航天器交会对接模拟系统逼近过程自抗扰控制

航天器交会对接地面模拟系统用于研究航天器交会对接过程的动力学、导航与控制等方面的相关问题。模拟器通过气浮轴承悬浮在大理石平台上来模拟太空的无摩擦微重力环境。通常情况下要保证大理石平台足够水平,由于实际平台不可能完全水平,模拟器的重力分量会使模拟器产生下滑现象,这种现象对大型地面模拟器设备尤为严重。针对模拟器的逼近过程设计了轨迹规划。为了减小测量信号噪声的影响,采用跟踪微分器(TD)对整个逼近过程中的测量信号进行滤波。针对逼近过程中模拟器存在下滑力等干扰问题设计控制器,通过扩张状态观测器(ESO)实时估计干扰量,进而对干扰量进行补偿。对模拟器冷喷气推力系统制定了推力器分配策略,采用脉冲宽度调制(PWM)技术实现对推力的近似等效。提出的控制方法应用于航天器交会对接地面模拟系统,实验结果表明所提出的控制方法能有效消除下滑力等干扰的影响。

Active disturbance rejection control for spacecraft rendezvous and docking simulation system during proximity operations

Spacecraft rendezvous and docking ground simulation system are used to study the dynamics, navigation and control algorithms of spacecraft on the ground. Spacecraft simulators are floated on the marble platform using planar air bearings to simulate a frictionless and space micro-gravity environment. While the marble platform cannot be absolutely horizontal, the component of simulator gravity will lead to the sliding of the simulator on the platform, which is particularly serious for large-scale simulator. In this paper, a trajectory for proximity operations of spacecraft ground simulator is designed. Signal is filtered by tracking differentiator (TD) in the control process. A controller of the simulator is designed to compensate for the disturbances by extended state observer (ESO). The disturbances are estimated in real time. The thruster allocation strategy of the cold jet thrusters system is also designed and control of thrusters using pulse width modulation (PWM) is presented. The method proposed is applied to the spacecraft rendezvous and docking ground simulation system. Experimental results show that the control method is highly effective in reducing the effects of the sliding force disturbance.