Dynamics and control of underwater tension leg platform for diving and leveling

This paper focuses on high-precision diving and leveling control of an underwater tension leg platform, which uses hydraulic winches as the actuation mechanism. First, dynamic model is established based on joint space. Then, decoupled double closed-loop control strategies for diving and leveling are proposed and internal closed-loop controllers are designed and tested based on backstepping sliding mode control (BSMC) method. Finally, winch tests and field trials are carried out to verify the efficacy of our approach. Simulation and experimental results show that the controllers designed in this paper can achieve speed control and displacement control with high precision and strong adaptability, thus leading to successful diving and leveling control of the underwater tension leg platform.