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GNSS-Denied Navigation Kit: POLAR-300 & VNS01 Accurate Navigation in Hostiles Environments

Accurate Navigation in Hostiles Environments

 

Introduction

As technology advances and geopolitical challenges arise, the demand for reliable and secure navigation for Unmanned Aerial Systems (UAS) intensifies. Ensuring operational integrity in both civil and defense sectors is paramount. The arrival of systems designed to disrupt radio-electronic navigation and communication accentuates this need. With GNSS signals increasingly under threat from both unintentional and intentional interference, the shortcomings of traditional navigation systems are evident.

The navigation kit consisting of the POLAR-300 and the Visual Navigation System (VNS01) emerges as a groundbreaking solution to these challenges. Immune to external disruptions, VNS01 represents the future of autonomous navigation. This whitepaper delves into the unparalleled capabilities of the kit, highlighting real-world scenarios where it navigates with precision even when conventional systems falter.

Disruptions to GNSS signals can arise from various sources, including natural phenomena, technical glitches, and, more concerning, deliberate interference or jamming by adversaries that threaten the integrity of GNSS signals. In this document, we will focus on the latter, which can be categorized into two types of attacks: Jamming, where the GNSS signal is intentionally inhibited, and spoofing, which is even more dangerous, as adversaries simulate a GNSS signal to deceive the aircraft leading it to crash or redirect to an unintended location.

When faced with such disruptions, the implications can be devastating for operations that depend solely on these signals for navigation. In situations where every second is crucial, such as in time-sensitive military operations or emergency responses, even slight deviations from the planned route or brief navigational interruptions can result in catastrophic outcomes. The escalating occurrences of GNSS signal interruptions emphasize this weakness, creating a pressing need for a more resilient navigational solution.

Jamming refers to the deliberate disruption or interference with GNSS signals. This interference overwhelms the genuine GNSS frequencies with noise or other interruptions, making it challenging to receive the original signal and often leading to lost connections or inaccurate data. The dangers of jamming are significant. Systems that rely heavily on GNSS might find themselves without navigation, potentially going off-course, jeopardizing their mission, or exposing assets to risks.

Spoofing, on the other hand, involves creating and transmitting fake GNSS signals. Rather than merely disrupting the signal as jamming does, spoofing deceives a GNSS receiver into thinking it is receiving a legitimate signal. This deception can produce entirely false positioning data, leading users to navigate inaccurately. The risks of spoofing are significant. Sophisticated spoofing attacks can allow adversaries to take over a system or vehicle, potentially redirecting it or causing it to crash.

 

Advance Navigation Solutions: Overcoming GNSS Limitations

The POLAR-300 AHRS is integrated with the VNS01 Visual Navigation System, which features an onboard camera that captures and processes images throughout the flight. This allows for the creation of an internal map for use when GNSS is unavailable. When processing these images, the VNS01 employs three techniques to ensure accurate determination of absolute position, orientation, and relative movement.

Visual Odometry: Visual navigation is based on “odometry”; in other words, calculating the offset of singular points in consecutive frames. It does not know the absolute position, but it does tell you how much you have moved, with a small margin of error based on the distance traveled.

Pattern Recognition: This technique is based on the search and identification of characteristic points with images captured in real-time versus a geo-referenced pre-stored collection. Once GNSS is lost, the VNS01 will start searching for a match between A and B to find out its absolute position. Once a match is found, the navigational error is reduced drastically.

Dead Reckoning with POLAR-300: In situations where the VNS01 is unavailable, such as when flying above the clouds or over the ocean, GNSS-denied navigation remains possible thanks to the POLAR-300. The POLAR-300 is equipped with a state-of-the-art Inertial Measurement Unit (IMU), which allows for dead reckoning navigation. While this technique is based on estimations and can accumulate errors over time, the IMU in the POLAR-300 is highly precise, providing more reliable data than conventional solutions.

 

Beyond Dead Reckoning: The Approach of Grupo Oesía to Adaptive UAV Navigation in GNSS-Denied Operations

When conventional systems lose GNSS signal, they are compelled to rely on dead reckoning navigation. However, due to the use of less accurate sensors and the inherent vibrations of such aircraft, errors accumulate. Over time, these errors can result in the aircraft deviating by several tens of kilometers from its intended operational area. Fortunately, the VNS01 addresses this challenge. Its camera continuously captures real-time images, enabling it to determine its position and trajectory accurately.

With each mission, the system learns and adapts, enhancing its precision and reliability and thereby reducing the reliance and associated risks of dead reckoning navigation.

 

Real-World Assessment

Overflying Known Areas: When flying over areas that have been previously covered, the VNS01 has an internal map it previously generated. In the event of a GNSS signal loss, this pre-existing map enables the system to navigate effectively. In actual tests conducted using advanced spoofing and jamming techniques, the system exhibits virtually no positional error in such situations.

Overflying known and unknown areas: Another common scenario involves aircraft taking off without GNSS from areas that they have previously covered and for which maps are already stored. At the same time, these aircraft might also fly to areas they have never flown over, meaning no maps would be available. In such situations, based to the tests conducted, the aircraft maintains an error of about 1% of the total distance traveled.

Overflying Unknown Areas: The most demanding test conducted involved flights in an entirely unknown area, without any available internal map and without a GNSS signal from start to finish, all while under constant spoofing attacks. In such challenging conditions, the system managed to maintain a positional error of about 1% of the total distance traveled.

Loitering at Unknown Locations: To prove the learning and adaptative capabilities of the VNS01 in unfamiliar terrains, the objective was to perform a loitering flight over an unknown area without the presence of GNSS. To maintain a minimal error, despite the absence of maps or GNSS, the VNS01 had to adapt to the operational conditions and remember the areas it was flying over. Even though it cannot generate high-quality maps, it must ensure its error does not increase over time. In these tests, after flying for an extended period, the error was only 0.5% of the total distance traveled.

Dead Reckoning with POLAR-300: Lastly, the final tests involved flights without the VNS01, relying exclusively on the capability of the POLAR-300 to perform dead reckoning navigation using only its inertial sensors. In these flights without GNSS, the accumulated error was 10% of the total distance traveled.

 

Conclusion

This Navigation Kit presents a monumental leap in GNSSdenied navigation solutions. It offers clear distinctions from other market alternatives, such as passive solutions and antijamming antennas, which predominantly rely on the GNSS signal and their capacity to repel the attacks they face. Unlike these alternatives, the VNS01 does not focus on countering attacks directly. Instead, it uses its internal capabilities to navigate accurately under all conditions.

Real-world performance metrics highlight the resilience and stability of this kit, especially in spoofing conditions, showcasing minimal drift. Most other navigational tools in the market exhibit significant deviations under identical challenges. The huge contrast in drift, especially in dead reckoning scenarios without the VNS01, underlines the unmatched ability of navigational precision offered by the POLAR-300 and the VNS01 acting as one.

 

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About

UAV Navigation is a privately-owned company that has specialized in the design of flight control solutions for Unmanned Aerial Vehicles (UAVs) since 2004. It is used by a variety of Tier 1 aerospace manufacturers in a wide range of UAV - also known as Remotely Piloted Aircraft Systems (RPAS) or 'drones'. These include high-performance tactical unmanned planes, aerial targets, mini-UAVs and helicopters.