空间机器人在轨桁架组装操作基于自适应模糊CNF的阻抗控制

IMPEDANCE CONTROL BASE ON ADAPTIVE FUZZY CNF FOR SPACE ROBOT ON-ORBIT TRUSS ASSEMBLY OPERATION

空间桁架作为空间站一类重要基础设施,在空间站建设中起着不可替代的作用。考虑到组装好的空间桁架所占空间以及火箭的运载能力,一般采用将桁架部件发射入太空并在轨道完成组装。为实现空间桁架的组装、维护等太空任务,对空间机器人在轨插、拔孔操作的力/位姿阻抗控制进行了研究。建立了载体姿态受控形式的空间机器人系统动力学模型;通过桁架部件插头的运动学约束,建立了插头在基连坐标系下的运动学关系。基于阻抗控制原理,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,以实现在轨插、拔孔操作过程中输出力的精确控制。提出了一种自适应模糊组合非线性反馈(composite nonlinear feedback,CNF)控制策略,通过模糊控制器拟合系统不确定参数,作为CNF控制器的补偿输入,以降低不确定参数的影响,提高位姿的控制精度。通过Lyapunov原理证明了系统的稳定性;利用仿真分析,验证了控制策略的有效性。

Space truss is a kind of important infrastructure of space station,which plays an irreplaceable role in the construction of space station.Considering the space occupied by the assembled space truss and the carrying capacity of the rocket,it is generally adopted to launch the truss components into space and complete the assembly in orbit.In order to carry out space missions such as assembly and maintenance of space truss,the force posture impedance control of space robot in orbit insertion and extraction operation is studied.Using the kinematic constraints of the replaced plug,the kinematic relationship of the plug in the carrier coordinate system is established.Based on the principle of impedance control,a second-order linear impedance model is established according to the dynamic relationship between the plug posture and its output force,to realize the accurate control of the output force during the insertion and extraction operation.An adaptive fuzzy composite nonlinear feedback(CNF)control strategy is proposed.To reduce the influence of uncertain parameters and improve the control accuracy of posture,the uncertain parameters are fitted by the fuzzy controller as the compensation torque of the CNF controller.The convergence of the system is proved by Lyapunov principle,and the effectiveness of the controllable strategy is verified by simulation analysis.