The eigenstructure assignment scheme for robust multivariable feedback control is extended to redundantly actuated dynamical systems. It is shown that an orthonormal set of close loop eigenvectors is always exactly assignable in the case of redundant actuation proving the inherent robustness in the control design methodology. A choice of close loop eigenvector set to minimize the feedback gain matrix is suggested. Partial Eigenstructure Assignment methodology is proposed for second order mechanical systems. A methodology for coordinated actuation of redundant actuator sets by a trained weighted minimum norm solution is presented. To apply the methodology to hyper-redundant actuator arrays, for application to smart actuator arrays, a novel adaptive discretization algorithm is proposed. The adaptive aggregation strategy, based on the physics of the system, introduces nodes, to optimize a performance index of the overall plant model. The dimensionality of the inputs thus reduces to a finite number, making it a candidate plant for control by the robust redundant control scheme. The adaptive aggregation together with robust redundant control methodology is demonstrated on a finite element model of a novel morphing wing. This schema unifies the traditionally disparate methods of modeling and controller design.

In recent years, there has been increasing interest in the advancement of microrobotic systems in micro-engineering, micro-fabrication, biological research and biomedical applications. Untethered magnetic-based microrobotic systems are one of the most widely developing groups of microrobotic systems that have been extensively explored for biological and biomedical micro-manipulations. These systems show promise in resolving problems related to on-board power supply limitations as well as mechanical contact sealing and lubrication. In this thesis, a high precision magnetic untethered microrobotic system is demonstrated for micro-handling tasks. A key aspect of the proposed platform concerns the integration of magnetic levitation technology and bilateral macro-micro teleoperation for human intervention to avoid imperceptible failures in poorly observed micro-domain environments. The developed platform has three basic subsystems: a magnetic untethered microrobotic system (MUMS), a haptic device, and a scaled bilateral teleoperation system. The MUMS produces and regulates a magnetic field for non-contact propelling of a microrobot. In order to achieve a controlled motion of the magnetically levitated microrobot, a mathematical force model of the magnetic propulsion mechanism is developed and used to design various control systems. In the workspace of 30 ?? 32 ?? 32 mm ³, both PID and LQG\LTR controllers perform similarly the position accuracy of 10 ?? m in a vertical direction and 2 ?? m in a horizontal motion. The MUMS is equipped with an eddy-current damper to enhance its inherent damping factor in the microrobot's horizontal motions. This paper deals with the modeling and analysis of an eddy-current damper that is formed by a conductive plate placed below the levitated microrobot to overcome inherent dynamical vibrations and improve motion precision. The modeling of eddy-current distribution in the conductive plate is investigated by solving the diffusion equation for vector magnetic potential, and an analytical expression for the horizontal damping force is presented and experimentally validated. It is demonstrated that eddy-current damping is a crucial technique for increasing the damping coefficient in a non-contact way and for improving levitation performance. The damping can be widely used in applications of magnetic actuation systems in micro-manipulation and micro-fabrication. To determine the position of the microrobot in a workspace, the MUMS uses high-accuracy laser sensors. However, laser positioning techniques can only be used in highly transparent environments. A novel technique based on real-time magnetic flux measurement has been proposed for the position estimation of the microrobot in case of laser beam blockage, whereby a combination of Hall-effect sensors is employed to find the microrobot's position in free motion by using the produced magnetic flux. In free motion, the microrobot tends to move toward the horizontally zero magnetic field gradient, B_max location. As another key feature of the magnetic flux measurement, it was realized that the applied force from the environment to the microrobot can be estimated as linearly proportional to the distance of the microrobot from the B_max location. The developed micro-domain force estimation method is verified experimentally with an accuracy of 1.27 ?? N. A bilateral macro-micro teleoperation technique is employed in the MUMS for the telepresence of a human operator in the task environment. A gain-switching position-position teleoperation scheme is employed and a human operator controls the motion of the microrobot via a master manipulator for dexterous micro-manipulation tasks. The operator can sense a strong force during micro-domain tasks if the microrobot encounters a stiff environment, and the effect of hard contact is fed back to the operator's hand. The position-position method works for both free motion and hard contact. However, to enhance the feeling of a micro-domain environment in the human operator, the scaled force must be transferred to a human, thereby realizing a direct-force-reflection bilateral teleoperation. Additionally, a human-assisted virtual reality interface is developed to improve a human operator's skills in using the haptic-enabled platform, before carrying out an actual dexterous task.

