Robust vibration control of a flexible manipulator in presence of payload uncertainty

This paper presents the results of hybrid vibration controllers applied for vibration suppression of flexible manipulator. The model of the manipulator is assumed to be uncertain due to varying payload. To cater for the model uncertainty the proposed hybrid controller combines robust input shaping for command input with #x03BC;-controller applied for active vibration suppression using smart materials. Dependence of hybrid controller performance on design frequencies of input shaper is also studied. Results showed that the performance of hybrid controller is strongly dependent on the parameters used for designing input shaper, and the effectiveness of the hybrid controller can be substantially increased by judiciously selecting the design frequencies of input shaper. Effectiveness of the proposed controller is demonstrated by comparative studies with hybrid controllers formed by robust input shaping and PPF (positive position feedback) controller. Results are compared for suppressing vibrations resulting from slewing motion of manipulator, where the slewing motion is controlled by the PD controller. Results of comparisons showed that the μ-controller gave better performance in terms of settling time and energy consumption than those using PPF.