Modeling and Three-Layer Adaptive Diving Control of a Cable-Driven Underwater Parallel Platform

This paper focuses on the modeling, diving controller design, and experiment of a special cable-driven underwater parallel platform with eight-cable coupling drive structure. Kinematic and dynamic models of the platform are established utilizing a simplified approach, and the hydraulic driven control model is derived based on joint-space method. To improve the diving control precision and system robustness despite the complex dynamic behaviors and manifold unknown disturbances, a three-layer adaptive diving control strategy is proposed. Among the three control layers, layer 1 is responsible for dive planning and online monitoring, layer 2 places emphasis on synchronous control by employing an improved relative coupling strategy, layer 3 utilizes an adaptive radial basis function neural network-based backstepping sliding mode control algorithm (ARBFNN-BSMC) to achieve high precision speed control of the single driving branch. Hardware-in-the-loop simulations and experimental results illustrate that the proposed three-layer adaptive diving control strategy can asymptotically drive the cable-driven underwater parallel platform onto a predefined diving trajectory with favorable precision, robustness, and stability.