Onboard system for flight control of a small UAV

In this paper, we present the design of an autopilot embedded system applied to control a four rotor mini helicopter, called X4-flyer. The main goal is to achieve a stable flight, controlling the vehicle attitude; this is done using two control strategies: a linear PD control and nonlinear nested saturations control. The onboard system uses a simplified parallel processing architecture and the main processor performs a multitasking program to handle the data acquisition, control law computation, and actuators correction to get the desired set point. Real time experiments show that the autopilot is a platform relievable with low cost components.