Aircraft Autopilot Control Using Sliding Mode and Feedback Linearization
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Solution Overview
Problem
Existing aircraft control systems face challenges in efficiently managing nonlinear dynamics across the entire operating envelope, requiring complex and costly parameter scheduling, and often fail to adapt to variations in flight conditions and aircraft configurations.
Innovation Solution
Implementing a combination of sliding mode control and feedback linearization techniques to compute target rates for bank, heading, and altitude control, using threshold-based functions and sigmoid mappings to adjust control inputs dynamically, thereby reducing the need for manual tuning and enhancing adaptability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If parameter scheduling is used to achieve desired performance across the entire operating envelope, then control performance is improved, but system complexity and cost increase
Solution Approach 1:
The patent transforms the control approach from scheduling multiple parameters across different operating conditions to using a single unified feedback linearization controller that adapts to varying flight conditions through real-time state feedback. This eliminates the need for complex parameter scheduling while maintaining control performance across the entire operating envelope.
Solution Approach 2:
The feedback linearization controller serves as a universal control solution that handles all flight conditions and configurations simultaneously, rather than requiring separate parameter schedules for different operating regimes. The controller universally manages nonlinear dynamics, coupling effects, and configuration transitions through a single control law.
2Device complexity
If linearization about a nominal operating point is used, then control system design is simplified, but adaptability to nonlinear dynamics and varying flight conditions deteriorates
Solution Approach 1:
The patent replaces the mechanical approach of linearizing aircraft dynamics about a nominal operating point with a mathematical transformation approach using feedback linearization. This substitution allows the controller to handle the full nonlinear dynamics exactly, rather than approximating them, while maintaining a relatively simple control structure through state-space transformation.
3Measurement precision
If manual tuning of control parameters is performed, then control precision can be optimized, but time and cost consumption increase
Solution Approach 1:
The feedback linearization controller is self-tuning in the sense that it automatically adapts to the aircraft's actual dynamics through real-time state feedback without requiring manual intervention. The control law inherently compensates for parameter variations and modeling uncertainties, eliminating the need for time-consuming manual tuning processes while maintaining optimal control precision.
Data Source
AI summary
Methods and systems for controlling a bank angle, a heading angle and an altitude of an aircraft during flight are provided. The methods and systems disclosed herein make use of sliding mode control and feedback linearization control (nonlinear dynamic control) techniques. The methods and systems can provide autopilot-type functions that can autonomously execute aggressive maneuvers as well as more gentle maneuvers for aircraft.