Supervisory Model Predictive Control for Engine Torque and Fuel Optimization
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Solution Overview
Problem
Modern engines with multiple actuators face challenges in optimizing multiple objectives due to increasing complexity, as single-level optimization systems fail to distinguish between minimizing fuel consumption and delivering requested torque, leading to suboptimal performance in fuel economy, emissions, and drivability.
Innovation Solution
A multi-layered supervisory model predictive control system with an upper-level optimizer module and a lower-level tracking control module, utilizing decoupled cost functions to optimize system-level objectives like fuel consumption and torque delivery, while maintaining tracking parameters through actuator commands based on engine models and sensor data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-level optimization system is used to control multiple actuators, then the system structure is simple, but it fails to distinguish between minimizing fuel consumption and delivering requested torque, leading to suboptimal performance
Solution Approach 1:
The control system is segmented into two distinct levels: an upper-level optimizer that minimizes fuel consumption and a lower-level tracker that ensures torque delivery. This segmentation allows each level to focus on specific objectives without conflict, resolving the contradiction between system simplicity and optimization effectiveness.
Solution Approach 2:
The solution transitions from a single-level control architecture to a multi-layered hierarchical structure, adding a vertical dimension to the control system. This dimensional change enables simultaneous optimization of multiple conflicting objectives by distributing control functions across different hierarchical levels.
2Adaptability or versatility
If multiple actuators are added to achieve multiple goals, then fuel economy and other objectives can be improved, but the system complexity increases making optimization more challenging
Solution Approach 1:
The control system segments multiple actuators and control objectives into organized groups managed by different hierarchical levels. The upper level manages strategic optimization while the lower level handles tactical execution, making the complex multi-actuator system manageable and optimizable.
Solution Approach 2:
The hierarchical structure introduces intermediate control layers that mediate between the control module and multiple actuators. These intermediate layers process and coordinate control signals, reducing the complexity burden on any single component while enabling comprehensive multi-objective optimization.
3Device complexity
If the upper-level optimizer and lower-level tracker use the same cost function, then the control structure is unified, but they cannot independently optimize their respective objectives
Solution Approach 1:
The cost function is segmented into two distinct components: an upper-level cost function for fuel consumption optimization and a lower-level cost function for torque tracking. This segmentation allows each control level to independently optimize its specific objectives without interference from the other level.
Solution Approach 2:
Different cost functions are applied at different hierarchical levels according to their specific optimization needs. The upper level uses a fuel-economy-oriented cost function while the lower level uses a torque-tracking-oriented cost function, allowing each level to have the quality characteristics appropriate to its function.
Data Source
AI summary
An engine assembly includes a control module configured to receive a torque request and an engine configured to produce an output torque in response to the torque request. The control module includes a processor and tangible, non-transitory memory on which is recorded instructions for executing a method for supervisory model predictive control. The control module includes a multi-layered structure with an upper-level (“UL”) optimizer module configured to optimize at least one system-level objective and a lower-level (“LL”) tracking control module configured to maintain at least one tracking parameter. The multi-layered structure is characterized by a decoupled cost function such that the UL optimizer module minimizes an upper-level cost function (CFUL) and the LL tracking control module minimizes a lower-level cost function (CFLL). The system-level objective may include minimizing fuel consumption of the engine and the tracking parameter may include delivering the torque requested to engine.