JP2007263683A - On-vehicle navigation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely find a current position when a plurality of closely adjacent roads exists. <P>SOLUTION: This on-vehicle navigation system is provided with a means for storing an allowance value of centrifugal force acting on a vehicle, a means for acquiring a vehicle speed, a means for finding the current position, a curve radius acquiring means for acquiring a curve radius of the road on a map with the current position existing therein, a centrifugal force calculating means for finding the centrifugal force acting on the vehicle, based on the curve radius, the vehicle speed and a prescribed weight, and a current position correcting means for finding again the current position, when the centrifugal force calculated by the centrifugal force calculating means exceeds the allowance value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle-mounted navigation device, and more particularly to a current position calculation technique for a vehicle-mounted navigation device.

Patent Document 1 describes an in-vehicle navigation device that calculates a current position of a vehicle by map matching processing based on information from a vehicle speed sensor, a direction sensor, a GPS receiver, and the like.
JP 2004-239918 A

  However, if a plurality of roads exist in the vicinity of the current position, the current position may be obtained on a road different from the road where the vehicle actually exists. For example, when a vehicle travels on a highway main road and passes a ramp road branch, it may actually find the current position on the ramp road while it continues to travel on the main highway road. is there.

  The present invention has been made to solve such a problem, and it is an object of the present invention to more reliably obtain the current position even when there are a plurality of adjacent roads.

  In order to solve the above problem, the present invention calculates the centrifugal force acting on the vehicle and corrects the current position.

  A first aspect of the present invention is an in-vehicle navigation device, wherein means for storing an allowable value of centrifugal force acting on a vehicle, means for acquiring a vehicle speed, means for obtaining a current position, and the current position exist A curve radius obtaining means for obtaining a curve radius of a road on the map, a centrifugal force calculating means for obtaining a centrifugal force acting on the vehicle from the curve radius, the vehicle speed and a predetermined weight, and a centrifugal force calculated by the centrifugal force calculating means Current position correcting means for correcting the current position when the force exceeds the allowable value.

  The current position correcting means may obtain the current position on the expressway when the centrifugal force calculated by the centrifugal force calculating means exceeds the allowable value.

  The current position correcting means may obtain the current position on a road having a speed limit faster than the road where the current position exists when the centrifugal force calculated by the centrifugal force calculating means exceeds the allowable value.

  The current position correcting means may recalculate the current position on a road that is more linear than the road where the current position exists when the centrifugal force calculated by the centrifugal force calculating means exceeds the allowable value. .

  The curve radius acquisition means obtains an intersection of vertical bisectors of a predetermined number of links ahead of the current position, and a circle including the predetermined number of links as a circumferential fragment from the obtained intersection And the radius of the circle can be made the curve radius.

  The vehicle-mounted navigation device may include means for storing map data including a curve radius for each link. And the said curve radius acquisition means may acquire the curve radius of the link in which the present position exists from the said map data.

  The on-vehicle navigation device includes means for storing information associating a vehicle type with a weight, a means for receiving an input of the vehicle type, and a means for specifying a corresponding weight from the received vehicle type. It may be.

  Further, a second aspect of the present invention is an in-vehicle navigation device, which stores means for storing an allowable value of centrifugal force acting on a vehicle, means for acquiring a vehicle speed, and means for obtaining a plurality of current position candidate points. Means for determining the reliability of the candidate point; display candidate point setting means for setting a display candidate point from a plurality of candidate points; and means for determining a curve radius of a road on the map where the display candidate point exists. And a centrifugal force calculating means for obtaining a centrifugal force acting on the vehicle from the curve radius, the vehicle speed and a predetermined weight. Then, when the centrifugal force calculated by the centrifugal force calculating unit exceeds the allowable value, the display candidate point setting unit resets a candidate point having the next highest reliability after the current display candidate point as a display candidate point. .

  An embodiment of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of an in-vehicle navigation device 100 according to the present invention. As shown in the figure, the in-vehicle navigation device 100 includes an arithmetic processing unit 1, a display 2, a storage device 3, a voice input / output device 4, an input device 5, a wheel speed sensor 6, a geomagnetic sensor 7, A gyro sensor 8 and a GPS (Global Positioning System) receiver 9 are provided.

