Hard Real-Time Implementation of a Nonlinear Controller for the Quadrotor Helicopter

A hard real-time implementation on a single processor of a nonlinear controller for trajectory tracking of the quadrotor helicopter is presented. An inertial measurement unit and an Optitrack positioning system provide the necessary state measurements. The nonlinear controller has been previously published, so that, this paper focuses on the details of its onboard implementation. In particular, we propose a hard real-time algorithm, a method to identify the aerodynamic characteristics of the actuators and a procedure to tune the nonlinear control gains. Flying tests are presented to illustrate the performance of the quadrotor closed loop dynamics.