JP4268581B2 - Car navigation system - Google Patents

Description

  The present invention relates to an in-vehicle navigation device, and more particularly to an in-vehicle navigation device for performing measurement of a current position by a self-supporting navigation system with higher accuracy.

  The current in-vehicle navigation system uses two types of methods, satellite navigation that mainly uses GPS (Global Positioning System) and autonomous navigation that detects the current position by calculation, in order to detect the current position. The current position is detected by using it.

  Of the above two methods, satellite navigation using GPS receives radio waves transmitted from three or more GPS satellites by a GPS receiver, and determines the position of each satellite and the transmission time of radio waves from each hygiene. By counting, the distance from each satellite is calculated to detect the absolute position of the vehicle. On the other hand, current position detection by self-contained navigation is to detect the current position in tunnels or buildings where it is difficult to receive GPS satellite radio waves. Distance sensors that calculate the distance from the rotation of the wheels and movement directions are calculated. The current position is estimated by a gyro for the purpose.

A specific example of the above-described current position detection method will be described below with reference to FIG. FIG. 6 is a block diagram of the absolute position calculation means of the in-vehicle navigation device described in Patent Document 1 below.
The in-vehicle navigation device described in the following Patent Document 1 (Japanese Patent Application Laid-Open No. 09-280877) includes traveling direction calculation means 101 that calculates a relative direction of a moving body such as an automobile from a gyro, and traveling of the moving body from the rotation of a wheel. Travel distance calculating means 102 for calculating the distance, absolute azimuth calculating means 104 for calculating the absolute azimuth using the relative azimuth calculated by the traveling azimuth calculating means 101 and the GPS azimuth output from the GPS receiver, and absolute azimuth calculation A vector calculation unit 105 that calculates a travel vector using the absolute azimuth calculated by the unit 104 and the travel distance calculated by the travel distance calculation unit 102, and an absolute position is obtained by integrating the travel vector calculated by the vector calculation unit 105. When the GPS position is calculated and obtained from the GPS receiver, the absolute position is initialized using the GPS position. Constituted by the position calculating means 106.

  Further, the vector calculation unit 105 calculates a travel vector having a travel distance as a length and an absolute direction as a fixed travel time from the travel distance calculated by the travel distance calculation unit 102 and the absolute direction calculated by the absolute direction calculation unit 104. Alternatively, the absolute position calculation means 106 calculates the latitude and longitude of the initial position determined by the system as the orthogonal coordinate component using the travel vector calculated by the vector calculation means 105 every fixed time or every fixed distance. The current position is detected by sequentially adding the decomposed difference latitude and difference longitude to calculate and update the absolute position.

  With the above-described configuration, it becomes possible to perform position detection continuously and with high accuracy regardless of reception or non-reception of the GPS receiver using only the self-contained navigation sensor.

JP 09-280877 A (FIG. 1, paragraphs [0016], [0027] to [0028])

  However, in the position detection method by the self-contained navigation system as in the above-mentioned Patent Document 1, there is a drawback that the deviation from the actual trajectory increases as the calculation is repeated with the current position as the point that has been advanced by the travel distance in the direction of the detected vector. There is. FIG. 7 is a diagram showing the transition of the absolute position when the vehicle traveling on the right curve travels with a relative angle change of 10 ° per second.

  In other words, conventionally, the current position is detected by self-contained navigation with the direction of the vehicle detected by an angle sensor (gyro) as the vector direction and the travel distance detected by the distance sensor as the vector length. As shown in FIG. 7, for example, when the actual road R has a substantially concentric curve, the direction of the vehicle detected by the gyro is detected after the movement is started, and therefore slightly inside the road R. Transition. When this direction is detected as the direction of the traveling direction vector ER of the estimated route, the detected current position is cut inward from the actual position. As a result, the traveling direction and the travel distance are shifted. Further, since the progress vector ER is detected by being sequentially added to the previous progress vector every time the positioning is performed, the error increases as the current position positioning progresses. Position detection becomes more difficult. This is particularly a problem when traveling on a loop bridge, for example, and there are often other roads on the loop bridge, so it is difficult to detect the current position by satellite navigation for a long time. It will run. In such a case, the current position cannot be accurately detected by the self-contained navigation due to the above-mentioned problems, and thus there is a possibility that the user may erroneously recognize.

