UAVs Professional-Grade Navigation and Control Fusion Solution for the UAV Industry
In today’s rapidly developing UAV industry, GNSS navigation systems are facing increasingly severe environmental challenges. With the growing density of urban airspace, UAVs often need to fly close to buildings—where GNSS signals may be reflected by high-rise structures (multipath), reducing positioning accuracy. As anti-UAV technologies become widespread, the electromagnetic spectrum environment has become more complex, leading to frequent GNSS interference and spoofing incidents. In mountainous areas, valleys, and forests, signal blockage and jumps are common, making traditional single-frequency GNSS navigation unable to meet the demands of reliable, high-precision flight. Leveraging its profound expertise in industrial UAV applications, Hangzhou AGR Intelligent Technology Co., Ltd. (AGR) has selected Septentrio’s mosaic-G5 P3 GNSS module to address these complex environmental challenges.
Combined with AGR’s proprietary integrated navigation strategy and flight control system (AG6), it creates an industrial UAV platform capable of maintaining precise, stable, and safe navigation in harsh environments. In complex urban electromagnetic environments (such as dense 5G base station areas and industrial parks), the AIM+ advanced technology of the mosaic-G5 P3 module effectively mitigates various wireless interference signals. AGR’s flight control system continuously monitors navigation status and dynamically adjusts redundant navigation strategies to ensure the stability and safety of various UAV operations.
Core Challenges of Building Cleaning UAVs & Navigation Requirements
1. Safety Boundary Control During Ultra-Close-Proximity Flight
UAVs need to operate stably within 0.3–1.5 meters of glass curtain walls. Any horizontal or vertical positioning drift may cause collisions, leading to equipment damage or risks of falling objects from heights.
2. Dual Signal Interference from Urban Canyons and Curtain Wall Reflections
The “urban canyon” effect between dense buildings results in severe satellite signal blockage; large-area glass curtain walls and metal structures cause strong multipath reflections, seriously degrading positioning accuracy.
3. Rigorous Requirements for Platform Stability in Cleaning Operations
During cleaning, the reaction force generated by the brush disc or water spray device contacting the wall requires the UAV to have rapid and precise attitude adjustment capabilities to maintain a constant position, avoiding cleaning omissions or uneven patterns.
4. Long-Endurance Operations and Adaptability to Complex Weather
A single mission often lasts more than 30 minutes. The system must maintain continuous and reliable navigation output under temperature differences, gusts, and temporary signal blockage, while minimizing power consumption to extend endurance.
How the mosaic-G5 P3/P3H + AG6 Collaborative System Addresses Challenges?
1. Dual-Antenna Heading (P3H) + AG6 Heading Fusion for True North Lock and Wall-Parallel Maintenance
- The mosaic-G5 P3H delivers 0.15° heading accuracy with a 1-meter baseline, providing the UAV with true heading independent of magnetic interference.
- Through its built-in sensor fusion algorithm, the AG6 flight controller directly integrates dual-antenna heading as the primary heading reference, achieving absolute parallelism with building facades and avoiding cumulative errors.
- In steel structure areas or curtain wall frames with strong magnetic interference, traditional magnetic compasses may fail, while GNSS heading remains reliable.
2. AIM+ and APME+ Technologies Purify Urban Navigation Signals
- AIM+ (Advanced Interference Mitigation) real-time monitors and suppresses wideband and narrowband interference from in-building Wi-Fi, 5G base stations, and unknown radio frequency sources, ensuring the purity of signal tracking.
- APME+ (A Posteriori Multipath Estimation) specifically addresses complex multipath effects caused by glass curtain walls. Through post-processing estimation technology, it significantly reduces code and carrier phase errors, enabling horizontal positioning accuracy to remain at the centimeter level even in complex reflective environments.
3. High Update Rate and Low-Latency Positioning Empower AG6 for Precise Control
- The mosaic-G5 can output position/attitude information at up to 20 Hz.
- With its high-speed processing capability, the AG6 flight controller receives this high-bandwidth navigation data, enabling rapid updates of the control loop. This allows the UAV to respond instantly to gusts or contact reaction forces, maintaining precise tracking of cleaning paths.
4. Seamless Signal Interruption Handover to Ensure Operational Continuity
- When the UAV cleans balconies, recesses, or corners, satellite signals may be completely blocked for several seconds.
- The system achieves smooth seamless GNSS/INS switching through tight coupling between the mosaic-G5’s high-stability inertial aided output and the AG6’s built-in high-precision IMU. The AG6 can continue executing cleaning paths based on high-quality attitude and dead reckoning position data, ensuring uninterrupted operations.
