A machine analyzer is connected to an active vibration cancellation system in order to identify the operating status of the moving machinery while using a minimum of additional parts and taking advantage of signal processing already occurring in the active vibration cancellation system. A preferred embodiment employs a neural network pattern classifier in connection with detecting operating states such as cylinder misfires in an internal combustion engine.

Integrated active vibration cancellation and machine diagnostic system

An active force cancellation system adapted to contain vibrations in flexible structures which utilizes co-located vibration sensors (5) and counter-vibration devices (4) to offset linear disturbances without setting off sub-structure vibrations.

Active force cancellation system

A method of and a system for active vibration control of an extended mechanical structure having a point or region at which unwanted vibrations are to be reduced or suppressed, wherein a plurality of uni-axial inertial actuators (4, 5) are disposed to act on a rigid intermediate part such as a flange (1) attached to the point or region of the structure. The actuators may be controlled by an electronic controller (35, FIG. 3) to which are fed control signals from accelerometer sensors (27, 28) adjacent the flange (11).

Active vibration control

A device for attenuating the periodic vibrations of a mechanical structure adapted to obtain cancellation of periodic vibrations of rotating machines including at least one transducer, detecting original vibrations, delivering a detected signal, a detector of the periodicity of these vibrations delivering a synchronizing signal, and a control circuit and a transducer generating compensation vibrations which are applied to the mechanical structure. The control circuit includes a circuit for synchronous filtering of the detected signal, controlled by the synchronizing signal and delivering a filtered signal whose frequency spectrum contains only the instaneous fundamental frequency of the detected signal. A circuit for regulating the filtered signal delivers an antivibration-control signal applied to a generating transducer in order to minimize the amplitude of the detected signal.

Device for attenuating the periodic vibrations of a mechanical structure

A method of and apparatus for scale factor compensation for piezo-electric rate sensors maintains the magnitude of vibration at a primary pick-off point substantially constant to enable one of the variables of a vibrating structure--the piezo-electric charge coefficient β to be determined, and thereby enables variation of the scale factor of the sensor from a calibrated value to be determined. This enables correction of the sensor output by a computational scale factor control unit to ensure that the output therefrom allows for a more accurate sensor. Thus, sensors are provided for applications requiring a higher degree of accuracy than they were previously able to provide for.

Scale factor compensation for piezo-electric rate sensors

A dynamic vibration absorber for reducing vibrations of a platform induced by an oscillating mass mounted thereon is provided by mounting a mass of equal mechanical resonant frequency as that of the oscillating mass and oscillating this mass in a manner to establish an equal and opposite vibration of the platform, thereby cancelling the vibrations induced by the oscillating mass. In one embodiment, a signal from the oscillating mass representative of the frequency and amplitude of its mechanical oscillation is phase shifted and utilized as a driving signal to the drive motor of the absorber mass. In another embodiment, electrical signals representative of the platform vibrations are detected to provide phase and amplitude vibration error signals. These error signals are applied to a reference signal coupled to the drive motor of the canceller mass causing the oscillations of the canceller mass to induce vibrations in the platform which counter the vibrations induced by the oscillating mass.

Method and apparatus for countering vibrations of a platform

A dynamic vibration absorber for reducing vibrations of a platform (19) induced by an oscillating mass (17) mounted thereon is provided by mounting a mass (12) of equal mechanical resonant frequency as that of the oscillating mass and oscillating this mass in a manner to establish an equal and opposite vibration of the platform (19), thereby cancelling the vibrations induced by the oscillating mass (17). In one embodiment, a signal from the oscillating mass (12) representative of the frequency and amplitude of its mechanical oscillation is phase shifted and utilised as a driving signal to the drive motor of the absorber mass. In another embodiment, electrical signals representative of the platform vibra­tions are detected to provide phase and amplitude vibra­tion error signals. These error signals are applied to a reference signal coupled to the drive motor of the canceller mass causing the oscillations of the canceller mass to induce vibrations in the platform which counter the vibrations induced by the oscillating mass.

James R. Brazell

Papers

Method and apparatus for countering vibrations of a platform

Method and apparatus for cancelling vibrations