Aircraft Nosewheel Heading Control Under Asymmetrical Thrust
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Solution Overview
Problem
Aircraft with shorter wheelbases are more sensitive to steering inputs, limiting the range of angles within which a heading control system can control the nosewheel without risking severe lateral movement, and are exacerbated by asymmetrical thrust during ground manoeuvres.
Innovation Solution
A heading control system that uses a computerized controller to provide proportional-integral-derivative (PID) control, adjusting the angle of the nose landing gear (NLG) to maintain aircraft heading, with adjustable gain terms to accommodate asymmetrical thrust and external influences like crosswinds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the nosewheel angle is controlled within a limited angular range to prevent severe lateral movement, then aircraft safety is improved, but the heading control authority is reduced
Solution Approach 1:
The patent applies dynamics by making the angular range limits adjustable rather than fixed. The control system dynamically adapts the maximum and minimum angular limits based on detected asymmetrical thrust conditions. When asymmetrical thrust is detected, the system increases the angular range limit in the direction opposing the thrust asymmetry, allowing greater heading control authority when needed while maintaining safety boundaries.
Solution Approach 2:
The patent changes the parameter of angular range limits based on operating conditions. By detecting asymmetrical thrust and adjusting the angular limits accordingly, the system modifies its control parameters to match the current flight state. This allows the heading control system to operate with expanded authority when asymmetrical thrust is present while maintaining restricted authority under normal conditions.
2Adaptability or versatility
If the angular range for nosewheel control is increased to improve heading control authority, then the ability to counteract asymmetrical thrust is improved, but the risk of severe lateral movement increases
Solution Approach 1:
The patent applies local quality by adjusting the angular range limits differently in different directional contexts. Rather than applying a uniform angular limit in all directions, the system detects the direction of asymmetrical thrust and selectively increases the angular range limit only in the direction needed to counteract that specific asymmetry. This localized adjustment provides targeted heading control authority while minimizing the overall risk of excessive lateral movement.
Solution Approach 2:
The system performs preliminary detection of asymmetrical thrust conditions and preemptively adjusts the angular range limits before severe lateral movement can occur. By detecting thrust asymmetry early and adjusting the control authority accordingly, the system prevents harmful lateral movements rather than reacting to them after they begin.
3Stability of the object's composition
If asymmetrical thrust compensation is enabled to improve heading stability, then the ability to maintain heading during ground manoeuvres is improved, but the complexity of the control system increases
Solution Approach 1:
The patent applies self-service by enabling the heading control system to automatically detect asymmetrical thrust conditions and adjust its own angular range limits without external intervention. The system monitors engine thrust parameters, detects asymmetries, and autonomously modifies its control boundaries, eliminating the need for additional manual systems or complex external control mechanisms.
Solution Approach 2:
The system uses feedback by continuously monitoring engine thrust parameters and using this information to adjust the angular range limits. The thrust detection mechanism provides feedback about asymmetrical conditions, and this feedback loop enables the control system to adaptively modify its operating parameters to maintain heading stability under varying thrust conditions.
Data Source
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AI summary
Disclosed is a heading control system for an aircraft. The heading control system is arranged to maintain a heading of an aircraft by controlling a nose wheel angle of the aircraft. The heading control system comprises an interface arranged to receive a bias signal indicating a bias towards the port or the starboard of the aircraft and one or more processors. The one or more processors are arranged to determine, based on the bias signal, an offset angle defining an offset from a longitudinal axis of the aircraft and to perform a control process to control the nose wheel angle within an angular range based on the offset angle.