JP5316280B2 - Road information learning apparatus, road information learning method, and road information learning program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for determining whether the information is road information which can be referred to in controlling a vehicle. <P>SOLUTION: A road information learning device obtains a measuring value of a sensor mounted on a vehicle, specifies a section stabilized by the measuring value, specifies road information of a road in which a vehicle travels on the basis of the measuring value, and associates to the road information, reliability which is higher when longer the section. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a road information learning device, a road information learning method, and a road information learning program for learning road information.

  Conventionally, by calculating the curvature radius of the road based on the behavior of the vehicle and comparing it with the curvature radius recorded in the database, it is determined whether or not the erroneous control has been performed. A technique for setting so as not to perform corner control referring to map information from the next time is known (for example, Patent Document 1).

JP 2006-218950 A

  In the prior art, the radius of curvature calculated based on the behavior of the vehicle is compared with the radius of curvature recorded in the database, and control is not executed if they do not match. On the other hand, as a result of comparing the curvature radii, in order to control the vehicle when they match, a technology for controlling the vehicle based on the accurate curvature radius is required, and various technologies aiming at accurate vehicle control. Development is underway.

That is, even when the curvature radius calculated based on the behavior of the vehicle matches the curvature radius recorded in the database, the curvature radius recorded in the database may be incorrect. Thus, when the radius of curvature is incorrect, performing control based on the radius of curvature may result in erroneous control. Therefore, in order to perform control based on road information such as a radius of curvature, it is necessary to determine whether or not the road information is accurate.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique for determining whether or not the road information can be referred to during vehicle control.

  In order to achieve the above object, in the present invention, in a configuration in which road information on a road on which the vehicle has traveled is specified based on a measurement value by a sensor mounted on the vehicle and reliability is associated with the road information. The longer the interval where the value is stable, the higher the reliability is associated with. In other words, in a configuration in which a road is measured by a sensor, if the measurement value of the sensor is stably acquired, the accuracy in extracting information regarding the road that is the measurement target from the measurement value of the sensor becomes high. Therefore, it is considered that the reliability of the road information specified from the measured value is higher as the section where the measured value is stable is longer. As a result, it is possible to determine whether or not the road information is information that can be referred to during vehicle control based on the reliability.

  In the configuration in which the road information is specified based on the measurement value of the sensor, the road information is specified by acquiring the measurement value for specifying the road information of the specific road every time the vehicle travels on the specific road, The accuracy of the road information can be improved by traveling the specific road a plurality of times and acquiring a plurality of road information. In this configuration, if it is unclear whether or not the measurement value is accurate, in general, in order to statistically identify road information with high accuracy that can be used for vehicle control, a very large number of measurements are performed. I need it. However, in the present invention, the reliability of the road information specified based on the measured value is specified by the length of the section where the measured value is stable. Therefore, compared with the configuration that statistically identifies the road information from the measured values without considering the length of the section where the measured values are stable, if the measured values are accurate, Whether or not the road information can be used for vehicle control at the stage of acquisition can be specified.

  Here, the measurement value acquisition unit only needs to be able to acquire the measurement value of the sensor, and the sensor includes at least a sensor that can acquire the measurement value for specifying the road information. In other words, the configuration may be such that the section where the measured value is stable and the road information are specified based on one sensor mounted on the vehicle, or the measured value based on a part of the plurality of sensors mounted on the vehicle. It is good also as a structure which identifies the area where is stable, and identifies road information based on some sensors. Of course, in the latter case, the sensor for specifying the section where the measured value is stable and the road information may be matched, may be partially matched, or may be different. The sensor may be any sensor that acquires measurement values according to the operation of the vehicle. In addition to sensors that measure physical quantities such as position, speed, and acceleration, the position, speed, Even a camera or the like for measuring acceleration or the like corresponds to a sensor in the present invention.

  The stable section specifying means only needs to specify that the measurement value is stable and specify the section. That is, the road information specified based on the measured value is considered to be stable when the road information is reliable, and the section may be specified when the measured value is stable. Here, whether or not the measurement value is stable can be determined by the time dependency of the measurement value itself or a value obtained by converting the measurement value. For example, it can be considered that the measurement value is stable when the state in which the amount of change in the measurement value per reference unit is within a predetermined range continues. Here, a unit time or a unit distance can be adopted as the reference unit.

  For example, it is possible to adopt a configuration that is considered stable when a state in which a measurement value acquired within a unit time is within a predetermined range continues for a certain distance or more. In this case, since the change amount of the measured value per unit time is 0, the measured value itself is stable. In addition, it is possible to adopt a configuration that is regarded as stable when a state in which the degree of change of the measurement value acquired within a unit time, the time differentiation of the measurement value, etc. are within a predetermined range continues for a certain distance or more. In this case, the amount of change in the measured value per unit time continues at a constant value that is larger or smaller than 0, and the measured value changes, but the degree of change in the measured value is stable. Become. Furthermore, when the measurement value is stable, it is only necessary to specify a section where the measurement value is stable. For example, a section where the measurement value is maintained within a predetermined range is specified, and the measurement value What is necessary is just to specify the area where the variation | change_quantity of this, the time differentiation of a measured value, etc. are maintained in the predetermined range.

  The road information specifying means only needs to be able to specify the road information of the road on which the vehicle has traveled based on the measurement value. That is, any configuration may be used as long as road information used for vehicle control, such as the shape of a road and the position of a feature on the road, is specified by a sensor. The road information may be a measurement value itself or a value obtained by converting the measurement value.

  In the configuration for specifying the road information based on the measurement value, the reliability specifying unit only needs to be able to associate the reliability for determining the accuracy of the road information with the road information. For this reason, the longer the section in which the measured value is stable, the higher the reliability of the measured value and the higher the reliability of the road information specified from the measured value. The reliability may be an index indicating the possibility that the road information is accurate, and may be expressed in two or more stages or may be expressed as a continuous value. In addition, the length of the section where the measurement value is stable may be specified based on the distance of the section, or the section where the measurement value is stable is specified based on the length of the period during which the vehicle is traveling May be.

