【作者】 朱计华；

【导师】 苏玉民；

【作者基本信息】 哈尔滨工程大学 ， 船舶与海洋结构物设计制造， 2007， 硕士

【摘要】 水下机器人是一个典型的强非线性、强耦合和不确定系统，其精确的运动模型通常难以获得。而当水下机器人近水面航行时，复杂的波浪干扰将使其运动状态发生明显的改变，水动力特性也更为复杂，运动的非线性更加显著。在二阶波浪力的抽吸作用下，水下机器人会出现逐渐上浮的现象。因此，水下机器人近水面的定深控制是比较困难的。变结构控制作为控制的综合方法，其优点在于可采用不精确的数学模型进行控制器设计，且其滑动面的设计与控制对象的参数以及各种外干扰变化无关，成为水下机器人近水面控制的有效方案。论文旨在探讨变结构控制技术在水下机器人近水面运动控制中的应用，并设计出性能优良的水下机器人运动控制系统。首先在水下机器人六自由度动力学模型基础上，根据实际需要进行了适当简化，采用波浪频谱的方式对近水面航行时所受到的波浪干扰力进行了数值计算和仿真研究；接着研究了一类可控正则型非线性系统的变结构控制问题。对于可控正则型多输入系统，选择分散滑模控制模式，将可控正则型系统化为线性简约型。采用极点配置法设计了切换函数，应用指数趋近率和光滑函数法来削弱变结构控制系统中的抖振现象，并为了消除波浪干扰下可能出现的稳态误差，在变结构控制器中加入积分项；最后对所设计的水下机器人积分变结构控制器分别进行了静水域和波浪干扰下的仿真试验。系统仿真表明，所设计的控制系统动态品质良好，有较强的抗波浪干扰能力，同时也验证了积分变结构控制方法对于水下机器人近水面运动控制是可行的和有效的。更多还原

【Abstract】 Autonomous Underwater Vehicle (AUV) is a typical system which is characterized by high nonlinearities, couplings and uncertainties. In general, it is difficult to get its precise dynamic model. The motion of AUV changes obviously when it navigates near surface under the influence of ocean waves. The hydrodynamic effect becomes more complicated and the nonlinearity of its motion becomes more notable. The AUV will float up to the surface and finally floats out of the surface under the influence of the second-order wave forces. So it is difficult to sustain the depth.As an integrate control method, the merit of Variable Structure Control (VSC) method lies in that it can use imprecise mathematical models to design the controller. Besides, the design of sliding side is insensitive to uncertainties including parameter variations and external load disturbance. So it is suitable to control the movement of AUV’s navigating near surface.This dissertation aims at the application of VSC to the motion control of AUV’s navigating near surface, and trying to design a control system which performs better. Firstly, dynamic model of AUV with 6 degrees of freedom is properly simplified for the need of practice. Wave forces are calculated numerically through wave spectrum and simulation research is carried out when the AUV navigates near the surface. Then a kind of VSC problem of controllable regular nonlinear system is researched in this dissertation. For the controllable regular multi-input nonlinear system, a decentralized control strategy is selected and the system is changed into the linear reductional form. The pole setting method is used to design the switching function. In order to eliminate chattering, the tendency ration strategy and the slippery function method is used. Besides, an integrator is added to the controller to reduce the steady-state error under the wave disturbances. Finally, simulation experiment is carried out at two situations: in deep ocean without wave disturbances and near surface with wave disturbances. Simulation results show that the controller presented in this dissertation provides high performance dynamic characteristics and anti-jamming ability. Also it is validated that the Integral VSC method is suitable and effective for the motion control of AUV’s navigating near surface.更多还原