State Feedback and Torque Feed Forward Combined Control System for Suppressing Drill-Strings Stick-Slip Vibration

Abstract

In drilling field, drill-strings stick-slip vibration is a common phenomenon and may lead to a series of drilling accidents. In order to improve drilling efficiency, this paper commits to study a new control system to suppress the undesired stick-slip vibration. In this work, a two degrees of freedom lumped parameter model is established to imitate the drill-strings. A state observer is proposed to estimate the unknown drill-strings states. A reference governor is put forward to optimize drilling parameters. In addition, in order to enhance the anti-interference ability of the closed-loop system, a torque feed forward is introduced into the control system. Based on the state observer and the reference governor, a state feedback and torque feed forward combined controller is designed. The simulation results indicate preliminarily that the designed state feedback and torque feed forward controller, compared with the drilling industry PI controller, has better dynamic performance and stronger ability to eliminate the drill-strings stick-slip vibration. Finally, the control system is applied in the drilling field. The experimental tests demonstrate that the designed controller can effectively suppress the drill-strings stick-slip vibration.

Keywords

• drill-strings
• stick-slip vibration
• closed loop control system
• lumped parameter model
• state observer
• reference governor
• state feedback control
• feedforward control
• nonlinear friction torque
• angular velocity
• damping
• dynamics
• estimation
• matlab
• nonlinear systems
• optimization
• robustness
• state estimation
• velocity control