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Design and Simulation of Multilevel Interacting Mobile Robots for Space and Industrial Applications
No full textWhen studying and planning to use mobile robots that need to be deployed in any application scenario, these robots are always subjected to different kind of interactions. These can be classified into three major groups: interactions between robots and their surroundings, interactions between the robot and other robotic devices, and interactions between robots and humans. Therefore, it becomes necessary, in the study and design phase, to take into account, study, model, and address these interactions to achieve proper and optimal performance of the robot, and to to avoid unpleasant situations.
In this dissertation, the interactions occurring on deployed mobile robots are addressed in different contexts. Specifically, this dissertation is divided into two main declinations: mobile robotics for space applications and for the industrial settings. Finally, with a focus on robot interactions, considerable attention is placed on the development of methods needed to address and solve them.
The main achievements obtained for the space applications field are the control of vehicles for space exploration in exotic applications, e.g. manipulation of objects via towing, and the study of the dynamics of complex robotic systems, e.g. articulated planetary rovers and landers. For the industrial settings field, instead, are the development of a framework for the synthesis of a fleet manager that controls a fleet of tethered robots, and the setup of a framework for the development of smart controllers for mobile robots navigating moving crowds.
This dissertation is structured into four major chapters. The first provides an introduction to mobile robotics from a very general point of view, along with a classification of the various types of interactions that occur on robots. An overview of the use of mobile robots in the two macro fields of application considered, in general, is also provided, along with the problems and challenges characteristic of each of these fields. Finally, it provides a brief overview of the methodology and tools that will be used in subsequent chapters.
The second chapter focuses on the development and application of mobile robots in the context of space mobile robotics. The problem of soft-landing of an innovative robotic lander for space exploration is presented. Next, an innovative prototype named Archimede, of a four-wheel steerable rover is featured. Its design includes a suspension system, which ensures higher operational speeds. Moreover, every single aspect and component of the rover is first described, followed by a focus on steering capability and impact dissipation. The interaction between the wheels and the ground is then studied. Finally, it proposes a detailed study on a technique for manipulating ground-resting loads, i.e. towing through elastic elements. In this context, the employment of this technique on the Archimede rover is studied and validated.
The third focuses on the development and application of mobile robots in the field of industrial mobile robotics. A problem characterised by robot-environment and robot-robot interactions is first addressed. Specifically, a multi-robot problem is considered where individual robots are chained together with cables, to meet the existing demands of a specific industrial context. Therefore, a high-level controller is presented, which assumes the role of the fleet-manager using techniques specific to redundant manipulators. This system aims to manage the fleet while allowing robots to perform tasks. Next, one kind of human-robot interaction is presented, i.e. the problem of navigating a mobile robot through a moving crowd. Specifically, the controller of the mobile robot is based on artificial neural networks, and trained in appropriate simulation environments using Reinforcement Learning techniques. The performance of the controller is then validated numerically and experimentally.
The fourth and final chapter reports the conclusions of this dissertation work.When studying and planning to use mobile robots that need to be deployed in any application scenario, these robots are always subjected to different kind of interactions. These can be classified into three major groups: interactions between robots and their surroundings, interactions between the robot and other robotic devices, and interactions between robots and humans. Therefore, it becomes necessary, in the study and design phase, to take into account, study, model, and address these interactions to achieve proper and optimal performance of the robot, and to to avoid unpleasant situations.
In this dissertation, the interactions occurring on deployed mobile robots are addressed in different contexts. Specifically, this dissertation is divided into two main declinations: mobile robotics for space applications and for the industrial settings. Finally, with a focus on robot interactions, considerable attention is placed on the development of methods needed to address and solve them.
The main achievements obtained for the space applications field are the control of vehicles for space exploration in exotic applications, e.g. manipulation of objects via towing, and the study of the dynamics of complex robotic systems, e.g. articulated planetary rovers and landers. For the industrial settings field, instead, are the development of a framework for the synthesis of a fleet manager that controls a fleet of tethered robots, and the setup of a framework for the development of smart controllers for mobile robots navigating moving crowds.
