WO1999023386A1 - Peristaltic pump controller with nonlinear pump calibration coefficient - Google Patents
Peristaltic pump controller with nonlinear pump calibration coefficient Download PDFInfo
- Publication number
- WO1999023386A1 WO1999023386A1 PCT/US1998/022019 US9822019W WO9923386A1 WO 1999023386 A1 WO1999023386 A1 WO 1999023386A1 US 9822019 W US9822019 W US 9822019W WO 9923386 A1 WO9923386 A1 WO 9923386A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- pump
- inlet
- value
- flow rate
- controller
- Prior art date
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
- F04B49/06—Control using electricity
- F04B49/065—Control using electricity and making use of computers
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B43/00—Machines, pumps, or pumping installations having flexible working members
- F04B43/12—Machines, pumps, or pumping installations having flexible working members having peristaltic action
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B2203/00—Motor parameters
- F04B2203/02—Motor parameters of rotating electric motors
- F04B2203/0209—Rotational speed
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B2205/00—Fluid parameters
- F04B2205/01—Pressure before the pump inlet
Definitions
- the invention relates to peristaltic pumping systems and methods.
- the calibration factor takes into account the physical characteristics of the pump and associated tubing. Pressure present at the inlet of the pump also affects pump performance.
- the inlet pressure can range from a negative to a positive number and significantly alter the ratio of fluid volume per pump revolution to a greater extent than other variables affecting pump performance. Maintaining accuracy over a wide range of inlet pressures is a worthy objective, but one that has proven difficult to achieve in a practical manner.
- the invention provides an accurate, yet straightforward way of accurately controlling the speed of a peristaltic pump to achieve a desired flow rate over a wide range of positive and nega- tive inlet pump pressures.
- the invention provides a pump calibration coefficient k, which varies as a function of inlet pressure to maintain an accurate correlation between fluid volume displaced per pump revolution.
- the pump calibration coeffi- cient provided by the invention does not vary with inlet pressure in a continuous, linear way. Instead, the pump calibration coefficient varies as a non-linear, discontinuous function of inlet pump pressure.
- the invention defines zones of inlet pressure, in which zones the value of the pump calibration coefficient does not vary, but between which zones .the value of pump calibration coefficient changes as a step function.
- the step function can be expressed in a look-up table for- mat, in which values of the pump calibration coefficient over a wide range of positive and negative inlet pressures can be listed, to aid in commanding pump speeds to achieve desired fluid flow rates.
- Fig. 1 is a schematic view of a peristal- tic pumping system including a command module that generates a pump control command based upon a pump calibration coefficient, which varies as a step function according to pressure sensed at the pump inlet;
- Fig. 2 is a diagrammatic view of the step function by which the pump calibration coefficient of Fig. 1 is derived, showing the division of the operating range of positive and negative inlet pump pressures into pressure zones, in which zones the value of the pump calibration coefficient does not vary, but between which zones the value of pump calibration coefficient changes as a step function;
- Fig. 3 is a diagrammatic view of the step function shown in Fig. 2, with buffer margins established between the pressure zones;
- Fig. 4 shows a representative family of characteristic curves for a given operational pump configuration, showing , for each of the commanded rotational rates (30 RPM, 60 RPM, and 100 RPM) , the change of the flow rate-to-rotational rate percentage ratio (plotted on the Y-axis) in relation to variations in inlet pressure (plotted along the X-axis) ;
- Fig. 5 shows a representative family of curves, which represents the average of the linear fits and range of variation at 30 RPM, 60 RPM, and 100 RPM for six similar configurations of like pumps, driven in both clockwise and counter-clock- wise rotational directions, demonstrating substantially similar slopes and y-intercepts as the family of curves in Fig. 4;
- Fig. 6 shows a representative family of curves, which represents the average of the linear fits and range of variation at 30 RPM, 60 RPM, and 100 RPM for six dissimilar configurations of like pumps, driven in both clockwise and counter-clockwise rotational directions, demonstrating substantially similar slopes and y-intercepts as the family of curves in Figs. 4 and 5;
- Fig. 7 is a plot of a continuous calibration efficient, based upon the similar slopes and y-intercepts as the family of curves in Figs. 4, 5, and 6, by which a pump rotational rate can be continuously adjusted by a linear calibration factor within an operational range of inlet pressures to achieve a desired flow rate;
- Fig. 8 is an overlay of the four nominal inlet pressure zones, defined based upon expected operational conditions, upon the pump calibration curve shown in Fig. 7, through which a discrete calibration value is selected for each nominal inlet pressure zone;
- Fig. 9 is a flow chart showing an algo- rith for implementing a pressure margin that mediates against frequent changes in the discrete calibration value if sensed inlet pressure is close to the threshold between two defined nominal pressure zones; and Fig. 10 is a plot of normalized commanded flow rate for a pump at a pump speed of 100 RPM (expressed on the Y-axis as a percent of flow rate over 100 RPM) versus actual flow rate for the pump at inlet pressures between -50 mmHg and 250 mmHg (X-axis) , when the pump commands were adjusted using discrete calibration factors which vary as a step function on inlet pressure, showing actual flow rate remaining essentially at the normalized commanded flow rate.
