Schematic view of the cutting process of a drill bit
Recently, detailed analysis of pre-existing experimental data (Black, Walker, Tibbits & Sandstrom, 1986), has revealed that friction forces resulting from a drilling process are independent of the angular velocity of the drillbit. How to explain, in this context, the field observations that the bit was subject to a velocity-dependent torque? Further investigation of the experimental data show (Richard, Germay, & Detournay, 2007):
This project aims at focusing on the analysis and corresponding control of this very new model accounting for the torsional instabilities occurring for drilling processes. The control objective is to suppress, or at least reduce, the unwanted stick-slip oscillations. It proposes to develop three different Work Packages, following a standard control approach consisting of three steps: