Active control on the structural vibration under base excitations using a linear oscillatory actuator

Abstract

An active control system using a linear oscillatory actuator (LOA) is studied to suppress structural vibration. A voice-coil-type LOA having the moving mass of 23 kg weight is designed and fabricated for good linearity and high-frequency performance. The LOA consists of permanent magnets, a coil-wrapped nonmagnetic hollow rectangular structure, and an iron core for magnetic flux. When the coil is fed with current, changing its polarity, an oscillating force is produced to the moving mass in the magnetic field. Structural vibration is measured by the accelerometer attached to the structure and the level of vibration is reduced by the optimally controlled motion of the moving mass of the LOA giving anti-phase inertia force to the structure. Among the direct output feedback control methods, the suboptimal control method based on the linear quadratic control is adopted to modify the original control gain. Numerical simulations and experimental tests to verify its performance are carried out on the test structure of about 500 kg subjected to sinusoidal or random base excitation. From these tests, it is confirmed that the acceleration level of the structure is drastically reduced near the resonant region.