JP2005227066A - Navigation system and azimuth detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a navigation system and an azimuth detection method capable of detecting the azimuth of own vehicle correctly even at the time when the own vehicle is stopping, running toward backward, or existing in such a place where the magnetic field is disturbed. <P>SOLUTION: The GPS satellite 50a is positioned by modifying the directional pattern of the GPS antenna 5, so that the azimuth of an own vehicle 40 may be detected by the modified angle AntΔθ of the directional pattern of the GPS antenna 5 obtained when the GPS antenna 5 received the radio wave from the GPS satellite 50a, and the azimuth Aθ of the GPS satellite 50a obtained by the received radio wave of the GPS satellite 50a. Thereby, the azimuth of the own vehicle 40 can be detected without running the own vehicle 40, i.e. the azimuth of the own vehicle 40 is made to be able to detect correctly. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a navigation device and a direction detection method, and more particularly, to a direction detection method for detecting the direction of a host vehicle.

  In general, an in-vehicle navigation device that provides driving guidance for a host vehicle so that a driver can easily reach a desired destination by using a self-contained navigation sensor, a GPS (Global Positioning System) receiver, or the like. Is read from a recording medium such as a DVD-ROM or a hard disk and displayed on the screen together with a vehicle position mark indicating the current position of the host vehicle.

  Here, the self-contained navigation sensor includes a relative azimuth sensor (for example, a gyro sensor) that detects the rotation angle of the vehicle, and a distance sensor that outputs one pulse every time the vehicle travels a predetermined distance. In the navigation device, a change in direction due to movement of the host vehicle is detected by a relative position sensor, and a vehicle position mark specifying the direction of the host vehicle is displayed on the screen.

  The GPS receiver obtains the orbit information of the GPS satellites and the propagation time information of the radio waves by receiving radio waves sent from a plurality of GPS satellites, and acquires the position information of the own vehicle based on this information. Yes. In the navigation device, the position information of the host vehicle is input from the GPS receiver, and the current position of the host vehicle and the position of the host vehicle before one sampling time ΔT are changed according to the change in the position of the host vehicle due to the movement of the vehicle. Based on this, the direction of the host vehicle is detected, and a vehicle position mark specifying the direction of the host vehicle is displayed on the screen.

  Further, in the navigation device, by moving the vehicle position mark on the map data according to the movement of the host vehicle, or by fixing the vehicle position mark at a predetermined position on the screen and scrolling the map data in the vicinity thereof, You can see at a glance where your vehicle is currently traveling and in which direction the vehicle is facing.

Further, a plurality of azimuth detecting means, for example, a GPS receiver, a geomagnetic sensor for detecting geomagnetism, a left and right wheel sensor for detecting a difference in rotational speed between the left and right wheels of the vehicle front wheel, and a steering sensor for detecting a steering angle are used. There is a technique for estimating the direction of a vehicle (for example, Patent Document 1).
JP-A-6-66577

  However, in the conventional navigation device including Patent Document 1, the vehicle is allowed to travel a predetermined distance except for the geomagnetic sensor, and the direction of the vehicle is detected on the assumption that the traveling direction is the front direction of the vehicle. Therefore, when the host vehicle is driven in the back direction when the host vehicle is parked at the parking lot, the traveling direction of the host vehicle is erroneously determined, and the direction of the host vehicle cannot be accurately detected. There was a problem. In addition, when the traveling direction of the host vehicle is erroneously determined, if the host vehicle is stopped, there is a problem that an accurate direction of the host vehicle cannot be newly detected. Further, when a geomagnetic sensor is used, there is a problem that the direction of the host vehicle cannot be accurately detected in a place where the magnetic field is disturbed.

  The present invention has been made to solve such a problem, and an object of the present invention is to detect the direction of the host vehicle even when the host vehicle is stopped. It is another object of the present invention to accurately detect the azimuth of the host vehicle even when the host vehicle is traveling in the back direction or is present in a place where the magnetic field is disturbed.

  In order to solve the above problems, in the navigation device of the present invention, the GPS antenna directivity pattern is changed by changing the directivity pattern of the GPS antenna, and the change in the directivity pattern of the GPS antenna obtained when the GPS satellite is captured. The direction of the host vehicle is calculated based on the angle and the direction of the GPS satellite.

