JP2009145186A - Radio wave diffraction estimation device, radio wave diffraction estimation system, computer program, and radio wave diffraction estimation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio wave diffraction estimation device, a radio wave diffraction estimation system, a computer program, and a radio wave diffraction estimation method capable of estimating a diffraction degree of a radio wave from a transmitter, and specifying accurately a vehicle location corresponding to estimation results. <P>SOLUTION: A control part 30 acquires shape information and location information of a peripheral vehicle 300, determines a prediction location of own vehicle, and specifies a virtual straight line with the transmitter 200. The control part 30 receives a radio wave from the transmitter 200, and determines a radio wave positioning location. The control part 30 specifies a virtual shielding surface by the peripheral vehicle 300 based on the shape information, an inter-vehicle distance, the virtual straight line or the like of the peripheral vehicle 300, and calculates a diffraction angle θ of the radio wave based on the virtual shielding surface, the virtual straight line or the like. The control part 30 sets a weighting coefficient corresponding to the calculated diffraction angle, and specifies the own vehicle location based on the set weighting coefficient, the prediction location and the radio wave positioning location. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for measuring a position by receiving a radio wave, and more particularly, a radio wave diffraction estimation apparatus capable of estimating a position of a radio wave diffraction and determining a position with high accuracy even when the radio wave is shielded, and the radio wave diffraction The present invention relates to a radio wave diffraction estimation system including an estimation device, a computer program for realizing the radio wave diffraction estimation device, and a radio wave diffraction estimation method.

Conventionally, in order to prevent traffic accidents between vehicles in and around the intersection or between a vehicle and a pedestrian, the display information of the light color of the traffic light installed at the intersection is used for vehicles traveling toward the intersection. Whether the vehicle can be safely stopped before the intersection based on the received display information, or the vehicle can safely pass through the intersection. There is a system that determines whether or not the vehicle can be operated and alerts the driver with voice according to the determination result. In addition, a traffic light-linked vehicle speed control device that determines whether or not it is possible to safely pass an intersection based on the display information of the traffic signal received by the in-vehicle device and performs vehicle brake control according to the determination result is provided. It has been proposed (see Patent Document 1).
Japanese Patent No. 2806801

  When the vehicle is safely stopped before the intersection, it is necessary to stop the vehicle surely before the stop line provided near the intersection, and it is necessary to accurately grasp the distance from the vehicle to the stop line. However, in the apparatus of Patent Document 1, since the distance from the vehicle to the stop line cannot be accurately determined even when the vehicle is decelerated automatically, the vehicle is surely stopped before the stop line. This is difficult and may cause problems such as overrun. For this reason, in the conventional technology, there has been an inadequate aspect for preventing the traffic accident at the intersection by surely stopping the vehicle before the stop line.

  On the other hand, there is a technique for transmitting a predetermined radio wave from a transmitter and receiving the radio wave to determine the position of the own vehicle. However, in general road traffic situations, there are many vehicles running around the host vehicle. For example, when a large vehicle is running near the host vehicle, the large vehicle may Radio waves will be shielded. For this reason, direct waves cannot be received by the own vehicle, and diffracted waves or reflected waves are received, so that the position of the vehicle cannot be accurately measured, and erroneous own vehicle position information is recognized as correct position information. There was a problem of keeping holding it.

  The present invention has been made in view of such circumstances, and a radio wave diffraction estimation apparatus capable of estimating the degree of radio wave diffraction from a transmitter and accurately identifying the position of a vehicle according to the estimation result, An object is to provide a radio wave diffraction estimation system including a radio wave diffraction estimation apparatus, a computer program for realizing the radio wave diffraction estimation apparatus, and a radio wave diffraction estimation method.

  A radio wave diffraction estimating apparatus according to a first aspect of the present invention is a radio wave diffraction estimating apparatus that estimates the degree of diffraction of a radio wave transmitted from a transmitter, comprising: transmitter information acquiring means for acquiring position information of the transmitter; Measuring means for measuring a position, peripheral object information acquiring means for acquiring shape information and position information of a peripheral object existing around itself, position information of the transmitter, own measurement position, and shape information of the peripheral object And diffraction estimation means for estimating the degree of diffraction of radio waves by the peripheral object based on the position information.

  According to a second aspect of the present invention, there is provided the radio wave diffraction estimating apparatus according to the first aspect, wherein a straight line specifying unit that specifies a virtual straight line connecting the position of the transmitter and the measured position of the transmitter and a virtual shield that blocks radio waves by the peripheral object. Shielding means specifying means for specifying a surface, and the diffraction estimating means is configured to estimate the degree of diffraction of radio waves based on the virtual straight line and the virtual shielding surface.

  A radio wave diffraction estimation apparatus according to a third invention is characterized in that, in the first invention or the second invention, the radio wave diffraction estimation device comprises position specifying means for specifying its position based on the degree of diffraction of the radio wave estimated by the diffraction estimation means. .

  According to a fourth aspect of the present invention, there is provided the radio wave diffraction estimating apparatus according to the third aspect, further comprising: a receiving unit that receives the radio wave transmitted from the transmitter; and a road information acquisition unit that acquires road shape information relating to the road shape. The means has a first measurement means for measuring its own position based on the radio wave received by the receiving unit and the road shape information, and a measurement function different from the first measurement means, and measures the position of itself. The position specifying means weights the position measured by each of the first measuring means and the second measuring means according to the degree of diffraction of the radio wave estimated by the diffraction estimating means. It is characterized by specifying.

  According to a fifth aspect of the present invention, there is provided the radio wave diffraction estimating apparatus according to the fourth aspect, wherein the reliability of the position of the vehicle measured by the first measuring means is determined based on the degree of diffraction of the radio wave estimated by the diffraction estimating means. It is characterized by comprising a degree determination means.

  A radio wave diffraction estimating apparatus according to a sixth invention is the diffraction point for calculating a diffraction point on the outer periphery of the virtual shielding surface based on the intersection of the virtual straight line and the virtual shielding surface in the fourth invention or the fifth invention. Calculating means; and first distance calculating means for calculating a distance between the transmitter and its own position before measurement, wherein the first measuring means includes a distance between the transmitter and a diffraction point, and the diffraction point. The present invention is characterized in that its own position is measured so that the total distance of the distance to its own position after measurement is equal to the distance calculated by the first distance calculating means.

  The radio wave diffraction estimation apparatus according to a seventh aspect of the present invention is the radio diffraction estimation apparatus according to any one of the fourth to sixth aspects, wherein the peripheral object is based on a position on the virtual shielding surface of the intersection of the virtual straight line and the virtual shielding surface. A diffraction angle calculation means for calculating a diffraction angle of a radio wave is provided, and the diffraction estimation means is configured to estimate the degree of diffraction according to the diffraction angle calculated by the diffraction angle calculation means.

  A radio wave diffraction estimating apparatus according to an eighth invention according to any one of the fourth to seventh inventions, further comprising distance information acquisition means for acquiring distance information to the surrounding object, wherein the second measurement means is the It is configured to measure its own position based on the position information of the surrounding object and the distance information acquired by the distance information acquisition means.

