CATEC has successfully completed and flight-validated at its ATLAS centres its new GNSS-free navigation technology – designed for use in GNSS-denied environments and hostile operational zones – specifically aimed at its application and transfer to the drone/UAS sector in the field of defence and security.
This is a highly advanced navigation system developed in-house by CATEC, which is at the forefront internationally. It relies solely on on-board sensors to estimate position, speed and orientation relative to the take-off point, and all processing takes place entirely on board the aircraft, without the need for prior information about the environment in which it is deployed, nor for external infrastructure or communications with other systems. This solution stands out for its compact size and light weight, making it particularly attractive for integration into other fixed-wing or rotary-wing aircraft of various sizes and flight dynamics.
An initial version of the system was presented in April during the Spanish Army’s third Tactical Experimentation Campaign 2026 (TEC-3), held at the ‘Álvarez de Sotomayor’ Base in Viator (Almería), which aimed to validate new capabilities and technologies as part of the Army’s transformation process. The system was validated under real-world field conditions, covering distances of up to 5 km with a cumulative error of around 100 metres (2%).
Following this initial verification, CATEC has continued to refine its solution to further optimise the robustness and accuracy of the estimates, and to enhance performance aspects such as flight speed, through a series of tests at its ATLAS centre, until it was successfully validated in an operational environment.
CATEC’s CEO, Joaquín Rodríguez Grau, emphasised that “this solution represents a cutting-edge technological advance, based exclusively on on-board sensors and requiring no prior environmental data, external infrastructure or communications with other systems; it is fully mature and ready for transfer to the defence sector. This international milestone places Spain at the forefront of the capabilities available to this industry, with technology that is 100% nationally owned, providing a unique strategic advantage in terms of precision, reliability and operational efficiency”.
New technological capabilities
To complete this GNSS-free navigation solution, CATEC has incorporated its capabilities and expertise in visual-inertial odometry (VIO) and advanced sensor fusion techniques, which enable the autonomous positioning and navigation of aircraft in environments where the GNSS signal is degraded or completely unavailable, thus creating a robust solution that fuses visual and inertial data from on-board sensors, ensuring reliable estimates even in adverse conditions and without the need for existing or additional infrastructure.
The use of a VIO algorithm enables the real-time estimation of an aircraft’s position, velocity and orientation by combining information from one or more on-board cameras and an inertial sensor (IMU), which is essential in environments where GNSS signals are degraded or denied, as is the case during operations in areas at risk of interference. In this way, incorporating the VIO algorithm combines the best of each system: in odometry, the ability of vision to provide absolute information about the environment, and the speed of the IMU to track rapid movements and scenes with poor texture.
Furthermore, the system has been enhanced through the use of probabilistic optimisation techniques for sensor fusion, which enable the optimisation of a time window of states, making better use of historical data and correlations between sensors. In UAS navigation, this approach is particularly useful in degraded or denied GNSS environments, as it enables the robust integration of heterogeneous and asynchronous measurements, the detection of inconsistencies and the reduction of cumulative drift. Consequently, these techniques are particularly well-suited to advanced multi-sensor navigation architectures, where high accuracy, resilience and the ability to incorporate new sources of information without completely redesigning the estimator are required.
