Data processing: vehicles – navigation – and relative location – Navigation – Employing position determining equipment
Reexamination Certificate
1998-03-19
2001-03-20
Nguyen, Tan (Department: 3661)
Data processing: vehicles, navigation, and relative location
Navigation
Employing position determining equipment
C702S094000, C342S358000
Reexamination Certificate
active
06205401
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to navigation systems for vehicles. More particularly, the present invention pertains to navigation systems for land vehicles.
DESCRIPTION OF THE PRIOR ART
It is known to equip vehicles with navigation systems that allow position and direction to be determined. So-called strapdown inertial systems, equipped with vehicle-fixed inertial sensors, have been employed for this purpose. Accelerometers and gyros dedicated to the axes of a vehicle-fixed Cartesian coordinate system are normally employed as the sensors. The coordinate system axes in such cases are defined so that an x axis and a y axis lie in the horizontal vehicle plane, while a z axis coincides with the vertical axis of the vehicle. Typical applications of such inertial systems are found in integrated navigation systems, inertial navigation systems and track/attitude reference systems. In a commonly-employed track/attitude calculation, track/attitude information relating to the vehicle is determined (e.g. a direction cosine matrix) by means of the gyros assigned to the individual coordinate system axes. A dead reckoning navigation can be calculated in a known manner by associating the direction cosine matrix to measured vehicle-fixed velocity. The vehicle-fixed velocity measurement in such case is also employed as an augmenting measurement for determining vehicle attitude. The vehicle track and position determined in such a way are interpreted with augmenting information that may only be available to a limited extent. For this purpose, the vehicle may be equipped with receivers for satellite navigation systems (e.g. GPS) that make velocity and/or position measurements available. Alternatively, position coordinates from maps can also be used for augmentation as it is irrelevant for such applications whether the position information is obtained from a digital map or from a paper map. Employing such augmenting information, position and velocity measurements can be compared with the signals derived from autonomous on-board measurements and the difference signals supplied as observations to a Kalman filter that contains a linearized model of the algorithms for calculating the navigation data for the navigation system. The Kalman filter is employed to estimate corrections for the navigation parameters and for calibration of the navigation system sensors.
As a result of the non-linearity of the track/attitude calculation of the navigation system on the one hand and the linear approximation in the model equations of the Kalman filter on the other hand, estimates may be subject to errors when the filter is operated beyond the permissible linear operating range.
SUMMARY OF THE INVENTION
The present invention addresses the foregoing and other disadvantages of the prior art by providing an improvement in a navigation system for a vehicle. The navigation system is of the type having at least one single-axis gyro for the vehicle vertical axis, x and y axis accelerometers in the horizontal vehicle plane, a vehicle-fixed velocity measurement device and an augmentation device, especially a satellite navigation receiver and/or a map device supporting position and/or velocity of the vehicle, and a controller employing a suitable Kalman filter to connect the calculated vehicle position and/or direction of travel from measured signals. The measured signals are supplied from the augmentation device and stored.
The improvement provided by the invention includes at least one partial filter assigned to the Kalman filter. Such partial filter comprises a first partial filter for dynamic levelling and a second partial filter which, as a position filter, provides track calibration, position calibration and sensor calibration.
The advantage of this filter structure is the reduction of systematic errors implied by the reduced sensor computation (i.e. the lack of x and y gyros in the horizontal plane.
The preceding and other features and advantages of this invention will become further apparent from the detailed description that follows. Such description is accompanied by a set of drawing figures. In the drawing figures numerals, corresponding to numerals of the written description, indicate features of the invention with like numerals referring to like features throughout both the written description and the drawing figures.
REFERENCES:
patent: 3702477 (1972-11-01), Brown
patent: 5166882 (1992-11-01), Stambaugh
patent: 5416712 (1995-05-01), Geier et al.
patent: 5452211 (1995-09-01), Kyrtsos et al.
patent: 5606506 (1997-02-01), Kyrtsos
patent: 5740048 (1998-04-01), Abel et al.
patent: 5902351 (1999-05-01), Streit et al.
patent: 3229819 (1984-02-01), None
patent: 0161668 (1985-11-01), None
patent: 0496508 (1992-07-01), None
Pickhard Friedhelm
Wick Detlev
Litef GmbH
Nguyen Tan
Tran Dalena
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