Active vibration isolation system employing electro-rheological fluid

Claim 2

A viscous damper for reducing the transmission of mechanical excitations between a payload and a base, said damper comprising: an actuator; an accumulator; means for fluidically coupling said actuator to said accumulator, said coupling means having therein electro-rheological fluid and including first and second conductive elements, an insulative element interposed between said first and second conductive elements, and means for directing fluid flow through said coupling means in a first and a second direction from said first conductive element to said second conductive element; and means for applying a voltage differential to said first and second conductive elements.

Claim 3

An active vibration isolation system comprising first means for deriving a first control signal, a viscous damper having a variable damping coefficient, means for modulating the damping coefficient of said viscous damper in response to a command signal, and electronic control means for continuously generating the command signal in response to said first signal, whereby the damping coefficient is controllable.

Claim 4

An active vibration isolation system comprising first means for deriving a first control signal, a viscous damper having a variable damping coefficient, means for modulating the damping coefficient of said viscous damper in response to a command signal, and electronic control means for continuously generating the command signal in response to said first signal, whereby the damping coefficient is controllable.

Claim 5

The active vibration isolation system of claim 2 wherein the first signal is representative of the velocity of relative movement between a payload and a base, said payload being interconnected with said base by said viscous damper.

Claim 6

The active vibration isolation system of claim 3 wherein said first deriving means includes a first sensor operatively coupled to said payload and a second sensor operatively coupled to said base.

Claim 7

The active vibration isolation system of claim 3 wherein said first deriving means includes first and second sensors, each including a geophone, for detecting velocity of said payload and base, respectively.

Claim 8

The active vibration isolation system of claim 3 wherein said modulation means includes a servovalve having therein electro-rheological fluid.

Claim 9

The active vibration isolation system of claim 6 wherein said viscous damper includes first and second chambers, and said servovalve includes means for fluidicly coupling said chambers including means for directing fluid flow therethrough, and said system further comprises means for applying an electric field across said fluidic coupling means.

Claim 10

The active vibration isolation system of claim 7 wherein said fluidic coupling means includes first and second spaced conductive elements and a third insulative element disposed therebetween, said conductive and insulative elements fluidically connected by said flow directing means.

Claim 11

The active vibration isolation system of claim 2 wherein said first means includes a first sensor for deriving a first velocity signal, E X , representative of the velocity of a payload, and a second sensor for deriving a second velocity signal, E u , representative of the velocity of a base.

Claim 12

The active vibration isolation system of claim 9 wherein said electronic control means includes: (a) coupler means receiving signal E X from said first sensor and outputting a signal E n ; (b) means for subtracting one of said signals E X and E U from the other so as to derive a signal E d representative of the velocity of relative motion of the payload and base; (c) means for dividing signal E x by signal E d and deriving an output signal, E R ; (d) means for amplifying said signal, E R ; and (e) controller means responsive to said signals E R and E d , for deriving said command signal and applying said command signal to said modulating means.

Claim 13

The active vibration isolation system of claim 8 characterized by an equation of motion which is substantially in accordance with: M(d² X ) = K(U - X) - C[ABS(dX)]DELTA

Claim 14

The active vibration isolation system of claim 8 wherein said viscous damper further comprises an actuator, having said first chamber, an accumulator having said second chamber, and said servovalve being in fluidic communication between said actuator and said accummulator.

Claim 15

The active vibration isolation system of claim 12 wherein said actuator includes a support element and an elastomeric wall connecting said support element to said first conductive elements said support element, wall and first conductive element defining said first chamber having therein electro-rheological fluid, and said command signal regulates flow between said actuator and said accummulator by varying the viscousity of said fluid as it flows through said servovalve, thereby modulating the damping coefficient.

Claim 16

The active vibration isolation system of claim 8 wherein said fluid directing means includes a plurality of orifices through said conductive elements to direct fluid flow in a first direction, and channel means for directing fluid flow in a second direction along at least one of said conductive elements.

Claim 17

The active vibration isolation system of claim 14 wherein said channel means includes a plurality of elongate slots defined by and between said insulative element and at least one of said conductive elements, such elongate slot being aligned at one end in said first direction with one of the orifices of said first conductive element; and at another end in said first direction, with one of the orifices of said second conductive element, and wherein fluid flows through said orifices of said conductive elements in said first direction and within said elongate slot in the second direction.

Claim 18

The active vibration isolation system of claim 15 wherein said conductive and insulate elements are plates stacked one atop another in a direction substantially parallel to said first direction.

Claim 19

The active vibration isolation system of claim 12 wherein said accumulator includes: (a) an accumulating cylinder; (b) a diaphragm fluidly separating said accummulator cylinder into said second chamber a third chamber, said second chamber being in fluidic communication with said servovalve, and said third chamber having therein a compressible fluid.

Claim 20

The active vibration isolation system of claim 8 wherein said damping coefficient is controlled by said command signal substantially in accordance with: Damping Coefficient=C=C₀[1.0 + A(ABS(dX/dV)]

Claim 21

An active vibration isolation system comprising: (a) a first geophone operatively associated with a payload for generating a first velocity signal representative of the velocity of the payload; (b) a second geophone operatively associated with a base for generating a second velocity signal representative of the velocity of the base; (c) a viscous damper having a variable damping coefficient fo supporting the payload with reference to the base, said viscous damper including (i) an actuator, and (ii) an accummulator; (d) means for modulating the damping coefficient of said viscous damper a servovalve comprising coupling means including means for directing the flow of an electro-rheological fluid between, and fluidicly coupling said actuator to said accummulator; and (e) circuit means for deriving a command signal dependent upon said first and second velocity signals, for generating an electric field corresponding to said command signal and applying said field across said orifice means.

Claim 22

An active vibration isolation system comprising: (a) a first geophone operatively associated with a payload for generating a first velocity signal representative of the velocity of the payload; (b) a second geophone operatively associated with a base for generating a second velocity signal representative of the velocity of the base; (c) a viscous damper having a variable damping coefficient fo supporting the payload with reference to the base, said viscous damper including (i) an actuator, and (ii) an accummulator; (d) means for modulating the damping coefficient of said viscous damper a servovalve comprising coupling means including means for directing the flow of an electro-rheological fluid between, and fluidicly coupling said actuator to said accummulator; and (e) circuit means for deriving a command signal dependent upon said first and second velocity signals, for generating an electric field corresponding to said command signal and applying said field across said orifice means.

Claim 23

The active vibration isolation system of claim 19 wherein the coupling means includes a first and a second conductive plates, and an insulative plate disposed therebetween, said flow directing means includes means for directing the fluid between said conductive plates in a first and second direction, and said command signal regulates a voltage differential between said conductive plates so as to regulate the viscosity of said electro-rheological fluid and thereby modify the damping coefficient.

Claim 26

The method of claim 21 wherein the step of deriving the first signal includes the steps of: (a) sensing the velocity of said first element and generating a signal representative of said velocity; (b) sensing the velocity of said second element and generating a signal representative of said velocity; and (c) subtracting said generated signals, thereby deriving the first signal.

Claim 27

The method of claim 21 wherein the modulating step includes the step of directing the flow of an electro-rheological fluid through an orificed element and applying an electrical field across said orificed element in response to said commande signal.

Claim 28

The method of claim 23 wherein said flow directing step comprises the steps of directing the flow in a first direction and in a second direction between conductive plates of said orificed element.