US 12,345,779 B2
Method for detecting and compensating a stray magnetic field when determining a rotation angle of a rotatable element by means of a magneto-resistive sensor system and magneto-resistive sensor system
Jean Doucement, Cordes-Tolosannes (FR)
Assigned to Hella GmbH & Co. KGaA, Lippstadt (DE)
Filed by Hella GmbH & Co. KGaA, Lippstadt (DE)
Filed on Mar. 30, 2023, as Appl. No. 18/193,272.
Application 18/193,272 is a continuation of application No. PCT/EP2020/077222, filed on Sep. 29, 2020.
Prior Publication US 2023/0258742 A1, Aug. 17, 2023
Int. Cl. G01R 33/00 (2006.01); G01D 5/14 (2006.01); G01R 33/09 (2006.01)
CPC G01R 33/0017 (2013.01) [G01D 5/145 (2013.01); G01R 33/09 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A method for detecting and compensating a stray magnetic field when determining a rotation angle of a rotatable element to which a magnetic element is attached, by a magneto-resistive sensor system comprising a first magneto-resistive sensor disposed on a first surface of a printed circuit board and a second magneto-resistive sensor disposed on a second surface of said printed circuit board opposite to said first surface, the method comprising the steps of
a) measuring a first angle of the magnetic field detected by the first magneto-resistive sensor during rotation of the rotatable element,
b) measuring a second angle of the magnetic field detected by the second magneto-resistive sensor during the rotation of the rotatable element,
c) computing an angle difference between the first angle and the second angle via a subtraction module,
d) determining a direction of rotation of the rotatable element via a rotation direction detection module,
e) computing an angle of the stray magnetic field and an amplitude of the stray magnetic field based upon the first angle measured in step a) or the second angle measured in step b), the angle difference computed in step c), and the direction of rotation determined in step d), and
f) determining a compensation angle for compensating for the presence of the stray magnetic field,
wherein a ratio is computed of (i) a stray magnetic field amplitude to (ii) the angle difference computed in step c), wherein (i) a stray magnetic field amplitude to (ii) the angle difference computed in step c) ratio is used for determining the compensation angle.