Modelling, Analysis and Control of OmniMorph: an Omnidirectional Morphing Multi-rotor UAV

This paper introduces for the first time the design, modelling, and control of a novel morphing multi-rotor Unmanned Aerial Vehicle (UAV) that we call the OmniMorph. The morphing ability allows the selection of the configuration that optimizes energy consumption while ensuring the needed maneuverability for the required task. The most energy-efficient uni-directional thrust (UDT) configuration can be used, e.g., during standard point-to-point displacements. Fully-actuated (FA) and omnidirectional (OD) configurations can be instead used for full pose tracking, such as, e.g., constant attitude horizontal motions and full rotations on the spot, and for full wrench 6D interaction control and 6D disturbance rejection. Morphing is obtained using a single servomotor, allowing possible minimization of weight, costs, and maintenance complexity. The actuation properties are studied, and an optimal controller that compromises between performance and control effort is proposed and validated in realistic simulations

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

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

Modelling, Analysis and Control of OmniMorph:an Omnidirectional Morphing Multi-rotor UAV

We present the design, modelling, and control of a novel morphing multi-rotor Unmanned Aerial Vehicle (UAV) that we call the OmniMorph. The morphing ability allows the platform to switch between different configurations to achieve the required task. The uni-directional thrust (UDT) configuration can be used for energy-efficient navigation, while fully-actuated (FA) and omnidirectional (OD) configurations can be used for full pose tracking and make the platform assume any orientation while compensating the gravity. The platform is equipped with eight bi-directional propellers that are actively tilted in a synchronized fashion using only one additional degree of actuation

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

International audienceIn this paper 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 po-sition/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

Physical Human-Aerial Robot Interaction and Collaboration: Exploratory Results and Lessons Learned

International audienceIn this work, we present, a first of its kind, physical human-aerial robot interaction (pHARI) experiment, with an articulated aerial manipulator (AM). The robotic platform is a fully-actuated multi-rotor aerial vehicle (MRAV) with fixedly-tilted propellers endowed with a 3degree of freedom (DoF) robotic arm. We implemented a state-of-the-art control architecture composed of a feedback linearization motion controller, an admittance filter and a hybrid wrench observer. The experiments prove the viability of a new use case in aerial robotics, namely pHARI. The experimental results also shed light on the limitations of the current state-of-the-art and provide insights into possible research directions. The video of the experiments, which is available at https://youtu.be/LrQxXbQ5IHc, shows an experiment simulating work at height, where a human manually guides an AM and then attaches a tool to its end effector (EE)

Towards a Flying Assistant Paradigm: the OTHex

International audienceThis 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

Design of Multirotor Aerial Vehicles: A Taxonomy Based on Input Allocation

International audienceThis 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 aerial vehicles and their designs, 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 mechanical designs. Finally, we provide a discussion on the common traits of the designs found in the literature and the main open and future problems

Physical Human-Aerial Robot Interaction and Collaboration: Exploratory Results and Lessons Learned

International audienceIn this work, we present, a first of its kind, physical human-aerial robot interaction (pHARI) experiment, with an articulated aerial manipulator (AM). The robotic platform is a fully-actuated multi-rotor aerial vehicle (MRAV) with fixedly-tilted propellers endowed with a 3degree of freedom (DoF) robotic arm. We implemented a state-of-the-art control architecture composed of a feedback linearization motion controller, an admittance filter and a hybrid wrench observer. The experiments prove the viability of a new use case in aerial robotics, namely pHARI. The experimental results also shed light on the limitations of the current state-of-the-art and provide insights into possible research directions. The video of the experiments, which is available at https://youtu.be/LrQxXbQ5IHc, shows an experiment simulating work at height, where a human manually guides an AM and then attaches a tool to its end effector (EE)

Physical Human-Aerial Robot Interaction and Collaboration: Exploratory Results and Lessons Learned

In this work, we present, a first of its kind, physical human-aerial robot interaction (pHARI) experiment, with an articulated aerial manipulator (AM). The robotic platform is a fully-actuated multi-rotor aerial vehicle (MRAV) with fixedly-tilted propellers endowed with a 3degree of freedom (DoF) robotic arm. We implemented a state-of-the-art control architecture composed of a feedback linearization motion controller, an admittance filter and a hybrid wrench observer. The experiments prove the viability of a new use case in aerial robotics, namely pHARI. The experimental results also shed light on the limitations of the current state-of-the-art and provide insights into possible research directions. The video of the experiments, which is available at https://youtu.be/LrQxXbQ5IHc, shows an experiment simulating work at height, where a human manually guides an AM and then attaches a tool to its end effector (EE)

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

International audienceWe 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 multi-rotor 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