菱形翼布局无人机自适应分数阶滑模姿态控制

Attitude control for diamond joined-wing unmanned aerial vehicle based on adaptive fractional sliding mode control

摘要:

为研究存在复合干扰的非常规布局菱形翼长航时侦察无人机姿态控制问题,针对系统存在强耦合、非线性、多输入多输出等特点,结合滑模变结构控制理论、分数阶微积分理论、自适应控制理论、新型基于非线性fal函数的快速趋近律及扩张状态干扰观测器,提出了一种包含干扰观测器的自适应分数阶微积分滑模控制方法.首先,为降低控制器的超调现象,结合分数阶微积分理论,利用分数阶微积分算子信息记忆和遗忘的特性,设计了分数阶微积分滑模面,以柔化控制器的输出,使得控制器超调现象得到良好的控制. 其次,为改善传统趋近律收敛时间长,抖震严重等弱点,利用fal函数“小误差大增益,大误差小增益”良好的特性,将非线性fal函数引入到趋近律的设计中,提出了一种可以快速收敛的新型趋近律,平滑无抖震地加快了系统收敛速度. 最后,由于建模误差和外部干扰的存在,使用扩张状态干扰观测器观测出等效干扰并在控制器中引入等效的补偿. 数值仿真结果表明,所提控制方法具有很强的鲁棒性,达到了理想的控制效果.

Abstract:

For the attitude control of diamond joined-wing unmanned aerial vehicle (UAV) with unknown external disturbances, the system has the characteristics of strong coupling, non-linearity, multi-input, and multi-output. Combining with sliding mode variable structure control theory, fractional calculus theory, adaptive control theory, new reaching law based on Fal function, and extended state disturbance observer, an adaptive fractional sliding mode control method was proposed. First, by introducing the fractional calculus theory and utilizing the genetic and memory characteristics of fractional calculus operators, the sliding surface of fractional calculus was designed to soften the controller output and control the overshoot of the controller. Then, in order to improve the weaknesses of traditional reaching law such as long convergence time and serious chattering, a new reaching law was proposed based on the Fal function, which could realize fast convergence without chattering. Finally, since there were modeling errors and external disturbances in the control system, the extended state observer was used to estimate and compensate the combined disturbance online. Simulation results show that the proposed control method had strong robustness and achieved ideal control effect.