Test methodology for evaluations of soldier positioning systems
Publish date: 2013-12-31
Report number: FOI-R--3819--SE
Pages: 27
Written in: English
Keywords:
- Soldier positioning system
- test and evaluation
- GPS
- inertial sensors
Abstract
A positioning system provides the core functionality in dismounted soldier command and control (C2) support system. Existing indoor positioning systems will not provide sufficient room- or floor-level position accuracy. A multisensor system approach is required in order to achieve the desired performance in terms of position accuracy and system reliability. There is a need to perform independent test and evaluations of the positioning systems, since the performance provided by industry typically only covers tests that have been performed during ideal conditions. The soldier C2 support system will be composed of several systems, including a positioning module, a radio system providing reliable voice and data transfer within the squad, and an intuitive user interface module. The proposed test methodology only targets test and evaluation (T&E) methods for the positioning system module. Many different factors affect the positioning accuracy, and the sensor fusion poses several challenges that can seriously reduce the position accuracy in specific scenarios. Therefore, the test methodology should be based on knowledge about the strengths and vulnerabilities of different technologies, and potential pitfalls for the sensor fusion implementations. Since the performance depends on factors such as the trajectory, type of motion, and environment, it is crucial that controlled-environment evaluations can be complemented with evaluations performed during realistic conditions through scenario-based evaluations. The test suite should be designed to clearly and objectively pinpoint any weaknesses, design errors or sensor shortcomings in the system under test. It is crucial that the test and evaluation can capture the expected performance during realistic conditions in dismounted soldier operations. The reliability of the position uncertainty estimate provided by the system must also be evaluated. The proposed test methodology includes simulator lab tests, repeatable dynamic tests, and full-scale scenario-based evaluations that try to capture realistic soldier behavior. The following aspects are of interest to test: (a) the worst-case performance in terms of distance-scale and heading errors in straight line movement tests, (b) typical performances expected in real operations, through a combination of repeatable dynamic tests and scenario-based tests,(c) the quality of the GPS/INS-integration in urban environments, (d) how the positioning system is affected by GPS jamming and spoofing signals, and if they are able to detect such signals, (e) the effects of local magnetic field perturbations as well as air pressure variations, and (f) the performance of the inertial sensors during high dynamics. A combination of different evaluation criteria should be used. In most situations it is sufficient to provide information about the average and maximum position and heading errors, and their standard deviations, as a function of time. However, information about the test settings, such as how the soldier moved, must also be provided.