  Various configurations can be adopted as the configuration for increasing the reliability according to the length of the section where the measured value is stable, and the configuration for directly adjusting the reliability may be used or the adjustment may be performed indirectly. It may be configured to do so. As the former, for example, it is possible to employ a configuration in which the degree of reliability is increased as the section where the measurement value is stable is longer. As the latter, for example, in the configuration in which the reliability is specified based on the distribution of the measurement values acquired a plurality of times, the longer the interval in which the measurement values are stable, the more reliable the result of the analysis of the distribution considering the measurement values. It is possible to adopt a configuration in which the probability that the degree is determined to be high is increased (for example, the analysis is performed by increasing the weight as the measured value in the stable section is longer).

  Further, the sensor for specifying the stability of the measurement value may be different from the sensor for specifying the road information. For example, in a configuration in which the vehicle is equipped with a first sensor and a second sensor different from the first sensor, a section in which the measurement value of the first sensor is stable is specified, and the second sensor The road information is specified based on the measured value. And it is set as high reliability, so that the area where the measured value of the 1st sensor is stable is long. That is, it is set as the structure which evaluates the stability of a measured value by the 1st sensor different from the 2nd sensor for specifying road information. According to this configuration, it is possible to specify the reliability of the road information based on the measurement value of the first sensor different from the second sensor for measuring the road information. Therefore, the reliability of the road information is specified regardless of the characteristics of the measurement value of the second sensor, such as when the measurement value of the second sensor is not a characteristic suitable for evaluating the stability. The versatility of the present invention can be enhanced.

  Furthermore, this configuration may be applied to the measurement of road information in a curve section. For example, a steering sensor is a first sensor, and a vehicle speed sensor and an acceleration sensor are second sensors. That is, the rudder angle, which is the measurement value of the first sensor, corresponds to the traveling direction of the vehicle, so that if the section where the rudder angle is constant is long, the vehicle travels stably without shaking in the curve section. Can be considered. In this case, the vehicle speed and the acceleration acting on the vehicle in the curve section can be stably measured. Also, when the vehicle travels along the curve section, the trajectory of the vehicle on the curve section is arbitrary, but the vehicle travels along the curve section with a large amount of movement in the traveling direction on the curve section. It is difficult. That is, as the traveling direction of the vehicle is more stable on the curve section, the locus can be regarded as a locus along the shape of the curve section. Therefore, if the curvature of the road is specified based on the vehicle speed and acceleration in the section where the steering angle is constant, the longer the section where the steering angle is constant, the higher the reliability of the curvature. Degree can be defined.

  Further, the reliability of the curvature information may be increased as the road width is narrower. In other words, when a vehicle travels in a curve section, the flexibility of the trajectory of the vehicle on the curve section increases as the width of the road that forms the curve section increases. Accordingly, when the width of the road is wide, there is a large room for selecting a trajectory of the vehicle realized by a certain steering angle and not following the shape of the curve section. In addition, when the road is narrow, there is less room for selecting a trajectory of the vehicle realized by a certain steering angle and not following the shape of the curve section. Therefore, it can be considered that the reliability of the curvature information increases as the width of the road becomes narrower.

  Further, the method of increasing the reliability of road information as the section where the measurement value is stable as in the present invention is longer can be applied as a program or method. In addition, the above-described device, program, and method may be realized as a single device or may be realized by using components shared with each part of the vehicle, and include various aspects. It is a waste. For example, it is possible to provide a navigation device, a method, and a program that include the above devices. 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 apparatus. 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.

It is a block diagram of a navigation device including a road information learning device. It is a figure which shows the frequency distribution of a measured value. (3A) is an example of a curve section, and (3B) and (3C) are examples of a constant curvature section. It is a flowchart of a road information learning process.

Here, embodiments of the present invention will be described in the following order.
(1) Configuration of navigation device:
(2) Road information learning process:
(3) 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 learning device according to the present invention. The navigation apparatus 10 includes a control unit 20 including a CPU, a RAM, a ROM, and the like, and a recording medium 30, and the control unit 20 can execute a program stored in the recording medium 30 and the ROM. In this embodiment, the road information learning program 21 and a vehicle control program (not shown) can be executed as this program. The road information learning program 21 has a function of learning road information of a road on which the vehicle has traveled and associating reliability with the road information. In the present embodiment, the vehicle control program has a function of executing the vehicle control while changing the control amount of the vehicle control according to the reliability of the road information.

  The map information 30a is information used for specifying the position of the vehicle and route guidance of the vehicle, and specifies node data indicating the nodes set on the road on which the vehicle travels and the shape of the road between the nodes. Shape interpolation point data, link data indicating connection between nodes, data indicating features existing on the road and its surroundings, and the like.

  The vehicle in this embodiment (a vehicle on which the navigation device 10 is mounted) includes a GPS receiving unit 41, a vehicle speed sensor 42, a gyro sensor 43, a steering sensor 44, an acceleration sensor 45, a transmission unit 46, and a braking unit 47. . The functions of the road information learning program 21 and the vehicle control program are realized by the cooperation of these units and the control unit 20.

  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 gyro sensor 43 outputs a signal corresponding to the angular velocity acting on the vehicle. The control unit 20 acquires this signal via an interface (not shown) and acquires the traveling direction of the vehicle. The vehicle speed sensor 42 and the gyro sensor 43 are used for correcting the current position of the vehicle specified from the output signal of the GPS receiver 41. Further, the current position of the vehicle is appropriately corrected based on the travel locus of the vehicle.

