value of the shortest distance from a plurality of nodes and shape interpolation points to the clothoid curve is acquired at each position while changing the position of the clothoid curve. It is possible to adopt a process that considers the most suitable state when the cumulative value is the smallest.

When the curvature change start position acquisition unit 21e as to identify the curve shape of the clothoid segment or, on the basis of the distance L ₁ from the end point of the clothoid segment and the start position of the constant curvature curve section to the length of the clothoid curve specific To do. Then, by reducing the distance L ₁ from the distance L ₀ from the reference position described above to the start of the constant curvature curve section, it obtains the distance L ₀ -L ₁ from the reference position, the distance L ₀ from the reference position identifying the curvature change start position by -L _1. That is, the curvature change start position, which is the position at which the road moves from a straight line (curvature is 0) to a curve (curvature is non-zero), is specified by the distance from the reference position. Information indicating the curvature change start position is recorded in the storage medium 30.

  Note that the change in curvature at the curvature change start position is generally very small and appears instantaneously, so it is difficult to obtain the curvature change start position based on the steering angle of the steering, image information acquired by the camera, or the like. It is. However, in the above-mentioned constant curvature curve section, the portion where the curvature is constant is continuous with a certain length, and it is relatively easy to acquire that the curvature is constant while traveling on the road. . Therefore, in the configuration in which the curvature change start position is acquired by detecting the start position of the constant curvature curve section, the curvature change start position can be accurately determined.

The suspension controller 21f outputs a control signal to the suspension 44 to adjust the hardness of the suspension. That is, the image information output by the camera 40 is acquired and the image is analyzed. When the above-described paint is extracted, the travel distance from the position of the own vehicle at the time when the image information is acquired is measured, When the travel distance reaches the distance L ₀ -L ₁ , the suspension 44 is made harder than the straight travel. According to the above configuration, the stiffness of the suspension 44 can be accurately changed when the host vehicle enters the curve.

(2) Road information acquisition processing:
Next, the road information acquisition process which the navigation apparatus 10 implements in the above structure is demonstrated. When the navigation program 21 is being executed by the navigation device 10, each unit included in the navigation program 21 performs the processes shown in FIGS. 2 to 4 at regular time intervals (for example, 100 ms).

  The navigation program 21 executes the process shown in FIG. 2 while the host vehicle is traveling, and acquires information related to the road ahead of the current position of the host vehicle with reference to the map information 30a (step S100). And it is discriminate | determined whether a curve area exists within the predetermined distance (for example, 150m) ahead of the present position of the own vehicle (step S105). Whether or not it is a curve section can be realized by a configuration in which the curvature of the road is acquired from a sequence of nodes and shape interpolation points, and it is determined whether or not the curvature is equal to or greater than a predetermined value. If it is not determined in step S105 that it is a curve section, step S110 and subsequent steps are skipped, and the process shown in FIG.

  When it is determined in step S105 that it is a curve section, the navigation program 21 determines whether or not the curvature change start position has been corrected (step S110). That is, in this embodiment, a corrected flag indicating that the curvature change start position has been corrected or not corrected is set, and the curvature change start position has been corrected when the corrected flag is on. It is determined that the curvature change start position is uncorrected when the flag is off.

  If it is not determined in step S110 that the curvature change start position has been corrected, a curvature change start position acquisition process is performed (step S115), and a process for acquiring the curvature change start position and turning on the corrected flag is performed. I do. On the other hand, when it is determined in step S110 that the curvature change start position has been corrected, a process for controlling the hardness of the suspension 44 is performed based on the corrected curvature change start position (step S120).

(2-1) Curvature change start position acquisition processing:
Next, the curvature change start position acquisition process in step S115 will be described. FIG. 3 is a flowchart showing the curvature change start position acquisition process. In this process, first, the image information acquisition unit 21a acquires image information around the host vehicle based on the output signal of the camera 40 (step). S200). Next, the constant curvature curve section information acquisition unit 21c acquires and analyzes the image information, and determines whether or not paint on the road surface is detected (step S205). That is, image analysis such as edge extraction and pattern matching is performed based on the acquired image information, and it is determined whether or not a predetermined paint (numerical value, symbol, etc.) is detected.