  In view of the above-mentioned problems, the present inventors obtained various results of highly accurate detection methods of the current position at a point where satellite navigation such as a loop bridge cannot be performed in an in-vehicle navigation device. If the current position is found on the assumed route that approximates the arc or arc from the relative direction and travel distance, when traveling on a road that uses a clothoid curve such as an arc road or expressway Has also found that the current position can be detected with high accuracy, and has reached the present invention.

  That is, an object of the present invention is to provide an in-vehicle navigation device capable of detecting a current position with higher accuracy in a self-contained navigation system in an in-vehicle navigation device.

In order to achieve the above object, the in-vehicle navigation device according to claim 1 includes a relative azimuth change amount detecting means for detecting a change amount of the relative azimuth of the own vehicle by an angle sensor, and a travel distance of the own vehicle by a distance sensor. Travel distance detection means for detecting the vehicle position, current position calculation means for detecting the vehicle position from the output results of the relative azimuth change detection means and the travel distance detection means output at predetermined time intervals, and the current position A vehicle-mounted navigation device comprising a self-contained navigation system comprising: a drawing data storage unit for storing position coordinates detected by a computing means;
The current position calculation means sets the relative azimuth change detected by the relative azimuth change detection means to θ, sets the travel distance detected by the travel distance detection means to L, and proceeds at the position coordinates detected immediately before. In the xy coordinate system with the direction as the y-axis, the relative azimuth variation θ and the travel distance L are divided into N, and the travel distance L / N is calculated in the travel direction θ / N from the position coordinates detected immediately before. The present invention is characterized in that the current position of the host vehicle is detected by performing position detection for detecting the advanced position a total of N times.

Further, an invention according to claim 2 relates to a vehicle navigation apparatus according to claim 1, wherein the drawing data storage unit, said detected by the detection process of the position coordinates detected at the current position calculating means position Coordinates are also stored, and a trajectory obtained by connecting position coordinates detected in the process of detecting the position coordinates of the current position is displayed on the display unit as a travel trajectory of the host vehicle.

The in-vehicle navigation device according to claim 3 is a relative azimuth change amount detecting means for detecting a change amount of the relative azimuth of the own vehicle by an angle sensor, and a travel distance detecting means for detecting a mileage of the own vehicle by a distance sensor. A current position calculation means for detecting the position of the vehicle from the output results of the relative azimuth change detection means and the travel distance detection means output at predetermined time intervals, and position coordinates detected by the current position calculation means A vehicle-mounted navigation device equipped with a self-contained navigation system comprising a drawing data storage unit for storing
The current position calculation means sets the relative azimuth change detected by the relative azimuth change detection means to θ, sets the travel distance detected by the travel distance detection means to L, and proceeds at the position coordinates detected immediately before. In the xy coordinate system having the direction as the y-axis, the relative azimuth change amount θ and the travel distance L are divided into N, and the travel distance in the traveling direction (θ / 2) / N from the position coordinates detected immediately before. A current position of the host vehicle is detected by detecting a position advanced by L / N and performing position detection for detecting a position further advanced by a travel distance L / N in the traveling direction θ / N from this position a total of N−1 times. Is detected.

Further, the invention according to claim 4 relates to a vehicle navigation apparatus according to claim 3, wherein the drawing data storage unit, said detected by the detection process of the position coordinates detected at the current position calculating means position Coordinates are also stored, and a trajectory obtained by connecting position coordinates detected in the process of detecting the position coordinates of the current position is displayed on the display unit as a travel trajectory of the host vehicle.

By providing the above configuration, the present invention can obtain the following effects. That is, according to the first aspect of the present invention, the relative azimuth change amount θ detected by the relative azimuth change amount detection unit and the travel distance L detected by the travel distance detection unit are used to calculate the relative azimuth. By dividing the change amount θ and the travel distance L into N, and performing position detection for detecting a position advanced by the travel distance L / N in the traveling direction θ / N from the position coordinates detected immediately before, a total of N times, Since the current position of the host vehicle is detected, a method of detecting the current position from a traveling vector having a length of the travel distance L in the direction of the relative azimuth change θ from the previously determined position coordinates as in the prior art. Compared to, the current position is detected by drawing a travel locus that is closer to a circular orbit from the previously determined position coordinates. Present position It is possible to perform the detection.

