mirror of
https://github.com/azaion/gps-denied-onboard.git
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Oleksandr Bezdieniezhnykh
51 lines
4.1 KiB
Markdown
51 lines
4.1 KiB
Markdown
# Position Accuracy
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- The system should determine GPS coordinates of frame centers for 80% of photos within 50m error compared to real GPS
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- The system should determine GPS coordinates of frame centers for 60% of photos within 20m error compared to real GPS
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- Maximum cumulative VO drift between satellite correction anchors should be less than 100 meters
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- System should report a confidence score per position estimate (high = satellite-anchored, low = VO-extrapolated with drift)
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# Image Processing Quality
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- Image Registration Rate > 95% for normal flight segments. The system can find enough matching features to confidently calculate the camera's 6-DoF pose and stitch that image into the trajectory
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- Mean Reprojection Error (MRE) < 1.0 pixels
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# Resilience & Edge Cases
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- The system should correctly continue work even in the presence of up to 350m outlier between 2 consecutive photos (due to tilt of the plane)
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- System should correctly continue work during sharp turns, where the next photo doesn't overlap at all or overlaps less than 5%. The next photo should be within 200m drift and at an angle of less than 70 degrees. Sharp-turn frames are expected to fail VO and should be handled by satellite-based re-localization
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- System should operate when UAV makes a sharp turn and next photos have no common points with previous route. It should figure out the location of the new route segment and connect it to the previous route. There could be more than 2 such disconnected segments, so this strategy must be core to the system
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- In case the system cannot determine the position of 3 consecutive frames by any means, it should send a re-localization request to the ground station operator via telemetry link. While waiting for operator input, the system continues attempting VO/IMU dead reckoning and the flight controller uses last known position + IMU extrapolation
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# Real-Time Onboard Performance
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- Less than 400ms end-to-end per frame: from camera capture to GPS coordinate output to the flight controller (camera shoots at ~3fps)
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- Memory usage should stay below 8GB shared memory (Jetson Orin Nano Super — CPU and GPU share the same 8GB LPDDR5 pool)
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- The system must output calculated GPS coordinates directly to the flight controller via MAVLink GPS_INPUT messages (using MAVSDK)
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- Position estimates are streamed to the flight controller frame-by-frame; the system does not batch or delay output
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- The system may refine previously calculated positions and send corrections to the flight controller as updated estimates
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# Startup & Failsafe
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- The system initializes using the last known valid GPS position from the flight controller before GPS denial begins
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- If the system completely fails to produce any position estimate for more than N seconds (TBD), the flight controller should fall back to IMU-only dead reckoning and the system should log the failure
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- On companion computer reboot mid-flight, the system should attempt to re-initialize from the flight controller's current IMU-extrapolated position
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# Ground Station & Telemetry
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- Position estimates and confidence scores should be streamed to the ground station via telemetry link for operator situational awareness
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- The ground station can send commands to the onboard system (e.g., operator-assisted re-localization hint with approximate coordinates)
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- Output coordinates in WGS84 format
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# Object Localization
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- Other onboard AI systems can request GPS coordinates of objects detected by the AI camera
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- The GPS-Denied system calculates object coordinates trigonometrically using: current UAV GPS position (from GPS-Denied), known AI camera angle, zoom, and current flight altitude. Flat terrain is assumed
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- Accuracy is consistent with the frame-center position accuracy of the GPS-Denied system
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# Satellite Reference Imagery
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- Satellite reference imagery resolution must be at least 0.5 m/pixel, ideally 0.3 m/pixel
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- Satellite imagery for the operational area should be less than 2 years old where possible
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- Satellite imagery must be pre-processed and loaded onto the companion computer before flight. Offline preprocessing time is not time-critical (can take minutes/hours)
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