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range from a few weeks up to one and a half skills achieved in the course of the passed 22 DOCTORAL PROGRAM years. The related activities should be carried years of doctoral program are here reported: out in well known and qualified scientific ∙∙expert in computational and/or experimental IN AEROSPACE ENGINEERING institutions (universities, research centres, etc.), fluid mechanics, with capabilities to develop and well contribute to the cultural and scientific methods and models for both aerospace achievements of the research. applications and generic vehicles;

∙∙expert in active and passive control of the PhD Yearbook | 2010 Due to the amplitude and interdisciplinarity of the dynamics of aerospace structures, integrating aerospace sector, the professional skills achievable global and subsystem design; will span a wide area and not cover just a specific ∙∙expert in active and passive structural safety of 15 Chair: The aim of the course is the acquisition of the high level topic. The educational goals will create high level vehicles, both aerospace and non-aerospace; Prof. Sergio Ricci competence required to carry out innovative research and/or state specialists in the domains of: helicopters and ∙∙expert in vibration and noise control, including of the art advanced applications in industries, public or private rotary winged vehicles, fixed winged vehicles and modelling analysis, system design and research centers, Universities or public and service companies in the space vehicles. implementation of specific subsystems; area of aerospace engineering, including all the fields associated In this context, a more specific competence can ∙∙expert in the dynamics and control of aerospace to it. The level of the course allows the graduates to compete in a be gained either in a single or in the integration vehicles and related operational missions; European and international environment. of special subjects such as: dynamics and control, ∙∙expert in integrated design of complex fluid mechanics, systems and equipment, flight aerospace systems. The course is three years long, requiring 180 credit points (ECTS), mechanics, passive structural safety, intelligent Since its foundation, 23 years ago, the doctoral including possible study-abroad periods and internships in private or and automated systems, structures and materials. course on Aerospace Engineering graduated public institutions. The programmes and credits are divided in three In this respect, some examples of professional more than 60 PhDs. ENGINEERING AEROSPACE main educational areas: 1. Main courses (40 credits), during the first year: courses examining fundamental subjects (problems, theories and methods) of the scientific research in the disciplinary areas involved; DOCTORAL PROGRAM BOARD 2. Elective courses and training on specific themes (20 credits), gained in the second year: specific and personalised educational Marco Anghileri Gian Luca Ghiringhelli Sergio Ricci programs aimed at a more deep overall knowledge and to master Franco Bernelli Zazzera Michèle Lavagna Giuseppe Sala the techniques adequate for the subsequent development of the Chiara Bisagni Paolo Mantegazza Lorenzo Trainelli doctoral thesis, plus seminars focused on specific and advanced methods; Carlo Luigi Bottasso Pierangelo Masarati Luigi Vigevano 3. Development of the Doctoral Thesis (120 credits): the thesis is Luca Di Landro Teodoro Merlini developed within the Department or, in some cases, in other Luciano Galfetti Maurizio Quadrio institutions, in close contact with the Department. The thesis is started immediately (20 credits in the first year), and developed in the second (40 credits) and third year (60 credits) of the doctoral program. ADVISORY BOARD If the candidate has a background curriculum lacking some introductory knowledge required for the Doctorate, the Faculty will Paolo Apollonio (Carlo Gavazzi Space) Franco Ongaro (ESA) ask to recover such knowledge, with the assistance of the tutor. Giuseppe Bencini (SEA) Giuseppe Orsi (Agusta Westland) The same Faculty will verify afterward the overcoming of whatever was lacking during the annual meeting of admission to the second Adriano De Maio (IreR) Salvatore Sciacchitano (ENAC) year of the course. Massimo Lucchesini (AerMacchi) The course program related to point 1 does not follow a rigid scheme. So, besides widening the basic scientific culture of the candidate, it will take into consideration also the objectives and the core topics of the candidate’s thesis. Again the program outlined SCHOLARSHIP SPONSORS at points 2 and 3 will try to consider general cultural requirements as well as what is deemed to be more specifically related to thesis Agusta-Westland subject, as agreed between the candidate and the Faculty. For ASI the activities of type 2 and 3 a study period in a foreign country is allowed, even strongly suggested perhaps. Its duration should Tecnospazio 16

a gradient descent algorithm. and forced components has be On the whole, the thesis makes Biologically Inspired Control The problem of this approach proven to be effective in making the following contributions is its locality, meaning that the control problem easier in the field of grasp synthesis of Grasp-less and Grasping Tasks (particularly in high-dimensional to solve; iii) a new algorithm, control: i) a new approach input spaces) the algorithm may called Multi-sample Hierarchical to grasp synthesis has been remain stuck in a local minimum Regression, has been developed proposed and used to design

and, in general, the solution, if to mimic the functions of an a control architecture which PhD Yearbook | 2010 Franco Antonio Cavadini found, is largely dependent on associative memory, allowing the is able to grasp object of the initial guess used to start direct models learning approach arbitrary shape without using the search. For this reason, to be effectively used; iv) the a vision system; ii) the control 17 In space engineering the most Inside this context, we have development of the human a specific module has been concept of alternation between architecture has be proven to important and driving factor chosen robotic manipulation brain, the control architecture added to the architecture, the phases of waking and phases be suitable to accept adaptation in the design of hardware and as the field to which apply these developed in the thesis is based Prompter, whose task is exactly of sleep has been introduced, modules based on the software systems is the work concepts, because of the great on the construction of internal to provide an initial guess for allowing the development of a Executive Learning principles, environment, whose very interest that it has for Space direct models which are locally the solution search procedure; Meta-Learning module which specifically by implementing a constraining characteristics applications. In particular, the inverted to find the required it is based on an algorithm guarantees to obtain better Contact Controller based on have pushed the space contributions of this thesis are solution. The central principle specifically developed to mimic performance from the controller. the least squares algorithm; engineering research towards inside two specific fields: of this approach is that the the characteristics of a long-term The second part of the research iii) The effectiveness of the the study and development of i) grasp-less manipulation tasks ability to purposely interact with associative memory, the Multi- has focused on the development main principle introduced Autonomous agents. The most have been studied in the context the environment is subordinate Sample Hierarchical Regression of a control architecture for with this architecture has important feature required of Methodological learning to that of predicting its (MSHR). grasp synthesis based on the been tested and proven on ENGINEERING AEROSPACE by such a system is the ability because of the necessity to evolution. This prediction task is Moreover, taking into concept of synergy between the TWENDY-ONE robot at to dynamically change its build internal models; and ii) assigned to the modules of the consideration some studies the complexity of the hardware the Sugano Laboratory of the own behaviours based on the the Grasp synthesis problem has architecture called Propagator about the functional activities and that of the software. The Waseda University, allowing information received from the been approached developing and Anticipator: the first one of the brain during sleep, an grasp architecture is based on a to verify that the approach external world, both observing a control system which uses learns an internal representation equivalent sleeping phase has very simple work principle: the used is able to work even and interacting with it. Looking Executive Learning to adapt of the natural dynamics of been introduced: the basic finger of the hand which has with the noisy characteristics at the example provided by its behaviour to the local the environment, while the principle is to rely on this established a contact with the of a real environment; iv) the humans, it is natural to focus characteristics of the object Anticipator predicts how the ‘inactive’ phase of the system object tries to maintain fixed its performance of the controller on artificial learning in order to be grasped. presence of an interaction to analyse and revise the configuration while eventually has been extensively tested to obtain artificial autonomous The first part of this research has changes the development of experiences acquired during increasing the intensity of the using a multi-body computer agents; for the purposes of this proposed a control architecture the environment with respect the preceding operative phase exchanged force if required by simulated model of a robotic thesis we have identified three to learn how to push an to its natural evolution. The of waking, in order to organise the specific grasping situation. hand; in particular, an alternative different types of learning: object on a table without reason of this approach is that, them in a more efficient way, The adaptation of the contact way of using the rolling friction Genetic Learning, linked to previous knowledge about the separating natural dynamics while eventually