According to the second aspect of the present invention, the drawing data storage unit stores the coordinate data between the position coordinate detections performed at predetermined intervals derived by performing the current position detection method according to the first aspect. Then, this data is displayed on the display unit by performing map matching or the like in the same manner as normal position coordinate data (position coordinate detection result performed at a predetermined interval), so that the update speed is not restricted by the time interval of position coordinate detection. Display can be performed, and further, continuous display such as scroll display can be performed.

According to a third aspect of the present invention, the relative azimuth change amount is detected by using the relative azimuth change amount θ detected by the relative azimuth change amount detection means and the travel distance L detected by the travel distance detection means. θ and the travel distance L are divided into N, and a position advanced by the travel distance L / N in the traveling direction (θ / 2) / N is detected from the position coordinates detected immediately before, and the traveling direction θ is further detected from this position. The current position of the vehicle is detected by performing position detection for detecting the position advanced by the travel distance L / N at / N a total of N−1 times, and thereby the travel locus of the vehicle traveling on the circular orbit is represented by the circle. Assuming a polygon that is inscribed in and drawing a progression vector similar to each side of the polygon, the current position can be detected with higher accuracy.

According to a fourth aspect of the present invention, the drawing data storage unit stores coordinate data between position coordinate detections performed at predetermined intervals derived by performing the current position detection method according to the third aspect. Then, this data is displayed on the display unit by performing map matching or the like in the same manner as normal position coordinate data (position coordinate detection result performed at a predetermined interval), so that the update speed is not restricted by the time interval of position coordinate detection. Display can be performed, and further, continuous display such as scroll display can be performed.

  Hereinafter, the best embodiment of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies an in-vehicle navigation device for embodying the technical idea of the present invention, and is not intended to specify the present invention. Other embodiments within the scope are equally applicable.

An in-vehicle navigation device according to an embodiment of the present invention will be described below.
FIG. 1 is a functional block diagram of an in-vehicle navigation device according to Embodiment 1 of the present invention, and FIG. 2 is a diagram schematically showing a method for detecting the position coordinates of a moving vehicle.

  The in-vehicle navigation device 1 of the present invention is mounted on a vehicle, and includes a GPS receiving unit 10, a GPS data storage unit 11, a self-contained navigation sensor 12, a current position calculation unit 13, a CDROM 14, a map buffer 15, a position The correction unit 16, the drawing control unit 17, the operation unit 18, and the display unit 19 are included. The navigation device 1 operates satellite navigation and independent navigation in parallel.

  The GPS receiver 10 is used when the vehicle performs satellite navigation, receives radio waves from a plurality of GPS satellites 10a, and calculates and outputs the position of the vehicle from the distance to the plurality of GPS satellites 10a. The GPS data storage unit 11 stores the positioning data received by the GPS receiving unit 10.

  The self-contained navigation sensor 12 is used when performing self-contained navigation. The self-contained navigation sensor 12 is mounted on a vehicle wheel and detects a travel distance from a pulse signal output by rotation of the wheel, a mechanical gyroscope, and a vibration gyroscope. And an angle sensor 12b that detects a moving direction and a relative direction change amount of the vehicle by an acceleration sensor or the like. The current position calculation unit 13 outputs results of the distance sensor 12a and the angle sensor 12b. The current position of the vehicle is detected from the above, and the method for detecting the current position will be described later. The CDROM 14 stores map data around the running position of the vehicle, and the map buffer 15 temporarily stores the map data stored in the CDROM 14.

  The position correction unit 16 includes a map matching control unit 16a and a drawing data storage unit 16b. The drawing data storage unit 16b is based on the data received by the GPS receiving unit 10 and is detected by satellite navigation and detected by various sensors. Is used to store the current position data and the traveling locus, etc., based on the current position calculation result detected by the self-contained navigation, and the map matching control unit 16a uses the map data in the CDROM 14 and the current detected by the satellite navigation or the self-contained navigation. The position and the running trajectory are matched. For this map matching, the vehicle position obtained by the satellite navigation or the independent navigation is projected on the nearest road in the road data, and the vehicle position mark is corrected on the correct road. And the trajectory of the vehicle position obtained by the satellite navigation or the independent navigation. There are two pattern matching methods that compare the road shape in the road data to find the correct road while driving and correct it on the road. In this embodiment, map matching is performed using either of them. As a method, a known method is used, and detailed description is not given here.

