无人机自主着陆的双环混合迭代滑模控制

Double-loop hybrid iterative quasi-sliding mode control strategy for autolanding of UAV

提出了一种无人机自主着陆精确轨迹跟踪的双环混合迭代滑模控制器。外环和内环均采用两级混合迭代滑模控制方法,第一级滑模采用全局动态切换函数,第二级迭代滑模切换函数中引入了非线性积分项,并采用准滑模控制的策略。该方法消除了滑模控制的到达运动阶段,在保持传统积分滑模控制精度的同时,还消除了积分滑模固有的超调和变结构控制的抖振问题。通过在外环滑模切换函数中引入俯仰角的微分项,直接设计俯仰角微分指令,克服了传统方法需要求俯仰角指令微分的缺点。理论推导和仿真结果均表明,该方法具有良好的动态跟踪性能和很强的鲁棒性。

A novel double-loop hybrid iterative quasi-sliding mode control strategy was presented for autolanding of UAV. Both out loop and inner loop use two-rank hybrid iterative quasi-sliding mode control,of which the first rank uses global dynamic sliding-mode switch function and the second rank uses switch function with nonlinear integrator and quasi-sliding mode control strategy. While maintaining the tracking accuracy of the traditional integral sliding mode control,the strategy eliminates the reaching stage of sliding mode controller,avoids overshoot of integral sliding mode control and inherent chattering of sliding mode variable structure controller. And it overcomes the deficiency of conventional double-loop control which has to make differential of pitch angle signal. Both theory and simulation results showed the excellent dynamic tracking and strong robust capability of the proposed strategy.