Situations without satellite positioning can be divided into two main types. First, satellite connectivity may be unavailable when flying indoors. Second, satellite connectivity is cut off during an outdoor flight, such as by flying under a balcony or flying from indoors to outdoors. The loss of satellite positioning makes these scenarios dangerous for new pilots, or those who want to fly long distances*.If the drone wants to position itself using satellites, the flight controller needs the current location and flight speed of the aircraft. However, if the drone needs to position accurately without GPS, flight status and location will need to be collected another way. Vision positioning equipped drones generally use what is known as an Optical Flow visual positioning system, consisting of dual ultrasonic sensors and a single camera. The ultrasonic sensors provide altitude information by measuring the distance between the aircraft and the landing point, while the single camera is used to calculate positioning information by capturing images below the aircraft. As ultrasonic sensors are the only measure of height, the higher the aircraft flies the less precise the data from reflected sound waves become. Accurate height positioning is therefore limited to less than 3 meters. The single camera is unable to improve height positioning accuracy and limits areas that the drone can hover stably to those that have a clear and definable texture. The Mavic overcomes these problems through the use of dual forward vision sensors. This setup allows the Mavic to see obstacles in 3-dimensions up to 15 meters in front, increasing positioning accuracy to 2-3 times that of an Optical Flow system. It also allows the speed of the aircraft to be calculated, enabling precise hovering at up to 10 meters without satellite positioning. Dual forward vision sensors allow it to calculate its current location and speed of flight by observing the scene in front, further increasing positioning accuracy. Thanks to this precise hovering technology, the Mavic is able to automatically land almost exactly where you took off. Every time you take off, the two downward facing vision sensors record a burst of video of the ground below and pair it with satellite coordinates. When you tell the Mavic to fly home, it will return to that coordinate, match the video, and land back at your feet. *Line of sight flight is required in some countries.
No bumps and scrapes
Ultrasonic waves and Time of Flight (ToF) sensors are often used to measure distance from an obstacle, but both methods calculate distance based on signal reflection and are therefore reliant on the shape of the obstacle. This means distances from common obstacles such as rocks and branches cannot be sensed. FlightAutonomy gives the Mavic long range, high precision obstacle sensing, enabling it to scan its environment in 3D before taking off. FlightAutonomy ensures the Mavic precisely locates obstacles around it.Detecting obstacles requires getting information about the obstacle to the Mavic. Ultrasonic and ToF sensors measure distance by detecting the first reflected wave. In other words, they can only measure the distance from a single point, instead of getting a 3D depth image of a particular obstacle. Another method of creating a depth image is structured light projection. For this, a structured light sensor projects infrared in a specific shape onto the obstacle in front of it. The infrared then reflects back and the sensor then calculates the strength of the reflected signal so that it can create a 3D depth image of the obstacle. However, due to the limited strength of infrared and interference from visible light, the maximum sensing distance for a structured light sensor is only 3 to 5 meters. It is also ineffective in bright light significantly reducing its reliability and effectiveness on a sunny day.FlightAutonomy is made up of 7 components including 5 cameras (forward and downward dual vision sensors and the main camera), dual-band satellite positioning (GPS and GLONASS), 2 ultrasonic rangefinders, redundant sensors, and a group of 24 powerful, specialized computing cores. Cameras on the left and right side in the front of the Mavic are fixed in place using an aluminum bracket to ensure the optimum alignment of the vision sensor lenses. As the Mavic flies, dual forward and downward vision sensors measure the distance between itself and obstacles by taking photos from all four cameras and using the information to create a 3D map that tells it exactly where obstacles are. The dual forward and downward vision sensors require visible light to function, and in bright light can see as far as 49ft (15m) out in front.This obstacle avoidance system is activated in every Intelligent Flight Mode including all ActiveTrack modes, TapFly and Terrain Follow. It is also available during automatic Return to Home, so that the Mavic can easily make its way back without bumping into anything in its path.