  The drawing control unit 17 includes a vehicle position drawing unit 17a and a map drawing unit 17b. The vehicle position drawing unit 17a includes the current position data and the traveling locus on which the map matching is performed by the map matching control unit 16a of the position correction unit 16. Map data is drawn together, and the map drawing unit 17b is a part that draws a map when only displaying a map. The operation unit 18 performs various operations such as setting a destination or changing a display map when performing a route search. The display unit 19 displays map data or a route display drawn by the drawing control unit 17. The performed drawing data is displayed on a liquid crystal display panel (not shown) or the like.

Next, a current position detection method executed in the current position calculation unit 13 will be described.
When self-contained navigation is executed and current position detection is started by the current position calculation unit 13, the current position calculation unit 13 first refers to a preset time interval (for example, one second interval), The current position is detected every time the time interval elapses. FIG. 2 is a diagram illustrating a state in which a vehicle equipped with the vehicle-mounted navigation device according to the first embodiment of the present invention travels on a left-turn curve. Here, the vehicle 20 will be described the current position detection method when moving from the vehicle position P1 is previously determined _(x 1, _{y 1)} to the vehicle position after a predetermined time _{P2 (x 2, y 2)} . In the xy coordinate system in which the vehicle position coordinates are drawn in FIG. 2, the direction of the vehicle 20 at the vehicle position whose y axis has been previously determined is displayed as the y coordinate.

  When the self-contained navigation is started and the vehicle 20 approaches a left curve as shown in FIG. 2, the angle sensor 12b detects a relative azimuth change amount having a predetermined magnitude. At this time, the current position calculation unit 13 assumes that the vehicle is traveling on an arc or a route approximate to the arc, and calculates a travel locus on the assumption that the vehicle is traveling on the circumference of a circle having a radius r.

That is, in the current position calculation unit 13, from the positioning position P1 (x ₁ , y ₁ ) detected by the previous satellite navigation or the autonomous navigation to the position P2 (x ₂ , y ₂ ) detected by the autonomous navigation after a predetermined time has elapsed. When moving, assuming that the amount of movement traveled on an arc of radius r, the relative azimuth change amount is θ (θ ≠ 0, −π / 2 ≦ θ ≦ π / 2) (where θ is on the y axis) 0, counterclockwise direction is + direction), and when the position P2 is viewed from the center of the radius r,
r · cosθ in the x-axis direction
r · sinθ in the y-axis direction
In the position. That is, the amount of movement of this position P2 from the previous positioning position P1 is
In the x-axis direction, r · cos θ-r (X0)
In the y-axis direction r · sin θ (Y0)
It is.

In the above equation, r is an unknown number, but from the relationship between the entire circumference of the arc, the relative azimuth change amount θ, and the travel distance L,
2 · r · π · (θ / (2 · π)) = L (π = circumference ratio)
r = L / θ
Therefore, if this is substituted into the equations (X1) and (Y1), the displacement from the previous vehicle position P1 is
In the x-axis direction (L / θ) · (cos θ-1) (X1)
In the y-axis direction (L / θ) · sinθ (Y1)
It can be expressed as.

The current position calculation unit 13 calculates the above formulas (X1) and (Y1) using the relative azimuth change amount θ and the travel distance L detected at a predetermined time interval (for example, 1 second interval), thereby calculating the predetermined time. The movement amount at the current position can be calculated, and the position coordinate (P2 (x ₂ , y ₂ ) of the current position is obtained by sequentially adding this movement amount to the position coordinate (P 1 (x ₁ , y ₁ )) previously determined ) Can be detected. According to this method, there is no error in travel distance or travel angle caused by calculating a linear vector for a vehicle that moves on an arc as in the prior art, so that more accurate current position detection is possible. Thus, the current position obtained by the current position calculator 13 can be detected with high accuracy even when the map matching controller 16a performs map matching.

  However, in the above formulas (X1) and (Y1), the relative azimuth change amount θ = 0, that is, the vehicle 20 is traveling in a linear direction, and thus cannot be applied. Therefore, the vehicle is traveling in a linear direction. In this case, the distance traveled by L in the traveling direction in the previously determined position coordinates is calculated as the vehicle position.