  If it is not determined in step S205 that paint on the road surface has been detected, it is determined whether or not the vehicle has passed the curve section (step S240). That is, referring to the map information 30a, nodes and shape interpolation points are extracted, the curvature of the road is obtained from the arrangement of the nodes and shape interpolation points, and the curvature passes through a section where the curvature is a predetermined value or more. It is determined whether or not a section in which is substantially “0” has been reached. If it is not determined in step S240 that the curve section has been passed, the processes in and after step S200 are repeated. If it is determined in step S240 that the curve section has been passed, the corrected flag is turned off in step S245.

  On the other hand, when it is determined in step S205 that paint on the road surface has been detected, the constant curvature curve section information acquisition unit 21c acquires the position of the paint (step S210). That is, the constant curvature curve section information acquisition unit 21c acquires information indicating the current position of the host vehicle acquired by the host vehicle motion information acquisition unit 21b, and acquires image information including the above-described paint by the camera 40. The position of the own vehicle at the time of the acquisition is acquired. The constant curvature curve section information acquisition unit 21c specifies the travel distance of the host vehicle after passing through the position of the paint based on the information acquired by the host vehicle operation information acquisition unit 21b.

  Next, the host vehicle operation information acquisition unit 21b performs a process of acquiring the steering angle of the steering (step S215). The constant curvature curve section information acquisition unit 21c acquires information indicating the steering angle of the steering, whether the steering angle of the steering is constant, and whether the steering angle is constant has continued for a predetermined period or more. Is determined (step S220). That is, it is determined whether or not the host vehicle is traveling in a constant curvature curve section having a constant curvature.

  If it is not determined in step S220 that the steering angle of the steering wheel is constant and the state in which the steering angle is constant has continued for a predetermined period or longer, the processing after step S240 is executed. When it is determined in step S220 that the steering angle of the steering is constant and the state where the steering angle is constant has continued for a predetermined period or longer, the start position of the constant curvature curve section is acquired (step S225).

That is, the constant curvature curve section information acquisition unit 21c specifies the distance L ₀ that the vehicle has traveled after passing the above-described paint position until the steering angle of the above-described steering becomes constant, and the paint position and The start position of the constant curvature curve section is specified by the distance L ₀ . At this time, the constant curvature curve section information acquisition unit 21c acquires a circle that matches at least three points existing at positions corresponding to the constant curvature curve section, as described above, and the reciprocal of the radius of the circle. Is obtained as the curvature of the constant curvature curve section.

  Next, the clothoid section information acquisition unit 21d acquires the shape of the clothoid section, and the curvature change start position acquisition unit 21e performs a process of acquiring the curvature change start position (step S230). That is, the clothoid section information acquisition unit 21d acquires a clothoid curve corresponding to the curvature of the constant curvature curve section based on the curvature of the constant curvature curve section and the expressions (1) to (4). Then, the curvature change start position acquisition unit 21e fits the clothoid curve, the node and the shape interpolation point existing before the start position of the constant curvature curve section, and acquires the most suitable state as the shape of the clothoid section. .

When the curve shape of the clothoid section is specified as described above, the distance L ₁ from the end point of the clothoid section to the start position of the constant curvature curve section is specified based on the length of the clothoid curve, and from the above-mentioned paint position The distance L ₀ -L ₁ to the curvature change start position is recorded in the storage medium 30 as the curvature change start position information 30b. Then, the corrected flag is turned on (step S235).

(2-2) Suspension control processing:
Next, the suspension control process in step S120 will be described. FIG. 4 is a flowchart showing the suspension control process. In this process, first, the image information acquisition unit 21a acquires image information around the host vehicle based on the output signal of the camera 40 (step S300). Next, the suspension control unit 21f acquires and analyzes the image information, and determines whether paint on the road surface has been detected (step S305). That is, based on the image information acquired in step S300, image analysis such as edge extraction and pattern matching is performed to determine whether or not the above-described paint is detected. If it is not determined in step S305 that the paint has been detected, the processes in and after step S300 are repeated.

On the other hand, when it is determined in step S305 that the paint has been detected, the suspension control unit 21f refers to the curvature change start position information 30b to paint from the road on which the vehicle is traveling to the curvature change start position. A distance L ₀ -L ₁ is acquired (step S310). At this time, the position of the paint is acquired based on the position of the host vehicle at the time when the above-described image information is acquired, and accumulation of the travel distance is started. Then, the suspension control unit 21f performs suspension control at the curvature change start position (step S315). That is, when the cumulative value of the travel distance reaches the distance L ₀ -L ₁ , the suspension control unit 21f outputs a control signal to the suspension 44, and the suspension stiffness is set to a preset normal stiffness. Set it so that it is harder.

