Pose and position trajectory tracking for aerial transportation of a rod-like object

Abstract

This paper focuses on a pose tracking problem for a system composed of two connected rigid bodies, namely an aerial vehicle – with hovering capabilities – and a rod-like rigid body. The rod-like rigid body has an axis of axial symmetry, and the joint connecting the aerial vehicle and the rod lies along that axis. The aerial vehicle is meant to transport that object, which can swing/slung with respect to the vehicle: we refer to this as generalized slung load transportation because the object being transported is a rod-like object, as opposed to standard slung load transportation where the object is a point mass with no moment of inertia. Given this system, we consider two tracking problems. Firstly, we assume that a torque input on the joint is available, and, for this scenario, we formulate a semi-pose tracking problem, requiring the rod object to track a desired pose trajectory, apart from rotations around its axis of axial symmetry (and thus the semi qualifier). Secondly, we assume that no such torque input is available, and, for this scenario, we formulate a position tracking problem, requiring a specific point along the axis of axial symmetry of the rod object to track a desired position trajectory. Our approach for solving both these problems lies in finding a state and an input transformations, such that the vector field in the new coordinates is of a known form for which controllers are found in the literature, and which we leverage in this paper. Simulations are presented that validate the proposed algorithms.