Cellular materials are characterized by a complex interconnected structure of struts or plates and shells which make up the cells edges and faces. Their structure can be advantageously engineered in order to tailor their properties according to the specific application. This aspect makes them particularly attractive for the manufacturing of bone prosthetics since, compared to traditional fully dense implants, although more complex to produce and with less predictable properties, implants with a highly porous structure can be manufactured to match the bone stiffness and at the same time favor bone ingrowth and regeneration. The development of Selective Laser Melting (SLM) made possible to obtain metallic cellular materials with highly complex structures characterized by a wide range of cell morphologies that allow to finely tune the mechanical properties of the implant to the patient needs. Titanium alloys such as Ti-6Al-4V have shown excellent biocompatibility combined with good mechanical properties and have also been successfully used in the manufacturing of lattice structures with minute details via SLM. Nevertheless, there are still several issues to consider. For instance, despite the static mechanical properties of such lattices being addressed by many studies, the fatigue behavior still remains little investigated, even though it is a critical aspect in load-bearing biomedical implants (consider, for example, the periodic nature of human gait in the case of hip implants). In this regard, increasing the fatigue resistance of cellular lattices by finely adjusting the geometry, for instance by adding fillets at the cell-wall joints, is a new interesting opportunity made possible by additive manufacturing technologies. On the other hand, a discrepancy between the as-designed and the as-built geometry in SLM parts is an issue that can be critically important for lattices with pore size and strut thicknesses of a few hundred microns, such as biomedical lattices. Indeed, any geometrical imperfection introduces a degree of uncertainty that can alter the mechanical properties of the as-built lattice. This work represents an attempt in the direction of building a deeper understanding of the effect of the fine geometrical details, such as the fillet radius at the joints and the thickness of the struts, on the elastic constants and on the fatigue resistance of Ti-6Al-4V SLM lattices, with the aim to develop analytical predictive models of the mechanical properties. Moreover, this work also aims at investigating the as-built/as-designed morphological discrepancy in lattices in relation to the their as-designed geometry and its effects on the elastic modulus and the fatigue resistance. In this regard, the purpose is to develop quantitative relationships between the as-designed and the as-built geometry in order to obtain design tools to predict the final morphology of the lattice by taking into account the manufacturing errors. This thesis covers a wide range of topics, therefore, in the interest of a better presentation, the results of the research have been devided into three independent Chapters. Each of them has been provided of an abstract and an Introduction and divided into a Materials and Methods (or Modelling) section, a Results and Discussion section and finally Conclusions and References. Naturally, the chapters are logically connected and coherent with the frame defined by the title of the thesis. Therefore, this thesis is organized into five chapters. In the first Chapter the backrground to the topics discussed in the subsequent chapters is provided and the relevant literature is reviewed, while in the fifth and last Chapter some conclusions are drawn, and future perspectives are discussed. The core of the work is contained in the three central chapters. In Chapter II, analytical models developed to predict the elastic constants and the stress concentration factors (SCF) of 2D lattices with variously arranged square cells and filleted junctions are presented. The effect of stretching and bending actions on the elastic constants of a single cell is identified by devising an analytical model based on classical beam theory and and periodic boundary conditions. Specifically, two spatial arrangements are considered: a honeycomb with regular square cells and a honeycomb with square cells staggered by a prescribed offset of half of the cell wall length. The theoretical beam model is fitted to the results of a 2D Finite Elements (FE) model based on plane elements via an extensive parametric analysis. In this way, semi-analytical formulas are proposed to calculate the stiffness in large domains of the geometric parameters (strut thickness t0 and fillet radius R). A numerical method is also proposed to estimate the SCFs at the cell wall junctions of a 2D regular square cellular lattice. The aim is to obtain a model capable of calculating the values of the SCF as a function of the unit cell geometrical parameters and consequently assess the stress state in the lattice, which is one of the main factors determining fatigue resistance. This was achieved by applying the FE method to the unit cell for wide intervals of t0 and R to calculate the SCF for each couple of the parameters. The values of the SCFs were then fitted with functions. The models developed in this Chapter are then used in the subsequent chapters as a support in the design of 3D regular square lattices and in the interpretation of the mechanical characterization. In Chapter III, the results of the mechanical and morphological characterization of different regular cubic open-cell cellular structures produced via SLM of Ti-6Al-4V alloy, all with the same nominal elastic modulus of 3 GPa that matches that of human trabecular bone, are presented. The fully reversed fatigue strength at 106 cycles and the elastic modulus were measured and an attempt was made to link them to the manufacturing defects (porosity and geometrical inaccuracies). Half of the specimens was subjected