(3) Example of operation:
Next, an operation example by the above-described curvature change start position acquisition process and suspension control process will be described. FIG. 5 shows an example of a road on which the host vehicle travels. The extending direction of the road is indicated by a curve and a straight line, and nodes or shape interpolation points recorded in the map information 30a are indicated by black circles. In FIG. 5, the straight line section of the road is shown by a solid line, the clothoid section is shown by a broken line, and the constant curvature curve section is shown by a one-dot chain line. FIG. 5 shows an example in which there is a paint P indicating a regulated speed (40 km / h in the example in the figure) ahead of the host vehicle C.

  When the host vehicle C is traveling on the road shown in FIG. 5, if the host vehicle is traveling on this road for the first time, the curvature change start position is uncorrected in step S110 in the process shown in FIG. It is determined that there is, and the curvature change start position acquisition process shown in step S115 is executed. In the curvature change start position acquisition process, steps S200 and S205 are performed while the host vehicle C is traveling, and when the above-described paint P is photographed by the camera 40, the image information is acquired and the determination in step S205 is performed. The position of the paint P is acquired.

Thereafter, the cumulative value of the travel distance is acquired along with the travel by the host vehicle C, and the steering angle of the steering is detected in steps S215 and S220. When the host vehicle C continues traveling and travels in a constant curvature curve section indicated by a one-dot chain line for a predetermined time or longer, it is determined in step S220 that the state where the steering angle is constant continues for a predetermined time or longer. In step S225, the distance L ₀ from the position of the paint P to the start position of the constant curvature curve section (point S ₀ indicated by a white circle in FIG. 5) is specified based on the cumulative value of the travel distance. Further, the curvature (1 / R (R is the radius of the constant curvature curve section) of the constant curvature curve section) based on the nodes or the shape interpolation points (points P ₀ , P ₁ , P ₂ shown in FIG. 5) of the constant curvature curve section. ) Is identified.

In step S230, a clothoid curve (thick solid line shown in FIG. 5) corresponding to the curvature (1 / R) is specified, and the clothoid curve is identified as a node or a shape interpolation point (point P ₃ , By fitting to P ₄ , P ₅ ), the shape of the clothoid section indicated by the broken line is specified. When the fitting process is performed as described above, the distance L ₁ from the end point S _{1 of the} clothoid segment to the start position S ₀ of the constant curvature curve segment is specified based on the length of the clothoid curve, and the distance L ₀ − L ₁ is recorded in the storage medium 30 as curvature change start position information 30b. In step S235, the corrected flag is set on.

  After the curvature change start position is acquired as described above and the corrected flag is set to ON, when the vehicle C travels on the road shown in FIG. 5 again, in the process shown in FIG. It is determined that the curvature change start position has been corrected, and the suspension control process shown in step S120 is executed. In the suspension control process, steps S300 and S305 are performed while the host vehicle C is traveling, and when the above-described paint P is photographed by the camera 40, the image information is acquired. The position is obtained.

If it is determined that the paint P has been detected, the suspension control unit 21f refers to the curvature change start position information 30b in step S310 to obtain the distance L ₀ -L ₁ from the paint P to the curvature change start position S _1. To do. In addition, the accumulation of the travel distance after passing through the paint P is started. Then, when the cumulative value of the travel distance reaches L ₀ -L ₁ , the suspension control unit 21f outputs a control signal to the suspension 44, and the hardness of the suspension is made harder than the preset normal hardness. Set as follows.

  In the present embodiment, the position of the node or shape interpolation point recorded in the map information 30a is artificially set and may contain an error. If the position of a node or shape interpolation point constituting the clothoid section is inaccurate, the position is erroneous even if the start position (curvature change start position) of the clothoid section is specified from only these nodes or shape interpolation points. Become. Therefore, in this case, the timing for adjusting the stiffness of the suspension is inappropriate.

  However, in the present embodiment, as described above, the curvature change start position is specified based on the position of the paint P acquired by the camera 40, not the node or the shape interpolation point recorded in the map information 30a. . Therefore, the curvature change start position can be accurately specified as compared with the configuration in which the curvature change start position is specified based only on the position of the node or the shape interpolation point recorded in the map information 30a. For this reason, the hardness of the suspension can be adjusted at an appropriate timing.

