Improved unscented Kalman filtering method for colored noises of rotary steerable system

Key words:  rotary steerable  colored noises  attitude measurement  quaternion  unscented Kalman filtering

Abstract:

In general, the measurements of three-axial accelerometers contain a great amount of colored noises, which can significantly affect the accuracy of the attitude measurement by the rotary steerable drilling system. Combined with the noise model of the three-axial accelerometer, an improved unscented Kalman filtering(UKF)algorithm based on quaternion was proposed. Based on the theory of gyroscope, the observation equation and time-varying state equation were constructed in real-time, and then the three-axis angular velocities of time-varying state equation were updated by the attitude of drilling assembly in the way of quaternion, and the UKF iterative filtering was applied. The filtering results measured from oil fields show that this method can filter the colored noises of accelerometer effectively and ensure the accuracy in the attitude measurement of rotary steerable assembly.