to a stress relief thermal treatment while the other half to Hot Isostatic Pressing (HIP), and the effect of the treatments on porosity and on the mechanical properties was assessed. The results of fatigue and quasi-static tests on regular cubic lattices were compared with FE calculations based on the as-designed geometry and on the as-built geometry reconstructed from micro X-ray computed tomography (ÂμCT) scans. It was observed that the fatigue strength and, to a lesser extent, the elastic modulus are correlated with the number and severity of defects and that predictions on the mechanical properties based on the as-designed geometry are not accurate. The fatigue strength seems to be highly dependent on the surface irregularities and on the notches introduced during the manufacturing process. In fully reversed fatigue tests, the high performances of stretching dominated structures compared to bending dominated structures are not found. In fact, with thicker struts, such structures proved to be more resistant, even if bending actions were present. Given the small size of the unit cells (the unit cell size is 1.5 mm and the strut thickness is 0.26 mm) and the limitations in accuracy of the printer, the fillet radii at the junctions were highly irregular and somewhat hard to recognize. In order to investigate the real benefit of filleted junctions on the stress concentration effects at the junctions and to assess the manufacturability of such minute geometrical detail, a new experimental campaign was set up. In Chapter IV, a set of cubic lattice specimens with filleted junctions was designed and produced via SLM. The size of the unit cell is considerably larger than that of the previous specimens, being 8 mm, 6 mm and 4 mm with the rest of the geometrical parameters scaled accordingly. Thus, nine combinations of the geometrical parameters of the unit cell and three orientations with respect to the printing direction are considered. The aim is to investigate the relationship between the as-designed and the as-built geometry and to find the smallest radius which can be accurately reproduced by the printer. Moreover, a compensation strategy of the morphological defects is devised using the mathematical relationships obtained between the as-designed and the as-built strut thickness. This strategy consists in modifying the input CAD to compensate for the deviations introduced by the SLM process.

Gravitational waves, which are ripples in space-time predicted by Einstein's General Theory of Relativity, have revolutionized our understanding of the universe since their first-ever direct detection in 2015 by the Advanced Laser Interferometer Gravitational Wave Observatory (Advanced LIGO), the most sensitive on-ground gravitational wave detector ever built. The detection of gravitational waves marked a monumental milestone in scientific achievement, providing a new observational tool to probe some of the most enigmatic phenomena in the universe. The successful detection of gravitational waves has not only validated Einstein's theory but has also opened a new window onto the universe, allowing scientists to explore phenomena that were previously hidden from traditional electromagnetic observations. Moreover, gravitational wave astronomy promises to shed light on fundamental questions regarding the nature of gravity, the origin of compact objects, and the evolution of the universe itself. However, the on-ground detection of gravitational waves is affected by some factors limiting the measurement sensitivity, mainly the presence of a relatively high background noise due to the Earth environment. As a result, innovative technologies to detect gravitational waves from space are being developed, since the outer space environment is less noisy compared to Earth. The inaugural space-based detector, known as the Laser Interferometer Space Antenna (LISA), is being developed and its launch is currently scheduled for 2034. Given the mission complexity, a dedicated precursory mission known as LISA Pathfinder (LPF) was launched in 2015 and operated until 2017. LISA Pathfinder aimed at demonstrating the feasibility of gravitational waves detection directly from space by measuring the noise affecting the relative acceleration of two free falling test masses (TMs) enclosed in the same spacecraft. The scientific goal of the mission was fulfilled, proving that a requirement on the TMs relative acceleration 10 times more demanding than the one set was met. The mission was a scientific success, however some difficulties had to be faced, particularly during the release of the TMs into free fall. The mission telemetry data shows that, for the majority of the in-flight releases, all linear and rotational TMs velocity components were not compliant with the requirements. Given these anomalies, an additional dedicated TMs release campaign was carried out at the end of the mission phase to test different release strategies. The analysis of the extended mission campaign telemetry data supports the hypothesis that the separation of the mechanism responsible for the TM release from the TM caused the TMs to assume unexpected states. The research work outlined in the thesis arises in this context: understanding what happened at the TMs releases is critical since the mechanism in charge of the release will also be employed in LISA. Starting from three extensive on-ground experimental campaigns, through a methodical exploration of the campaigns results, the TM release into free fall function is assessed, providing guidelines for the design of the release mechanism units for LISA. The factors contributing to the momentum acquired by the TMs at the release are identified and analyzed, demonstrating that the nominal release dynamics is compliant with the LPF design requirements. The results are considered for possible application in future space missions relying on very accurate precision sensors or accelerometers for spacecraft navigation and scientific measurements study.

L'attività di ricerca descritta in questa tesi fornisce linee guida per la progettazione di arti protesici inferiori, con particolare riferimento alla progettazione di protesi a basso costo. La necessità di efficienti protesi a basso costo risulta infatti sentita nei Paesi in via di sviluppo ma anche dalle fasce meno abbienti dei paesi occidentali. Al fine di comprendere le strategie adottate dall'apparato locomotorio per muoversi con le protesi sono analizzati il cammino fisiologico, le protesi presenti sul mercato ed infine le modalità con cui le loro prestazioni sono valutate. Con il presente lavoro, dopo aver osservato la presenza di una scarsa strutturazione della metodologia di progettazione che riguarda specialmente il settore del basso costo, si propone una metodologia il più possibile oggettiva e ripetibile tesa ad individuare quali sono gli aspetti essenziali di una protesi per garantire al paziente una buona qualità di vita. Solo questi aspetti dovranno essere selezionati al fine di ottenere la massima semplificazione della protesi e ridurre il più possibile i costi. Per la simulazione delle attività di locomozione, in particolare del cammino, è stato elaborato un apposito modello spaziale del cammino. Il modello proposto ha 7 membri rigidi (corrispondenti a piedi, tibie, femori e bacino) e 24 gradi di libertà. Le articolazioni e l'appoggio dei piedi al suolo sono modellati con giunti sferici. La pianta del piede consente tre possibili punti di appoggio. I criteri di realizzazione delle simulazioni possono comprendere aspetti energetici, cinematici e dinamici considerati come obiettivo dall'apparato locomotorio. In questa tesi vengono trattati in particolare gli aspetti cinematici ed è mostrata un'applicazione della procedura nella quale vengono dapprima identificati i riferimenti fisiologici del cammino e quindi simulato il cammino in presenza di una menomazione al ginocchio (eliminazione della flessione in fase di appoggio). Viene quindi lasciato a sviluppi futuri il completamento della procedura e la sua implementazione in un codice di calcolo. / Inexpensive and efficient prostheses are needed both for developing and Western countries. The research activity described in this thesis aims at providing guidelines for the development of lower limb prostheses, referring in particular to the design of low cost prostheses. Physiological gait, commercial prostheses and prostheses evaluation methods are analyzed in order to understand the strategies adopted by the human locomotion system to walk with such artificial devices. This work outlines a lack of systematic approaches for the design prostheses, in particular for the low cost ones. This lack is overcome by suggesting a metodology, which is as much objective and repeatable as possible, oriented to the definition of the essential aspects that provide the patient with a good quality of life. Only these aspects should be selected to design the low cost prostheses, i.e. in order to obtain the maximum simplification and thus the maximum cost reduction. A model for the simulation of gait has been implemented. The spatial model presented is made up of 7 rigid members (correspondent to feet, shanks, thighs and pelvis) and has 24 degrees of freedom. The articular joints and the contact of the foot with ground are modeled as spherical joints. The foot sole allows three different supporting points. The simulations are executed utilizing criteria that consider the energetic, kinematic and dynamic issues as addressed by the locomotion system. An application of the procedure is shown. The identification of the kinematic physiological parameters and the simulation of a maimed gait (without stance knee flexion) are presented.

Il rapido progresso della tecnologia, lo sviluppo di prodotti altamente sofisticati, la forte competizione globale e l’aumento delle aspettative dei clienti hanno messo nuove pressioni sui produttori per garantire la commercializzazione di beni caratterizzati da una qualità sempre crescente. Sono gli stessi clienti che da anni si aspettano di trovare sul mercato prodotti contraddistinti da un livello estremo di affidabilità e sicurezza. Tutti siamo consapevoli della necessità per un prodotto di essere quanto più sicuro ed affidabile possibile; ma, nonostante siano passati oramai 30 anni di studi e ricerche, quando cerchiamo di quantificare ingegneristicamente queste caratteristiche riconducibili genericamente al termine qualità, oppure quando vogliamo provare a calcolare i benefici concreti che l’attenzione a questi fattori quali affidabilità e sicurezza producono su un business, allora le discordanze restano forti. E le discordanze restano evidenti anche quando si tratta di definire quali siano gli “strumenti più idonei” da utilizzare per migliorare l’affidabilità e la sicurezza di un prodotto o processo. Sebbene lo stato dell’arte internazionale proponga un numero significativo di metodologie per il miglioramento della qualità, tutte in continuo perfezionamento, tuttavia molti di questi strumenti della “Total Quality” non sono concretamente applicabili nella maggior parte delle realtà industriale da noi incontrate. La non applicabilità di queste tecniche non riguarda solo la dimensione più limitata delle aziende italiane rispetto a quelle americane e giapponesi dove sono nati e stati sviluppati questi strumenti, oppure alla poca possibilità di effettuare investimenti massicci in R&D, ma è collegata anche alla difficoltà che una azienda italiana avrebbe di sfruttare opportunamente i risultati sui propri territori e propri mercati. Questo lavoro si propone di sviluppare una metodologia semplice e organica per stimare i livelli di affidabilità e di sicurezza raggiunti dai sistemi produttivi e dai prodotti industriali. Si pone inoltre di andare al di là del semplice sviluppo di una metodologia teorica, per quanto rigorosa e completa, ma di applicare in forma integrata alcuni dei suoi strumenti a casi concreti di elevata valenza industriale. Questa metodologia come anche, più in generale, tutti gli strumenti di miglioramento di affidabilità qui presentati, interessano potenzialmente una vasta gamma di campi produttivi, ma si prestano con particolare efficacia in quei settori dove coesistono elevate produzioni e fortissime esigenze qualitative dei prodotti. Di conseguenza, per la validazione ed applicazione ci si è rivolti al settore dell’automotive, che da sempre risulta particolarmente sensibile ai problemi di miglioramento di affidabilità e sicurezza. Questa scelta ha portato a conclusioni la cui validità va al di là di valori puramente tecnici, per toccare aspetti non secondari di “spendibilità” sul mercato dei risultati ed ha investito aziende di primissimo piano sul panorama industriale italiano.

A robot is a machine that embodies decades of research and development. Born as a simple mechanical devices, these machines evolved together with our technology and knowledge, reaching levels of automation never imagined before. The modern dream is represented by the cooperative robotics, where the robots do not just work for the people, but together with the people. Such result can be achieved only if these machines are able to acquire knowledge through perception, in other words they need to collect sensor measurements from which they extract meaningful information of the environment in order to adapt their behavior. This thesis speaks about the topic of the autonomous object recognition and picking for Automated Guided Vehicles, AGVs, robots employed nowadays in the automatic logistic plants. The development of a technology capable of achieving such task would be a significant technological improvement compared to the structure currently used in this field: rigid, strongly constrained and with a very limited human machine interaction. Automating the process of picking by making such vehicles more smart would open to many possibilities, both in terms of organization of the plants, both for the remarkable economic implications deriving from the abatement of many of the associated fixed costs. The logistics field is indeed a niche, in which the costs of the technology represent the true limit to its spread, costs due mainly to the limitations of the current technology. The work is therefore aimed at creating a stand-alone technology, usable directly on board of the modern AGVs, with minimal modifications in terms of hardware and software. The elements that made possible such development are the multi-sensor approach and data-fusion. The thesis starts with the analysis of the state of the art related of the field of the automated logistic, focusing mostly on the most innovative applications and researches on the automatization of the load/unload of the goods in the modern logistic plants. What emerges form the analysis it is that there is a technological gap between the world of the research and the industrial reality: the results and solutions proposed by the first seem not match the requirements and specification of the second. The second part of the thesis is dedicated to the sensors used: industrial cameras, planar 2D safety laser scanners and 3D time of flight cameras (TOF). For every device a specific (and independent) process is developed in order to recognize and localize Euro pallets: the information that AGVs require in order to perform the picking of an object are the three coordinates that define its pose in the 2D space, $[x,y,\theta]$, position and attitude. The focus is addressed both on the maximization of the reliability of the algorithms and both on the capability in providing a correct estimation of uncertainty of the results. The information content that comes from the uncertainty represents a key aspect for this work, in which the probabilistic characterization of the results and the adoption of the guidelines of the measurement field are the basis for a new approach to the problem. That allowed both the modification of state of the art algorithms both the development of new ones, developing a system that in the final implementation and tests has shown a reliability in the identification process sufficiently high to fulfill the industrial standards, 99\% of positive identifications. The third part is devoted to the calibration of system. In order to ensure a reliable process of identification and picking it is indeed fundamental to evaluate the relations between the sensing devices, sensor-sensor calibration, but also to relate the results obtained with the machine, sensor-robot calibration. These calibrations are critical steps that characterize the measurement chain between the target object and the robot controller. From that chain depends the overall accuracy in performing the forking procedure and, more important, the safety of such operation. The fourth part represents the core element of the thesis, the fusion of the identifications obtained from the different sensors. The multi-sensor approach is a strategy that allows the overcome of possible operational limits due to the measurement capabilities of the individual sensors, taking the best from the different devices and thus improving the performance of the entire system. This is particularly true in the case in which there are independent information sources, these, once fused, provide results way more reliable than the simple comparison of the data. Because of the different typology of the sensors involved, Cartesian ones like the laser and the TOF, and perspective ones like the camera, a specific fusion strategy is developed. The main benefit that the fusion provides is a reliable rejection of the possible false positives, which could cause very dangerous situations like the impact with objects or worst. A further contribution of this thesis is the risk prediction for the maneuver of picking. Knowing the uncertainty in the identification process, in calibration and in the motion of the vehicle it is possible to evaluate the confidence interval associated to a safe forking, the one that occurs without impact between the tines and the pallet. That is critical for the decision making logic of the AGV in order to ensure a safe functionality of the machine during all daily operations. Last part of the thesis presents the experimental results. The aforementioned topics have been implemented on a real robot, testing the behavior of the developed algorithms in various operative conditions.

Present and future space missions rely on systems of increasingly demanding performance for being successful. Drag-free technology is one of the technologies that is fundamental for LISA-Pathfinder, a European Space Agency mission whose launch is planned for the end of September 2015. A purely drag-free object is defined by the absence of all external forces other than gravity. This is not a natural condition and therefore a shield has to be used in order to eliminate the effect of undesired interactions. In space, this is achieved by properly designing the spacecraft that surrounds the object, usually called test mass (TM). Once the TM is subjected to gravity alone its motion is used as a reference for the spacecraft orbit. The satellite orbit is controlled by measuring the relative TM-to-spacecraft position and feeding back the command to the propulsion system that counteracts any non gravitational force acting on the spacecraft. Ideally, the TM should be free from all forces and the hosting spacecraft should follow a pure geodesic orbit. However, the purity of the orbit depends on the spacecraft’s capability of protecting the TM from disturbances, which indeed has limitations. According to a NASA study, such a concept is capable of decreasing operation and fuel costs, increasing navigation accuracy. At the same time, a drag-free motion is required in many missions of fundamental physics. eLISA is an ESA concept mission aimed at opening a new window to the universe, black holes, and massive binary systems by means of gravitational waves. This mission will be extremely challenging and needs to be demonstrated in flight. LISA-Pathfinder is in charge of proving this concept by demonstrating the possibility of reducing the non-gravitational disturbance below a certain demanding threshold. The success of this mission relies on recent technologies in the field of propulsion, interferometry, and space mechanisms. In this frame, the system holding the TM during launch and releasing it in free-fall before the science phase represents a single point of failure for the whole mission. This thesis describes the phenomena, operations, issues, tests, activities, and simulations linked to the release following a system engineering approach. Great emphasis is given to the adhesion (or cold welding) that interferes with the release. Experimental studies have been carried out to investigate this phenomenon in conditions representative of the LISA-Pathfinder flight environment. The last part of the thesis is dedicated to the preliminary design of the housing of the TM in the frame for a low-cost mission conceived at Stanford (USA). Analysis and results are through out presented and discussed. The goal of this thesis is a summary of the activities aimed at a successful LISA-Pathfinder mission. The ambition is to increase the maturity of the technology needed in drag-free projects and therefore provide a starting point for future fascinating and challenging missions of this kind.

