Pseudolite Landing Navigation for Precise eVTOL Vertical Approach
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Solution Overview
Problem
Current aircraft navigation systems, such as those used in eVTOL aircraft, lack the precision, integrity, and availability required for vertical take-off and landing in dense urban areas, particularly in terms of horizontal and vertical position accuracy and failure probability.
Innovation Solution
A navigation, take-off, and landing support system (NTLS) that utilizes a plurality of pseudolites distributed around the landing area, a monitoring receiver, and a control system to transmit and receive RF signals, allowing the aerial vehicle to determine its position and velocity relative to the pseudolites and ensuring that only pseudolites operating within a nominal range are used for navigation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current aircraft navigation systems are used, then the system is simple and easy to operate, but the position accuracy and reliability are insufficient for vertical landing in dense urban areas
Solution Approach 1:
The navigation system is segmented into multiple independent pseudolite transmitters distributed around the landing area, each providing localized positioning signals. This segmentation allows the aerial vehicle to receive signals from multiple sources and calculate position through triangulation, significantly improving measurement precision while distributing system complexity across multiple simple units rather than one complex system
Solution Approach 2:
Pseudolites serve as intermediary devices between the landing area infrastructure and the aerial vehicle's navigation system. These intermediaries transmit RF signals that enable precise position and velocity determination without requiring the aerial vehicle to carry complex external navigation equipment, thus improving accuracy while keeping the vehicle system relatively simple
2Reliability
If multiple pseudolites are deployed to improve navigation reliability, then the position accuracy and failure probability improve, but the system complexity and infrastructure requirements increase
Solution Approach 1:
The system implements local quality by deploying pseudolites specifically around the landing area rather than relying on global satellite navigation. Each pseudolite is positioned to provide optimal signal coverage for its local zone, creating a concentrated network that achieves high reliability for the specific function of vertical landing without the need for extensive global infrastructure
Solution Approach 2:
The monitoring receiver and control system are configured to detect pseudolite failures beforehand and switch to alternative pseudolites or signal sources before actual navigation failure occurs. This prior cushioning approach ensures that even if some pseudolites fail, the navigation system maintains reliability by having pre-established backup capabilities
3Measurement precision
If pseudolites are used to achieve precise vertical landing, then position and velocity determination accuracy improves, but the requirement for monitoring and control infrastructure increases
Solution Approach 1:
The monitoring receiver serves multiple functions: it monitors pseudolite signal quality, measures code and carrier phases for position calculation, detects clock bias, and provides feedback to the control system. This multi-functionality reduces the need for separate dedicated monitoring equipment, achieving high velocity measurement precision without proportionally increasing infrastructure complexity
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
The NTLS achieves the required precision and reliability for vertical landing in dense urban environments by providing accurate position and velocity data to the aerial vehicle, while ensuring the integrity of the navigation system through redundant pseudolites and monitoring receivers.
Implementation Method 1
Each pseudolite is configured to transmit a radio frequency (RF) signal that facilitates determining, by the aerial vehicle and based on a code phase and a carrier phase of the RF signal, its position and velocity relative to the pseudolite
Implementation Method 2
The monitoring receiver is positioned proximate the landing area and is configured to receive RF signals from the plurality of pseudolites, measure the code phase and the carrier phase associated with each of the plurality of pseudolites, and determine corresponding clock bias estimates
Data Source
AI summary
A navigation, take-off, and landing support system (NTLS) that facilitates vertical landing at a landing area by an aerial vehicle comprises a plurality of pseudolites distributed proximate the landing area. Each pseudolite is configured to transmit a radio frequency (RF) signal that facilitates determining, by the aerial vehicle, its position and velocity relative to the pseudolite and whether the pseudolite is operating within a nominal operating range. A monitoring receiver is positioned proximate the landing area and is configured to receive RF signals from the pseudolites. A control system is in communication with the pseudolites and the monitoring receiver. The control system is configured to determine, based on the RF signals received from the monitoring receiver, whether the pseudolites are operating within a nominal operating range and to indicate to each of the pseudolites whether the pseudolite is operating within a nominal operating range.