Sliding Mode Control of Rotary Drilling Systems with Parametric Uncertainty

We propose an algorithm for regulation of vertical penetration rate in rotary drilling systems for the case where parameters of the environment are unknown, and only nominal (approximate) values of the drillstring parameters are available. The algorithm is implemented in two phases: identification and control. First, we identify the values of drilling system’s parameters, and then apply them to the control scheme. The controller is based on a super-twisting algorithm, as well as several high-order sliding mode observers. The proposed approach utilizes two measurements on the lower end in the identification phase only; however, in contrast with the existing results, it does not require knowledge of any parameters except motor characteristics. Feasibility of the proposed algorithm is confirmed by simulation results.