3.5 Research Assignment: UAS Sensor Placement


Research Assignment: UAS Sensor Placement
Preface, This topic is of particular interest to me as I own both of the UAS being discussed in this assignment/blog posting. The DJI Mavic Air, and the Armattan Rooster FPV racing/freestyle Quadcopter.
First Person View Drone Racings is gaining rapid popularity thanks to the Drone Racing League being featured on ESPN, local racing events held by Multi GP, and freestyle flying as seen on the popular youtube channel Rotor Riot. The high speed quadcopters are built to be fast and durable typically touting carbon fiber frames, high thrust motors, and advanced flight controllers.
The Armattan Rooster is a Racing/Freestyle frame that can be customized by the builder or purchased as a complete drone. My personal Rooster was built using a CLracingF4s Flight controller, and a 4 in 1 Spedix 30 am ESC, 4x TMotor F40 Pro v2s, a TBS unify pro video transmitter, and a TBS crossfire long range low latency receiver. The onboard FPV camera is a Runcam Eagle 2 Pro which is an 800TVL CCD. The video transmitting antenna is the luminaire AXII right hand circular polarized stubby and is attached with a 3d printed mount. The advantage of the Rooster frame is that it has a titanium cage surrounding the FPV camera and offers an adjustable positioning of the FPV camera. It includes an angled mounting surface for a high definition action camera like the gopro hero5 Session. The camera angle of both the FPV camera and the HD camera is important because it significantly impacts the speed at which the drone can be flown. When flying, the camera is in a fixed position and the pilot is seeing through it via FPV goggles.
Lower Camera Angle, less forward pitch, less speed

Higher Camera Angle, more forward pitch, more speed

The drone increases its speed as it is pitched forward. It is ideal to keep the ground and the horizon in the field of view while traveling forward for reference. The further forward the drone is pitched, the faster it will travel forward. In order to maintain the proper field of view while the drone is pitched further forward, the camera must be angled upwards. This also helps to keep the propellers out of the cameras view which can be distracting for many pilots.
There are other on board proprioceptive sensors that detect the health and status of the drone while it is flying and presents the data directly in the FPV goggles on screen display. These sensors detect the current draw from the battery, the remaining milliamp hours, and the current battery voltage. The RC receiver signal strength indicator is also able to be displayed in the goggles, to help a pilot know if his drone is too far away and he is in danger of losing control link to the aircraft. While the rooster in this configuration does not have a magnetometer, barometer or compass, built into its flight controller, there are many flight controllers that do have these features available, and would allow things like heading and altitude to be displayed in the goggles as well.
The DJI Mavic Air is DJIs newest addition to their commercial/professional drone line up. It is designed as an ultraportable, high end flying camera with the ability to capture stunning photos and 4k ultra high definition video.  It hosts and impressive list of proprioceptive and exteroceptive sensors to include front at rear obstacle detection from 6 different cameras positioned around the drone. “In addition to the traditional cameras, the Mavic Air has a pair of infrared sensors that face the ground to help create a 3D map of the environment below.” 
The Mavic air has redundancy in virtually all of its systems to include dual IMUs for increased reliability. The aircraft is constantly thinking about where it is and where it has been, creating a map of its surroundings and even imaging the ground where it took off from, so it can try to land in the exact same spot. While the Air is not designed as a racing drone, it can still be flown quickly in “sport mode” which allows it to fly up to 45 mph and can be used with DJIs Racing FPV goggles. The Mavic Air has more sensing technology than any other drone in its class. Its video and photographic capabilities are outstanding and it portability is unrivaled.




References
Charlton, A. (2018, April 04). This drone is a masterclass in downsizing. Retrieved from https://www.gearbrain.com/dji-mavic-air-drone-review-2556226252.html
Horaczek, S. (2018, January 23). DJI's Mavic Air Drone uses more than a dozen sensors to keep it from crashing. Retrieved from https://www.popsci.com/dji-mavic-air-sensors-object-avoidance#page-2
Liang, O. (2018, January 26). Review: Runcam Eagle 2 Pro FPV Camera. Retrieved from https://oscarliang.com/runcam-eagle-2-pro-fpv-camera/

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