  A radio wave diffraction estimation system according to a ninth aspect includes the radio wave diffraction estimation device according to any one of the first to eighth inventions, and a transmitter that transmits radio waves to the radio wave diffraction estimation device. To do.

  A computer program according to a tenth invention is a computer program for causing a computer to estimate the degree of diffraction of a radio wave transmitted from a transmitter, wherein the computer is connected to a virtual straight line connecting the position of the transmitter and its own position. A straight line specifying means for specifying, a shielding surface specifying means for specifying a virtual shielding surface for shielding radio waves by the peripheral object based on shape information and position information of the peripheral object existing in the vicinity thereof, the virtual straight line and the virtual Based on a shielding surface, it functions as a diffraction estimating means for estimating the degree of diffraction of radio waves by the surrounding object.

  A radio wave diffraction estimation method according to an eleventh aspect of the invention is a radio wave diffraction estimation method for estimating the degree of diffraction of a radio wave transmitted from a transmitter, obtains position information of the transmitter, measures its own position, The shape information and position information of a peripheral object existing in the vicinity of the object is acquired, and the degree of radio wave diffraction by the peripheral object based on the position information of the transmitter, its own measurement position, and the shape information and position information of the peripheral object Is estimated.

  In the first invention, the tenth invention, and the eleventh invention, the radio wave diffraction estimating apparatus includes the transmitter position information (for example, the absolute position or the relative position of the transmitter antenna of the transmitter), itself (for example, the own vehicle). Shape information (for example, three-dimensional information such as the length, width, and height of the surrounding vehicle) and position information (for example, an absolute position or a relative position of the surrounding vehicle, The distance between the vehicle and the surrounding vehicle is acquired, and the position of the vehicle (own vehicle) is measured. The location information of the transmitter may be included in the radio wave transmitted by the transmitter, or can be acquired from a roadside device such as an optical beacon. In addition, information on surrounding vehicles can be acquired by inter-vehicle communication, and the inter-vehicle distance can be measured by an in-vehicle sensor mounted on the host vehicle. The position of the host vehicle is, for example, information on the position of the host vehicle output from a car navigation system, information on a communication point with a roadside device such as an optical beacon, or position information measured by receiving a GPS satellite signal. Etc. can be measured. In addition, the position of the host vehicle can be measured by the position of the surrounding vehicle and the inter-vehicle distance between the surrounding vehicle. Note that the measured position of the host vehicle indicates the approximate position of the host vehicle to the last, and is a previous stage of specifying the position of the host vehicle with high accuracy.

  The radio wave diffraction estimation device estimates the degree of diffraction of radio waves by the surrounding vehicle based on the position information of the transmitter, the measurement position of the own vehicle, and the shape information and position information of the surrounding vehicle. For example, the position (direction) of the transmitter viewed from the host vehicle can be obtained based on the position of the transmitter and the measured position of the host vehicle. The presence or absence of radio wave diffraction can be determined based on whether the position of the transmitter viewed from the host vehicle is on a shielding surface shielded by the shape (height, length, width, etc.) of the surrounding vehicle. . For example, the diffraction angle of a radio wave can be obtained from the positions of a transmitter, a shield, and a receiver, and the diffraction degree of the radio wave can be determined from the obtained diffraction angle. As a result, when receiving the radio wave from the transmitter in the own vehicle and measuring the position of the own vehicle, it can be estimated whether the accuracy of the measured position is high or contains a large error, It is possible to prevent the wrong vehicle position information from being held while being recognized as the correct position information.

  In the second aspect of the invention, the radio wave diffraction estimating apparatus specifies a virtual straight line connecting the position of the transmitter and the measurement position of the host vehicle, and specifies a virtual shielding surface that shields the radio wave from surrounding vehicles. For example, the virtual shielding surface can be obtained by flattening the shape represented by the length, height, width, etc. of the surrounding vehicle in the direction of the virtual straight line (the direction when the transmitter is viewed from the host vehicle). The radio wave diffraction estimation apparatus estimates the degree of radio wave diffraction based on a virtual straight line and a virtual shielding surface. For example, when there is an intersection between a virtual straight line and a virtual shielding surface, it can be estimated that there is radio wave diffraction, and when there is no intersection, it can be estimated that there is no radio wave diffraction. For example, the diffraction angle of a radio wave can be obtained from the positions of a transmitter, a shield, and a receiver, and the diffraction degree of the radio wave can be determined from the obtained diffraction angle. As a result, when receiving the radio wave from the transmitter in the own vehicle and measuring the position of the own vehicle, it can be estimated whether the accuracy of the measured position is high or contains a large error, It is possible to prevent the wrong vehicle position information from being held while being recognized as the correct position information.

  In the third aspect of the invention, the radio wave diffraction estimating apparatus specifies its own position based on the estimated degree of radio wave diffraction. For example, when there is no diffraction of radio waves, the position where the radio waves are received (radio wave positioning position) can be set as the position of the host vehicle. In this case, for example, the position of the host vehicle is on a spherical surface centered on the position of the transmitter and having a radius corresponding to the arrival time of the radio wave. By combining this with road shape information of the road on which the host vehicle is traveling, the position of the host vehicle can be specified. If there is radio wave diffraction, the position of the vehicle can be specified by correcting the radio wave positioning position according to the degree of diffraction. In this case, the vehicle position can be determined such that the linear distance between the transmitter and the radio wave positioning position is equal to the propagation distance of the diffracted wave. Thereby, even when radio wave diffraction occurs, the vehicle position can be specified with high accuracy.

  In the fourth invention, the first measuring means measures its own position (radio wave positioning position) based on the radio wave received by the receiving unit and the road shape information. For example, the radio wave positioning position measured by the first measuring means is a combination of a spherical surface centered on the position of the transmitter and having a radius corresponding to the arrival time of the radio wave received by the receiving unit, and road shape information of the road. Can be obtained. The second measuring means does not measure the position by receiving radio waves. For example, information on the position of the vehicle output from the car navigation system, information on a communication point with a roadside device such as an optical beacon, or GPS It can be measured by position information received by receiving satellite signals. The position measured by the second measuring means is only a rough one and is the predicted position of the host vehicle. The radio wave diffraction estimating apparatus weights the positions measured by the first measuring means and the second measuring means according to the degree of radio wave diffraction, and specifies the position of the host vehicle. For example, when the radio wave diffraction degree is small or there is no diffraction, the radio wave positioning position is specified as the own vehicle position without using the predicted position (the weight for the predicted position is set to 0). Further, as the degree of radio wave diffraction increases, the weight of the radio wave positioning position is decreased, and the weight of the predicted position is increased to identify the own vehicle position. When the degree of radio wave diffraction further increases, the predicted position is specified as the vehicle position without using the radio wave positioning position (the weighting for the radio wave positioning position is set to 0). Thereby, the own vehicle position can be specified with high accuracy according to the degree of diffraction of radio waves.

