A comparison of semi-active damping control strategies for vibration isolation of harmonic disturbances

Active vibration isolation systems are less commonly used than passive systems due to their associated cost and power requirements. In principle, semi-active isolation systems can deliver the versatility, adaptability and higher performance of fully active systems for a fraction of the power consumption. Various semi-active control algorithms have been suggested in the past, many of which are of the “on–off” variety. This paper studies the vibration isolation characteristics of four established semi-active damping control strategies, which are based on skyhook control and balance control. A semi-active damper is incorporated into a single-degree-of-freedom (s.d.o.f.) system model subject to base excitation. Its performance is evaluated in terms of the root-mean-square (r.m.s.) acceleration transmissibility, and is compared with those of a passive damper and an ideal skyhook damper. The results show that the semi-active system always provides better isolation at higher frequencies than a conventional passively damped system.