Reactionless robust finite-time control for manipulation of passive objects by free-floating space robots

On-orbit servicing requires efficient techniques for manipulating passive objects. The paper aims at developing a reactionless control method that drives the manipulator to manipulate passive objects with high precision, while inducing no disturbances to its base attitude. To this end, decomposition of the target dynamics from the base dynamics is discussed, so that they can be considered as two independent subsystems. A reactionless nonlinear controller is presented, which ensures high-precision manipulation of the targets and that the base orientation is unchanged. This is achieved by combining the robust finite-time control with the reaction null space. Finally, the performance of the proposed method is examined by comparing it with that of a reactionless PD controller and a pure finite-time controller.     

轴向冲击下圆柱壳非轴对称屈曲耗散能分析

主要研究受轴向冲击圆柱壳非对称屈曲耗能,从轴向屈曲变形、环向屈曲变形和轴向压 缩变形3个角度进行理论推导. 结果表明: 环向屈曲变形能随屈曲折叠边数增加有减小 趋势, 且占总耗能比例很小,可知圆柱壳受轴向冲击屈曲过程中外力做功主要转变为轴向变形 能,环向屈曲变形消耗外力功很少.     

受重力梯度扰动的空间机器人姿态动力学非线性特征分析

研究考虑重力梯度扰动的自由漂浮空间机器人姿态动力学建模方法.以二连杆空间机器人模型为基础,对机械臂构型固定时系统俯仰姿态受扰运动的非线性特征进行了深入分析.利用相平面轨迹和Poincaré截面对受扰运动特征进行了描述,反映出受扰运动对轨道偏心率的变化比较敏感,在圆轨道时仅有周期摆动和翻滚两种形式,而在椭圆轨道时出现了准周期运动.进一步利用系统分岔图、功率谱图对这种非线性运动特征进行了定量分析.