Research Projects

Autonomous control of Unmanned Aerial Vehicles (UAVs) enables several critical applications in National defence, Military reconnaissance, civilian search and rescue, and industrial maintenance, besides scientific space and deep-sea exploration. However, there are several technical challenges that need to be addressed in order to achieve autonomous flight, especially with small fixed-wing UAVs. One of the most important among the challenges is ensuring a globally stable autopilot that can recover from arbitrarily large deviations from a nominal trajectory on account of environmental disturbances in the form of atomospheric gusts and turbulence. State-of-art autopilots use Proportional-Integral-Derivative (PID) controllers to pilot the vehicle for small deviations from the nominal trajectory, and switch to safe modes upon experiencing large deviations from there. The switching control is however associated with performance losses, in order the avoid the destabilizing effects of the ensuing discontinuous control signals. In this research, we propose to use a smooth nonlinear controller that provides global stability against large deviations, and also estimates quasi-static components in the external disturbances.