Extending the maneuverability of multirotors promises to yield a considerable increase in their scope of applications, such as carrying out more challenging inspection tasks and generating complex, uninterrupted movements of an attached camera. In this article, we address the promise of multirotor maneuverability by presenting Voliro, a novel aerial platform that combines the advantages of existing multirotor systems with the agility of vehicles having omniorientational controllability. In other words, Voliro can fly in any direction while maintaining an arbitrary orientation.

The Voliro Omniorientational Hexacopter: An Agile and Maneuverable Tiltable-Rotor Aerial Vehicle

We present the design, motion planning, and control of an aerial manipulator for non-trivial physical interaction tasks, such as pushing while sliding on curved surfaces—a task which is motivated by the increasing interest in autonomous non-destructive tests for industrial plants. The proposed aerial manipulator consists of a multidirectional-thrust aerial vehicle—to enhance physical interaction capabilities—endowed with a 2-DoFs lightweight arm—to enlarge its workspace. This combination makes it a truly-redundant manipulator going beyond standard aerial manipulators based on collinear multirotor platforms. The controller is based on a PID method with a “displaced” positional part that ensures asymptotic stability despite the arm elasticity. A kinodynamic task-constrained and control-aware global motion planner is used. Experiments show that the proposed aerial manipulator system, equipped with an Eddy current probe, is able to scan a metallic pipe sliding the sensor over its surface and preserving the contact. From the measures, a weld on the pipe is successfully detected and mapped.

/pdf/a-truly-redundant-aerial-manipulator-system-with-application-5fxp5kduky.pdf

A Truly-Redundant Aerial Manipulator System With Application to Push-and-Slide Inspection in Industrial Plants

Expected to operate in the imminent future, air taxi service (ATS) is an aerial on-demand transport for a single passenger or a small group of riders, which seeks to transform the method of everyday commute. This uncharted territory in the emerging transportation world is anticipated to enable consumers bypass traffic congestion in urban road networks. By adopting an electric vertical takeoff and landing concept (eVTOL), air taxis could be operational from skyports retrofitted on building rooftops, thus gaining advantage from an implementation standpoint. Motivated by the potential impact of ATS, this study provides a review of air taxi systems and associated operations. We first discuss the current developments in the ATS (demand prediction, air taxi network design, and vehicle configuration). Next, we anticipate potential future challenges of ATS from an operations management perspective, and review the existing literature that could be leveraged to tackle these problems (ride-matching, pricing strategies, vehicle maintenance scheduling, and pilot training and recruitment). Finally, we detail future research opportunities in the air taxi domain.

Air taxi service for urban mobility: a critical review of recent developments, future challenges, and opportunities

This article analyzes the evolution and current trends in aerial robotic manipulation, comprising helicopters, conventional underactuated multirotors, and multidirectional thrust platforms equipped with a wide variety of robotic manipulators capable of physically interacting with the environment. It also covers cooperative aerial manipulation and interconnected actuated multibody designs. The review is completed with developments in teleoperation, perception, and planning. Finally, a new generation of aerial robotic manipulators is presented with our vision of the future. 

Past, Present, and Future of Aerial Robotic Manipulators

In the last decade, the aerial robotics community has witnessed an increased interest in fully actuated multirotor unmanned aerial vehicles (UAVs) that have more capabilities than conventional underactuated multirotors. This article collects the different UAV designs having fully actuated aerodynamic wrench generation proposed in the literature to date. The work includes a systematic derivation of the control-allocation matrix for all of the concepts as well as a discussion of the different quantitative criteria used for optimizing UAV designs.

/pdf/fully-actuated-multirotor-uavs-a-literature-review-51c150pkem.pdf

Fully Actuated Multirotor UAVs: A Literature Review

This paper reviews the effect of multirotor aerial vehicle designs on their abilities in terms of tasks and system properties. We propose a general taxonomy to characterize and describe multirotor ...

https://journals.sagepub.com/doi/pdf/10.1177/02783649211025998

Design of multirotor aerial vehicles: A taxonomy based on input allocation:

This paper presents the OTHex platform for aerial manipulation developed at LAAS-CNRS. The OTHex is probably the first multi-directional thrust platform designed to act as Flying Assistant which can aid human operators and/or Ground Manipulators to move long bars for assembly and maintenance tasks. The work emphasis is on task-driven custom design and experimental validations. The proposed control framework is built around a low-level geometric controller, and includes an external wrench estimator, an admittance filter, and a trajectory generator. This tool gives the system the necessary compliance to resist external force disturbances arising from contact with the surrounding environment or to parameter uncertainties in the load. A set of experiments validates the real-world applicability and robustness of the overall system.

/pdf/towards-a-flying-assistant-paradigm-the-othex-59cdan7wd8.pdf

Towards a Flying Assistant Paradigm: the OTHex

In this letter we present an optimization-based method for controlling aerial manipulators in physical contact with the environment. The multi-task control problem, which includes hybrid force-motion tasks, energetic tasks, and position/postural tasks, is recast as a quadratic programming problem with equality and inequality constraints, which is solved online. Thanks to this method, the aerial platform can be exploited at its best to perform the multi-objective tasks, with tunable priorities, while hard constraints such as contact maintenance, friction cones, joint limits, maximum and minimum propeller speeds are all respected. An on-board force/torque sensor mounted at the end effector is used in the feedback loop in order to cope with model inaccuracies and reject external disturbances. Real experiments with a multi-rotor platform and a multi-DoF lightweight manipulator demonstrate the applicability and effectiveness of the proposed approach in the real world.

/pdf/direct-force-feedback-control-and-online-multi-task-rsi3mf2g16.pdf

Direct Force Feedback Control and Online Multi-Task Optimization for Aerial Manipulators

This paper reviews the impact of multirotor aerial vehicles designs on their abilities in terms of tasks and system properties. We propose a general taxonomy to characterize and describe multirotor aerial vehicles and their design, which we apply exhaustively on the vast literature available. Thanks to the systematic characterization of the designs we exhibit groups of designs having the same abilities in terms of achievable tasks and system properties. In particular, we organize the literature review based on the number of atomic actuation units and we discuss global properties arising from their choice and spatial distribution in the designs. Finally, we provide a discussion on the common traits of the designs found in the literature and the main future open problems.

Quentin Sable

Papers

A Truly-Redundant Aerial Manipulator System With Application to Push-and-Slide Inspection in Industrial Plants

Design of multirotor aerial vehicles: A taxonomy based on input allocation:

Towards a Flying Assistant Paradigm: the OTHex

Direct Force Feedback Control and Online Multi-Task Optimization for Aerial Manipulators

Survey on Aerial Multirotor Design: a Taxonomy Based on Input Allocation