中文摘要：

针对具有模型不确定性和输入饱和的欠驱动自主水下航行器（AUV）,提出一种基于改进反步法的简单实用三维空间曲线路径跟踪鲁棒控制器。在Serret-Frenet坐标系下建立了空间曲线路径跟踪误差模型,结合视线角制导和虚拟向导法,设计了基于李雅普诺夫理论和改进反步法的运动学和动力学控制器。不同于传统的积分器反步法,该方法在控制器设计中采用跟踪误差的积分来增加控制器的鲁棒性,不会增加系统的状态变量和计算量;针对设计的运动学控制器存在非因果现象的问题,借助动力学模型求解出运动学控制器表达式;针对传统反步法存在的＂微分爆炸＂现象及动力学控制器过于复杂的问题,采用非线性跟踪微分器对控制器进行简化。仿真结果表明：采用所设计的基于改进反步法的控制器能够实现欠驱动AUV在模型参数不确定性和输入饱和作用下的三维空间曲线路径跟踪控制,控制精度和鲁棒性明显优于常规反步法。

英文摘要：

Based on the modified back-stepping technique,a simple and robust spatial curvilinear path following controller for the underactuated autonomous underwater vehicles（ AUVs） with model uncertainties and input saturation is presented. A path following error dynamics model is constructed in a moving Serret-Frenet frame,and the kinematic controller and dynamic controller are developed based on line-ofsight（ LOS） guidance algorithm and virtual moving target method. Differing from the traditional integrator backstepping technique,the proposed method is to introduce the integral tracking errors into the controller design to improve the robustness against the uncertainties. The dynamic model is used to solve the non-causal form caused by the coupled underactuated degrees. The nonlinear tracking differentiators（ NTDs） are employed to construct the numerical solution of differential virtual control commands to tack-le the problem of ＂explosion of terms＂in the traditional back-stepping process,and the dynamic controller expressions are simplified. Simulations demonstrate that the designed controller realizes the spatial curvilinear path following control of underactuated AUV with model parameter uncertainties and input saturation,and its accuracy and robustness are more excellent than those of the traditional back-stepping control.