The dissertation thesis with the topic „Simulation Modelling of Electrical Drives for Selected Critical Applications“ focuses on the area of given applications in civil aviation. The selected application that the thesis deals with is an electrically driven and electronically controlled fuel pump supplying fuel to an aviation motor of the APU type. The thesis gives a comprehensive description of the design cycle of the unit and demonstrates implementing all the required critical functions. In the course of the design of the unit modern techniques in mathematical modelling, simulation, verification, monitoring and prediction of the operation status of airborne equipment were uses to the utmost extent. The purpose of these was to show the suitability of their application with regard to decreasing design time and cost, increasing lifetime and servicing intervals, as well as increasing user comfort and decreasing price. At the same time the required reliability was to be kept. The thesis also aims to prove and verify the suitability of using electronically commutated dc motors in critical applications in civil aviation. To reach this goal, it is necessary to design a robust drive control which would meet the given reliability requirements.

Σκοπός της εργασίας είναι η μελέτη της ανάπτυξης περιβάλλοντος εικονικής και επαυξημένης πραγματικότητας για την υποστήριξη ανθρωποκεντρικών διεργασιών στον τομέα της παραγωγής. Οι τεχνολογίες εικονικής και επαυξημένης πραγματικότητας μπορούν να μειώσουν σημαντικά το χρόνο και το κόστος ανάπτυξης προϊόντων και διεργασιών στην παραγωγή. Αυτή τη στιγμή υπάρχει ένα μεγάλο χάσμα μεταξύ των συμβατικών CAD-βασιζόμενων μεθόδων και των μεθόδων προηγμένης προτυποποίησης και επικύρωσης που προσφέρει η χρήση της εικονικής και επαυξημένης πραγματικότητας. Συνεπώς, υπάρχει ανάγκη εμπλουτισμού των εικονικών περιβαλλόντων με νοημοσύνη, μέσω ενσωμάτωσης της γνώσης, επιτρέποντας την πραγματοποίηση πολύπλοκων εργασιών, μειώνοντας την ανάγκη για ανάπτυξη φυσικών πρωτοτύπων και αυξάνοντας τη δυνατότητα επαναχρησιμοποίησης. Αφενός, περιβάλλοντα επαυξημένης πραγματικότητας που βασίζονται σε σημασιολογική γνώση καθώς και νέες μέθοδοι αλληλεπίδρασης με τον χρήστη μπορούν να παρέχουν τα μέσα για την επανατοποθέτηση του ανθρώπου στην παραγωγική διαδικασία. Αφετέρου, περιβάλλοντα εικονικής πραγματικότητας σε συνδυασμό με τη σημασιολογική γνώση μπορούν να παρέχουν μεθόδους και εργαλεία που ενσωματώνουν τις 3D γεωμετρίες με τις πληροφορίες και τη γνώση, έτσι ώστε οι μηχανικοί να μπορούν αποτελεσματικά να αξιολογήσουν και να διαχειρίζονται εικονικά πρωτότυπα σε ένα εμβυθισμένο και διαδραστικό περιβάλλον. Εντός της παρούσας διατριβής, αναπτύχθηκε μια γενική VR και AR προσέγγιση βασισμένη στην ανάλυση της ανθρώπινης εργασίας και των μεθόδων χαρτογράφησης της γνώσης που υλοποιούνται σε ένα πλαίσιο εικονικής και επαυξημένης πραγματικότητας. Το πλαίσιο VR/AR έχει αναπτυχθεί για να χρησιμοποιηθεί με την προσέγγιση μεθόδου δύο σταδίων χρησιμοποιώντας προηγμένες τεχνικές αλληλεπίδρασης. Η μέθοδος και το πλαίσιο που αναπτύχθηκαν επιβεβαιώνονται μέσα από μια σειρά πραγματικών δοκιμών στην παραγωγή, τόσο της αυτοκινητοβιομηχανίας όσο και της αεροδιαστημικής βιομηχανίας. Τέλος, η αξιολόγηση των προτεινόμενων μεθόδων και του πλαισίου βασίζεται σε πραγματικές δοκιμές στη βιομηχανία με χρήση ποσοτικών δεικτών, επιβεβαιώνοντας τη βελτίωση της ροής εργασιών σε σύγκριση με τη συμβατική. / The aim of this work is to study the development of virtual and augmented reality environment for the support of human-based processes in manufacturing. Virtual and augmented reality technologies can significantly reduce the development time and cost of products and processes in manufacturing. However there is currently a big gap between the conventional CAD-based processes and the advanced prototyping and validation methods offered with the use of VR and AR technology. There is a need for the virtual environments to be enriched with intelligence through the incorporation of knowledge. This will allow for complex tasks to be carried out, thus reducing the need for an ad hoc development, while the reusability of such an environment will be increased. On the one hand, augmented reality environments based on semantic knowledge and new user interaction methods can provide the means for putting the human back in the process loop at manufacturing level. On the other hand, virtual reality environments coupled with semantic knowledge can provide methods and tools that integrate 3D geometries with information/knowledge so that engineers can effectively evaluate and manipulate virtual prototypes in an immersive and interactive environment. Within the current dissertation, a generic VR and AR approach is developed based on human task analysis and knowledge mapping methods that are implemented in a Virtual and Augmented Reality Framework. The VR/AR framework is developed to be used with the two-step method approach using advanced interaction techniques. The developed method and framework are validated through a series of real life manufacturing test cases derived from both the automotive and aerospace industrial practices. Finally, an evaluation of the proposed methods and framework is carried out, based on one of the industrial test cases using quantitative metrics, giving insight on to the improvement of the engineering workflow using the proposed work compared with the conventional physical workflow.

