US Patent 7949487 Moving body posture angle detecting apparatus

An angular velocity detected by an angular velocity sensor (10) is integrated by a small angle matrix calculator (12) and a matrix adding calculator (14), and then restored as a posture angle (angular velocity posture angle) by a matrix posture angle calculator (16). A posture matrix is calculated by a tilt angle calculator (22) and an acceleration matrix calculator (24) and an acceleration detected by an acceleration sensor (20) is restored as a posture angle (acceleration posture angle) by a matrix posture angle calculator (26). Low pass filters (18, 28) each extract a low range component, the difference between the two is calculated by a differencer (30), and only the drift amount is extracted. A subtracter (32) removes the drift amount from the angular velocity posture angle and the result is output from an output device (34). In addition, a posture angle matrix calculator (36) converts the result to a posture matrix, which it feeds back to the matrix adding calculator (14).