  In the fifth invention, the radio wave diffraction estimating apparatus determines the reliability of the radio wave positioning vehicle measured by the first measuring means based on the estimated radio wave diffraction degree. For example, the greater the degree of diffraction, the smaller (lower) the reliability of radio wave positioning. Thereby, the weighting value for the radio wave positioning position can be determined according to the reliability, and the own vehicle position can be accurately identified according to the degree of radio wave diffraction.

  In the sixth invention, the radio wave diffraction estimating apparatus calculates a diffraction point on the outer periphery of the virtual shielding surface of the radio wave based on the intersection of the virtual straight line and the virtual shielding surface. The radio wave diffraction estimator is such that the total distance of the distance between the transmitter and the diffraction point and the distance between the diffraction point and its own position after measurement is equal to the distance between the transmitter and its own position before measurement. Measure the position of. Thus, the radio wave positioning position is corrected in consideration of an error due to the radio wave propagation path. If there are a plurality of candidates for correction positions, for example, one correction position can be determined from the candidates using road information (shape, height, lane position, etc.). Thereby, the error of the propagation path of the radio wave included in the radio wave positioning can be excluded, and the own vehicle position can be specified with high accuracy.

  In the seventh invention, the radio wave diffraction estimating apparatus calculates a diffraction angle of the radio wave based on a position on the virtual shielding surface at the intersection of the virtual straight line and the virtual shielding surface, and diffracts according to the calculated diffraction angle. Estimate the degree. For example, the peripheral point on the periphery of the virtual shielding surface with the shortest distance from the intersection is obtained, and the angle formed by the straight line connecting the transmitter and the peripheral point and the straight line connecting the peripheral point and the receiving unit is obtained as the diffraction angle. be able to. Thereby, the degree of radio wave diffraction can be accurately estimated regardless of the shape of the surrounding vehicle and the positional relationship of the surrounding vehicle between the transmitter and the receiving unit.

  In the eighth invention, the second measuring means measures the position of the host vehicle based on the position information and distance information of the surrounding vehicle (for example, the inter-vehicle distance from the host vehicle). In this case, the position information of the surrounding vehicle can be acquired from the surrounding vehicle by inter-vehicle communication, and the inter-vehicle distance can be acquired by an in-vehicle sensor such as an in-vehicle camera or an ultrasonic sensor mounted on the own vehicle. Thereby, the predicted position of the host vehicle can be acquired following the traveling of the surrounding vehicles.

  In the ninth invention, the transmitter transmits radio waves to the radio wave diffraction estimating apparatus. Thereby, the radio wave diffraction estimating apparatus can identify the position of the host vehicle by receiving the radio wave.

  In the present invention, when the own vehicle receives a radio wave from a transmitter and measures the position of the own vehicle, it is estimated whether the accuracy of the measured position is high or a large error is included. Therefore, it is possible to prevent the erroneous own vehicle position information from being held while being recognized as the correct position information.

  Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments. FIG. 1 is a schematic diagram showing an outline of a radio wave diffraction estimation system according to the present invention. The radio wave diffraction estimation system according to the present invention includes a transmitter 200 installed at a predetermined position and transmitting a predetermined signal (radio wave), an in-vehicle device 100 as a radio wave diffraction estimation device mounted on the own vehicle, and the like. When the host vehicle travels toward the stop line, the in-vehicle device 100 receives the radio wave transmitted from the transmitter 200 and identifies the host vehicle position based on the arrival time of the received radio wave. In particular, when there is a shielding object that blocks the direct wave from the transmitter 200 in the vicinity of the own vehicle (for example, it may be in front of the own vehicle as shown in FIG. Even if it exists, the onboard equipment 100 can pinpoint the own vehicle position with accuracy each time it receives a radio wave. Details of the method for specifying the vehicle position will be described later.

  FIG. 2 is a block diagram showing the configuration of the radio wave diffraction estimation system according to the present invention. The transmitter 200 includes a control unit 210, a transmission unit 220, and the like. For example, the transmission unit 220 transmits radio waves in the VHF / UHF band frequency band to the in-vehicle device 100. The transmission unit 220 includes a crystal oscillator that generates a reference clock signal, a carrier wave generation circuit, a modulation circuit, and the like (not shown), and generates a predetermined signal (for example, a rectangular wave signal having a frequency of about 10 kHz) based on the reference clock signal. Generate.

  The transmission unit 220 performs frequency modulation on a carrier wave (for example, a frequency of about 100 MHz, about 200 MHz, or about 700 MHz) based on the generated signal under the control of the control unit 210, and after modulation through an antenna (not shown) The carrier wave is transmitted. The frequency band used by transmitter 200 is an example, and is not limited to the VHF / UHF band, but may be another frequency band. For example, a 5.8 GHz band allocated exclusively for automobiles may be used, and a frequency band used for a mobile phone, a PHS, or the like may be used.

  The transmitter 200 repeatedly transmits a predetermined signal to the in-vehicle device 100. The timing at which the transmitter 200 transmits a signal can be arbitrarily set. Further, when there is a time zone in which a signal cannot be transmitted based on a predetermined specification, the transmitter 200 repeatedly transmits the signal to the in-vehicle device 100 at a predetermined timing in the time zone in which transmission is possible.

  The peripheral vehicle 300 is a shielding object that shields direct waves among the radio waves transmitted from the transmitter 200 to the in-vehicle device 100. The peripheral vehicle 300 includes a control unit 310, an inter-vehicle communication unit 320, a vehicle information storage unit 330, a vehicle position measurement unit 340, and the like.

  The vehicle position meter side unit 340 includes a GPS receiver, a car navigation system, and the like, measures the position of the vehicle, and stores it in the vehicle information storage unit 330 as vehicle position information. The vehicle position measurement unit 340 may be configured to measure the position of the vehicle according to the communication position with a roadside device such as an optical beacon and the travel history from the communication position.

  The inter-vehicle communication unit 320 has a function of performing inter-vehicle communication with the in-vehicle device 100, and transmits the vehicle information stored in the vehicle information storage unit 330 to the in-vehicle device 100. The vehicle information is, for example, shape information of surrounding vehicles (for example, the height, length, width, etc. of the vehicle) and vehicle position information (for example, absolute position or relative position, distance from the stop line, etc.).

  The in-vehicle device 100 includes a position measurement unit 10, a storage unit 20, a control unit 30, a radio wave diffraction estimation unit 40, a position specifying unit 50, a display unit 60, an operation unit 70, and the like. The position measurement unit 10 includes a radio wave reception unit 11, a road-to-vehicle communication unit 12, a vehicle-to-vehicle communication unit 13, a sensor unit 14, a GPS reception unit 15, a navigation unit 16, and the like. The radio wave diffraction estimating unit 40 includes a virtual straight line specifying unit 41, a virtual shielding surface specifying unit 42, a diffraction angle calculating unit 43, and the like.

