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 advent 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.
UAV Navigation-Grupo Oesía offers a robust solution that combines different technologies to address these challenges. Immune to external disruptions, this solution represents the future of autonomous navigation.
Disruptions to GNSS signals can arise from various sources, including natural phenomena, technical glitches, and, more concerningly, 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 navigation interruptions can result in catastrophic outcomes. The escalating occurrences of GNSS signal interruptions emphasize this weakness, creating a pressing need for a more resilient navigation solution.
- Jamming: Jamming refers to the deliberate disruption or interference of 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, spoofing involves creating and transmitting fake GNSS signals. Rather than merely disrupting the signal as jamming does, spoofing deceives a GNSS receiver into thinking it's receiving a legitimate signal. This deception can produce completely false positioning data, leading users to navigate inaccurately. The risks of spoofing are profound. Sophisticated spoofing attacks can allow adversaries to take over a system or vehicle, potentially redirecting it or causing it to crash.
Overflying known areas
When flying over areas that have been previously covered, the VNS01 has a pre-generated map in its internal memory. 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.
Overflying known and unknown areas
Another common scenario involves aircraft taking off without GNSS from previously covered areas, for which maps have already been generated and stored in VNS01 memory. At the same time, these aircraft might also fly to areas they have never flown over, meaning no stored maps would be available. In such situations, based on internal tests, the system is capable of the aircraft maintaining an error of about 1% of the total distance traveled.
Figure 1: VNS01 drift after 6 km of unknown zone
Note: The target icon in the image represents the real system position according to the internal GNSS information. The arrow, barely appreciated under the aircraft icon, indicates the aircraft's estimated position as reported by the VNS01. The aircraft icon shows the position of the aircraft as estimated by the FCC.
As soon as the aircraft enters the known zone, the VNS01 cancels the positional error, as illustrated in the picture below.
Overflying unknown areas
The most challenging scenario for the system involves 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. With such challenging conditions, the system manages to maintain a positional error of about 1% relative to the total distance traveled.
Figure 2: Drift after one loop in the unknown FP
Loitering at unknown locations
To demonstrate the VNS01’s learning and adaptation capabilities in unfamiliar terrains, a test involving the execution of a loiter maneuver over an unknown area with no GNSS availability is carried out. To maintain a minimal error, despite the absence of maps or GNSS, the VNS01 adapts to the operational conditions and recognizes the area where it has been flying over. Even though it won´t be able to generate high-quality maps, it must ensure its error does not increase over time. In these tests, after flying for an extended period, the accumulated error reaches only 0.5% of the total distance traveled.
Dead Reckoning with POLAR-300
Lastly, the final tests involve 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 is expected to be 10% of the total distance traveled.
Figure 5: Inertial navigation accumulated drift after 6.6 km
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Summary
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Test
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Description
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Distance covered
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Drift (m)
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Drift (%)
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1
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Known areas (map available)*
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4 km
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0 m
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0 %
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2
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Unknown areas (no map available)**
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7 km
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80 m
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1.1 %
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3
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Loitering in unknown areas (no map available)
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16.7 km
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90 m
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0.5 %
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4
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Flight without VNS01
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6.6 km
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690 m
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10 %
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*Known areas are previously overflown regions. Therefore, the VNS01 has a map available..
