Linear control design for active vibration isolation of narrow band disturbances

When an engine is mounted on a structurally flexible vehicle, it is important to inhibit the transmission of vibrations of the engine into the structure. In the past, vibration isolation has been achieved using passive schemes. Active control at the mount should permit a marked improvement in its vibration isolation characteristics. Three control schemes for actively controlling engine mounts are presented. The first method uses classical control ideas and physical insights for designing a compensator that provides broadband control. Stability issues are considered and provide motivation for pursuing other control methodologies. The second and third control schemes are variations on linear quadratic Gaussian (LQG) theory with augmented states added to the system matrix. Knowledge of the disturbance spectrum dictates the choice of the augmented states for both of the LQG schemes. The resulting compensators are a sequence of notch filters where the notches occur at the disturbance frequencies