Multivariable Process Control Using Convex Hull Operating Ranges

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Solution Overview

Problem

Existing multi-variable process control systems struggle to define independent operating ranges for process variables, which is crucial for ensuring product quality in pharmaceutical manufacturing processes.

Innovation Solution

A method is developed to derive a multi-dimensional representation of process variables, define a feasible region by selecting historical data points with in-specification product qualities, calculate the convex hull, and determine an interior hypercube within the convex hull to set independent operating ranges for process variables.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If dynamic control with interdependent variable ranges is used, then process flexibility and optimization are improved, but ease of operation and independent variable control deteriorate

Engineering Contradiction:

Improveprocess flexibilityVSAvoidindependent variable control

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent segments the multi-variable process control into independent variable ranges, where each variable is assigned its own permissible range that can be controlled independently. This is achieved by defining the feasible region as a hyper-rectangular space with axis-aligned boundaries, allowing operators to adjust each variable without complex interdependency calculations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent transforms the control approach by changing from dynamic interdependent ranges to static independent ranges. By using historical data to establish fixed permissible ranges for each variable, the system maintains operational simplicity while ensuring product quality through the convex hull containment guarantee.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If independent variable ranges are defined using historical data, then ease of operation is improved, but manufacturing precision and quality assurance may deteriorate

Engineering Contradiction:

Improveindependent variable controlVSAvoidproduct quality assurance

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent performs preliminary analysis of historical process data to establish the convex hull of the feasible region before defining independent variable ranges. This advance preparation ensures that the resulting independent ranges are mathematically guaranteed to keep the process within the feasible region, thereby maintaining product quality assurance while enabling independent variable control.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces complex dynamic control mechanisms with a geometric approach based on convex hull theory. By substituting the mechanical/algorithmic interdependency management with a geometric containment strategy, the system achieves both operational simplicity and quality assurance through mathematical guarantees.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If the feasible region is defined using the convex hull of historical data points, then manufacturing precision is improved, but device complexity and calculation complexity increase

Engineering Contradiction:

Improveproduct quality assuranceVSAvoidcontrol system complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent extracts the essential geometric property (convex hull) from the historical data without implementing the full complexity of dynamic optimization systems. By taking out only the necessary mathematical structure needed for quality assurance and discarding unnecessary computational complexity, the system achieves manufacturing precision with simplified control logic.

Inventive Principle:

Principle #2Taking out (Extraction)

4Manufacturing precision

If dynamic optimal control is derived from convex hull calculations, then manufacturing precision is improved, but loss of time in calculations and setup increases

Engineering Contradiction:

Improveproduct quality assuranceVSAvoidcalculation time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent performs the computationally intensive convex hull calculation and variable range determination as a preliminary step using historical data, rather than performing these calculations in real-time during process operation. This advance preparation eliminates repeated calculation time during manufacturing while maintaining quality assurance through the pre-established feasible region boundaries.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20250053608A1Method of operating a multi-variable process

Publication Date: 2025.02.13 CURVACEOUS SOFTWARE

AI summary

A method of operating a multi-variable process comprises deriving a multi-dimensional representation of the process variables according to individual co-ordinate axes, defining a feasible region of the process variables by selecting from an accumulation of historical sets of values of all the variables, obtained from multiple operations of the process, to define an operational envelope containing a set of data points for which the product qualities are within predetermined limits, calculating the convex hull of this set of data points, determining an interior hypercube inside the convex hull, the interior hypercube having sides that are parallel to each axis, and then operating the process with the process variables as defined within the interior hypercube.