Self-Correcting Adaptive Tracking System for GPS-Denied Navigation
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Solution Overview
Problem
GPS signals are often unavailable or intermittently observable in military and emergency rescue scenarios, making traditional GPS-only tracking systems ineffective for group location and navigation, and existing alternatives like IMU and RF/ultrasonic devices suffer from substantial errors and lack directional information.
Innovation Solution
The Self-correcting Adaptive Tracking System (SATS) uses Ultra-Wide Band ranging among group members, Inertial Measurement System, and WLAN for exchanging information, with a leader node determining relay placement and an adaptive orientation-correcting polygon matching process to stabilize group orientation and provide accurate navigation in GPS-denied environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GPS-only tracking system is used, then the system is simple and reliable when GPS is available, but it becomes unusable when GPS signals are unavailable
Solution Approach 1:
The patent combines GPS with alternative tracking methods (inertial navigation, RF/ultrasonic ranging) into a hybrid system. When GPS is available, it provides global positioning; when GPS is denied, the system seamlessly transitions to using inertial measurement units and relative positioning techniques, ensuring continuous tracking capability across all environments.
Solution Approach 2:
The system dynamically adapts its operation mode based on GPS signal availability. It continuously monitors GPS signal quality and automatically switches between GPS-based tracking and alternative methods (inertial navigation, peer-to-peer ranging), making the system versatile across different operational conditions.
2Adaptability or versatility
If Inertial Measurement Units (IMU) are used for tracking, then the system can operate without GPS, but substantial errors occur due to bias in accelerometer and gyroscope
Solution Approach 1:
The system uses feedback mechanisms where each node continuously measures its position relative to other nodes using RF or ultrasonic ranging. These relative position measurements serve as feedback to correct drift accumulation in inertial navigation, maintaining long-term accuracy without GPS by constantly reconciling inertial predictions with actual measured distances.
Solution Approach 2:
The patent introduces peer-to-peer ranging measurements as an intermediary between inertial navigation and absolute positioning. Instead of relying solely on inertial sensors that drift over time, the system uses distance measurements between nodes as intermediate references to bound and correct navigation errors, achieving both GPS-denied operation and acceptable accuracy.
3Measurement precision
If RF or ultrasonic ranging sensors are added among group members, then range accuracy is sufficient, but directional information is lacking for accurate group navigation
Solution Approach 1:
The system segments the navigation problem into two independent components: range measurement and orientation measurement. Each node uses RF/ultrasonic sensors to measure distances to other nodes, while separate orientation sensors (magnetometers, accelerometers) measure directional information. This segmentation allows each sensor type to optimize its function while the system integrates both for complete navigation.
Solution Approach 2:
The patent makes each node multi-functional by equipping it with both ranging capabilities (RF/ultrasonic) and orientation sensing capabilities (magnetometers, accelerometers). Each node independently performs both distance measurement and direction measurement, eliminating the need for dedicated directional sensors and enabling self-contained navigation units that can determine both position and orientation.
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
SATS enables effective self and group location and tracking by correcting orientation and position errors, maintaining accurate navigation even without GPS, through dynamic adaptive processing and intelligent use of reference signals, thereby improving navigation capabilities in GPS-denied conditions.
Implementation Method 1
knowledge of all pair wise distances among all of the plurality of nodes
Implementation Method 2
A traditional approach to this problem relies on Inertia Measurement Units (IMU)
Data Source
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AI summary
A system and method for self and group location and tracking based on ultra wide band ranging among members of the group is presented. The system comprises an anchored station, a plurality of nodes, each node having at least knowledge of where the node is facing and heading, knowledge of all pair wise distances among all of the plurality of nodes, and ability to exchange information among the nodes and with the anchored station via relays. The system and method find a new position estimate of the group in accordance with an adaptive search process based on constraints of the ultra wide band ranging, and the search process enables extracting directional information and adaptively stabilizing orientation of the group. In one embodiment, adaptively stabilizing the orientation of the group is performed using an orientation-correcting polygon matching process.