  The radio wave receiver 11 receives a signal transmitted from the transmitter 200. More specifically, the radio wave receiving unit 11 includes a demodulation circuit, receives the radio wave transmitted by the transmitter 200, demodulates the received radio wave, and extracts the original signal. The radio wave receiving unit 11 calculates a signal reception time based on the extracted signal, and outputs the calculated reception time to the control unit 30. It is also possible to use the average value or the median value after calculating the reception time points a plurality of times within a predetermined time. According to such a method, it is possible to reduce the influence of noise or the like and obtain a stable reception time point. The signal reception time can be calculated not only at the rising portion of the signal waveform but also at the falling portion.

  FIG. 3 is an explanatory diagram illustrating an example of a data structure included in a signal transmitted by the transmitter 200. As shown in FIG. 3, the signal transmitted by the transmitter 200 includes, for example, a positioning signal (vehicle position specifying signal) for specifying the vehicle position based on the radio wave from the transmitter 200 and a data area. In the data area, a valid flag indicating that the signal is valid, transmission time information specifying the signal transmission time (for example, time format information measured by the transmitter 200, or counting at a predetermined time interval) Counter information, etc.), and information such as transmitter position information. Note that the positioning signal and data may be transmitted at the same time or different times. Further, the location information of the transmitter may be acquired from a roadside device such as an optical beacon instead of the configuration acquired from the transmitter 200.

  FIG. 4 is an explanatory diagram illustrating an example of obtaining a signal reception time point. The upper part of FIG. 4A schematically shows an example of a signal received from the transmitter 200, and the lower part is a replica signal for performing correlation processing (pattern matching) stored in advance in the in-vehicle apparatus 100. As shown in FIG. 4 (a), when the signal received by the in-vehicle device 100 and the replica signal are sampled at a predetermined time interval, and the waveform and the waveform of the replica signal coincide with each other, as shown in FIG. The correlation value of the signal shows a sharp peak. As shown in FIG. 4B, the radio wave reception unit 11 obtains a signal reception time when a sharp peak of the correlation value is obtained. The method for obtaining the reception time point is not limited to time axis correlation processing, and correlation processing in the frequency domain can also be performed. Note that the correlation shown in FIG. 4B includes not only the correlation by the direct wave but also the correlation by the diffracted wave. Here, the diffracted wave is, for example, a radio wave that is received by the radio wave reception unit 11 after being diffracted by a radio wave that travels straight, and is propagated between the transmitter 200 and the radio wave reception unit 11. The case where the route has non-straightness is shown.

  FIG. 5 is an explanatory diagram showing an example of radio wave positioning. When a vehicle equipped with the in-vehicle device 100 is traveling on a road, the control unit 30 grasps a rough existence area of the own vehicle from time to time based on information output from the GPS receiving unit 15, the navigation unit 16, and the like. Note that the grasped existence area has two intersection lines between a spherical surface centered on the position of the transmitter 200 and a virtual traveling surface of the host vehicle, as will be described later, when specifying the radio wave positioning position. , And can be used to determine which intersection line to select as the radio wave positioning position. When a signal (positioning signal) is received from the transmitter 200 at a certain point P1 on the road, the control unit 30 determines that the signal is transmitted from the transmitter 200 to the in-vehicle device depending on the difference between the signal reception time and the transmission time. The arrival time until reaching 100 is calculated. In this case, the signal transmission time can be obtained from the transmission time information included in the signal.

  The control unit 30 calculates the distance L1 from the transmitter 200 by integrating the speed of light with the arrival time of the signal. That is, it can be seen that the position of the point P1 is on the spherical surface Q1 having the radius L1 with the position of the transmitter 200 as the center.

  On the other hand, when the control unit 30 receives a signal from the transmitter 200 and obtains a position from the transmitter 200, the control unit 30 uses the road shape information of the road on which the host vehicle travels and the height information of the vehicle-mounted device 100 to determine the virtual of the host vehicle. Specific driving surface. When the road is a straight road, the virtual traveling surface is a plane, and when the road is curved, the virtual traveling surface is a curved surface.

  The control unit 30 obtains the radio wave positioning position as an intersection line intersecting the spherical surface Q1 and the traveling surface. As shown in the example of FIG. 1, when the transmitter 200 is installed near a stop line (intersection) and road shape information is given for each link, the center point of the spherical surface Q1 is at the end of the link. Therefore, the spherical surface Q1 and the traveling surface usually intersect at one intersection line. Thereby, the position of the own vehicle can be obtained by radio wave positioning only by receiving a signal from one transmitter 200. In FIG. 5, the point P1 is indicated by a cross, but more precisely, since it is an intersection line where the traveling surface and the spherical surface Q1 intersect, the length is approximately equal to the length of the traveling surface in the road width direction. There is a range of minutes. However, in practice, the vehicle is considered to travel substantially in the middle of the lane or road, and therefore, the position of the approximate center in the width direction of the traveling surface may be specified as the position of the own vehicle.

  Assuming that the vehicle continues to travel and receives a signal from the transmitter 200 at the point P2 on the road, the control unit 30 adds the speed of light to the arrival time of the signal as in the case of the point P1, thereby transmitting the signal. The distance L2 from the machine 200 is calculated. That is, it can be seen that the position of the point P2 is on the spherical surface Q2 having the radius L2 with the position of the transmitter 200 as the center.

  On the other hand, when the control unit 30 receives a signal from the transmitter 200 and obtains a position from the transmitter 200, the control unit 30 uses the road shape information of the road on which the host vehicle travels and the height information of the vehicle-mounted device 100 to determine the virtual of the host vehicle. Specific driving surface.

  The control unit 30 determines the radio wave positioning position as an intersection line that intersects the spherical surface Q2 and the traveling surface. Thereafter, by repeating the same operation, the control unit 30 can accurately obtain the radio wave positioning position each time a signal is received from the transmitter 200.

  FIG. 6 is an explanatory diagram showing the concept of radio wave positioning when a transmitter is used. As shown in FIG. 6, the radio wave positioning position exists on the spherical surface Q having a radius that is a distance obtained by integrating the speed of light (or radio wave propagation speed) with the arrival time of the signal from the transmitter 200 to the vehicle-mounted device 100. Next, it is determined where on the spherical surface Q the position of the host vehicle exists.

  The in-vehicle device 100 specifies the virtual traveling surface S of the own vehicle from the road shape information of the road on which the own vehicle is traveling and the height information of the in-vehicle device 100.

  FIG. 7 is an explanatory diagram showing the structure of road shape information. As shown in FIG. 7, the road shape information is configured by dividing a road into sections of a predetermined distance (for example, 20 m) by a plurality of nodes and information such as distance, gradient, and curvature for each section. When the road is a straight line, nodes are set on one straight line along the road, and when the road is a curve, nodes (for example, two nodes) are set on a plurality of straight lines along the road. Thereby, even when the road is inclined by the curve, the plane determined by the two straight lines can be specified.

  The control unit 30 can set the intersection line where the spherical surface Q and the virtual traveling surface S intersect as the radio wave positioning position. The traveling surface S specified by the road shape information has a belt-like shape and the width thereof is equal to or less than the road width, and the radio wave positioning position can be obtained with high accuracy by specifying the intersection line. In addition, the shape of the running surface S is not limited to a belt shape.

