JP2017151040A - Direction estimation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a direction estimation device that, even if at least one of other device and own device has three capturing satellites, is able to estimate the direction in which the other device is present.SOLUTION: For each satellite pair establishing, as a population, GNSS satellites captured by the own vehicle, an own vehicle single difference calculation part F1 calculates a single difference that is a difference in pseudo distance between GNSS composing a satellite pair. An other-vehicle single difference specifying part F5 acquires an other-vehicle single difference, which is a single difference for other vehicle, through communication between the vehicles. A double difference calculation part 6 simultaneously calculates a double difference, which is a difference between the single difference of the own vehicle and a single difference of the other vehicle. An other-vehicle direction estimation part F11 estimates, as the direction in which the other vehicle is present, the direction determined from the advancing direction of the own vehicle and an imaginary inclination calculated using coordinate information of the satellite pair (i.e., a pair with the lowest degree of decrease) that is smallest in absolute value among satellite pairs that are negative in a degree of change of double difference per unit time.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a direction estimation device that estimates a direction in which another device that is a communication partner performing wireless communication exists.

  In recent years, each of a plurality of vehicles has transmitted a communication packet indicating vehicle information (hereinafter referred to as own vehicle information) such as a traveling speed of the own vehicle, a current position, and a traveling direction to the other vehicle and has been transmitted from the other vehicle. An inter-vehicle communication system that sequentially receives communication packets (hereinafter, other vehicle information) has been proposed.

  Further, in Patent Document 1, as an apparatus used in such a vehicle-to-vehicle communication system, from the position information of the other vehicle indicated in the communication packet transmitted from the other vehicle and the position information of the own vehicle, An apparatus for specifying the direction in which another vehicle exists is disclosed. The direction in which the specified other vehicle exists is used to determine whether or not the other vehicle may collide with the host vehicle.

  The current position of each vehicle is specified by receiving radio waves from a satellite (hereinafter referred to as a GNSS satellite) used in a global navigation satellite system (GNSS). Generally, in order to identify the current position using radio waves transmitted from GNSS satellites, it is necessary to capture radio waves from four or more GNSS satellites.

JP 2012-22671 A

  In patent document 1, in order to calculate the direction in which the other vehicle exists, it is assumed that each of the own vehicle and the other vehicle can measure the current position. As described above, it is necessary to acquire at least four GNSS satellites for positioning the current position.

  Therefore, when the number of GNSS satellites that can be captured is three or less, the current position cannot be measured, and the direction in which the other vehicle is present cannot be specified.

  The present invention has been made based on this circumstance, and the purpose of the present invention is that even if the number of captured satellites of at least one of the other device and itself is three, the other device exists. An object of the present invention is to provide a direction estimation device capable of estimating a direction to be performed.

  The present invention for achieving the object is a radio wave used in a mobile body and transmitted from a plurality of reference stations respectively located at different positions, and receives radio waves including transmission source information indicating the transmission source of the radio waves. Pseudo-range identification that sequentially identifies the pseudo-range between the receiver (12) and the acquisition reference station, which is a reference station that can receive radio waves, based on the radio waves from the acquisition reference station received by the receiver. When there are three or more acquisition reference stations and the part (121), at least two or more reference station pairs that constitute two acquisition reference stations as one set, pseudo distances to two acquisition reference stations that constitute the reference station pair A self-single-difference calculation unit (F1) that sequentially calculates a self-single-difference that is an absolute value of the difference between them, and a single-difference difference corresponding to the self-single-difference for each reference station pair for other devices A single difference difference acquisition unit (F5) for each other, and a double difference calculation unit (F6) that calculates, for each reference station pair, a double difference that is a difference between the self-single difference corresponding to the reference station pair and the single difference of the other For each reference station pair, a double difference change degree calculation unit (F8) for calculating a change degree indicating a change degree per unit time of the double difference, and the absolute difference among the reference station pairs in which the change degree is negative. A coordinate information acquisition unit (F7) for acquiring coordinates representing the current position in the horizontal orthogonal coordinate system of the two reference stations constituting the minimum decrease pair that is the reference station pair having the minimum value; A β calculation unit (F9) that calculates a parameter β using coordinates and a predetermined formula, a traveling direction acquisition unit (F10) that acquires a traveling direction of the moving object, a parameter β calculated by the β calculating unit, and a moving object Based on the direction of travel, estimate the direction in which other devices exist Another device direction estimation unit (F11).

  The above direction estimation apparatus sequentially calculates the double difference for each reference station pair, and the satellite pair having the smallest absolute value among the reference station pairs in which the change degree of the double difference is negative (that is, the pair with the smallest decrease). ). Then, the azimuth in which the other device exists is estimated from the parameter β calculated using the coordinate information of the reduction degree minimum pair and the traveling direction of the moving body in which the own device is used.

  It has been confirmed by numerical analysis that there is a correspondence relationship between the parameter β calculated using the coordinate information of the minimum decrease pair, the traveling direction of the own device, and the direction in which the other device exists. Therefore, according to the above configuration, it is possible to estimate the direction in which the other device exists from the parameter β calculated using the coordinate information of the minimum decrease pair and the traveling direction of the own device. In addition, the self apparatus in the above points out direction estimation apparatus itself.

  In determining the minimum decrease pair, the own device and the other device only need to capture the three reference stations in common. Therefore, according to the above configuration, even when the number of acquisition reference stations of at least one of the own apparatus and the other apparatus is 3, the direction in which the other apparatus exists can be estimated.

  As the above-mentioned reference station, for example, a satellite (hereinafter referred to as a GNSS satellite) used in the Global Navigation Satellite System (GNSS) or a wireless base for constructing a public wireless communication network such as a cellular phone network is used. You can use the station.

  Even if a GNSS satellite is adopted as the reference station, it is only necessary that the GNSS satellite can be commonly captured by the own apparatus and the other apparatus for the reason described above. That is, according to the above configuration, even when the number of captured satellites is three or less, it is possible to estimate the direction in which another device performing wireless communication with the own device exists.

  In addition, the code | symbol in the parenthesis described in the claim shows the correspondence with the specific means as described in embodiment mentioned later as one aspect, Comprising: The technical scope of this invention is limited is not.

