To implement this mode, an optical flow sensor and a Time of Flight (TOF) sensor are needed. Height-hold mode: keep flight height. 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 HereFlow optical flow sensor is a lightweight optical flow sensor including a short range lidar which uses the CAN protocol to communicate with the autopilot. These sensors help maintain a stable hover by providing precise data about the drone's position and altitude. This drone comes with simple-structured hardware, clear codes, and supports functional extension. Optical Flow based navigation is supported by all three estimators: EKF2, LPE and INAV (see below).
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