漂浮基闭链双臂空间机器人抓持系统动力学及载荷力/位置混合控制的模糊变结构控制器设计

讨论了载体位置、姿态均不受控制的漂浮基双臂空间机器人抓物系统的动力学建模和控制问题. 利用拉格朗日方法和牛顿欧拉法分别建立了双臂空间机器人及负载的非线性动力学模型, 结合空间机器人固有的特性及闭合链约束关系, 得到抓持系统合成动力学方程. 以此为基础, 考虑到空间机器人系统结构的复杂性及某些参数的变动性, 根据具有较强鲁棒性的变结构控制理论, 针对该抓持系统惯性空间轨迹跟踪设计了全局滑模控制方案及相应的PI内力控制方案, 从而达到位置、力的混合控制. 为克服滑模控制器抖振的缺点, 附加设计了模糊控制器, 根据系统的输出来动态调节滑模控制器的参数, 从而既可确保系统的快速响应又可降底原有的抖振. 系统数值仿真证明了上述控制方案的有效性与准确性. 

Design for Fuzzy Variable Structure Controller of Hybrid Position and Force Control for Dual-arm Coordinated Space Robot Systems

A kind of nonlinear dynamics model of free-floating dual-arm space robot system is based on Lagrange method, and the dynamics model of object is presented based on Newton-Euler method. Based on the results and closed kinematic chain constraints, the dynamics model of synthetical system is obtained, and the control problems for object to track the desired trajectory in workspace and adjustment of interactive forces due to the interaction between the object and the end-effectors are discussed. Because of the high complexity of structure and the uncertainty of parameter of such systems, the scheme of variable structure global sliding-mode control with better robustness to uncertainty and disturbance is proposed to track the desired trajectory of object, and the corresponded scheme of internal forces control is proposed synchronously. Therefore, the object position and internal forces can be regulated simultaneously. A fuzzy controller is designed to reduce shiver due to the inherent defect of sliding-mode control and ensure rapid response. The fuzzy controller can tune the sliding-mode control law parameters automatically according to the relationship between the system state and switch surface. The effect of the controllers is testified by computer simulation.