System and method for filtering output in mass flow controllers and mass flow meters

• US 7,113,895 B2
• Filed: 08/26/2004
• Issued: 09/26/2006
• Est. Priority Date: 04/27/2001
• Status: Expired due to Fees

• Current Assignee: Brooks Instrument LLC (Illinois Tool Works Inc.)
• Original Assignee: Celerity Incorporated (ICHOR Holdings, Ltd.)
• Inventors: Tariq, Faisal
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): Washburn, Douglas N.
• Application Number:
  US10/926,860
• Publication Number:
  US 20050023197A1
• Time in Patent Office: 761 Days
• Field of Search: 702/189, 702/190
• US Class Current: 702/190
• CPC Class Codes: G05B 11/42 for obtaining a characteristic which is both proportional and time-dependent, e.g. P. I., P. I. D.
• CPC Class Codes: G05B 13/021 in which a variable is automatically adjusted to optimise the performance

Abstract

Embodiments of the present invention can include the steps of (i) filtering the indicated flow to derive an intermediate filtered indicated flow, (ii) deriving a weighted first derivative of the intermediate filtered indicated flow, and (iii) outputting a filtered indicated flow comprising the sum of the intermediate filtered indicated flow and the weighted first derivative of the intermediate filtered indicated flow. The indicated flow can be filtered using a FIR, an IIR a running average or other filtering scheme.

Claims

1. A method for filtering an indicated flow comprising:

filtering said indicated flow to derive an intermediate filtered indicated flow;

deriving a weighted first derivative of said intermediate filtered indicated flow; and

summing said intermediate filtered indicated flow and said weighted first derivative of said intermediate filtered indicated flow to derive a filtered indicated flow;

wherein said intermediate filtered indicated flow is derived using running average.

2. A method for filtering an indicated flow comprising:

filtering said indicated flow to derive an intermediate filtered indicated flow;

deriving a weighted first derivative of said intermediate filtered indicated flow; and

summing said intermediate filtered indicated flow and said weighted first derivative of said intermediate filtered indicated flow to derive a filtered indicated flow;

wherein said intermediate filtered indicated flow is derived using IIR.

3. A method for filtering an indicated flow comprising:

filtering said indicated flow to derive an intermediate filtered indicated flow;

deriving a weighted first derivative of said intermediate filtered indicated flow; and

summing said intermediate filtered indicated flow and said weighted first derivative of said intermediate filtered indicated flow to derive a filtered indicated flow;

wherein said intermediate filtered indicated flow is derived using FIR.

4. A system for filtering an indicated flow comprising a flow device operable to:

filter an indicated flow to derive an intermediate filtered indicated flow;

derive a weighted first derivative of said filtered indicated flow; and

derive a filtered indicated flow from a sum of said intermediate filtered indicated flow and said weighted first derivative of said intermediate filtered indicated flow;

wherein said intermediate filtered indicated flow is derived using running average.

5. A system for filtering an indicated flow comprising a flow device operable to:

filter an indicated flow to derive an intermediate filtered indicated flow;

derive a weighted first derivative of said filtered indicated flow; and

derive a filtered indicated flow from a sum of said intermediate filtered indicated flow and said weighted first derivative of said intermediate filtered indicated flow;

wherein said intermediate filtered indicated flow is derived using IIR.

6. A system for filtering an indicated flow comprising a flow device operable to:

filter an indicated flow to derive an intermediate filtered indicated flow;

derive a weighted first derivative of said filtered indicated flow; and

derive a filtered indicated flow from a sum of said intermediate filtered indicated flow and said weighted first derivative of said intermediate filtered indicated flow;

wherein said intermediate filtered indicated flow is derived using FIR.