JPH0540440A - Navigation device - Google Patents

Abstract

PURPOSE:To refer to a travel route longer than ever with the same memory capacity by efficiently using memory and storing a large number of loci with small amount of data in a navigation device which supports the operation of a mobile body such as an automobile, etc., by displaying map information and the present location information in the map information. CONSTITUTION:The navigation device provided with a measuring means 3 which measures the present location of the mobile body and generates present location data, a locus data storage means 4 which stores the present location data at every travel of constant time or constant distance as locus data, and an azimuth detecting means 5 which detects an advancing azimuth is comprised of an advancing azimuth change position decision means 6 which decides change in the advancing azimuth of the mobile body and detects an advancing azimuth change position, and a locus data compression means 7 which performs data compression on stored locus data remaining the locus data within prescribed range before and behind the advancing azimuth change position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to map information and a navigation device for displaying current position information in the map information to assist driving of a moving body such as an automobile.

[0002]

2. Description of the Related Art In navigation devices, GPS (Glob
al Positioning System) etc. to detect the current position and display the self-position that moves moment by moment on the map,
The route that has passed is stored as locus data, and the locus data is used to display the locus on a map so that the moving route can be referred to.

Conventionally, when storing the trajectory data, the data of the detected current position is sequentially stored in a ring buffer memory having a fixed storage capacity at regular time intervals or at fixed distance movements, and the amount of stored data is increased. When the number exceeds the storage capacity of the ring buffer memory, the old storage data is overwritten on the new data in order.

[0004]

Originally, in the case of leaving the past trajectory data, it is desirable to store and refer to the trajectory data over the longest possible travel route. If it is attempted to increase the number of locus data that can be obtained and to lengthen the movement path that can be referred to, it is necessary to increase the capacity of the ring buffer memory, which inevitably leads to an increase in cost and an increase in size of the device.

The present invention was devised in view of the above problems, and efficiently uses a memory to store a larger number of loci with a small amount of data so that a longer movement can be performed with the same amount of memory. An object of the present invention is to provide a navigation device that can refer to a route.

[0006]

FIG. 1 is a block diagram showing the principle of the present invention. As shown in FIG. 1, the navigation device of the present invention, as shown in FIG. 1, has a positioning means 3 for positioning the current position of a moving body to generate current position data, and a track of the current position data every time a fixed time or a fixed distance moves. In a navigation device that includes a locus data storage unit 4 that stores data and a heading detection unit 5 that detects a heading, and at least a map information and a current position on the map, a detection signal from the heading detection unit 5 is used as a detection signal. On the basis of the moving azimuth change position determining means 6 that determines whether the moving azimuth of the moving body has changed and detects the moving azimuth change position, and a predetermined range before and after the moving azimuth change position with respect to the stored locus data. And a locus data compression means 7 for compressing data while leaving only locus data.

In the figure, 1 is a map information storage means which is a database of map information, 2 is the current position data from the positioning means 3, and corresponding map information is obtained from the map information storage means 1 to obtain the map information. And display means for displaying the current position.

[0008]

In the navigation device of the present invention, the locus data storage means 4 periodically stores the current position data generated by the positioning means 3 as locus data, and the traveling azimuth change position determination means 6 uses the azimuth detection means 5 of the azimuth detection means 5. The change in the traveling direction of the moving body to be detected is monitored. When the traveling direction of the moving body changes by a predetermined angle or more, it is determined that the traveling direction has changed, and the position where the traveling direction has changed is detected by the positioning means 3. On the other hand, the locus data compression unit 7 selects locus data within a predetermined range before and after the traveling azimuth change position determined by the traveling azimuth change determination unit 6 from the locus data stored in the locus data storage unit 4. Then, the data is compressed and stored so that only the selected locus data remains.

For example, when the intersection is curved by moving on the road, only the position of the intersection and the trajectory data before and after the intersection are stored. On the other hand, in the reproduction of the trajectory based on the stored data, the intersection position and the trajectory data before and after the intersection are used to identify the intersection in the map information, the road to reach the intersection, and the road that has progressed after passing the intersection. , The trajectory is reproduced.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram of a vehicle-mounted navigation device that is an embodiment of the present invention.

As shown in FIG. 1, the navigation system of the present embodiment has a GPS receiver 20 for receiving radio waves to measure its own current position, a geomagnetic sensor 21 and a running sensor 22 which are self-contained positioning means. A CD-ROM 23 that is a database of map information, a CD-ROM driver 24 that reads information from the CD-ROM, and a CRT (Cathode Ray Tube) 2 that displays a map and other information.
5 and a panel switch 26 that constitutes an operation input switch
And a controller 27 that controls the entire apparatus.

The GPS receiver 20 generates current position data of latitude and longitude by GPS (Global Positioning System) which receives signals from satellites. The geomagnetic sensor 21 detects the traveling direction of the vehicle by geomagnetism, and the traveling sensor 22 detects the vehicle speed, traveling distance, and the like. Controller 27
Is an MPU (Microprocessor Unit), ROM (ReadOn
ly Memory), RAM (Random Access Memory), non-volatile RAM backed up by a battery, and the like, and the non-volatile RAM is provided with a ring buffer which is a storage area of locus data.

In the above structure, the controller 27 is G
The current position data generated by the PS receiver 20 is obtained, the map information corresponding to the current position is read from the CD-ROM 23 via the CD-ROM driver 24, and the read map information and the current position mark are displayed on the CRT 25. To do. Then, the current position data is periodically obtained, and the current position mark and the current position map are updated with the movement of the own position. In addition, by the input instruction from the panel switch 26,
Read various information other than maps from the CD-ROM 23 C
Display on RT25.

Further, the controller 27 serves as a locus data storage means when the vehicle is running, and the GP is operated at regular intervals.
The current position data estimated from the data from the S receiver 20 and the travel sensor 22 is obtained, and the current position data is sequentially stored as locus data in a ring buffer provided in the nonvolatile RAM. At the same time, the detection signal of the geomagnetic sensor 21 is input as the traveling direction change position determination means at regular intervals to monitor the change in the traveling direction. In the monitoring, when the change of the traveling direction becomes a predetermined angle or more, it is determined that the vehicle has changed the traveling direction, that is, a curve, and the current position data at that time is determined by the GPS receiver 20 and the traveling sensor 22.
The current position data is stored in the non-volatile RAM as locus data.

FIG. 3 shows a processing flow chart as the trajectory data compression means performed after the controller 27 determines the change of the traveling direction. Further, FIG. 4 shows an explanatory diagram of data compression. In FIG. 4, (A) shows that the car is on the road
A route diagram in which the routes indicated by “○ ×” are moved from the bottom to the top of the drawing is shown. (B) is an explanatory view of the storage state of the trajectory data in the ring buffer in the movement shown in (A), in which the storage state before data compression is shown, and in the storage state after data compression is shown.

Processing as the locus data storage means and locus data compression means of the controller 27 will be described with reference to FIGS. 3 and 4. In FIG. 4, when moving from road a to road b, the controller 27 determines that a curve is made at a point b, and the passing position data of positions a to b to c before and after that is used as locus data and addresses 0 to 0 of the ring buffer.
4 and the address 5 is set in the first end pointer. Subsequently, the locus data of the respective passing points of d to e and f in the movement on the road B are sequentially written in the ring buffer. Then, it is determined that a curve is made at the right turn at the intersection g of the roads B and C. The process after the curve determination will be described in detail with reference to the flowchart of FIG. 3. Steps S1 and S2: After writing the trajectory data in the ring buffer, it is checked whether or not a predetermined time has passed after passing through the curved intersection. That is, it is checked whether a predetermined number of locus data has been written after the curve. If the writing of the predetermined number of locus data has not been completed, the process proceeds to step S6 and the write pointer is updated to prepare for writing the next locus data.

