Objective The traditional manual control mode of a rotary steerable system (RSS) faces challenges, including response delay and low control efficiency. To address these challenges, this study proposed a closed-loop automated attitude control method for the RSS and verified its effectiveness through hardware-in-loop (HIL) simulation.
Methods This study focuses on the drilling process of a point-the-bit RSS. In the case of deviations between measured and target attitudes, the control parameters were calculated based on the deviation signals using a closed-loop controller, driving the RSS actuator to conduct trajectory correction. Afterward, the actual attitude was yielded and then entered the input end of the RSS through the feedback of the measurement unit, thereby forming a closed-loop control structure. To further validate the effectiveness of the proposed control algorithm, this study developed a HIL simulation platform consisting of (1) a digital twin model that integrated a model describing the movement of the drilling tool and a virtual attitude sensor model, (2) a real-time simulator, and (3) a physical main control unit of the RSS. This platform enables real-time interactions among the control algorithm, the movement model of the drilling tool, and the virtual attitude sensor model. In this manner, the high-precision simulation of complex downhole conditions can be achieved in a laboratory environment. Using the HIL simulation platform, this study conducted tests and experiments on manual and automated control modes of drilling, along with anti-disturbance tests on the holding interval under the control of analytical formulas and proportional integral derivative (PID).
Results and Conclusions Compared to manual control, the automated control mode exhibited significantly reduced overshoot, steady-state errors, and settling time. For the inclination interval, the automated control mode reduced the overshoot from 23.92% to 1.96% and the average settling time by 72.33% compared to the manual control model. For the azimuth interval, the automated control mode reduced the overshoot from 23.31% to 2.04% and the average settling time by 53.45%. To verify the robustness of the automated attitude control method, anti-disturbance tests were conducted under azimuthal disturbances with a mean of zero and a variance of 0.2. The results reveal that the automated attitude control method, combined with PID control, reduced the settling time by 18.9% reduction in the holding section. Therefore, the proposed closed-loop automated control method can significantly enhance the attitude control performance of the RSS, the stability of drilling trajectories, and response efficiency, providing a feasible technical pathway for achieving the automated RSS control under downhole conditions. The digital twin-based HIL simulation platform offers an efficient environment for verifying the iterative optimization of the downhole closed-loop control algorithm, effectively avoiding the high cost and risks associated with tests in the actual downhole environment. This accelerates the iterative optimization of the downhole closed-loop automation algorithm of the RSS and its transformation to engineering implementation.
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