  In addition, here, the case where the relative azimuth change amount θ is −π / 2 ≦ θ ≦ π / 2 has been described, but if it is desired to apply to a region exceeding ± π / 2, an equation is similarly calculated from the geometric condition. That's fine. However, if the detection interval of the self-contained navigation sensor 12 is set to 1 second, for example, it is difficult to consider a case where a relative azimuth change amount exceeding ± π / 2 is detected in 1 second. Therefore, here θ is −π / 2 ≦ θ. Only the case of ≦ π / 2 will be described.

Next, the current position detection process when the route guidance is performed by the vehicle-mounted navigation device according to the present embodiment will be described below with reference to FIG. FIG. 3 is a flowchart showing the current position detection process.
First, when the vehicle-mounted navigation device 1 is activated and route guidance is performed, the detection time interval T1 of the self-contained navigation sensor 12 preset in step S1 and the radio wave reception time from the satellite in the GPS receiver 10 are set. The interval T2 is acquired. The T1 is set with a timing at which the self-contained navigation sensor 12 detects the travel distance and the relative azimuth change amount when performing the self-contained navigation, and is set at a relatively short interval (for example, one second interval). The T2 is a timing for setting a communication timing with the GPS satellite. Since the communication with the GPS satellite requires a relatively long time, a time longer than the T1 is set. In step S2, positioning using the GPS satellite 10a is started. The current position positioning by satellite navigation is performed preferentially here because the current position can be measured with higher accuracy than the self-contained navigation.

  When the current position measurement by satellite navigation is started and radio waves are received by the GPS receiver 10 in step S3, received data from a plurality of GPS satellites 10a received by the GPS receiver 10 are received in step S4. The distance from each GPS satellite is calculated from the communication speed with the GPS satellite, the calculated distance from the GPS satellite is stored in the GPS data storage unit 11, and the current position is calculated from the data. In step S5, the calculated current position is corrected on the map, for example, on the road around the current position stored in the map buffer 15 by the map matching control unit 16a. Subsequently, in step S6, the map buffer 15 The current position where the map matching is performed on the surrounding map and the travel locus of the host vehicle are drawn together in the vehicle position drawing unit 17 a and displayed on the display unit 19.

  Here, if route guidance is set, it is detected whether or not the destination has been reached, and if it has not reached the destination, it is detected whether or not T2 has elapsed. If the destination is reached, the route guidance is terminated. If the destination is not reached and T2 has elapsed, the process returns to step S2, and the current position detection by GPS reception is performed again (steps S7, S8).

  If it is determined in step S3 that GPS reception cannot be performed, that is, if the vehicle is traveling in a tunnel or a high-rise building street and cannot communicate with a GPS satellite, the self-contained navigation is performed in step S9. Is started, and the current position calculation unit 13 acquires the data of the travel locus so far or the data of the position coordinates determined last time from the drawing data storage unit 16b. Further, in step S10, the travel distance and the relative azimuth change amount from the self-contained navigation sensor 12 are acquired, and the previously determined position coordinates and sensor output acquired in steps S9 and S10 are used to calculate the equations (X1) and (Y1). The current position is calculated and output (step S11). In step S12, the calculated current position is corrected on the map, for example, on the road around the current position stored in the map buffer 15 by the map matching control unit 16a. Subsequently, in step S13, the map position in the map buffer 15 is corrected. The vehicle position drawing unit 17a draws the current position where the map matching has been performed on the surrounding map of the vehicle and the traveling locus of the host vehicle, and displays them on the display unit 19.

  Here, if route guidance is set, it is detected whether or not the destination has been reached, and if it has not reached the destination, it is detected whether or not T1 has elapsed. If the destination has been reached, the route guidance is terminated. If the destination has not been reached and T1 has elapsed, the process returns to step S9, and the current position calculation unit 13 performs current position detection again (steps S14 and S15). . Incidentally, at this time, GPS reception is continuously performed, and when the GPS reception is restored, the process immediately proceeds to step S4 to display the current position based on the GPS reception result.

  According to the above-described method, by performing both satellite navigation and self-contained navigation, it is possible to calculate the current position with higher accuracy even at locations where GPS reception is not possible, as well as locations where GPS reception is possible. As a result, the current position display and route guidance can be performed with higher accuracy.

  Further, an in-vehicle navigation device based on self-contained navigation using a current position detection unit different from that of the first embodiment is shown below. However, the configuration of the in-vehicle navigation device according to the present embodiment is the same as that of the first embodiment, and only the calculation method of the current position calculation unit 13 is different from the first embodiment. The description which overlaps is abbreviate | omitted and only a different part shall be demonstrated. Further, since the current position detection process shown in FIG. 3 is the same, the description of the current position detection procedure is omitted.