It is a figure which shows schematic structure of the direction estimation system 100 which concerns on this embodiment. 1 is a block diagram illustrating an example of a schematic configuration of an in-vehicle device 1. 2 is a block diagram illustrating an example of a schematic configuration of a control unit 11. FIG. It is a flowchart which shows the transmission process which the control unit 11 implements. It is a graph for demonstrating the relationship between the double difference D and change degree (alpha). It is a figure for demonstrating the correspondence of the virtual inclination (beta) of a minimum reduction degree pair, and another vehicle direction. It is a flowchart for demonstrating other vehicle direction estimation processing. It is a figure for demonstrating the reduction degree minimum pair.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an example of a schematic configuration of a direction estimation system 100 to which the present invention is applied. As shown in FIG. 1, the direction estimation system 100 includes a plurality of GNSS satellites St1 to St3 and a plurality of vehicle-mounted devices 1 mounted on each of a plurality of vehicles Ma and Mb.

  In FIG. 1, for convenience, only two vehicles equipped with the vehicle-mounted device 1 are shown, but three or more vehicles may exist. Hereinafter, when distinguishing each vehicle-mounted device 1 mounted on the vehicles Ma and Mb, the vehicle-mounted device 1 mounted on the vehicle Ma is mounted on the vehicle-mounted device 1a and the vehicle-mounted device 1 mounted on the vehicle Mb is mounted on the vehicle. Also referred to as vessel 1b. Moreover, when distinguishing vehicle Ma, Mb clearly, it describes as the 1st vehicle Ma and the 2nd vehicle Mb. The vehicle-mounted device 1a corresponds to the direction estimating device recited in the claims, and the vehicle-mounted device 1b corresponds to the other device recited in the claims.

  When the GNSS satellites St1 to St3 are not distinguished, they are simply described as GNSS satellites. As for GNSS satellites, only three aircraft are shown in FIG. 1 for convenience, but there may be four or more. The GNSS satellite corresponds to the reference station described in the claims.

<Schematic Configuration of Direction Estimation System 100>
The GNSS satellites St1 to 3 are satellites used in a global navigation satellite system (GNSS). Each of the GNSS satellites St1 to St3 transmits radio waves including data (so-called ephemeris) indicating the current position of the satellite itself. In addition, the radio wave transmitted by each GNSS satellite St1 to 3 includes information indicating the time when the GNSS satellite transmits the radio wave. The signals transmitted from the GNSS satellites St1 to St3 are phase-modulated using a C / A code unique to each GNSS satellite. The C / A code corresponds to the transmission source information described in the claims.

  All of the GNSS satellites St1 to St3 exist at positions where the vehicles Ma and Mb can receive the radio wave transmitted from the GNSS satellite. In other words, the GNSS satellites St1 to St3 are all captured by the vehicles Ma and Mb. Note that a state where a vehicle can capture a certain GNSS satellite refers to a state where the vehicle can receive radio waves from the GNSS satellite.

  The vehicles Ma and Mb are vehicles that travel on the road. In the present embodiment, the vehicles Ma and Mb are four-wheeled vehicles, but are not limited thereto. Each vehicle may be a two-wheeled vehicle or a three-wheeled vehicle. A two-wheeled vehicle may include a motorbike.

  Each vehicle Ma, Mb has a function of receiving radio waves transmitted from the GNSS satellites St1 to St3. Each of the vehicles Ma and Mb is configured to perform wireless communication (so-called vehicle-to-vehicle communication) without using a wide-area communication network, using radio waves in a frequency band assigned in advance. The frequency band used for inter-vehicle communication may be designed as appropriate. For example, vehicle-to-vehicle communication may be realized using radio waves in the 760 MHz band. Of course, vehicle-to-vehicle communication may be realized using radio waves such as 2.4 GHz and 5.9 GHz bands.

  In each vehicle, the vehicle-mounted device 1 provides the function of receiving radio waves from the GNSS satellites St1 to St3 and the function of performing inter-vehicle communication. Hereinafter, the configuration of the vehicle-mounted device 1 mounted on each vehicle will be described in more detail.

<About the configuration of the vehicle-mounted device 1>
As shown in FIG. 2, the vehicle-mounted device 1 includes a control unit 11, a GNSS receiver 12, an inter-vehicle communication unit 13, a geomagnetic sensor 14, and a notification device 15. The control unit 11 is connected to each of the GNSS receiver 12, the inter-vehicle communication unit 13, the geomagnetic sensor 14, and the notification device 15 so as to be able to communicate with each other. For convenience, the vehicle on which the on-vehicle device 1 is mounted is distinguished from the vehicle on which the other on-vehicle device 1 is mounted, and is also referred to as the own vehicle.

  The control unit 11 is a unit that controls the overall operation of the vehicle-mounted device 1. The control unit 11 is configured as a normal computer, and includes a CPU 111, a RAM 112, a ROM 113, an I / O 114, a bus line connecting these configurations, and the like. The ROM 113 stores a program (hereinafter referred to as a control program) for causing a normal computer to function as the control unit 11.

  Note that the above-described control program only needs to be stored in a non-transitory tangible storage medium. Executing the control program by the CPU 111 corresponds to executing a method corresponding to the control program.

  In general, the control unit 11 is based on the data input from the GNSS receiver 12 or the inter-vehicle communication unit 13 and the direction in which another vehicle that performs inter-vehicle communication with the host vehicle exists. Is estimated. Details of the control unit 11 will be described later.

  The GNSS receiver 12 receives a radio wave transmitted from a GNSS satellite. When four or more GNSS satellites are captured, the GNSS receiver 12 acquires position information indicating the current position of the GNSS receiver 12 based on the radio wave received from each GNSS satellite. The current position of the GNSS receiver 12 may be represented by coordinates in a predetermined three-dimensional coordinate system adopted by GNSS, for example. Here, as an example, it is assumed that the current position of the GNSS receiver 12 is expressed in an ECEF (Earth Centered, Earth Fixed) coordinate system. The ECEF coordinate system is a three-dimensional coordinate system that rotates with the earth center from the origin. Of course, as another aspect, the current position of the GNSS satellite may be represented by a geodetic coordinate system using latitude, longitude, and altitude.

  The GNSS receiver 12 includes a pseudo-range identifying unit 121 that identifies a pseudo-range with a captured GNSS satellite (hereinafter, captured satellite) as a sub-function for identifying the current position. The pseudorange specifying unit 121 sequentially calculates the pseudorange with the GNSS satellite for each captured GNSS satellite based on the received radio wave.

  A known method may be used for the calculation method of the pseudo distance. For example, the pseudo distance specifying unit 121 multiplies the difference between the transmission time and the reception time of the received radio wave by the radio wave propagation speed C (C = 3 × 10 ^ 8 [m / sec]), and further divides the value by 2. What is necessary is just to employ | adopt as a pseudo distance. The transmission time is included in the received radio wave. The reception time may be specified by time information held by the GNSS receiver 12.