(4) Other embodiments:
The above embodiment is an example for carrying out the present invention, as long as the start position of the constant curvature curve section is acquired based on the operation of the host vehicle, the clothoid section is specified and the curvature change start position is acquired, Various other embodiments can be employed. For example, the information for specifying the current position of the host vehicle is not limited to the information output from the GPS receiving unit 41, and various known sensors and cameras can be employed. A configuration specified by a camera, a configuration for acquiring a position based on a trajectory of the host vehicle on a map, or the like can be employed.

  The configuration for acquiring information related to the constant curvature curve section is not limited to the steering sensor, and various sensors and cameras can be employed. For example, the configuration may be such that the shape of the road on which the host vehicle travels is specified by a sensor or camera mounted on the host vehicle, and the constant curvature curve section and the start position of the constant curvature curve section are acquired from the shape.

  Furthermore, the configuration for specifying the shape of the clothoid section is not limited to the configuration using the above approximate expression, and may be a configuration using a definition equation of a clothoid curve. In other words, in general roads, a relaxation curve is formed between the straight section and the constant curvature curve section to prevent excessive centrifugal force when moving from the straight line to the constant curvature curve section. Therefore, as long as the clothoid curve as the relaxation curve can be defined, various configurations can be adopted.

  In addition, when acquiring the curvature change start position, it is connected to the start position of the constant curvature curve section based on the curvature of the road and acquires the shape of the clothoid curve with the start position as one end point. A configuration in which the other end point of the curve is set as the curvature change start position may be employed, and various configurations may be employed.

  Further, in the above-described fitting process, it is sufficient that the information to be fitted includes at least nodes and shape interpolation points in the clothoid section, and in addition to these, the start position of the constant curvature curve section is included in the points to be fitted. It may be. Of course, these fitting targets may be only nodes or shape interpolation points.

  Furthermore, in the above-described embodiment, a configuration is adopted in which the starting position of the constant curvature curve section is specified using the feature of the road on which the host vehicle is traveling as a reference position. In the above example, the position of the paint is determined. Of course, the feature is not limited to paint. That is, the feature to be extracted based on the image information may be a feature whose relative position does not change with respect to the curvature change start position or the start position of the constant curvature curve section. , Letters, numbers, symbols, road markings such as pedestrian crossings, road fences, stones, and road structures such as highway walls, shoulders, sidewalks, median strips, buildings, signs, signs, traffic lights, etc. It can be adopted as a feature.

  Furthermore, another configuration may be adopted as a configuration example for acquiring the curvature change start position. For example, the start position of the constant curvature curve section is specified based on the output signal of the GPS receiver 41 or the image information output by the camera 40, and the curvature change start position is determined by the relative positional relationship with respect to the start position of the constant curvature curve section. You may employ | adopt the structure which defines.

  Furthermore, the use target of the curvature change start position is not limited to suspension control. For example, in the case where the host vehicle includes a headlight that can change the light irradiation direction, a headlight control unit that controls the headlight irradiation direction instead of the suspension control unit 21f in the configuration shown in FIG. Constitute. That is, the headlight control unit is configured to output a control signal to the headlight to change the light irradiation direction to a desired direction. Then, when the host vehicle reaches the curvature change start position, the irradiation direction of the headlight is controlled in accordance with the curvature of the curve section ahead. According to this configuration, the irradiation direction of the headlight can be accurately adjusted according to the curvature of the curve section.

  Further, in the host vehicle having a mechanism capable of adjusting the seat position and the degree of support of the passenger's waist and back, a seat control unit that controls the seat position and the degree of support is configured instead of the suspension control unit 21f. That is, the seat control unit is configured to output a control signal to the seat to change the seat position and the support level. Then, when the host vehicle reaches the curvature change start position, the seat position and the support degree are controlled in accordance with the curvature of the curve section in front of the vehicle. According to this configuration, the seat position and the support level can be accurately adjusted according to the curvature of the curve section.

