Suppressing torsional drill-string vibrations considering high- and low-frequency disturbances by model reference...

This paper develops a torsional drill-string vibration suppression method based on model reference adaptive control and equivalent-input-disturbance considering high- and low-frequency disturbances. Most existing studies treat the bit-rock interaction merely as an undifferentiated external disturbance and achieve vibration suppression by compensating for it as a whole. However, they often fail to specifically address or decouple the distinct high-frequency and low-frequency components inherently present within the complex disturbance generated. To address this gap, this paper establishes a torsional vibration model of the drill-string. Then, a control scheme for torsional drill-string vibration based on the model reference adaptive control with equivalent-input-disturbance (MRAC-EID) method is developed. The state-dependent low-frequency bit-rock interaction disturbance is suppressed through the MRAC method, and the higher-frequency disturbance caused by the segment flexible characteristics of the drill-string is suppressed through the EID method. The stability analysis of the torsional drill-string vibration suppression system is conducted. Finally, the effectiveness of the developed MRAC-EID method is verified through simulation and micro-rig experiments, showing that the developed method achieves vibration suppression under different formations.