  According to the present invention configured as described above, the direction of the host vehicle is detected based on the change angle of the directivity pattern of the GPS antenna obtained without traveling the host vehicle and the direction of the GPS satellite. Even when the vehicle is stopped, it is possible to detect the direction of the host vehicle, and even if the host vehicle is traveling in the back direction or is present in a place where the magnetic field is disturbed, The direction can be accurately detected. Therefore, the user can always grasp the exact direction of the host vehicle.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration example of the navigation device according to the present embodiment. In FIG. 1, reference numeral 1 denotes a navigation device. Reference numeral 2 denotes a DVD-ROM which stores various types of map data necessary for map display and route search. Here, the DVD-ROM 2 is used as a recording medium for storing the map data, but other recording media such as a CD-ROM and a hard disk may be used.

  A map data reading unit 3 reads map data from the DVD-ROM 2. Reference numeral 4 denotes an operation unit, which includes, for example, a remote controller (remote controller) or a touch panel. The operation unit 4 allows the user to set various information (for example, a route guidance destination) for the navigation device 1 and various operations (for example, screen scrolling, numerical value input, route search instruction, etc.). Used to do things.

  A GPS antenna 5 receives a radio wave transmitted from a GPS satellite and outputs it as a GPS signal. Here, the GPS signal includes GPS satellite orbit information and radio wave propagation time information. The GPS antenna 5 is an antenna that can change the angle of the directivity pattern, for example, a smart antenna (adaptive array antenna) that can direct directivity in a desired direction.

  Reference numeral 6 denotes a GPS satellite azimuth detection unit, which performs two-dimensional positioning processing or three-dimensional positioning processing based on the GPS signal input from the GPS antenna 5, and calculates the position of the host vehicle and the direction of the GPS satellite. Further, the GPS satellite azimuth detecting unit 6 includes a buffer for temporarily storing the azimuth information of the GPS satellite which is the calculation result.

  Here, when two-dimensional positioning is used, the GPS antenna 5 receives radio waves transmitted from three GPS satellites and outputs respective GPS signals. Then, the GPS satellite azimuth detecting unit 6 inputs each GPS signal from the GPS antenna 5 and determines the absolute position of the host vehicle based on the orbit information and the radio wave propagation time information of each GPS satellite obtained from these GPS signals. calculate. Here, if the timepiece mounted on the host vehicle is accurate, the absolute position of the host vehicle can be calculated from the GPS signals from the two GPS satellites. However, since the clock mounted on the host vehicle is inaccurate, it is necessary to receive radio waves from three GPS satellites having an accurate atomic clock.

  In the GPS satellite azimuth detecting unit 6, for example, each GPS satellite is calculated by calculating the absolute position of each GPS satellite from the orbit information of each GPS satellite and multiplying the propagation time of the radio wave from each GPS satellite to the host vehicle and the speed of light. Calculate the distance from the vehicle to your vehicle. Then, the absolute position of the host vehicle is obtained based on the absolute position information of each GPS satellite and the distance information from each GPS satellite to the host vehicle. Further, the GPS satellite direction detection unit 6 is selected based on a predetermined condition (for example, a condition that the intensity of the radio wave received by the GPS antenna 5 is the strongest) among the absolute position of the own vehicle and the three GPS satellites. The direction of the selected GPS satellite is obtained based on the absolute position of the single GPS satellite.

  Further, when using the three-dimensional positioning, the GPS satellite direction detection unit 6 obtains the absolute position of the host vehicle and the direction of the GPS satellite using four GPS satellites.

  Reference numeral 7 denotes an antenna control unit that electrically rotates the directivity pattern of the GPS antenna 5 by a predetermined angle by 360 ° with respect to a direction (for example, forward direction) specified in the host vehicle.

  Reference numeral 8 denotes an antenna direction detection unit that examines the intensity of the radio wave received by the GPS antenna 5 at each angle of the directivity pattern of the GPS antenna 5. The antenna direction detection unit 8 includes a buffer, extracts the rotation angle information of the directivity pattern when the intensity of the radio wave received by the GPS antenna 5 is the strongest, and temporarily stores it. Furthermore, the antenna direction detection unit 8 outputs a control signal to the GPS satellite direction detection unit 6 when the intensity of the radio wave received by the GPS antenna 5 is higher than the intensity when it was stored in the previous buffer.

