A study on effect of geomagnetic sensor correction in various enviroments

Abstract

MEMS sensors have come to be used for various functions of smartphones and automatic driving system. The 9-axis motion sensor, which is one of the sensor modules, includes a three-axis gyro sensor, a three-axis acceleration sensor, and a three-axis geomagnetic sensor. The geomagnetic sensors which enable to measure the absolute direction are often used to estimate human posture. However, since the magnetic field is easily affected by the outside, it’s necessary to correct the sensor output. In this research, the geomagnetic sensor output is corrected using the gyro sensor output. The proposed method does not need complicated procedures. We verify the effectiveness of the proposed method even in environments where magnetic field disturbance generated, such as underground and high-rise buildings made of reinforced concrete. Furthermore, the knee joint angle during walking is estimated using the two 9-axis motion sensors by the proposed method.