Aircraft Engine State-Feedback Decoupling for Multivariable Control
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Solution Overview
Problem
Conventional multivariable control systems for aircraft engines, such as turboprops and turbojets, face challenges in decoupling interactions between variables like power and propeller speed, leading to significant over-torques and operational inefficiencies, due to complex control laws and difficulty in adjusting settings during engine tests.
Innovation Solution
A decentralized control system with a state feedback decoupling approach, incorporating mono-variable regulators and static compensators, allows for total decoupling with simple state correctors and compensation matrices, enabling intuitive and adjustable control laws that maintain desired performance across various flight conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional multivariable control systems are used to control aircraft engine variables, then the system can handle multiple inputs and outputs, but the interactions between variables cause significant over-torques and operational inefficiencies
Solution Approach 1:
The patent divides the multivariable control system into multiple independent mono-variable control loops, each handling a specific variable (fuel flow, propeller pitch, nozzle section) separately. This segmentation eliminates the harmful interactions between variables that cause over-torques, while maintaining the ability to control all engine parameters through coordinated independent loops.
2Productivity
If complex control laws are used to coordinate variable geometries, then optimal performance can be achieved, but the control system becomes difficult to adjust and implement
Solution Approach 1:
The patent segments the complex multivariable control problem into simpler mono-variable control loops. Each loop uses basic proportional-integral-derivative (PID) control or similar simple control laws, avoiding the need for complex coordinated control algorithms. This maintains performance optimization through multiple controlled variables while dramatically reducing control law complexity and improving adjustability.
Solution Approach 2:
The patent introduces a coordinator unit that acts as an intermediary between the simple mono-variable control loops and the overall engine performance objectives. This coordinator manages the interactions between loops and adjusts setpoints to achieve optimal performance without requiring complex control laws in the individual loops.
3Reliability
If centralized multivariable control is used to coordinate all engine variables, then complete control coordination is achieved, but the system lacks ease of operation and adjustment during engine tests
Solution Approach 1:
The patent implements segmented independent control loops for each engine variable (fuel flow, propeller pitch, nozzle section), allowing operators to adjust each loop independently during engine tests without affecting other variables. This maintains reliable control coordination through the coordinator unit while providing ease of operation and rapid adjustability during testing and commissioning.
Data Source
AI summary
The proposed aircraft engine control system includes at least one servo-loop, and at least one state feedback control integrated into the servo-loop. The state feedback control includes a static compensator (M) and a state corrector loop (L) which are parametrized so as to decouple the states constituted by the operating parameters of the engine to be servo-controlled. The mono-variable regulators are then in turn parameterized so as to servo-control the operating parameters on the setpoints.