Rotorcraft Airspeed Estimation via Tip Path Plane Angle
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Solution Overview
Problem
Existing rotary-wing aircraft systems rely on externally mounted sensors for airspeed measurement, which can fail due to mechanical defects or environmental conditions like ice accumulation, necessitating an alternative method to estimate airspeed within the fly-by-wire control system.
Innovation Solution
A method and system that estimate airspeed by calculating the tip path plane angle using operating conditions and referencing a lookup table to determine the airspeed, accommodating acceleration corrections, thereby providing an internal airspeed estimation within the fly-by-wire flight control system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If externally mounted sensors are used for airspeed measurement, then airspeed data can be obtained, but the system reliability deteriorates due to mechanical defects or environmental conditions such as ice accumulation
Solution Approach 1:
The patent creates a virtual copy of the airspeed measurement function by using the fly-by-wire system's existing sensors (accelerometers, gyroscopes, flight control inputs) to calculate and estimate airspeed through mathematical models, replacing the need for physical external airspeed sensors that are vulnerable to environmental damage
Solution Approach 2:
The fly-by-wire system performs self-diagnosis and self-measurement by using its own operational data (control inputs, attitude rates, acceleration measurements) to estimate airspeed, eliminating dependence on external sensors that can fail due to ice or mechanical issues
2Measurement precision
If external airspeed sensors are used, then airspeed measurement is achieved, but the device complexity increases due to additional external components
Solution Approach 1:
The patent makes the fly-by-wire system multi-functional by enabling it to perform both flight control and airspeed measurement functions using the same internal sensors and processing units, eliminating the need for separate external airspeed sensing equipment
Solution Approach 2:
The airspeed estimation function is merged with the existing fly-by-wire control system, combining multiple measurement capabilities (attitude, acceleration, control state) into a single integrated system that derives airspeed information without requiring additional external sensors
Data Source
AI summary
A method for estimating airspeed of an aircraft includes receiving values indicative of operating conditions of the aircraft along an axis; estimating a tip path plane (TPP) angle along the axis from at least one of the operating conditions to create an estimated TPP angle; and determining an estimated airspeed as a function of the estimated TPP angle, the determining including referencing a look-up table that indexes the estimated TPP angle with the airspeed.