Backstepping design for controlling rotary drilling system

This paper develops a nonlinear backstepping design for the control of rotary drilling system, in order to arrive at a robust controller capable of dealing with the torsional oscillations (stick-slip). This work is motivated by the complex problem of the nonlinearity in drillstring, which is rotated at a constant angular velocity by an electric motor, but exhibits superimposed torsional vibrations caused by a nonlinear relationship between torque and angular velocity at the rock-crushing tool. The effectiveness of the designed controller has been tested on the rotary drilling system through numerical simulations