  Here, as an example, the pseudo distance specifying unit 121 calculates the pseudo distance by regarding the difference between the transmission time and the reception time as the flight time of radio waves (hereinafter, TOF: Time Of Flight). Not exclusively. The pseudo distance specifying unit 121 may specify the TOF based on the phase shift amount of the C / A code, or may specify the TOF by using other methods.

  The pseudorange specifying unit 121 sequentially provides the control unit 11 with data indicating the pseudorange for each specified captured satellite. The pseudo distance for each captured hygiene is provided to the control unit 11 in association with information (hereinafter, satellite identification information) indicating which GNSS satellite is the pseudo distance. The transmission source of the received radio wave, in other words, the captured satellite may be identified by the C / A code of the received radio wave. The GNSS receiver 12 corresponds to the receiver described in the claims. The acquisition satellite corresponds to the acquisition reference station described in the claims.

  The vehicle-to-vehicle communication unit 13 includes an antenna capable of transmitting and receiving radio waves in a frequency band used for vehicle-to-vehicle communication, and performs wireless communication directly with the other vehicle-mounted device 1 through the antenna. Specifically, the vehicle-to-vehicle communication unit 13 extracts data included in the received signal by performing predetermined processing such as analog-digital conversion, demodulation, and decoding on the signal received by the antenna, The extracted data is output to the control unit 11. In addition, an analog signal obtained by performing predetermined processing such as encoding, modulation, and digital / analog conversion on the data input from the control unit 11 is output to the antenna and radiated as a radio wave.

  The geomagnetic sensor 14 is a sensor for detecting the absolute direction of the host vehicle. As the geomagnetic sensor 14, for example, a three-axis geomagnetic sensor that detects (including estimation) the geomagnetism by decomposing it into three axial components orthogonal to each other can be employed. The detection result of the geomagnetic sensor 14 is sequentially provided to the control unit 11.

  The notification device 15 is a device for providing predetermined information to an occupant of the host vehicle. As the notification device 15, a display, an indicator, a speaker, or the like can be employed. The notification device 15 operates based on an instruction from the control unit 11 as described later.

<About the structure of the control unit 11>
Next, taking the control unit 11 of the vehicle-mounted device 1a mounted on the first vehicle Ma as an example, the configuration and operation of the control unit 11 will be described. The control unit 11 of the other vehicle-mounted device 1 has the same configuration.

  The control unit 11 provides various functions shown in FIG. 3 when the CPU 111 executes the above-described control program. Specifically, the control unit 11 includes, as functional blocks, an own vehicle single difference calculation unit F1, a transmission data generation unit F2, a transmission processing unit F3, a reception processing unit F4, another vehicle single difference identification unit F5, and a double difference calculation unit. F6, a coordinate information acquisition unit F7, a double difference change degree calculation unit F8, a virtual inclination calculation unit F9, a traveling direction specification unit F10, another vehicle direction estimation unit F11, and a notification processing unit F12.

  Part or all of the functional blocks included in the control unit 11 may be realized in hardware (in other words, as a circuit module) by one or a plurality of ICs.

  FIG. 3 illustrates an example in which only the double difference calculation unit F6, the coordinate information acquisition unit F7, the double difference change degree calculation unit F8, and the virtual inclination calculation unit F9 are connected to the RAM 112. The RAM 112 is configured to be able to communicate with other than the above-described functional blocks such as the reception processing unit F4. In addition, the RAM 112 stores a pseudorange for each captured satellite sequentially provided from the GNSS receiver 12.

  Based on the pseudoranges for each captured satellite stored in the RAM 112, the own vehicle single difference calculation unit F1 calculates, for each combination of two GNSS satellites, the difference between the pseudoranges of the GNSS satellites constituting the combination. Is calculated sequentially (for example, every 100 milliseconds). Hereinafter, a combination of two GNSS satellites as one set is also referred to as a satellite pair.

  For example, as shown in FIG. 1, when the first vehicle Ma captures three GNSS satellites GNSS satellites St1 to St3, a satellite pair composed of GNSS satellites St1 and St2, and a satellite pair composed of GNSS satellites St1 and St3. , Three satellite pairs of the satellite pair composed of the GNSS satellites St2 and St3 are established.

  In this case, the vehicle single difference calculation unit F1 calculates a single difference for each of the three satellite pairs. The single difference in the combination of the GNSS satellite St1 and the GNSS satellite St2 is the absolute value of the difference between the pseudorange with the GNSS satellite St1 and the pseudorange with the GNSS satellite St2.

  The single difference for each satellite pair sequentially calculated by the own vehicle single difference calculation unit F1 is stored in the RAM 112. The single difference stored in the RAM 112 is referred to by the double difference calculation unit F6. It is assumed that the single difference for each satellite pair is handled in association with information (hereinafter, pair information) indicating which satellite pair is the single difference.

  The own vehicle single difference calculation unit F1 corresponds to the self single difference calculation unit described in the claims. The single difference calculated by the own vehicle single difference calculation unit F1 corresponds to the self single difference described in the claims. The satellite pair corresponds to the reference station pair recited in the claims.

  The transmission data generation unit F2 is a functional block that generates a communication packet (hereinafter referred to as an inter-vehicle communication packet) to be transmitted to another vehicle by inter-vehicle communication. The transmission data generation unit F2 generates a captured satellite packet indicating a pseudo distance for each captured satellite stored in the RAM 112 as a vehicle-to-vehicle communication packet.

  In the captured satellite packet, the pseudo distance for each captured satellite is associated with the satellite identification information. Thereby, the other vehicle-mounted device 1 (for example, the vehicle-mounted device 1b) that has received the captured satellite packet determines the pseudo distance between the GNSS satellite captured by the first vehicle Ma and each captured satellite in the first vehicle Ma. Can be identified.

  The captured satellite packet includes a vehicle ID indicating the in-vehicle device 1 as a transmission source in addition to the pseudo distance and satellite identification information for each captured satellite. The vehicle ID is identification information assigned to each communication terminal (in other words, in-vehicle device) that performs inter-vehicle communication. The vehicle ID of the first vehicle Ma is included as a transmission source address in the captured satellite packet.

  Communication packets (for example, captured satellite packets) generated by the transmission data generation unit F2 are sequentially provided to the transmission processing unit F3. The transmission processing unit F3 outputs the communication packet input from the transmission data generation unit F2 to the vehicle-to-vehicle communication unit 13 for wireless transmission.

  FIG. 4 is a flowchart showing a procedure of processing (hereinafter referred to as transmission processing) executed by the transmission data generation unit F2 and the transmission processing unit F3 in order to transmit the captured satellite packet. The flowchart shown in FIG. 4 may be started sequentially (for example, every 10 milliseconds).

