Robust control of weight on bit in unified experimental system combining process model and laboratory drilling rig

The aim of this paper is to implement a robust weight on bit control design in an unified experimental system. A laboratory drilling rig is used to simulate the real world bit-rock interaction. Via communication between programmable logic controller (PLC) and OLE for Process Control (OPC) server, the laboratory drilling rig can exchange data with a finite element drill-string model and a hoisting system model which are realized in MATLAB/Simulink. Thus, an unified experimental system is established to reproduce the actual drilling process. The penetration resistance coefficient of the experiment rock sample is tested to obtain the bit-rock interaction model for controller design. Considering the high-order mode of the slender drill-string, a reduced order model with multiplicative weighting function is derived. Based on the developed model, a robust integrated controller is obtained by connecting a PI controller and a dynamic output feedback controller. Experiment results are presented to show the effectiveness of our method and the established system.