FIG. 4 is a diagram showing an example in which the current position is detected in the second embodiment in an easy-to-understand manner. The y coordinate in FIG. 4 is a traveling direction at the position coordinates P3 (x ₃ , y ₃ ), and this y axis The clockwise direction is the + direction, and the relative azimuth change amount θ from the position coordinate P3 (x ₃ , y ₃ ) to the position coordinate P4 (x ₄ , y ₄ ) in the figure is 20 °.
The current position detection unit 13 mounted on the in-vehicle navigation device of the present embodiment travels at a predetermined time interval when traveling from the previously determined position coordinate P3 to the position coordinate P4 where the sensor output of the self-contained navigation sensor is performed after a predetermined time. Each of the travel distance L and the relative azimuth change amount θ detected from the distance sensor 12a and the angle sensor 12b is divided into a plurality (N), and the relative azimuth change amount θ / N direction divided from the previously determined position coordinate P3. A travel vector having a length of travel distance L / N is calculated, and a point where N travel vectors are connected is detected as a current position.

  Describing in detail with reference to FIG. 4, when the current position is detected by self-contained navigation while the vehicle 20 is traveling on a road R having a gentle right curve, conventionally, from the position coordinate P <b> 3 previously determined. When the position coordinates of the vehicle after a predetermined time (T1) are detected, the vehicle is moved relative to the actual road R in the direction of the relative azimuth change θ (20 °) from the previously determined position coordinates P3 as shown by the travel vector ER1 in the figure. Since the position shifts inward, the detected position coordinate P4 ″ after a predetermined time is detected as a position considerably away from the actual position coordinate P4.

On the other hand, when the current position detection method according to the present embodiment is applied, as shown in FIG. 4, based on the relative azimuth change θ = 20 ° and the travel distance L output when the point P4 is reached. First, the relative azimuth change amount θ and the travel distance L are divided by the number of divisions N = 10, and a travel vector 30 having a length of the travel distance L / N in the divided relative azimuth change amount θ / N direction is determined last time. Subtract from the position coordinate P3 (x ₃ , y ₃ ). Further, the traveling vector having the length of the traveling distance L / N in the direction of the relative azimuth variation θ / N divided in the same manner from the coordinates 40 at the tip of the traveling vector 30 drawn from the position coordinates P3 (x ₃ , y ₃ ). 31 is obtained, and the coordinate 41 of the tip is obtained. And the position coordinate P4 'calculated | required as a result of performing this process N (10) times is detected as a position coordinate in P4 point.

  According to this method, although a slight error remains, the error can be remarkably reduced as compared with the conventional method as is apparent from FIG. Therefore, in the subsequent map matching processing, it is possible to display the current position that substantially matches the actual position.

  Further, in the current position detection method according to the present embodiment, since the position coordinates detected at predetermined time intervals are simultaneously detected in addition to the position coordinates detected at predetermined time intervals T1, Can also be map-matched and displayed on the display unit 19, so that, for example, the current position can always be updated even when the update speed of the display unit 19 is shorter than the predetermined time T1, Smooth scroll display can be performed.

  As still another current position detection method, an in-vehicle navigation device according to Example 3 will be described below. However, the configuration of the in-vehicle navigation device according to the present embodiment is the same as that of the first embodiment, and only the calculation method of the current position calculation unit 13 is different from that of the first embodiment. The overlapping description of the configuration will be omitted, and only different parts will be described. Further, since the current position detection process shown in FIG. 3 is the same, the description of the current position detection procedure is omitted.

FIG. 5 is a diagram showing an example in which the current position is detected in the third embodiment in an easy-to-understand manner. The y coordinate in FIG. 5 is the traveling direction at the position coordinate P5 (x ₅ , y ₅ ), The clockwise direction is the + direction, and the relative azimuth change amount θ from the position coordinate P5 (x ₅ , y ₅ ) to the position coordinate P6 (x ₆ , y ₆ ) in the figure is 20 °.
The current position detection unit 13 mounted on the vehicle-mounted navigation device of the present embodiment travels at a predetermined time interval when traveling from the previously determined position coordinate P5 to the position coordinate P6 where the sensor output of the self-contained navigation sensor is performed after a predetermined time. Each of the travel distance L and the relative azimuth change amount θ detected from the distance sensor 12a and the angle sensor 12b is divided into a plurality (N), and the relative azimuth change amount (θ / 2) divided from the previously determined position coordinate P5. The travel vector (50) having the length of the travel distance L / N in the / N direction is calculated, and the travel distance L / N in the relative azimuth change θ / N direction divided from the end point (60) of the travel vector is calculated. A progression vector (51) having a length is calculated, and a point where (N-1) progression vectors are connected is detected as a current position.