  For example, the antenna direction detection unit 8 extracts the rotation angle information of the directivity pattern when the radio wave is received by the GPS antenna 5 from the antenna control unit 7 and stores it in the buffer, and the intensity of the received radio wave becomes stronger than before. If so, the rotation angle information of the directivity pattern at that time is updated and stored in the buffer. Thereby, the rotation angle information when the intensity of the received radio wave is strongest can be stored in the buffer. Then, when the stored contents of the buffer are updated, a control signal is output to the GPS satellite azimuth detecting unit 6. The GPS satellite azimuth detection unit 6 updates and stores GPS satellite azimuth information when a control signal is input in a buffer.

  Reference numeral 9 denotes a vehicle azimuth calculation unit which inputs GPS satellite azimuth information stored in the buffer of the GPS satellite azimuth detection unit 6 and rotates the rotation angle of the directivity pattern stored in the buffer of the antenna direction detection unit 8. Input information (direction of GPS satellites as seen from own vehicle). Then, the direction of the host vehicle is calculated based on the direction of the GPS satellite and the rotation angle of the directivity pattern. Reference numeral 10 denotes a GPS receiver, which includes a GPS satellite orientation detection unit 6, an antenna control unit 7, an antenna direction detection unit 8, and a vehicle orientation calculation unit 9.

  11 is a map buffer for temporarily storing map data read from the DVD-ROM 2 by the map data reading unit 3. Reference numeral 12 denotes a map reading control unit, which controls when the map data reading unit 3 reads map data from the DVD-ROM 2. When the screen center position is calculated by the map reading control unit 12, a map data reading instruction including a predetermined range including the screen center position is sent from the map reading control unit 12 to the map data reading unit 3 to display the map display and the guide route. The map data necessary for the search is read from the DVD-ROM 2 and stored in the map buffer 11.

  A map drawing unit 13 generates map image data necessary for display on the display device 26 described later, based on the map data stored in the map buffer 11. Reference numeral 14 denotes a VRAM (video RAM), which temporarily stores the map image data generated by the map drawing unit 13. A reading control unit 15 controls reading of map image data from the VRAM 14. The map image data generated by the map drawing unit 13 is temporarily stored in the VRAM 14, and the map image data for one screen is read by the read control unit 15.

  Reference numeral 16 denotes an operation control unit that gives instructions to each unit in the navigation device 1 in accordance with an operation performed on the operation unit 4. Reference numeral 17 denotes an operation screen generation unit that generates and outputs an operation screen necessary for performing various operations using the operation unit 4. Reference numeral 18 denotes various mark generation units that generate and output a vehicle position mark displayed at the position of the host vehicle after the map matching processing, various landmarks displaying a parking lot, a gas station, a convenience store, and the like. .

  Reference numeral 19 denotes a data storage unit which inputs and sequentially stores the position information of the host vehicle output from the GPS satellite heading detection unit 6 and the heading information of the host vehicle output from the vehicle heading calculation unit 9. Reference numeral 21 denotes a map matching control unit, which uses the map data read to the map buffer 11 and the position information and direction information of the host vehicle stored in the data storage unit 19 to project each vehicle travel distance. A map matching process is performed to correct the position of the vehicle on the road of the map data.

  Reference numeral 22 denotes a guidance route control unit, which searches for a guidance route with the lowest cost connecting the current location to the destination by using the map data stored in the map buffer 11. For example, a guidance route that minimizes the cost under various conditions such as the shortest time, the shortest distance, and general road priority is searched. As a typical method of route search, a depth-first search (DFS) method, a breadth-first search (BFS) method, and a Dijkstra method, which is a kind of breadth-first search, are known. A guidance route memory 23 stores guidance route data (a set of nodes from the current location to the destination) set by the guidance route control unit 22.

  A guidance route drawing unit 24 generates drawing data for the guidance route using the result of the route search process stored in the guidance route memory 23. That is, from the guidance route data stored in the guidance route memory 23, the one included in the map area drawn in the VRAM 14 at that time is selectively read out, and is superimposed on the map image in a predetermined color different from other roads. Draws a boldly emphasized guide route.

  An image composition unit 25 superimposes each image data output from each of the operation screen generation unit 17, various mark generation unit 18, and guide route drawing unit 24 on the map image data read by the read control unit 15. To compose the image. Reference numeral 26 denotes a display device that displays map information around the host vehicle along with vehicle position marks, landmarks, and the like based on image data output from the image composition unit 25. When the guide route is set, the guide route is displayed on the map.

