Aircraft Camera Rangefinder for Precision AGL Altitude Control
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Solution Overview
Problem
Conventional aircraft guidance and control systems face challenges in accurately determining altitude above ground level (AGL) when operating close to the ground, especially with external cargo loads, and in providing precise control mechanisms for unmanned helicopters, particularly near moving platforms like ships, due to interference with direct line-of-sight sensors and reliance on inaccurate altitude sources.
Innovation Solution
An aircraft command and control system equipped with a camera having a range finder, navigation system, and a computer to measure and compute the position of a fixed point on the aircraft relative to a target on the ground, allowing for precise control of azimuth, elevation, and slant range, supported by gimbals for angular measurements, and a controller to maintain the aircraft's position, which includes an automatic tracking mechanism for moving objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional AGL altitude sensors are used to measure height above ground, then accurate altitude measurement is achieved, but the cargo load obscures the sensor's view of the ground causing the sensor to indicate height above the load rather than height above the ground
Solution Approach 1:
The patent introduces an intermediary computational process that takes multiple sensor inputs (barometric pressure, GPS altitude, terrain database data, and radar altimeter readings) and combines them through algorithms to calculate the true AGL altitude. This computational intermediary resolves the contradiction by bypassing the direct line-of-sight requirement while maintaining measurement accuracy.
Solution Approach 2:
The system employs multiple altitude measurement systems serving different functions: barometric sensors for general altitude trends, GPS for horizontal positioning, terrain databases for reference elevation, and radar altimeters for precise vertical distance when available. This multi-functional approach ensures accurate AGL measurement regardless of cargo load interference with any single sensor.
2Adaptability or versatility
If Barometric Altitude or GPS altitude with terrain database is used to provide AGL altitude estimates, then a solution to cargo interference is provided, but the error margins are sufficiently large that they cannot be relied upon for near-Earth operations
Solution Approach 1:
The patent merges multiple independent altitude measurement systems into a unified AGL calculation. By combining barometric pressure data, GPS altitude, terrain database reference elevations, and radar altimeter readings, the system achieves precision suitable for near-Earth operations. The fusion of these diverse data sources compensates for the limitations of any single system.
Solution Approach 2:
The system implements feedback mechanisms where the control system continuously monitors AGL altitude from multiple sources and adjusts the helicopter's flight path accordingly. This closed-loop control ensures that even with varying error margins from different sensors, the aircraft maintains precise control during low-altitude operations.
3Measurement precision
If a radar altimeter is used as the primary source of AGL altitude for low altitude operations, then precise altitude control is achieved, but the loss of this sensor becomes very critical with respect to the aircraft's flight operations
Solution Approach 1:
The patent applies different quality levels of altitude measurement to different operational contexts. When the radar altimeter is functional and has a clear view, it provides high-precision local measurements. When obscured or failed, the system transitions to using the fused data from barometric, GPS, and terrain database sources. This localized adaptation of measurement quality maintains reliability while preserving precision when available.
Solution Approach 2:
The system prepares for radar altimeter failure by having pre-integrated alternative altitude sources ready to immediately take over. The barometric, GPS, and terrain database systems are continuously processed and stand by to provide AGL altitude calculations if the radar altimeter becomes unavailable, cushioning against the critical impact of sensor loss.
4Measurement precision
If conventional AGL altitude sensors are positioned on the aircraft, then direct measurement is possible, but it is difficult to locate sensors such that external loads will not interfere under all conditions
Solution Approach 1:
The patent replaces the mechanical approach of physically positioning sensors to avoid cargo interference with a computational solution. Instead of relying on sensor placement geometry, the system uses software algorithms to fuse data from multiple sensor types, eliminating the need for complex mechanical sensor positioning arrangements and providing adaptability to various cargo configurations.
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
This system provides enhanced control of helicopters, especially unmanned ones, in low-speed environments and enables precise landings and cargo operations on both fixed and moving platforms, offering a simpler and more cost-effective solution compared to prior art by providing redundant and accurate AGL altitude measurements.
Implementation Method 1
a camera, including a range finder, disposed aboard an aircraft for measuring an azimuth angle, an elevation angle and a slant range from a fixed point on the aircraft relative to a selected target point on a surface located below the aircraft
Implementation Method 2
the camera is supported on gimbals, and wherein the gimbals are used to measure the azimuth and elevation angles to the target point
Data Source
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AI summary
An aircraft control system for operations close to the ground includes a camera having a rangefinder for measuring the azimuth, elevation and slant range from a fixed point on the air-craft relative to a selected target point on a surface below the aircraft, a navigation system for measuring the latitude and longitude of the aircraft on the surface, a computer for computing the position of the fixed point on the aircraft relative to the target point from the respective meas-urements of the camera and the navigation system, and a controller for controlling the movement of the aircraft such that the fixed point is positioned at a selected position above the selected tar-get point on the surface. The controller may also include an automatic tracking mechanism for maintaining the position of the fixed point on the aircraft at the selected position above a moving object.