GPS Altitude Hold Switching for Stable Aircraft Altitude Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing aircraft altitude control systems, such as radar and barometric altimeters, are susceptible to interference and fluctuations due to environmental conditions, leading to inconsistent altitude maintenance, especially over dynamic terrain or high altitudes.
Innovation Solution
Implementing a GPS altitude hold mode using an Embedded GPS-aided inertial navigation system (EGINS) for consistent altitude control based on mean sea level readings, which is independent of terrain and atmospheric conditions, allowing for manual or automated mode selection and integration with digital terrain data for improved situational awareness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If radar altitude hold mode is used to maintain fixed height above surface, then obstacle avoidance capability is improved, but altitude control stability deteriorates due to terrain fluctuations and wave interference
Solution Approach 1:
The system segments altitude measurement into two independent components: vertical position from GPS and terrain height from DTED database, each processed separately to eliminate their individual weaknesses and combined to provide stable altitude control
Solution Approach 2:
The patent introduces digital terrain and elevation data (DTED) as an intermediary layer between the GPS altitude reading and the terrain surface, allowing the system to calculate height above terrain without direct radar measurement, thereby eliminating wave and terrain fluctuation interference
2Ease of operation
If barometric altitude hold mode is used to maintain fixed altitude, then navigation capability is improved, but measurement precision deteriorates due to atmospheric pressure fluctuations and rotor wake
Solution Approach 1:
The patent replaces the barometric pressure-based measurement system with a GPS-based satellite positioning system, substituting atmospheric pressure sensing with electromagnetic signal-based altitude determination, thereby eliminating sensitivity to atmospheric conditions and rotor wake effects
3Loss of information
If radar altimeter is used for altitude measurement, then above ground level reading is improved, but reliability deteriorates at high altitude due to beam return limitations
Solution Approach 1:
The patent makes the GPS altitude system universal by enabling it to provide accurate altitude information across all altitude ranges, from low-altitude obstacle avoidance to high-altitude navigation, replacing the altitude-limited radar altimeter with a globally applicable satellite-based system
Data Source
AI summary
Systems and methods for controlling an aircraft to hold altitude using GPS altitude readings. One example system includes a GPS inertial navigation system, an altimeter, a human machine interface, and one or more electronic processors coupled to the GPS inertial navigation system, the altimeter, and the human machine interface. The one or more electronic processors configured to receive, from the human machine interface, a user input selecting a reference altitude. The one or more electronic processors configured to receive, from the altimeter, a current altitude for the aircraft. The one or more electronic processors configured to: when the current altitude does not exceed an altitude threshold, operate the aircraft in an altimeter altitude hold mode based on the reference altitude; and when the current altitude exceeds the altitude threshold, operate the aircraft in a GPS altitude hold mode based on the reference altitude using the GPS inertial navigation system.