extracting new forces is assigned to a control parameter has permitted the development of those problem; in this particular task and forced variations, the two important information in the module based on the concept to verify the effects of the intrinsic properties and features the generation of a control learning sub-problems are easier form of high-level dependencies of Executive Learning introduced deformability of the skin which are changed between action supposes two different to solve because of their lower between input and output earlier; the central idea is that, on the stability of a grasp. generations of individuals; decisions: i) choosing where dimensional input domains. Both variables. The group of activities when the necessity to increase Methodological Learning, to apply the force, and ii) the function approximator are executed during the sleep is the intensity of the grasp arises, which identifies and selects identifying its intensity. based on the Locally Weighted collected under the name of the torques at the joints of the knowledge useful for the From a mathematical point of Projection Regression (LWPR) Meta-Learning. the finger should be modified execution of future tasks; and view, in order to push an object algorithm. On the whole, the thesis makes in order to increase only the Executive which changes the on a plane it is necessary to As said earlier, in order to the following contributions normal component of the parameters of the system to solve an inverse problem, that is, compute the control actions in the field of grasp-less contact force; this is obtained adapt its behaviour to the knowing the desired effects the an inverse problem has to be manipulation: i) a new control thanks to the implementation specificities of the context. agent must found the actions solved, but Propagator and architecture has been proposed of the least squares algorithm The main idea at the basis which cause that behaviour in Anticipator stores internal direct and its extensive testing have to learn a simplified model of of this thesis is to study the the environment; because of models of the dynamics; for this proven its effectiveness in the relationship between the development of control systems the non single-valued nature of reason, it is necessary to look for completing the object-pushing variation of torques at joints and based on the type of learning the inverse problem and taking the desired solution through a task; ii) the decomposition of the the variation of the components processes exposed here above. into accounts studies on the sampling-based procedure like direct dynamics into its natural of the contact force. 18

in trajectories which have been in this thesis aims at merging the Lagrangian points, which Trajectory Design and Optimization designed thanks to low-thrust dynamical system theory and is useful to investigate through systems. In this perspective, it is optimal control formulation with the perspective of low energy in Highly Nonlinear Astrodynamics possible to formulate a theory a view of defining efficient and missions. As far as it concerns that may describe both low- and novel interplanetary trajectories. Earth-to-Mars transfers, three high-energy orbits, as well as The guiding principle of this different problems are solved

define transfers characterized research is the incorporation in one step: the ascending PhD Yearbook | 2010 Giorgio Pietro Mingotti by impulsive and low-thrust of low-thrust into the invariant phase from a selected parking maneuvers. Thus, the theory manifold technique, arising orbit around the Earth, the of hyperbolic passages in the from a careful analysis of the rendez-vous stage during 19 The research work developed reason why over the last few impulse has given rise to the proximity of celestial bodies restricted-three body problem. the heliocentric part of the in this thesis is to be considered decades trajectory design has development of electric engines may be reformulated by means Thanks to this perspective, it trajectory, and finally the within the boundaries of the been increasingly influenced by that can continuously offer of the invariant manifolds is possible to take advantage descending and insertion into preliminary mission analysis, optimization methods whose low values of propulsion. Thus, the same way as trajectories from both flying on low energy the target orbit around Mars. which is a key phase in space aim is the minimization of trajectory design is developed involving Lagrangian points and trajectories and from having For both the applicative mission design. It requires the the propellant necessary for a through the formulation of an low-energy transfers are usually an engine with a high value of scenarios analyzed, the Earth design of the transfer process mission. In this way, mission optimal control method for defined. specific impulse. The low-thrust escape stage is designed taking through which the spacecraft is specifications are tackled in calculating the best thrust law The aim of this research activity propulsion is introduced by explicitly advantage of a lunar taken from a given initial orbit terms of objective function