Structural control and monitoring using adaptive spatio-temporal filtering

An apparatus for decoupling a multiple-degree-of-freedom (MDOF) response of a linear dynamic system into a single-degree-of-freedom (SDOF) modal response, said apparatus comprising:

• at least one sensor, each sensor of said at least one sensor mounted at a location on said linear dynamic system for generating at least one measured response signal representing actual response of said linear dynamic system at said location;
• a data acquisition system for periodically sampling said at least one measured response signal at different instances in time and storing a digitized sample of said at least one measured response signal for each of said different instances in time, said digitized sample representing a MDOF response of said linear dynamic system at one of said different instances in time;
• a digital signal processor including a central processing unit for reading said digitized sample and calculating therefrom a spatio-temporal filter including a set of spatio-temporal filter coefficients;
• and
• a synthesizer for applying said spatio-temporal filter coefficients to said digitized sample from selected instances in time, and for generating a synthesized response signal representing a decoupled SDOF modal response of said linear dynamic system.

An apparatus for calculating a spatio-temporal filter for decoupling a multiple-degree-of-freedom (MDOF) response of a linear dynamic system into a decoupled single-degree-of-freedom (SDOF) modal response, said apparatus comprising:

• a data acquisition system for periodically sampling at least one response signal and at least one input signal at different instances in time, storing a sequence of digitized samples for said at least one response signal and said at least one input signal, and associating each of said digitized samples with one of said different instances in time;
• wherein said at least one response signal represents the dynamic output of said linear dynamic system and said at least one input signal represents an excitation applied to said linear dynamic system;
• a central processing unit for formning a reference model having dynamic characteristics substantially similar to a single mode of said linear dynamic system, and generating a SDOF reference modal coordinate response by reading and applying said at least one input signal to said reference model;
• and
• means for calculating from said sequence of digitized samples a set of spatio-temporal filter coefficients, said set of spatio-temporal filter coefficients being based upon a plurality of said digitized samples and having values which, for each of said different instances in time, when simultaneously applied to a plurality of said digitized samples from selected instances in time will synthesize a signal which substantially matches said SDOF reference modal coordinate response at each of said different instances in time.

An apparatus for generating a synthesized signal corresponding to a decoupled single-degree-of-freedom (SDOF) modal response of a linear dynamic system excited in a manner producing a multiple-degree-of-freedom (MDOF) response, said apparatus comprising:

• a plurality of excitation inputs applied to said linear dynamic system;
• a plurality of input sensors for generating a plurality of input signals representing said plurality of excitation inputs;
• a plurality of response sensors mounted at spaced locations on said linear dynamic system for generating a plurality of measured response signals representing actual (MDOF) responses of said linear dynamic system at said spaced locations;
• a data acquisition system for periodically sampling during a plurality of sampling cycles said plurality of input signals and said plurality of measured response signals for producing digitized samples of said plurality of input signals and said plurality of measured response signals;
• a central processing unit for reading said digitized samples of said plurality of input signals and said plurality of measured response signals, and generating in response thereto a modal filter and a set of input influence coefficients;
• a plurality of subcomponent reference models created by said central processing unit for generating a plurality of subcomponent reference modal coordinate response signals when said plurality of input signals are applied to said plurality of subcomponent reference models;
• and
• wherein said central processing unit includes means for associating each of said input influence coefficients with one of said subcomponent reference models.

A method of generating a plurality of synthesized signals representing decoupled single-degree-of-freedom (SDOF) responses being simultaneously excited in a linear dynamic system, the method comprising the steps of:

• exciting said linear dynamic system;
• generating at least one response signal representing actual response of said linear dynamic system;
• periodically sampling said at least one response signal to produce a sequence of digitized samples thereof, storing said sequence of digitized samples;
• generating a first reference model having dynamic characteristics substantially similar to a first single mode of said linear dynamic system;
• exciting said first reference model substantially similar to said linear dynamic system for producing a first reference model coordinate response at a plurality of instances in time;
• processing said sequence of digitized samples to produce a first set of spatio-temporal filter coefficients, said first set of spatio-temporal filter coefficients being based upon a plurality of said digitized samples associated with said plurality of instances in time;
• and
• applying said spatio-temporal filter coefficients to said at least one response signal for generating said plurality of synthesized signals.

A method of generating a plurality of synthesized signals representing decoupled single-degree-of-freedom (SDOF) responses of a linear dynamic system excited in a manner producing a multiple-degree-of-freedom (MDOF) response, said method comprising the steps of:

• applying a plurality of excitation inputs to said linear dynamic system;
• generating a plurality of input signals representing said plurality of excitation inputs;
• generating a plurality of measured response signals representing actual responses of a plurality of locations on said linear dynamic system;
• periodically sampling said plurality of input signals and said plurality of measured response signals to produce a modal filter and a plurality of input influence coefficients;
• producing a plurality of subcomponent reference models for generating a plurality of subcomponent reference modal coordinate response signals when said plurality of input signals are applied to said plurality of subcomponent reference models;
• and
• associating each of said input influence coefficients with one of said subcomponent reference models having values when applied to said plurality of subcomponent reference modal coordinate response signals, will produce a total SDOF reference modal response corresponding to a decoupled SDOF system response resulting from said modal filter applied to said plurality of measured response signals.