This paper introduces a novel constraint in the master joystick workspace, termed the dynamic kinesthetic boundary, that aids a pilot to navigate an aerial robotic vehicle through a cluttered environment. The proposed approach exploits spatial cues by projecting the remote environment into a hard boundary in the master device workspace that provides a pilot with a natural representation of approaching obstacles. The approach is distinguished from classical force feedback approaches by allowing normal operation of the vehicle in free flight and only imposing constraints when approaching and interacting with the environment. A key advantage is that contact with the environment constraint is immediately perceptible to a pilot, allowing them to make suitable adjustments to their inputs. Modulation of the velocity reference for the slave robot ensures obstacle avoidance while allowing a vehicle to approach as close as desired to an object, albeit at a slow speed. A comprehensive user study was performed to systematically test the proposed algorithm and comparisons to two existing state-of-the-art approaches are provided to demonstrate the relative performance of the proposed approach.

Force feedback is a powerful sensory cue that can provide a user, remotely teleoperating a vertical takeoff and landing (VTOL) aerial robotic vehicle, with an enhanced perception of the robot motion and interaction with the local environment. The accepted framework for mobile vehicle teleoperation, inspired by decades of research into manipulator teleoperation, maps joystick displacements to vehicle velocity set points and reflects interactive forces from the vehicle to the human operator. This paper proposes a novel admittance configured haptic interface where the force input from the user is used as a velocity set point and the joystick position is servo-controlled to reflect the vehicle velocity. This paper provides a comparative study, both analytic and experimental, of the two interfaces to investigate the performance and perceptual differences in the context of teleoperation of a VTOL aerial robot.

We consider the problem in which a supervisor or remote pilot provides a real-time linear velocity reference to a multirotor aerial robot, either through a traditional remote control handset, a modern haptic interface, or semi-autonomous guidance control system. In all such cases, the goal is to servo-control the vehicle's velocity to the set point as quickly and as efficiently as possible. The challenge is to achieve this robustly in the presence of unknown wind disturbances and in situations in which the vehicle moves into global position system (GPS) denied environments (indoors, urban canyons, forests) where estimation of the vehicle's velocity is challenging. These situations include unclutterred environments, poor visibility environments caused by poor lighting, and poorly textured visual environments where laser- and vision-based sensors become unreliable. The approach taken is to develop a coupled nonlinear complementary velocity aided attitude filter that provides estimates of both the inertial and body-fixed frame linear velocities, as well as the attitude of a multirotor aerial vehicle, that functions effectively even when only the inertial measurement unit and barometric sensor measurements are available. When full inertial velocity measurements are available (from GPS, Vicon, or a vision system), the filter additionally estimates the external wind speed. In this paper, we formally present the proposed filter along with experimental results and a comparison of the filter to recent results in the literature and in situations in which inertial reference frame velocities are available intermittently. The proposed filter is computationally simple to implement, easy to calibrate and tune, and provides an excellent base level functionality for modern multirotor aerial robotic systems that will be required to function robustly in a variety of environments.

This paper describes the theory and practice for a stable haptic teleoperation of a flying vehicle. It extends passivity-based control framework for haptic teleoperation of aerial vehicles in the longest intercontinental setting that presents great challenges. The practicality of the control architecture has been shown in maneuvering and obstacle-avoidance tasks over the internet with the presence of significant time-varying delays and packet losses. Experimental results are presented for teleoperation of a slave quadrotor in Australia from a master station in the Netherlands. The results show that the remote operator is able to safely maneuver the flying vehicle through a structure using haptic feedback of the state of the slave and the perceived obstacles.

This paper considers the question of providing effective feedback of vehicle dynamic forces to a pilot in haptic teleoperation of aerial robots. We claim that the usual state-of-the-art haptic interface, based on research motivated by robotic manipulator slaves and virtual haptic environments, does a poor job of reflecting dynamic forces of a mobile robotic vehicle to the user. This leads us to propose a novel force feedback user interface for mobile robotic vehicles with dynamics. An analysis of the closed-loop force-displacement transfer functions experienced by the master joystick for the classical and the new approach clearly indicate the advantages of the proposed formulation. Both the classical and the proposed approach have been implemented in the teleoperation of a quadrotor vehicle and we present quantitative and cognitive performance data from a user study that corroborates the expected performance advantages.