Vibration/noise control system

A vibration/noise control system for controlling vibrations and noises generated with a periodicity or a quasi-periodicity from a vibration/noise source having at least one rotating member, comprising:

• timing pulse signal-detecting means for detecting at least one timing pulse signal exhibiting a period of vibrations and noises peculiar to at least one component part of said vibration/noise source;
• control signal-generating means for generating a control signal for controlling said vibration/noise source;
• electromechanical transducer arranged in at least one of a plurality of vibration/noise transmission paths through which said vibrations and noises from said vibration/noise source transmit;
• driving signal-generating means for generating a driving signal for driving said electromechanical transducer;
• error signal-detecting means for detecting an error signal exhibiting a difference between said driving signal and said vibrations and noises from said vibration/noise source;
• reference signal-generating means for storing a transfer characteristic of a portion of said at least one vibration/noise transmission path extending between said control signal-generating means and said error signal-detecting means, and for generating a reference signal based on said transfer characteristic and said timing pulse signal;
• control signal-updating means for updating said control signal such that said error signal is minimized, based on said error signal, said reference signal and said control signal;
• reference sine wave-generating means for generating a reference sine wave superposed on said control signal for driving said electromechanical transducer;
• delayed sine wave-generating means for generating a delayed sine wave which is delayed by a predetermined delay period M relative to said reference sine wave;
• transfer characteristic-identifying means for identifying said transfer characteristic of said portion of said at least one vibration/noise transmission path, based on said reference sine wave, said delayed sine wave, and said error signal, and for outputting a first identification signal indicative of completion of identification of said transfer characteristic;
• and
• transfer characteristic-updating means for updating said transfer characteristic stored in said reference signal-generating means, based on said first identification signal output from said transfer characteristic-identifying means;
• wherein said transfer characteristic-identifying means is formed of an adaptive digital filter having two taps;
• said predetermined delay period M is set relative to a repetition period of said reference sine wave in a range of 1/3.gtoreq.M.gtoreq.1/7, wherein M is a real number.