Lei Yunsong, Zhang Xianku, Gao Shihang, Guo Qiang
Key Lab. of Marine Simulation and Control, Navigation College, Dalian Maritime University, Dalian 116026, China.
College of Electrical and Control Engineering, Xi'an University Of Science And Technology, Xian, 710054, China.
ISA Trans. 2025 Jun;161:155-165. doi: 10.1016/j.isatra.2025.03.014. Epub 2025 Mar 31.
To enable underactuated ships to achieve trajectory tracking under unknown external disturbances, model uncertainties, and actuator saturation and dead zone, a fixed-time prescribed performance trajectory tracking control method is designed. Firstly, the position tracking errors are constrained by designing the barrier Lyapunov function, and the prescribed performance function is set as the constraint boundary to address the issue of fixed constraint boundaries in traditional methods. Secondly, RBF neural networks are employed to estimate the model uncertainties, and adaptive laws are used to estimate the upper bound of the composite disturbances. Finally, the controller is designed by incorporating fixed-time convergence theory and further using fixed-time sliding mode surface in order to overcome the shortcomings of traditional control algorithms in terms of slow response and the use of finite-time convergence with respect to the initial state. Through Lyapunov stability analysis, it is proven that all signals in the closed-loop system are bounded, and the velocity tracking errors can achieve global fixed-time convergence. Simulation results demonstrate that the proposed control scheme enables underactuated ship to achieve trajectory tracking even in the presence of input saturation and dead zone. Statistical results show that the performance indicators of the proposed controller are significantly smaller than those of the first group in the comparative experiments, with a shorter settling time. Moreover, compared to traditional saturation handling methods, the input curves of the proposed controller are smoother and more aligned with practical engineering requirements.
为使欠驱动船舶在未知外部干扰、模型不确定性以及执行器饱和与死区的情况下实现轨迹跟踪，设计了一种固定时间规定性能轨迹跟踪控制方法。首先，通过设计障碍Lyapunov函数来约束位置跟踪误差，并将规定性能函数设置为约束边界，以解决传统方法中固定约束边界的问题。其次，采用径向基函数神经网络来估计模型不确定性，并使用自适应律来估计复合干扰的上界。最后，结合固定时间收敛理论并进一步使用固定时间滑模面来设计控制器，以克服传统控制算法在响应速度慢以及对初始状态使用有限时间收敛方面的缺点。通过Lyapunov稳定性分析，证明了闭环系统中的所有信号都是有界的，并且速度跟踪误差能够实现全局固定时间收敛。仿真结果表明，所提出的控制方案能够使欠驱动船舶即使在存在输入饱和与死区的情况下也能实现轨迹跟踪。统计结果表明，在所进行的对比实验中，所提出控制器的性能指标明显小于第一组的性能指标，且调节时间更短。此外，与传统的饱和处理方法相比，所提出控制器的输入曲线更平滑，更符合实际工程要求。
