Vibration control of flexible structures

Flexible structures exist in systems such as robots, and many aircraft systems. Dynamics of these structures are generally characterized by having low-frequency lightly-damped modes. Disturbances or external forces may excite these modes and affect the system's performance. To solve this problem, the use of piezoelectric materials coupled to structural members, to form smart structural members, is generally applied for active control of these flexible structures. This work focuses on the development of an advanced controller that actively suppresses vibration on a flexible beam. A single-link manipulator including all associated electromechanical items was designed and constructed for this study. A multivariable model-based predictive (MPC) controller was developed and used for this study. Simulation and experimental results demonstrated that the predictive controller effectively increases the system's overall damping. In the simulations of the fast response mode of the flexible beam, the average damping ratios xi in the cases of no vibration control and vibration control using both motor and actuator were 1.55% and 3.73% respectively. Similar results were obtained in slow response mode of the beam. Experiments conducted on fast motion of the beam in the cases of no vibration control and vibration control using both motor and actuator resulted in average damping ratios xi 1.83% and 3.52% respectively. Similar results were obtained in the slow motion case. The predictive controller was also tested on several joint angle setpoints and resulted in good vibration suppression in all cases. Overall, the MPC controller performed well and actively suppressed the beam's vibration.