Application possibilities of torque measurement variation structure to build drilling control systems
The variation structure of the torque measurement contributes to an ideal allocation of torque dynamic components on the drive motor, but precisely because of this advantage its application to control the drilling process becomes impracticable. This is due to the fact of the differentiation function presence both in the power measurement channel and angular velocity measurement channel. The function of measurement channels differentiation brings the property of cutting off the constant components of the measurement signals as well as restricts the lower frequency range up to certain values of a signal low frequencies. This leads to uncertainties like 0/<i>n</i> and <i>N</i>/0 at the structure's outlet. Use of the uncertainty of this type as control actions in the control systems is impossible, as it leads to control functions ambiguity. However, control of drilling process by the torque dynamic components is very promising. In this regard, the authors of the present article propose some solution options to eliminate the main disadvantage of the variation structure, namely, the effect of low frequency cut-off. There suggested three basic methods of uncertainties occurrence compensation when measuring torque, the application of which is determined by the specifics of each case. 1. Introduction of the initial conditions in the drilling control process. 2. Method of logical resolution of uncertainties. 3. Modernization of the variation structure based on the type of the used drive.