JPH0510774A - Navigation device - Google Patents

Abstract

PURPOSE:To enable displaying of an uninterrupted track by using information from an acceleration sensor and a geomagnetism sensor when there is no signal from a global position measuring system (GPS). CONSTITUTION:If reception signals from a GPS receiver 2 are interrupted, a control portion 3 switches a system to that using an acceleration sensor 4 and a geomagnetism sensor 5 and sends inputs to a display portion 6 or performs control such as reading from and storing into a map storage portion 7. The acceleration sensor 4 samples acceleration by means of a piezoelectric element. The output of the piezoelectric element is integrated by time whereby velocity is found. The velocity is integrated so that distance is found. This output is synthesized with the output of the geomagnetism sensor 5 so that the relative position of an automobile is found. However, the accuracy of control is deteriorated by the double integration performed to find the distance but in the case of short distances the control is sufficient as that for correcting the GPS. Also, the navigation device can be miniaturized and there is no necessity of sampling signals from portions of an automobile such as tyres and so modification of the automobile is unnecessary.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a navigation device.

[0002]

2. Description of the Related Art Global Positioning System GPS (Global)
The Positioning System is a global navigation system using artificial satellites developed by the US Department of State. Currently, automobiles, ships, aircraft, etc. are receiving signals from satellites and using them. This system is composed of 24 satellites including the standby unit, and by using 3 of them, two-dimensional positioning is possible.
In addition, three-dimensional positioning is performed using four pieces. But GP
Since S uses SHF radio waves, it often becomes unreceivable due to attenuation or blockage due to tunnels, valleys of buildings, rainfall, cumulonimbus, etc. Also, there are no satellites at this time, so accuracy is good. However, there are various problems in using it in a car. In addition, the life of satellite solar cells is short,
There is also a problem that the strength of the radio wave weakens and transmission becomes impossible. In addition, in a navigation system that uses self-contained navigation using a geomagnetic sensor and a distance sensor that uses tires, it is necessary to modify the vehicle because it is necessary to take data from the tires. Also, since this distance sensor is fixed to the vehicle, this system cannot be used in vehicles without a distance sensor. On the other hand, the self-contained navigation using the acceleration sensor is inferior in accuracy to the distance sensor using the tire and is not generally used at present.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
Since the navigation system using S uses SHF radio waves, it cannot be received in tunnels or in the valleys of buildings.
During this time, when the trajectory of the vehicle cannot be displayed on the display unit and the GPS receiver receives a signal again, there is a problem that the map on the display unit is switched and the usability is poor. It is an object of the present invention to provide a navigation device capable of obtaining an uninterrupted trajectory even when the GPS receiver cannot receive. In addition, it is a portable and accurate navigation.
Is to obtain an optional system.

[0004]

[Means for Solving the Problem] GP for outputting absolute position
An S receiver, a geomagnetic sensor for finding the direction, an acceleration sensor for finding the distance, a map storage unit for storing and storing map information, and a display unit for displaying the map information read from the map storage unit, A GPS receiver or a geomagnetic sensor and an acceleration sensor are used to select information according to the arrival of radio waves, and a control unit for controlling a display unit, a map storage unit, etc. is provided. When not present, the information from the acceleration sensor and the geomagnetic sensor is used.

[0005]

According to the present invention, two systems, G
It has both a system using PS and a system using a geomagnetic sensor and an acceleration sensor. When GPS cannot be received, another system supplements the path of the vehicle to display an uninterrupted path on the display unit.

[0006]

1 is a block diagram showing an embodiment of the present invention and FIG. 2 is an external perspective view of a navigation device. In the figure, reference numeral 1 is an antenna for receiving GPS radio waves from satellites, and in order to perform positioning by GPS, radio waves from four satellites must be received at the same time. It is not possible to use a strong antenna having a large gain, and generally, a plane antenna such as an orthogonal dipole antenna, a helical antenna, or a microstrip antenna is used.
Reference numeral 2 denotes a GPS receiver, which processes GPS radio waves obtained from the antenna inside the receiver and outputs the absolute position of longitude and latitude.
When a reception signal from the GPS receiver 2 is interrupted by a control unit 3, the system is switched to a system using an acceleration sensor 4 and a geomagnetic sensor 5 described later and input to the display unit 6, or is read from the other map storage unit 7. Controls storage and storage. In the geomagnetic sensor 5, a toroidal ferrite core is provided with a set of detection coils orthogonal to the exciting coil, and the change in the magnetic flux generated by the exciting coil due to the external magnetic field is extracted by the detecting coil to display the direction.

