Robotic manipulation of a rotating chain

This paper considers the problem of manipulating a uniformly rotating chain: the chain is rotated at a constant angular speed around a fixed axis using a robotic manipulator. Manipulation is quasi-static in the sense that transitions are slow enough for the chain to be always in "rotational" equilibrium. The curve traced by the chain in a rotating plane -- its shape function -- can be determined by a simple force analysis, yet it possesses complex multi-solutions behavior typical of non-linear systems. We prove that the configuration space of the uniformly rotating chain is homeomorphic to a two-dimensional surface embedded in $\mathbb{R}^3$. Using that representation, we devise a manipulation strategy for transiting between different rotation modes in a stable and controlled manner. We demonstrate the strategy on a physical robotic arm manipulating a rotating chain. Finally, we discuss how the ideas developed here might find fruitful applications in the study of other flexible objects, such as elastic rods or concentric tubes.Comment: 12 pages, 9 figure

A motion planning approach to 6-D manipulation with aerial towed-cable systems

Presentado al International Micro Air Vehicle Conference and Flight Competition celebrado en Toulouse (Francia) del 17 al 20 de septiembre de 2013.We propose a new approach for the reliable 6-dimensional quasi-static manipulation with aerial towed- cable systems. The novelty of this approach lies in the combination of results deriving from the static analysis of cable-driven manipulators with a cost-based motion-planning algorithm to solve manipulation queries. Such a combination of methods is able to produce feasible paths that do not approach dangerous/uncontrollable configurations of the system. As part of our approach, we also propose an original system that we name the FlyCrane. It consists of a platform attached to three flying robots using six fixed-length cables. Results of simulations on 6-D quasi-static manipulation problems show the interest of the method.This work has been partially supported by the Spanish Ministry of Economy and Competitiveness under contract DPI2010-18449, by the European Community under contract ICT 287617 “ARCAS”, and by a Juan de la Cierva contract supporting the first author.Peer Reviewe

6-D manipulation with aerial towed-cable system

We propose a new approach for the reliable 6-dimensional quasi-static manipulation of an aerial towed-cable system. The novelty of this approach lies in the combination of results deriving from the static analysis of cable-driven manipulators with the application of a cost-based motion-planning algorithm to solve manipulation queries. Using this approach, we can ensure that the produced paths are feasible and do not approach dangerous configurations that could provoque the malfunction of the system. The approach has been simulated on the FlyCrane, consisting of a platform attached to three flying robots using six fixed-length cables. The obtained results show the success and the suitability of the approach.Postprint (author’s final draft

Wrench Capability Analysis of Aerial Cable Towed Systems

International audienceAerial cable towed systems (ACTSs) can be created by joining unmanned aerial vehicles (UAVs) to a payload to extend the capabilities of the system beyond those of an individual UAV. This paper describes a systematic method of evaluating the avail- able wrench set and the robustness of equilibrium of ACTSs by adapting wrench analysis techniques used in cable-driven parallel robots to account for the constraints of quadrotor actuation. Case studies are provided to demonstrate the analysis of different classes of ACTSs, as a means of evaluating the design and operating configurations

Motion planning with dynamics awareness for long reach manipulation in aerial robotic systems with two arms

Human activities in maintenance of industrial plants pose elevated risks as well as significant costs due to the required shutdowns of the facility. An aerial robotic system with two arms for long reach manipulation in cluttered environments is presented to alleviate these constraints. The system consists of a multirotor with a long bar extension that incorporates a lightweight dual arm in the tip. This configuration allows aerial manipulation tasks even in hard-to-reach places. The objective of this work is the development of planning strategies to move the aerial robotic system with two arms for long reach manipulation in a safe and efficient way for both navigation and manipulation tasks. The motion planning problem is addressed considering jointly the aerial platform and the dual arm in order to achieve wider operating conditions. Since there exists a strong dynamical coupling between the multirotor and the dual arm, safety in obstacle avoidance will be assured by introducing dynamics awareness in the operation of the planner. On the other hand, the limited maneuverability of the system emphasizes the importance of energy and time efficiency in the generated trajectories. Accordingly, an adapted version of the optimal Rapidly-exploring Random Tree algorithm has been employed to guarantee their optimality. The resulting motion planning strategy has been evaluated through simulation in two realistic industrial scenarios, a riveting application and a chimney repairing task. To this end, the dynamics of the aerial robotic system with two arms for long reach manipulation has been properly modeled, and a distributed control scheme has been derived to complete the test bed. The satisfactory results of the simulations are presented as a first validation of the proposed approach.Unión Europea H2020-644271Ministerio de Ciencia, Innovación y Universidades DPI2014-59383-C2-1-

Hybrid Modeling of Deformable Linear Objects for Their Cooperative Transportation by Teams of Quadrotors

his paper deals with the control of a team of unmanned air vehicles (UAVs), specifically quadrotors, for which their mission is the transportation of a deformable linear object (DLO), i.e., a cable, hose or similar object in quasi-stationary state, while cruising towards destination. Such missions have strong industrial applications in the transportation of hoses or power cables to specific locations, such as the emergency power or water supply in hazard situations such as fires or earthquake damaged structures. This control must be robust to withstand strong and sudden wind disturbances and remain stable after aggressive maneuvers, i.e., sharp changes of direction or acceleration. To cope with these, we have previously developed the online adaptation of the proportional derivative (PD) controllers of the quadrotors thrusters, implemented by a fuzzy logic rule system that experienced adaptation by a stochastic gradient rule. However, sagging conditions appearing when the transporting drones are too close or too far away induce singularities in the DLO catenary models, breaking apart the control system. The paper’s main contribution is the formulation of the hybrid selective model of the DLO sections as either catenaries or parabolas, which allows us to overcome these sagging conditions. We provide the specific decision rule to shift between DLO models. Simulation results demonstrate the performance of the proposed approach under stringent conditions.This work has been partially supported by spanish MICIN project PID2020-116346GB-I00, and project KK-2021/00070 of the Elkartek 2021 funding program of the Basque Government. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 777720

Differential-Flatness and Control of Quadrotor(s) with a Payload Suspended through Flexible Cable(s)

We present the coordinate-free dynamics of three different quadrotor systems : (a) single quadrotor with a point-mass payload suspended through a flexible cable; (b) multiple quadrotors with a shared point-mass payload suspended through flexible cables; and (c) multiple quadrotors with a shared rigid-body payload suspended through flexible cables. We model the flexible cable(s) as a finite series of links with spherical joints with mass concentrated at the end of each link. The resulting systems are thus high-dimensional with high degree-of-underactuation. For each of these systems, we show that the dynamics are differentially-flat, enabling planning of dynamically feasible trajectories. For the single quadrotor with a point-mass payload suspended through a flexible cable with five links (16 degrees-of-freedom and 12 degrees-of-underactuation), we use the coordinate-free dynamics to develop a geometric variation-based linearized equations of motion about a desired trajectory. We show that a finite-horizon linear quadratic regulator can be used to track a desired trajectory with a relatively large region of attraction

A study to identify and compare airborne systems for in-situ measurements of launch vehicle effluents

An in-situ system for monitoring the concentration of HCl, CO, CO2, and Al2O3 in the cloud of reaction products that form as a result of a launch of solid propellant launch vehicle is studied. A wide array of instrumentation and platforms are reviewed to yield the recommended system. An airborne system suited to monitoring pollution concentrations over urban areas for the purpose of calibrating remote sensors is then selected using a similar methodology to yield the optimal configuration