Data processing: measuring – calibrating – or testing – Measurement system – Orientation or position
Patent
1997-04-22
1998-10-27
Shah, Kamini
Data processing: measuring, calibrating, or testing
Measurement system
Orientation or position
701213, 701215, 340988, 342357, G06F 1700, G08G 10968
Patent
active
058289879
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a navigation technique for receiving wave signals from GPS (Global Positioning System) satellites so as to detect a position and an advancing direction of a moving object, such as a vehicle or a person and, in particular, to a movement detecting device which is capable of performing the autonomic navigation with high accuracy even in a place where the reception of the waves from the GPS satellites is difficult, such as in a tunnel, among high buildings or under an elevated railroad.
BACKGROUND ART
A movement detecting device has been known which detects in real time the current position and the speed of a moving object by combining a moving amount sensor for detecting a moving amount of the moving object and GPS signals received from GPS satellites, and displays them. The movement detecting device of this type has been used, for example, as a sensor unit for positional data or the like in the car navigation system. The conventional movement detecting device used in the car navigation system includes, for example, a GPS antenna and a GPS receiver for receiving GPS signals from the GPS satellites, a rotation detector of a tire as an example of the moving amount sensor, and an arithmetic unit for calculating the absolute position, the absolute speed and the absolute azimuth of a vehicle based on the GPS signals sent from the GPS receiver as well as the relative speed and the traveled distance of the vehicle based on the revolution speed of the tire measured by the rotation detector, and correcting the absolute position and the like based on the calculation results. The car navigation system prestores map data and displays the calculation result data of the arithmetic unit as superposed on the map.
In the movement detecting device thus structured, since the absolute position, etc. of the vehicle can be derived based on the GPS signals and further the speed and the traveled distance of the vehicle can be derived from the revolution speed of the tire measured by the rotation detector, it is advantageous that the movement data of the vehicle can be detected more accurately than the case where only the GPS or the rotation detector is used.
However, in the conventional movement detecting device, since only the moving amount sensor can work in a place where the GPS signals can not be received, such as among buildings, in a tunnel or in a forest, the accuracy of movement data is relatively lowered. Further, in case of the car navigation system, if the tire idles during the vehicle running or the moving amount sensor idles at a contacting portion with the tire, the measurement results of the moving amount sensor differ from the actual movement data. Further, it is possible that a user can not recognize an occurrence of such a situation. Thus, there have been such occasions where the operation reliability of the movement detecting device is lowered.
Further, when using the movement detecting device in the car navigation system, the standard of signals to be used in the rotation detector as the moving amount sensor is not offered as the standard for all the vehicles. For example, when the shapes or the sizes of the tires or the mounting portions are different, a difference is caused in measurement results. Accordingly, there has been a problem that it is essential upon installing the system to alter the vehicle so as to match the signal standard of the rotation detector or calibrate the rotation detector per vehicle and thus the system installation cost can not be lowered.
DISCLOSURE OF INVENTION
For achieving the foregoing object, the present invention provides a movement detecting device comprising GPS arithmetic means for producing first movement data based on GPS signals, the first movement data including variation components of an absolute position, an absolute speed and an absolute azimuth of a moving object; an inertia sensor for detecting an acceleration generated in a traveling direction of the moving object and an angular velocity generated about an axis
REFERENCES:
patent: 5367463 (1994-11-01), Tsuji
Miyasaka Tsutomu
Tano Michiyasu
Data Tec Co., Ltd.
Shah Kamini
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