Method of determining an interference-magnetic field in a motor vehicle provided with an electronic compass
First Claim
1. A method of determining an interference magnetic field component in a motor vehicle provided with an electronic compass, the compass having a fixedly mounted magnometer consisting of two probes, each probe having a horizontally arranged rod-like core of magnetisable material, the cores in respective probes including an angle of 90°
- relative to each other and each supporting a winding, means for applying an alternating auxilliary voltage to said windings to alternately magnetize said cores up to saturation, said auxilliary voltage being combined with voltages induced in said windings due to a constant magnetic field composed of an earth'"'"'s magnetic field component and an interference magnetic field component, said combined voltages producing an alternating measuring voltage, and means for evaluating the duty cycle ratio of positive and negative halfwaves of said measuring voltage, the method comprising the steps of measuring the magnitude and direction (Hg1) of the constant magnetic field in a first position of the vehicle, then measuring the magnitude and direction (Hg2) of the constant magnetic field in a second position in which the vehicle is turned around a vertical axis by 180°
, then computing from the determined values (Hg1, Hg2) the magnitude of the interference field component (Hs) according to vector equation
space="preserve" listing-type="equation">H.sub.s =1/2(Hg1+Hg2)and storing the computed Hs value for further processing.
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Accused Products
Abstract
To calibrate a electronic compass provided with a magnetometer and being fixedly mounted in a motor vehicle the magnitude, and direction of interference magnetic field must be determined. For this purpose, a constant magnetic field Hg containing an earth'"'"'s field component He'"'"' and the interference field component Hs, is measured by the magnetometer in a first position of the vehicle (Hg1) and then in a second position (Hg2) in which the vehicle is turned by 180°. From the measured constant field magnitudes and directions, (Hg1, Hg2) the interference field component Hs is calculated according to vector equation Hs +1/2 (Hg 1+Hg 2).
45 Citations
1 Claim
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1. A method of determining an interference magnetic field component in a motor vehicle provided with an electronic compass, the compass having a fixedly mounted magnometer consisting of two probes, each probe having a horizontally arranged rod-like core of magnetisable material, the cores in respective probes including an angle of 90°
- relative to each other and each supporting a winding, means for applying an alternating auxilliary voltage to said windings to alternately magnetize said cores up to saturation, said auxilliary voltage being combined with voltages induced in said windings due to a constant magnetic field composed of an earth'"'"'s magnetic field component and an interference magnetic field component, said combined voltages producing an alternating measuring voltage, and means for evaluating the duty cycle ratio of positive and negative halfwaves of said measuring voltage, the method comprising the steps of measuring the magnitude and direction (Hg1) of the constant magnetic field in a first position of the vehicle, then measuring the magnitude and direction (Hg2) of the constant magnetic field in a second position in which the vehicle is turned around a vertical axis by 180°
, then computing from the determined values (Hg1, Hg2) the magnitude of the interference field component (Hs) according to vector equation
space="preserve" listing-type="equation">H.sub.s =1/2(Hg1+Hg2)and storing the computed Hs value for further processing.
- relative to each other and each supporting a winding, means for applying an alternating auxilliary voltage to said windings to alternately magnetize said cores up to saturation, said auxilliary voltage being combined with voltages induced in said windings due to a constant magnetic field composed of an earth'"'"'s magnetic field component and an interference magnetic field component, said combined voltages producing an alternating measuring voltage, and means for evaluating the duty cycle ratio of positive and negative halfwaves of said measuring voltage, the method comprising the steps of measuring the magnitude and direction (Hg1) of the constant magnetic field in a first position of the vehicle, then measuring the magnitude and direction (Hg2) of the constant magnetic field in a second position in which the vehicle is turned around a vertical axis by 180°
Specification
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- Resources
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Current AssigneeRobert Bosch GmbH
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Original AssigneeRobert Bosch GmbH
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InventorsBauer, Harald, Hettich, Gerhard
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Primary Examiner(s)Eisenzopf, Reinhard J.
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Assistant Examiner(s)Snow, Walter E.
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Application NumberUS06/763,143Time in Patent Office965 DaysField of Search324/244, 33/356, 33/361US Class Current324/244CPC Class CodesG01C 17/38 Testing, calibrating, or co...
