Optical Flow uses a downward facing camera and a downward facing distance sensor for velocity estimation. It can be used to determine speed when navigating without GNSS — in buildings, underground, or in any other GNSS-denied environment. The video below shows PX4 holding position using the Ark. The LiteWing Flight Positioning Module uses the PMW3901MB optical flow sensor to measure horizontal motion relative to the ground. Instead of relying on GPS, this sensor tracks visual features on the surface beneath the drone and reports how those features move between frames. The PX4FLOW is not yet supported in Plane or Rover. It is well known for frame-based cameras, but given this new event-based paradigm, we adopt new approaches to achieve this goal, while preserving the asynchronous. Source suppliers and manufacturers of optical flow sensors for drones, UAVs, and other unmanned systems.
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