About Quadcopter

The work here presented has been done using the proven AR Drone 2.0, produced by the French company Parrot Inc. It represents a valid option for research purposes because it is very affordable ($250 USD in 2017) and it comprises multiple sensors in a unique platform. It is equipped with an external hull for indoor navigation and it is mainly piloted using smart-phones and tablets through the application released by the producer over a WiFi network. 

The specification of the UAV are as follows: 

  • Dimensions: 53 cm x 52 cm (hull included); 
  • Weight: 420 g; 
  • Inertial Measurements Units (IMU) including gyroscope, accelerometer, magnetometer, altimeter and pressure sensor; 
  • Front-camera with a High-definition (HD) resolution (1280x720), a field of view (FOV) of 73.5° x 58.5° and video streamed at 30 frame per second (fps); 
  • Bottom-camera with a Quarted Video graphics Array (QVGA) resolution (320x240), a FOV of 47.5◦ x 36.5◦ and video streamed at 60 fps; 
  • Central processing unit running an embedded version of Linux operating system; 
The downward-looking camera is mainly used to estimate the horizontal velocity and the accuracy of this estimation highly depends on the ground texture and the quad-copter's altitude. Only one of the two video streams can be streamed at the same time. Sensors data are received by a workstation at 200Hz. The on-board controller (closed-source) is used to act on the roll (Phi) and pitch (Theta), the yaw rotational speed (Psi) and the vertical velocity of the platform (dot{z}). Control commands u = (Phi, Theta, Psi, dot{z}) in [-1,1] are sent to the quad-copter at a frequency of 100Hz.