It is a block diagram of the navigation apparatus containing a road information acquisition apparatus. It is a flowchart of a road information acquisition process. It is a flowchart of a curvature change start position acquisition process. It is a flowchart of a suspension control process. It is a figure which shows an operation example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Navigation apparatus, 20 ... Control part, 21 ... Navigation program, 21a ... Image information acquisition part, 21b ... Own vehicle movement information acquisition part, 21c ... Constant curvature curve area information acquisition part, 21d ... clothoid area information acquisition part, 21e ... curvature change start position acquisition unit, 21f ... suspension control unit, 30 ... storage medium, 30a ... map information, 30b ... curvature change start position information, 40 ... camera, 41 ... reception unit, 42 ... vehicle speed sensor, 43 ... steering sensor 44 ... Suspension

Claims (4)

Host vehicle operation information acquisition means for acquiring host vehicle operation information indicating the steering angle of the host vehicle and the current position of the host vehicle;
Image information acquisition means for acquiring image information around the host vehicle;
A section where the steering angle of the steering is constant based on the own vehicle operation information is acquired, and the current state of the own vehicle when a feature existing around the own vehicle is detected based on the image information wherein the position to identify the travel distance of the vehicle to the curvature in the road on which the vehicle is traveling reaches the start position of the constant curvature curve section is constant, the a position of the feature feature Constant curvature curve section information acquisition means for acquiring the start position of the constant curvature curve section by the distance from the position of ,
Information indicating the shape of the clothoid curve connected to the start position of the constant curvature curve section based on the definition rule of the clothoid curve using the curvature of the constant curvature curve section as a parameter and having the start position as one end point Clothoid section information acquisition means to acquire;
Based on the shape of the clothoid section and the start position of the constant curvature curve section, the curvature at which the curvature starts to change on the road on which the own vehicle is traveling at the opposite end of the constant curvature curve section in the clothoid curve the curvature change start position acquiring means for acquiring a change in the starting position,
A road information acquisition device comprising:   The curvature change start position acquisition means acquires a shape interpolation point for reproducing the shape of a node and a road based on map information recorded in a storage medium, and exists before the start position of the constant curvature curve section. Fitting the shape of the clothoid section to the node and the shape interpolation point, the end point on the opposite side to the start position of the constant curvature curve section in the clothoid section as the curvature change start position,
The road information acquisition device according to claim 1.   A host vehicle operation information acquisition step of acquiring host vehicle operation information indicating a steering angle of the host vehicle and a current position of the host vehicle;
  An image information acquisition step of acquiring image information around the host vehicle;
  A section where the steering angle of the steering is constant based on the own vehicle operation information is acquired, and the current state of the own vehicle when a feature existing around the own vehicle is detected based on the image information The travel distance of the host vehicle from the position to the start position of a constant curvature curve section where the curvature is constant on the road on which the host vehicle is traveling is specified, and the position of the feature and the feature A constant curvature curve section information acquisition step of acquiring a start position of the constant curvature curve section by a distance from the position of
  Information indicating the shape of the clothoid curve connected to the start position of the constant curvature curve section based on the definition rule of the clothoid curve using the curvature of the constant curvature curve section as a parameter and having the start position as one end point Clothoid section information acquisition process to be acquired,
  Based on the shape of the clothoid section and the start position of the constant curvature curve section, the curvature at which the curvature starts to change on the road on which the own vehicle is traveling at the opposite end of the constant curvature curve section in the clothoid curve A curvature change start position acquisition step to be acquired as a change start position;
Road information acquisition method including   A host vehicle operation information acquisition function for acquiring host vehicle operation information indicating the steering angle of the host vehicle and the current position of the host vehicle;
  An image information acquisition function for acquiring image information around the host vehicle;
  A section where the steering angle of the steering is constant based on the own vehicle operation information is acquired, and the current state of the own vehicle when a feature existing around the own vehicle is detected based on the image information The travel distance of the host vehicle from the position to the start position of a constant curvature curve section where the curvature is constant on the road on which the host vehicle is traveling is specified, and the position of the feature and the feature A constant curvature curve section information acquisition function for acquiring a start position of the constant curvature curve section by a distance from the position of
  Information indicating the shape of the clothoid curve connected to the start position of the constant curvature curve section based on the definition rule of the clothoid curve using the curvature of the constant curvature curve section as a parameter and having the start position as one end point Clothoid section information acquisition function to acquire,
  Based on the shape of the clothoid section and the start position of the constant curvature curve section, the curvature at which the curvature starts to change on the road on which the own vehicle is traveling at the opposite end of the constant curvature curve section in the clothoid curve Curvature change start position acquisition function acquired as a change start position;
A road information acquisition program that makes a computer realize.

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