Boots – shoes – and leggings
Patent
1989-06-26
1991-06-04
Black, Thomas G.
Boots, shoes, and leggings
33356, 33357, 364559, G01C 1738
Patent
active
050219626
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention is based on a method for determining the north direction or the travel direction of a vehicle having an electronic compass including a magnometer fixedly arranged in the vehicle and an evaluating circuit which cyclically receives the measurement values of the magnetic field vector effective at and measured by the magnetometer and processes the measurement values to check a predetermined elliptical locus diagram and to determine parameters of the travel direction and to correct the locus diagram during a deviation of several successive measurement values from a predetermined value of the locus diagram.
Such a method for correcting the elliptical locus diagram determined for the magnetic field vector effective at the magnetometer is known from German Offenlegungsschrift 3,509,548. In this document, it is proposed to check the values of the magnetic field, measured by the magnetometer, with respect to a deviation from the determined locus diagram and in each case then to perform a correction of the locus diagram whenever deviations of the measurement values from the locus diagram exceed a particular amount several times. The disadvantageous factor in this prior art method is that the angle errors in the direction indication, occurring due to magnetic field disturbances, are corrected only very inadequately and too slowly by this method.
In a heading measuring device known from German Patent Specification 2,651,678, the magnetic field sensor is caused to switch to a further sensor for correcting angle errors during the occurrence of magnetic field disturbances, if the values measured by the magnetic field sensor deviate from a nominal value by a predetermined amount. In this prior art arrangement, it is disadvantageous that an additional sensor is needed and at least partially is influenced by the earth's magnetic field and thus by external field disturbances.
SUMMARY OF THE INVENTION
The present invention has the object of suppressing or limiting navigation errors due to interfering fields or interfering field changes acting on the magnetometer with angle disturbances occurring for a short time or longer term, to enable the direction to be indicated as accurately as possible during the disturbances and thereafter.
The method according to the invention, characterized in that, with a deviation of the measurement values from the elliptical locus diagram (0) and with a simultaneous angle change of the earth's magnetic field vector, the rate of change of the direction indicated by the compass is limited to a predetermined value and that the limiting of the rate of change of the direction indication is weighted in dependence on the duration of the measurement value deviation the characterizing the advantage of the that, when interfering fields or interfering field changes occur, the correction influence is weighted in dependence on the duration of the deviation of the measurement value from the nominal value to suppress or limit changes in the direction indication.
Advantageous further developments and improvements of the features specified in the main claim are possible by means of the measures listed in the sub-claims. For this purpose, it is particularly suitable to suppress a change in the direction indication completely with a short-time deviation of the measurement values from the elliptical circle diagram past the predetermined permissible amount. With a longer-duration deviation of the measurement values from the nominal value of the elliptical circle diagram past a predetermined amount, the rate of change of the direction indication is advantageously limited to a maximum value depending on the vehicle speed. In this arrangement, the maximum values of the change in direction, dependent on the vehicle speed, are suitably determined by means of the limit of the permissible transverse acceleration of the vehicle and these values are stored in a data memory of the evaluating circuit. At the end of the inadmissible measurement deviation, the direction of the earth's
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Helldorfer Reinhard
Kanzler Ulrich
Osterkamp Eva
Rauch Hans
Black Thomas G.
Robert & Bosch GmbH
Striker Michael J.
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