Navigation technology of UAV

It is almost similar to the philosophical question of "where to come from and where to go" for the UAV to know exactly where to go, which is an unavoidable problem at any development stage of the UAV.

1. Positioning technology

(1)GPS carrier phase positioning

At present, the research projects in this field are: Piksi； developed by SwiftNavigaTIon Company; RTKLIB open source project developed by Tokyo Ocean University, Japan.

(2) Multi-information source positioning

BAE, the British military, recently announced the positioning technology they developed called NAVSOP. This technology will make use of information including TV, radio, Wi-Fi and so on to make up for the shortage of GPS.

(3)UWB(UltraWideband) wireless positioning.

2. Velocity measurement technology

At present, it is recognized that the more accurate speed measurement scheme is the fusion of "vision (optical flow)+ultrasonic+inertial navigation". AR.Drone is the first multi-rotor aircraft to adopt this technology, which greatly improves the maneuverability of the aircraft and has achieved great success.

The PX4 Autopilot Open Source Project provides an open source optical flow sensor PX4Flow. The sensor can help multi-rotor hover accurately without GPS. Wu, Phantom3 and Phantom4 introduced by DJI Company also adopted this technology.

3. Obstacle avoidance technology

It is an important step to make the flying UAV "long glasses" to identify obstacles on the flight path and fly or hover accurately. In the future, UAV obstacle avoidance technology will achieve breakthroughs in these aspects:

(1) depth camera obstacle avoidance technology;

(2) Obstacle avoidance technology of sonar system;

(3) "Vision+Memristor" obstacle avoidance technology;

(4) binocular vision obstacle avoidance technology;

(5) Small electronic scanning radar;

(6) Laser scanning ranging radar;

(7) Four-dimensional radar.

4. Tracking technology

Identify the target and follow the flight, reduce the user's operating burden, and can use the drone to perform special tasks under special environmental conditions. Intelligent tracking mainly includes:

(1)GPS tracking;

(2) Visual tracking.

At present, these technologies have been reflected in DJI Phantom4 and other advanced models.