  FIG. 2 is a diagram illustrating an example of positioning of GPS satellites in the GPS receiver 6 of the navigation device 1 according to the present embodiment. In FIG. 2, reference numeral 50a denotes a GPS satellite selected according to a predetermined condition, and exists in the direction of Aθ when a predetermined direction (for example, north) is set to 0 °. Reference numerals 50b and 50c denote other GPS satellites that are used to detect the absolute position of the host vehicle. The GPS satellite azimuth detecting unit 6 detects the absolute position of the host vehicle by receiving radio waves from the three GPS satellites 50a, 50b, 50c, and based on the absolute position and the absolute position of the selected GPS satellite 50a. The direction Aθ of the GPS satellite 50a is acquired.

  FIG. 3 is a diagram illustrating an example of positioning of the GPS satellite 50a in the antenna direction detection unit 8 of the navigation device 1 according to the present embodiment. In FIG. 3, reference numeral 40 denotes the host vehicle, and the directivity pattern of the GPS antenna 5 mounted on the host vehicle 40 is predetermined with respect to a direction (for example, forward direction) specified in the host vehicle 40 by the antenna control unit 7. It is rotated over 360 ° by an angle (for example, by 1 °). The antenna direction detection unit 8 measures the intensity of the received radio wave from the GPS satellite 50a and detects the angle at which the intensity of the received radio wave from the GPS satellite 50a is the strongest. Obtained as the direction AntΔθ.

FIG. 4 is a diagram illustrating a concept of calculating the direction of the host vehicle 40 in the vehicle direction calculation unit 9 of the navigation device 1 according to the present embodiment. In FIG. 4, the azimuth S in the forward direction of the host vehicle 40 (a predetermined direction specified in the host vehicle 40) is determined by using the azimuth Aθ of the GPS satellite 50 a and the direction AntΔθ of the GPS satellite 50 a viewed from the host vehicle 40. Is specified by the following formula (1).
S = Aθ−AntΔθ (1)

  Next, the operation of the navigation device and the direction detection method according to the present embodiment will be described. FIG. 5 is a flowchart illustrating the operation of the navigation device and the direction detection method according to the present embodiment. In FIG. 5, first, the antenna control unit 7 rotates the directivity pattern of the GPS antenna 5 over 360 ° by 1 ° with respect to the direction (for example, forward direction) specified in the host vehicle 40 (step S1). . During this time, the GPS antenna 5 receives radio waves from the plurality of GPS satellites 50a to 50c and outputs them as GPS signals to the GPS satellite azimuth detecting unit 6 (step S2).

  The antenna direction detector 8 measures the intensity of the radio wave received by the GPS antenna 5 (step S3). Then, the antenna direction detecting unit 8 checks whether the rotation angle information of the directivity pattern is obtained from the antenna control unit 7 last time and is greater than the intensity of the received radio wave when temporarily stored in the buffer (step S4).

  If the received radio wave intensity measured by antenna direction detector 8 is greater than the previous intensity (YES in step S4), antenna direction detector 8 updates and stores rotation angle information of the directivity pattern in a buffer. In addition, a control signal is output to the GPS satellite azimuth detecting unit 6. The GPS satellite azimuth detection unit 6 inputs a control signal, and updates and stores the GPS satellite azimuth information at that time in the buffer (step S5). On the other hand, if the intensity of the received radio wave measured by antenna direction detector 8 is smaller than the previous intensity (NO in step S4), the process jumps to step S6.

  Then, the antenna direction detection unit 8 checks whether the directivity pattern of the GPS antenna 5 has changed by 360 ° (step S6). If the directivity pattern has not changed by 360 ° (NO in step S6), the process returns to step S1. On the other hand, when the directivity pattern changes by 360 ° (YES in step S6), the azimuth Aθ of the GPS satellite 50a is read from the buffer of the GPS satellite azimuth detecting unit 6 and the received radio wave is received from the buffer of the antenna direction detecting unit 8. The rotation angle of the directivity pattern when the intensity is strongest is read out as the direction AntΔθ of the arbitrary GPS satellite 50a viewed from the host vehicle 40 (step S7).

