Cooperative Precision PNT Across Networked Mobile Platforms
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Solution Overview
Problem
In contested environments, maintaining precise absolute and relative position, navigation, and timing (PNT) among mobile nodes, such as swarms of unmanned aircraft systems, is challenging in GPS-denied areas where satellite-based navigation is unreliable, and conventional solutions require expensive high-power anti-jamming receivers that are not justified by size, weight, and cost considerations.
Innovation Solution
A network of at least four mutually connected mobile nodes, with a key node equipped with an absolute position receiver, inertial measurement unit, and barometric altimeter, uses pseudoranging via two-way time transfer (TWIT) to generate and distribute precision relative PNT solutions, refining them with inertial state and pressure altitude data, and optionally incorporating additional sensors for enhanced accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional Link-16 RelNav functionality is used in GPS-denied environments, then relative navigation capability is provided, but the system requires multiple advantaged nodes with absolute positioning capacity to constrain the solution in six degrees of freedom, increasing system cost and complexity
Solution Approach 1:
The patent introduces a single advantaged node as an intermediary that provides absolute positioning references to the entire network. This node acts as a mediator between the GPS-denied environment and the relative navigation system, converting absolute PNT into relative PNT for distribution to all other nodes. This eliminates the need for multiple advantaged nodes while maintaining navigation accuracy.
Solution Approach 2:
The system creates a virtual copy of the absolute positioning capability through data processing. The single advantaged node's absolute PNT measurements are mathematically transformed into relative PNT solutions that are then distributed to all network nodes. This copying approach allows inexpensive nodes to access navigation accuracy equivalent to expensive absolute positioning receivers without physically possessing them.
2Reliability
If expensive high-power anti-jamming satellite-based receivers are installed on mobile nodes, then absolute positioning reliability in contested environments is improved, but size, weight, and cost increase significantly
Solution Approach 1:
The system enables self-service navigation where nodes without expensive anti-jamming receivers can still achieve reliable positioning by using the relative PNT solutions generated from the single advantaged node's absolute measurements. Each node in the network serves itself through distributed computation of relative positions based on shared data from the advantaged node and local inertial measurements.
Solution Approach 2:
The patent replaces expensive, complex anti-jamming satellite receivers with inexpensive alternative navigation approaches. Instead of investing in costly hardware on every node, the system uses low-cost inertial measurement units combined with computational methods to achieve the same navigation reliability, effectively substituting expensive objects with cheaper alternatives.
3Measurement precision
If multiple advantaged nodes with absolute positioning capacity are deployed, then six degrees of freedom constraint is achieved, but the SWaP-C (size, weight, power, and cost) burden increases for each node
Solution Approach 1:
The navigation function is segmented between different node types: a single advantaged node performs absolute positioning measurements and generates reference solutions, while other nodes perform relative positioning computations using distributed algorithms. This segmentation allows the computationally intensive absolute positioning function to be concentrated in one node, eliminating the need for expensive receivers on every node while maintaining overall network accuracy.
Solution Approach 2:
The system merges the absolute positioning capability of the advantaged node with the relative positioning computations of all network nodes. By combining absolute PNT references with distributed inertial measurements and relative ranging data, the system achieves six degrees of freedom navigation accuracy without requiring multiple expensive absolute positioning receivers, consolidating the heavy SWaP-C burden into a single node.
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 approach allows for the maintenance of relative precision PNT in six degrees of freedom over extended periods in GPS-denied environments, enabling expanded operational concepts and effective targeting of high-value targets without the need for expensive satellite-based receivers.
Implementation Method 1
a barometric altimeter for determining a pressure altitude of the node
Implementation Method 2
an inertial measurement unit (IMU) for determining an inertial state of the node (e.g., 6DoF) in an inertial reference frame
Implementation Method 3
a network radio for maintaining a data link to the other neighbor nodes of the network
Data Source
AI summary
A system and method established and maintains precision relative position, navigation, and timing (PNT) across a network of at least four mutually connected mobile platforms. In embodiments, a key (e.g., advantaged, absolute positioning capable) node of the network determines its pressure altitude and inertial state relative to its platform reference frame and receives inertial state and pressure altitude data from each neighboring node (in exchange for its own) to estimate the relative position and orientation of each neighbor node in its platform frame. The key node performs ranging to each neighboring node, and the neighboring nodes additionally range between each other and exchange ranging data with the key node. By correcting position and orientation estimates via ranging data, the key node determines and maintains extended relative PNT (e.g., in GPS-denied areas), which relative PNT solution is distributed across all network nodes.