Application of substantial and sustained force to vertical surfaces using a quadrotor

Abstract

In the field of aerial robotics, one of the key challenges is to enable aerial manipulators to exert substantial forces on the environment. Enabling this will allow the technology to perform meaningful tasks airborne, such as cleaning or grinding surfaces. While in contact and applying a large, continuous force, control of the UAV's attitude is a challenge. In this work, we show that a regular (PID-based) attitude controller is incapable of stabilizing aerial manipulators that apply physical contact forces on the environment that are comparable to the UAV's weight. We present a novel control algorithm that uses an LQR-optimized state feedback on the roll and yaw angle while in contact. Experiments on a UAV of 1.5 kg show that the proposed controller is capable of applying a contact force of over 15 N-equal to the UAV's weightsustained for several minutes.

The AEROARMS Project: Aerial Robots with Advanced Manipulation Capabilities for Inspection and Maintenance

“…In AEROWORKS (http://www.aeroworks2020.eu/) collaborative exploration, aerial manipulation, and also estimation, localization and control of UAVs are included. Aerial Manipulation has been also demonstrated indoors [11].…”

Nonlinear Model Predictive Control for the Stabilization of a Wheeled Unmanned Aerial Vehicle on a Pipe

“…The impacts may also be absorbed through a passive vacuum-cup technology as in [2]. The problem of carrying out large forces in contact with the environment with an underactuated drone is instead investigated in [3] through the use of LQRoptimized state feedback on the roll and yaw angle. In case the inspections measurements are performed in a crowded and narrow environment, and the drone is too bulky to stay close to the surface to be inspected, a long reach aerial manipulator can be employed [4].…”

Multimodal Aerial Locomotion: An Approach to Active Tool Handling

“…This introduces disturbances in the form of forces applied to the tip of the manipulator, which results in a rotation and displacement of the aerial system. To deal with this undesired effect, we propose to use a modified controller that is based on our previous work [2]. This contact controller stabilizes the relative orientation of the multirotor to the end-effector from disturbances caused by the coupling with the end-effector, which results in automatic tracking of the ground locomotion.…”

“…These challenges are even more problematic when the aerial platform is underactuated, as is the vast majority of commercially available aerial platforms. For this class of systems the dynamics are altered in interaction due to contact constraints, which introduces additional coupling terms between the linear and rotational dynamics [2]. This, in combination with the anisotropy of the torque-limits, complicates the task of both applying relevant contact force and moving the end-effector on the surface.…”

“…Three actuated omnidirectional wheels are placed on this end-effector to allow active locomotion of the tool, which require sufficient friction with the surface to function correctly. To guarantee this friction, a controller based on our previous work [2] is applied. The scope of this controller is twofold: it provides the contact force that is necessary to ensure wheeled locomotion and tool operation, and it stabilizes the attitude of the UAV subject to the interaction forces.…”