Rotorcraft Flight Control Using Complementary Airspeed Estimation
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Solution Overview
Problem
Rotorcrafts face challenges in accurately determining airspeed, especially at varying speeds, due to differences in flight characteristics between hovering and cruising, which complicates flight control and increases pilot workload, as existing systems struggle to decouple tightly coupled flight parameters effectively.
Innovation Solution
A method and system that utilize a combination of sensor signals from a pitot tube and an accelerometer, employing complementary filtering to estimate airspeed values, adjusting flight control devices based on these estimates, and resetting the filter according to predetermined speed thresholds to improve accuracy and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If raw airspeed values from a pitot tube are used directly for flight control, then the system is simple and responsive, but airspeed determination accuracy deteriorates at varying speeds especially during hover-to-cruise transitions
Solution Approach 1:
The patent combines multiple sensor signals (pitot tube airspeed, accelerometer acceleration, GPS groundspeed) through complementary filtering to produce a unified airspeed estimate. This merging of independent measurement sources resolves the contradiction by improving accuracy through data fusion while keeping each individual sensor simple and reliable.
Solution Approach 2:
The complementary filter acts as an intermediary that processes and combines raw sensor data from multiple sources. It mediates between the pitot tube's direct airspeed measurement and the accelerometer's acceleration data, producing a smoothed, accurate airspeed estimate that resolves the contradiction between simplicity and precision.
2Measurement precision
If complementary filtering is applied to estimate airspeed values, then airspeed estimation accuracy improves, but computational complexity and processing time increase
Solution Approach 1:
The patent replaces complex mechanical airspeed measurement systems with a computational approach using complementary filtering of electronic sensor data. This substitution allows for real-time processing of multiple sensor inputs through algorithmic filtering rather than complex mechanical mechanisms, improving accuracy while maintaining real-time performance.
3Ease of operation
If flight control parameters are tightly coupled as in traditional rotorcraft systems, then the system is stable and predictable, but pilot workload increases and control intuitiveness decreases in complex flight regimes
Solution Approach 1:
The patent segments the tightly coupled flight control parameters into independent control channels by using the accurate airspeed estimate from complementary filtering. This allows the flight control system to decouple speed control from attitude control, reducing pilot workload and improving control intuitiveness while maintaining overall system stability through coordinated control laws.
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
Enhances airspeed estimation accuracy and flight control stability by effectively decoupling flight parameters, reducing pilot workload, and maintaining intuitive control, even in complex flight regimes.
Implementation Method 1
combining the first sensor signal and the second sensor signal with a complementary filter to determine estimated airspeed values
Implementation Method 2
integrating the second sensor signal with respect to time to obtain a first filtered signal
Implementation Method 3
receiving a first sensor signal from a first aircraft sensor of a rotorcraft, the first sensor signal including raw airspeed values of the rotorcraft; In some embodiments of the method, the first aircraft sensor is a pitot tube
Implementation Method 4
receiving a second sensor signal from a second aircraft sensor of the rotorcraft... In some embodiments of the method, the second aircraft sensor is an accelerometer
Data Source
AI summary
In an embodiment, a rotorcraft includes: a flight control computer configured to: receive a first sensor signal from a first aircraft sensor of the rotorcraft; receive a second sensor signal from a second aircraft sensor of the rotorcraft, the second aircraft sensor being different from the first aircraft sensor; combine the first sensor signal and the second sensor signal with a complementary filter to determine an estimated vertical speed of the rotorcraft; adjust flight control devices of the rotorcraft according to the estimated vertical speed of the rotorcraft, thereby changing flight characteristics of the rotorcraft; and reset the complementary filter in response to detecting the rotorcraft is grounded.