  As described above, the first vector divided into N pieces is subtracted at an angle of (θ / 2) / N. The relative azimuth change amount θ is divided into N parts. Equivalent to dividing 2 · π / θ. Accordingly, an N · 2 · π / θ square inscribed in the circular orbit is assumed. At this time, the relative azimuth change amounts θ when tracing each side of the polygon in turn are θ / N, respectively, but since the first line segment is the relative azimuth change amount from the previous travel vector, θ / This is because a change amount of 1/2 of N is sufficient. For the second and subsequent lines, the change amount of θ / N may be sufficient.

  Describing in detail with reference to FIG. 5, when the current position is detected by self-contained navigation while the vehicle 20 is traveling on a road R that forms a gentle right curve, conventionally, from the position coordinate P5 previously determined. When the position coordinates of the vehicle after a predetermined time (T1) are detected, the actual road R is moved in the direction of the relative azimuth change θ (20 °) from the previously determined position coordinates P5 as shown in the traveling vector ER1 in the figure. Since the position is shifted inward, the detected position coordinate P6 ″ after a predetermined time is detected as a position considerably away from the actual position coordinate P6.

On the other hand, when the current position detection method according to the present embodiment is applied, as shown in FIG. 5, based on the relative azimuth change θ = 20 ° and the travel distance L output when the point P6 is reached. First, the relative azimuth change amount θ and the travel distance L are divided by the number of divisions N = 2, and the divided relative azimuth change amount θ / N is further halved (θ / 2) / the travel distance L in the N direction. A progression vector 50 having a length of / N is drawn from the previously determined position coordinate P5 (x ₅ , y ₅ ). Furthermore, from the point 60 at the tip of the traveling vector 50 drawn from the position coordinates P5 (x ₅ , y ₅ ), a traveling vector 51 having a length of the traveling distance L / N in the divided relative azimuth variation θ / N direction. . Then, the end point of the progress vector 51 is detected as the position coordinate at the point P6 as the position coordinate P6 ′.

  In the example shown in FIG. 5, the number of divisions N = 2, but even with only two divisions, the estimated current position P6 ′ can be derived at substantially the same position as the actual position coordinates P6 as apparent from FIG. Actually, since the vehicle traveling on the arc is approximated by a traveling vector consisting of a straight line, the error does not become zero, but the accuracy of the current position detection can be greatly improved. Considering that the map matching process is performed, it is possible to perform the calculation detection of the current position including almost no error. In addition, although it is divided into two here, it is of course possible to divide more than this. In that case, the direction of the second and subsequent progress vectors may be set in the direction of θ / N from the direction of the previous progress vector. If the number of divisions is increased, more accurate current position calculation output can be performed.

  Further, in the current position detection method according to the present embodiment, in addition to the position coordinates detected at predetermined time intervals T1 as in the second embodiment, the positions between the position coordinates detected at predetermined time intervals are also simultaneously detected. Since it is detected, it can be map-matched in the same manner and displayed on the display unit 19, so that, for example, even if the update speed of the display unit 19 is shorter than the predetermined time T 1, the current position is always present. Can be updated, so that a smooth scrolling display can be performed.

  Although the effectiveness of the present invention when the vehicle travels on a circular track is clear as described above, the actual trajectory of the vehicle is often a clothoid curve according to a change in steering. Highway interchanges are actually designed with clothoid curves. When traveling on such a road, if the relative azimuth change amount θ increases when the movement distance is constant, the assumed radius of the circular orbit is reduced. This is consistent with the clothoid curve, which gradually becomes tighter. Not limited to the present invention, self-contained navigation usually repeats measurement and calculation at intervals of about 1 second, so it can be considered as a circular orbit during that period, and flexibly changes to any curve as the relative direction change amount θ changes. Can also be adapted.