  In addition, as shown in FIG. 6, when two intersecting lines where the spherical surface Q and the traveling surface S intersect are specified, the radio wave positioning position can be specified as follows. That is, there are two intersecting lines between the spherical surface Q and the traveling surface S. One of these is information that does not have high accuracy, such as the previous positioning result, the subsequent traveling history, and the positioning result with the GPS receiver. However, it can be determined sufficiently.

  The control unit 30 is information on the vehicle position obtained from the signal received by the GPS reception unit 15, information on the vehicle position output from the navigation unit 16 or the like, or information on a communication point with a roadside device such as an optical beacon. Thus, the existence area of the own vehicle can be narrowed down. For example, an own vehicle position (positioning point) obtained by receiving a GPS satellite signal and a region within a predetermined position error centered on the positioning point (for example, a region having a radius of 10 m centered on the positioning point). Narrow down as the existence area of the own vehicle. The intersecting line in the narrowed existence area can be obtained as the radio wave positioning position.

  As another method, the control unit 30 can narrow down the existence area of the own vehicle based on the latest vehicle position specified most recently and the travel history from that point. For example, when the vehicle has traveled 100 m from the most recently specified vehicle position, an area within a position error associated with travel centered on the predicted travel point after 100 m travel (for example, a region with a radius of 10 m centered on the predicted travel point). Narrow down as the existence area of the own vehicle. The intersecting line in the narrowed existence area can be obtained as the radio wave positioning position. In addition, the position error accompanying traveling can be changed according to the reliability of the autonomous sensor such as the wheel speed.

  The road-vehicle communication unit 12 has a communication function with roadside devices such as an optical beacon, a radio beacon, and a DSRC. For example, by communication with an optical beacon, it is possible to receive communication point position information, position information of the transmitter 200, stop line position information, road shape information regarding the road shape, and the like. The road-to-vehicle communication unit 12 may have not only a narrow-area communication function but also a mid-range communication function and a wide-area communication function.

  The inter-vehicle communication unit 13 has a communication function with the surrounding vehicle 300 and receives vehicle information from the surrounding vehicle 300. As a result, when the predicted position of the host vehicle is obtained based on the inter-vehicle distance between the position measured by the surrounding vehicle 300 and the surrounding vehicle 300, the predicted position of the host vehicle can be obtained following the travel of the surrounding vehicle 300.

  The sensor unit 14 includes in-vehicle sensors such as a wheel speed sensor, a gyro sensor, and an acceleration sensor, and functions as an autonomous sensor that can record a travel history and obtain the position of the host vehicle at any time. The sensor unit 14 can also include an in-vehicle camera, an ultrasonic sensor, and the like. Thereby, the inter-vehicle distance with the surrounding vehicle 300 can be measured.

  The GPS receiver 15 has a GPS receiving function such as DGPS (differential GPS) or RTK-GPS (Real-Time Kinematic GPS), and repeatedly receives radio waves from a GNSS (Global Navigation Satellite System) satellite including a plurality of GPSs. Measure the vehicle position. Note that the existence area of the own vehicle may vary depending on the accuracy of the GPS receiver 15 and the status of received radio waves.

  The navigation unit 16 has a built-in map database and the like, and based on information from the GPS receiver 15 and information from the sensor unit 14, the vehicle's travel history (for example, travel distance, travel direction, travel recorded with time) Speed, acceleration / deceleration, etc.).

  The storage unit 20 stores information received through the radio wave receiving unit 11, the road-to-vehicle communication unit 12, the vehicle-to-vehicle communication unit 13, and the like. The storage unit 20 stores in advance height information of the mounting position of the in-vehicle device 100 (for example, the reception antenna of the radio wave reception unit 11).

  The virtual straight line specifying unit 41 includes the position of the own vehicle (predicted position) and the position of the transmitter 200 measured by the road-to-vehicle communication unit 12, the vehicle-to-vehicle communication unit 13, the sensor unit 14, the GPS receiving unit 15, the navigation unit 16, and the like. A virtual straight line connecting the two is specified.

  The virtual shielding surface specifying unit 42 identifies the shape represented by the length, height, width, etc. of the surrounding vehicle 300 by the virtual straight line specifying unit 41 (the direction in which the transmitter 200 is viewed from the own vehicle). The virtual shielding surface is specified by flattening. The virtual shielding surface is a surface where the position of the transmitter 200 viewed from the host vehicle is shielded by the shape (height, length, width, etc.) of the surrounding vehicle 300.

  The diffraction angle calculation unit 43 calculates the radio wave diffraction angle based on the position on the virtual shielding surface of the intersection of the virtual straight line specified by the virtual straight line specification unit 41 and the virtual shielding surface specified by the virtual shielding surface specification unit 42. . The diffraction angle is obtained, for example, by obtaining a peripheral point on the periphery of the virtual shielding surface with the shortest distance from the intersection on the virtual shielding surface, a straight line connecting the transmitter 200 and the peripheral point, and the position of the surrounding point and the vehicle ( The angle formed by the straight line connecting the (predicted position) can be obtained as the diffraction angle. Thereby, regardless of the shape of the surrounding vehicle 300, the positional relationship of the surrounding vehicle 300 between the transmitter 200 and the vehicle-mounted device 100, or the like, that is, regardless of the shape of the virtual shielding surface, the point where the radio wave is diffracted is specified. Therefore, the degree of radio wave diffraction (the degree of non-straightness of the radio wave propagation path) can be accurately estimated.

  FIG. 8 is an explanatory diagram illustrating an example in which radio waves from the transmitter 200 are shielded. As shown in FIG. 8, when the position of the in-vehicle device 100 is at the point P <b> 1, radio waves from the transmitter 200 are not shielded by the surrounding vehicle 300, and the in-vehicle device 100 transmits a direct wave from the transmitter 200. Can be received. On the other hand, when the position of the in-vehicle device 100 is at the point P2, the radio wave from the transmitter 200 is shielded by the surrounding vehicle 300, and the in-vehicle device 100 cannot receive the direct wave from the transmitter 200, and is diffracted. You will receive waves.

  FIG. 9 is an explanatory diagram showing a calculation example of the diffraction angle of the radio wave from the transmitter 200. The position of the transmitter 200 is (X0, Y0, Z0), and the predicted position of the in-vehicle device 100 is (X1, Y1, Z1). Here, the expected position is the position of the own vehicle measured by an optical beacon, an in-vehicle sensor, vehicle-to-vehicle communication with the surrounding vehicle 300, and excludes the radio wave reception position measured by the radio wave from the transmitter 200.

  The virtual straight line L can be specified as a straight line connecting the predicted position of the in-vehicle device 100 and the position of the transmitter 200.

