MECHANICAL OSCILLATOR WITH ELECTRONIC FEED-BACK INCLUDING NON-LINEAR CONTROL

摘要

A mechanical oscillator arrangement includes a mechanical structure (30) having at least one transmission path through it, and at least one mode. A controller (40) is provided with an amplifier (70) and a feedback network (80, 90) which together provide a positive feedback oscillator for exciting a mode of the mechanical structure (30). The feedback network (80, 90) comprises a non linear amplitude control element (N-LACE) (90), a frequency dependent gain element with an electronic transfer function, and a phase compensator (80). The mechanical oscillator arrangement also includes an actuator (606) which excites the mechanical structure (30) based upon an output from the controller (40), and a sensor (60a) which senses vibrations in the mechanical structure (30) and then outputs a signal to the controller (40) based upon the sensed vibrations. Such a stabilized positive feedback arrangement is self exciting at the effective resonance frequency of the mechanical structure and avoids the need for an external fixed or variable frequency driver.