针对欠驱动无人艇位姿保持控制中无法同时兼顾位置和首向角约束的问题,提出了基于航向约束的位姿保持制导策略.首先建立了以无人艇期望位姿为原点的固定坐标系,并将坐标系划分为3个区域:可到达区域A、B和不可到达区域C.在可到达区域内无人艇可依靠前向运动和转首运动回到期望位姿,避免因无法直接产生侧向运动导致首向角变化过大的问题.其次在不同的区域执行不同的制导策略,在制导过程中严格约束无人艇期望航向.最后由制导策略生成的期望速度和期望航向,经由控制器生成执行量,无人艇快速回到期望位姿.基于航向约束的位姿保持制导策略将航向约束由内环控制纳入外环制导,无人艇在不同区域执行不同的制导策略,生成的位姿期望与内环控制相结合,实现了无人艇的位姿保持.外环制导和内环控制约束相结合以兼顾无人艇欠驱动特性,同时简化了控制器设计.仿真实验证明了该制导策略的可行性和有效性.

Aimed at the problem that the position and heading angle constrains of under-actuated unmanned surface vehicle (USV) cannot be taken into account at the same time in the position and attitude maintenance control, a strategy based on course constrains for the station keeping control of USV is proposed. First, a new fixed coordinate system based on the desired position and heading of USV is established. The coordinate system is divided into the reachable regions A and B, and unreachable region C. When the USV is in reachable region, it can return to the desired position and heading while it is able to avoid exceeding the desired heading angle range due to the inability to produce a lateral motion. Then different guidance strategies in different regions are used, which strictly restrict the course angle of the USV during the guidance process. Finally, the desired velocity and course angle are generated by the guidance strategy. The controller generates the execution and the USV quickly returns to the desired position and heading. The guidance strategy based on the course constraint incorporates the course constraint from the inner control into the outer guidance. As the USV implements different strategies in different regions, the desired position and heading and the inner loop control realize the station keeping of the USV. The outer loop guidance and inner loop control constraints are combined to take into account the under-actuated characteristics of the USV, which also simplifies the complexity of the controller design. The simulation experiments have proved the feasibility and effectiveness of the guidance strategy.