Aircraft Undercarriage Steering Control Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The use of deterministic fieldbuses with slow sampling intervals leads to instability in steering control of aircraft undercarriages equipped with electromechanical steering actuators, particularly due to slow speed information communication.
Innovation Solution
Implementing an H∞ type control relationship with prefiltering of the angular position setpoint using a discrete interpolator, allowing stable servo-control over a deterministic fieldbus while maintaining a remote computer and internal speed feedback loop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If deterministic fieldbus is used for communication, then device complexity is reduced and remote control is enabled, but control stability deteriorates due to slow sampling intervals
Solution Approach 1:
The patent changes the control parameters by implementing an H∞ controller with specific weighting functions that account for the slow sampling rate of the deterministic fieldbus. The controller parameters are optimized to maintain stability despite the reduced communication frequency, allowing the system to achieve stable servo-control with remote implementation.
Solution Approach 2:
The patent introduces an intermediary prefilter that processes the position setpoint before it reaches the H∞ controller. This prefilter smooths the reference signal and compensates for the delays introduced by the deterministic fieldbus, acting as a mediator between the slow communication bus and the control algorithm to maintain stability.
2Ease of manufacture
If computer is placed remote from actuator, then independence of development is improved, but control performance deteriorates due to communication delays
Solution Approach 1:
The patent implements a robust feedback mechanism using H∞ control theory that explicitly accounts for the communication delays between the remote computer and the actuator. The controller uses feedback from position and speed sensors to continuously adjust the control output, compensating for the delays introduced by the deterministic fieldbus and maintaining reliable control response.
Solution Approach 2:
The patent applies preliminary filtering to the position setpoint signal before it is processed by the controller. This prefiltering action anticipates the delays and disturbances caused by remote communication, shaping the reference signal in advance to ensure that the control system can track the desired trajectory reliably despite the communication latency.
3Device complexity
If PID controller is used with deterministic bus, then implementation simplicity is improved, but control precision deteriorates due to instability
Solution Approach 1:
The patent replaces the conventional PID controller with an H∞ controller that has parameters specifically designed for robust performance with slow sampling rates. The H∞ controller uses a different mathematical framework that is less sensitive to the timing variations and delays introduced by the deterministic fieldbus, thereby maintaining position control precision where PID would fail.
Solution Approach 2:
The patent introduces a prefilter as an intermediary element that processes the position setpoint before it reaches the H∞ controller. This prefilter smooths high-frequency components and anticipates the effects of slow sampling, acting as a mediator that enables precise position control to be achieved despite the limitations of the deterministic bus communication.
Data Source
AI summary
The invention relates to a method of managing a steering control for a steerable portion of an aircraft undercarriage, the method comprising implementing servo-control to servo-control an electromechanical steering actuator on an angular position setpoint, wherein, according to the invention, the servo-control implements a control relationship H∞ type, the position and speed information being delivered by means of a fieldbus of deterministic type to a computer that implements the servo-control.