Attitude Hold Control for Fine Aircraft Refueling Tracking
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Solution Overview
Problem
Large aircraft face challenges in achieving precise control during in-flight refueling using the Probe and Drogue system, requiring pilots to maintain exact heading and altitude alignment with the tanker, which is difficult due to the system's high precision demands and complex pilot inputs, especially for less maneuverable aircraft.
Innovation Solution
A fly-by-wire control system with a dedicated Attitude Hold Button and modified Attitude Command Attitude Hold system, incorporating roll and pitch attitude stability loops, a Command Shaping function, and Fine Tracking Quickener, allows pilots to capture and maintain reference attitudes more easily, reducing pilot workload and improving tracking accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the Probe and Drogue system is used for in-flight refueling, then the system complexity and cost are reduced, but the pilot workload and control precision requirements increase significantly
Solution Approach 1:
The patent introduces an Attitude Hold Button as an intermediary device between the pilot and the complex attitude control system. When pressed, this button automatically captures and holds the reference bank angle and pitch attitude, serving as a mediator that simplifies the pilot's interaction with the multi-parameter control system while maintaining the required precision for drogue tracking.
Solution Approach 2:
The system performs preliminary action by automatically capturing and storing reference attitude values (bank angle and pitch attitude) before the pilot needs them. The Attitude Hold Button pre-establishes these reference values, so when the pilot needs to perform fine tracking maneuvers, the reference attitudes are already prepared and ready to be applied, reducing the pilot's real-time computational burden.
2Ease of operation
If manual attitude control is used during fine tracking, then the aircraft can respond to pilot inputs, but the precision and stability of attitude maintenance deteriorate due to pilot workload
Solution Approach 1:
The patent implements feedback by continuously comparing the actual aircraft attitudes (bank angle and pitch attitude) with the reference attitudes captured by the Attitude Hold Button. The control system uses this feedback to automatically adjust and maintain the attitude differences, ensuring that the aircraft stays precisely aligned with the reference trajectory even when pilot inputs are simplified or delayed.
3Productivity
If the pilot manually maintains reference attitudes during side step maneuvers, then the aircraft can perform lateral corrections, but the time and precision required increase due to the need to return to original attitudes
Solution Approach 1:
Before the pilot initiates a side step maneuver, the Attitude Hold Button has already captured and stored the reference bank angle and pitch attitude. During the maneuver, when the pilot releases the button, the system automatically recalls these pre-stored reference values and maintains them throughout the maneuver, eliminating the need for the pilot to manually remember or calculate the original attitudes and enabling faster, more precise maneuver execution.
Data Source
Figure 1-1~1-3
Figure 1-4
Figure 1a
AI summary
To improve high gain tracking characteristics of an aircraft during inflight probe and drogue refueling and other tasks requiring rapid trim capturing, an attitude hold button on the inceptor controls capture of current aircraft attitude and uses this attitude to update reference attitude datum. The pilot has the option of adjusting the attitude reference using an additional control such as a standard trim hat button.