  First, in S1, the transmission data generation unit F2 determines whether or not a timer for transmitting captured satellite packets at a predetermined transmission cycle (hereinafter referred to as a transmission timer) has expired. The transmission timer is a timer that measures an elapsed time from the previous transmission of the captured satellite packet. The state in which the count value of the transmission timer becomes a value corresponding to the transmission cycle corresponds to the timer expiration state. The transmission timer is reset and restarted every time a captured satellite packet is transmitted. The transmission cycle may be designed as appropriate, for example, 100 milliseconds.

  In step S1, if the transmission timer has not yet expired, a negative determination is made and this flow ends. On the other hand, if the transmission timer has expired, an affirmative determination is made in step S1 and the process proceeds to step S2.

  In step S2, the transmission data generating unit F2 generates a captured satellite packet based on the pseudo distance (that is, captured hygiene information) for each captured satellite stored in the RAM 112, and provides the captured satellite packet to the transmission processing unit F3. Move. In step S3, the transmission processing unit F3 outputs the captured satellite packet provided from the transmission data generation unit F2 to the inter-vehicle communication unit 13 and wirelessly transmits it.

  The reception processing unit F4 acquires data received by the inter-vehicle communication unit 13. For example, the reception processing unit F4 acquires a captured satellite packet transmitted from another vehicle (for example, the second vehicle Mb). When receiving the captured satellite packet, the reception processing unit F4 provides the captured satellite packet to the other vehicle single difference identifying unit F5. Further, the captured satellite packet acquired by the reception processing unit F4 is stored in the RAM 112 while being distinguished for each vehicle that is the transmission source of the data. Note that the transmission source of the received data may be identified by the transmission source address included in the data.

  Based on the captured satellite packet of the other vehicle provided from the reception processing unit F4, the other-vehicle single-difference specifying unit F5 calculates a single-difference for each combination of GNSS satellites captured by the other vehicle. Calculation is performed in the same manner as in the part F1. That is, the other vehicle single difference identifying unit F5 identifies the single difference for each satellite pair in the other vehicle based on the captured satellite packet transmitted from the other vehicle.

  For example, the other vehicle single-difference specifying unit F5 calculates a single difference for each satellite pair for the second vehicle Mb based on the captured satellite packet received from the second vehicle Mb. When captured satellite packets are received from a plurality of other vehicles, a single difference is calculated for each satellite pair in which the GNSS satellites captured by the other vehicles are defined as a population.

  The single difference for each satellite pair in a certain other vehicle, which is calculated by the single vehicle single difference specifying unit F5, is stored in the RAM 112 while being distinguished for each vehicle. Hereinafter, for the sake of convenience, the single difference calculated by the own vehicle single difference calculating unit F1 is also referred to as the own vehicle single difference, and the single difference specified by the other vehicle single difference specifying unit F5 is also referred to as the other vehicle single difference. The other vehicle single difference specifying unit F5 corresponds to the other person single difference obtaining unit described in the claims, and the other vehicle single difference corresponding to the other single difference of the claims.

  Note that the single vehicle other difference is also stored in the RAM 112 in association with pair information indicating which satellite pair is the single difference, similar to the single vehicle single difference. It is preferable that the time stamp indicating the time when the data is stored is given to the data indicating the difference between the own vehicle and the other vehicle. The single vehicle difference for each other vehicle stored in the RAM 112 is referred to by the double difference calculation unit F6.

  Hereinafter, for simplification of description, the operation of each part will be described on the assumption that the first vehicle Ma performs inter-vehicle communication only with the second vehicle Mb. In addition, the first vehicle Ma has only three GNSS satellites GNSS satellites St1, St2, and St3 that are commonly captured by the second vehicle Mb.

  The double difference calculation unit F6 specifies a GNSS satellite (hereinafter, a common captured satellite) that is commonly captured by the first vehicle Ma and the second vehicle Mb. Then, the double difference D for each satellite pair that is established with the common captured satellite as a population is sequentially calculated (for example, every 100 milliseconds). The double difference D is the absolute value of the difference between the own vehicle single difference and the other vehicle single difference in the same satellite pair.

For example, the single difference of the first vehicle Ma in the satellite pair of the GNSS satellites St1 and St2 is d (a, St1, St2), and the single difference of the second vehicle Mb in the same satellite pair is d (b, St1, St2). Then, the double difference D (a, b, St1, St2) between the first vehicle Ma and the second vehicle Mb in the satellite pair of the GNSS satellites St1 and St2 is expressed by the following Equation 1. The own vehicle single difference and the other vehicle single difference in a certain satellite pair may be obtained by accessing the RAM 112.

By the way, the pseudo distance between the first vehicle Ma and the GNSS satellite St1 is Pd (a, St1), the pseudo distance between the first vehicle Ma and the GNSS satellite St2 is Pd (a, St2), and the second vehicle Mb and the GNSS satellite St1. And Pd (b, St2) as the pseudorange between the second vehicle Mb and the GNSS satellite St2, the double difference D (a, b, (St1, St2) can be expressed as the following Equation 2.

  The double difference D (a, b, St1, St2) with respect to the second vehicle Mb for the satellite pair composed of the GNSS satellites St1 and St2 obtained as described above is the difference between the first vehicle Ma and the second vehicle Mb. There is a correlation with the distance, and the closer the first vehicle Ma and the second vehicle Mb, the smaller the value. Further, when the first vehicle Ma and the second vehicle Mb are present at the same point, the double difference D (a, b, St1, St2) is zero. That is, the double difference D for each satellite pair that is common with the second vehicle Mb functions as an index of the distance between the first vehicle Ma and the second vehicle Mb.

Assuming that the number of captured satellites of each vehicle is 3 or less or that the almanac has not been acquired, the time information in each vehicle is asynchronous with respect to the reference time used in GNSS. Therefore, the pseudo distance in each vehicle includes an error derived from a time error. Here, Pd (a, St1), Pd (a, St2), and Pd (b, St1) Pd (b, St2) constituting the above formula 2 can be expressed more specifically by the following formulas 3 to 6: It is represented by

The parameters x ₁ , y ₁ , and z ₁ in Equations 3 to 6 are coordinates indicating the current position of the GNSS satellite St1 in the ECEF coordinate system, and the parameters x ₂ , y ₂ , and z ₂ are GNSS in the same coordinate system. This is a coordinate indicating the current position of the satellite St2. Parameters x _a , y _a , and z _a are coordinates that indicate the current position of the first vehicle Ma in the same coordinate system, and parameters x _b , y _b , and z _b are coordinates that indicate the current position of the second vehicle Mb. It is. t ₁ and t ₂ are time errors from the respective true values of the GNSS satellites St ₁ and St ₂ , and t _a and t _b are time errors from the respective true values of the first vehicle Ma and the second vehicle Mb. Show. The second term of each mathematical expression represents a component derived from a time error.

