Attitude and Tension Control of a Tethered Formation of Aerial Vehicles

In this thesis we deal with the problem of formation control exploiting external constraints. In particular, we want to tether two quadrotors to each other and to a fixed point by ropes. Then, we want to control the quadrotors in order to drive the orientation of the formation, keeping the cables tautopenEmbargo per motivi di segretezza e/o di proprietà dei risultati e/o informazioni sensibil

Entre l'abandon et les traces résilientes aux montagnes territoriales d'Orobie (Bergame)

[CA] Aquest article forma part d'un projecte d'investigació més ampli, l'objectiu de la qual és explorar mètodes i estratègies multiescalars (des de l'escala territorial a l'edilícia) i enfocaments multidisciplinaris per a recuperar àrees infrautilitzades a les muntanyes del nord d'Itàlia. Durant dècades, aquests territoris han patit una alta incidència de fenòmens d'abandó a causa de la seua proximitat a les àrees metropolitanes, la qual cosa ha provocat la pèrdua de cures i un augment de la fragilitat territorial. No obstant això, són rics en significats culturals que s'expressen en l'estreta relació entre paisatges naturals i antropogeografies. En aquest marc, el valor identitari és un element essencial per a la protecció i la cura dels mateixos territoris i com a eina de planificació per a establir la resiliència d'aquests. Aquest treball pretén centrar-se en la zona de les Terres Altes de Bèrgam, que són llocs complexos en estar quasi prop dels centres urbans de Milà, que són zones considerades marginals en termes de lògica més àmplia. De fet, en els últims anys, el massís Orobic ha sigut un dels principals objectes d'explotació industrial i turística (anys 60-80), abans de patir fenòmens d'abandó que han obligat i continuen espentant a aquestes zones a una important reconsideració. En aquesta direcció, l'article assenyala quins són els punts més crítics a tindre en compte per al renaixement d'aquestes muntanyes oblidades.[EN] This paper is part of a broader research project, which aims to explore multi-scale methods and strategies (from territorial to building scale) and multidisciplinary approaches to recover underused areas in the mountains of Northern Italy. For decades, these territories have suffered from high incidences of abandonment phenomena due to their proximity to metropolitan areas, leading to loss of care and an increase in territorial fragility. Nevertheless, they are rich in cultural meaning expressed it s in the close relationship between natural and anthropogeographical landscapes. In this framework, identity value is an essential element for the protection and care of the territories themselves and as a planning tool to establish the resilience of these territories. This paper aims to focus on the area of the Highlands of Bergamo, which are complex places since they are almost close to the urban center of Milan, but are areas considered marginal in terms of wider logic. In fact, in the past years, the Orobic massif has been one of the main objects of industrial and tourist exploitation (the 1960s-80s), before suffering from abandonment phenomena that have forced and continue to push these areas to the point of major reconsideration. In this direction, the paper points out which are the most critical points to consider for the rebirth of these neglected mountains.[ES] Este artículo forma parte de un proyecto de investigación más amplio, cuyo objetivo es explorar métodos y estrategias multiescalares (desde la escala territorial a la edilicia) y enfoques multidisciplinares para recuperar áreas infrautilizadas en las montañas del norte de Italia. Durante décadas, estos territorios han sufrido una alta incidencia de fenómenos de abandono debido a su proximidad a las áreas metropolitanas, lo que ha provocado la pérdida de cuidados y un aumento de la fragilidad territorial. Sin embargo, son ricos en significados culturales que se expresan en la estrecha relación entre paisajes naturales y antropogeográficos. En este marco, el valor identitario es un elemento esencial para la protección y el cuidado de los propios territorios y como herramienta de planificación para establecer la resiliencia de los mismos. Este trabajo pretende centrarse en la zona de las Tierras Altas de Bérgamo, que son lugares complejos al estar relativamente cerca del centro urban de Milán, pero que son zonas consideradas marginales en términos de lógica más amplia. De hecho, en los últimos años, el macizo Orobico ha sido uno de los principales objetos de explotación industrial y turística (años 60-80), antes de sufrir fenómenos de abandono que han obligado y siguen empujando a estas zonas a una importante reconsideración. En esta dirección, el artículo señala cuáles son los puntos más críticos a tener en cuenta para el renacimiento de estas montañas olvidadas.[FR] Cet article fait partie d un projet de recherche plus large, dont l objectif est d explorer des méthodes et des stratégies multiscalaires (depuis l échelle territoriale jusqu au bâtiment), ainsi que des approches multidisciplinaires afin de récupérer des zones sous-utilisées aux montagnes du nord de l Italie. Pendant des décennies, ces territoires ont souffert une forte incidence de phénomènes d abandon à cause de leur proximité aux zones métropolitaines, ce qui a entraîné la perte de soins et une augmentation de leur fragilité territoriale. Cependant, ils sont riches en signifiés culturels qui s expriment dans le rapport étroit entre paysages naturels et anthropogeógraphies. Dans ce contexte, la valeur identitaire est un élément essentiel pour la protection et le soin de ces territoires, ainsi qu un outil de planification pour établir leur résilience. Ce travail cherche à se concentrer sur la zone des Hautes Terres de Bergame, des endroits complexes étant donnée leur proximité du centre urbain de Milan : des zones considérées marginales en termes de logique plus large. En fait, pendant les dernières années, le massif Oropic a été un des principaux objets d exploitation industrielle et touristique (années 60-80), avant de subir des phénomènes d abandon obligeant encore aujourd hui ces zones à une reconsidération importante. Dans ce sens, cet article signale les points les plus critiques à considérer pour la renaissance de ces montagnes oubliées.La investigació pertany al projecte de “Territorial Fragility” en poder de DAStU (Departament d’Arquitectura i Estudis Urbans – Politecnico di Milano), finançat pel Ministeri d’Universitat i Recerca (MIUR) per a 2018-2022 com a part de la iniciativa Departaments d’Excel·lència (Llei núm. 232/2016).Tognon, A.; Bovati, M. (2022). Entre l'abandonament i les empentes resilients a les muntanyes territorials d'Orobie (Bèrgam). ANUARI d Arquitectura i Societat. (2):86-110. https://doi.org/10.4995/anuari.2022.1870486110