  The steering sensor 44 outputs a signal indicating the steering angle of the vehicle (the rotation angle from the wheel reference state (0 °)). The control unit 20 acquires this signal via an interface (not shown), and specifies the timing at which the driver operates the steering based on the signal indicating the steering angle of the steering. The acceleration sensor 45 outputs a signal corresponding to the acceleration acting on the vehicle. The control unit 20 acquires this signal via an interface (not shown), and acquires an acceleration having a component in a direction parallel to the lateral direction of the vehicle (lateral acceleration).

  The transmission unit 46 includes a stepped torque converter having a plurality of shift stages such as a total of 6 speeds for forward and a total of 1 speed for reverse, and adjusts the rotational speed with a gear ratio corresponding to each shift stage. Can be transmitted to the wheels of the vehicle. The control unit 20 outputs a control signal for switching the gear position via an interface (not shown), and the transmission unit 46 can acquire the control signal and switch the gear position. In the present embodiment, the gear ratio is configured to become smaller as the gear position becomes high gear, such as the first forward speed to the sixth forward speed.

  The brake unit 47 includes a device that controls the pressure of the wheel cylinder that adjusts the degree of deceleration by the brake mounted on the wheel of the vehicle, and the control unit 20 outputs a control signal to the brake unit 47 to output the wheel cylinder. It is possible to adjust the pressure. Therefore, when the control unit 20 outputs a control signal to the braking unit 47 to increase the pressure of the wheel cylinder, the braking force by the brake is increased and the vehicle is decelerated.

  The control unit 20 learns road information by executing the road information learning program 21 and associates reliability with the road information. For this purpose, the road information learning program 21 includes a measured value acquisition unit 21a, a stable section specifying unit 21b, a road information specifying unit 21c, and a reliability specifying unit 21d. Here, an embodiment will be described in which road information about a curve section made up of information indicating the start position and end position of a curve section, the start position and end position of a constant curvature section, and information indicating the curvature of the constant curvature section is described.

  The measurement value acquisition unit 21a is a module that causes the control unit 20 to realize a function of acquiring a measurement value of a sensor mounted on the vehicle. In the present embodiment, the control unit 20 acquires measurement values from the GPS reception unit 41, the vehicle speed sensor 42, the gyro sensor 43, the steering sensor 44, and the acceleration sensor 45 by the processing of the measurement value acquisition unit 21a. In the present embodiment, the sensors mounted on the vehicle include a first sensor that acquires a measurement value that is a stability evaluation target and a second sensor that acquires a measurement value for specifying road information. The steering sensor 44 is a first sensor, and the vehicle speed sensor 42 and the acceleration sensor 45 are second sensors.

  When the measurement value of each sensor is acquired, the control unit 20 records each measurement value on the recording medium 30 as measurement value information 30b. That is, the steering angle θr, which is a measurement value of the steering sensor 44, the vehicle speed Vr, which is a measurement value of the vehicle speed sensor 42, and the lateral acceleration Yr, which is a measurement value of the acceleration sensor 45, are obtained by the GPS receiver 41, the vehicle speed sensor 42, and the gyro sensor 43. The measured value information 30b is recorded in the recording medium 30 in association with the position r of the vehicle specified by. Note that the subscript r of the steering angle θr, the vehicle speed Vr, and the lateral acceleration Yr indicates that each measured value depends on the position r.

  The stable section specifying unit 21b is a module that causes the control unit 20 to realize a function of specifying a section in which a measurement value is stable. In the present embodiment, a configuration is adopted in which a state in which the amount of change in measured value per unit time is within a predetermined range is regarded as a state in which the measured value itself is stable. More specifically, a configuration is adopted in which the measured value is considered stable when the state in which the measured value acquired within the unit time is 0 continues for a certain distance or more. Therefore, the control unit 20 acquires the steering angle θr with reference to the measurement value information 30b, and the steering angle θr is a specific angle and the error per unit time from the specific angle is within a predetermined range. In this case, the steering angle θr is considered to be constant. Then, a start position and an end position in a state where the steering angle θr is constant are identified and regarded as a section where the steering angle θr is constant. A section where the steering angle θr is constant is regarded as a constant curvature section. In determining whether the steering angle θr is constant, it may be configured to determine whether an error per unit distance from a specific angle is within a predetermined range.

  The road information specifying unit 21c is a module that causes the control unit 20 to realize the function of specifying the road information of the road on which the vehicle has traveled based on the measured value. The reliability specifying unit 21d is a section in which the measured value is stable This is a module that causes the control unit 20 to realize a function of associating road information with higher reliability as the length increases. The specification of the road information and the specification of the reliability are configured based on the frequency distribution of the measurement values, and the control unit 20 converts the measurement values into the measurement values every time the vehicle travels the curve section by the processing of the road information specification unit 21c. The road information is specified based on the distribution information 30c indicating the frequency distribution of the road information by the processing of the reliability specifying unit 21d and recorded in the recording medium 30.

That is, the control unit 20 acquires the steering angle θr, the vehicle speed Vr, and the lateral acceleration Yr with reference to the measurement value information 30b, and specifies the start position and the end position for a constant curvature section where the steering angle θr is constant. Then, the vehicle speed Vr and the lateral acceleration Yr in the constant curvature section are acquired, and the curvature (Y / V ² ) is acquired based on the average vehicle speed V and the average lateral acceleration Y that are average values thereof. Further, the position at which the steering angle θr of the vehicle becomes an angle other than 0 ° before reaching the constant curvature section is set as the start position of the curve section, and the steering angle θr of the vehicle is set to 0 ° after passing through the constant curvature section. This position is the end position of the curve section.

  The road information including the start position and end position of the curve section specified as described above, the start position and end position of the constant curvature section, and the curvature is specified every time the vehicle travels in the curve section. May vary from run to run. Therefore, in this embodiment, these values are specified by statistical processing.

