Aircraft Wheel Drive Steering Control at Low Speeds
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Solution Overview
Problem
Aircraft steering systems struggle to effectively control nose wheel steering, especially at low speeds or when stopped, particularly when an aircraft needs to maneuver autonomously on the ground without relying on main engines or external tow vehicles.
Innovation Solution
An engines-off wheel drive system interacts with the aircraft's nose wheel hydraulic steering system to augment or replace it, using differential thrust and wheel drive mechanisms to control steering, allowing autonomous ground movement and reducing loads on the steering system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If hydraulic steering system is used for nose wheel steering, then steering control is effective at normal taxi speeds, but steering control becomes ineffective at low speeds or when stopped
Solution Approach 1:
The patent combines the wheel drive system with the hydraulic steering system to create an integrated ground movement system. The wheel drive system provides propulsion and steering assistance at low speeds and when stopped, complementing the hydraulic steering system that operates effectively at normal taxi speeds. This merging resolves the contradiction by ensuring steering control effectiveness across the entire speed range.
Solution Approach 2:
The control system acts as an intermediary that automatically selects or blends between hydraulic steering control and wheel drive-based steering control based on aircraft speed. At low speeds and when stopped, the control system engages the wheel drive system to provide steering capability, while at normal taxi speeds, it transitions to hydraulic steering control, thus maintaining continuous effective steering control.
2Extent of automation
If wheel drive system is added for autonomous ground movement, then autonomous movement capability is achieved, but device complexity increases
Solution Approach 1:
The wheel drive system is designed to perform multiple functions: it provides propulsion for autonomous ground movement, assists with steering control at low speeds, and can replace engine-powered ground movement. By making the wheel drive system multi-functional, the patent achieves autonomous ground movement capability without proportionally increasing system complexity, as one subsystem serves multiple purposes.
Solution Approach 2:
The wheel drive system enables the aircraft to service its own ground movement needs without external assistance such as tow vehicles or engine power. The aircraft can autonomously move itself on the ground using the wheel drive system, reducing dependency on external systems and achieving self-service capability for ground operations.
3Speed
If hydraulic steering system operates at low speeds, then steering control is maintained, but forces on steering system components increase excessively
Solution Approach 1:
The system dynamically transitions between hydraulic steering control and wheel drive-based steering control based on operating conditions. At low speeds and when stopped, the wheel drive system provides the primary steering mechanism, reducing excessive forces on the hydraulic steering components. At normal taxi speeds, the system switches to hydraulic steering control, optimizing performance across different operating regimes and preventing overloading of components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables effective steering control at low speeds and when stopped, prolonging the life of the steering system by reducing forces on it and allowing autonomous aircraft movement without main engines or tow vehicles.
Implementation Method 1
using differential thrust and wheel drive mechanisms to control steering
Implementation Method 2
a hydraulic valve in the steering hydraulic system is commanded to send more or less pressure to a hydraulic actuating cylinder to move the nose wheels
Data Source
AI summary
Control of aircraft steering during ground travel is provided in an aircraft equipped with an engines-off wheel drive system controllable to move the aircraft autonomously on the ground without reliance on the aircraft's main engines or external tow vehicles. The wheel drive system is designed to interact with the aircraft's nose wheel hydraulic steering system to augment or replace the hydraulic steering system with the operation of the wheel drive system at taxi speeds, particularly at very low taxi speeds and even when the aircraft is stopped, to steer the aircraft as it maneuvers through turns during ground travel between landing and takeoff and at other times.