Method and apparatus for actively adjusting and controlling a resonant mass-spring system

The method of controlling an active resonant inertial force generator having a movable mass coupled through at least one spring to a structure, comprising the steps of:

• mounting an externally-powered servoactuator on one of said mass and structure so as to be capable of modulating the vibratory reaction force transmitted between said mass and structure;
• commanding a desired vibratory force, at a desired frequency, to be exerted on said structure by said generator;
• modulating said servoactuator so as to excite the mass-spring system and to continuously adjust the natural frequency of the mass-spring system so as to generate a vibratory reaction force acting on said structure at said commanded frequency;
• measuring said vibratory reaction force;
• and
• controlling the modulation of said servoactuator to minimize the difference between said commanded force and said measured vibratory reaction force.

In an actively-controlled mass-spring system having a resonantly-vibrating mass adapted to exert a vibratory reaction force on a vibrating structure at a mounting point in response to an electrical command signal, the improvement which comprises:

• an externally-powered servoactuator operatively arranged to act on one of said mass and structure;
• means for providing an electrical command signal reflecting a desired force;
• and
• control means responsive to said command signal for modulating said servoactuator so as to cause the resonant frequency of said system to continuously approximate the frequency of said command signal and to resonantly excite the mass-spring system such that the reaction force exerted on said structure is substantially equal to the electrically-commanded force.

A vibratory inertial force generator including an actively-controlled mass-spring system arranged to be resonantly excited so as to exert a vibratory reaction force on a structure, said system having a mass mounted for movement relative to said structure and having a spring arranged between said mass and structure, wherein the improvement comprises:

• an externally-powered servoactuator mounted on one of said mass and structure and arranged to modulate said vibratory reaction force transmitted from said mass to said structure as a function of the acceleration of said mass so as to controllably modify the resonant frequency of said system;
• command means for generating an oscillatory force command signal;
• transducer means arranged to generate a feedback signal proportional to the force transmitted from said mass to said structure;
• and
• means for producing an error signal proportional to the difference between said command signal and said feedback signal.

A vibratory inertial force generator including an actively-controlled mass-spring system arranged to be resonantly excited so as to exert a vibratory reaction force on a structure, said system having a mass mounted for movement relative to said structure and having a spring arranged between said mass and structure, wherein the improvement comprises:

• an externally-powered servoactuator mounted on one of said mass and structure and arranged to modulate said vibratory reaction force transmitted from said mass to said structure as a function of the acceleration of said mass so as to controllably modify the resonant frequency of said system;
• command means for generating an oscillatory force command signal;
• transducer means arranged to generate a feedback signal proportional to the acceleration of said mass;
• means for producing an error signal proportional to the difference between said command signal and said feedback signal;
• and
• control means for modulating said servoactuator as a function of said error signal to cause said system resonant frequency to equal that of the oscillatory force command signal, and to further excite the mass-spring system at its modified resonant frequency so that the reaction force exerted on said structure will be essentially equal to the commanded oscillory force.