Field Device Digital Filter Coefficient Calculation

Solution Overview

Problem

Current methods for implementing custom digital filters in process control systems are cumbersome and prone to errors, requiring manual calculation and entry of coefficients, making it impractical for dynamic changes in filter characteristics, especially in real-time process conditions.

Innovation Solution

Implementing a digital filter design algorithm, such as the Parks-McClellan algorithm, within a process control field device or equipment, where filter design parameters can be exposed via an interface and calculated automatically, allowing for dynamic updates of filter coefficients based on process conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If manual calculation and entry of filter coefficients is used, then implementation of custom digital filters is possible, but the process is cumbersome and prone to errors

Engineering Contradiction:

Improveaccuracy of filter coefficient implementationVSAvoidease of implementing custom digital filters

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The field device performs self-configuration by automatically calculating filter coefficients based on process variables and filter specifications, eliminating the need for manual coefficient calculation and entry. The device serves itself by integrating the filter design algorithm internally, allowing it to generate and apply filter coefficients autonomously.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The manual mechanical process of calculating and entering coefficients is replaced by an automated computational system. The field device uses embedded processing power to execute filter design algorithms, substituting human operators with automated electronic computation to generate and apply filter coefficients.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If manual calculation and entry of filter coefficients is used, then custom digital filters can be implemented, but dynamic changes in filter characteristics become impractical

Engineering Contradiction:

Improveability to change filter characteristics dynamicallyVSAvoidtime required for manual coefficient updates

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The filter characteristics are made dynamic by enabling real-time adjustment of filter parameters based on changing process conditions. The field device continuously monitors process variables and automatically recalculates filter coefficients as needed, allowing the filter to adapt dynamically without manual intervention.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The field device pre-configures itself with the necessary filter design algorithms and computational capabilities, so when dynamic changes are needed, the coefficients can be recalculated immediately using available process data, eliminating the time loss associated with manual reconfiguration.

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If filter coefficients are manually entered, then implementation is possible, but errors are prone and manual effort is high

Engineering Contradiction:

Improveease of implementing filter functionalityVSAvoiderror-free implementation of filter coefficients

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The field device performs self-configuration by automatically calculating filter coefficients based on process variables and filter specifications, eliminating the need for manual coefficient calculation and entry. The device serves itself by integrating the filter design algorithm internally, allowing it to generate and apply filter coefficients autonomously.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The manual mechanical process of calculating and entering coefficients is replaced by an automated computational system. The field device uses embedded processing power to execute filter design algorithms, substituting human operators with automated electronic computation to generate and apply filter coefficients.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS8301676B2Field device with capability of calculating digital filter coefficients

Publication Date: 2012.10.30 FISHER ROSEMOUNT SYST INC

AI summary

A digital filter design algorithm is implemented directly within a process control field device or other process related equipment. Filter design parameters are exposed so that filter design parameter values may be provided to the digital filter design algorithm so that the digital filter design algorithm may calculate digital filter coefficients for a digital filter having desired frequency response characteristics. The digital filter design parameter values may be provided by a user, or may be provided as process variable data output from a process control field device or other process related equipment. Once the coefficients of the digital filter having the desired frequency response characteristics have been calculated, the digital filter may be applied to process variable data received by the process control field device or other process related equipment.