U.S. Philips Corporation

Henricus P Krukkert

Martinus L Thoone

In a navigation device for land vehicles the orientation signal which indicates the direction of movement along which the vehicle is moving is measured on the one hand by an electronic compass. A further orientation signal is produced by the variation of the vehicle orientation as determined by wheel sensors. These two orientation signals comprise measuring errors. In order to determine an optimum value for the orientation from said values a digital filter unit is used which comprises low-pass and high-pass filters. The value for the orientation signal measured by the compass is presented to the input of the low-pass filter and the further orientation signal is presented to an input of the high-pass filter. The filter unit further comprises a control unit which generates a filter parameter from received orientation signals and supplies said filter parameter to the low-pass filter and the high-pass filter.

Land vehicle navigation device comprising a filter unit for determining

A navigation system for a road vehicle comprises a route-determining unit and position-locating means. The route-determining unit works together with a mass memory which stores geographic data of a road network. The route-determining unit determines a driving route between a starting point and a destination supplied by the driver of the vehicle. The position-locating devices determine the vehicle position coordinates recurrently from the speed and acceleration of the moving vehicle provided by a measuring unit. A correction unit derives a correction vector for correcting the generated vehicle position coordinates. The correction vector is determined by performing a transposition of the generated vehicle position coordinates to an actual road position as repeated by coordinates of the road network stored in the mass memory. An acceleration operator is derived from the measured speed and lateral acceleration and from the generated vehicle position coordinates. The acceleration operator operates on the correction vector in order to derive a correction value for the measured acceleration. A receiver receives position coordinate signal from a navigation satellite. A Kalman filter mixes the vehicle position coordinates with the position coordinates originating from the navigation satellite.

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Eindhoven, Netherlands

Henricus P Krukkert