Anti-Interference Test Case: JammerTest 2024 Results
Traditional GNSS receivers fail in challenging environments due to signal blockage, multipath reflections, and electromagnetic interference that cause positioning drift. During a five-day event in Norway, Septentrio receivers were tested against multiple competing receivers under various interference scenarios. The graph below shows a static test evaluating multiple receivers under extremely strong interference—signal strength 10 million times that of GNSS signals. The blue and red lines represent two competing receivers, which experienced positioning deviations of hundreds of meters due to interference. In contrast, the Septentrio receiver (orange line) demonstrated exceptional resilience to GPS/GNSS interference. It consistently provided accurate GNSS positioning while actively detecting and flagging interference signals. In real-world scenarios, loss of GNSS positioning can severely disrupt operations, leading to costly delays, reduced operational efficiency, and reputational damage. For example, an interfered UAV may lose control and crash. Even advanced UAVs equipped with autopilots may enter backup modes such as “hover,” “land,” or “circle,” or switch to alternative sensors like Inertial Navigation Systems (INS). However, without reliable absolute positioning, these sensors are prone to drift over time. Even in GNSS spoofing attacks, interference is usually first used to break the receiver’s “lock” on GNSS signals to increase the likelihood of spoofed signals being accepted during reacquisition.
Typical Operational Workflow
- Pre-Mission Modeling and Path Planning: Acquire a high-precision 3D model of the building via laser scanning or oblique photography, plan safe and efficient cleaning paths in professional software, and import them into the AG6 ground station.
- On-Site Deployment and Initialization: Set up an RTK base station and power on the UAV. The mosaic-G5 quickly obtains an RTK fixed solution in an open area, and the AG6 completes sensor calibration.
- Automated Cleaning Task Execution: The operator initiates the mission with one click. The UAV autonomously flies to the starting point and accurately performs wall-clinging cleaning based on centimeter-level positioning and heading. The AG6 real-time monitors system status and can transmit operational progress and images via a 4G link.
- Abnormal Handling and Safety Assurance: In case of sustained strong winds or severe signal loss, the AG6 will automatically execute preset safety strategies, such as vertically moving away from the wall to a safe distance or returning along the shortest path.
- Mission Completion and Data Transmission: After cleaning, the UAV automatically returns and lands. Complete flight trajectories, cleaning coverage reports, and system logs are available for download and analysis.
Frequently Asked Questions
In cost-sensitive projects, can the single-antenna mosaic-G5 P3 version be used for building cleaning?
Yes, but with limitations. The P3 version delivers the same centimeter-level positioning as the P3H, suitable for cleaning regular building facades where the UAV primarily flies in vertical or horizontal straight lines. For curved facades, corners, or complex paths requiring high heading accuracy, the dual-antenna heading of the P3H version is recommended for better safety and efficiency.
How does the AG6 flight control fuse data from the mosaic-G5 and its own IMU?
The AG6 uses advanced multi-sensor fusion. It takes centimeter-level position, velocity, and heading from the mosaic-G5 as a high-weight absolute reference, while the built-in IMU provides high-frequency angular velocity and acceleration data. The fusion algorithm uses GNSS as an anchor to correct IMU drift, outputting a combined solution that is both high-frequency and long-term stable.
How to achieve centimeter-level cleaning accuracy without a fixed base station network?
Two options: Network RTK (NRTK) via 4G/5G CORS services for real-time centimeter-level positioning, or PPK (Post-Processed Kinematic) where both the drone and base station record raw observation data for post-mission processing. PPK does not rely on real-time data links and is more robust in signal-blocked urban areas.
How does the building cleaning system perform in strong winds?
The system’s advantages are evident in strong winds. High-frequency, high-precision position feedback from the mosaic-G5 allows the AG6 flight control to quickly detect wind-induced path deviations and generate precise compensation commands. Stable heading from the P3H prevents the UAV from deflecting into the wall, forming a high-speed closed loop with wind resistance far superior to traditional low-precision GNSS solutions.
Related GNSS Products
- HB21 GNSS Box Receiver — All-in-one RTK receiver with integrated 4G LTE, heading, and data logging.
- HB6 GNSS Box Receiver — Compact quad-constellation RTK receiver powered by Septentrio Mosaic X5.
- EV322 GNSS Receiver — Lightweight RTK receiver for UAVs and autonomous systems.
- AIM+ Anti-Jamming Technology — Military-grade interference and spoofing protection.
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