Multiprocessor System Dedicated to Multi-Rotor Mini-UAV Capable of 3D   flying
  The paper describes an electronic multiprocessor system that assures functionality of a miniature UAV capable of 3D flying. The apparatus consists of six independently controlled brushless DC motors, each having a propeller attached to it. Since the brushless motor requires complex algorithms in order to achieve maximum torque, efficiency and response time a DSP must be used. All the motors are then controlled by a main microprocessor which is capable of reading sensors (Inertial Measurement Unit (IMU)-orientation and GPS), receiving input commands (remote controller or trajectory plan) and sending independent commands to each of the six motors. The apparatus contains a total of eight microcontrollers: the main unit, the IMU mathematical processor and one microcontroller for each of the six brushless DC motors. Applications for such an apparatus could include not only military, but also search-and-rescue, geodetics, aerial photography and aerial assistance. 
Adrian-Ioan Lita, Ioan Plotog, Lidia Dobrescu
cs.CE