Robust Control Design for pH Neutralization Uncertainty

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Solution Overview

Problem

Traditional control strategies for chemical processes, such as pH neutralization, face challenges due to nonlinearity, time delays, and unknown process parameters, leading to instability and performance degradation when operating conditions deviate from nominal values.

Innovation Solution

A robust control design approach that accounts for uncertainties by identifying a nominal process model, linearizing it at different pH values, and designing a controller with parameters that ensure stability and performance across a range of conditions, using multiplicative uncertainty analysis and feedback systems to validate and deploy the controller in a closed-loop system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional control strategies are used for pH neutralization processes, then the controller can be simple to implement, but the controller becomes unstable and performance degrades when operating conditions deviate from nominal values

Engineering Contradiction:
Improvecontroller stabilityVSAvoidcontroller design complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies dynamics by making the controller adaptive to changing operating conditions. The controller design is validated across multiple operating points (different pH values) rather than being fixed for a single nominal condition. This allows the controller to maintain stability and performance when operating conditions deviate from nominal values, resolving the contradiction between reliability under varying conditions and design complexity.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter validation approach by testing controller performance across a range of pH values (different operating conditions) rather than relying on a single nominal operating point. This parameter-based validation ensures the controller maintains reliability under varying conditions while managing design complexity through systematic validation procedures.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If a controller is designed for nominal operating conditions only, then the design process is simple, but the controller performance degrades when operating conditions change

Engineering Contradiction:
Improvecontroller performance across operating conditionsVSAvoidcontroller validation complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by validating the controller design beforehand across multiple operating points (different pH values) before deployment. This preliminary validation ensures adaptability to varying operating conditions while managing validation complexity through a systematic approach that tests the controller at discrete pH values to confirm performance across the operating range.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If robust control design accounting for uncertainties is implemented, then controller reliability improves under varying conditions, but the design and validation process becomes more complex

Engineering Contradiction:
Improvecontroller robustnessVSAvoiddesign process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the validation process into discrete steps: identifying a nominal process model, linearizing at different pH values to identify multiple transfer functions, and validating at each operating point. This segmented approach builds robustness incrementally, improving reliability under varying conditions while managing design process complexity through systematic, manageable validation stages.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3172629B1Robust control design approach for chemical processing industries and other industries
Publication Date: 2020.10.28 HONEYWELL INTERNATIONAL INC
  • EP3172629B1 patent drawingFigure 1
  • EP3172629B1 patent drawingFigure 2~3
  • EP3172629B1 patent drawingFigure 4~6

AI summary

A method includes obtaining (204) a process model (302, 402, 504) representing an industrial process (100, 600) and obtaining (206) controller specifications for an industrial process controller (106, 114, 122, 130, 138, 502, 614). The method also includes identifying (208) a controller design having one or more parameters for the industrial process controller using the process model, an uncertainty (304, 404, 506) associated with the process model, and the one or more parameters. The method further includes validating (210) the controller design of the industrial process controller for use in a closed-loop control system and deploying (212) the controller design if validated to the industrial process controller.