Dual Corrector Valve Control for Asymmetric Servo Response
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Solution Overview
Problem
Conventional servo-control solutions for three-way valves in aircraft turbomachines, such as open rotor engines, fail to meet specifications due to functional dissymmetry, resulting in inaccurate temperature regulation and instability, as the valve's response time and behavior differ significantly between positive and negative control variations.
Innovation Solution
A control method using two different correctors with distinct parameters is applied based on the operating direction of the valve, one being fast for slow reactions and vice versa, to compensate for the dissymmetric behavior, along with a hysteresis parameter to manage oscillations and an incrementer to smooth transitions, ensuring stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single corrector is used for valve control, then the control structure is simple, but the temperature regulation accuracy deteriorates due to dissymmetric valve behavior
Solution Approach 1:
The control system is segmented into two distinct correctors (first corrector for positive control variations, second corrector for negative control variations) that operate independently based on the direction of valve movement. This segmentation allows each corrector to be optimized for its specific operating direction, resolving the contradiction between structural simplicity and regulation accuracy.
Solution Approach 2:
The control system dynamically switches between two different correctors based on the operating direction of the valve. The calculator automatically selects which corrector to apply depending on whether the control variation is positive or negative, making the control structure adaptive rather than static. This dynamic approach maintains simplicity while achieving high accuracy.
2Speed
If a fast corrector is used for slow valve reactions, then the response time is improved, but instability occurs due to excessive control action on fast reactions
Solution Approach 1:
Each corrector is designed with local quality tailored to its specific operating direction. The first corrector has parameters optimized for positive control variations, while the second corrector has parameters optimized for negative control variations. This local optimization ensures that each corrector provides the appropriate level of control action for its specific context, achieving both fast response and stability.
Solution Approach 2:
The system changes control parameters by switching between two different correctors with distinct parameter sets. Instead of using a single set of parameters that must compromise between fast and slow responses, the system selects the appropriate parameter set based on the operating direction, thereby achieving optimal response time and stability for each direction.
3Device complexity
If conventional linear check strategies are used, then the control method is simple, but the regulation accuracy deteriorates due to non-linear valve behavior
Solution Approach 1:
The invention explicitly embraces the asymmetric nature of the valve's non-linear behavior by implementing two different correctors with different parameters. Rather than attempting to force a symmetric linear control approach on an asymmetric non-linear system, the solution designs the control structure to match the valve's inherent asymmetry, thereby achieving high regulation accuracy while maintaining relative simplicity.
4Device complexity
If a single corrector with compromised parameters is used, then the control structure is simple, but both response time and overflow specifications cannot be met simultaneously
Solution Approach 1:
The control system achieves multi-functionality by implementing two correctors that together can satisfy both response time and overflow specifications. The first corrector handles positive control variations with parameters optimized for one set of specifications, while the second corrector handles negative control variations with parameters optimized for the other set of specifications. This universal approach allows the system to meet all demanding specifications across the entire operating range.
Data Source
AI summary
The invention concerns a method for controlling a mechanism (10) displaying asymmetrical behaviour, the mechanism (10) comprising a first operating direction (F+) and a second operating direction (F−), the control method making it possible to generate, using a control module (24) of a computer (20), a control signal (x_com) from a setpoint signal (x_cons), in which—when the setpoint signal (x_cons) indicates that the mechanism (10) should be operated in the first direction (F+), the control module (24) applies a first corrector (100) to the setpoint signal (x_cons) in order to generate a control signal (x_com),—when the setpoint signal (x_cons) indicates that the mechanism (10) should be operated in the second direction (F−), the control module (24) applies a second corrector (100) to the setpoint signal (x_cons) in order to generate a control signal (x_com), and in which the first and second correctors (100, 200) have different parameters (Kp1, Kp2, Ti1, Ti2), in order to compensate for the asymmetrical behaviour of the mechanism (10).