In this research work, two ADAS have been proposed, both based on optimal control and manoeuvre jerks as parameters for threat assessment. The first is named “Codriver”, and is a system for driver warning. The second is a sort of completion of the first, since it is designed for autonomous vehicle intervention if the driver does not react to the warnings. The Codriver has been developed by the Mechatronics Group of the University of Trento, which the author is part of, in the framework of the European Project “interactIVe”, to warn the driver for all-around threats safety. It has been then implemented on a real vehicle of Centro Ricerche Fiat, which has been widely tested at the end of the project. On the other hand, for the second system only the main components have been developed by the author during a research period at the University of Tokyo, Japan, and its application is restricted to autonomous obstacle avoidance. In particular, a motion planning algorithm has been used together with a control loop de- signed to execute the planned trajectories. Both systems exploit Optimal Control (OC) for motion planning: the Codriver uses OC to plan real-time ma- noeuvres with humanlike criteria, so that they can be compared to what the driver is doing in order to infer his/her intentions, and warn him if these are not safe; the second system uses OC instead to plan emergency manoeuvres, i.e. neglecting driver actuation limitations and pushing the vehicle towards its physical limits. The initial longitudinal and lateral jerks of the planned manoeuvres are used by both the systems as parameters for risk assessment. Manoeuvre jerks are proportional to pedal and steering wheel velocities, and their initial values thus describe the entity of the correction needed by the driver to achieve a given goal. Since human drivers plan and act with minimum jerk criteria, and are jerk-limited, more and more severe manoeuvres at a given point are not reachable anymore by a human driver, since they require too high initial jerks: initial jerks can be thus considered proportional to the risk level of current situation. For this reason, when the manoeuvres to handle current scenario require jerks beyond a given threshold, the Codriver outputs a warning. This threshold must be lower than driver limits, so that he/she will be able to react to the warning and still have the chance to perform a safe manoeuvre. When the required jerks exceed drivers’ actuation limits, the risk level raises to an upper step, where driver warning would be not effective and autonomous vehicle intervention should be enabled. In obstacle avoidance scenarios, it was demonstrated during driving simulator tests that manoeuvre jerks are more robust parameters for risk assessment than for example time headways, since they are less affected by driver’s age and gender.

Tribology is known as the science of surfaces in relative motion and involves complex interactions over multiple length and time scales. Therefore, friction, lubrication and wear of materials are intrinsically highly multiphysics and multiscale phenomena. Several modelling and simulation tools have been developed in the last decades, always requiring a trade-off between the available computational power and the accurate replication of the experimental results. Despite nowadays it is possible to model with extreme precision elastic problems at various scales, further eorts are needed for taking into account phenomena like plasticity, adhesion, wear, third-body friction and boundary and solid lubrication. The situation becomes even more challenging if considering non-conventional nano-, as in the case of polymer surfaces and interfaces, or microstructures, as for the hierarchical organisations observed in biological systems. Specically, biological surface structures have been demonstrated to present exceptional tribological properties, for instance in terms of adhesion (e.g., the gecko pad), superhydrophobicity (e.g., the lotus leaf) or fluid-dynamic drag reduction (e.g., the shark skin). This has suggested the study and development of hierarchical and/or bio-inspired structures for applications in tribology. Therefore, by taking inspiration from Nature, we investigate the effect of property gradients on the frictional behaviour of sliding interfaces, considering lateral variations in surface and bulk properties. 3D finite-element simulations are compared with a 2D spring-block model to show how lateral gradients can be used to tune the macroscopic coefficients of friction and control the propagation of detachment fronts. Complex microscale phenomena govern the macroscopic behaviour also of lubricated contacts. An example is represented by solid lubrication or third-body friction, which we study with 3D discreteelement simulations. We show the effects of surface waviness and of the modelling parameters on the macroscopic coefficient of friction. Many other natural systems present complex interfacial interactions and tribological behaviour. Plant roots, for instance, display optimised performance during the frictional penetration of soil, especially thanks to a particular apex