DESIGN OF A NONLINEAR ROBUST ABSORBER FOR VIBRATION ATTENUATION ON A MECHANICAL SYSTEM-

摘要

This work considers the design of a nonlinear robust absorber for the attenuation or suppression of harmonic vibrations affecting a nonlinear oscillatory mechanical system. The undesirable vibrations on the primary system belong to a range of operating frequencies including resonance frequencies. The approach to solve the problem is based on the design of a nonlinear controller via partial feedback linearization and the use of passive and active vibration control methods. The mechanical system consists of an oscillating rigid bar coupled to a passive absorber, which is able to attenuate harmonic vibrations only for a nominal excitation frequency. For variable excitation frequency we propose to add an extra degree of freedom to the original system, providing a position control of the passive absorber along the rigid bar, in order to apply feedforward and feedback control laws. This modification leads to an underactuated and nonlinear control system. The active vibration control method needs the measurement of the excitation frequency to compute an optimal attenuation position, which is asymptotically achieved by the application of a nonlinear controller. Some numerical simulations are included to illustrate the resulting dynamic behavior and performance using active vibration control.