which should be assigned to the is twofold. On one hand, means of attainable sets that flyby: it is possible to plan this to a specific final one thanks and restricted optimization. propulsion system. there is the exploration of are used in conjunction with event in the framework of the to a series of controls. The Following Tsiolkowsky rocket This research stems from the mathematical n-body models the exploitation of the invariant developed Moon-perturbed ENGINEERING AEROSPACE standard theoretical approach equation, the quantity of awareness that trajectories (with n≥3) through resorting manifold paths. The aim is to Sun-Earth restricted three-body to the calculation of space propellant necessary for a designed in compliance with to highly nonlinear dynamical define, through a deterministic problem, discussed in this thesis. mission transfers is known as transfer is directly proportional the principles of nonlinear systems; on the other, there is a approach, accurate first guess According to this approach, two-body problem, which is a to the energy ∆v necessary to astrodynamics, a relatively recent combination of orbits that can solutions. By means of the a significant reduction of the simplified model of the physics the transfer itself and, at the discipline whose earliest works be defined in this context by attainable sets, it is possible initial ∆v is obtained. Then, the of the problem. Following this same time, inversely proportional and relevant results date back means of a propulsive solution to describe, through the same transfers are optimized within model, during the navigation to the specific impulse of the to some ten years ago, have not characterized by continuous comprehensive theoretical wider dynamical systems, by in a celestial-body system, the propellant considered Isp. These been fully understood in some low-thrust values and high approach, ballistic trajectories, means of a direct method spacecraft is imagined to be factors have caused the scientific respects. Such an underlying specific impulses. According low-thrust arcs and invariant approach and multiple shooting under the influence of a single community to concentrate ambiguity in this discipline is to to this approach, it is possible manifolds. technique, taking also implicitly gravitational mass at a time; (especially over the last decades) be ascribed to the behaviour of to work out advantageous Two different applicative advantage of the intrinsic thus, navigation is conceived in on the development of dynamic orbits defined in n-body models, transfer solutions in terms of scenarios are investigated: a dynamics of the n- and multi- terms of a sequence of spheres models meant to illustrate with n≥3, which are governed the reduction of propellant on Planet-to-Moon transfer and an body problems. of influence. Within each of the physics of the problem by an extremely chaotic regime. board the vehicle. In addition, interplanetary transfer. In details, these spheres, the orbit of the more accurately, as well as to In addition, a systematic study of it will be possible to verify from they corresponds to the Earth- artificial satellite is influenced allow (unlike the two-body invariant manifolds - which can an engineering perspective Moon and to the Earth-Mars by the presence of one single model, which is intrinsically be explicitly analyzed through the actual opportunity for the cases. Actually, the methodology celestial body; in consequence, characterized by higher energy the evaluation of the highly exploratory spacecraft to follow proposed is suitable for any the trajectory presents all the values) the study of trajectories nonlinear intrinsic dynamics the trajectories designed in other simple transfer within the geometric features of a conic known as non-Keplerian, associated with the three-body compliance with the hypotheses solar system. In both applicative section - which is precisely which – speaking in terms of problem - has recently enabled described above. For instance, scenarios, two missions are the solution to the two-body energy - are definitely more scholars to understand the it is necessary to verify the proposed: transfers to low stable problem. Thus, whole transfers advantageous than standard leading role these manifolds physical meaning of the thrust orbits and transfers to distant involving manifold hyperbolic ones. Non-Keplerian trajectories play in space transfers. Most profiles calculated in relation unstable orbits around the passages in the proximity of are defined in n-body models, notably, these manifolds are with the possibilities made target celestial body. In details, celestial bodies may be seen in which - since the hypothesis fundamental for trajectories available by technology, such the second mission typology is as the union of different conic of Kepler’s problem is violated that, thanks to impulsive as the continuity of the control interesting for applicative and sections. - such trajectories can not be maneuvers, involve hyperbolic profile or the exposure to the theoretical purposes. Distant Spacecrafts are limited in calculated in closed form. From passages in the proximity of sunlight of solar panels during periodic orbits reveal a rich terms of propellant carried on a technological standpoint, the celestial bodies. In addition, the navigation. phase portrait, similar to the board the vehicle: this is the pursuit of high values of specific these manifolds play a key role The methodology elaborated one of periodic orbits around 20

