动力定位的分数阶双环自适应终端滑模控制

Fractional-order dual-loop adaptive terminal sliding mode control for dynamic positioning

中文关键词  分数阶  动力定位  终端滑模  双环控制  自适应控制

英文关键词  Fractional Order  Dynamic positioning  Terminal Sliding mode control  Dual-loop Control  Adaptive control

中文摘要

      为了解决具有非线性和环境干扰的船舶动力定位系统的控制问题,本文提出了一种基于分数阶双环自适应快速终端滑模控制算法,证明了闭环系统的稳定性,设计了自适应控制律,计算了滑模的收敛时间。控制系统由外环位置姿态环和内环速度环构成,外环滑模控制实现自动定位于期望位置和姿态,内环滑模控制实现对速度和角速度的定位。通过切换函数的设计,对不确定性和外加干扰具有较强的鲁棒性,避免系统出现抖振现象。对双环滑模控制器进行仿真,计算出动力定位外界环境扰动的变速运动情况下的前进位置、横荡位置、艏向角度、前进速度、横荡速度、艏向角速度、前进控制力、横荡控制力和艏向控制力矩等。对外环控制率增益λ2等参数对控制性能的影响进行了比较分析。结果表明,分数阶双环自适应终端滑模控制动态响应要稍快于传统双环控制,且超调量小,调整时间更短,所设计的控制器对有非线性和环境干扰的船舶动力定位系统都具有较强的鲁棒性。本算法为不确定性系统的变结构控制提供了新的解决方案,扩展了滑模控制算法的应用领域。

英文摘要

      In order to solve the control problems of dynamic positioning system with nonlinear and environmental disturbance, a fractional-order dual-loop adaptive terminal sliding mode control is proposed in this paper, and the stability of closed-loop system is proved. An adaptive control law is designed and the convergence time of the sliding mode is calculated. The control system consists of an outer ring for position control and an inner ring for speed control. The outer ring sliding mode control is automatically positioned towards the desired position and attitude, and the inner ring sliding mode control is used to realize the positioning of speed and angular velocity. The robustness to external disturbances and uncertainty is obtained by the design of switching function, and the chattering phenomenon in the system is avoided. The sliding mode controller is simulated. The forward position, sway position, yaw angular, forward speed, sway velocity, yaw angular velocity, heading forward input control, sway input control and yaw control torque of dynamic positioning ship are computed in the variable motion with disturbance. The influence of parameters such as outer loop control rate gain λ2 on the control effect are compared and analyzed. The results show that dynamic response of double-loop integral sliding mode control is slightly faster than the traditional double-loop control, and the overshoot is smaller and the adjustment time is shorter. The designed controller has strong robustness to the ship dynamic positioning system with nonlinear and environmental disturbance. This algorithm provides a new solution for variable structure control of uncertain systems, and extends the application field of sliding mode control algorithm.