Engine Aftertreatment Optimization via Piecewise Linear Models
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Solution Overview
Problem
Current engine-aftertreatment systems face challenges in optimizing operations for real-world duty cycles while meeting stringent emissions regulations, minimizing fuel and reductant fluid consumption, and ensuring good drivability, due to the complexity of dynamic optimization techniques which are computationally expensive.
Innovation Solution
The implementation of a simplified optimization approach using piecewise linear response models and a quasi-simplex optimization process to determine optimal targets for manipulated variables, such as engine out nitrogen oxide (EONOx) and in-cylinder oxygen, allowing for real-time optimization of engine and aftertreatment system performance variables like reductant fluid and fuel consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex dynamic optimization techniques are applied to minimize fluid consumption and meet emissions regulations, then emissions compliance and fuel efficiency are improved, but computational cost and system complexity increase significantly
Solution Approach 1:
The patent segments the complex dynamic optimization problem into multiple simpler sub-problems by dividing the operating range into discrete regions and using piecewise linear response models for each region. This allows the system to apply simpler optimization techniques within each segment while maintaining overall optimization performance across the full operating range.
Solution Approach 2:
The patent changes the mathematical parameters of the optimization model by using piecewise linear relationships instead of complex non-linear dynamic models. This parameter transformation reduces computational complexity while preserving the essential optimization objectives of minimizing fluid consumption and meeting emissions constraints.
2Productivity
If complex dynamic optimization techniques are used to optimize engine operation, then performance optimization is improved, but real-time computational capability is compromised
Solution Approach 1:
By segmenting the operating space and using pre-computed piecewise linear response models, the system transforms complex real-time dynamic optimization into simpler look-up and interpolation operations that can be executed rapidly in real-time embedded controllers.
Solution Approach 2:
The patent performs preliminary computation offline to generate piecewise linear response models and optimization lookup tables. This preliminary action transfers computational burden from real-time operation to offline model generation, enabling fast real-time execution with minimal computational resources.
3Speed
If simplified optimization approaches are used to reduce computational burden, then real-time control capability is improved, but optimization accuracy may be reduced
Solution Approach 1:
The patent uses segmentation to create piecewise linear approximations that maintain high accuracy within each local region. By dividing the operating range into multiple segments, the system achieves both computational simplicity and optimization accuracy, as each segment can be modeled with simpler mathematics while collectively covering the full operating envelope.
Data Source
AI summary
Systems and methods for controlling a performance variable of an engine system are provided. An apparatus includes a response model circuit structured to apply a constraint to a response model that represents a relationship regarding a manipulated variable or a relationship between the performance variable and the manipulated variable. The apparatus further includes an optimization circuit structured to determine a target for the manipulated variable via the response model such that the target of the manipulated variable satisfies the constraint of the response model. The performance variable is indicative of performance of operation of the engine system and the manipulated variable is capable of affecting the performance variable. Operation of the engine system is adjusted based upon the target of the manipulated variable by controlling at least one of a fuel system or an air handling system of the engine system.