US 12,332,324 B2
Apparatus and method for calibrating a magnetic sensor system using an inhomogeneous magnetic field source
Daniel Cichon, Erlangen (DE); and Philip Beran, Erlangen (DE)
Assigned to Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V., Munich (DE)
Filed by Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V., Munich (DE)
Filed on Sep. 22, 2022, as Appl. No. 17/950,751.
Claims priority of application No. 102021210552.1 (DE), filed on Sep. 22, 2021.
Prior Publication US 2023/0090679 A1, Mar. 23, 2023
Int. Cl. G01R 33/00 (2006.01); G01R 33/02 (2006.01); G01R 33/07 (2006.01)
CPC G01R 33/0035 (2013.01) [G01R 33/0206 (2013.01); G01R 33/07 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A method, comprising:
calibrating a magnetic sensor system with a calibration apparatus comprising at least one magnetic field source and a magnetic field sensor arrangement with several individual magnetic field sensors, the calibration apparatus:
performing a plurality of individual measurements, wherein each individual measurement provides a number of measurement values depending on the number of the individual magnetic field sensors, wherein the magnetic field of the at least one magnetic field source is varied at the location of the magnetic field sensor arrangement between two successive individual measurements,
determining, based on the measurement values and by applying an optimization or estimation method, one or more unknown magnetic field sensor-specific parameters and/or one or more magnetic field source-specific parameters, wherein the determined parameters are used as correction values of the magnetic sensor system by applying these correction values to future measurement results of the magnetic sensor system,
wherein the at least one magnetic field source is configured to generate an inhomogeneous magnetic field,
wherein the magnetic field source-specific parameters and the magnetic field sensor-specific parameters each comprise a certain number of variable degrees of freedom and a certain number of constant degrees of freedom, and
wherein the method further comprises performing a minimum number of individual measurements, wherein this minimum number of individual measurements to be performed depends on
the number of the measurement values determined by the magnetic field sensors, and
the number of the variable degrees of freedom of the magnetic field source-specific parameters and the magnetic field sensor-specific parameters, and
the number of the constant degrees of freedom of the magnetic field source-specific parameters and the magnetic field sensor-specific parameters
wherein the minimum number of individual measurements is determined such that the following inequality is fulfilled:
nmess*nvar+nkonst<<ny*nmess
with
nmess: number of individual measurements to be performed,
ny: number of measurement values determined by the magnetic field sensors per individual measurement carried out,
nvar: number of the variable degrees of freedom of the magnetic field sensor-specific parameters and/or the magnetic field source-specific parameters,
nkonst: number of constant degrees of freedom of the magnetic field sensor-specific parameters and/or the magnetic field source-specific parameters.