UAV Flight Control Using Commanded Speed After Airspeed Sensor Failure
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Solution Overview
Problem
Aerial vehicles, such as UAVs, face challenges in maintaining accurate flight control when airspeed sensors fail or become misaligned with the flight vector, leading to unreliable airspeed measurements and loss of control authority.
Innovation Solution
The system contingently uses a 'commanded speed' instead of sensed airspeed to inform flight control decisions, ensuring appropriate thrust and torque allocations even when airspeed measurements are unreliable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sensed airspeed is used to inform flight control decisions, then accurate flight control can be maintained under normal conditions, but control authority is lost when airspeed sensors fail or become misaligned
Solution Approach 1:
The system pre-calculates and stores thrust and torque allocation mappings for various commanded speeds before flight. When airspeed sensing becomes unreliable, the control system can immediately switch to using pre-computed allocations based on commanded speed from the navigation system, avoiding the need for real-time sensor data and complex recalculation during critical failure conditions.
Solution Approach 2:
The patent introduces commanded speed as an intermediary parameter that bridges the navigation system and flight control system. Instead of directly using sensed airspeed (which may be unreliable), the system uses commanded speed from navigation as a mediator to determine appropriate thrust and torque allocations, ensuring continuous control authority even when airspeed sensors fail or become misaligned.
2Measurement precision
If airspeed sensor is used for flight control, then accurate speed measurement is obtained during aligned flight, but measurement reliability deteriorates when vehicle is misaligned with flight vector
Solution Approach 1:
Instead of relying on the airspeed sensor to provide accurate measurements during misaligned flight (the traditional approach), the system inverts the logic by using the commanded speed from the navigation system as the primary reference. This inversion allows the control system to maintain accuracy regardless of vehicle orientation relative to the flight vector, as commanded speed is derived from navigation data rather than sensor measurements that are sensitive to misalignment.
3Reliability
If commanded speed is used instead of sensed airspeed, then control authority is maintained during sensor failure, but additional computational logic is required
Solution Approach 1:
The system pre-calculates and stores thrust and torque allocation mappings for various commanded speeds before flight operations begin. This preliminary computation eliminates the need for complex real-time calculations when switching to commanded speed-based control during failures, as the allocations are already computed and ready for immediate use, thereby reducing the actual runtime computational complexity despite adding pre-flight preparation steps.
Data Source
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AI summary
A technique for controlling an unmanned aerial vehicle (UAV) includes monitoring a sensed airspeed of the UAV, obtaining a commanded speed for the UAV, wherein the commanded speed representing a command to fly the UAV at a given speed relative to an airmass or to Earth, and when the commanded speed is greater than the sensed airspeed, using the commanded speed in lieu of the sensed airspeed to inform flight control decisions of the UAV.