含有柔性关节的柔性机械臂同时受到关节柔性、连杆柔性和轴承摩擦的影响，会导致输出角速度发生波动。角速度的波动会加剧机械臂的振动，影响末端执行器的控制精度。本文通过含有干扰观测器的PI控制策略控制角速度波动的方式减弱机械臂的振动。首先使用连续体的振动理论和拉格朗日方法建立考虑轴承摩擦并且含有柔性关节的柔性机械臂的动力学方程。接下来，根据鲁棒稳定性定理设计了干扰观测器中的低通滤波器。然后通过超限补偿控制律的设计满足柔性机械臂控制系统闭环的稳定性。最后开展了含有柔性关节的柔性机械臂的数值仿真分析和控制实验。仿真和实验结果显示：本文所设计的干扰观测器可以有效的降低轴承摩擦力矩的影响，使角速度跟踪误差的标准差降低17.488%。由此，本文所提出的控制策略能够有效的抑制柔性机械臂工作过程中的角速度波动，进而减弱振动。
Abstract
The flexible manipulator with a flexible joint is affected by joint flexibility, link flexibility, and bearing friction, which will cause the output angular velocity to fluctuate. Fluctuations of angular velocity will aggravate the vibration of the manipulator and affect the control accuracy of end-effectors. In this paper, the PI control strategy with a disturbance observer is used to control the angular velocity’s fluctuation to weaken the vibration of the manipulator. Firstly, the dynamic equations of the dual-flexible manipulator servo system considering bearing friction are established based on the theory of the continuum and Lagrangian principle. Next, the low-pass filter in the disturbance observer is designed according to the robust stability theorem. Then, the design of the overrun compensation control law satisfies the stability of the closed-loop of the servo system. Finally, the numerical simulation analysis and control experiments of the manipulator are carried out. Simulation and experimental results show that the disturbance observer designed can effectively reduce the influence of the bearing friction torque and reduce the angular velocity tracking errors’ standard deviation by 17.488%. Therefore, the control strategy proposed in this paper can effectively suppress the angular velocity fluctuations during the working processes of the flexible manipulator with a flexible joint, thereby reducing the vibration.
关键词
柔性机械臂 /
干扰观测器 /
PI控制策略 /
振动抑制
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Key words
flexible manipulator /
disturbance observer /
PI control strategy /
vibration suppression
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