In this paper an approach-angle-based three-dimensional path-following control scheme has been proposed for underactuated Autonomous Underwater Vehicle (AUV) which experiences unknown actuator saturation and environmental disturbance. First, the path-following error dynamic model is derived based on the principle of relative motion which was followed by the design of approach-angle-based guidance law in both horizontal and vertical profiles of AUV to transform the three-dimensional tracking errors into heading angle and elevation angle tracking errors. The kinematic control law is designed based on the Lyapunov theory and backstepping technique. Second, the kinetic controller is designed based on the Lyapunov theory, backstepping technique and fuzzy logic system approximation method. The indirect adaptive fuzzy logic system is applied to approximate unknown smooth functions which are composed of coupled AUV hydrodynamics and complex differentials of desired pitch and yaw velocities. Moreover, the application of fuzzy control completely free from dependence on accurate AUV kinetic model. Considering a disturbance-like term, which is comprised of fuzzy logic system approximation error and bounded ocean disturbance, an adaptive law is designed to estimate the bound of it. Finally, two sets of comparative numerical simulations, including straight path following with different initial posture and spatial helix path following with sudden disturbance, are studied to illustrate the effectiveness and robustness of the proposed control scheme.

提出了一种基于未知驱动器饱和和环境扰动的欠驱动自动水下航行器的基于逼近角的三维路径跟随控制方案。首先，基于相对运动原理推导了路径跟踪误差动态模型，然后设计了在水下航行器的水平和垂直剖面上均基于进场角的制导律，将三维跟踪误差转换为航向角度和仰角跟踪误差。运动控制律是基于李雅普诺夫理论和反推技术设计的。其次，基于李雅普诺夫理论，反推技术和模糊逻辑系统逼近方法设计了动力学控制器。间接自适应模糊逻辑系统应用于近似未知的平滑函数，该函数由耦合的AUV流体动力学以及所需的俯仰和偏航速度的复数微分组成。而且，模糊控制的应用完全不依赖于精确的AUV动力学模型。考虑由模糊逻辑系统逼近误差和有界海洋扰动组成的类扰动项，设计了一种自适应律对其范围进行估计。最后，研究了两组比较数值模拟，包括具有不同初始姿态的直线路径和具有突然扰动的空间螺旋路径，以说明所提出的控制方案的有效性和鲁棒性。