- Fig. 1 shows a peristaltic pumping system 10, which embodies the features of the invention.
- the system 10 includes a peristaltic pump 12.
- the pump 12 can be used for processing various fluids.
- the pump 12 is particularly well suited for processing whole blood and other suspensions of biological cellular materials.
- the pump 12 includes a peristaltic pump rotor assembly 14 driven by a motor 16.
- motors 16 can be used, e.g. , a brushle ⁇ s D.C. motor.
- the rotor assembly 14 includes a pair of diametrically spaced rollers 18. In use, the rollers 18 engage flexible tubing 20 against an associated pump race 22. An inlet line 24 and an outlet line 26 join the tubing 20. When rotated, the rollers 18 to press against and urge fluid through the tubing 20, establishing flow between the inlet and outlet lines 24 and 26 at a desired flow rate Q. This peristaltic pumping action is well known.
- a pump motor controller 28 controls power to the pump motor 16.
- the controller 28 sends command signals to maintain a desired pump speed S (expressed in revolutions per minute) based upon a desired fluid flow rate Q (in ml/min) through the pump tubing 20.
- the relationship between the desired fluid flow rate Q and the command pump speed S is expressed as follows:
- the pump calibration coeffi- cient k is a function, in part, of the dimension and physical characteristics of the pump tubing 20, as well as the dimension and physical characteristics of the pump rotor assembly 1 . These dimensional and physical relationships can be readily determined empirically.
- the system 10 shown in Fig. 1 includes a sensor 30 to sense pressure P ( in the inlet line 24.
- the system 10 also includes a command module 32 coupled to the pump motor controller 28 and the sensor 30.
- the command module 32 receives, among other inputs to be described later, the inlet pressure P ( sensed by the sensor 30 during operation of the pump rotor assembly 14.
- the command module 32 generates a pump speed command 34 based, in part, upon the P ⁇ sensed by the sensor 30.
- C R is a factor relating to the dimension and physical characteristics of the pump rotor assembly 14.
- S pi is a nonlinear scale factor, derived in accordance with a step function 36 (expressed as f (P j )in Fig. 1).
- the characteristics C ⁇ and C R are empiri- cally determined for the pump rotor assembly 14 and the pump tubing 20. Once empirically determined, they together comprise a set value K (T R) , which the command module 32 receives as input (as Fig. 1 shows) .
- the command module 32 treats K (T R) as an essentially constant value in all zones of positive or negative pressures.
- the command module 32 computes the value of the scale factor S pj according to the step function 36, depending upon where the inlet pressure P i sensed by the sensor 30 lays with respect to a number (N) of predefined inlet pressure zones Z(N). More particularly, the step function 36 provides a scale factor S pj that equals a first nonvariable value X(l) when P s lays in a first defined zone of positive or negative pressures Z(l), and equals a second nonvariable value X(2) , different than the first nonvariable value X(l) , when P ; lays in a second defined zone of positive or negative pressures Z(2) different than Z(l).
- Fig. 2 graphically shows the step function 36 which determines of S pj .
- the scale factor S pj comprises a different, nonvariable value (designated X(l) to X(4)).
- the values X(l, 2, 3, 4) change as a non-linear step function.
- the boundaries of the pressure zones Z(N) and the associated scale factors X(N) can be empirically defined for a given pump in a manner described in greater detail later.
- the command module 32 can store the step function 36 of S pj depicted in Fig. 2 in look-up table format, which Table 1 exemplifies.
- Table 1 Look Up Table for S pi
- the command module 32 also receives as input the desired flow rate Q.
