Improving hovering performance of tethered unmanned helicopters with nonlinear control strategies

Abstract

Abstract-Hovering capabilities of unmanned helicopters can be seriously affected by wind effects. One possible solution for improving hovering performance under such circumstances is the use of a tethered setup that takes advantage of the tension exerted on the cable that links the helicopter to the ground. This paper presents a more elaborated strategy for helicopter control in this augmented setup that extends previous work on the subject by the authors. Particularly, a combination of classical PID control laws together with model inversion blocks constitutes the base of the new controller. Additionally, feed-forward action for counteracting rotational couplings is also accounted for. The resulting nonlinear control structure considers the complex and nonlinear nature of the tethered system in a better way. Several demonstrating simulations under artificially generated wind influences are presented to endorse the validity of the new proposed controller