  FIG. 2 is an explanatory diagram for explaining the statistical processing by taking curvature as an example. FIG. 2 shows a frequency distribution of curvature with the vertical axis representing the frequency and the horizontal axis representing the curvature. The frequency distribution is expressed in units of a predetermined interval and the number of times the curvature within each interval is measured. is there. In the present embodiment, the control unit 20 employs a configuration in which the measurement value having the highest measurement probability, that is, the curvature constituting the maximum frequency in the frequency distribution is specified as the curvature of a constant curvature section.

FIG. 3A is a diagram illustrating an example of a curve section including a constant curvature section. In FIG. 3A, clothoid sections provided before and after the constant curvature section are indicated by arrows L ₀ and L ₁ indicated by broken lines, and the constant curvature section is indicated by arrow L ₂ indicated by a one-dot chain line. In FIG. 3A, the start position and end position of the curve section are shown as K ₁ and K ₂ , and the start position and end position of the constant curvature section are shown as R ₁ and R ₂ . Further, in FIG. 3A, examples of trajectories that the vehicle can travel in and around the constant curvature section are indicated by solid arrows, and periods in which the steering angle of the vehicle is constant in each trajectory are indicated by thick solid lines. . That is, FIG. 3A shows a trajectory in which the rudder angle is constant over the entire constant curvature section and a trajectory in which the rudder angle is constant in a small part of the constant curvature section, and the rudder angle is constant in the former. A trajectory of a period of time is shown as a trajectory T ₁ , and a trajectory of a period where the steering angle is constant in the latter is shown as a trajectory T ₂ .

Comparing the trajectory T ₁ and the trajectory T ₂ , the shape of the trajectory T ₁ whose steering angle is constant over the entire section of the constant curvature section almost coincides with the road shape of the constant curvature section as shown in FIG. 3A. but the shape of the periods is the steering angle is constant is short trajectory T ₂ are different from the road shape of the fixed curvature segment. Therefore, the curvature specified from the shape of the trajectory T _{1 and} the curvature of the constant curvature section substantially match, but the curvature specified from the shape of the trajectory T _{2 and} the curvature of the constant curvature section do not always match. In addition, the start position and end position of the trajectory T _{1 and} the start position and end position of the constant curvature section substantially coincide with each other, but the start position and end position of the trajectory T _{2 and} the start position of the constant curvature section and The end positions do not match.

  Furthermore, it is difficult to travel for a long period of time at a constant rudder angle (steering angle ≠ 0 °) in the curve section before and after the constant curvature section. Therefore, when the vehicle can travel for a long time at a constant steering angle (steering angle ≠ 0 °) in the curve section, the section is highly likely to be a constant curvature section. Further, since the rudder angle corresponds to the traveling direction of the vehicle, if the section where the rudder angle is constant is long, the vehicle is traveling stably without shaking in the constant curvature section. The vehicle speed and acceleration acting on the vehicle can be measured stably. Therefore, the reliability of the road information is set higher as the section where the measured value is stable is longer.

  The reliability specifying unit 21d is a module that causes the control unit 20 to realize a function of associating the reliability with road information. That is, the control unit 20 adjusts the frequency distribution indicated by the distribution information 30c for each measurement value by the process of the reliability specifying unit 21d and the correspondence of the reliability to the road information specified by the process of the road information specifying unit 21c. Perform. Specifically, in the curvature frequency distribution as shown in FIG. 2, the control unit 20 sets the frequency to be increased to 0.9, 1.0, and the like to incorporate the measurement value corresponding to one measurement into the frequency distribution. Set to any of 1.2. That is, in this embodiment, the control unit 20 regards the length of the constant curvature section specified from the start position and the end position of the constant curvature section described above as the length of the section where the measurement value is stable. The control unit 20 increases the frequency to be increased by 1.0 when the length of the constant curvature section is within the reference range, 0.9 when the length of the constant curvature section is shorter than the reference range, and by the constant curvature section. If the length is longer than the reference range, it is set to 1.2.

  In the present embodiment, as described above, the length of the constant curvature section is classified into a three-stage range and the frequency to be increased is determined, and further, the three-stage range is determined by the curvature radius of the constant curvature section. It is configured to vary. For this reason, in the present embodiment, frequency information 30 d indicating the frequency to be increased is recorded in advance on the recording medium 30.

分布情報３０ｃは、以上のような度数を増加させることによって構成された度数分布を示す情報であり、以上のような度数の増加により分布情報３０ｃが示す度数分布においては測定値が安定している区間の長さが長いほどその測定値が度数分布の度数増加に与える影響が大きくなるように設定されていることになる。 Table 1 is a table showing an example of the frequency information 30d. In Table 1, the three-step range indicating the length of the constant curvature section is made to correspond to the increasing frequency described above, and for each radius of curvature. The range of the three stages is shown. For example, when the radius of curvature of the constant curvature section (the reciprocal of the above-mentioned curvature) is 10 to 50 m, if the length of the constant curvature section is 0 to 20 m, the degree of increase in which the stability of the measured value is considered low. Is set to 0.9. Further, if the radius of curvature of the constant curvature section is 10 to 50 m and the length of the constant curvature section is 20 to 30 m, it is assumed that the stability of the measured value cannot be determined as low or high, and the frequency that increases is set to 1.0. Then, if the radius of curvature of the constant curvature section is 10 to 50 m and the length of the constant curvature section is longer than 30 m, the degree of increase is set to 1.2, assuming that the stability of the measured value is high.

The distribution information 30c is information indicating the frequency distribution configured by increasing the frequency as described above, and the measurement value is stable in the frequency distribution indicated by the distribution information 30c due to the increase in frequency as described above. The longer the section length, the greater the influence of the measured value on the frequency increase of the frequency distribution.

