Autonomous Pushback Braking Torque Control
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Solution Overview
Problem
Conventional aircraft braking systems are unsuited for autonomous pushback operations, as they risk aircraft tip-over and runaway due to inadequate deceleration control during reverse motion on the ground, especially on slopes, without external tractor units.
Innovation Solution
An autonomous pushback braking system applies controlled torque to landing gear wheels using a wheel drive system and braking control, limiting torque to maintain longitudinal stability, with features like variable braking pressure, selective wheel braking, and energy dissipation through generators or resistors to manage speed and prevent tip-over and runaway.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional aircraft braking systems are used during autonomous pushback, then braking function is provided, but aircraft longitudinal stability is compromised leading to tip-over risk
Solution Approach 1:
The braking system dynamically adjusts brake torque based on real-time aircraft state parameters including speed, slope angle, and center of gravity position. The control system continuously modifies braking force to maintain longitudinal stability while achieving effective deceleration, preventing tip-over during autonomous pushback operations.
Solution Approach 2:
The system changes operational parameters by limiting brake torque to not exceed a calculated limit based on aircraft mass, center of gravity position, and slope angle. This parameter adjustment ensures that braking force remains within safe boundaries that prevent longitudinal instability while still providing necessary deceleration capability.
2Speed
If high braking torque is applied to decelerate the aircraft during pushback, then deceleration performance is improved, but aircraft tip-over risk increases
Solution Approach 1:
The system calculates and enforces a maximum brake torque limit based on aircraft parameters (mass, center of gravity) and operational conditions (slope angle, speed). This parameter change ensures deceleration remains effective while preventing torque levels that would cause longitudinal instability and tip-over.
Solution Approach 2:
The control system continuously monitors aircraft speed, slope angle, and other state parameters, using this feedback to dynamically adjust brake torque application. This closed-loop control ensures deceleration performance is optimized while maintaining longitudinal stability by preventing excessive torque that would cause tip-over.
3Adaptability or versatility
If autonomous pushback is performed on a slope, then operational flexibility is improved, but runaway risk increases due to gravity acceleration
Solution Approach 1:
The system calculates a slope-specific torque limit that accounts for the gravitational component acting on the aircraft. By adjusting the maximum allowable brake torque based on slope angle, the system maintains control authority to prevent runaway while enabling operation on inclined surfaces, thus preserving operational flexibility without compromising safety.
Solution Approach 2:
The control system proactively compensates for gravitational acceleration on slopes by pre-calculating and applying appropriate brake torque limits before runaway can occur. This preliminary anti-action counteracts the destabilizing effect of gravity on inclined surfaces, preventing runaway while maintaining operational capability on slopes.
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
Ensures safe and controlled deceleration during autonomous pushback maneuvers, preventing tip-over and runaway by maintaining aircraft stability and allowing for efficient energy dissipation, thus enhancing operational safety and flexibility.
Implementation Method 1
applying a torque to at least one landing gear wheel of the aircraft, the torque being in a direction opposite to the backwards rolling direction of rotation of the landing gear wheel
Implementation Method 2
a means for applying a torque to at least one landing gear wheel of the aircraft, the torque being in a direction opposite to the backwards rolling direction of rotation of the landing gear wheel
Implementation Method 3
energy dissipation through generators or resistors to manage speed
Data Source
AI summary
The invention provides methods and systems for controlling speed of an aircraft during an autonomous pushback manoeuvre, i.e. under the aircraft's own power without a pushback tractor. The method includes applying a torque to at least one landing gear wheel of the aircraft, the torque being in a direction opposite to the backwards rolling direction of rotation of the landing gear wheel. The torque applied does not exceed a limit for ensuring aircraft longitudinal stability. For longitudinal stability the torque applied should not cause the aircraft to risk a tip-over event.