Aircraft Landing Gear Wheel Angular Position Control
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Solution Overview
Problem
Existing systems for adjusting the angular position of an aircraft landing gear wheel experience oscillations and pressure variations due to periodic loading of the integral correction when the angular deviation is close to zero, leading to inefficient control and potential wear on the servo valve.
Innovation Solution
A method that limits the second current from the integral correction according to a parametric law, setting it to zero when the angular deviation is less than a predetermined threshold, thereby inhibiting the integral correction for small deviations and preventing untimely adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the integral correction is continuously applied to eliminate angular deviation, then the control precision is improved, but oscillations occur in the control current and pressure variations occur in the hydraulic cylinders
Solution Approach 1:
The patent changes the parameter of the integral correction current by introducing a limiting step that constrains its magnitude. When the angular deviation is small (close to zero), the integral correction current would normally continue to accumulate and increase, but the limiting step prevents it from exceeding a predetermined threshold value. This parameter constraint eliminates the oscillations in control current and pressure variations while maintaining acceptable control precision.
2Reliability
If a more efficient servo valve model is used to eliminate oscillations, then the control performance is improved, but the technical integration and certification complexity increases
Solution Approach 1:
Instead of replacing the entire servo valve system, the patent applies a localized modification only to the integral correction current signal. The limiting step is inserted specifically in the signal processing path of the integral correction, leaving the rest of the servo valve and hydraulic system unchanged. This localized approach improves control performance while avoiding the complexity of system-wide integration and recertification.
Solution Approach 2:
The patent creates a simplified version or copy of the integral correction function by limiting its output current to a maximum value. Rather than changing the physical servo valve, it creates a modified control signal that behaves like an improved valve would, achieving the desired performance improvement through software/control logic modification alone.
3Stability of the object's composition
If the integral correction is deactivated to limit oscillations, then the control current stability is improved, but the control performance and wear monitoring performance deteriorate
Solution Approach 1:
The patent applies partial action by selectively limiting the integral correction current only when it exceeds a certain threshold, rather than completely deactivating it or always limiting it to zero. When the angular deviation is large, the integral correction current is allowed to grow freely to ensure strong corrective action. Only when the deviation becomes small does the limiting engage, providing just enough correction to eliminate oscillations without over-correcting. This partial application maintains both stability and control performance.
Data Source
AI summary
A method for adjusting the angular position of a wheel, in particular a wheel of a landing gear on an aircraft. The wheel being connected to at least one hydraulic cylinder controlled by a servo valve. The method comprising a step for determining an angular deviation between a measurement of the angular position and a setpoint angular position, a first proportional correction step, a second integral correction step and a step for adding the first current and the second current in order to determine a control current of the servo valve. The second integral control step comprising a sub-step for limiting the second current according to a parametric law imposing a second current of zero value when the angular deviation is less, in absolute value, than a first determined threshold.