Patent attributes
In a magnetic position detection system designed to detect a target object in a detection space using an array of magnetic sensors, the position of the target object can be determined by fitting a model of the target object's magnetic field to the sensor measurements. A robust determination of whether a target object is present can be obtained by fitting the model to the sensor measurements and determining the remaining differences between the fitted model and the sensor measurements. If the differences are high then the model is not fitting well, suggesting that the target object is not present. If the differences are low, the model is fitting well and the target object can be determined as being present. Measurements made when the target object is determined as not being present can be regarded as background field measurements including any stray fields. These stray fields can then be deducted from subsequent sensor measurements to eliminate the effect of stray fields and allow more accurate determination of the position of the target object. A user indicator may be included to indicate whether stray fields are not present, or present and accurately detected, or whether stray fields are varying.
