NAVISAR
About the Project
Aerial vehicles greatly rely on GNSS (Global Navigation Satellite System), such as GPS (Global Positioning System), for precise absolute navigation. However, GNSS is vulnerable to jamming and spoofing which is likely to be encountered in the mission area of military vehicles.
Therefore, alternative absolute navigation means are required in case that GNSS is unavailable (e.g. jamming) or unreliable due to spoofing.
The scope of the project “NAVISAR” is to develop and study a navigation system making use of a Synthetic Aperture Radar (SAR) for GNSS-denied navigation. The ultimate goal of this project is the demonstration of the investigated technology hosted on a generic aerial platform.
The SAR (Synthetic Aperture Radar) is an active sensor working in the microwave bands of the electromagnetic spectrum. It takes advantage of the moving platform on which it is mounted to imitate a large (synthetic) antenna array with high spatial resolution which is otherwise unattainable with on-board Real Aperture Radar.
Key Objectives and Operational Capabilities
Compared to Vision-based navigation (VBN) based on an electro optical sensor, the SAR sensor comes with the following advantages:
- “All weather conditions” operability;
- “Day & Night” operability;
- Coverage of wide areas on the ground (up to several square kilometres) from a long distance (up to tens of kilometres);
- Resolution independent from the distance;
Project Foundation and Impact
Therefore, SAR navigation is more robust in GNSS denied environments, being independent from particular conditions of the operational scenario. Moreover, it is more difficult for a SAR sensor to be subject to spoofing and jamming attacks.
A further advantage of the proposed solution is that the SAR sensor is typical a mission sensor (e.g. a seeker for target detection and localization or surveillance), and hence, not additional sensor installations may be required on the platform.
This proposal is aimed at tackling the following challenges:
- Pre-Selection and implementation of image processing algorithms for extraction of navigation information from SAR images based on AI and “classical” image processing approaches
- Conduct a performance study thereof comparing these different methods
- Sensor fusion of the Inertial Navigation System (INS) and the navigation information extracted from the SAR based system. This includes a “SAR sensor model” to compensate for internal errors
- Assessment of the NAVISAR system performance in simulation and in live flight demonstration
- Providing technical recommendations for a best possible SAR-based navigation solution, including insights about the challenges, potential improvements and limitation of the NAVISAR system in the context of the operational scenarios.