Mobile legged robots have the potential to restructure many aspects of our lives in the near future. Whether for applications in household care, entertainment, or disaster response, these systems depend on high-performance actuators to improve their basic capabilities. The work presented here focuses on developing new high-performance actuators, specifically series elastic actuators, to address this need. We adopt a system-wide optimization approach, dealing with factors which influence performance at the levels of mechanical design, electrical system design, and control. Using this approach and based on a set of performance metrics, we produce an actuator, the UT-SEA, which achieves leading empirical results in terms of power-to-weight, force control, size, and system efficiency. We also develop general high-performance control techniques for both force- and position-controlled actuators, some of which were adopted for use on NASA-JSC's Valkyrie Humanoid robot and were used during DARPA's DRC Trials 2013 robotics competition. / text

Magnetic micro-robots are small robots under 1mm in size, made of magnetic materials, with relatively simple structures and functionalities. Such micro-robots can be actuated and controlled remotely by externally applied magnetic fields, and hence have the potential to access small and enclosed spaces. Most of the existing magnetic micro-robots can operate in wet environments. When the robots are actuated by the applied magnetic field to move inside a viscous liquid, they invoke flow motions around them inside the liquid. The induced flows are relatively local as the velocity of these flows decays rapidly with the distance from a moving robot, and the flow patterns are highly correlated with the motions of the micro-robots which are controllable by the applied magnetic field. Therefore, it is possible to generate local flow patterns that cannot be easily done using other microfluidic techniques. In this work we propose to use rotational motion of the magnetic micro-robots for local manipulation of flows. We employ electromagnetic techniques to successfully deliver actuation and motion control onto the micro-robots. Rotational magnetic field is applied to induce rotational motion of micro-robots both when they stay near a surface and are suspended in the liquid. Rotational flows are locally generated in the vicinity of micro-robots inside the viscous liquid. Implementation of three major applications using the flows generated by the rotating micro-robots are demonstrated in this work: 1) Two-dimensional (2D) non-contact manipulation of micro-objects. 2) Three-dimensional (3D) propulsion for the micro-robot to swim in a liquid. 3) Size-based sorting of micro-particles in microfluidic channels under continuous flow. The first two applications occur in otherwise quiescent liquid, while the third requires the presence of non-zero background flow. For the first application, we propose two methods to achieve precise positioning of the microrobots on a surface: 1) Using visual-feedback-control to adjust the rotation for one single microrobot. Micro-robot can be precisely positioned at any location on a surface using this method. 2) Using a specially prepared surface with magnetic micro-docks embedded in it, which act as local magnetic traps for multiple micro-robots to hold their positions and operate in parallel. Physical models are established for both the micro-robot and the micro-objects present in the induced rotational flow. The rotational flows induced by rotating micro-robots are studied with numerical simulations. Experimental demonstrations are first given at sub-millimeter scale to verify the proposed method. Micro-manipulation of polymer beads is performed with both positioncontrol methods. Automated micro-manipulation is also achieved using visual-feedback. Micromanipulation at micron-scale is then performed to demonstrate the scalability and versatility of the proposed method. Non-contact manipulation is achieved for various micro-objects, including biological samples, using a single spherical micro-robot. Inspired by flagellated microorganisms in nature, we explore the hydrodynamics of an elastic rod-like structure - the artificial flagellum, and verify by both simulation and experiments that rotation and deformation of such structure can result in a propulsive force on a micro-robot it is attached to. Optimization of flagellum geometry is achieved for a single flagellum. A swimming micro-robot design with multiple flexible flagella is proposed and fabricated via an inexpensive micro-fabrication process involving photolithography, micro-molding and manual assembly. Experiments are perform to characterize the propulsive force generation and the resulting swimming performance of the fabricated micro-robots. It is demonstrated that the swimming speed can be improved by increasing the number of attached flagella. For the size-based sorting application, we integrate the micro-robots into microfluidic channels by using the substrate embedded with magnetic micro-docks, which are capable of holding the robots under continuous flow inside the channels while the robots spin. Numerical analysis is carried out of the flows inside the microfluidic channel in the presence of rotating micro-robots, and a physical model is established and discussed for size-based lateral migration of spherical micro-objects inside the induced rotational flows. Experimental demonstrations are performed for using the induced rotational flows to divert the trajectories of micro-particles based on their sizes under continuous flow. In addition, we propose the method of using the two photon polymerization (TPP) technique to fabricate magnetic micro-robots with complex shapes. The method could also achieve fabrication of arrays of micro-robots for more sophisticated applications. However, experimental results prove that the TPP is insufficient to achieve magnetic micro-robots that meet our needs for size-based sorting application due to physical limitations of the materials. Despite that, it is potentially powerful and suitable for fabrication of micro-robots with complex structures at small scales.

