Three-Dimensional Path-Following Control of Autonomous Underwater Vehicles Based on the NMPC-APC Algorithm

Autonomous Underwater Vehicles (AUV) inevitably need to make three-dimensional space movements. This study addresses the challenges of rudder angle saturation constraints and model parameter perturbations in three-dimensional path-following control by proposing a hybrid control algorithm that integrates Nonlinear Model Predictive Control combined with Adaptive control (NMPC-APC). The framework comprises three phases: First, error dynamic equations for three-dimensional path-following are established based on the Serret-Frenet coordinate system, forming the foundational model for controller design. Second, an NMPC-based kinematic controller and an APC-driven dynamic controller are synergistically implemented to drive the AUV's three-dimensional path-following motion while ensuring closed-loop stability. Finally, comparative simulations against the widely-used Line-of-Sight guidance combined with Proportional-Integral-Derivative (LOS+PID) control validate the algorithm's efficacy in suppressing actuator saturation and compensating for hydrodynamic parameter uncertainties.