  When the frequency distribution is adjusted as described above, the control unit 20 specifies the road information by the process of the road information specifying unit 21c, specifies the reliability of the road information by the process of the reliability specifying unit 21d, and the road. Associate with information. That is, the control unit 20 specifies the curvature constituting the maximum frequency from the frequency distribution indicated by the distribution information 30c by the processing of the road information specifying unit 21c, and regards it as the curvature of the constant curvature section. In the present embodiment, the value of curvature is regarded as the median value in the horizontal axis direction of each bar graph in the bar graph constituting the frequency distribution. For example, in FIG. 2, the bar graph shown with hatching is the maximum frequency, and the curvature is the median value D of the bar graph with hatching. When the curvature is specified, the control unit 20 records the road information indicating the curvature, the start position and end position of the curve section, and the start position and end position of the constant curvature section on the recording medium 30 as road information 30e.

  Furthermore, the control unit 20 specifies the reliability of the curvature based on the frequency distribution indicated by the distribution information 30c by the process of the reliability specifying unit 21d. In the present embodiment, the control unit 20 is reliable when the sum of the frequencies in the frequency distribution indicated by the distribution information 30c is greater than or equal to a predetermined threshold S and the curvature constituting the maximum frequency is measured with a predetermined probability P or greater. Considered high degree. Moreover, the control part 20 considers that reliability is low when this condition is not satisfy | filled. And the information which shows reliability is matched with the above-mentioned road information 30e.

In specifying the reliability, in this embodiment, when configuring the frequency distribution,
The amount of increase in the frequency of curvature measured as described above is not limited to 1, and the frequency is set so that the amount of increase increases as the length of the section in which the measured value is stable increases. Further, when specifying the reliability of curvature, it is determined whether or not the sum of the frequencies is equal to or greater than a predetermined threshold S, and whether or not the measurement probability of the curvature constituting the maximum frequency is equal to or greater than the probability P. In the frequency distribution, the greater the frequency of a specific curvature value, the higher the probability that the reliability is considered higher. Therefore, according to this embodiment, it is possible to increase the probability that the reliability is considered higher as the length of the section in which the measurement value is stable is longer. For this reason, when measured values that are stable over a long section are measured, road information can be identified with a small number of measurements compared to the case where a stable section is measured with a short measured value. Is possible.

  In the present embodiment, the distribution information 30c indicating the frequency distribution is also recorded on the recording medium 30 for the start position and end position of the curve section and the start position and end position of the constant curvature section, which corresponds to the maximum frequency in the frequency distribution. The value to be regarded is a value indicating these positions. Further, the reliability is associated with the start position and the end position of the constant curvature section. In other words, in the present embodiment, with respect to the start position and end position of the curve section, a value indicating the position is specified by configuring the frequency distribution without adjusting the frequency based on the length of the constant curvature section. For the start position and the end position of the constant curvature section, the frequency is adjusted based on the length of the constant curvature section, and the value indicating the position is specified by configuring the frequency distribution. The longer the constant curvature section, the higher the reliability of the start position and end position of the constant curvature section, and the value corresponding to the maximum frequency in the frequency distribution for each of the start position and end position of the constant curvature section Are assumed to be the start and end positions of a constant curvature section.

  The control unit 20 controls the vehicle with reference to the road information 30e specified as described above. That is, the control unit 20 decelerates the vehicle speed so that the vehicle speed becomes the target vehicle speed in the section from the start position of the curve section to the start position of the constant curvature section by the processing of the vehicle control program. At this time, the control amount is set to increase as the curvature reliability increases.

  For example, while the control unit 20 outputs control signals to the transmission unit 46 and the braking unit 47 and travels from the start position of the curve section to the start position of the constant curvature section, it controls the transmission ratio and the pressure of the wheel cylinder. A configuration is assumed in which a process for generating a braking force for decelerating the current vehicle speed to the target vehicle speed is performed. In this configuration, when the reliability of the curvature of the constant curvature section is high, the vehicle speed for driving the constant curvature section at a constant vehicle speed is set as the target vehicle speed, and when the reliability of the curvature of the constant curvature section is low, the constant curvature section The vehicle speed higher than the vehicle speed for traveling at a constant vehicle speed is set as the target vehicle speed. With this configuration, the vehicle can be controlled so that the braking force acting on the vehicle is large when the reliability of the curvature of the constant curvature section is high, and the braking force acting on the vehicle is small when the reliability is low. it can.

  As described above, according to the present embodiment, it is possible to perform vehicle control by varying the control amount (braking force acting on the vehicle) according to the reliability. In vehicle control, the larger the control amount, the greater the influence of malfunction, but in this embodiment, the reliability is associated with the road information 30e referred to when performing vehicle control, and the higher the reliability, the higher the reliability. Since the road information 30e is accurate, it can be determined that the higher the reliability is, the greater the amount of control that can be referred to. Therefore, according to the present embodiment, it is possible to determine whether or not the road information 30e is information that can be referred to during vehicle control based on the reliability. Further, since the frequency is adjusted based on the frequency information 30d, the reliability of the road information 30e is specified based on a relatively small number of measurement values before acquiring a statistically sufficient number of measurement values. Can do. Accordingly, the reliability of the road information 30e based on a small number of measurement values compared to a configuration in which the road information 30e is statistically specified from the measurement values without considering the length of the section where the measurement values are stable. It is possible to determine whether or not the road information 30e can be referred to during vehicle control based on a relatively small number of measurement values.

  Further, in the present embodiment, the stability of the measurement value is evaluated by a first sensor (steering sensor 44) different from the second sensor (vehicle speed sensor 42 and acceleration sensor 45) for specifying the road information 30e. It has become. According to this configuration, the reliability of the road information 30e can be specified based on the measurement value of the first sensor different from the second sensor for measuring the road information 30e. Therefore, the reliability of the road information 30e is specified regardless of the characteristics of the measurement value of the second sensor, such as when the measurement value of the second sensor is not a characteristic suitable for evaluating the stability. This can improve the versatility of the present invention.