In an age where computers challenge the smartest human beings in cognitive tasks, the conspicuous discrepancy between robot and animal locomotion appears paradoxical. While animals can move around autonomously in complex environments, today’s robots struggle to independently operate in such surroundings. There are many reasons for robots’ inferior performance, but arguably the most important one is our missing understanding of complexity. This thesis introduces the notion of discrete actuation for the study of locomotion in robots and animals. The actuation of a system with discrete actuation is restricted to be applied at a finite number of instants in time and is impulsive. We find that, despite their simplicity, such systems can predict various experimental observations and inspire novel technologies for robot design and control. We further find that, through the study of discrete actuation, causal relationships between actuation and resulting behaviour are revealed and become quantifiable, which relates the findings presented in this thesis to the broader concepts of complexity, self-organisation, and self-stability. We present four case studies in Chapters 3-6 which demonstrate how the concept of discrete actuation can be employed to understand the physics of locomotion and to facilitate novel robot technologies. We first introduce the impulsive eccentric wheel model which is a discretely actuated system for the study of hopping locomotion. We find that the model predicts robot hopping trajectories and animal related hopping characteristics by reducing the dynamics of hopping–usually described by hybrid differential equations–to analytic maps. The reduction of complexity of the model equations reveals the underlying physics of the locomotion process, and we identify the importance of robot shape and mass distribution for the locomotion performance. As a concrete application of the model, we compare the energetics of hopping and rolling locomotion in environments with obstacles and find when it is better to hop than to roll, based on the fundamental physical principles we discover in the model analysis. The theoretical insights of this modelling approach enable new actuation techniques and design for robots which we display in Robbit; a robot that uses strictly convex foot shapes and rotational impulses to induce hopping locomotion. We show that such systems outperform hopping with non-strictly convex shapes in terms of energy effective and robust locomotion. A system with discrete actuation motivates the exploitation of shape and the environment to improve locomotion dynamics, which reveals advantageous effect of inelastic impacts between the robot foot and the environment. We support this idea with experimental results from the robot CaneBot which can change its foot shape to induce timed impacts with the environment. Even though inelastic impacts are commonly considered detrimental for locomotion dynamics, we show that their appropriate control improves the locomotion speed considerably. The findings presented in this thesis show that discrete actuation for locomotion inspires novel ways to appreciate locomotion dynamics and facilitates unique control and design technologies for robots. Furthermore, discrete actuation emphasises the definition of causality in complex systems which we believe will bring robots closer to the locomotion behaviour of animals, enabling more agile and energy effective robots.

This study retrieves the long-abandoned thought of an early twentieth-century Jesuit theologian, Maurice de la Taille (I872-t933), reassessing his theory of eucharistic sacrifice in light of his theology of grace and contemplation. His major work, the three volume Mysterium Fidei (L921), provides an integrated account of sacrifice, one which responsively embraces the multiple and often controversial aspects of the topic of sacrifice. De la Taille rejects a supercessionist treatment of Hebrew ritual sacrifice; he incorporates a sophisticated theory of sacrifice as sign and gift; and he allows the fullness of theological tradition-scripture, the Fathers (East and West), Thomistic thought, conciliar and papal teaching, and the witness of liturgical prayer and mystical theology to inform his theory of Christian sacrifice. In surprising ways, de la Taille's magisterial work on eucharistic sacrifice forestalls the post-Vatican II liberal anxieties about sacrifice. He decidedly challenges the formidable heritage of sixteenth and seventeenth century immolation-focused eucharistic theology by providing a patristically-rich theology of sacrifice, one that stands rooted in a spirituality of prayer and ascetic practice which cannot be segregated from the ecclesial oblation of Christ's sacrifice. With his focus on the affect and desire of the offerer of sacrifice, de la Taille anticipates the 'subjective turn' that emerged in mid-twentieth century eucharistic theology, and in a way that revitalizes the critical role of ecclesial ritual sacrifice in the transformation of that desire. / Thesis (PhD) — Boston College, 2008. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Theology.