  Substituting Equations 3 to 6 into Equation 2 cancels time error components included in various pseudoranges. That is, in the double difference D obtained by the above method, the time error with respect to the reference time in each GNSS satellite and each vehicle is eliminated.

  In addition, since the distance between the first vehicle Ma and the second vehicle Mb is a distance (for example, within several hundreds of meters) at which vehicle-to-vehicle communication can be performed, an error in pseudo distance caused by the ionosphere and the troposphere is also common. It is offset against the GNSS satellite.

  That is, the double difference D calculated by the above method cancels the influence of various errors. As a result, the double difference D with respect to the second vehicle Mb functions as an index that indicates the distance between the first vehicle Ma and the second vehicle Mb with high accuracy.

  The double difference D for each satellite pair with respect to the second vehicle Mb calculated by the double difference calculation unit F6 as described above is stored in the RAM 112. The calculation results of the double difference calculation unit F6 at a plurality of time points may be stored side by side in chronological order so that the latest calculation result is the head for each satellite pair. For convenience, data in which the double difference D in a certain satellite pair is arranged in time series is referred to as time series data of the double difference D in the satellite pair.

  If there is a vehicle other than the second vehicle Mb within the range in which the first vehicle Ma can communicate between the vehicles, the other vehicles, like the second vehicle Mb, also have two satellites for each satellite pair. What is necessary is just to calculate the weight difference D. The double difference D for each satellite pair is calculated and stored separately for each other vehicle that is a communication partner for inter-vehicle communication. Note that data that has been stored for a certain period of time may be deleted as needed.

  The coordinate information acquisition unit F7 acquires coordinate information representing the current position of the captured satellite in the horizon orthogonal coordinate system (ENU: East, Noth, Up coordinate system). The ENU coordinate system is a coordinate system in which a predetermined representative point handled as the current position of the first vehicle Ma is the origin, the zenith direction is the Z axis, the east direction is the X axis, and the north direction is the Y axis. The representative point may be appropriately designed. For example, it may be an address described in the own vehicle Ma automobile storage location certificate or vehicle verification, or the origin of longitude and latitude of Japan (that is, 139 degrees 44 minutes 28 seconds 8869 east, 35 degrees north latitude). It may be set as a point of 39 minutes 29 seconds 1572).

  The coordinate information of each GNSS satellite may be acquired from an external server via a wide area communication network. Note that the ECEF coordinates may be converted into the ENU coordinates using a predetermined conversion matrix designed in advance by regarding an arbitrary representative point as the reception position. The ECEF coordinates of each GNSS satellite may be specified from information included in the ephemeris or almanac distributed from the GNSS satellite. The ephemeris and almanac may be acquired by various routes such as being provided from another vehicle by inter-vehicle communication. When the coordinate information acquisition unit F7 acquires the coordinate information, the coordinate information acquisition unit F7 stores the acquired coordinate information in the RAM 112.

  Based on the time-series data of the double difference D for each satellite pair, the double difference change degree calculating unit F8 calculates the degree of change (hereinafter referred to as change) α of the double difference D per unit time in the satellite pair. To do. FIG. 5 is a graph conceptually showing a time change of the double difference D in a certain satellite combination when the first vehicle Ma and the second vehicle Mb are in an approaching relationship.

  The horizontal axis of FIG. 5 represents time, and the vertical axis represents the value of the double difference D. A time Tnw provided on the horizontal axis represents a time point when the latest double difference D is calculated, and a time Tps represents a time point a certain time (ΔT in the figure) past from the time Tnw. Dnw represents the value of double difference D at time Tnw, and Dps is the value of double difference D at time Tps. In addition, the point in a graph represents the double difference calculated in each time.

  In such a case, for example, the double difference change degree calculation unit F8 calculates ΔD obtained by subtracting Dps from Dnw, and further divides ΔD by ΔT to identify the change degree α in the satellite combination. ΔT is an absolute value, and ΔD is a negative value when the double difference D tends to decrease. That is, when the double difference D tends to decrease, the sign of the degree of change α is negative.

  Therefore, the degree of change α functions as a parameter indicating whether or not the double difference D tends to decrease. The smaller the degree of change α, the sharper the double difference D decreases. Note that the alternate long and short dash line in FIG. 5 represents a linear function that approximates the relationship between the elapsed time and the double difference D, with the double difference D within a fixed period of time from the present as a population.

  Incidentally, the double difference D for the second vehicle Mb is proportional to the distance between the first vehicle Ma and the second vehicle Mb as described above. Therefore, the negative change α of the double difference D for the second vehicle Mb means that the distance between the first vehicle Ma and the second vehicle Mb is decreasing.

The virtual inclination calculation unit F9 calculates the virtual inclination β in the satellite pair by using the coordinates indicating the current positions of the two GNSS satellites constituting the predetermined satellite pair and the following equation (7).

The parameters e _m , n _m , and u _m in Equation 7 are parameters indicating the current position in the ENU coordinate system of one of the two GNSS satellites constituting the satellite combination, and the parameters e _n , n _n , u _n is a parameter indicating the current position of the other GNSS satellite. That is, the virtual position when the current position of one of the two GNSS satellites constituting the satellite combination is (e _m , n _m , u _m ) and the other current position is (e _n , n _n , u _n ). The slope β is determined by Equation 7 above.

  The coordinate information indicating the current position of each GNSS satellite in the ENU coordinate system is acquired by the coordinate information acquisition unit F7 described above. Note that the coordinate information acquired by the coordinate information acquisition unit F7 is strictly a coordinate with a point different from the current position of the first vehicle Ma as the origin, but the distance between the representative point and the first vehicle Ma is GNSS. Since the value is sufficiently smaller than the distance between the satellite and the representative point, it can be handled as an error. In the simulation, even if coordinate information with an arbitrary point in Japan as the origin is used, a virtual inclination β substantially the same as that when using coordinate information with the specific position of the first vehicle Ma as the origin is obtained. I have confirmed that. The range including substantially the same here is a range in which there is no problem in estimating the direction in which the second vehicle Mb exists from the virtual inclination β by a method described later.

  When a point where the double difference D in a certain satellite pair is zero is projected onto the XY plane (in other words, the ground plane) of the ENU coordinate system, the set of points is a linear function having a predetermined inclination. (Hereinafter, double difference zero straight line). The virtual slope β determined by Equation 7 corresponds to the slope of this linear function. The technical significance of the virtual inclination β calculated by the virtual inclination calculation unit F9 will be described later. Since the satellite coordinates are represented by the ENU coordinate system, the positive direction of the X axis constituting the XY plane corresponds to the east, and the positive direction of the Y axis corresponds to the north. The virtual inclination calculation unit F9 corresponds to the β calculation unit described in the claims, and the virtual inclination β corresponds to the parameter β.