Ideal prostheses are defined as artificial limbs that would permit physically impaired individuals freedom of movement and independence rather than a life of disability and dependence. Current lower limb prostheses range from a single mechanical revolute joint to advanced microprocessor controlled mechanisms. Despite the advancement in technology and medicine, current lower limb prostheses are still lacking an actuation element, which prohibits patients from regaining their original mobility and improving their quality of life. This thesis aims to design and test a Pneumatic Artificial Muscle that would actuate lower limb prostheses. This would offer patients the ability to ascend and descend stairs as well as standing up from a sitting position. A comprehensive study of knee biomechanics is first accomplished to characterize the actuation requirement, and subsequently a Pneumatic Artificial Muscle design is proposed. A novel design of muscle end fixtures is presented which would allow the muscle to operate at a gage pressure surpassing 2.76 MPa (i.e. 400 psi) and yield a muscle force that is at least 3 times greater than that produced by any existing equivalent Pneumatic Artificial Muscle. Finally, the proposed Pneumatic Artificial Muscle is tested and validated to verify that it meets the size, weight, kinetic and kinematic requirements of human knee articulation.

Ideal prostheses are defined as artificial limbs that would permit physically impaired individuals freedom of movement and independence rather than a life of disability and dependence. Current lower limb prostheses range from a single mechanical revolute joint to advanced microprocessor controlled mechanisms. Despite the advancement in technology and medicine, current lower limb prostheses are still lacking an actuation element, which prohibits patients from regaining their original mobility and improving their quality of life. This thesis aims to design and test a Pneumatic Artificial Muscle that would actuate lower limb prostheses. This would offer patients the ability to ascend and descend stairs as well as standing up from a sitting position. A comprehensive study of knee biomechanics is first accomplished to characterize the actuation requirement, and subsequently a Pneumatic Artificial Muscle design is proposed. A novel design of muscle end fixtures is presented which would allow the muscle to operate at a gage pressure surpassing 2.76 MPa (i.e. 400 psi) and yield a muscle force that is at least 3 times greater than that produced by any existing equivalent Pneumatic Artificial Muscle. Finally, the proposed Pneumatic Artificial Muscle is tested and validated to verify that it meets the size, weight, kinetic and kinematic requirements of human knee articulation.