基于改进积分视线导引策略的欠驱动无人水面艇路径跟踪

路径跟踪控制是无人水面艇（USV）自主完成各项任务使命的关键技术之一，受到国内外运动控制领域的普遍关注。为提高风浪流等外界环境干扰下，无人水面艇（USV）路径跟踪控制的准确性和鲁棒性，研究海流等外界扰动环境下一类非对称欠驱动无人水面艇的路径跟踪问题，提出了2种改进积分视线（ILOS）导引策略，并基于改进导引策略和反馈控制思想实现了无人水面艇水平面的路径跟踪。与传统ILOS导引策略相比，第1种改进策略具有变积分增益能够避免积分饱和及超调现象；第2种改进策略在前者的基础上将前视距离设计为时变量，使得无人水面艇操纵更加灵活，其中积分增益和前视距离均为垂直距离误差的不同函数，引导无人水面艇灵活快速地跟踪期望路径。基于级联系统理论证明了当所有控制目标实现时，控制系统为全局k-指数稳定（GKES）的，理论分析和仿真实验证明了算法的有效性和先进性。 

Path following of underactuated USV based on modified integral line-of-sight guidance strategies

Path following control is one of the key technologies for unmanned surface vehicle (USV) to complete its mission,which is widely concerned by the field of motion control at home and abroad.In order to improve the accuracy and robustness of USV's path following control under the disturbance of the external environment such as wind,wave and flow,path following control problem of the asymmetry underactuated USV under external disturbances such as current is discussed,and two modified integral line-of-sight(ILOS) guidance strategies are proposed.Based on the modified guidance strategies and feedback control theory,path following of the USV at horizontal level is realized.Compared to the conventional ILOS guidance strategy,the first modified strategy with time-varying integral gain can avoid integral windup and overshoot phenomenon;on the basis of the first modified strategy,the lookahead distance is designed as a time-varying element in the second modified strategy,making the USV control more flexible.In the modified strategies,integral gain and lookahead distance are all computed as different functions of cross-track error,which can conduce the USV to converge to desired path in an elegant and fast manner.Based on the cascaded system theory,the control system proposed is proved to be global k-exponential stable (GKES) when the target tasks are all achieved.The theoretical analysis and simulations show effectiveness and advancement of the proposed method.