Coordinate-Free Dynamics and Differential Flatness of a Class of 6DOF Aerial Manipulators

Abstract

In this work, we derive a coordinate-free formulation of the coupled dynamics of a class of 6DOF aerial manipulators consisting of an underactuated quadrotor equipped with a 2DOF articulated manipulator, and demonstrate that the system is differentially flat with respect to the end effector pose. In particular, we require the center of mass of the entire system to be fixed in the end effector frame, suggesting a reasonable mechanical design criterion. We make use of an inertial decoupling transformation to demonstrate differential flatness, allowing us to plan dynamically feasible trajectories for the system in the space of the 6DOF pose of the end effector, which is ideal for achieving precise manipulator tasks. Simulation results validate the flatness-based planning methodology for our dynamic model, and its usefulness is demonstrated in a simulated aerial videography task.