morphology. Starting from experimental investigations of different probe geometries, we employ the discrete-element method to compute the expended work during the penetration of a granular packing, conrming the optimal bio-inspired shape. This has allowed to follow also an integrated approach including image acquisition and processing of the actual geometries, 3D printing, experiments and numerical simulations. Finally, another interesting example of advanced biological interface with optimised behaviour is represented by biosensing strucviii tures. We employ fluid-structure interaction numerical simulations for studying the response of spiders' trichobothria, which are among the most sensitive biosensors in Nature. Our results highlight the role of the fluid-dynamic drag on the system performance and allow to determine the optimal hair density observed experimentally. Both the third-body problem and the possibility to tune the frictional properties can be considered as the next grand challenges in tribology, which is going to live a "golden age" in the coming years. We believe the results discussed in this Doctoral Thesis could pave the way towards the design of novel bio-inspired structures with optimal tribological properties, for the future development of smart materials and innovative solutions for sliding interfaces.

This thesis presents the development of a full vehicle model tailored for real-time simulation applications. A comprehensive modular simulation framework is developed with the primary goal of providing an accurate and flexible vehicle model for real-time simulations. The vehicle model is developed using a multibody dynamics approach, leveraging efficient formulations and symbolic manipulation to generate cost-effective analytical models. This work presents the model's underlying theory and practical implementation, showcasing the framework's modularity that facilitates seamless integration of external models. This adaptability enables the model's application in a wide range of scenarios, ranging from vehicle dynamics analysis to the development of advanced driver assistance systems. The simulation framework is utilized for Hardware-in-the-Loop (HIL) and Driver-in-the-Loop (DIL) simulations, proving its efficacy in real-world scenarios. Validation against commercial simulation software and real-world vehicle telemetry data further corroborated the model's fidelity and accuracy. Beyond the core vehicle model, this research introduces innovative models that significantly contribute to the simulation efficiency and accuracy. A novel Limited Slip Differential (LSD) model is proposed, employing a smooth equation switching approach to improve numerical efficiency and address issues of conventional approaches such as robustness and the non-exact representation of the locked state. Furthermore, a Symbolic-Numerical Approach is presented for analyzing structure compliance, with a specific application to vehicle suspension compliance analysis. This approach exploits the symbolic manipulation capabilities of computer algebra software to generate efficient analytical models for the suspension's Kinematics and Compliance (K&C) characteristics. This approach not only provides a comprehensive methodology for analyzing suspension compliance but also offers a framework for the generation of symbolic models for any compliant mechanisms, enhancing efficiency in simulation, design, sensitivity analyses, and optimization tasks. In essence, this Ph.D. thesis presents a comprehensive vehicle model for real-time simulation applications, featuring a flexible and modular framework alongside novel models that address specific challenges in vehicle dynamics simulation. Real-time capabilities of the developed model enable closed-loop simulations making it a powerful tool for virtual prototyping, performance evaluation, and controller development in the automotive domain. Practical applications in the field of autonomous vehicles and advanced driver assistance systems showcase the applicability of the proposed framework and models, offering a user-friendly framework for future research and development.

The objective of this dissertation is to develop and test a predictive model for the passive kinematics of human joints based on the energy minimization principle. To pursue this goal, the tibio-talar joint is chosen as a reference joint, for the reduced number of bones involved and its simplicity, if compared with other sinovial joints such as the knee or the wrist. Starting from the knowledge of the articular surface shapes, the spatial trajectory of passive motion is obtained as the envelop of joint configurations that maximize the surfaces congruence. An increase in joint congruence corresponds to an improved capability of distributing an applied load, allowing the joint to attain a better strength with less material. Thus, joint congruence maximization is a simple geometric way to capture the idea of joint energy minimization. The results obtained are validated against in vitro measured trajectories. Preliminary comparison provide strong support for the predictions of the theoretical model.