An Integrated Simulation Model and Weight-on-Bit Control for Autodriller System

In petroleum drilling, conventional automatic drilling systems still rely heavily on manual intervention, which often leads to poor stability, limited multivariable coordination, and large fluctuations in drilling pressure. To address this problem, this study develops a hydraulic drawworks-based autodriller system with integrated power, drive, actuation, and control units, and establishes a mechanical-hydraulic-control co-simulation model for the coordinated regulation of drill-string hoisting speed and surface weight-on-bit (SWOB). Based on this platform, a dual-loop control framework is developed in which the inner loop uses linear active disturbance rejection control (LADRC) for rapid disturbance estimation and compensation, while the outer loop uses PID control for tracking regulation. Feedforward compensation is introduced to handle predictable load variation, and PSO-assisted fuzzy tuning is used to improve adaptability under varying operating conditions. Simulation results show that, compared with conventional cascaded PID control, the proposed controller reduces drawworks speed and SWOB overshoot by 12.5% and 40%, respectively, while the corresponding settling times are shortened by 1.805 s and 2.443 s. Prototype experiments on a scaled test platform further show that the proposed controller can be implemented on physical hardware and can maintain stable real-time regulation under laboratory conditions. These results support the feasibility of the proposed framework for coordinated hydraulic drawworks control under the simulated and laboratory-scale conditions considered in this study.