  Then, the vehicle direction calculation unit 9 determines the direction S of the host vehicle 40 based on the direction AntΔθ of the arbitrary GPS satellite 50a viewed from the host vehicle 40 obtained in step S7 and the direction Aθ of the GPS satellite 50a. (1) is calculated (step S8).

  As described above in detail, in the present embodiment, the GPS satellite 50 a is captured by changing the directivity pattern of the GPS antenna 5, and the direction AntΔθ of the GPS satellite 50 a viewed from the host vehicle 40 is detected. Further, the azimuth Aθ of the GPS satellite 50a is detected from the GPS signal obtained at that time. The direction of the host vehicle 40 is detected based on the direction AntΔθ of the GPS satellite 50a viewed from the host vehicle 40 and the direction Aθ of the GPS satellite 50a. As a result, the direction of the host vehicle 40 can be detected without causing the host vehicle 40 to travel, so the host vehicle 40 is traveling in the back direction or is present in a location where magnetic field disturbance occurs. Even in this case, the azimuth of the host vehicle 40 can be accurately detected, and the user can always grasp the correct azimuth of the host vehicle 40.

  In the above embodiment, the directivity pattern is changed by using an antenna capable of electrically directing directivity in a desired direction as the GPS antenna 5, but the present invention is not limited to this. For example, as shown in FIG. 6, a GPS antenna 55 having directivity only in a predetermined direction is used, and a rotating unit 60 for mechanically mounting the GPS antenna 55 is provided. While measuring the intensity of the received radio wave from 55, the rotation angle may be acquired from the rotating unit 60.

  Moreover, in the said embodiment, although the direction of the own vehicle 40 is detected only based on the GPS signal received with the GPS antenna 5, it is not limited to this. For example, the position information of the host vehicle 40 is input from a direction detection means such as a self-contained navigation sensor or a geomagnetic sensor, or a GPS receiver, and the direction of the host vehicle 40 is detected according to a change in the position of the host vehicle 40 due to the movement of the vehicle. You may use an orientation detection means together. Further, when these azimuth detecting means cannot accurately detect the azimuth, the vehicle azimuth calculating unit 9 may detect the azimuth of the host vehicle 40.

  In the above embodiment, the GPS satellite 50a having the highest received radio wave intensity is selected from the three GPS satellites 50a to 50c. However, the present invention is not limited to this. For example, as shown in FIG. 7, when the rotation angle of the directivity pattern is changed from among the three GPS satellites 50a to 50c, the GPS satellite 50a that appears first is selected, and the absolute position of the host vehicle 40 The GPS satellite capture may be terminated at a point in time when detection of the third GPS hygiene 50c is completed. Thereby, the acquisition time of the GPS satellite 50a can be shortened. Further, the GPS satellite 50c that appears last when the rotation angle of the directivity pattern is changed may be selected from the three GPS satellites 50a to 50c. As a result, the time lag from when the GPS satellite 50c is captured until the direction of the host vehicle 40 is detected can be reduced.

  Moreover, in the said embodiment, although the absolute position of the own vehicle 40 is detected using the three GPS satellites 50a-50c, you may use more GPS satellites than this.

  In the above embodiment, the direction in which the directivity pattern of the GPS antenna 5 first faces (reference direction) matches the direction specified in the host vehicle 40 (for example, the front direction). Depending on the case, it may be considered that they do not match. For this reason, when the GPS antenna 5 is attached to the host vehicle 40, the traveling locus of the host vehicle 40 is acquired by causing the host vehicle 40 to travel forward for a while. Then, a deviation between the direction of the travel locus and the direction of the directivity pattern of the GPS antenna 5 may be acquired and adjusted when the direction of the host vehicle 40 is detected.

  In addition, each of the above-described embodiments is merely an example of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed in a limited manner. In other words, the present invention can be implemented in various forms without departing from the spirit or main features thereof.

  The present invention is useful for a navigation device having a function of detecting the direction of the host vehicle.