  The arithmetic processing unit 1 is a central unit that performs various processes. For example, the present location is detected based on information output from the various sensors 6 to 8 and the GPS receiver 9. Further, map data necessary for display is read out from the storage device 3 based on the obtained current location information. Further, the read map data is developed in graphics, and a mark indicating the current location is superimposed on the map data and displayed on the display 2. In addition, the map data stored in the storage device 3 is used to search for an optimum route (recommended route) connecting the destination instructed by the user and the current location (departure location). Further, the user is guided using the voice input / output device 4 and the display 2.

  The display 2 is a unit that displays graphics information generated by the arithmetic processing unit 1. The display 2 is composed of a CRT, a liquid crystal display, or the like. The signal S1 between the arithmetic processing unit 1 and the display 2 is generally connected by an RGB signal or an NTSC (National Television System Committee) signal.

  The storage device 3 includes a storage medium such as a CD-ROM, DVD-ROM, HDD, or IC card. This storage medium stores map data.

  The map data includes, for each mesh identification code (mesh ID), which is a partitioned area on the map, link data of each link constituting a road included in the mesh area. The link data includes, for each link ID, coordinate information of two nodes (start node and end node) constituting the link, road type information including the link, link length information indicating the link length, link travel time, 2 It includes the link ID (connection link ID) of the link connected to each node.

  The road type information includes types such as a main road on the expressway and a ramp road for descending from the expressway to a general road. It also includes the speed limit for that road.

  Here, by distinguishing the start node and the end node for the two nodes constituting the link, the upward direction and the downward direction of the same road are managed as different links.

  The voice input / output device 4 converts the message to the user generated by the arithmetic processing unit 1 into a voice signal and outputs it. Also, a process of recognizing the voice uttered by the user and transferring the contents to the arithmetic processing unit 1 is performed.

  The input device 5 is a unit that receives instructions from the user. The input device 5 includes a hard switch such as a scroll key and a scale change key, a joystick, a touch panel pasted on a display, and the like.

  The sensors 6 to 8 and the GPS receiver 9 are used for detecting the current location (vehicle position) by the vehicle-mounted navigation device 100. The wheel speed sensor 6 measures the distance from the product of the wheel circumference and the measured number of rotations of the wheel, and further measures the angle at which the moving body is bent from the difference in the number of rotations of the paired wheels. The geomagnetic sensor 7 detects the magnetic field held by the earth and detects the direction in which the moving body is facing. The gyro 8 is configured by an optical fiber gyro, a vibration gyro, or the like, and detects an angle at which the moving body rotates. The GPS receiver 9 receives a signal from a GPS satellite and measures the distance between the mobile body and the GPS satellite and the rate of change of the distance with respect to three or more satellites to thereby determine the current position, travel speed, and travel of the mobile body. Measure orientation.

  FIG. 2 is a functional block diagram of the arithmetic processing unit 1.

  As illustrated, the arithmetic processing unit 1 includes a user operation analysis unit 41, a route search unit 42, a route guidance unit 43, a current position calculation unit 44, an information storage unit 45, and a display processing unit 46. Yes.

  The user operation analysis unit 41 receives a request from the user input to the input device 5, analyzes the request content, and controls each unit of the arithmetic processing unit 1 so that processing corresponding to the request content is executed. To do. For example, when the user requests a recommended route search, the display processing unit 46 is requested to display a map on the display 2 in order to set a destination. Further, it requests the route search unit 42 to calculate a route from the current location (departure location) to the destination.

  The current position calculation unit 44 uses distance data and angle data obtained as a result of integrating the distance pulse data S5 measured by the wheel speed sensor 6 and the angular acceleration data S7 measured by the gyro 8, respectively. Is integrated periodically to calculate the virtual current location (X ′, Y ′) that is the position after the vehicle travels from the initial position (X, Y). Further, a candidate point for the current position is obtained on a road (link) having a high shape correlation by performing map matching processing on the virtual current position using map data. Here, a plurality of candidate points may be obtained depending on the degree of matching. In that case, at the next calculation timing, a plurality of new candidate points are obtained based on the plurality of candidate points. The current position calculation unit 44 calculates the reliability of each candidate point from the degree of matching when map matching is performed. Then, the candidate point having the maximum reliability is set as a candidate point used for display (referred to as “display candidate point”). The display candidate point is a display position (car mark position) on the map. The current position calculation unit 44 periodically narrows the number of candidate points to a predetermined number according to the reliability.