This dissertation is structured into four major chapters. The first provides an introduction to mobile robotics from a very general point of view, along with a classification of the various types of interactions that occur on robots. An overview of the use of mobile robots in the two macro fields of application considered, in general, is also provided, along with the problems and challenges characteristic of each of these fields. Finally, it provides a brief overview of the methodology and tools that will be used in subsequent chapters.
The second chapter focuses on the development and application of mobile robots in the context of space mobile robotics. The problem of soft-landing of an innovative robotic lander for space exploration is presented. Next, an innovative prototype named Archimede, of a four-wheel steerable rover is featured. Its design includes a suspension system, which ensures higher operational speeds. Moreover, every single aspect and component of the rover is first described, followed by a focus on steering capability and impact dissipation. The interaction between the wheels and the ground is then studied. Finally, it proposes a detailed study on a technique for manipulating ground-resting loads, i.e. towing through elastic elements. In this context, the employment of this technique on the Archimede rover is studied and validated.
The third focuses on the development and application of mobile robots in the field of industrial mobile robotics. A problem characterised by robot-environment and robot-robot interactions is first addressed. Specifically, a multi-robot problem is considered where individual robots are chained together with cables, to meet the existing demands of a specific industrial context. Therefore, a high-level controller is presented, which assumes the role of the fleet-manager using techniques specific to redundant manipulators. This system aims to manage the fleet while allowing robots to perform tasks. Next, one kind of human-robot interaction is presented, i.e. the problem of navigating a mobile robot through a moving crowd. Specifically, the controller of the mobile robot is based on artificial neural networks, and trained in appropriate simulation environments using Reinforcement Learning techniques. The performance of the controller is then validated numerically and experimentally.
The fourth and final chapter reports the conclusions of this dissertation work
OPTIMIZATION OF THE PRODUCTION PROCESS OF DERMATOPHAGOIDES SPP. MITES AND OF ITS ALLERGENS
No full textQuesta tesi è frutto della collaborazione tra l'Università e Lofarma S.p.A., un’azienda farmaceutica italiana leader nel settore che produce preparati per pazienti allergici come kit diagnostici e immunoterapie. A tale scopo nel reparto di Acarologia ogni anno vengono allevati e raccolti decine di chilogrammi di acari adulti e, dopo alcune manipolazioni, utilizzati nel reparto produttivo come materia prima per la maggior parte delle formulazioni. Lo scopo di questo progetto è analizzare l'attuale metodo di produzione e studiare se alcuni passaggi potrebbero essere ottimizzati per migliorare la resa, il tasso di produzione e la qualità della materia prima, cercando nel contempo di ridurre costi e tempi di lavorazione.
La ricerca è stata suddivisa in 2 aree principali: 1) Procedure di Allevamento (valutazione della qualità della dieta e del ceppo allevato) e 2) Manipolazioni della Materia Prima (ottimizzazione del processo di pulizia e valorizzazione della materia prima). Tra questi, i risultati più significativi sono stati raggiunti nella sezione Manipolazione delle Materie Prime, dove viene descritto un nuovo processo di rifinitura in grado di ottenere rese finali più elevate in tempistiche più brevi.
Dopo aver analizzato l'intero ciclo produttivo, è possibile concludere che, nel contesto del Reparto di Acarologia, è più conveniente procedere con una migliore manipolazione della materia prima piuttosto che modificare le attuali metodiche di allevamento, che sembrano già adatte per le esigenze di Lofarma.This thesis is based on collaboration between University and Lofarma S.p.A., a leading Italian pharmaceutical company which produce preparation for allergic patients like diagnostic kits and immunotherapies. To this purpose every year dozens of kilograms of adult mites are reared and collected in the Acarology department and, after manipulations, used in the Production Department as raw material for most of the preparation. The aim of this project is to analyze the current production methodology of Acarology department and investigate if some steps could be optimized to improve the yield, the production rate and the quality of the raw material while trying to reduce costs and processing times.