  Furthermore, the present position detection method of the present invention can also be used for complementation during satellite navigation. Specifically, for example, even if the current position can be detected by satellite navigation, the Dop (DOP: Dilution of Precision) value may increase due to obstacles, and the reliability of current position measurement may decrease. is there. In such a case, the position detection by the independent navigation can be performed in parallel with the position detection by the satellite navigation, so that the reliability of the position detection by the satellite navigation can be judged, and the current position can be displayed with higher accuracy. become able to.

1 is a functional block diagram of an in-vehicle navigation device according to Embodiment 1 of the present invention, FIG. 2 is a diagram illustrating a state in which a vehicle equipped with the in-vehicle navigation device of the first embodiment travels a left-turned curve; FIG. 3 is a flowchart showing the current position detection step. FIG. 4 is a diagram showing an example in which the current position is detected in Example 2 in an easy-to-understand manner. FIG. 5 is a diagram showing an example in which the current position is detected in Example 3 in an easy-to-understand manner. FIG. 6 is a configuration diagram of absolute position calculation means of a conventional in-vehicle navigation device, FIG. 7 is a diagram showing a current position detected by a conventional current position detection method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Car navigation apparatus 10 GPS receiving part 11 GPS data storage part 12 Self-contained navigation sensor 12a Distance sensor 12b Angle sensor 13 Current position calculating part 14 CDROM
15 map buffer 16 position correction unit 16a map matching control unit 16b drawing data storage unit 17 drawing control unit 17a vehicle position drawing unit 17b map drawing unit 18 operation unit 19 display unit

Claims (4)

Relative azimuth change amount detecting means for detecting the amount of change in the relative direction of the own vehicle by means of an angle sensor, mileage detecting means for detecting the mileage of the own vehicle by means of a distance sensor, and the relative azimuth change output at predetermined time intervals. A self-supporting unit comprising: a current position calculating unit that detects the position of the vehicle from the output results of the amount detecting unit and the travel distance detecting unit; and a drawing data storage unit that stores the position coordinates detected by the current position calculating unit. An in-vehicle navigation device equipped with a navigation system,
The current position calculation means sets the relative azimuth change detected by the relative azimuth change detection means to θ, sets the travel distance detected by the travel distance detection means to L, and proceeds at the position coordinates detected immediately before. In the xy coordinate system with the direction as the y-axis, the relative azimuth variation θ and the travel distance L are divided into N, and the travel distance L / N is calculated in the travel direction θ / N from the position coordinates detected immediately before. A vehicle-mounted navigation device that detects a current position of a host vehicle by performing position detection for detecting an advanced position a total of N times. The drawing data storage unit also stores the position coordinates detected in the process of detecting the position coordinates detected by the current position calculation means, and connects the position coordinates detected in the process of detecting the position coordinates of the current position The in-vehicle navigation device according to claim 2, wherein the trajectory is displayed on the display unit as a travel trajectory of the own vehicle. Relative azimuth change amount detecting means for detecting the amount of change in the relative direction of the own vehicle by means of an angle sensor, mileage detecting means for detecting the mileage of the own vehicle by means of a distance sensor, and the relative azimuth change output at predetermined time intervals. A self-supporting unit comprising: a current position calculating unit that detects the position of the vehicle from the output results of the amount detecting unit and the travel distance detecting unit; and a drawing data storage unit that stores the position coordinates detected by the current position calculating unit. An in-vehicle navigation device equipped with a navigation system,
The current position calculation means sets the relative azimuth change detected by the relative azimuth change detection means to θ, sets the travel distance detected by the travel distance detection means to L, and proceeds at the position coordinates detected immediately before. In the xy coordinate system having the direction as the y-axis, the relative azimuth change amount θ and the travel distance L are divided into N, and the travel distance in the traveling direction (θ / 2) / N from the position coordinates detected immediately before. A current position of the host vehicle is detected by detecting a position advanced by L / N and performing position detection for detecting a position further advanced by a travel distance L / N in the traveling direction θ / N from this position a total of N−1 times. In-vehicle navigation device characterized by detecting The drawing data storage unit also stores the position coordinates detected in the process of detecting the position coordinates detected by the current position calculation means, and connects the position coordinates detected in the process of detecting the position coordinates of the current position The in-vehicle navigation device according to claim 3, wherein the trajectory is displayed on the display unit as a travel trajectory of the own vehicle.

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