It is a block diagram which shows the structural example of the navigation apparatus by this embodiment. It is a figure which shows the example of the positioning of the GPS satellite in a GPS receiver. It is a figure which shows the example of the positioning of the GPS satellite in an antenna direction detection part. It is a figure which shows the concept of the calculation of the direction of the own vehicle. It is a flowchart which shows operation | movement of the navigation apparatus by this embodiment, and a direction detection method. It is a figure which shows the modification of the change of the directivity pattern of a GPS antenna. It is a figure which shows the example of the intensity | strength of the received radio wave from a some GPS satellite.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Navigation apparatus 5 GPS antenna 6 GPS receiver 7 GPS satellite direction detection part 8 Antenna direction detection part 9 Vehicle direction calculation part 10 GPS receiver

Claims (8)

A GPS antenna for receiving radio waves from GPS satellites;
An antenna control unit that sequentially changes the directivity pattern of the GPS antenna with reference to a predetermined direction in the host vehicle;
An antenna direction detector that detects an angle of the directivity pattern when the GPS antenna receives a radio wave from the GPS satellite;
A GPS satellite azimuth detector that detects the azimuth of the GPS satellite by radio waves received by the GPS antenna;
A vehicle direction calculation unit that detects the direction of the host vehicle using the angle of the directivity pattern detected by the antenna direction detection unit and the direction of the GPS satellite detected by the GPS satellite direction detection unit;
A navigation device characterized by comprising: The antenna direction detection unit measures the intensity of the radio wave received by the GPS antenna at each angle that sequentially changes the directivity pattern of the GPS antenna, and determines the directivity pattern when the radio wave intensity is strongest. Configured to detect angles,
2. The GPS satellite azimuth detecting unit is configured to detect the azimuth of the GPS satellite based on a radio wave received by the GPS antenna when the intensity of the radio wave is strongest. Navigation device. The antenna direction detection unit measures the strength of radio waves received by the GPS antenna at each angle that sequentially changes the directivity pattern of the GPS antenna, and relates to the strength of the radio waves when the GPS antenna rotates once. Configured to detect an angle of the directivity pattern when a peak is last detected;
The GPS satellite azimuth detecting unit is configured to detect the azimuth of the GPS satellite based on a radio wave received by the GPS antenna when a peak related to the strength of the radio wave is last detected. The navigation device according to claim 1. The angle of the directivity pattern detected by the antenna direction detector is AntΔθ,
When the direction of the GPS satellite detected by the GPS satellite direction detector is Aθ,
The direction S of the host vehicle is S = Aθ−AntΔθ
The navigation device according to any one of claims 1 to 3, wherein the navigation device is configured as follows. A first step of sequentially changing the directivity pattern of the GPS antenna;
A second step in which the GPS antenna receives radio waves from a GPS satellite;
The GPS antenna detects the angle of the directivity pattern of the GPS antenna when the GPS antenna receives a radio wave from the GPS satellite in the second step, and the radio wave received by the GPS antenna in the second step. A third step of detecting the orientation of the GPS satellite by:
A fourth step of calculating the direction of the host vehicle based on the angle of the directivity pattern detected by the third step and the direction of the GPS satellite;
An orientation detection method comprising: A first step of sequentially changing the directivity pattern of the GPS antenna;
A second step in which the GPS antenna receives radio waves from a GPS satellite;
The strength of the received radio wave at each angle of the directional pattern of the GPS antenna is examined, the angle of the directivity pattern when the intensity of the received radio wave is the strongest, and the intensity of the received radio wave is the strongest. A third step of detecting the direction of the GPS satellite from the radio wave received by the GPS antenna;
A fourth step of calculating the direction of the host vehicle based on the angle of the directivity pattern detected by the third step and the direction of the GPS satellite;
An orientation detection method comprising: A first step of sequentially changing the directivity pattern of the GPS antenna;
A second step in which the GPS antenna receives radio waves from a GPS satellite;
The intensity of the received radio wave at each angle of the directional pattern of the GPS antenna is examined, and the angle of the directional pattern when the peak related to the intensity of the radio wave is detected last when the GPS antenna makes one revolution is detected. And a third step of detecting the direction of the GPS satellite by the radio wave received by the GPS antenna when the peak related to the intensity of the radio wave was last detected;
A fourth step of calculating the direction of the host vehicle based on the angle of the directivity pattern detected by the third step and the direction of the GPS satellite;
An orientation detection method comprising: When the angle of the directivity pattern acquired by the third step is AntΔθ and the azimuth of the GPS satellite is Aθ,
In the fourth step, the direction S of the own vehicle is changed to S = Aθ−AntΔθ
The azimuth detection method according to any one of claims 5 to 7, wherein:

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