基于隐式增量动态逆的水下运载器出水姿态控制

显式动态逆控制直接利用非线性对消来实现对系统的精确线性化,但由于实际模型存在不确定性因而会造成在对消过程中存在逆误差,使得控制的鲁棒性难以保证。在解决水下运载器出水运动问题中,由于存在较强的不确定性,显式动态逆控制无法消除逆误差的影响。出水过程中水动力变化剧烈同时海浪强烈作用,因此需要对姿态控制问题进行着重研究。在仿射形式的水下运载器出水运动数学模型基础上,推导并得到了隐式增量形式的动态逆控制律,利用层叠结构思想将系统划分为慢快两个回路。在时标分离的慢快回路基础上,引入状态变化率反馈,设计了不依赖精确数学模型的隐式增量控制律,提高了控制的鲁棒性。基于隐式动态逆相应的控制算法,考虑海浪作用、水动力参数摄动以及测量噪声的影响下,对水下运载器出水姿态进行跟踪控制,验证了控制律的有效性和合理性。

Attitude Control of Underwater Vehicle out of Water Based on Implicit Nonlinear Dynamic Inversion

In explicit nonlinear dynamic inversion (NDI) control, a system is linearized accurately using nonlinear offset. However, because of the inversion errors in offset from the uncertainties of real models, the robustness of control system is hard to be guaranteed. Explicit NDI is found facing serious challenges when solving the motion issue of underwater vehicle exceeding water. Considering the severe change in hydrodynamic force and the strong impact of waves, its attitude control has become a research focus. Firstly, the control law of dynamic inversion in the form of implicit increments is derived and obtained, and the system is divided into a slow loop and a fast one using the idea of stepped construction on the base of affine motion model of underwater vehicle out of water. Then the feedback of state variation rate is introduced, the implicit control law independent of accurate models and with better robustness is designed based on these two time-scale separated loops. Finally, based on the implicit NDI control algorithm, the attitude of underwater vehicle in its out-of-water process is traced under the influence of waves and perturbation of hydrodynamic parameters and measurement noise, and the validity and rationality of the control law are verified.