  The virtual shielding surface R can be specified by planarizing the three-dimensional shape of the surrounding vehicle 300 in the direction of the virtual straight line L (the direction in which the transmitter 200 is viewed from the in-vehicle device 100). For example, when the host vehicle on which the vehicle-mounted device 100 is mounted is running behind the surrounding vehicle 300, when the position of the transmitter 200 is ahead in the road direction, the width, height, A substantially rectangular surface defined by an inter-vehicle distance from the vehicle 300 can be used as the virtual shielding surface R. If the positions of the four corners of the virtual shielding surface R are A (Xa, Ya, Za), B (Xb, Yb, Zb), C (Xc, Yc, Zc), D (Xd, Yd, Xd), the length of AD The length of BC and the length of BC substantially correspond to the width of the surrounding vehicle 300, and the length of AB and the length of CD substantially correspond to the height of the surrounding vehicle 300 from the road surface.

  A virtual intersection E (Xe, Ye, Ze) between the virtual shielding surface R and the virtual straight line L determined at positions A to D, and a peripheral point F on the periphery of the virtual shielding surface R having the shortest distance from the virtual intersection E (Xf, Yf, Zf) is obtained, and an angle formed by a straight line connecting the transmitter 200 and the peripheral point F and a straight line connecting the peripheral point F and the vehicle-mounted device 100 can be obtained as the diffraction angle θ.

  Note that the virtual shielding surface R is not limited to the rear surface of the surrounding vehicle 300. When the surrounding vehicle 300 is traveling in the adjacent lane of the own vehicle, the position of the transmitter 200 is the surrounding vehicle 300. When the vehicle is in the lateral direction of the host vehicle, the virtual shielding surface R is defined by the length and height of the surrounding vehicle 300. When the surrounding vehicle 300 is traveling diagonally forward of the host vehicle and the position of the transmitter 200 is diagonally forward of the host vehicle with the peripheral vehicle 300 in between, the virtual shielding surface R is It is defined by a length, width and height of 300. In this case, the shape of the virtual shielding surface R is not limited to a rectangular shape, and, for example, the line segment AD is refracted into a mountain shape in the middle to become a substantially pentagonal shape.

  The radio wave diffraction estimation unit 40 estimates the degree of radio wave diffraction according to the diffraction angle calculated by the diffraction angle calculation unit 43, and outputs the estimation result to the control unit 30.

  The position specifying unit 50 includes the radio wave positioning position measured by the radio wave receiving unit 11 and the predicted position measured by the road-to-vehicle communication unit 12, the inter-vehicle communication unit 13, the sensor unit 14, the GPS receiving unit 15, the navigation unit 16, and the like. On the other hand, weighting is performed based on the degree of diffraction estimated by the radio wave diffraction estimation unit 40, and the position of the own vehicle is specified.

  More specifically, the position specifying unit 50 calculates a linear distance R1 between the transmitter 200 and the radio wave positioning position before correction measured by the radio wave receiving unit 11. Next, the position specifying unit 50 calculates a total distance R2 between the distance between the transmitter 200 and the peripheral point F (radio wave diffraction point) and the distance between the peripheral point F and the corrected radio wave position. The position specifying unit 50 corrects the radio wave positioning position so that the calculated distances R1 and R2 are equal. Thereby, the error of the propagation path of the radio wave included in the radio wave positioning can be excluded.

  That is, when there is radio wave shielding, the radio wave positioning position is corrected, and when there is no radio wave shielding, the radio wave positioning position is used without being corrected. The position specifying unit 50 specifies (determines) the position of the vehicle by weighting the radio wave positioning position (including correction) and the predicted position based on the degree of radio wave diffraction. Thereby, the own vehicle position can be specified with high accuracy.

  In this case, when there are a plurality of candidates as correction positions, one correction position can be determined from the candidates using road information (shape, height, lane position, etc.). Further, a correction position on the road that is closest to the predicted position may be determined as the correction position. Hereinafter, a method for specifying the vehicle position according to the degree of diffraction of radio waves will be described.

  FIG. 10 is an explanatory diagram showing an example of the relationship between the diffraction angle and the path error. In FIG. 10, the horizontal axis indicates the diffraction angle, and the vertical axis indicates the path error. The path error can be, for example, the difference between the linear distance between the in-vehicle device 100 and the transmitter 200 and the propagation distance of the diffracted wave diffracted by the peripheral vehicle 300. As shown in FIG. 10, the path error increases as the diffraction angle increases, and the path error becomes the largest when the inter-vehicle distance from the surrounding vehicle 300 that shields radio waves becomes zero. Further, the route error increases as the inter-vehicle distance from the surrounding vehicle 300 becomes shorter.

  As the path error increases, the measurement error in receiving the radio wave from the transmitter 200 and measuring the position by the distance corresponding to the propagation time of the received radio wave increases, and the accuracy of the radio wave positioning position, that is, the own vehicle position. Decreases. Hereinafter, an example of a method for specifying the own vehicle position when the radio wave from the transmitter 200 is shielded by the surrounding vehicle 300 or the like will be described.

  FIG. 11 is an explanatory diagram showing an example of specifying the vehicle position when there is no diffraction of radio waves. In FIG. 11, the radio wave positioning position determined by the radio wave from the transmitter 200 is P3 (X3, Y3, Z3). On the other hand, let P4 (X4, Y4, Z4) be the predicted position where the vehicle position is measured by a method other than radio wave positioning.

  As shown in FIG. 11, when there is no radio wave diffraction, the predicted position P4 is not shielded by the surrounding vehicle 300, is outside the surrounding vehicle 300, and is not shielded at the radio wave positioning position P3. The radio wave from the transmitter 200 can be received, and the radio wave position P3 is identified as the own vehicle position without correction.

  FIG. 12 is an explanatory diagram showing an example of specifying the vehicle position when there is a diffraction angle of radio waves. In FIG. 12, the radio wave positioning position measured by the radio wave from the transmitter 200 is P5 (X5, Y5, Z5). On the other hand, let P7 (X7, Y7, Z7) be the predicted position where the vehicle position is measured by a method other than radio positioning.

  When the diffraction angle θ, which is an angle formed by a straight line connecting the transmitter 200 and the peripheral point F of the peripheral vehicle 300, and a straight line connecting the peripheral point F and the vehicle-mounted device 100 is not 0, there is a path error due to radio wave diffraction. Therefore, the radio wave positioning position P5 is corrected by the amount of diffraction so that the linear distance r5 between the transmitter 200 and the radio wave positioning position P5 is equal to the propagation distance (r61 + r62) of the diffracted wave, and the corrected radio wave positioning position P6 is corrected. (X6, Y6, Z6) is determined. The own vehicle position is specified by weighting the predicted position P7 and the corrected radio wave position P6 according to the magnitude of the diffraction angle θ. Thereby, the own vehicle position can be specified with high accuracy.

  FIG. 13 is an explanatory diagram showing an example of specifying the vehicle position when the diffraction angle of the radio wave is larger. In FIG. 13, the radio wave positioning position measured by the radio wave from the transmitter 200 is P8 (X8, Y8, Z8). On the other hand, a predicted position obtained by measuring the vehicle position by a method other than radio wave positioning is defined as P9 (X9, Y9, Z9).

  When the diffraction angle θ, which is an angle formed by a straight line connecting the transmitter 200 and the peripheral point F of the peripheral vehicle 300, and a straight line connecting the peripheral point F and the vehicle-mounted device 100 is large, the influence of radio wave attenuation due to diffraction, etc. Therefore, the predicted position P9 is specified as the own vehicle position.

