Design, Implementation and Analysis of a Controller for a Load Suspended From an Aerial Vehicle

Sammanfattning: In this work, a trajectory tracking controller structure for a systemcomposed of a load and an aerial vehicle, which are connected by a rope, is presented. The main goal is to design a controller that guarantees that the load tracks a desired trajectory asymptotically. The load is modeled as a point mass while the aerial vehicle is assumed to be fully actuated. The load and the aerial vehicle are connected via a ropelike structure of fixed length that can only withstand tensile forces along itsorientation. This system can be transformed into a form that resembles the form of systems used to describe underactuated aerial vehicles. A backstepping procedure is used to design a nonlinear control law whichis based on a controller for a double integrator. A bounded controllaw for double integrators is developed such that the position of the load converges to the desired trajectory for initial positions that are arbitrarily far away from the desired trajectory. The proposed controller structure has been verified both in simulations and with experiments using quadcopters at the Smart Mobility Lab at KTH.