A Model-Based Oscillation Suppression Approach for a Cable-Suspended Dual-Arm Aerial Manipulator

Abstract

In aerial manipulators, the presence of cables between the aerial platform and the articulated system is beneficial to increase the distance between rotors' blades and the obstacles in the workspace and absorb unavoidable impacts arising during the interaction with the environment. However, cables also produce pendulum-like oscillatory behaviour due to dynamic coupling and to the effect of external forces when the robot navigates in free space through the environment. This paper presents a model-based control approach for the suppression of oscillations in cable-suspended dual-arm aerial manipulators. Contrary to many oscillation suppression techniques that act on the suspension platform, we exploit the dynamics of the articulated system to achieve the same goal. A linear controller is devised applying a partial feedback linearization technique for the unactuated variables of our system, i.e. the cables. Simulation and experimental tests are carried out using a quadrotor equipped with a cable-suspended dual-arm system to validate our proposed framework. With our control technique, drone-induced oscillations were reduced by up to 89%, with a settling time of 2.5 seconds.