Fluidic stabilization control

Claim 2

In a fluidic control system generating a fluidic rate signal indicative of rate of movement of a body in a preselected direction, wherein said body has a characteristic natural bending frequency as said body moves in said direction; a fluidic notch filter for reducing said fluidic rate signal to a minimum value at said natural frequency, comprising: sensor means operably coupled with said body for generating a fluidic acceleration signal indicative of acceleration of said body in said direction, said sensor means having a mass with a natural frequency approximately equal to said body natural frequency, the magnitude of said fluidic acceleration signal being approximately equal to the magnitude of said rate signal at said natural frequency but substantially less at other frequencies; and fluidic circuit means for combining said rate signal and acceleration signal to reduce said rate signal to said minimum value at said natural frequency.

Claim 3

In a fluidic control system for controlling movement of a body in a preselected direction, wherein said body has a characteristic natural bending frequency as said body moves in said direction: means for providing an input signal indicative of a desired rate of movement of said body in said direction; a first sensor operably coupled with said body for generating a first fluidic signal indicative of the actual rate of movement of the body in said direction; a second sensor operably coupled with said body for generating a second fluidic signal indicative of acceleration of said body in said direction, said second sensor including a mass having a natural frequency approximately equal to said natural frequency of the body, the magnitude of said second fluidic signal being approximately equal to the magnitude of said first fluidic signal at said natural frequency, and being substantially less than that of said first fluidic signal at other frequencies; fluidic circuit means for summing said first and second fluidic signals to produce a third fluidic signal having essentially zero magnitude at said natural frequency, and a magnitude proportional to said first fluidic signal at said other frequencies; means for comparing said input signal and said third fluidic signal to generate a fluidic error signal; and actuator means responsive to said fluidic error signal and operably associated with said body for adjusting said rate of movement of the body in relation to said error signal.

Claim 4

In a fluidic control system for controlling movement of a body in a preselected direction, wherein said body has a characteristic natural bending frequency as said body moves in said direction: means for providing an input signal indicative of a desired rate of movement of said body in said direction; a first sensor operably coupled with said body for generating a first fluidic signal indicative of the actual rate of movement of the body in said direction; a second sensor operably coupled with said body for generating a second fluidic signal indicative of acceleration of said body in said direction, said second sensor including a mass having a natural frequency approximately equal to said natural frequency of the body, the magnitude of said second fluidic signal being approximately equal to the magnitude of said first fluidic signal at said natural frequency, and being substantially less than that of said first fluidic signal at other frequencies; fluidic circuit means for summing said first and second fluidic signals to produce a third fluidic signal having essentially zero magnitude at said natural frequency, and a magnitude proportional to said first fluidic signal at said other frequencies; means for comparing said input signal and said third fluidic signal to generate a fluidic error signal; and actuator means responsive to said fluidic error signal and operably associated with said body for adjusting said rate of movement of the body in relation to said error signal.

Claim 6

A system as set forth in claim 3, wherein said delay circuit provides a phase shift in said fluidic acceleration signal of preselected value at said natural frequency without causing change in gain of said acceleration signal as a function of frequency.

Claim 7

A system as set forth in claim 4, wherein said delay circuit has a transfer function of (1-τS)/(1+τS), where τ is the time constant of said delay circuit and S is the Laplace Transform operator.

Claim 8

A system as set forth in claim 5, wherein said fluidic acceleration signal comprises a fluid pressure differential signal carried in a pair of conduits, said delay circuit including first flow resistances in each of said conduits, capacitance means for reducing the magnitude of said pressure differential signal passing through said first flow resistances, and a pair of feed-forward conduits communicating in crossing relation with said pair of conduits upstream and downstream of said first flow resistances, said feed-forward conduits each having second flow resistances therein providing flow resistance of approximately half the magnitude of said first flow resistances.

Claim 9

A system as set forth in claim 6, wherein said first flow resistances each comprise a pair of serially arranged flow restrictors, said second flow resistances each comprising a single flow restrictor, all said restrictors presenting approximately equal resistance to fluid flow.

Claim 10

A system as set forth in claim 7, wherein said capacitance means comprises a fluid flow accumulator having a flexible diaphragm traversing the interior thereof to define opposed first and second fluid chambers, said first and second chambers communicating with said pair of conduits at a position intermediate the associated pair of serially arranged restrictors.

Claim 12

A system as set forth in claim 9, wherein said first sensor means comprises a fluidic angular rate sensor developing a fluid pressure differential output signal whose magnitude is indicative of the magnitude and direction of rate of rotation of said body about said axis.

Claim 13

A system as set forth in claim 10, wherein said second sensor means comprises a fluidic, relatively undamped, spring mass accelerometer developing a fluid pressure differential output signal having a relatively large magnitude substantially only at said natural frequency.

Claim 14

A system as set forth in claim 11, wherein said accelerometer comprises said mass, a flexural pivot securing said mass to said body for permitting movement of said mass about said pivot in response to angular acceleration of said body about said predetermined axis, and a mechanical-to-fluidic transducer for generating said second pressure differential output signal in response to movement of said mass.

Claim 15

A system as set forth in claim 12, wherein said fluidic circuit means includes a delay circuit for adjusting the phase of said fluidic acceleration signal.

Claim 16

A system as set forth in claim 13, wherein said delay circuit has a transfer function of (1-τS)/(1+τS), where τ is the time constant of said delay circuit and S is the Laplace Transform operator.