Step S3: When the writing of the predetermined number of locus data is completed, the last write address of the ring buffer is set in the second end pointer. This processing will be described with reference to FIG. 4. After the locus data is stored up to the address 16 of the ring buffer from the right-turning intersection g to the point h after a predetermined time, the last address 16 is stored in the second end pointer. Is set.

Step S4: Next, the locus start point is set. The locus start pointer is set to the storage address of the locus data at the point where a predetermined value is subtracted from the second end pointer. That is, as shown in FIG. 4, the storage address 12 at the point f is set so that the same number of pieces of locus data as the number of pieces of locus data from the intersection g to the point h can be secured before the intersection g.

Step S5: Then, the data from the locus start point to the second end pointer is transferred to the area of the ring buffer from the first end point to compress the data. FIG. 4B is before compression, and the data of addresses 12 to 17 are transferred to the area from address 5. FIG. 4B shows the state after compression. That is, as shown in the same figure, the locus data f before and after the next curved point g immediately after the storage area of the locus data a to c before and after the previously curved point b.
~ H is stored, only the trajectory data (○ mark) before and after the curved point is left, and the trajectory data d ~ e (×)
Mark) is erased. After the transfer, the address 10 of the area to be stored next is set in the first end pointer,
Similarly, locus data is collected from the next curve point j to a point k where a predetermined time has elapsed, and locus data i to k before and after the curve point j are collected.
Only the compressed remains.

As described above, in this embodiment, it is determined whether or not the vehicle has changed the traveling direction, and when the traveling direction is changed, data compression is performed so that only a certain number of locus data before and after the change point is stored. Is going. As a result, it is not necessary to store the trajectory data of most of the routes between the intersections whose traveling directions are changed, so that a longer trajectory can be stored with the same capacity of the ring buffer. When referring to the travel route based on the stored trajectory data, the trajectory data before and after the intersection can identify the road between the curved intersections, and thus the traveled route can be easily reproduced.

In the above embodiment, the geomagnetic sensor is used as the direction detecting means to detect the direction.
The traveling azimuth may be detected by a change in the current position data generated by the GPS receiver which is a positioning means.

Although the trajectory data is compressed every time the curve position is detected, the present invention is not limited to this. For example, the trajectory data and the heading change position can be stored up to the storage capacity of the ring buffer. However, the compression processing may be collectively performed when the data is stored in all the storage capacities. Further, the compression processing may be performed at the time of transferring the trajectory data to another medium or after the transfer.

[0023]

As described above, in the navigation device of the present invention, the trajectory data is compressed so as to store only the trajectory data within a certain range before and after the point where the traveling azimuth has changed, and the trajectory is stored with a small data capacity. Can be stored, the use of the memory is made efficient, and a longer moving path can be referred to with the same memory capacity as the conventional one.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is a configuration diagram of a vehicle-mounted navigation device that is an embodiment of the present invention.

FIG. 3 is a flowchart of a trajectory data compression process in the embodiment.

FIG. 4 is an explanatory diagram of storage and compression processing of trajectory data according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Map information storage means 2 ... Display means 3 ... Positioning means 4 ... Locus data storage means 5 ... Direction detection means 6 ... Curve position determination means 7 ... Locus data compression means 20 ... GPS receiver 21 ... Geomagnetic sensor 22 ... Running sensor 23 ... CD-ROM 24 ... CD-ROM driver 25 ... CRT 26 ... panel switch 27 ... controller

Claims (1)

[Claims] 1. A positioning means for positioning the current position of a moving body to generate current position data, and a locus data storage means for storing the current position data as locus data every time a fixed time or a fixed distance moves. A navigation device that includes an azimuth detecting unit that detects a traveling azimuth, and displays at least the map information and the current position in the map, based on the detection signal by the azimuth detecting unit, determines whether the moving azimuth of the moving body has changed. A traveling azimuth change position determining means for making a determination and detecting the traveling azimuth change position, and a trajectory data compression means for compressing the stored trajectory data by leaving only the trajectory data in a predetermined range before and after the traveling azimuth change position. And a navigation device.