**Unknown areas are regions that have not been previously flown over. Therefore, the VNS01 lacks an available map.
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MECHANICAL / ENVIRONMENTAL
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POLAR-300 Size (mm, H x W x L)
POLAR-300 Weight
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22 x 40 x 82 mm
76 g
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VNS01 Size (mm, H x W x L)
VNS01 Weight
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POLAR-300 Connector
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Glenair MWDM2L-15PCBR-.080
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VNS01 Connector
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Binder 86 6319 1120 00008
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Static / Pitot Port Diameter
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3.0 mm
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Humidity
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Up to 90% RH, non-condensing
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Temperature Range
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-40 ºC to +85 ºC
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Shock Survival
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500 g. 8 ms.1/2 sine
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ELECTRICAL
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Input Voltage
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9 to 36 V DC
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POLAR-300 Power Consumption
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1W (@ 12 VDC)
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VNS01 Power Consumption
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5W (@ 12 VDC)
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GNSS Antenna Connector
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50 Ohm SMA Female
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AIR DATA SYSTEM (ADS)
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Airspeed Range
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15-220 kt
43-450 kt (Under request)
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Airspeed Accuracy
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±3 % reading
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Airspeed Precision
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± 1 kt
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Altimeter Range
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-2,000 to +36,000 ft AMSL
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Altimeter Accuracy
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±3 % reading
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Altimeter Precision
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± 1 ft
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MAGNETOMETER
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Internal Magnetometer
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3 Axes
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Calibration
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3D/2D
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Sensitivity
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0.1 μT
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TYPICAL DEAD-RECKONING DRIFT FIGURES
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POLAR AHRS without Visual Navigation System
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4% of distance traveled
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POLAR AHRS with Visual Navigation System at Unknown Terrain
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1% of distance traveled
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POLAR AHRS with Visual Navigation System at Known Terrain
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No Drift
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DYNAMIC ACCURACY
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Roll/Pitch Error
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< 0.5º
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Heading Error
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< 1º
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Estimated Position Accuracy (GNSS available)
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2.5 m CEP, GNSS & SBAS available
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REDUNDANCY & SAFETY
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Online Sensor Diagnosis
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Yes
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Sensor Failure Tolerance
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All Single
Several multiple
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MTBF
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Over 60,462 h
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GNSS
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Receiver Type
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72 Channel, L1C/A, L1OF, B1I, E1B/C
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GPS, GLONASS, BeiDou, Galileo, QZSS, SBAS
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Time to First Fix (Cold / Hot)
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< 26 s / < 2 s
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Altitude / Velocity Limit
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50,000 m / 500 m/s
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Navigation Update Rate
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5 Hz
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GNSS PPS
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Horizontal Position Accuracy
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2.5 m (CEP, 50%, 24 h static, -130 dbm, >6 SVs)
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Heading Accuracy
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0.4o Dynamic (50% @ 30 m/s)
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Dual GNSS Compass / External GNSS
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External Payload Available (DGC01)
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The kit comprises a VNS01 - Visual Navigation System, a POLAR-300 AHRS, and all the necessary ancillaries for the installation and connection of both systems to Visionair, enabling the reception of positioning and navigation data:
The kit includes the following software components:
- Visionair Dongle
- Visionair Analytics software
- LibUtils libraries. Libutils is included to ease the integration process of the system. Support Service:
- 10 hours of the Premium Support package
To further understand the capabilities of the GNSS-Denied Navigation Kit, this section describes various schema setups that will help users learn more about the precise estimation capabilities of the Kit.
Laboratory Testing
The laboratory environment provides an ideal opportunity to become familiar with the GNSS-Denied Navigation Kit in a controlled and safe setting. In this setup, the system is installed directly in the lab and connected to a PC using our Command and Control software: Visionair. For a straightforward integration, this connection can be established via a serial cable. Alternatively, wireless datalinks can be used for a more advanced simulation. This approach allows for performance evaluation, fine-tuning, and a deeper understanding of the system’s behavior before deployment in real-world scenarios.
Test as a Flight Passenger
In this second scenario, the system is tested in a more realistic environment by being onboard an aircraft as a flight passenger. The GNSS-Denied Navigation Kit, through its two main components, the Visual Navigation System VNS01 and our AHRS, the POLAR-300, collects real-time flight data throughout the mission, offering valuable insights into system performance under real operating conditions. This data can be monitored live via our GCS software, Visionair, or recorded for post-flight analysis using our Flight Data Recorder, FDR01. This method allows for a thorough evaluation of system behavior in dynamic scenarios without requiring control of the aircraft, making it ideal for validation and fine-tuning.
Integration of GNSS-Denied Navigation Kit with a third-party FCC
This setup is ideal for customers who operate their own autopilot systems but require a robust navigation solution for missions in contested environments—capabilities that their current Flight Control Computer (FCC) may lack. UAV Navigation–Grupo Oesía addresses this need with its GNSS-Denied Navigation Kit, which combines the POLAR-300, an advanced AHRS delivering high-reliability inertial navigation, and the Visual Navigation System VNS01, which significantly reduces accumulated drift. Together, they enable precise navigation in GNSS-denied scenarios. To ensure smooth integration, we provide detailed technical documentation and support, allowing customers to enhance their system’s performance and expand mission capabilities with confidence.
Integration of the Visual Navigation System with a third-party FCC
This setup offers an effective solution for customers operating in GNSS-denied environments who rely on inertial navigation but experience excessive drift over time. By integrating UAV Navigation–Grupo Oesía’s Visual Navigation System (VNS01), inertial drift is significantly reduced thanks to real-time visual corrections, enhancing overall navigation accuracy. This allows customers to maintain their existing FCC while upgrading their navigation performance. To facilitate the integration, we provide full technical documentation, including our Communication Interface Control Document (ICD), ensuring a smooth and efficient implementation of the VNS01 into third-party systems with confidence and minimal development effort.
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