Nonlinear control of a tethered UAV: The taut cable case

• Published in: Automatica (Oxford) Vol. 78; pp. 174 - 184
• Main Authors: Nicotra, Marco M., Naldi, Roberto, Garone, Emanuele
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2017
• Subjects: Constrained control; Stability of nonlinear systems; Unmanned aerial vehicles; Stability of nonlinear systems; Constrained control; Unmanned aerial vehicles
• ISSN: 0005-1098; 1873-2836
• DOI: 10.1016/j.automatica.2016.12.018

This paper focuses on the design of a stabilizing control law for an aerial vehicle physically connected to a ground station by means of a tether cable. By taking advantage of the tensile force acting along the taut cable, it is shown that the tethered UAV can maintain a non-zero attitude while hovering in a constant position. The control objective is to stabilize the desired configuration while simultaneously ensuring that the cable remains taut at all times. This leads to a nonlinear control problem subject to constraints. This paper provides a two-step solution. First, the system is stabilized using a cascade control scheme based on thrust vectoring. Then, constraint satisfaction is guaranteed using a novel Reference Governor scheme.