  In this case, the radio wave diffraction estimation unit 40 can be configured to determine the reliability of the radio wave positioning position based on the diffraction angle calculated by the diffraction angle calculation unit 43. Accordingly, as shown in the example of FIG. 13, when the reliability of the radio wave positioning position is small (low), the vehicle position can be obtained using the predicted position without using the radio wave positioning position. When the reliability is low, the weighting for the radio wave positioning position can be reduced. Thereby, the weighting value for the radio wave positioning position can be determined according to the reliability, and the own vehicle position can be accurately identified according to the degree of radio wave diffraction.

  A numerical example will explain how much path error can be excluded by correcting the radio wave positioning position. In the three-dimensional space (X, Y, Z), the position of the transmitter 200 is (0, 0, 6) (the unit is m). That is, it is assumed that the height of the antenna portion of the transmitter 200 is 6 m. The radio wave shielding surface is at a point 60 m from the transmitter 200, and its height is 3.8 m. The predicted position of the host vehicle is 3 m away from the shielding surface, and the height of the receiver is 1.5 m. That is, the predicted position is (63, 0, 1.5). In this case, the radio wave positioning distance is 65 m, the radio wave positioning position before correction is (64.84, 0, 1.5), and the corrected radio wave positioning position is (64.39, 0, 1.5). . That is, the correction can eliminate a path error of about 0.4 m.

  As described above, according to the diffraction angle of the radio wave, the vehicle position can be specified by performing necessary weighting on each of the radio wave positioning position and the predicted position.

  FIG. 14 is an explanatory diagram showing an example of weighting. In FIG. 14, the horizontal axis indicates the diffraction angle, and the vertical axis indicates the weighting count. The weighting coefficient of the radio wave position is α, the weighting coefficient of the predicted position is β, and α + β = 1. The identified own vehicle position can be obtained by α × radio wave position (including corrected radio wave position) + β × predicted position. Note that the curves of α and β are merely examples, and the present invention is not limited thereto.

  As shown in FIG. 14, when the diffraction angle is 0, α = 1 and β = 0, and the radio wave positioning position is the own vehicle position. Also, as the diffraction angle increases, the weight of the radio wave positioning position is reduced. If the diffraction angle further increases, α = 0 and β = 1, and the predicted position is the own vehicle position. Thereby, the own vehicle position can be specified with high accuracy according to the degree of diffraction of radio waves.

  FIG. 15 is an explanatory diagram showing another example of weighting. In this case, when a required angle threshold is set in advance and the diffraction angle is larger than the angle threshold, the predicted position is set as the specified position (final vehicle position), and when the diffraction angle is smaller than the angle threshold. May be a position that specifies the radio wave positioning position. Note that the angle threshold may be set as appropriate according to the reception status of radio waves.

  The display unit 60 is a liquid crystal display panel such as a head-up display, a car navigation system, or a monitoring monitor, and can display various traffic information to the driver. For example, a distance to the intersection or stop line, a warning when the vehicle cannot travel safely at the intersection, and the like are displayed.

  The operation unit 70 includes various operation panels and functions as a user interface between the driver and the vehicle-mounted device 100. For example, the operation unit 70 receives an operation for starting or stopping the operation of the in-vehicle device 100 by the operation of the driver.

  Next, the operation of the in-vehicle device 100 will be described. FIG. 16 is a flowchart showing a processing procedure of the in-vehicle device 100. The control unit 30 acquires shape information and position information of the surrounding vehicle 300 (S11), determines whether or not a signal is received from the transmitter 200 (S12), and if no signal is received (NO in S12) ), The process of step S11 is continued.

  When the signal is received from the transmitter 200 (YES in S12), the control unit 30 calculates the predicted position of the host vehicle (S13), and calculates the radio wave positioning position of the host vehicle based on the received signal (S14). . The control unit 30 identifies a virtual straight line with the transmitter 200 based on the position of the transmitter and the predicted position of the host vehicle (S15).

  The control unit 30 specifies the virtual shielding surface by the surrounding vehicle 300 based on the shape information of the surrounding vehicle 300, the inter-vehicle distance from the surrounding vehicle 300, the virtual line described above, and the like (S16), and the virtual shielding surface and the virtual line A radio wave diffraction angle θ is calculated based on a virtual intersection, a peripheral point of the virtual shielding surface, and the like (S17).

  Based on the calculated diffraction angle, the control unit 30 determines whether or not the radio wave is shielded (S18). If there is a shield (YES in S18), the radio wave positioning position is corrected (S19). When there is no radio wave shielding (NO in S18), the control unit 30 performs the process of Step S20 described later without performing the process of Step S19.

  The control unit 30 sets a weighting coefficient according to the calculated diffraction angle (S20), and determines the vehicle position based on the set weighting coefficient, expected position and radio wave positioning position (including the corrected radio wave positioning position). Specify (S21). The control unit 30 determines whether or not there is an instruction to end the process (S22). If there is no end instruction (NO in S22), the process after step S11 is repeated, and if there is an end instruction (YES in S22), the process is performed. finish.

  As described above, in the present invention, when the own vehicle receives radio waves from the transmitter and measures the position of the own vehicle, the accuracy of the measured position is high or a large error is included. It is possible to prevent the vehicle from holding the wrong vehicle position information while recognizing it as correct position information. Also, even when radio waves are shielded by surrounding vehicles and direct waves cannot be received and diffracted waves are received, the radio wave positioning position is corrected according to the degree of radio wave diffraction to accurately position the vehicle. Can be identified.

  In the above-described embodiment, the configuration is such that the shape information of the surrounding vehicle is acquired from the surrounding vehicle by inter-vehicle communication, but is not limited thereto. For example, shape information is stored in advance corresponding to the vehicle type of the surrounding vehicle (for example, bus, truck, etc.), the vehicle type of the surrounding vehicle is determined by an in-vehicle sensor mounted on the own vehicle, and according to the determined vehicle type Shape information can also be used.

  In the above-described embodiment, when the position of the own vehicle is specified based on the radio wave from one transmitter, the estimation of the degree of diffraction when the radio wave is shielded by the presence of a surrounding vehicle, etc. Although the correction has been described, the present invention is not limited to this, and when the position of the host vehicle is specified using a plurality of transmitters, radio waves from any one or a plurality of transmitters are shielded. The present invention can be applied to such cases. In such a case, if there are a plurality of correction positions, the correction position closest to the predicted position can be specified as the position of the host vehicle.

  In the above-described embodiment, the example of the surrounding vehicle is described as the surrounding object that shields radio waves. However, the surrounding object is not limited to a moving object such as a vehicle. The present invention can also be applied to a case where radio waves are shielded by a building such as a building or an outdoor facility existing between the traveling road. In this case, information such as the height, width, length, and position of the building may be acquired from, for example, a roadside device installed near the building.