- the command module 32 generates as the command output 34 to the pump motor controller 28, the desired pump speed S, which the command module 32 derives as follows:
- the command module 32 preferably incorporates buffer margins PMAR (mmHg) .
- the buffer margins PMAR are established above and below the transitions between the zones Z(l, 2, 3, 4).
- Fig. 3 diagrammatically illustrates the presence of the buffer margins PMAR.
- the buffer margins in effect, broaden the boundaries between the zones Z (1, 2, 3, 4).
- the command module 32 derives S pj as follows:
- EXAMPLE A set of scale factors S pj was derived for a peristaltic pump of the type shown in Chapman U.S. Patent 5,462,417.
- the pump tubing for the pump was coupled to a cassette, also shown and described in Chapman U.S. Patent 5,462,417, which consolidated pressure sensing and liquid flow valving functions. Further details of the construction of the pump and cassette are not material to this invention, but can be found in Chapman U.S. Patent 5,462,417, which is incorporated herein by reference.
- Six pumps of the type shown in Chapman U.S. Patent 5,462,417 were evaluated in association with different cassettes, to determine the effect of variation of inlet pressure upon liquid flow rate, given a constant rate of pump rotor rotation.
- Fig. 4 shows a representative family of characteristic curves for a given pump-cassette association.
- Fig. 4 shows, for each of the commanded rotational rates (30 RPM, 60 RPM, and 100 RPM) , the change of the flow rate-to-rotational rate percentage ratio (plotted on the Y-axis) in relation to variations in inlet pressure (plotted along the X-axis) .
- Fig. 4 shows, for each of the commanded rotational rates (30 RPM, 60 RPM, and 100 RPM) , the change of the flow rate-to-rotational rate percentage ratio (plotted on the Y-axis) in relation to variations in inlet pressure (plotted along the X-axis) .
- Figs. 4, 5, and 6 demonstrate that the overall offsets and slopes of the multiple families of curves for the multiple pump-cassette associations evaluated do not vary significantly.
- An average for all families of curves for the multiple pump-cassette associations evaluated can be linearized and expressed with the following slope/y-intercept function:
- Ra teRa ti o ( % ) 97. 38 + 0. 207 ( P j . ) ( 4 )
- RateRa tio ( % ) Sensed
- Figs. 4, 5, and 6 also demonstrate that, among the variables affecting pump performance, the factor having the most significant effect is the inlet pressure. Effects on the variance of flow rate versus commanded pump rate due to the range of pump rate commands, pump rotational direction, variations in pump tubing and associated flow tubing (e.g. , the cassette) , and outlet pump pressure are insignificant compared to the effect of inlet pump pressure in commanding a precise flow rate.
- the rotational rate can be adjusted by a linear calibration factor for the operational range of inlet pressures to achieve a desired flow rate.
- Fig. 7 shows the plot of this continuous calibration efficient, based upon the relationship expressed in Equation (4) .
- discrete calibration factors can be defined for discrete pres- sure ranges.
- nominal zones of expected operational pressure conditions are defined.
- the nominal zones characterize (i) a low vacuum (negative pressure) condition (e.g., under - 50 mmHg); (ii) a transitional ambient negative to positive pressure condition (e.g., -50 mmHg to 100 mmHg); (iii) a low range of positive pressure conditions (e.g., 100 mmHg to 230 mmHg) ; and (iv) a high range of positive pressure conditions (e.g., above 230 mmHg).
- fewer or more nominal zones can be de- fined, depending upon criteria that the operator believes are most relevant to the operation and objectives of the particular system.
- Fig. 8 shows the overlay of the four nominal zones defined in the preceding paragraph on the pump calibration curve shown in Fig. 7.
- a discrete calibration value is selected for each nominal zone.
- the rationale for selecting a discrete value in each nominal zone can vary. For example, in zones (ii) and (iii) , which encompass the normal expected operational conditions, the selected discrete values correspond generally with in the mid-values of the continuous coefficient in the respective zones. For zones (i) and (iv) , which encompass less normal operational conditions, the selected discrete values generally correspond to the values of the continuous coefficient laying in the first 20% to 30% of the zone, where operational conditions experienced are most likely to occur.
- PMAR equal to 20 mmHg is selected, to prevent frequent shifting between the selected discrete values when sensed inlet pressure is close to two nominal zones.
- Other values for PMAR can be selected based upon criteria that the operator believes are most relevant to the operation and objectives of the particular system.
