Online monitoring of the maximum angle error in AMR sensors

Anisotropic Magnetoresistance (AMR) sensors are often used for angle measurements. The sensor outputs consist of two sinusoidal signals that show undesired characteristics as offset voltage, amplitude imbalance and harmonics, which affect the angle measurements. These parameters change due to aging effects, but until now it is considered that these variations do not affect the sensor accuracy. The largest sources of angle error are compensated at the start of the sensor life but they are not monitored during its lifetime. However, the accuracy requirements are increasing and in the future, it will be necessary to verify that the sensor satisfies the accuracy despite aging. This research proposes different equations that are useful to monitor online the maximum angle error due to different sources. Based on this information it is possible to take action in order to guaranty the accuracy during the entire sensor lifetime.