柔性空间机器人快速终端滑模容错抑振控制

Fast terminal sliding mode fault-tolerant vibration-suppression control for the flexible space robot

针对基座与臂杆存在柔性且执行机构发生故障的自由漂浮空间机器人系统,设计了快速终端滑模容错抑振控制器。结合线性弹簧假设、欧拉-伯努利梁理论和假设模态法提取了系统的柔性特征,利用拉格朗日方程推导出柔性基、柔性臂空间机器人系统的动力学模型;基于双幂次非奇异快速终端滑模为系统设计了有限时间容错控制器,采用Lyapunov函数法证明了闭环系统的稳定性;在此基础上,引入混合轨迹对容错控制器进行修正,进而构造出基于虚拟控制力的有限时间容错抑振控制器,实现对空间机器人载体姿态与关节轨迹的快速跟踪控制及基座与臂杆柔性振动的有效抑制。仿真结果表明,相较于无容错机制的计算力矩抑振控制算法,所设计算法的轨迹跟踪误差收敛速度提升了68.75%,弹性基座的振幅减小了78%,限定在1.1×10^(-4)m之内。

The fast terminal sliding mode fault-tolerant vibration suppression controller of the flexible-base flexible-link space robot subjected to the actuator fault is designed.Combing the linear spring theory,Euler-Bernoulli beam theory with the assumed mode method,the dynamical model of the flexible-base flexible-link space robot is established by using the second Lagrange equation.A finite-time fault-tolerant controller is proposed for the system based on the dual-power non-singular fast terminal sliding mode,and the stability of the closed-loop tracking system is proven through Lyapunov function method.Then the hybrid trajectory is introduced to amend the finite-time fault-tolerant controller,and a dual-power non-singular fast terminal sliding mode finite-time fault-tolerant vibration-suppression controller on the base of the virtual control force is designed,which can achieve the fast convergences of the tracking errors of the base attitude and the manipulator joints and suppress the elastic vibrations of the flexible base and the flexible link.The simulation results show that compared with the calculated-torque vibration-suppression control algorithm which is lack of the fault-tolerant mechanism,the error convergence rate of the proposed algorithm has increased by 68.75%and the amplitude of the elastic base is reduced by 78%,which can be limited to 1.1×10^(-4)m.