  The route search unit 42 uses a Dijkstra method or the like to search for a route that minimizes the cost (for example, travel time) of a route connecting two designated points (current location, destination), and stores the information in the information storage unit 45. Remember.

  The route guidance unit 43 performs route guidance using the route searched by the route search unit 42. For example, the information on the route is compared with the information on the current location, and the voice input / output device 4 is used to inform the user by voice whether the vehicle should go straight before passing an intersection or the like. Further, the route guiding unit 43 displays the direction to travel on the map displayed on the display 2 and notifies the user of the recommended route.

  The display processing unit 46 receives map data in an area required to be displayed on the display 2 from the storage device 3, and at a specified scale and drawing method, roads, other map components, current location, destination, A map drawing command is generated so as to draw a mark such as an arrow for the recommended route. Then, the generated command is transmitted to the display 2.

  FIG. 3 is a diagram illustrating a hardware configuration example of the arithmetic processing unit 1.

  As illustrated, the arithmetic processing unit 1 has a configuration in which devices are connected by a bus 32. The arithmetic processing unit 1 includes a CPU (Central Processing Unit) 21 that executes various processes such as numerical calculation and control of each device, and a RAM (Random Access Memory) that stores map data, arithmetic data, and the like read from the storage device 3. ) 22, a ROM (Read Only Memory) 23 for storing programs and data, a DMA (Direct Memory Access) 24 for transferring data between the memories and between the memory and each device, and graphics drawing. In addition, a drawing controller 25 that performs display control, a video random access memory (VRAM) 26 that stores graphics image data, a color palette 27 that converts image data into RGB signals, and an A / D that converts analog signals into digital signals. Converter 28 and an SCI (Serial Communication Interface) that converts the serial signal into a parallel signal synchronized with the bus. ace) 29, a PIO (Parallel Input / Output) 30 that puts a parallel signal on the bus in synchronization with the bus, and a counter 31 that integrates the pulse signal.

  [Description of Operation] Next, the operation related to the calculation of the current position of the vehicle-mounted navigation device 100 having the above-described configuration will be described.

  As described above, the current position calculation unit 44 periodically obtains a candidate point for the current position and sets the candidate point having the highest reliability as a display candidate point. Further, a process for reviewing (correcting) the display candidate points is also performed.

  FIG. 4 is a flowchart of the display candidate point review process. FIG. 5 is a diagram for explaining a method of reviewing such display candidate points.

  As shown in FIG. 5, the ramp road is normally curved, and thus is composed of a plurality of links with a short distance. Such a link is sometimes referred to as a “sublink”, but will be described simply as a “link” below.

  The review process of the display candidate points as shown in FIG. 4 is performed in order to accurately determine whether or not the vehicle traveling on the main highway has got off the ramp road. Therefore, the current position calculation unit 44, as shown in FIG. 5, when the display candidate point 511 that has been on the main highway 510 so far has moved onto the ramp road 520 (see the display candidate point 521 in the figure). Do this flow. This flow is started every time the obtained display candidate point arrives at the start point of the link. On the other hand, if the vehicle has traveled a predetermined distance after the display candidate point has passed through the branch, the flow is stopped.

  First, the current position calculation unit 44 follows a link in front of the link where the display candidate point exists (the traveling direction of the vehicle). Specifically, the connected links are selected in the order closest to the link where the display candidate point exists (S101).

  Then, the current position calculation unit 44 determines whether or not the traced link is branched (S102). If it is branched (Yes in S102), the process proceeds to S104.

  On the other hand, when the link is not branched (No in S102), the link is traced until a predetermined number of links (Nmax, for example, 5) are traced.

  Next, the current position calculation unit 44 determines whether or not a predetermined number (Nmin, for example, 4) of links has been traced (S104). If the trace has not been completed (No in S104), the display candidate point is determined. End the review process. Note that Nmin <Nmax.

  On the other hand, when the predetermined number (Nmin) of sub-links has been traced, the current position calculation unit 44 obtains the perpendicular bisector of each link traced as indicated by the broken line in FIG. 5 (S105). ).

  Further, the current position calculation unit 44 obtains intersections of the respective perpendicular bisectors, averages the obtained positions of the intersections, and obtains a center O of a circle having a ramp road curve as a circumferential fragment. Then, a distance r from the display candidate point to the center is obtained (S106). The distance r is the curve radius.