  In the present embodiment, the road information 30e and the map information 30a are separate information, but the map information 30a may be updated based on the road information 30e. That is, when information with high reliability exists in the information indicated by the road information 30e, the map information 30a is updated with the information. According to this configuration, it is possible to accurately perform control such as route guidance based on the map information 30a. Further, when the road information 30e and the map information 30a are configured as separate information, and the road information 30e has high reliability, vehicle control is performed based on the road information 30e, and the road information 30e has low reliability. May adopt a configuration in which vehicle control is performed based on the map information 30a.

(2) Road information learning process:
Next, road information learning processing performed by the navigation device 10 in the above configuration will be described based on the flowchart shown in FIG. 4 and the specific example shown in FIG. 3A. The control unit 20 executes the road information learning process shown in FIG. 4 at predetermined intervals (for example, 100 ms) while the vehicle is traveling. In this process, the control unit 20 acquires the current position of the vehicle and the measured value of the sensor by the process of the measured value acquiring unit 21a (step S100). That is, the control unit 20 acquires the current position of the vehicle based on output signals from the GPS receiving unit 41, the vehicle speed sensor 42, and the gyro sensor 43, and acquires measured values of the steering sensor 44, the acceleration sensor 45, and the vehicle speed sensor 42. To do.

  Next, the control unit 20 determines whether or not the vehicle is turning by the process of the measurement value acquisition unit 21a (step S105). That is, it is determined whether the steering angle θr is a value other than 0 °. When it is determined in step S105 that the vehicle is turning, the control unit 20 determines whether or not a flag F indicating whether the vehicle is turning is set to 0 (step S110). If it is determined in step S110 that the flag F is set to 0, the flag F is set to 1 indicating that the vehicle is turning (step S115), and the process shown in FIG. Therefore, the flag F becomes 1 after the next time.

  If it is not determined in step S110 that the flag F is set to 0, that is, if it is determined that the flag F is set to 1, the control unit 20 performs sensor processing by the measurement value acquisition unit 21a. (The steering angle θr, the vehicle speed Vr, and the lateral acceleration Yr) are recorded in the recording medium 30 as measured value information 30b. That is, when the vehicle is turning, S120 is executed according to the determinations in steps S105 and S110, and recording of the measurement value information 30b is continued.

  On the other hand, when it is not determined in step S105 that the vehicle is turning, the control unit 20 determines whether or not the flag F is set to 1 by the process of the measurement value acquisition unit 21a (step S125). If it is not determined that F is set to 1, the process after step S130 is skipped and the process ends. That is, if it is not determined in step S125 that the flag F is set to 1, the vehicle is not currently turning and the sensor measurement value is not recorded, so the road information is not learned. The process ends.

On the other hand, when it is determined in step S125 that the flag F is set to 1, the control unit 20 initializes the flag F to 0 (step S130). Then, the control unit 20 uses the processing of the road information identifying unit 21c, it refers to the measurement value information 30b, the curve section in which the vehicle has passed the start of the start position K ₁ and the end position K ₂ of the curve section fixed curvature segment The position R ₁ and the end position R ₂ and the curvature are specified (step S135).

Furthermore, the control part 20 specifies the length of a fixed curvature area by the process of the stable area specification part 21b (step S140). That is, the control unit 20 specifies the start position R ₁ and the end position R ₂ of the constant curvature section based on the steering angle θr, and specifies the length of the constant curvature section. Here, the length of the constant curvature section can be specified by various methods. For example, assuming a circle having the same radius as the curvature radius of the constant curvature section and having a start position R ₁ and an end position R ₂ of the constant curvature section on the outer periphery, the start position R ₁ and the end of the constant curvature section are assumed. Assuming an arc whose position R ₂ is a chord, the length of the arc can be set to the length of a certain curvature section. The length of the constant curvature section can be specified by various other methods. For example, the distance may be specified based on the vehicle speed and the travel period specified from the vehicle speed sensor 42 at the start position R ₁ and the end position R ₂ of the constant curvature section. In addition, the number of pulses output from the vehicle speed sensor 42 at the start position R ₁ and the end position R ₂ of the constant curvature section is specified, and the distance is specified by multiplying the travel distance and the number of pulses for each pulse output interval. Also good.

  Next, the control unit 20 specifies the frequency based on the frequency information by the process of the reliability specifying unit 21d (step S145). That is, the control unit 20 specifies the radius of curvature from the curvature of the constant curvature section, and specifies a range in which the length of the constant curvature section is included in a three-stage range corresponding to the curvature radius. Then, the frequency corresponding to the length of the constant curvature section is specified.

Next, the control unit 20 specifies the curvature and the start position and the end position of the constant curvature section based on the frequency distribution by the processing of the road information specifying unit 21c (step S150). That is, the control unit 20 updates the distribution information 30c by increasing the frequency specified in step S140 for the curvature value specified in step S135. Similarly, the control unit 20 updates the distribution information 30c by increasing the frequency specified in step S140 for the start position and end position of the constant curvature section specified in step S135. Then, the curvature having the maximum frequency in the updated distribution information 30c, the start position and the end position of the constant curvature section are the curvature of the constant curvature section, and the start position R ₁ and the end position R ₂ of the constant curvature section, respectively. It is with regards to the recording medium 30 as the road information 30e with the starting position K ₁ and the end position K ₂ of the curve section.

Next, the control unit 20 specifies the curvature and the reliability of the start position R ₁ and the end position R ₂ of the constant curvature section by the process of the reliability specifying unit 21d (step S155). That is, in the frequency distribution indicated by the updated distribution information 30c described above, the reliability is high when the sum of the frequencies is equal to or greater than a predetermined threshold S and the curvature constituting the maximum frequency is measured with a predetermined probability P or higher. Consider it expensive. Moreover, the control part 20 considers that reliability is low when this condition is not satisfy | filled. Similarly, with respect to the start position R ₁ and the end position R ₂ of the constant curvature section, the start position and the end position constituting the threshold and the maximum frequency set for the sum of the frequencies in the frequency distribution indicated by the updated distribution information 30c. The reliability is specified based on a predetermined probability set for the measurement probability. And the information which shows reliability is matched with the above-mentioned road information 30e.

