초록 ▼

Primary vibrations (N), e.g. acoustic noise or vibration from a source thereof such as a motor, are cancelled by secondary vibrations (C) produced by an actuator (2) driven by a controller (3) that is responsive to an error signal (E) detected by a detector (4) and representative of the residual or

Primary vibrations (N), e.g. acoustic noise or vibration from a source thereof such as a motor, are cancelled by secondary vibrations (C) produced by an actuator (2) driven by a controller (3) that is responsive to an error signal (E) detected by a detector (4) and representative of the residual or difference between the primary and secondary vibrations. The controller samples the error signal (E) during successive sampling periods determined by a synchronising signal (syn) taken from the motor. The secondary vibrations Cn+1 for a sampling period n+1 are determined as follows: Cn+1=Cn-mnSGN[1/], where Cn represents the secondary vibrations produced during a preceding sampling period (n); En represents the detected error signal for said preceding period n, H represents the transfer coefficient between the actuator (2) and the detector (4) and mm

대표청구항 ▼

A method of cancelling primary vibrations using secondary vibrations produced by a secondary source, comprising the steps of: utilizing detecting means to detect respective indicia of said primary and said secondary vibrations; producing an error signal as a function of the difference between said p

A method of cancelling primary vibrations using secondary vibrations produced by a secondary source, comprising the steps of: utilizing detecting means to detect respective indicia of said primary and said secondary vibrations; producing an error signal as a function of the difference between said primary and said secondary vibrations; sampling said error signal during successive sampling periods; and producing said secondary vibrations for a particular sampling period in dependence upon: (a) predetermined indicia of said secondary vibrations produced for a preceding sampling period; and (b) a term which is a function of the vector product of: (i) a vector signal which is a function of the error signal for a preceding period; and (ii) only the sign of a vector signal which is a function of the transfer coefficient between said secondary source and said detecting means.