Claim 17

A system as set forth in claim 14, wherein said fluidic acceleration signal comprises a fluid pressure differential signal carried in a pair of conduits, said delay circuit including first flow resistances in each of said conduits, capacitance means for reducing the magnitude of said pressure differential signal passing through said first flow resistances, and a pair of feed-forward conduits communicating in crossing relation with said pair of conduits upstream and downstream of said first flow resistances, said feed-forward conduits each having second flow resistances therein providing flow resistance of approximately half the magnitude of said first flow resistances.

Claim 18

A system as set forth in claim 13, wherein said first flow resistances each comprise a pair of serially arranged flow restrictors, said second resistances each comprising a single flow restrictor, all of said restrictors presenting approximately equal resistance to fluid flow.

Claim 19

A system as set forth in claim 16, wherein said capacitance means comprises a fluid flow accumulator having a flexible diaphragm traversing the interior thereof to define opposed first and second fluid chambers, said first and second chambers communicating with said pair of conduits at a position intermediate the associated pair of serially arranged restrictors.

Claim 20

A fluidic notch filter for filtering a fluidic output signal at the natural frequency of a body, comprising: a first sensor operably coupled with said body for generating a first fluidic output signal indicative of the rate of movement of said body in a preselected direction; a second sensor operably coupled with said body for generating a second fluidic output signal indicative of acceleration of said body in said preselected direction, said second sensor including means having a natural frequency approximately equal to the natural frequency of said body as said body moves in said direction; and fluidic circuit means for combining said first and second signals into a third output control signal having essentially zero magnitude upon movement of said body at said natural bending frequency in said direction, and having a magnitude correlated to the magnitude of said first output signal at other frequencies.

Claim 21

A fluidic notch filter for filtering a fluidic output signal at the natural frequency of a body, comprising: a first sensor operably coupled with said body for generating a first fluidic output signal indicative of the rate of movement of said body in a preselected direction; a second sensor operably coupled with said body for generating a second fluidic output signal indicative of acceleration of said body in said preselected direction, said second sensor including means having a natural frequency approximately equal to the natural frequency of said body as said body moves in said direction; and fluidic circuit means for combining said first and second signals into a third output control signal having essentially zero magnitude upon movement of said body at said natural bending frequency in said direction, and having a magnitude correlated to the magnitude of said first output signal at other frequencies.

Claim 22

A notch filter as set forth in claim 18, wherein said fluidic circuit means includes a delay circuit for adjusting the phase of said fluidic acceleration signal.

Claim 23

A notch filter as set forth in claim 19, wherein said delay circuit provides a phase shift in said fluidic acceleration signal of preselected value at said natural frequency without causing change in gain of said acceleration signal as a function of frequency.

Claim 24

A notch filter as set forth in claim 20, wherein said delay circuit has a transfer function of (1-τS)/(1+τS), where τ is the time constant of said delay circuit and S is the LaPlace Transform operator.

Claim 25

A notch filter as set forth in claim 21, wherein said fluidic acceleration signal comprises a fluid pressure differential signal carried in a pair of conduits, said delay circuit including first flow resistances in each of said conduits, capacitance means for reducing the magnitude of said pressure differential signal passing through said first flow resistances, and a pair of feed-forward conduits communicating in crossing relation with said pair of conduits upstream and downstream of said first flow resistances, said feed-forward conduits each having second flow resistances therein providing flow resistance of approximately half the magnitude of said first flow resistances.

Claim 26

A fluidic stabilization system for controlling rotation of a body about a preselected axis, wherein said body has a natural bending frequency about said axis, comprising: a source of pressurized fluid; a reservoir; a fluid actuator operably coupled to rotate said body about said axis; valve means for controlling fluid flow between said source, reservoir and actuator; means for developing a first fluid pressure differential signal indicative of a desired rate of rotation of said body; fluidic sensor means for developing a second fluid pressure differential signal indicative of actual rate of rotation of said body; fluidic comparator means responsive to said first and second signals for generating a fluid pressure differential error signal for operating said valve means to substantially equalize said actual and desired rates of rotation; and fluidic notch filter means operably associated with said sensor means for attenuating said second signal substantially only at said natural frequency, said filter means including a relatively under damped, fluidic spring mass accelerometer generating a fourth pressure differential output signal of magnitude approximately equal to said second signal substantially only at said natural frequency, said accelerometer operably coupled to said body to generate said fourth signal in relation to angular acceleration of the body about said axis, said filter further including means for adjusting the phase of said fourth signal to substantially cancel said second signal at said natural frequency.

Claim 27

A fluidic stabilization system for controlling rotation of a body about a preselected axis, wherein said body has a natural bending frequency about said axis, comprising: a source of pressurized fluid; a reservoir; a fluid actuator operably coupled to rotate said body about said axis; valve means for controlling fluid flow between said source, reservoir and actuator; means for developing a first fluid pressure differential signal indicative of a desired rate of rotation of said body; fluidic sensor means for developing a second fluid pressure differential signal indicative of actual rate of rotation of said body; fluidic comparator means responsive to said first and second signals for generating a fluid pressure differential error signal for operating said valve means to substantially equalize said actual and desired rates of rotation; and fluidic notch filter means operably associated with said sensor means for attenuating said second signal substantially only at said natural frequency, said filter means including a relatively under damped, fluidic spring mass accelerometer generating a fourth pressure differential output signal of magnitude approximately equal to said second signal substantially only at said natural frequency, said accelerometer operably coupled to said body to generate said fourth signal in relation to angular acceleration of the body about said axis, said filter further including means for adjusting the phase of said fourth signal to substantially cancel said second signal at said natural frequency.