The acceleration sensor 4 takes out acceleration by a piezoelectric element. When the acceleration is felt, the piezoelectric element is deformed. A voltage is generated by the piezo phenomenon according to this deformation. The acceleration sensor 4 obtains the speed by integrating the output of the piezoelectric element with time. The velocity is further integrated to show the distance. The relative position of the vehicle can be obtained by combining this output and the output of the geomagnetic sensor 5. However, since the distance is obtained by double integration, the accuracy is deteriorated. However, a short distance is sufficient for GPS correction. Further, it has a merit that it can be made compact and there is no need to take a signal from a car part such as a tire, so that it is not necessary to modify the car. A display unit 6 reads a necessary map 12 in response to a signal from the control unit 3 and displays the current position on it. Liquid crystal plate (LC
Use D). If you don't care about the size, you may use a CRT. Reference numeral 7 is a map storage unit, which is a CD-R as a medium.
The OM is used, and the CD-ROM is instructed by the controller 3.
A map 12 of a required place is output from the map data read from the display unit 6 to the display unit 6. In addition to this, an IC memory, an optical card or the like can be used as the medium. 8 is a handle. In this embodiment, since the antenna 1 and the display unit 6 can be attached and detached, they can be carried by mounting an external battery 9 and, as shown in FIG. When the case is rotatable, the case 13 can be carried around.
It can also be stored at a certain angle and can be tilted appropriately when viewing the display. Further, the display portion can be separated from the case 13 and can be connected to each other by a lead line.

Reference numeral 10 is a power supply terminal, and if only the antenna 1 is moved, the navigation device can be moved from the car A to the car B without modifying the car. The power supply terminal 10 is a cigarette
It only needs to be connected to a writer and can be used as if it were a CD radio cassette. Reference numeral 11 is a support portion of the LCD display portion.

Next, a map shown in the display portion of the present invention, FIG.
Will be described. Reference numeral 12 is a map displayed on the display unit 6. When going from the point A to the point E in FIG. 3, turn right at the point B, pass through the points C, H, I, and D to reach the point E. When there is a GPS signal, the map is switched at point I and the position is continuously displayed. Then GP at point C
When the S radio wave is cut off and the signal can be received again at the point D, the map is suddenly switched and the user is very confused. Therefore, when the radio wave becomes unreceivable at the point C as in the present embodiment, the unreceivable signal appears accordingly and the signal is switched to the signal from the geomagnetic sensor and the acceleration sensor provided with the signal. If this is done, since the distance is less integrated at point I, the map will switch to point D almost correctly at point I. At the point D, the GPS signal is switched again, but the error is small and the map movement is small, so the user will not be confused.

[0010]

As described above, according to the present invention, when the GPS receiver becomes unreceivable, a system using an acceleration sensor and a geomagnetic sensor instead of GPS is used to compensate for the locus of the map on the display unit. Can be maintained.
Therefore, if GPS cannot be received for a certain period of time and reception is possible after a while, there is no discomfort even if the map is switched. In addition, since the present invention has the antenna other than the antenna built into the case, it can be carried not only to the sea and mountains, but also to any place by attaching an external battery, and the antenna can be installed without modifying the automobile. -Navigation system can be used immediately by simply mounting it on the cable and removing power from the cigarette lighter. In addition, since the display unit is configured to be rotatable, the display unit can be tilted at an easy-to-see angle, and when it is carried, it can be stored in the case and thus easy to carry. Also, since the display unit is removable, it can be set in a place where it is easy to see.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is an external perspective view of a navigation device according to an embodiment of the present invention.

FIG. 3 is a map shown on a display unit of a navigation device according to an embodiment of the present invention.

[Explanation of symbols]

1 antenna 2 GPS receiver 3 control unit 4 Accelerometer 5 Geomagnetic sensor 6 Display 7 map storage 10 power terminals 12 maps 13 cases

Claims (3)

[Claims] 1. A GPS receiver for indicating an absolute position, a geomagnetic sensor for determining an azimuth, an acceleration sensor for determining a distance, a map storage unit for storing and storing map information, and a map storage unit for reading. A display for displaying map information, and G
Information from the acceleration sensor and the geomagnetic sensor is provided, which is provided with a control unit that selects the signal of the PS receiver and the signals of the geomagnetic sensor and the acceleration sensor, and controls the display unit, the map storage unit, and the like. Navigation device characterized by switching to 2. The navigation device according to claim 1, wherein the display unit is rotatably housed in the case. 3. The navigation device according to claim 1, wherein the display unit is removable.