Active vibration control system

An active vibration control system comprising:

• at least one vibration source;
• at least one first sensor means for sensing vibration from said vibration source;
• control means disposed to receive an output from said first sensor means as a reference signal, said control means being responsive to said reference signal for generating a cancelling signal having a transfer characteristic inverse to a transfer characteristic of vibration from said vibration source to a human body;
• cancelling vibration-generating means responsive to an output from said control means for generating cancelling vibration;
• and
• second sensor means for sensing an error between said vibration from said vibration source and said cancelling vibration from said cancelling vibration-generating means and for generating an error signal indicative of the sensed error,
• wherein said control means varies said inverse transfer characteristic of said cancelling signal by an amount corresponding to a value of said error signal so as to minimize said error;
• said control means comprising divided processing means including oversampling means for oversampling outputs from said first and second sensor means, filter means for dividing the oversampled outputs from said first and second sensor means into vibration components falling respectively within a plurality of frequency ranges including at least a high frequency range and a low frequency range, downsampling means for downsampling said vibration components falling within said low frequency range, and processing means for separately processing said vibration components falling within said high frequency range from said filter means and the downsampled vibration components falling within said low frequency range by FIR type adaptive digital filters.