(3) Other embodiments:
The above embodiment is an example for carrying out the present invention, and various other embodiments can be adopted as long as the section where the measurement value is stable is longer and the reliability of the road information is increased. . For example, the sensor for acquiring the measurement value may be at least a sensor for specifying the road information, and various sensors other than the above-described embodiment can be assumed. In other words, the configuration may be such that the section where the measured value is stable and the road information are specified based on one sensor mounted on the vehicle, or the measured value based on a part of the plurality of sensors mounted on the vehicle. It is good also as a structure which identifies the area where is stable, and identifies road information based on some sensors. Of course, in the latter case, the sensor for identifying the section where the measured value is stable and the road information may be coincident, may be partially coincident, and the measured value is stable as in the above-described embodiment. The sensor which specifies the section and the road information may be different. The sensor may be any sensor that acquires measurement values according to the operation of the vehicle. In addition to sensors that measure physical quantities such as position, speed, and acceleration, the position, speed, Even a camera or the like for measuring acceleration or the like corresponds to a sensor in the present invention.

  When determining the stability of a measured value, if the road information specified based on the measured value is reliable, the measured value is considered stable, and if the measured value is stable, It suffices if the section can be specified. As a configuration for this, in addition to the configuration for determining whether or not the measurement value itself is temporally stable as in the above-described embodiment, the determination is made based on the time dependency of the value obtained by converting the measurement value. Alternatively, the stability of the measurement value may be determined using a distance other than the unit time as a reference unit. That is, the measured value can be regarded as stable when the amount of change in the measured value per reference unit (unit time or unit distance) is within a predetermined range for a certain distance (or a certain period). . More specifically, when the degree of change in the measured value acquired within a unit time (or unit distance) or the time derivative (or distance derivative) of the measured value is within a predetermined range continues for a certain distance or more. It is possible to adopt a configuration that is considered to be stable. This state is a state in which the amount of change in the measured value per reference unit continues at a constant value that is larger or smaller than 0, and the measured value changes, but the degree of change in the measured value is stable. It will be. Therefore, if a section in which the degree of change in the measured value, the time derivative of the measured value, etc. are maintained within a predetermined range is specified, the section in which the measured value is stable can be specified.

  The road information may be information on the road on which the vehicle specified based on the measurement value has traveled. Therefore, in addition to the start position, end position, and curvature of the constant curvature section as described above, various information such as the shape of other roads that can be specified by the sensor and the position of features on the road can be used as road information. . For example, if it is assumed that a section existing before and after a certain curvature section in a curve section is a clothoid section, the measured value of the sensor indicates that the clothoid section is running and the measured value is stable. It can be considered that the longer the start position and the end position of the clothoid section and the shape of the clothoid section are identified with higher reliability.

  More specifically, when the vehicle is driven at a constant vehicle speed and the steering angle of the steering is rotated at a constant angular velocity, the locus of the vehicle becomes a clothoid curve. Therefore, when the measurement value of the vehicle speed sensor 42 indicates that the vehicle speed is constant and the measurement value of the steering sensor 44 indicates that the amount of change in the steering angle per unit time is constant, the section is defined as clothoid. Consider a section. The position at which the change amount of the steering angle per unit time has changed from 0 to a constant value other than 0 is set as the start position of the clothoid section, and the change amount of the steering angle per unit time is changed from a constant value other than 0 to 0. The position changed to is regarded as the end position of the clothoid segment. Further, the shape of the clothoid section is specified from the amount of change in the steering angle between the start position and end position of the clothoid section. And it is considered that the reliability of the road information regarding a clothoid section is so high that the length of the section regarded as the clothoid section is long. According to this configuration, it is possible to specify the road information related to the clothoid section based on the measured value and to specify the reliability of the road information.

  Of course, the above configuration is merely an example, and a section where the product of the radius of curvature and the distance from the start position of the clothoid section is constant (the error per unit time is within a predetermined range) is regarded as a clothoid section, and the product is constant. The longer the section is, the higher the reliability may be. In addition to road information related to clothoid sections and constant curvature sections, the present invention can be applied to all information that can specify road information using sensors. For example, a configuration may be adopted in which a section where the steering angle is 0 ° is regarded as a straight section, and the reliability is considered to be higher as the section where the steering angle is 0 ° is longer. Of course, the measurement value for specifying whether or not it is a straight section is not limited to the steering angle. For example, the straight section may be specified based on the curvature being 0 and the lateral acceleration being 0.

  Furthermore, the reliability may be an index indicating the possibility that the road information is accurate, and may be expressed in multiple stages of three or more in addition to the configuration in which the level of reliability is expressed in two stages. It may be expressed by the value to be. Further, the length of the section in which the measured value is stable may be specified based on the length of the period in which the vehicle is traveling in the section in which the measured value is stable.

  Further, the reliability may be adjusted indirectly by adjusting the frequency as described above, or the value indicating the reliability itself directly according to the length of the section where the measurement value is stable. The structure to adjust may be sufficient.

Further, the reliability of the curvature information may be increased as the road width is narrower. In other words, when a vehicle travels in a curve section, the flexibility of the trajectory of the vehicle on the curve section increases as the width of the road that forms the curve section increases. In particular, the distance that can be traveled while maintaining a curvature different from the curvature of the constant curvature section in the constant curvature section included in the curve section becomes longer as the road width of the curve section is wider. 3B and 3C are diagrams schematically showing the constant curvature section, and the road width W ₁ of the constant curvature section shown in FIG. 3B is wider than the road width W ₂ of the constant curvature section shown in FIG. 3C. Trajectories T ₃ and T ₄ indicated by thick arrows in FIG. 3B and trajectories T ₅ and T ₆ indicated by thick arrows in FIG. 3C are constant curvature trajectories, and the curvatures of trajectories T ₃ and T ₅ are equal. The curvatures of the trajectory T ₄ and the trajectory T ₆ are equal.

