Research Online: Laser localization system implementation, UAS sense and avoid integrity

May 13, 2016  - By
Image: GPS World

Implementation of a Laser Localization System

By Aidan F. Browne and David Vutetakis, The University of North Carolina at Charlotte.
Presented at IEEE/ION PLANS 2016 in Savannah, Georgia.

A novel laser-beacon localization system has been developed that has applications in positioning and navigation of mobile ground or aerial vehicles where other forms of localization are absent (such as GPS). The system allows for accurate position determination within an area of interest with reasonable accuracy.

The overall operation of the system is accomplished using only two external co-located beacons and a single on-board detector to perform pseudo-triangulation. The two beacons are spaced two meters apart, and continuously scan the area of interest in a sweeping fashion. As a beacon sweeps across the area of interest, its instantaneous angle is encoded in the pulse frequency of its emitted laser beam using a unique range of frequencies. A rotating detector on the vehicle is continually scanning over a 360-degree arc; it captures and decodes received beacon information in combination with its own relative angle at time of receipt.

The system has been successfully modeled in MATLAB to evaluate its effectiveness in terms of spatial localization accuracy under thousands of scenarios as well as to analyze the effects of the error parameter variations.

A prototype of the system has been realized using stepper motors, TTL-modulated 4.5 milliwatt line-generating lasers and a transimpedance amplified photodetector. Initial system testing has been promising with consistent results, indicating that the assumed error levels for the model were reasonable. Testing is underway to validate the results of the model and demonstrate the feasibility of the system.

UAS Sense and Avoid Integrity

By Michael B. Jamoom, Mathieu Joerger, and Boris Pervan, Illinois Institute of Technology
Presented at IEEE/ION PLANS 2016 in Savannah, Georgia.

Sense and avoid (SAA) concepts and methods can be tools for certification authorities to set potential requirements for integrating unmanned aircraft systems (UAS) into the National Airspace System.

One new method seeks to ensure the safety of SAA functions for UAS in the presence of multiple intruders. Integrity and continuity are used as quantifiable safety performance metrics, and are addressed though determination of the probability of data mis-associations for multiple intruders. A miss-association occurs when the system incorrectly associates one intruder’s measurement with another intruder’s trajectory. Incorrect intruder associations are hazardously misleading information, impacting integrity. Likewise, a detected mis-association can result in a break in the continuity of the SAA operation.

A sensitivity analysis is performed based on two two-intruder encounters. The resulting impact of mis-associations between multiple intruders on integrity and continuity is quantified for a nominal composite SAA sensor.