欠驱动无人艇自适应滑模航迹跟踪控制

为便于航迹跟踪控制器设计和分析，引入坐标变换，建立典型的欠驱动无人艇数学模型；建立以航迹上自由点为原点的Serret-Frenet坐标系，实现对航迹跟踪误差变量的描述；通过将航迹参数的更新律作为一附加控制输入，实现了无人艇航迹跟踪控制系统由欠驱动向全驱动控制的转变，并利用改进视线导引算法实现了对无人艇位置的跟踪控制；考虑海流等外界扰动的影响，采用滑模自适应技术分别设计了无人艇航向和航速控制算法，实现了对航向角、纵向速度跟踪误差的镇定；基于李雅普诺夫理论和级联系统理论证明了航迹跟踪控制系统的一致半全局指数和一致全局渐进稳定性。仿真结果表明：所提出的控制算法可在一定程度上处理海流等外界扰动，跟踪效果良好，并且克服了角速度持续激励问题，能够同时实现对直线和曲线航迹的跟踪。
In order to facilitate the design and analysis of the tracking controller, coordinate transformation was introduced to establish a typical underactuated USV mathematical model. The Serret-Frenet coordinate system was established to describe the tracking error variables. Then, considering the underactuated system, the updated law of the tracking parameters was taken as the additional input of control, the tracking control of the USV position was realized by using the improved line-of-sight guidance algorithm. In view of the disturbance such as ocean current and so on, the adaptive sliding mode technique was used to design the heading and speed tracking control law, respectively, which realizes the stabilization of heading error and longitudinal velocity tracking error. Based on Lyapunov and cascade theory, the uniformly global asymptotic and semiglobal exponential stability of the tracking control system was proved. The simulation results show that the proposed control algorithm can deal with the disturbance such as ocean currents to a certain extent, and the tracking effect is good. Moreover, it overcomes the continuous excitation of angular velocity and can track the straight and curved line at the same time.