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Passive, tuned acoustic absorbers, such as Helmholtz resonators (HR) and quarter-wave tubes, are commonly used solutions for abating the low-frequency tonal noise in air induction systems. Since absorption at multiple frequencies is required, multiple absorbers tuned to different frequencies are commonly used. Typically, the large size and multiple numbers of these devices under the hood is a packaging challenge. Also, the lack of acoustic damping narrows their effective bandwidth and creates undesirable side lobes. Active noise control could address all of the above-mentioned issues. Most active noise control systems use feedforward adaptive algorithms as their controllers. These complex algorithms need fast, powerful digital signal processors to run. To ensure the convergence of the adaptation algorithm, the rate of adaptation should be made slow.

We propose the use of an active element in conjunction with a passive, reasonably-damped Suspension to make an engine mount capable of satisfyingBoth damping and isolation requirements while avoiding 1) the loss of performance due to detuning of tunable (such as hydraulic) engine mounts and 2) the undesirable on/off switching associated with the decoupler in hydraulic mounts. In the proposed scheme, the damping will be provided by the proper choice of damped elastomeric material and isolation will be achieved by controlling the active element using a novel kalman-estimator based algorithm developed by the authors. To demonstrate the effectiveness of the proposed mounting scheme the distributed parameter models of a typical engine/chassis system was developed. Finite element analysis of the chassis was performed to find its natural frequencies and mode shapes which in turn were used to construct the state space control model.