Linear servoactuator with integrated transformer position sensor
First Claim
1. An integrated servomechanism and position sensor apparatus, comprising:
- an actuator including a variably positionable magnetically permeable portion confined to move only within a predetermined space;
a split secondary transformer having a primary coil and a pair of spaced-apart secondary coils;
means for exciting said primary coil to produce a time-varying electromagnetic field within said predetermined space,movement of said magnetically permeable portion within said predetermined space coupling said electromagnetic field into said secondary coils;
circuit means connected to said secondary coils for providing a coil signal which varies as a function of the position of said magnetically permeable portion of said actuator;
means responsive to said coil signal for transforming said coil signal into an actual position signal which varies as function of the position of said actuator;
command position signal means for providing a desired position signal corresponding to a desired position for said actuator;
means for providing a driving signal as a function of the difference between said desired position signal and said actual position signal; and
actuator moving means responsive to said driving signal for generating an actuator driving force within said predetermined space for causing said actuator to move toward said desired position.
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Accused Products
Abstract
A linear servoactuator including an integrated split-secondary differential transformer position sensor and a fluid driven linear actuator controlled by solenoid poppet valves. Signals from the position sensor transformer are digitized and linearized by a control microcomputer by using digitized transformer signals as addresses for a programmable read only memory. The linearized output is compared to a command position to determine an error value. When the error reaches a predetermined magnitude, indicating that the actuator is approaching the command position, solenoid poppet valves are actuated by a pulse-width modulated signal from the microcomputer to progressively decrease the fluid flow to the actuator for deceleration.
196 Citations
25 Claims
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1. An integrated servomechanism and position sensor apparatus, comprising:
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an actuator including a variably positionable magnetically permeable portion confined to move only within a predetermined space; a split secondary transformer having a primary coil and a pair of spaced-apart secondary coils; means for exciting said primary coil to produce a time-varying electromagnetic field within said predetermined space, movement of said magnetically permeable portion within said predetermined space coupling said electromagnetic field into said secondary coils; circuit means connected to said secondary coils for providing a coil signal which varies as a function of the position of said magnetically permeable portion of said actuator; means responsive to said coil signal for transforming said coil signal into an actual position signal which varies as function of the position of said actuator; command position signal means for providing a desired position signal corresponding to a desired position for said actuator; means for providing a driving signal as a function of the difference between said desired position signal and said actual position signal; and actuator moving means responsive to said driving signal for generating an actuator driving force within said predetermined space for causing said actuator to move toward said desired position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A position sensor apparatus, comprising:
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a magnetically permeable member which is variably positionable within a predetermined space; a split secondary transformer having a primary coil positioned between a pair of spaced-apart secondary coils; means for exciting said primary coil to produce a time-varying electromagnetic field, said magnetically permeable member being operative to couple said electromagnetic field into one of said secondary coils at all positions within said predetermined space; circuit means connected to said secondary coils for providing a coil signal which varies in a nonlinear manner corresponding to the spatial position of said magnetically permeable member in said predetermined space; conversion means for converting said coil signal into digital address signals; programmed memory means for storing digital actual position signals corresponding to a linearized actual position of said magnetically permeable member in said predetermined space at addressable locations corresponding to said digital address signals; and means responsive to said digital address signals for reading said digital actual position signals from said memory means and for providing said digital actual position signals as an output signal incicative of the actual position of said magnetically permeable member within said predetermined space. - View Dependent Claims (14)
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15. A linear servomechanism apparatus, comprising:
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a fluid driven linear actuator including an axially variably positionable actuator rod having a magnetically permeable portion confined to move only within a predetermined space; a split secondary transformer having a primary coil positioned between a pair of spaced apart secondary coils; means for exciting said primary coil to produce a time-varying electromagnetic field within said predetermined space, movement of said magnetically permeable portion coupling said electromagnetic field into said secondary coils; circuit means connected to said secondary coils for providing a coil signal which varies as a function of the position of said actuator rod; means responsive to said coil signal for transforming said coil signal into an actual position signal which varies as a function of the axial position of said actuator; command position signal means for providing a desired position signal corresponding to a desired axial position for said actuator rod; error signal means for providing an error signal as a function of a difference between said desired position signal and said actual position signal; modulation means for providing a modulated actuator driving signal which varies as a function of the magnitude of said error signal, said driving signal comprising an on-portion and an off-portion; and valve means responsive to said driving signal for introducing pressurized fluid into said predetermined space to move said actuator rod during said on-portion of said driving signal and for blocking off said pressurized fluid from said predetermined space during said off-portion of said driving signal.
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16. An integrated servomechanism and position sensor apparatus, comprising:
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an actuator including a magnetically permeable portion which is variably positionable within a predetermined space; a split secondary transformer having a primary coil positioned between a pair of spaced-apart secondary coils; means for exciting said primary coil to produce a time-varying electromagnetic field, said magnetically permeable portion being operative to couple said electromagnetic field into said secondary coils at positions within said predetermined space; circuit means connected to said secondary coils for providing a coil signal which varies in a nonlinear manner corresponding to the spatial position of said magnetically permeable portion of said actuator; means responsive to said coil signal for transforming said coil signal into a linearized actual position signal which varies linearly as a function of the position of said actuator within said predetermined space; command position signal means for providing a desired position signal corresponding to a desired position for said actuator; means for providing a driving signal as a function of the difference between said desired position signal and said actual position signal; and actuator moving means responsive to said driving signal for causing said actuator to move toward said desired position.
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17. An integrated servomechanism and position sensor apparatus, comprising:
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an actuator including a variably positionable magnetically permeable portion confined to move only within a predetermined space; means for generating an actuator driving force within said predetermined space for moving said actuator and said magnetically permeable portion;
p1 electromagnetic coil means for sensing movement of said magnetically permeable portion within said predetermined space; andcontrol means responsive to said electromagnetic coil means for deriving position information of said actuator from movement of said magnetically permeable portion and for causing said actuator driving force generating means to move said actuator and said magnetically permeable portion toward a desired position. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25)
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Specification