Servo control system for a reciprocating piston respirator
First Claim
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1. A system for generating predetermined flow characteristics in a reciprocating piston respirator by controlling movement of a piston comprising:
- detector means for generating a detected position signal indicative of a current actual position of said piston in said reciprocating piston respirator;
analysis means for using nonlinear, predictive servo control techniques employing said detected position signal to generate a control signal representative of a force sufficient to move said piston in said reciprocating piston respirator to a stored next position to produce said predetermined flow characteristics comprising;
logic means for using said nonlinear, predictive servo control techniques for performing time domain analysis of fictional, pressure and inertial factors affecting movement of said piston to predict said force required to move said piston to said next position through the use of program control means for generating position data representative of a plurality of position values which said piston must assume at a plurality of substantially equally spaced segment times to produce said predetermined flow characteristics;
means for generating said force sufficient to move said piston in said reciprocating piston respirator in response to said control signal comprising;
pulse-width modulation means for producing a digital representation of a required power signal which is substantially proportional to said force;
direction selection means for producing a digital direction signal which substantially represents a direction of motor rotation;
buffer means for converting said digital representation of said required power signal and said digital direction signal into a polarized electrical power signal which is substantially proportional to said force;
motor means for converting said polarized electrical power signal into rotational power; and
,piston displacement means for converting said rotational power into lateral movement of said piston.
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Abstract
A control system for moving a piston in a reciprocating piston respirator which utilizes predictive servo control techniques. Present invention uses nonlinear time domain analysis rather than linear frequency domain analysis to produce a predictive servo control system for precisely controlling the movement of a piston in a reciprocating piston respirator. A plurality of flow profiles can be produced using stored factor tables. Current pressure and position information are used in the predictive servo control system.
221 Citations
11 Claims
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1. A system for generating predetermined flow characteristics in a reciprocating piston respirator by controlling movement of a piston comprising:
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detector means for generating a detected position signal indicative of a current actual position of said piston in said reciprocating piston respirator; analysis means for using nonlinear, predictive servo control techniques employing said detected position signal to generate a control signal representative of a force sufficient to move said piston in said reciprocating piston respirator to a stored next position to produce said predetermined flow characteristics comprising; logic means for using said nonlinear, predictive servo control techniques for performing time domain analysis of fictional, pressure and inertial factors affecting movement of said piston to predict said force required to move said piston to said next position through the use of program control means for generating position data representative of a plurality of position values which said piston must assume at a plurality of substantially equally spaced segment times to produce said predetermined flow characteristics; means for generating said force sufficient to move said piston in said reciprocating piston respirator in response to said control signal comprising; pulse-width modulation means for producing a digital representation of a required power signal which is substantially proportional to said force; direction selection means for producing a digital direction signal which substantially represents a direction of motor rotation; buffer means for converting said digital representation of said required power signal and said digital direction signal into a polarized electrical power signal which is substantially proportional to said force; motor means for converting said polarized electrical power signal into rotational power; and
,piston displacement means for converting said rotational power into lateral movement of said piston.
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2. A system for precisely controlling movement of a piston in a reciprocating piston respirator to produce a selected flow profile of a variable output flow from said respirator comprising:
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motor means for inducing movement of said piston with a torque proportional to an average voltage applied to said motor means; means for deriving position data representative of a plurality of successive next positions said piston must assume to produce said selected flow profile; means for generating a plurality of successive detected position signals indicative of a plurality of successive current actual positions (Lnow) of said piston at a plurality of successive current segment times; means for successively comparing said detected position signals with said plurality of successive next positions to produce a plurality of difference distance signals; means for generating a torque control signal (T) corresponding to said torque required to move said piston to said plurality of successive next positions in response to said difference distance signals; pulse-width modulation means for pulse-width modulating a supply voltage in response to said torque control signal (T) to control said average voltage applied to said motor means. - View Dependent Claims (3, 4)
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5. A method of precisely controlling movement of a piston in a reciprocating piston respirator by controlling the average power supplied to an electric motor used to drive said piston to produce a preselected flow profile comprising the steps of:
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computing a plurality of position values of said piston at a plurality of segment times to produce said selected flow profile; detecting an actual position value corresponding to a actual position of said piston at a current segment time; determining a difference distance between said actual position value of said piston at each of said current segment times and said position value for a next segment time to produce a difference distance signal; generating a torque control signal indicative of a torque required to move said piston said difference distance; generating an average voltage to drive said electric motor with sufficient torque to move said piston said difference distance. - View Dependent Claims (6, 7, 8, 9, 10, 11)
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Specification