Nonlinear analysis of friction torque of steady platform control system for rotary steering drilling

The existence of non-linear characteristic of friction torque to the control axis can not be ignored in rotary steering drilling steady platform control. The causes producing friction torque in steady platform control system were analyzed step by step based on the structure of the system. The theoretical derivation and numerical analysis were performed on bearing friction torque, viscous friction torque, and pulsating friction torque in the system. The impacts of the friction torques to system were studied through experiments and simulations. Approaches to reduce non-linear effects of the friction torques were recommended. These provide a theoretical basis for control and decision-making of the steady platform.