  Based on the detection result of the geomagnetic sensor 14, the traveling direction identification unit F10 identifies the direction (that is, the traveling direction) that the host vehicle is facing north. The identification result of the traveling direction identification unit F10 is provided to the other vehicle direction estimation unit F11. In the present embodiment, as an example, the geomagnetic sensor 14 is used to specify the traveling direction of the host vehicle, but the present invention is not limited thereto. As another embodiment, the traveling direction may be specified using a gyro sensor. The traveling direction specifying unit F10 corresponds to the traveling direction acquisition unit recited in the claims.

  The other vehicle azimuth estimation unit F11 is based on the virtual inclination β calculated by the virtual inclination calculation unit F9 and the traveling direction specified by the traveling direction specifying unit F10, in which the second vehicle Mb exists as viewed from the host vehicle ( Thereafter, the other vehicle direction) is estimated.

  Here, the correspondence relationship between the virtual inclination β for each satellite pair and the direction in which the second vehicle Mb as the other vehicle exists will be described with reference to FIG. FIG. 6 represents a zero-double difference line for each satellite pair that is established with a GNSS satellite that is commonly captured by the first vehicle Ma and the second vehicle Mb as a population. A double difference zero straight line in a certain satellite pair is a set of points obtained by projecting on the XY plane (in other words, the ground plane) of the ENU coordinate system the point where the double difference D in the satellite pair becomes 0 as described above. It corresponds to.

  Specifically, a straight line L (St1, St2) indicated by a solid line represents a double difference zero straight line in a satellite pair composed of GNSS satellites St1 and St2. A straight line L (St1, St3) indicated by a one-dot chain line represents a double difference zero straight line in a satellite pair composed of the GNSS satellites St1 and St3, and a straight line L (St2, St3) indicated by a two-dot chain line is a GNSS satellite St2. And a double difference zero straight line in the satellite pair consisting of St3 and St3. The virtual inclination β as the inclination of various double difference zero straight lines is obtained by Expression 7.

  The inventors perform simulations assuming various satellite coordinates and vehicle positional relationships, and analyze the results, so that the absolute value is the smallest among the satellite pairs in which the degree of change α is negative. It has been found that there is a correlation between the virtual inclination β of the satellite pair (hereinafter referred to as the minimum decrease pair) and the direction in which the second vehicle Mb exists as seen from the host vehicle.

  For example, when the traveling direction of the host vehicle is relatively northward, the direction in which the Y coordinate is positive out of the two directions in which the double difference zero straight line corresponding to the minimum decrease pair extends from the origin. It is highly possible that the second vehicle Mb exists in the vehicle, and when the traveling direction of the host vehicle is relatively southward, there is a high possibility that the second vehicle Mb exists in a direction in which the Y coordinate is negative. Naturally, since the direction in which the double difference zero straight line extends is defined by the virtual inclination β, the virtual inclination β of the minimum decrease pair functions as an indicator of the direction in which the second vehicle Mb exists. The other vehicle orientation estimation unit F11 estimates the other vehicle orientation based on the above knowledge. The other vehicle direction estimation unit F11 corresponds to the other device direction estimation unit described in the claims.

  The notification processing unit F12 performs a process for notifying the driver of the estimation result by the other vehicle direction estimation unit F11. For example, when the vehicle-mounted device 1 includes a display as the notification device 15, the notification processing unit F12 displays an image indicating the direction in which the second vehicle Mb is present on the display. In addition, when the vehicle-mounted device 1 includes a speaker as the notification device 15, the notification processing unit F12 notifies the driver of the direction in which the second vehicle Mb exists by outputting a predetermined message from the speaker. May be. The display used for notification may be a head-up display.

<Other vehicle direction estimation processing>
Next, the other vehicle orientation estimation process performed by the control unit 11 will be described using the flowchart shown in FIG. This other vehicle direction estimation process corresponds to a process of estimating the direction in which another vehicle (here, the second vehicle Mb) existing around the first vehicle Ma as the own vehicle exists. Here, the vicinity of the first vehicle Ma corresponds to a range in which the first vehicle Ma can communicate between vehicles.

  The flowchart shown in FIG. 7 may be started when the captured satellite data from the second vehicle Mb is received.

  First, in step S10, the reception processing unit F4 stores the received captured satellite data in the RAM 112, and proceeds to step S20. In step S20, the other vehicle single difference specifying unit F5 refers to the RAM 112, calculates the other vehicle single difference for each satellite pair for the second vehicle Mb, and proceeds to step S30.

  In step S30, the double difference calculation unit F6 reads the captured satellite data of the host vehicle stored in the RAM 112, and proceeds to step S40. In step S40, the double difference calculation unit F6 specifies a GNSS satellite (that is, a common captured satellite) that the host vehicle and the second vehicle Mb are capturing in common, and proceeds to step S50.

  In step S50, the double difference calculation unit F6 determines whether or not the number N of commonly acquired satellites is 3 or more. Here, when the number N of commonly acquired satellites is 3 or more, an affirmative determination is made in step S50, and the process proceeds to step S60. On the other hand, if the number N of commonly captured satellites is less than 3, a negative determination is made in step S50 and this flow is terminated.

  In step S60, the double difference calculation unit F6 selects any two captured satellites from the three or more common captured satellites, and proceeds to step S70. In step S70, the double difference calculation unit F6 calculates the double difference D for the satellite pair composed of the selected two captured satellites, and proceeds to step S80.

  In step S80, it is determined whether or not the double difference D has been calculated for all the satellite pairs that can be established with the common captured satellite specified in step S40 as a population. If a satellite pair for which the double difference D has not yet been calculated remains, the process returns to step S60, selects a satellite pair for which the double difference D has not been calculated, and proceeds to step S70. That is, by repeating Step S60 to Step S80, the double difference D is calculated for all the satellite pairs in which the GNSS satellites commonly captured by the first vehicle Ma and the second vehicle Mb are determined as a population.

  If the double difference D is calculated for all the satellite pairs, an affirmative determination is made in step S80 and the process proceeds to step S90. The calculated double difference D for each satellite pair is stored in the RAM 112 in association with pair information indicating which satellite pair is the double difference D and a time stamp indicating the calculation time. As a result, the RAM 112 accumulates the double difference D for each satellite pair.

  In step S90, the double difference change degree calculation unit F8 calculates the change degree α of the double difference D for each satellite pair based on the time series data of the double difference D for each satellite pair stored in the RAM 112. Then, the process proceeds to step S100. If a sufficient number of double differences D for calculating the degree of change α has not yet been accumulated in the RAM 112, this flow may be terminated.

