面向在轨组装服务的空间机器人动力学分析及抑振阻抗控制设计

Dynamic Analysis and Vibration Suppression Impedance Control of Space Robot for On⁃Orbit Assembly Service

研究了空间机器人在轨组装空间桁架操作的抑振阻抗控制问题.首先,利用Lagrange方法建立了载体姿态受控形式的空间机器人系统动力学模型;通过对系统进行动力学分析,推导了相应的机械臂末端和桁架插头在基连坐标系下的运动雅可比关系;结合阻抗控制原理,根据插头位姿与其输出力之间的动态关系建立了二阶线性阻抗模型.然后,设计了标称PD(Proportional Derivative)的控制器,并引入滑模变结构控制器来实现对建模不确定项的精确补偿,以提高力/位的控制精度.考虑滑模控制器固有的抖振,结合模糊控制原理,采用将滑模面作为输入,补偿控制增益作为输出的控制方案来提高抑振效果.该控制策略不依赖滑模面微分信号,计算量少,鲁棒性强,且无需复杂的模糊专家规则库.通过Lyapunov原理证明系统是一致渐进稳定的.基于Matlab仿真结果分析,验证了所提控制策略的有效性和抑振性能.

The vibration suppression impedance control problem of space truss of space robot assembly in orbit is studied.Firstly,a system dynamics model of a single-arm space robot is established using Lagrange's method in terms of carrier attitude control.Through dynamic analysis,the Jacobian relation between the manipulator end-effector and the truss plug within the base coordinate system is derived.Based on impedance control principles,a second-order linear impedance model is established by considering the dynamic relationship between plug pose and output force.Next,a nominal PD(Proportional Derivative)controller is designed and a sliding-mode variable-structure controller is introduced to accurately compensate for the modeling uncertainties,thereby improving the force/position control accuracy.Taking into account of the inherent buffeting associated with the slidingmode controllers as well as the fuzzy control principles,a control scheme utilizing the sliding mode surface as input and the compensation control gain as output is adopted to achieve the vibration suppression effects.This control strategy does not rely on differential signals from sliding-mode surfaces.Also,it requires less computation cost while maintaining strong robustness without complex fuzzy expert rule database.In addition,it has been proven through Lyapunov principle that this system exhibits uniform asymptotic stability.Finally,the effectiveness and suppression performance of the proposed control strategy are verified based on the analysis results of Matlab simulations.