针对环境(主要指边界信息)已知的区域搜索任务,设计了适用于欠驱动AUV(autonomous underwater vehicle)的区域搜索方案,能在极少量人工参与的情况下在任务区域的电子海图基础上实现环境模型建立进而规划出全局路径,由AUV自主地完成对路径和地形的自主跟踪,从而实施诸如地理信息采集或物体探测等作业任务.首先,路径规划方法能在给定任务参数的基础上自主地对电子海图进行处理形成环境模型并据此给出2维梳状全局路径,即使区域的几何形状为复杂的凹多边形也能给出合理结果;其次,自主跟踪采用解耦的控制方法,即分别对纵向速度、艏向和深度进行控制,使得AUV能同步地完成对水平面路径和对海底地形的跟踪.提出了一种基于Sigmoid函数的路径跟踪制导控制方法,控制器以AUV的当前艏向及其与路径的横向距离偏差作为输入,经过计算输出参考艏向角;将具有良好鲁棒性的非线性自适应S面控制算法融入执行层的控制,在加速了系统响应的同时减小了超调从而提升了控制效果;最后,跟踪仿真试验的结果显示AUV在水平面对梳状路径的跟踪误差在给定路径规划重叠率参数的前提下能保证AUV对区域扫描的全覆盖,在垂直面对地形高度的跟踪误差符合传感器对距离的要求.全局路径规划方法的可行性在介绍算法的同时结合算例得以验证,跟踪仿真试验也说明自主跟踪控制器能较好地同时跟踪梳状路径和变化的地形.
In order to accomplish region search task in a boundary information known area, a global path planning method based on electronic chart suitable for underactuated AUV (autonomous underwater vehicle) is designed. Needing only for a little amount of manual labor, target region environment model is established from corresponding electronic chart, global path planning is accomplished as well. Automatically region search task aiming at geographic information collecting or object detecting is completed after the jointly execution of path tracking and terrain tracking. Firstly, based on the given task parameters, the proposed path planning method can output a comb shaped 2 DOF global path automatically making use of electronic chart. Regardless of how complex the region shape is, even a concave polygon, the algorithm can give reasonable results. Secondly, a decoupled control method (DCM) is adopted, which means velocity, heading and depth are controlled separately. The use of DCM makes it possible to accomplish the horizontal path tracking and vertical terrain tracking simultaneously. Path tracking adopts a proposed Sigmoid function based guidance control method which outputs reference heading in use of both AUV's current heading and the transverse distance deviation between AUV and path. An adaptive S-surface control method is adopted in designing the controller of executive level. The method itself owns robustness and nonlinearity and the adoption not only speeds up system response but also short overshoot, control performance is increased as a result.Last, on the premise of given path planning coverage fraction, tracking simulation experiment results show that tracking error of horizontal comb shaped path tracking guarantees full coverage in the AUV search on mission area. What's more, terrain tracking error on vertical plane meets the requirement of vertical distance for side scan sonar. In conclusion, the feasibility of the path planning algorithm is demonstrated by the combining examples in the process