  FIG. 8 is a graph conceptually showing the degree of change α for each satellite pair. D (St1, St2) in the figure represents an approximate straight line of the double difference D in the combination of the GNSS satellites St1 and St2. As described above, the inclination of the approximate straight line represents the degree of change α in the combination of the GNSS satellites St1 and St2. In the figure, D (St1, St3) is an approximate straight line of the double difference D in the combination of the GNSS satellites St1 and St3, and D (St2, St3) is an approximation of the double difference D in the combination of the GNSS satellites St2 and St3. Each represents a straight line. FIG. 8 shows that the change α in the satellite pair of the GNSS satellites St1 and St2 is the smallest value among the change α of all the satellite pairs. That is, the satellite pair of the GNSS satellites St1 and St2 corresponds to the minimum decrease pair. Hereinafter, as an example, it is assumed that the satellite pair of the GNSS satellites St1 and St2 is the minimum decrease pair.

  In step S100, the virtual inclination calculation unit F9 selects the decrease degree minimum pair, and proceeds to step S110. In step S110, the virtual inclination calculation unit F9 calculates the virtual inclination β of the minimum reduction pair using the coordinate information indicating the current positions of the two GNSS satellites constituting the minimum reduction pair and Equation 7 above. The process moves to step S120.

  In step S120, the other vehicle direction estimation unit F11 determines the direction in which the second vehicle Mb exists (hereinafter, based on the virtual inclination β calculated by the virtual inclination calculation unit F9 and the traveling direction specified by the traveling direction specifying unit F10). , Other vehicle direction).

  Specifically, when the traveling direction of the host vehicle is relatively northward, the double difference determined by the virtual slope β of the minimum decrease pair in the region where the Y axis is positive in the XY plane. It is estimated that the second vehicle Mb exists in the direction in which the zero straight line extends from the origin. Note that the positive Y-axis direction of the XY plane represents the north, and the positive X-axis direction represents the east. If the traveling direction of the host vehicle is relatively northward and the virtual inclination β is −1, it is estimated that the second vehicle Mb exists in the northwest direction.

  When the traveling direction of the host vehicle is relatively southward, the zero-double difference line determined by the virtual inclination β of the minimum decrease pair in the region where the Y axis is negative in the XY plane is the origin. It is determined that the second vehicle Mb exists in the direction extending from the vehicle. If the traveling direction of the host vehicle is relatively southward and the virtual inclination β is −1, it is estimated that the second vehicle Mb exists in the southeast direction.

  That is, the other vehicle azimuth estimation unit F11 converts the virtual inclination β of the minimum decrease pair into an azimuth according to the value depending on whether the traveling direction of the host vehicle is north or south, and proceeds to step S130. . In step S130, the notification processing unit F12 notifies the driver of the estimation result in step S120 and ends this flow.

<Summary of Embodiment>
In the above configuration, the control unit 11 sequentially calculates the double difference D for each satellite pair in the first vehicle Ma as the own vehicle and the second vehicle Mb as the other vehicle, and the degree of change α is negative. The satellite pair having the smallest absolute value among the existing satellite pairs (that is, the minimum decrease pair) is determined. Then, an azimuth determined from the virtual inclination β calculated using the coordinate information of the decrease degree minimum pair and the traveling direction of the host vehicle is regarded as the azimuth in which the second vehicle Mb exists.

  It can be confirmed by numerical analysis that there is a correspondence relationship between the virtual inclination β calculated using the coordinate information of the minimum decrease pair, the traveling direction of the host vehicle, and the direction in which the second vehicle Mb exists. ing. Therefore, according to the above configuration, the azimuth in which the second vehicle Mb exists can be estimated from the virtual inclination β calculated using the coordinate information of the decrease degree minimum pair and the traveling direction of the host vehicle.

  In determining the minimum decrease pair, the first vehicle Ma and the second vehicle Mb only need to capture three GNSS satellites in common. Therefore, even when the number of captured satellites of at least one of the first vehicle Ma and the second vehicle Mb is 3, the direction in which the second vehicle Mb exists can be estimated.

  Further, it is not necessary to perform positioning calculation in estimating the direction of the other vehicle. Therefore, the direction in which the other vehicle exists can be estimated without performing the positioning calculation.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, The various modifications described below are also contained in the technical scope of this invention, and also in addition to the following However, various modifications can be made without departing from the scope of the invention.

  In addition, about the member which has the same function as the member described in the above-mentioned embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted. In addition, when only a part of the configuration is mentioned, the configuration of the above-described embodiment can be applied to the other portions.

[Modification 1]
In the above-described embodiment, the aspect in which the azimuth is estimated using the virtual inclination β of only the minimum decrease pair among various satellite pairs is illustrated, but the present invention is not limited thereto. For example, among the satellite pairs having a negative change rate α, all the satellite pairs whose absolute values are equal to or less than a predetermined threshold are selected, and the average value of the virtual inclinations β of the selected satellite pairs is calculated as the second value. You may employ | adopt as an azimuth | direction in which the vehicle Mb exists.

  Further, for example, among the satellite pairs having a negative degree of change α, the satellite pair having the smallest absolute value to the kth smallest satellite pair is selected, and the virtual inclination β of the selected k satellite pairs is selected. May be adopted as the direction in which the second vehicle Mb exists. k is a positive integer value designed as appropriate, and may be 2 or 3, for example.

  When estimating the direction in which the second vehicle Mb exists from the virtual inclination β of a plurality of satellite pairs, a weight corresponding to the degree of change α is given to the virtual inclination β instead of a simple average of the plurality of virtual inclinations β. A value calculated by weighted average may be adopted as the direction in which the second vehicle Mb exists. The weight used for the weighted average is increased as the absolute value of the degree of change α is smaller.

[Modification 2]
In the above description, the captured satellite data is exemplified as data indicating the pseudorange for each captured satellite. However, the present invention is not limited to this. Each onboard equipment 1 is good also as an aspect which transmits the data which matched the single difference for every satellite pair which the own vehicle single difference calculation part F1 calculated as paired satellite data with pair information.

  Even in such an aspect, the on-vehicle device 1 on the receiving side can specify a self-single difference for another vehicle (in other words, another single-vehicle difference for the own vehicle).

[Modification 3]
In the above, the aspect in which the direction estimation device according to the claims is mounted on the vehicle as the vehicle-mounted device 1 is exemplified, but the present invention is not limited thereto. In other words, the mobile body to which the direction estimation device according to the claims is applied is not limited to a vehicle.