Equilibria, Stability, and Sensitivity for the Aerial Suspended Beam Robotic System subject to Parameter Uncertainty

This work studies how parametric uncertainties affect the cooperative manipulation of a cable-suspended beam-shaped load by means of two aerial robots not explicitly communicating with each other. In particular, the work sheds light on the impact of the uncertain knowledge of the model parameters available to an established communication-less force-based controller. First, we find the closed-loop equilibrium configurations in the presence of the aforementioned uncertainties, and then we study their stability. Hence, we show the fundamental role played in the robustness of the load attitude control by the internal force induced in the manipulated object by non-vertical cables. Furthermore, we formally study the sensitivity of the attitude error to such parametric variations, and we provide a method to act on the load position error in the presence of the uncertainties. Eventually, we validate the results through an extensive set of numerical tests in a realistic simulation environment including underactuated aerial vehicles and sagging-prone cables, and through hardware experiments

Equilibria, Stability, and Sensitivity for the Aerial Suspended Beam Robotic System subject to Parameter Uncertainty

This work studies how parametric uncertainties affect the cooperative manipulation of a cable-suspended beam-shaped load by means of two aerial robots not explicitly communicating with each other. In particular, the work sheds light on the impact of the uncertain knowledge of the model parameters available to an established communication-less force-based controller. First, we find the closed-loop equilibrium configurations in the presence of the aforementioned uncertainties, and then we study their stability. Hence, we show the fundamental role played in the robustness of the load attitude control by the internal force induced in the manipulated object by non-vertical cables. Furthermore, we formally study the sensitivity of the attitude error to such parametric variations, and we provide a method to act on the load position error in the presence of the uncertainties. Eventually, we validate the results through an extensive set of numerical tests in a realistic simulation environment including underactuated aerial vehicles and sagging-prone cables, and through hardware experiments

Control of over-redundant cooperative manipulation via sampled communication

In this work we consider the problem of mobile robots that need to manipulate/transport an object via cables or robotic arms. We consider the scenario where the number of manipulating robots is redundant, i.e. a desired object configuration can be obtained by different configurations of the robots. The objective of this work is to show that communication can be used to implement cooperative local feedback controllers in the robots to improve disturbance rejection and reduce structural stress in the object. In particular we consider the realistic scenario where measurements are sampled and transmitted over wireless, and the sampling period is comparable with the system dynamics time constants. We first propose a kinematic model which is consistent with the overall systems dynamics under high-gain control and then we provide sufficient conditions for the exponential stability and monotonic decrease of the configuration error under different norms. Finally, we test the proposed controllers on the full dynamical systems showing the benefit of local communication

Learning to Open Doors with an Aerial Manipulator

The field of aerial manipulation has seen rapid advances, transitioning from push-and-slide tasks to interaction with articulated objects. So far, when more complex actions are performed, the motion trajectory is usually handcrafted or a result of online optimization methods like Model Predictive Control (MPC) or Model Predictive Path Integral (MPPI) control. However, these methods rely on heuristics or model simplifications to efficiently run on onboard hardware, producing results in acceptable amounts of time. Moreover, they can be sensitive to disturbances and differences between the real environment and its simulated counterpart. In this work, we propose a Reinforcement Learning (RL) approach to learn motion behaviors for a manipulation task while producing policies that are robust to disturbances and modeling errors. Specifically, we train a policy to perform a door-opening task with an Omnidirectional Micro Aerial Vehicle (OMAV). The policy is trained in a physics simulator and experiments are presented both in simulation and running onboard the real platform, investigating the simulation to real world transfer. We compare our method against a state-of-the-art MPPI solution, showing a considerable increase in robustness and speed