Offset compensation for capacitive angular position sensors by evaluating the Kalman filter innovation sequence

The task of sensing angular position and angular speed plays an important role in the field of industrial applications. The main focus is on the robustness, accuracy and the ease of use, since such sensors are utilized under rough conditions. Non-contacting capacitive sensors feature very good properties in terms of insensitivity to environmental influences. Regardless of which signal processing technique is applied, segment drifts and voltage offsets during operation time have to be taken into account. This paper addresses the automatic compensation of sensor offset and sensor drift caused by temperature fluctuations or even when operating in moisty or dirty environment. The proposed method is based on the monitoring, evaluation and processing of the innovation sequence of the applied modified extended Kalman filter.