1. Field of the Invention
The present invention relates generally to a position recognizing system for recognizing the three-dimensional position of a moving object, which moves by an autonomous navigation system.
2. Related Background Art
Conventionally, there have been developed various techniques, such as movement control, path detection, route detection and location detection, for a moving object, such as an unmanned robot, a self-contained traveling work (autonomous running) vehicle and an unmanned helicopter. Among these techniques, the moving object's own position recognizing technique is one of the important techniques.
As the moving-object's own position recognizing techniques, there is a technique for detecting a two-dimensional angular velocity of a moving object, such as an autonomous running vehicle, which autonomously travels on the ground, by a vibration gyro or an optical gyro and for detecting a translation speed of the moving object by a sensor for measuring a ground speed, to calculate a moving amount of the moving object from a reference position to measure the moving-object's own position. In the case of a flying object such as an unmanned helicopter, there is a technique for detecting a gravitational acceleration to detect the acceleration of the flying object and for integrating the acceleration to recognize the moving amount of the flying object by an inertial navigation system.
Moreover, in recent years, there is adopted a technique for receiving radio waves from at least three artificial satellites, such as satellites for a global positioning system, to analyze a phase difference between the radio waves received by two GPS receivers or to analyze code communication contents (the positions of the satellites and updating time of the radio wave emission) alone, estimating the moving object's own position. In Japanese Patent Application No. 8-249061, the applicant has proposed an autonomous running vehicle, which has an improved control stability by correcting the positioning data based on travel history from a reference position on the basis of the positioning data obtained by utilizing satellites.
However, in the case of a flying object such as an unmanned helicopter, it is not only required to recognize the flying-object's own rotational and translation speeds in a three-dimensional space, but it is also required to obtain an accurate terrain clearance and a minute navigation information when the flying object flies at a low altitude.
In such a case, according to conventional systems, it is not possible to obtain a sufficient precision under the influence of drift, which causes the deterioration of the positioning precision. In addition, it is difficult to obtain an accurate terrain clearance if the flying object flies above a complex terrain. That is, the prior art is insufficient to precisely analyze a surrounding environment in a three-dimensional space to cause the analyzed results to be reflected in the navigation information.