Note that, for n links, the maximum number of intersections of the perpendicular bisectors is _{x 2} , and the center O is obtained by averaging these coordinates (x, y). However, vertical bisectors that do not intersect are excluded from the calculation.

Next, the current position calculation unit 44 acquires the vehicle speed of the vehicle from the wheel speed sensor 6. Then, the centrifugal force acting on the vehicle when the vehicle travels in a circle with a radius r at the current vehicle speed is obtained. The centrifugal force is obtained by the formula: (weight m) × (vehicle speed v) ² / (radius r). The weight m is a preset value obtained by adding the weight of the vehicle and the weight of the average number of passengers.

  Next, the current position calculation unit 44 determines whether or not the vehicle can withstand centrifugal force (S108). Specifically, determination is made based on whether or not the centrifugal force obtained in S107 exceeds a predetermined allowable value of centrifugal force. The allowable value of the centrifugal force is obtained experimentally or by calculation based on whether or not the vehicle can maintain a normal traveling posture.

  When it is determined that the vehicle can withstand the centrifugal force (Yes in S108), the current position calculation unit 44 ends the display candidate point review process without changing the current display candidate point.

  On the other hand, when it is determined that the vehicle cannot withstand the centrifugal force (No in S108), the current position calculation unit 44 has the reliability next to the current display candidate point among the plurality of candidate points of the current position. A high candidate point is set as a display candidate point (S109). FIG. 5 shows the candidate point 512 as a new display candidate point in place of the display candidate point 522 so far. Note that the current position calculation unit 44 is a candidate point on the highway main line. A candidate point with the highest reliability may be selected from among the above and set as a display candidate point.

  Thereafter, the current position calculation unit 44 ends the review process of the display candidate points.

  The display candidate point review process has been described above.

  As described above, the display candidate point review process is performed every time the display candidate point arrives at the start point of the link. Accordingly, the centrifugal force is obtained each time, and the display candidate points are reviewed. On the other hand, if the vehicle travels a predetermined distance from the branch, the accuracy of the map matching is improved, so that the review process of the display candidate points is unnecessary and is not performed.

  The embodiment of the invention has been described above.

  According to the above embodiment, if the calculated centrifugal force is not realistic, the display candidate point at the current position is corrected. That is, if the calculated centrifugal force is not considered to be driving on the ramp, it can be determined that the motorway continues to travel and the display candidate points can be obtained again on the motorway main line. . Therefore, even when the expressway and the ramp road are close to each other, the current position can be accurately displayed.

  Also, a predetermined plurality of links (Nmax) are extracted, the center of the circle is obtained from the average value of the intersections of the perpendicular bisectors, and the curve radius is obtained. Therefore, a more accurate curve radius can be obtained. On the other hand, if the link is followed, it may branch off in the middle. In this case, even if it is less than Nmax, the curve radius is determined if it is equal to or greater than the predetermined number (Nmin). . By doing so, it is possible to obtain the curve radius as accurate as possible while taking into consideration the actual situation of the road.

  The present invention is not limited to the above embodiment. The above embodiment can be variously modified.

  For example, in the above embodiment, the centrifugal force is calculated by obtaining the curve radius by using the perpendicular bisector of the link. However, the present invention is not limited to this, and the curve radius (for example, “300R” for each link is previously included in the map data. Etc.) may be held. And the curve radius of the link in which a display candidate point exists may be calculated | required from map data, and the centrifugal force which acts on a vehicle may be calculated | required.

  Further, the current position calculation unit 44 may change the weight of the vehicle for obtaining the centrifugal force depending on the type (vehicle type) of the vehicle. For example, the information storage unit 45 holds a table in which vehicle types and weights are associated with each other. The current position calculation unit 44 receives an input of the vehicle type from the user via the input device 5 in advance. And when calculating | requiring centrifugal force, the weight corresponding to the kind of vehicle received from the user is selected and used.

  Further, when the calculated centrifugal force exceeds the allowable value, the current position calculation unit 44 may recalculate display candidate points for the road links with higher linearity. For example, when display candidate points are found on a road with a curve in an area where a road with a curve and a road with linearity are close to each other, the above-described display candidate point review process is performed. When the calculated centrifugal force exceeds the allowable value, a candidate point on a highly linear road is set as a display candidate point. In addition, it can be said that the linearity of the road is so high that the difference of the change of the direction of the continuous link which comprises a road is small.

