Abstract: It is not an easy job to control a cylindrical and rotatable servo platform at a special angle for a push-the-bit rotary steerable drilling system while it is acted by complex applied torque. A nonlinear dynamic model is established which considers such complex torque as friction, hydraulic shock, quality distribution eccentricity, installation error eccentricity and turbine motor electromagnetic torque, etc. The regular pattern of rotational movement about this platform is obtained under no torque and complex applied torque based on simulation of this model, which relates to platform structure and torque parameters. A hydraulic driving torque test is carried out, which indicates that dynamics analysis is reasonable. Some improvement suggestions of structure design are presented.

Key words: Dynamic model, Movement simulation, Servo platform, Torque analysis