The research has been divided in 2 main areas: 1) Rearing Procedures (quality assessment about the diet and the strain enacted) and 2) Raw Material Manipulations (optimization of the refining process and valorization of the Raw Material). Between those, most significant results have been achieved in the Raw Material Manipulation section, where is described a novel refining process capable of obtaining higher final yields in a shorter working time.
After analyzing the whole manufacturing cycle, is possible to conclude that, within the context of the Acarology Department, is more convenient to proceed with a better manipulation of the raw material in the refining process rather than modifying the actual rearing procedure, which is already suitable for Lofarma needs
Towing an Object With a Rover
No full textThe present study investigates the problem of towing an object that is lying on a surface in a given workspace and the applicability to a planetary rover with four steering wheels. A quasi-static method has been introduced and used for path planning and for the synthesis of both object and rover trajectories. The rover uses a tether as the towing medium, which is modeled as an elastic unilateral constraint. Moreover, a kinematic model of the rover that includes steering asymmetrical joint limits is taken into account. The dynamics model of the overall system is then derived, and a sensitivity analysis is performed over a finite number of different trajectories, in order to evaluate the quasi-static assumption, the effects of the model, and the influence of the elastic constraint. Finally, experiments have been performed using the novel Archimede rover prototype and compared with dynamics simulations; the remarkable adherence shown with the model validates the overall approach
Design and multi-body dynamic analysis of the Archimede space exploration rover
Full text linkIn this work we present the novel planetary rover prototype ‘‘Archimede’’. The rover is a four wheel steering
vehicle where each wheel is connected to the chassis by means of an articulated leg. These also act as a
suspension system, exploiting the function of complex elastic joints named S-Structures, a series of preloaded
components constituting the elastic joints. These aggregates have shown to be capable of providing compliance
to otherwise stiff structures. The Kane’s method is used to derive an analytical model for the dynamics of
the rover, treated as a multi-body system. In the model we implement a lumped-parameters model for the
S-Structure as a revolute joint with an applied non-linear torque. The soil is modeled as a rigid body and the
wheel–soil interaction follows the Kelvin–Voigt model. The analytical model is validated numerically – via
comparison with MSC Adams simulation software – in case of ground impact and obstacle negotiation; the
experimental validation is performed on ground impact tests with a Motion Amplification high speed camera
and dedicated image processing software. Results show good adherence between the models, thus validating
the approach
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
On the Modelling of Tethered Mobile Robots as Redundant Manipulators
Full text linkControlling a chain of tethered mobile robots (TMRs) can be a challenging task. This kind of system can be considered kinematically as an open-chain robotic arm where the mobile robots are considered as a revolute joint and the tether is considered as a variable length link, using a prismatic joint. Thus, the TMRs problem is decoupled into two parallel problems: the equivalent robotic manipulator control and the tether shape computation. Kinematic redundancy is exploited in order to coordinate the motion of all mobile robots forming the chain, expressing the constraints acting on the mobile robots as secondary tasks for the equivalent robotic arm. Implementation in the Gazebo simulation environment shows that the methodology is capable of controlling the chain of TMRs in cluttered environments
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dynamic Modeling and Simulation of a Robotic Lander Based on Variable Radius Drums
Full text linkSoft-landing on planetary surfaces is the main challenge in most space exploration missions.
In this work, the dynamic modeling and simulation of a three-legged robotic lander based on variable
radius drums are presented. In particular, the proposed robotic system consists of a non-reversible
mechanism that allows a landing object to constant decelerate in the phase of impact with ground.
The mechanism is based on variable radius drums, which are used to shape the elastic response of a
spring to produce a specific behavior. A dynamic model of the proposed robotic lander is first presented.
Then, its behavior is evaluated through numerical multibody simulations. Results show the feasibility of
the proposed design and applicability of the mechanism in landing operations
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