Smart Structures in Instrumentation for Astronomy PhD Yearbook | 2010 Marco Riva

21 This Thesis Work examine easily conformable to curved parametric optical performance panel metrology. deformable mirrors. The (active alignment of optical the possible porting of smart surfaces. On the other hand, predictions of a smart The simplified modeling best compromise obtained elements, ...). structures into the design and Shape Memory Alloys (SMA) are Piezocomposites and/or SMA technique developed for with the material considered The replica technology construction of next generation materials able to recover their based substrate applicable to piezo-composites has been manifests a maximum focusing developed, even if not fully Instrumentation for Astronomy. original shape, after an external deformable mirrors. The figures validated and implemented range of 2.15 mm which compliant in terms of overall Composite Materials are deformation, if heated above of merit taken into account are into complex structures. The is quite low respect to the surface errors, can be fully currently of relatively common a characteristic temperature. the active variation of the mirror results are very interesting better MFC performances. decoupled from the actuator use in Ground-based and If the recovery of the shape is focal length and the image although obtained through In this case the limitation is embedding techniques. Local specially Space-Borne completely or partially prevented quality. In addition a sliding light models. The investigation caused by the material’s phase surface errors have been Astronomical Instrumentation. by the presence of constraints, mode based control system for of this methodology completed transition characteristics. The investigated: micro-roughness However the application of the material can generate the strongly non-linear SMA by the Raytracing computation performances obtained, even and fiber print through. The ENGINEERING AEROSPACE smart structures is very limited recovery stress. actuators has been developed provided good results in terms if not completely satisfying for most useful coating technique, and in the specific area of of efficiency of mirror’s shape activated Optics has never variations respect to the image been studied in spite of the quality. Therefore this simple large number of potential technology can easily deploy applications. In order to focalize spherical panels able to modify the work the methodology their focal position of ±1,3mm. selected of this thesis is based on The limitation is given by the the definition of a benchmark dimensions of actuators and application: a spherical mirror maximum tension applicable. of high surface quality with Future developments can surely deformable curvature. Aspects improve those limits. such as the specific smart The modeling strategy actuator to use, the embedding developed for SMA-based smart 1. Deformable mirror actuated 2. Deformable mirror actuated 3. Curvature radius variation for different lamination sequence technology and the optical- by piezo-composite actuators by SMA wires actuators structures adopt the lighter with SMA (left) and Piezo (right) actuators quality replica process needed Turner model can for preliminary to manufacture the mirror have performance prediction been treated in this work . The thesis has investigated the with numerical examples. like maximum deformed SMA smart optical devices, which is spray coating, matches Different technologies can be technological processes required Finally an optical quality surface. The lightness of this are very interesting for other with real shape and dimension considered to design smart for the adoption of those replica process for carbon modeling technique helps in application of SMA-based smart applications. The print through structures, in this work we have actuators into smart structures fiber reinforced plastic has the optimization process. The structures, like optical supports mitigation can be sufficiently considered piezo-composites and some possible modeling been analyzed as a separate more detailed Lagoudas model and actuated devices. Finally achieved with a double curing and shape-memory alloys based approaches to the actuators subsystem. This procedure can be used as a verification the sliding mode based control process that a-posteriori fills actuators. Most of the limitation behaviour prediction taking into has no influence onto the of the stress induced onto system has demonstrated that the gap with liquid resin. This of traditional piezoceramcis account trade-offs between manufacturing techniques actuators and the variations of this control strategy can be technology, even if with the low can be dealt adopting detailed analysis and overall developed for smart structures the transition temperatures. efficiently adopted to manage