As shown in FIGS. 3B and 4C, either of the trajectories T ₃ and T ₄ can be selected in the constant curvature section of the road width W ₁ , but the trajectory T in the constant curvature section of the road width W _{2. 5} is the trajectory T ₆ of those can be selected can not be selected. That is, when the width of the road is wide, there is a large room for selecting a trajectory of the vehicle realized by a certain rudder angle and not following the shape of the curve section. In addition, when the road is narrow, there is less room for selecting a trajectory of the vehicle realized by a certain steering angle and not following the shape of the curve section. Therefore, even if the measured value is stable, it can be said that the narrower the road width, the higher the probability that the curvature specified from the measured value is correct. Therefore, the curvature is specified based on the measured value, and the longer the section where the measured value is stable, the higher the reliability of the curvature, and the narrower the road, the higher the reliability of the curvature. It will be considered.

すなわち、センサの測定値あるいは地図情報に基づいて車両が走行した道路の道路幅を特定し、上述のように測定値が安定している区間の長さに応じた度数を特定した後、道路幅が６ｍより大きい場合には特定された度数に対して係数０．９を乗じる。道路幅が３．５ｍ以上６ｍ以下であれば度数に対して係数１．０を乗じ、道路幅が２ｍ以上であるとともに３．５ｍより小さければ度数に対して係数１．２を乗じる。以上の結果調整された度数で度数分布を構成して曲率の信頼度を特定すれば、道路幅に応じて正確に信頼度を特定することが可能である。むろん、道路幅に応じた信頼度の調整も種々の調整法を採用可能であり、度数を調整することによって間接的に信頼度を調整する構成の他、信頼度自体を直接的に調整する構成としても良い。 Table 2 shows frequency information when the reliability of the curvature is adjusted according to the road width. In this example, the frequency value to be increased in the frequency distribution of the curvature is shown as in the above-described embodiment. The configuration to adjust is adopted. Table 2 shows the coefficient values that are further multiplied by the frequency after the frequency is specified according to the length of the section in which the measured value is stable.

That is, after specifying the road width of the road on which the vehicle has traveled based on the measured value of the sensor or the map information, and specifying the frequency according to the length of the section where the measured value is stable as described above, Is greater than 6 m, the specified frequency is multiplied by a factor of 0.9. If the road width is 3.5 m or more and 6 m or less, the frequency is multiplied by a factor of 1.0, and if the road width is 2 m or more and smaller than 3.5 m, the frequency is multiplied by a factor of 1.2. If the frequency distribution is configured with the frequency adjusted as a result and the reliability of curvature is specified, the reliability can be specified accurately according to the road width. Of course, various adjustment methods can be used to adjust the reliability according to the road width. In addition to the configuration that adjusts the reliability indirectly by adjusting the frequency, the configuration that directly adjusts the reliability itself It is also good.

  DESCRIPTION OF SYMBOLS 10 ... Navigation apparatus, 20 ... Control part, 21 ... Road information learning program, 21a ... Measurement value acquisition part, 21b ... Stable area specific part, 21c ... Road information specific part, 21d ... Reliability degree specific part, 30 ... Recording medium, 30a ... Map information, 30b ... Measurement value information, 30c ... Distribution information, 30d ... Frequency information, 41 ... GPS receiver, 42 ... Vehicle speed sensor, 43 ... Gyro sensor, 44 ... Steering sensor, 45 ... Acceleration sensor, 46 ... Shifting Part, 47 ... braking part

Claims (7)

A measurement value acquisition means for acquiring a measurement value of a sensor mounted on the vehicle;
A stable interval specifying means for specifying an interval in which the measured value is stable;
Road information specifying means for specifying road information of a road on which the vehicle has traveled based on the measured value;
A reliability specifying means for associating higher reliability with the road information as the section is longer;
A road information learning device comprising: The stable section specifying means specifies a section in which a change amount of the measurement value per reference unit is within a predetermined range as the stable section.
The road information learning device according to claim 1. The sensor includes a first sensor and a second sensor different from the first sensor,
The stable section specifying means specifies a section where the measurement value of the first sensor is stable,
The road information specifying means specifies the road information based on a measurement value of the second sensor,
The reliability specifying means associates higher reliability with the road information as the section where the measurement value of the first sensor is stable is longer.
The road information learning device according to claim 2. The first sensor includes a steering sensor that measures a steering angle of a steering mounted on the vehicle,
The second sensor includes a vehicle speed sensor that measures a vehicle speed of the vehicle and an acceleration sensor that measures acceleration acting on the vehicle,
The stable section specifying means specifies a section where the rudder angle is constant,
The road information specifying means specifies curvature information indicating a curvature of the road based on the vehicle speed and the acceleration in a section where the rudder angle is constant,
The reliability specifying means associates higher reliability with the curvature information as the section where the steering angle is constant is longer.
The road information learning device according to claim 3. The reliability specifying means associates higher reliability with the curvature information as the width of the road is narrower.
The road information learning device according to claim 4. A measurement value acquisition step of acquiring a measurement value of a sensor mounted on the vehicle;
A stable interval specifying step for specifying an interval in which the measured value is stable;
A road information specifying step for specifying road information of a road on which the vehicle has traveled based on the measured value;
A reliability specifying step of associating higher reliability with the road information as the section is longer;
A road information learning method comprising: A measurement value acquisition function for acquiring a measurement value of a sensor mounted on the vehicle;
A stable interval specifying function for specifying an interval in which the measured value is stable;
A road information specifying function for specifying road information of a road on which the vehicle has traveled based on the measurement value;
A reliability specifying function that associates higher reliability with the road information as the section is longer,
A road information learning program that makes computers realize.

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