Aircraft Lateral Path Control With Derivative Roll Segments
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Solution Overview
Problem
Current lateral path control laws in flight management systems (FMS) for aircraft result in non-zero cross track errors (XTK) during transitions between straight and curved path segments due to instantaneous roll response limitations, leading to buffers being placed around aircraft paths to prevent close proximity, which restricts parallel flight operations.
Innovation Solution
Incorporating derivative lateral path segments before and after straight-to-curve or curve-to-straight transitions, including constant roll rate and acceleration segments, to allow for a more natural and controlled roll attitude change, reducing XTK errors by using a controller to determine and apply derivative roll parameters for each segment of the lateral path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional lateral path control law is used, then aircraft can follow projected track, but cross track errors occur during transitions between straight and curved segments
Solution Approach 1:
The lateral path is divided into multiple segments: straight segments, constant roll attitude segments, and derivative segments (constant roll acceleration and constant roll rate). This segmentation allows the aircraft to transition smoothly between path types by breaking down the transition into controlled phases, eliminating abrupt changes that cause cross track errors.
Solution Approach 2:
The control system dynamically adjusts roll parameters by introducing derivative segments with constant roll acceleration and constant roll rate between straight and constant roll attitude segments. This dynamic transition approach replaces instantaneous roll changes with a controlled sequence of roll parameter changes, maintaining path accuracy during transitions.
2Reliability
If buffers are placed around projected aircraft track to prevent close proximity, then safety is maintained, but parallel flight operations are restricted
Solution Approach 1:
The patent replaces the mechanical approach of adding physical buffers around tracks with a control system approach. By using derivative segments to precisely control aircraft path following, the system achieves reliable parallel flight without requiring safety buffers, thus increasing parallel flight capacity while maintaining safety.
3Device complexity
If instantaneous roll response is assumed in control law, then control calculations are simplified, but cross track errors occur during path transitions
Solution Approach 1:
The control system performs preliminary actions by introducing derivative segments (constant roll acceleration and constant roll rate) before the aircraft reaches the constant roll attitude segment. This preliminary roll preparation ensures the aircraft is properly oriented before entering the turn, preventing cross track errors without significantly complicating the control law.
Data Source
AI summary
A method for controlling a desired change in course for an aircraft is provided. The method comprises: determining a roll angle for a constant radius curve in a constant roll attitude lateral path segment of a lateral path to achieve the desired change in course; determining, for each of a first plurality of derivative lateral path segments between a first straight lateral path segment of the lateral path and the constant roll attitude lateral path segment and a second plurality of derivative lateral path segments between the constant roll attitude lateral path segment and a second straight lateral path segment of the lateral path, a derivative roll parameter to apply in the lateral path segment, wherein the derivative roll parameter comprises a constant roll acceleration value or a constant roll rate value; and causing the aircraft to sequentially execute a maneuver specified by the roll angle and, derivative roll parameters.