  Further, when the calculated centrifugal force exceeds the allowable value, the current position calculation unit 44 may recalculate display candidate points for a link on a road having a slower speed limit. For example, if the calculated centrifugal force exceeds the allowable value, refer to the speed limit for each link stored in the map data, and other candidate points that exist on the link whose speed limit is faster than the road where the display candidate point exists Are set as display candidate points.

FIG. 1 is a schematic configuration diagram of an in-vehicle navigation device. FIG. 2 is a diagram illustrating a functional configuration of the arithmetic processing unit 1. FIG. 3 is a diagram illustrating a hardware configuration of the arithmetic processing unit 1. FIG. 4 is a flowchart of the display candidate point review process. FIG. 5 is a diagram for explaining how the display candidate points are corrected.

Explanation of symbols

100: In-vehicle navigation device,
DESCRIPTION OF SYMBOLS 1 ... Arithmetic processing part, 2 ... Display, 3 ... Memory | storage device, 4 ... Audio | voice input / output device, 5 ... Input device, 6 ... Wheel speed sensor, 7 ... Geomagnetic sensor, 8 ... Gyro, 9 ... GPS receiver,
21 ... CPU, 22 ... RAM, 23 ... ROM, 24 ... DMA, 25 ... Drawing controller, 26 ... VRAM, 27 ... Color palette, 28 ... A / D converter, 29 ... SCI, 30 ... PIO, 31 ... Counter, DESCRIPTION OF SYMBOLS 41 ... User operation analysis part, 42 ... Route search part, 43 ... Route guidance part, 44 ... Current position calculation part, 45 ... Information storage part, 46 ... Display processing part

Claims (8)

An in-vehicle navigation device,
Means for storing an allowable value of centrifugal force acting on the vehicle;
Means for obtaining the vehicle speed;
Means for determining the current position;
Curve radius acquisition means for acquiring a curve radius of a road on the map where the current position exists;
A centrifugal force calculating means for obtaining a centrifugal force acting on the vehicle from the curve radius, the vehicle speed, and a predetermined weight;
A vehicle-mounted navigation device comprising: current position correcting means for correcting the current position when the centrifugal force calculated by the centrifugal force calculating means exceeds the allowable value. In claim 1,
The current position correcting means includes
An in-vehicle navigation device characterized in that when the centrifugal force calculated by the centrifugal force calculating means exceeds the allowable value, a current position is obtained on an expressway. In claim 1,
The current position correcting means includes
An in-vehicle navigation device characterized in that when the centrifugal force calculated by the centrifugal force calculating means exceeds the allowable value, the current position is obtained on a road having a speed limit faster than a road where the current position exists. In claim 1,
The current position correcting means includes
An in-vehicle navigation device characterized in that when the centrifugal force calculated by the centrifugal force calculating means exceeds the allowable value, the current position is re-determined on a road having a linearity from the road where the current position exists. In claim 1,
The curve radius acquisition means includes
Find the intersection of the perpendicular bisectors of a given number of links ahead of the current position,
From the obtained intersection point, obtain a circle having a curve composed of the predetermined number of links as a circumferential fragment,
A vehicle-mounted navigation device characterized in that the radius of the circle is a curve radius. In claim 1,
Means for storing map data including the curve radius for each link;
The curve radius acquisition means includes
A vehicle-mounted navigation device that acquires a curve radius of a link where a current position exists from the map data. In claim 1,
Means for storing information associating the type and weight of the vehicle;
Means for receiving an input of a vehicle type;
A vehicle-mounted navigation device comprising means for identifying a corresponding weight from the type of vehicle received. An in-vehicle navigation device,
Means for storing an allowable value of centrifugal force acting on the vehicle;
Means for obtaining the vehicle speed;
Means for obtaining multiple candidate points for the current position;
Means for determining the reliability of the candidate points;
Display candidate point setting means for setting display candidate points from a plurality of candidate points;
Means for obtaining a curve radius of a road on the map where the display candidate point exists;
A centrifugal force calculating means for obtaining a centrifugal force acting on the vehicle from the curve radius, the vehicle speed, and a predetermined weight;
The display candidate point setting means includes:
When the centrifugal force calculated by the centrifugal force calculating means exceeds the allowable value, the candidate point having the next highest reliability after the current display candidate point is reset as the display candidate point.

Images