  Bilateral teleoperation of an aerial manipulator facilitates the execution of
industrial missions thanks to the combination of the aerial platform's
maneuverability and the ability to conduct complex tasks with human
supervision. Heretofore, research on such operations has focused on flying
without any physical interaction or exerting a pushing force on a contact
surface that does not involve abrupt changes in the interaction force. In this
paper, we propose a human reaction time compensating haptic-based bilateral
teleoperation strategy for an aerial manipulator extracting a wedged object
from a static structure (i.e., plug-pulling), which incurs an abrupt decrease
in the interaction force and causes additional difficulty for an aerial
platform. A haptic device composed of a 4-degree-of-freedom robotic arm and a
gripper is made for the teleoperation of aerial wedged object-extracting tasks,
and a haptic-based teleoperation method to execute the aerial manipulator by
the haptic device is introduced. We detect the extraction of the object by the
estimation of the external force exerted on the aerial manipulator and generate
reference trajectories for both the aerial manipulator and the haptic device
after the extraction. As an example of the extraction of a wedged object, we
conduct comparative plug-pulling experiments with a quadrotor-based aerial
manipulator. The results validate that the proposed bilateral teleoperation
method reduces the overshoot in the aerial manipulator's position and ensures
fast recovery to its initial position after extracting the wedged object.
