Development of Automatic Construction Technique of Underwater Structures in Unknown Disturbances by Learning Control

提出了一种新的水下结构物在未知环境扰动下的自动安装技术。研究的核心部分是学习跟踪控制器（LTC）的开发。可以控制设备和结构的弹性响应。该方法适用于在未知流场中柔性不可忽略的大型结构物的安装。所提出的LTC不仅可以在任何水深下以优异的精度安装水下结构，而且可以同时控制结构的弹性响应。该控制器由反馈控制器和前馈控制器组成，无需事先获取复杂的电流信息，通过学习由实际轨迹与目标轨迹之间的误差转化而来的未知扰动，提高了前馈控制力，使结构在最后阶段精确跟踪目标轨迹。证明了LTC的收敛条件和鲁棒性。设计了平面柔性结构和立方体刚性结构两种试验模型进行水池试验。为了验证LTC的性能和有效性，在未知流场中进行了试验，两种模型都成功地跟踪了给定的弹道并与目标对接。为了获得 *5 mm的对接精度，模型跟踪轨迹六到七次以了解干扰。未知稳定流的最大流速为0.07 m/s。弹性响应得到很好的控制，没有弹性响应的柔性模型被刺激。

A new automatic technique for installation of underwater structures in unknown environmental disturbances was proposed. Central part of the research is development of Learning Tracking controller (LTC). Elastic response of the equipment and the structure can be controlled. This method is applicable to installation of much larger structures whose flexibility can not be ignored in unknown current. The proposed LTC can install underwater structures not only in excellent accuracy in any water depth but also control the elastic responses of structures simultaneously. The presented LTC, which consists of both feedback controller and feedforward controller, can be operated without any information about current which is generally difficult and costly to be collected before operation.By learning unknown disturbances translated from the errors between the realized trajectory and objective trajectory, LTC improves its feedforward control force and makes the structure track the objective trajectory accurately in the final stage. The convergence condition and robustness of LTC was shown. Two types of experimental models, a plane flexible structure and a cubic rigid structure, were designed for basin tests. The tests were carried out in unknown current, in order to confirm the capability and effectiveness of LTC.Both of two models were successfully made track the given trajectory and docked to their targets. To obtain docking accuracy of *5 mm, the models tracked the trajectory six to seven times to learn the disturbance. The maximum speed of unknown steady current was 0.07 m/s. Elastic responses were well controlled and no elastic responses of the flexible model were stimulated.