航天器姿态跟踪的非线性离散滑模仿真模型设计

Attitude tracking control model design for rigid spacecrafts based on discrete-time sliding mode

摘要:

为提高三轴稳定刚体航天器对时变参数摄动及外界环境干扰的鲁棒性能,提出一种基于非线性离散滑模控制的姿态跟踪控制系统设计方法．建立了航天器姿控模型,针对该模型中存在的时变特性与干扰力矩,将原系统进行反馈线性化解耦和模型离散化,由离散指数趋近律推导了离散滑模姿态控制律．依据某航天器的模型数据进行的仿真结果表明,所设计的离散滑模姿控系统在确保航天器姿态稳定的同时,实现了各通道的解耦控制,可有效减小干扰引起的姿态角跟踪偏差,对系统外干扰和内部参数摄动都具有良好的鲁棒性能,同时还验证了对指令跟踪的动态性能与采样周期的关系．

Abstract:

In order to improve the robust performance to parametric perturbations and external environment disturbances for rigid spacecrafts, an attitude tracking controller based on the discrete-time sliding mode control principle is proposed. The spacecraft model is firstly modeled. Considering the time-varying and interfering moments and even disturbances, the system is then decoupled into independent discrete-time subsystems via the input-output feedback linearization. To this end, the discrete-time sliding mode attitude control law is designed from the exponential approach law. Simulation results indicate that the discrete-time control system proposed can ensure the attitude stabilization of rigid spacecrafts while realizing the decoupling control among channels. Moreover, the system is robust to the parametric perturbations and external disturbances and the attitude angle tracking errors can be reduced effectively. In addition, the tracking dynamic characteristics and the sampling period are validated for the system considered.