无人直升机作为一种特殊的无人飞行器，有着相当广阔的应用前景。由于无人直升机是一个多变量的非线性控制系统，并且存在诸多不确定性，也是目前研究的难点。在建立无人直升机数学控制模型的基础上，首先设计了一般滑模变结构控制器，并针对一般滑模控制器所产生的抖振现象，设计了基于趋近律的滑模控制器，最后进行了仿真对比实验。实验结果表明，该控制器在总距俯仰角控制方面较其他控制器有更好的跟踪效果，且很好地消除了抖振，从而确保了滑动模态的动态品质。

The unmanned helicopter is a special unmanned aircraft with a broad application prospect.However,the unmanned helicopter itself is a multivariable,nonlinear control system with strong coupling and many uncertainties.In this paper,the mathematical model of unmanned helicopter is presented,and a conventional sliding mode variable structure controller is designed at first.Then,a reaching law based sliding mode controller is designed to depress the chattering of the conventional sliding mode controller.Simulation experiment is carried out finally.The experimental results indicate that the reaching law based sliding mode controller has a better tracking effect than the other controllers on collective pitch angle control,and is effective for chattering attenuation,which can ensure the sliding mode dynamic quality.