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. CAN (4P GH1. 25mm with DroneCAN protocol) DroneCAN Optical Flow | Vimdrones Can Flow | Ardupilot | PX4 | AP_Periph 1. 6 | PMW3901 | VL53L1X | Open Source Dronecan Optical Flow and Distance Sensor Module Specification Type Value Power supply 5V Support Flight Controller Firmware Ardupilot | PX4. If the vehicle has a GPS, the inflight calibration procedures is the easiest way to get a good calibration: An alternative method which avoids the need to land and change EKF3 parameters between calibration and testing is to setup GPS/Non-GPS transitions so the pilot can manually change between GPS. ArduPlane, ArduCopter, ArduRover, ArduSub source. I want to say that the ArkFlow is working amazingly, way better than the PX4Flow we had previously. – Alin Grig Have used them and they're top notch! – Ryan Johnston Building a DIY indoor optical flow drone can be difficult if you don't know where to start, but there's good news! In this post, I will break down every single step required to build your own optical flow drone.