performances replicae, can be piezocomposite actuators that performance prediction as a because it is related to the This procedures integrated active devices based on SMA, fully employed in minor space join piezoelectric performances function of the computational mandrel surface and its into the combined optical and in particular in the case of step based astronomical applications. of piezo-ceramic fibres to the time. It has been developed a preparation. All the phases of mechanical analysis has shown activation (shutter, slit polymer matrix making the combined Finite Element and the process has been addressed, the partial applicability of SMA carriages, ...) but also with whole system more flexible and Raytracing analysis devoted to a starting from mandrel set up to technology to CFRPbased respect to sinusoidal response 22

NEW MATERIALS AND TECHNOLOGIES FOR GROUND-BASED TELESCOPES: SOLUTIONS AND TECHNOLOGICAL FEASIBILITY PhD Yearbook | 2010 Matteo Tintori

23 The work presented is observations comparable with second material was developed focused on the new materials, the satellite based ones by first with the investigation technologies and their compensating the effect of the of a proper geometry of the introduction in the ground- atmospheric turbulence. The backplate and then investigating based astronomical engineering image quality of a telescope its thermo-mechanical behavior. for the big telescopes. The depends on the level of the The design with this kind introduction of these materials turbulence corrections, which of materials is not so trivial in the space applications in relies on the accuracy of the especially for complex 3D general and also for the space physical motions of the optical shapes, so different designs have astronomy, had a big impact, but surface that performs the been developed: a standard for the ground-based telescopes compensation. An adaptive honeycomb solution and two ENGINEERING AEROSPACE their use was not considered telescopes optics system other more complex geometry because the use of traditional is usually composed by an solutions. The final choice is 1. 3D of the E-ELT, courtesy of ESO 2. The adaptive unit for E-ELT, 2. Carbon fiber composite materials and technologies Adaptive mirror, a Control unit fallen on geometry solution courtesy of ADS International prototype developed and tested has given all the benefits and reconstructor, a Wavefront used for the SiC material that for the carbon fiber composite required. Nowadays, with the sensor and a Deformable mirror foresee a diamond shaped cell have been investigated and incoming of a new generation unit whose main components honeycomb structure. With this tested too. The numerical results of telescopes with increased are a thin and deformable option it is possible to exchange agree with the mechanical and dimensions and performances, mirror, a series of high frequency the two material in the M4AU thermal tests on the prototype these new technologies have actuators, a series of sensors design without any impact with a maximum error of about a fundamental role for the coupled to the actuators, a on the other subsystems and 15% on the sagitta and 10% feasibility and functionality reference body for the sensors interfaces. on the temperatures. The of these systems. The study (or Backplate), a structure on A carbon fiber prototype has thermal and mechanical analysis of the thermo-mechanical which are mounted actuators been developed to better has also shown that a 2D model characteristics of new innovative and electronics and a structure investigate all the technological can be adequate to achieve the materials and their applicative for the macro-positioning. and engineering aspects and specifications with a low amount technologies is focused to The best architecture for the to obtain a feedback on the of error. found solutions, strategies and M4AU reference body and its reliability of the developed methodologies adequately subsystems has been studied in numerical tools, to study the dealing the needs of the new detail. Two different materials influences of the uncertainties generation of ground-based have been investigated: SiC and of the composite manufacturing telescopes. The E-ELT (European carbon fiber composites. The like the dimensions, the Extremely Large Telescope) case position of System Engineer lamination sequence,... on the was taken as a representative taken allowed to have a final unit and to highlight the and important workbench. collaboration with ADS Int. possible anomalies due to the In particular one of the main in the frame of the M4AU chosen technological solution. technological issue for the preliminary design project The analysis done has shown the E-ELT is represented by its forth where it was possible to study feasibility of both the solutions adaptive deformable mirror in detail the solution with the and the achievement of the unit (M4AU). Adaptive Optics first selected material and realize specifications on the reference techniques allow to obtain some prototypes and tests. The body. The most important ground-based astronomical study of the solution with the technological solution aspects