Adaptive Nonlinear Controller for Process Stability

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Solution Overview

Problem

Current control methods for nonlinear systems, such as PID controllers and model predictive control, face challenges with stability and effectiveness due to model inaccuracies and parameter drifts, leading to oscillations and reduced performance in maintaining consistent product quality, especially in batch and continuous processes.

Innovation Solution

An adaptive nonlinear control algorithm is developed, which includes configuring a controller using a state-space model, transforming it into controllable canonical equations, and minimizing an objective function to select optimal control parameters, allowing for dynamic control and stability analysis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If PID control is used for nonlinear systems, then the system can be controlled around a predetermined operating point, but the control effectiveness deteriorates when parameters drift due to nonlinear nature or component changes

Engineering Contradiction:
Improvecontrol stabilityVSAvoidparameter drift adaptation
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic adaptation by continuously updating controller parameters based on real-time system state. The adaptive controller modifies gain parameters online to track changes in system characteristics, transforming the static PID controller into a dynamic system that automatically adjusts to parameter drift and nonlinear behavior.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes controller parameters dynamically based on system operating conditions. The adaptive algorithm modifies proportional, integral, and derivative gains according to real-time measurements of system state and parameter drift, enabling the controller to maintain effectiveness across varying operating points and conditions.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If linearization is performed around operating point, then PID controller design becomes feasible, but the linearized model becomes inaccurate when system parameters drift

Engineering Contradiction:
Improvecontroller design simplicityVSAvoidmodel accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent maintains the simplicity of linearized controller design while compensating for model inaccuracy through dynamic parameter adaptation. The controller structure remains based on linearization principles for ease of design, but the parameters are continuously adjusted online to account for nonlinear effects and parameter drift, effectively decoupling design simplicity from operational accuracy.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements feedback mechanisms that monitor system response and use this information to adjust controller parameters. The adaptive algorithm continuously compares actual system behavior with predicted behavior from the linearized model and modifies parameters to compensate for model inaccuracies, maintaining high effectiveness without requiring complex nonlinear model identification.

Inventive Principle:
Principle #23Feedback

3Manufacturing precision

If control gains are tuned manually, then desired closed loop response can be achieved, but re-adjustment is required when parameters drift, increasing operational complexity

Engineering Contradiction:
Improveclosed loop response qualityVSAvoidgain tuning maintenance
Core Design Contradiction:
Manufacturing precisionVSEase of operation

Solution Approach 1:

The patent implements self-service by enabling the controller to automatically adjust its own parameters without external intervention. The adaptive algorithm continuously monitors system performance and autonomously modifies gain parameters to maintain optimal closed-loop response, eliminating the need for manual re-tuning when parameters drift and significantly reducing operational complexity.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent uses feedback from system performance measurements to automatically adjust control gains. The adaptive controller continuously monitors closed-loop response quality and uses this feedback to modify parameters, replacing manual tuning operations with automated feedback-driven adjustment that maintains response quality without increasing operational burden.

Inventive Principle:
Principle #23Feedback

4Adaptability or versatility

If adaptive nonlinear control is implemented, then stability and adaptability are improved, but device complexity increases

Engineering Contradiction:
Improveparameter drift compensationVSAvoidcontroller structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent achieves adaptive nonlinear control primarily through parameter changes rather than structural modifications. The controller maintains a relatively simple structure while dynamically adjusting gain parameters based on system state, achieving high adaptability to parameter drift and nonlinear behavior without proportionally increasing device complexity.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces dynamics into the controller parameters rather than the controller structure. By making parameters time-varying and state-dependent while maintaining a straightforward controller architecture, the system achieves enhanced adaptability and nonlinear compensation capabilities with minimal increase in overall system complexity.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS10346736B2Systems and methods for adaptive non-linear control of process systems
Publication Date: 2019.07.09 HUNTE KYLE
  • US10346736B2 patent drawing
  • US10346736B2 patent drawing
  • US10346736B2 patent drawing

AI summary

The invention provides systems and methods for generating an adaptive nonlinear controller and utilizing the adaptive nonlinear controller to regulate the operation of nonlinear process systems. In particular, a method is provided for generating a control model by defining an objective function utilizing a target function that specifies the desired response of the system and a state-space model representing the dynamics of the non-linear system. When executed by a controller the control model causes the regulated system to operate as specified by the target function and thereby produce a product that is consistent with various prescribed quality metrics.