全景式航空相机的离散滑模控制

Discrete-time sliding-mode control in panoramic aerial camera

为了提高全景式航空相机镜筒速度控制系统的动态特性,使其具有响应速度快且超调小的特点,本文提出一种基于降维状态观测器的离散滑模控制方法,对镜筒角速度、角加速度进行观测,并对其速度系统进行控制.针对高氏趋近律带来的控制抖振和稳态抖振问题,本文采用幂次函数趋近律的方法,并对这种方法进行了无抖振理论分析以及稳定性证明.最后以某全景式航空相机作为实验平台,将基于幂次函数趋近律的离散滑模控制应用到镜筒速度控制系统中.实验结果表明,本文提出的控制方法能够有效地减小系统的抖振,使镜筒速度控制系统表现出良好的动态品质.

A discrete-time sliding-mode control method based on reduced-order state observer is proposed to provide fast response and small overshoot for the drawtube control system of a panoramic aerial camera. In this method, the angular velocity and acceleration of the camera are measured for controlling the velocity system, and a power-function reaching law is proposed to substitute the conventional reaching law for suppressing the control chattering and the steady- state chattering caused by the conventional reaching law. The non-chattering characteristics and the system stability are analyzed theoretically. This controller has been applied to control the drawtube system of a panoramic aerial camera on an experimental platform; the experiment results show that this control scheme can effectively eliminate the chattering and make the drawtube system achieve desired dynamical performances.