  For example, the mobile body to which the direction estimation device according to the claims is applied may be a pedestrian, a bicycle (hereinafter referred to as a pedestrian) or the like. In that case, what is necessary is just to make a portable terminal (for example, smart phone) which a pedestrian carries function as a direction estimation apparatus. The mobile terminal that functions as the direction estimation device may have a function corresponding to the control unit 11, the GNSS receiver 12, and the inter-vehicle communication unit 13.

  Note that the communication mode for transmitting and receiving captured satellite data between various devices is not limited to inter-vehicle communication. Devices that exist within a certain range (for example, within several hundreds of meters) need only be able to perform wireless communication directly or indirectly. For example, Bluetooth (registered trademark) can be adopted as the communication standard. Note that indirect communication between devices refers to a mode in which devices perform wireless communication via a communication terminal (a so-called roadside device) or a wide area communication network provided along a road.

[Modification 4]
It is not necessary for all moving bodies to have all the functions of the on-vehicle device 1 described above. For example, even if a pedestrian or the like has a function of transmitting captured satellite data, a device that does not have a function of receiving pseudo-distance related information transmitted from another mobile body (hereinafter, a transmission device) is used. good. The transmission device limited to the transmission function as described above can be realized at a lower cost than the vehicle-mounted device 1 described above. Therefore, introduction of the transmission device to a pedestrian or the like can be promoted.

[Modification 5]
Even if the transmission device referred to in Modification 4 captures four or more GNSS satellites, the information shown in the captured satellite data is limited to the pseudo-range for the predetermined three GNSS satellites. It is preferable. This is due to the following reason.

  If the pseudoranges for the four GNSS satellites are disclosed, the position of the transmission source may be evaluated by the receiving side. On the other hand, when the transmission device reduces the number of GNSS satellites that transmit pseudoranges to three, other devices cannot evaluate the absolute position of the transmission device. That is, according to the configuration of the fifth modification, the privacy of the user who uses the transmission device can be protected.

  Note that the three GNSS satellites that disclose the pseudoranges in the captured satellite data may be three aircraft with relatively good signal quality such as received signal strength and SN ratio. This is because the GNSS satellite with good signal quality is highly likely to be captured by the vehicle-mounted device 1 existing in the vicinity.

  Of course, as described in the second modification, the captured satellite packet transmitted by the transmission device 2 may be information indicating a single difference for each satellite pair whose population is a predetermined three GNSS satellites.

[Modification 6]
Other devices (hereinafter referred to as other devices) that are communication partners of the direction estimating device such as the vehicle-mounted device 1 are not limited to devices that are used in moving objects, but other devices are fixed terminals that are fixed along roads and the like. There may be.

[Modification 7]
In the above, although the aspect which uses a GNSS satellite as a reference station as described in a claim was illustrated, it is not restricted to this. The reference station described in the claims is not limited as long as the direction estimation device can identify the distance from the reference station, and may be, for example, a radio base station (for example, a base station of a mobile phone) that constructs a public radio communication network. .

100 direction estimation system, Ma / Mb vehicle, St1, St2, St3 GNSS satellite (reference station), 1.1a / 1b on-board unit, 11 control unit, 12 GNSS receiver (receiver), 13 inter-vehicle communication unit, 14 geomagnetism Sensor, 15 Informing device, 111 CPU, 112 RAM, 113 ROM, 114 I / O, 121 Pseudo distance specifying unit, F1 Vehicle single difference calculation unit (self single difference calculation unit), F2 transmission data generation unit, F3 transmission processing Unit, F4 reception processing unit, F5 other vehicle single difference identification unit (other single difference difference acquisition unit), F6 double difference calculation unit, F7 coordinate information acquisition unit, F8 double difference change degree calculation unit, F9 virtual inclination calculation unit (Β calculation unit), F10 traveling direction specifying unit, F11 other vehicle direction estimation unit (other device direction estimation unit), F12 notification processing unit

Claims (4)

Used in mobiles,
A receiver (12) that receives radio waves that are transmitted from a plurality of reference stations that exist at different positions and that includes transmission source information indicating the transmission source of the radio waves;
A pseudo distance specifying unit that sequentially specifies a pseudo distance with a capture reference station that is the reference station that is capable of receiving the radio wave among a plurality of the reference stations, based on the radio wave from the capture reference station received by the receiver ( 121),
When there are three or more acquisition reference stations, each of at least two or more sets of reference station pairs that are formed with two acquisition reference stations as one set, the pseudo distance of the two acquisition reference stations constituting the reference station pair. A self-single difference calculation unit (F1) that sequentially calculates a self-single difference that is an absolute value of the difference;
Another person single difference acquisition unit (F5) for acquiring another single difference corresponding to the self single difference for each reference station pair for another device;
For each reference station pair, a double difference calculation unit (F6) that calculates a double difference that is a difference between the self-single difference and the other single difference corresponding to the reference station pair;
For each reference station pair, a double difference change degree calculation unit (F8) that calculates a change degree indicating a change degree per unit time of the double difference;
Among the reference station pairs in which the degree of change is negative, the current position in the horizon orthogonal coordinate system of the two reference stations constituting the minimum decrease pair that is the reference station pair whose absolute value is the minimum A coordinate information acquisition unit (F7) for acquiring coordinates to be represented;
A β calculation unit (F9) for calculating a parameter β determined by substituting coordinate information indicating the position of the minimum degree of decrease into the following equation;
A traveling direction acquisition unit (F10) that acquires a traveling direction of the moving body;
And an other device direction estimating unit (F11) for estimating an azimuth in which the other device exists based on the parameter β calculated by the β calculating unit and the traveling direction of the moving body. Direction estimation device.

(The parameters e _m , n _m , and u _m in the above formula are parameters representing the position in one horizon orthogonal coordinate system of the two reference stations constituting the minimum decrease pair, and the parameters e _n , n _n, u _n is a parameter representing the other position of the reference station in the horizon orthogonal coordinate system) In claim 1,
The other device direction estimation unit identifies a direction corresponding to the value of the parameter β based on a traveling direction of the moving body, and estimates that the other device exists in the specified direction. apparatus. In claim 1,
The β calculating unit selects, from among the plurality of reference station pairs, the smallest change degree to the kth smallest one, and calculates the parameter β for each of the selected plurality of reference station pairs,
The other apparatus direction estimation unit specifies an azimuth corresponding to an average or a weighted average of a plurality of the parameters β based on a traveling direction of the moving body, and estimates that the other apparatus exists in the specified azimuth. A characteristic direction estimation device. In any one of Claims 1-3,
The direction estimation apparatus according to claim 1, wherein the reference station is a satellite used in a global navigation satellite system.

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