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.

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This work reports on the development and evaluation of an aerial system for active tool handling on remote locations. In the proposed approach a multirotor UAV is responsible for moving an end-effector with a tool to the region of interest and providing sufficient contact force for the endeffector to accomplish the desired task. The end-effector is equipped with actuated wheels that rely on the contact force to both allow an operator to re-position while in contact with the environment and perform the tool operation.Preliminary experiments validate the approach in a cleaning scenario and demonstrate the repeatability in an experiment with 18 consecutive repetitions of the approach.

This paper proposes a semi-autonomous bilateral control architecture for unmanned aerial vehicles. During autonomous navigation, a human operator is allowed to assist the autonomous controller of the vehicle by actively changing its navigation parameters to assist it in critical situations, such as navigating through narrow paths. The overall goal of the controller is to combine the stability and precision of an autonomous control with the cognitive abilities of a human operator, only when strictly required for the accomplishment of a task. The control architecture has been validated through simulations and experiments.

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