波浪干扰下固定双桨无人水面艇的路径跟踪方法

无人水面艇在路径跟踪过程中容易受到波浪环境的干扰，针对该问题提出一种基于可变船长比的直线路径跟踪方法。首先，建立了固定双桨无人水面艇在二阶波浪力下的运动模型；根据视距导航原理，设计了跟踪期望航向角的PD控制器，通过融合路径方向，距离偏差及船长比等信息，实时调整左右两侧推进电机的控制电压，实现无人水面艇直线路径跟踪。然后，针对不同船长比对直线路径跟踪的影响，在PD控制器中增加了以跟踪过程中的距离偏差和距离偏差变化率为输入，以船长比为输出的模糊推理模块，对船长比进行实时在线调整，提高了系统的抗波浪干扰性能。仿真结果表明,较之固定船长比的路径跟踪方法，所提方法使跟踪过程具有更好的动态性能，并且可减小波浪干扰下的路径跟踪偏差，有效克服波浪的干扰作用。

Path tracking method of unmanned surface vehicle with two fixed propellers under the wave disturbance

In order to combat the wave disturbance that may occur when the Unmanned Surface Vehicle(USV) tracks the path, this paper proposed a straight path following method based on variable ship length rate. At first,it established a mathematical model of the USV with two fixed propellers under the second-order wave disturbance, and designed a PD controller based on the principle of Line of Sight(LOS), which can adjust the control voltage of the left and right propulsion motor timely, so that the USV can follow the straight path through fusing ship length rate, path orientation, distance error. Then, according to the influence of ship length rate on straight path tracking, it added a fuzzy reasoning module whose output is ship length rate and whose inputs are the distance error and the derivative of distance error to the PD controller,which is used to adjust ship length rate so as to improve the performance of resisting wave disturbance. Simulation results show that the proposed method not only has better dynamic performance, but also can reduce the following error under the wave disturbance and overcome wave disturbance effectively compared with path tracking method with fixed ship length rate.