Abstract: Aiming at uncertainties and external disturbances in fixed-wing UCAV systems, an adaptive super twisting sliding mode controller based on extended state observer is designed to suppress system’s disturbances in this paper, thus the control performance of UCAV has bean improved. A six-degree-of-freedom nonlinear model of fixed-wing UCAV is established, then the extended state observer for attitude control and velocity control is designed respectively to estimate states and external disturbances which are difficult to measure accurately in the model. According to the principle of singular perturbation, an adaptive super twisting sliding mode controller is designed for attitude and velocity respectively to achieve tracking control of UCAV’s attitude and velocity. To verify the controller designed in this paper, a certain type of nonlinear model of fixed-wing UCAV is used to simulate and compared with the traditional active disturbance rejection control based on sliding mode control method. The simulation results show that the adaptive super twisting sliding mode controller based on extended state observer designed in this paper has smaller overshoot and steady state error.

Key words: fixed-wing Unmanned Combat Aerial Vehicle（UCAV）, flight control, extended state observer, super twisting algorithm, second-order sliding mode control

摘要： 针对固定翼UCAV（Unmanned Combat Aerial Vehicle）系统中存在的不确定性和外部扰动，设计了一种基于扩张状态观测器的自适应超扭曲滑模控制器用来抑制系统扰动，从而提高对于UCAV的控制性能。建立固定翼UCAV的六自由度非线性模型，针对姿态控制和速度控制分别设计扩张状态观测器对模型中难以精确测量的状态量和外部扰动进行估计，依据奇异摄动原理分别对姿态和速度设计自适应超扭曲滑模控制器，实现对UCAV的姿态和速度的跟踪控制。采用某型固定翼UCAV非线性模型对所设计的控制器进行仿真验证，并且与传统的自抗扰滑模控制方法进行了对比，仿真结果表明，基于扩张状态观测器的自适应超扭曲滑模控制器具有更小的超调量和稳态误差。

关键词: 固定翼UCAV, 飞行控制, 扩张状态观测器, 超扭曲, 二阶滑模控制