Active vibration control system

Abstract

An adaptive control circuit is responsive to a reference signal, i.e. an output from a sensor which senses vibration from a vibration source, for generating a cancelling signal having a transfer characteristic inverse to a transfer characteristic of vibration from the vibration source to a human body. A loud speaker is responsive to an output from the adaptive control circuit for generating cancelling vibration. A microphone senses an error between the vibration from the vibration source and the cancelling vibration from the loud speaker and generates an error signal indicative of the sensed error. The adaptive control circuit varies the inverse transfer characteristic by an amount corresponding to the error signal so as to minimize the above error. A divided processing circuit divides the output from the sensor into vibration components falling respectively within a plurality of frequency ranges and separately processes the divided vibration components. The divided processing circuit has a sampling circuit which samples the divided vibration components at different sampling periods between the above frequency ranges.