- a look up table of different, non variable discrete scale factor values S . for the nominal zones (i) to (iv) selected for the system can be created, as follows:
- an algorithm 40 evaluates a subsequently sensed value of P ⁇ to determine its proximity to the upper and lower pressure thresholds for the current S .. If the current P j is more than 20 mmHg above the upper pressure threshold of the current zone, then a new S . is selected from Look Up Table 2, otherwise S . remains unchanged until P j is sensed again. Likewise, if the current P. is more than 20 mmHg below the lower threshold of the current zone, then a new S . is selected from Look Up Table 2, otherwise S . remains unchanged until P ( is sensed again.
- Fig. 10 demonstrates that the actual flow rate remains essentially at the normalized commanded flow rate (100%) in this inlet pressure region, which reflects typical expected operational conditions for blood process- ing.
- Fig. 10 also shows a plot 44 of the estimated flow rate, when not adjusted by S . , against the normalized commanded flow rate.
- Fig. 10 demonstrates that improved, accurate results are achieved by the use of discrete scale factors S . , which vary as step function over discrete pump inlet pressure ranges.
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Abstract
Description
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Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP98953692A EP1027539A4 (en) | 1997-10-30 | 1998-10-19 | Peristaltic pump controller with nonlinear pump calibration coefficient |
CA002306230A CA2306230A1 (en) | 1997-10-30 | 1998-10-19 | Peristaltic pump controller with nonlinear pump calibration coefficient |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/960,676 US5947692A (en) | 1997-10-30 | 1997-10-30 | Peristaltic pump controller with scale factor that varies as a step function of pump inlet pressure |
US08/960,676 | 1997-10-30 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1999023386A1 true WO1999023386A1 (en) | 1999-05-14 |
Family
ID=25503472
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1998/022019 WO1999023386A1 (en) | 1997-10-30 | 1998-10-19 | Peristaltic pump controller with nonlinear pump calibration coefficient |
Country Status (4)
Country | Link |
---|---|
US (1) | US5947692A (en) |
EP (1) | EP1027539A4 (en) |
CA (1) | CA2306230A1 (en) |
WO (1) | WO1999023386A1 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2014041361A1 (en) * | 2012-09-14 | 2014-03-20 | Vapourtec Limited | Peristaltic pump and method of controlling a peristaltic pump |
WO2014137809A1 (en) * | 2013-03-04 | 2014-09-12 | Bayer Medical Care Inc. | Methods and systems for dosing control in an automated fluid delivery system |
US10610632B2 (en) | 2014-12-10 | 2020-04-07 | B. Braun Avitum Ag | Method and control apparatus for determining and adjusting a flow rate of a blood delivery pump |
US12005167B2 (en) | 2017-07-10 | 2024-06-11 | Fresenius Medical Care Deutschland Gmbh | Method and devices for the calibration of a pump for the blood treatment |
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US5402290A (en) * | 1993-06-14 | 1995-03-28 | Seagate Technology, Inc. | One piece limit stop for disc drive |
US7006896B1 (en) * | 1999-10-13 | 2006-02-28 | Graco Minnesota Inc. | Sealant dispensing correction method |
ITTO20011222A1 (en) * | 2001-12-27 | 2003-06-27 | Gambro Lundia Ab | BLOOD FLOW CONTROL EQUIPMENT IN A BLOOD CIRCUIT-EXTRA-BODY. |
CN100557236C (en) * | 2002-10-23 | 2009-11-04 | 开利商业冷藏公司 | Fluid distributor calibration system and method |
EP1780411A3 (en) * | 2002-10-23 | 2010-01-27 | Carrier Commercial Refrigeration, Inc. | Fluid dispenser calibration system and method |
US6986441B2 (en) * | 2002-10-23 | 2006-01-17 | Carrier Commercial Refrigeration, Inc. | Fluid dispenser calibration system and method |
US7299944B2 (en) * | 2002-11-21 | 2007-11-27 | Carrier Commercial Refrigeration, Inc. | Fluid dispenser calibration system and method |
DE10354205A1 (en) * | 2003-11-20 | 2005-06-23 | Leybold Vakuum Gmbh | Method for controlling a drive motor of a vacuum displacement pump |
