参数不确定与有界干扰自由飘浮柔性空间机械臂基于速度观测器的奇异摄动鲁棒控制及振动抑制

摘要

讨论载体位置、姿态均不受控情况下系统参数不确定与有界干扰自由漂浮柔性空间机械臂基于速度观测器的奇异摄动鲁棒控制及振动抑制问题。利用拉格朗日方程结合动量守恒原理获得自由飘浮柔性空间机械臂系统动力学方程；用奇异摄动法将柔性空间机械臂系统分解为关于关节轨迹跟踪的慢变子系统与描述柔性杆件振动的快变子系统。以此为基础，提出含慢、快变控制项的复合控制器。将动态滑模观测器与鲁棒控制结合，获得系统慢变控制力矩实现关节轨迹跟踪。对快变子系统基于线性观测器及线性系统最优控制理论获得系统快变控制力矩实现柔性杆振动抑制。并数值仿真证实方法的有效性。该控制方案仅需精确的载体姿态、关节角位置及柔性振动模态坐标反馈，而无需测量载体姿态角速度、关节角速度及角加速度、柔性振动模态坐标导数及漂浮基位置、移动速度、移动加速度。%The robust control based on a velocity observer was introduced for a free-floating flexible space manipulator with unknown payload parameters and bounded disturbances.The dynamic model of the free-floating space manipulator with a flexible link was established by applying the momentum conservation principle and the Lagrange equations.The singular perturbation model of the flexible space manipulator system was obtained according to the two-time scale control theory,in which the system was decoupled into slow (rigid)and fast (flexible)subsystems.Then a composite controller consisting of a slow control component and a fast control component was proposed.A sliding observer based robust control algorithm was applied to control the slow subsystem with unknown payload parameters and bounded disturbances to track the desired trajectory.The fast controller was designed with the estimated velocity based on a linear observer to damp out the vibration of the flexible link using optimal linear quadratic regulator (LQR)method.Finally,a numerical simulation was carried out,which confirms the controller proposed was feasible and effective.The virtue of this control scheme is that the linear position,linear velocity,linear acceleration and angular velocity of the base,the angular velocities,angular accelerations of the joint as well as the derivative of the flexible vibration mode needn't be measured directly.