Have you ever encountered such an emergency flight situation?
1. The drone suddenly enters the attitude mode when taking aerial photos among high-rise buildings, which leads to crashing into the building and bombing the plane?
2. During the flight, the drone suddenly drifted in a specific area, the image transmission black screen, and even the remote control stick was invalid.
The above situation is because the GPS signal of the UAV is blocked or shielded, and the remote control signal is interfered, which poses a great challenge to flight safety.
Although the positioning accuracy of EVO II is already in the leading position in the indoor environment without GPS, the pursuit of Autel Robotics engineers for the ultimate user experience is far more than this. In response to the pain points of user feedback, a black technology function has been developed on the EVO II series drones - the high-altitude non-GPS return function, which escorts the flight safety of drones.
The return-to-home function without GPS at high altitude relies on VIO technology, so the question is, what is VIO? How does this technology work? What are the precautions?
1. What is VIO?
VIO technology (Visual-Inertial Odometry positioning system), the Chinese name is visual inertial odometer. Through the visual sensor and the IMU (Inertial measurement unit) inside the fuselage, precise image comparison and positioning can be realized, and the flight function of memory cruise can be achieved.
Most drones rely on GPS for positioning when flying. GPS antennas have poor positioning effect when the clouds are relatively thick. The reason for the low accuracy. If the GPS signal is directly blocked by the outside world, then the drone is like a ship floating in the sea. If it does not anchor, it will drift with the current and cannot be located.
In addition, the drone's GPS signal will be blocked between tall buildings, and it will also enter the attitude mode. The result of the performance is attitude drift. After encountering obstacles, it will eventually lead to bombing.
The above situation requires a technology that does not rely on GPS for positioning - VIO technology.
2. What is the working principle of VIO technology?
VIO technology requires vision sensors and IMUs to work together.
A single visual sensor has its own defects. When the camera moves rapidly or the lighting changes drastically, and the ground texture has no obvious features, the visual sensor will lose some tracking information.
So at this time, another "helper" IMU is needed to work together. The acceleration and angular velocity information of the IMU can significantly improve the scene where the visual sensor cannot cope with fast movement, so that the data fusion of the visual sensor and the IMU can achieve the ideal positioning effect.
When the GPS signal of the UAV is blocked, with VIO technology for auxiliary positioning, the UAV can maintain a stable attitude so as not to bomb the aircraft.
3. How powerful is EVO II with high-altitude VIO technology?
Some drones on the market also use VIO technology, but when the flying height exceeds 30 meters, the positioning effect is not ideal.
Not all drones can achieve high-altitude GPS-free positioning. Thanks to the powerful hardware and excellent algorithm support of Autel Robotics EVO II, EVO II can achieve stable positioning after losing satellite signals at altitudes below 300 meters. After losing the remote control signal, it quickly returns to the vicinity of the take-off point autonomously.
After taking off, EVO II integrates multiple sets of visual sensors to gain insight into the surrounding environment. It knows the attitude of the fuselage through the IMU, and builds a 3D map of the environment in real time to achieve precise positioning and stable flight. The flight experience is fully upgraded, making the aerial photography journey more calm.
When EVO II is suddenly interfered by strong GPS signals and loses satellite signals, the high-altitude VIO technology quickly assists the positioning of the aircraft to ensure the normal operation of aerial photography; if the source of interference is extremely strong, causing the remote control signal to be disconnected, the aircraft will immediately enter the high-altitude VIO has no GPS autonomous return status.
When the remote control signal is lost, the aircraft is continuously disturbed for more than 6s, and the high-altitude VIO has no GPS autonomous return status, which can be divided into the following situations:
During the return process, the environment 3D map constructed by multiple sets of visual sensors is used to find the ground texture features close to takeoff, and the IMU data is used for image matching to identify path planning, so that the UAV can return to the vicinity of the takeoff point. When the EVO II is out of the strong signal interference source, the GPS positioning system will intervene, and you can use the remote control to take over the aircraft, perform landing operations or fly away from the interference source.
4. Matters needing attention
High-altitude return without GPS is a safety backup function in emergency flight situations, which can help you to locate the drone after losing the GPS signal. When the ambient light is low or encounters water surfaces and large areas of repeated textures, this function will fail and positioning cannot be performed, so please fly carefully and do not rely on VIO return-to-home technology at night.
Reminder: When using drones, you should stay away from crowds, tall buildings, and no-fly areas, and fly safely and legally!