DE102005023430A1 (en) * | 2005-03-15 | 2006-09-21 | Fresenius Medical Care Deutschland Gmbh | Method and device for determining the effective delivery rate or setting the speed of a peristaltic pump |
ES2348407T3 (en) * | 2005-05-18 | 2010-12-03 | Gambro Lundia Ab | APPLIANCE TO CONTROL THE BLOOD FLOW IN AN EXTRACORPORE CIRCUIT. |
US11906988B2 (en) | 2006-03-06 | 2024-02-20 | Deka Products Limited Partnership | Product dispensing system |
US9146564B2 (en) | 2006-03-06 | 2015-09-29 | Deka Products Limited Partnership | Product dispensing system |
US11214476B2 (en) | 2006-03-06 | 2022-01-04 | Deka Products Limited Partnership | System and method for generating a drive signal |
US7740152B2 (en) * | 2006-03-06 | 2010-06-22 | The Coca-Cola Company | Pump system with calibration curve |
US8353864B2 (en) | 2009-02-18 | 2013-01-15 | Davis David L | Low cost disposable infusion pump |
US8197235B2 (en) | 2009-02-18 | 2012-06-12 | Davis David L | Infusion pump with integrated permanent magnet |
CN103354800B (en) * | 2011-01-05 | 2019-10-18 | 菲兹研究有限公司 | Flow measuring apparatus |
CN105257518B (en) * | 2015-10-15 | 2017-09-26 | 深圳市清时捷科技有限公司 | A kind of accurate quantification calibration method of peristaltic pump and peristaltic pump |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4392849A (en) * | 1981-07-27 | 1983-07-12 | The Cleveland Clinic Foundation | Infusion pump controller |
US4468219A (en) * | 1983-12-20 | 1984-08-28 | International Business Machines Corporation | Pump flow rate compensation system |
US4820281A (en) * | 1987-05-21 | 1989-04-11 | Ivy Medical, Inc. | Drop volume measurement system |
-
1997
- 1997-10-30 US US08/960,676 patent/US5947692A/en not_active Expired - Lifetime
-
1998
- 1998-10-19 CA CA002306230A patent/CA2306230A1/en not_active Abandoned
- 1998-10-19 WO PCT/US1998/022019 patent/WO1999023386A1/en not_active Application Discontinuation
- 1998-10-19 EP EP98953692A patent/EP1027539A4/en not_active Withdrawn
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4392849A (en) * | 1981-07-27 | 1983-07-12 | The Cleveland Clinic Foundation | Infusion pump controller |
US4468219A (en) * | 1983-12-20 | 1984-08-28 | International Business Machines Corporation | Pump flow rate compensation system |
US4820281A (en) * | 1987-05-21 | 1989-04-11 | Ivy Medical, Inc. | Drop volume measurement system |
Non-Patent Citations (1)
Title |
---|
See also references of EP1027539A4 * |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2014041361A1 (en) * | 2012-09-14 | 2014-03-20 | Vapourtec Limited | Peristaltic pump and method of controlling a peristaltic pump |
WO2014137809A1 (en) * | 2013-03-04 | 2014-09-12 | Bayer Medical Care Inc. | Methods and systems for dosing control in an automated fluid delivery system |
US9109591B2 (en) | 2013-03-04 | 2015-08-18 | Bayer Medical Care Inc. | Methods and systems for dosing control in an automated fluid delivery system |
CN105025952A (en) * | 2013-03-04 | 2015-11-04 | 拜耳医疗保健股份有限公司 | Methods and systems for dosing control in an automated fluid delivery system |
US9375528B2 (en) | 2013-03-04 | 2016-06-28 | Bayer Healthcare Llc | Methods and systems for dosing control in an automated fluid delivery system |
EP2964290A4 (en) * | 2013-03-04 | 2016-10-19 | Bayer Healthcare Llc | Methods and systems for dosing control in an automated fluid delivery system |
US9682192B2 (en) | 2013-03-04 | 2017-06-20 | Bayer Healthcare Llc | Methods and systems for dosing control in an automated fluid delivery system |
US10610632B2 (en) | 2014-12-10 | 2020-04-07 | B. Braun Avitum Ag | Method and control apparatus for determining and adjusting a flow rate of a blood delivery pump |
US12005167B2 (en) | 2017-07-10 | 2024-06-11 | Fresenius Medical Care Deutschland Gmbh | Method and devices for the calibration of a pump for the blood treatment |
Also Published As
Publication number | Publication date |
---|---|
US5947692A (en) | 1999-09-07 |
EP1027539A4 (en) | 2002-02-06 |
EP1027539A1 (en) | 2000-08-16 |
CA2306230A1 (en) | 1999-05-14 |
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