  According to the above-described invention, even when the radio wave transmitted from the transmitter is shielded by a surrounding vehicle (for example, a large vehicle), the position of the traveling vehicle can be accurately identified. By using the present invention, for example, it is possible to receive display information of a traffic signal ahead by an in-vehicle device, and whether or not it can be stopped safely before the intersection based on the received display information, or the intersection can be safely Whether or not the vehicle can pass can be determined with high accuracy, and the driver can be alerted by voice according to the determination result. In addition, it is possible to determine with high accuracy whether or not the vehicle can safely pass through the intersection based on the display information of the traffic signal received by the vehicle-mounted device, and to perform vehicle brake control according to the determination result. Accidents can be prevented and traffic safety can be improved.

  In the above-described embodiment, when calculating the diffraction degree, diffraction angle, and propagation path of a radio wave, the geometric optical diffraction theory (GTD) or the uniform diffraction theory (UTD) is used. Diffraction) can also be used.

  The disclosed embodiments are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a schematic diagram which shows the outline | summary of the radio wave diffraction estimation system which concerns on this invention. It is a block diagram which shows the structure of the radio wave diffraction estimation system which concerns on this invention. It is explanatory drawing which shows the example of the data structure contained in the signal which a transmitter transmits. It is explanatory drawing which shows the example which calculates | requires the reception time of a signal. It is explanatory drawing which shows an example of a radio wave positioning. It is explanatory drawing which shows the concept of the radio wave positioning at the time of using a transmitter. It is explanatory drawing which shows the structure of road shape information. It is explanatory drawing which shows the example by which the electromagnetic wave from a transmitter is shielded. It is explanatory drawing which shows the example of calculation of the diffraction angle of the electromagnetic wave from a transmitter. It is explanatory drawing which shows an example of the relationship between a diffraction angle and a path | route error. It is explanatory drawing which shows an example of specification of the own vehicle position when there is no diffraction of an electromagnetic wave. It is explanatory drawing which shows an example of specification of the own vehicle position in case there exists a diffraction angle of an electromagnetic wave. It is explanatory drawing which shows an example of specification of the own vehicle position in case the diffraction angle of an electromagnetic wave is still larger. It is explanatory drawing which shows an example of weighting. It is explanatory drawing which shows the other example of weighting. It is a flowchart which shows the process sequence of a vehicle equipment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Vehicle equipment 10 Position measurement part 11 Radio wave reception part 12 Road-to-vehicle communication part 13 Inter-vehicle communication part 14 Sensor part 15 GPS receiving part 16 Navigation part 20 Storage part 30 Control part 40 Radio wave diffraction estimation part 41 Virtual straight line identification part 42 Virtual shielding Surface identification unit 43 Diffraction angle calculation unit 50 Position identification unit 60 Display unit 70 Operation unit 200 Transmitter 210 Control unit 220 Transmission unit 300 Peripheral vehicle 310 Control unit 320 Inter-vehicle communication unit 330 Vehicle information storage unit 340 Vehicle position measurement unit

Claims (11)

A radio wave diffraction estimating device for estimating the degree of diffraction of radio waves transmitted from a transmitter,
Transmitter information acquisition means for acquiring position information of the transmitter;
A measuring means for measuring its own position;
Peripheral object information acquisition means for acquiring shape information and position information of a peripheral object existing in the vicinity of itself;
Diffraction estimation means for estimating the degree of diffraction of radio waves by the peripheral object based on position information of the transmitter, its own measurement position, and shape information and position information of the peripheral object. apparatus. Straight line specifying means for specifying a virtual straight line connecting the position of the transmitter and the measured position;
Shielding surface specifying means for specifying a virtual shielding surface that shields radio waves by the surrounding objects, and
The diffraction estimation means includes
2. The radio wave diffraction estimation apparatus according to claim 1, wherein the radio wave diffraction estimation apparatus is configured to estimate a radio wave diffraction degree based on the virtual straight line and the virtual shielding surface.   The radio wave diffraction estimation apparatus according to claim 1, further comprising: a position specifying unit that specifies its own position based on a diffraction degree of the radio wave estimated by the diffraction estimation unit. A receiver for receiving radio waves transmitted from the transmitter;
Road information acquisition means for acquiring road shape information related to the road shape,
The measuring means includes
First measuring means for measuring its own position based on the radio wave received by the receiving unit and the road shape information;
A second measuring means having a measuring function different from the first measuring means and measuring its own position;
The position specifying means includes
In accordance with the degree of radio wave diffraction estimated by the diffraction estimating means, the position measured by each of the first measuring means and the second measuring means is weighted to identify its own position. The radio wave diffraction estimation apparatus according to claim 3.   The reliability determination means for determining the reliability of the position of the vehicle measured by the first measurement means based on the diffraction degree of the radio wave estimated by the diffraction estimation means. Radio diffraction estimator. Diffraction point calculating means for calculating a diffraction point on the outer periphery of the virtual shielding surface of the radio wave based on the intersection of the virtual straight line and the virtual shielding surface;
First distance calculating means for calculating a distance between the transmitter and its own position before measurement;
The first measuring means includes
The own position is measured so that the total distance of the distance between the transmitter and the diffraction point and the distance between the diffraction point and the position after measurement is equal to the distance calculated by the first distance calculation means. The radio wave diffraction estimating apparatus according to claim 4, wherein the radio wave diffraction estimating apparatus is configured as follows. A diffraction angle calculating means for calculating a diffraction angle of a radio wave by the peripheral object based on a position on the virtual shielding surface of an intersection of the virtual straight line and the virtual shielding surface;
The diffraction estimation means includes
The radio wave diffraction estimation apparatus according to any one of claims 4 to 6, wherein a diffraction degree is estimated according to a diffraction angle calculated by the diffraction angle calculation means. Distance information acquisition means for acquiring distance information to the surrounding objects,
The second measuring means includes
8. The apparatus according to claim 4, wherein the position of the surrounding object is measured based on the position information of the peripheral object and the distance information acquired by the distance information acquisition unit. The radio wave diffraction estimation apparatus according to 1.   A radio wave diffraction estimation system comprising: the radio wave diffraction estimation apparatus according to claim 1; and a transmitter that transmits radio waves to the radio wave diffraction estimation apparatus. A computer program for causing a computer to estimate the degree of diffraction of radio waves transmitted from a transmitter,
Straight line specifying means for specifying a virtual straight line connecting the computer and the position of the transmitter to the computer;
A shielding surface identifying means for identifying a virtual shielding surface that shields radio waves by the surrounding object based on the shape information and position information of the surrounding object existing around the object;
A computer program that functions as diffraction estimation means for estimating the degree of diffraction of radio waves by the peripheral object based on the virtual straight line and the virtual shielding surface. A radio wave diffraction estimation method for estimating the degree of diffraction of radio waves transmitted from a transmitter,
Obtaining location information of the transmitter;
Measure your position,
Obtain the shape information and position information of the surrounding objects that exist around you,
A radio wave diffraction estimation method, comprising: estimating a degree of radio wave diffraction by the peripheral object based on position information of the transmitter, its own measurement position, and shape information and position information of the peripheral object.

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