<p>This bachelor’s degree project has been conducted at the Innovation and Design Engineering programme at Karlstad University and responds to 22.5 ETCS credits. The project has been carried out in co-operation with Rolls-Royce AB in Kristinehamn.</p><p>Based upon a virtual order concerning a super yacht the objective has been to develop a controllable pitch propeller that is adjusted using electro mechanics, to eliminate the use of hydraulic oils and thus the risk of leakage to the seawater.</p><p>The pre-study consisted of the two first phases of QFD-analysis (Quality Function Deployment). The first phase consists of gathering customer requirements. Representatives from different functions within Rolls-Royce AB were interviewed, as representatives for the customer. The demands they presented were used to find product features and functionalities.</p><p>The results were put together in two Houses of Quality. The first house shows the relations between requirements and features/functionalities and their respective relevance in correlation to each other. House of Quality two describes the relations between features/functionalities and design solutions in a similar way.</p><p>Based upon the QFD-analysis, a specification was generated to be used as guidance to generate ideas of how to solve the problem. A number of brainstorming methods were used and students from Karlstad University and Rolls-Royce AB participated in those sessions. Overall, some twenty ideas were gathered and five of those were considered feasible concepts.</p><p>For further development, two of those concepts were chosen, using relative and weighted decision matrixes. This development consisted of solid modelling, based on current propeller arrangement designs, and stress calculations of the new parts of the system.</p><p>Both concepts consist of an electrical engine, powering a trapezoid screw, which moves the crosshead. In Concept 1, the screw is mounted directly into the crosshead while in Concept 2; a push rod is used to transmit the motion. Both concepts appeared to meet up to the objectives, though Concept 1 fulfilled more demands and to a greater extent.</p><p>For further development of this product, customer inquiries with closer customer contacts need to be conducted. It will also be necessary to contact the concerned classing societies, since current classification rules not can be applied to electromechanically controlled propellers.</p> / <p>Detta examensarbete har utförts för examen på Innovations- och designingenjörsprogrammet vid Karlstads universitet och motsvarar 22,5 hp. Projektet har genomförts tillsammans med Rolls-Royce AB i Kristinehamn.</p><p>Baserad på en virtuell order på en superyacht har målet varit att utveckla en justerbar propeller som regleras helt med elektromekanik. Detta för att eliminera användandet av hydraulolja och därmed risken för läckage till havsvattnet.</p><p>Förstudien har bestått av de två första faserna av QFD-studie (Quality Function Deployment). Den första fasen består av insamlande av kundernas önskemål. Olika representanter inom företaget, som fått representera slutkunden, intervjuades och de önskemål som kom fram användes för att hitta produktegenskaper och funktioner.</p><p>Resultaten sammanställdes i två kvalitetshus (House of Quality). Det första visar förhållandet mellan önskemål och egenskaper/funktioner samt deras respektive relevans i förhållande till varandra. Hus två beskriver på samma sätt förhållandet mellan egenskaper/funktioner och konstruktionslösningar.</p><p>Utifrån QFD-studien sammanställdes en specifikation som användes som mall för att generera idéer kring lösningen av problemet. Ett antal olika kreativitetsmetoder användes och studenter från Karlstads universitet samt anställda från Rolls-Royce AB deltog i sessionerna. Totalt togs ett tjugotal idéer fram och fem av dessa bedömdes vara genomförbara koncept.</p><p>Två av koncepten valdes ut, med hjälp av en relativ viktad kriterievalsmatris, för att utvecklas vidare. Utvecklingen bestod i att göra solidmodeller, baserat på de befintliga delarna i propellerarrangemanget, samt hållfasthetsberäkningar av de nya delar som kom att ingå i systemet.</p><p>Båda koncepten bygger på att en trapetsgängad skruv, driven av en elmotor, förflyttar kolvstångshuvudet. I koncept 1 är skruven monterad direkt i detta och i koncept 2 överförs rörelsen via en tryckstång. Båda koncepten föreföll sig lösa det uppsatta problemet även om koncept 1 visade sig uppfylla fler önskemål och i högre utsträckning.</p><p>För att komma vidare med produkten bör kundundersökningar med närmare kontakter till kunden genomföras. Det är också nödvändigt att kontakta berörda klassningssällskap, då dagens klassningsregler ej kan appliceras på elektromekaniska propellrar.</p>

This bachelor’s degree project has been conducted at the Innovation and Design Engineering programme at Karlstad University and responds to 22.5 ETCS credits. The project has been carried out in co-operation with Rolls-Royce AB in Kristinehamn. Based upon a virtual order concerning a super yacht the objective has been to develop a controllable pitch propeller that is adjusted using electro mechanics, to eliminate the use of hydraulic oils and thus the risk of leakage to the seawater. The pre-study consisted of the two first phases of QFD-analysis (Quality Function Deployment). The first phase consists of gathering customer requirements. Representatives from different functions within Rolls-Royce AB were interviewed, as representatives for the customer. The demands they presented were used to find product features and functionalities. The results were put together in two Houses of Quality. The first house shows the relations between requirements and features/functionalities and their respective relevance in correlation to each other. House of Quality two describes the relations between features/functionalities and design solutions in a similar way. Based upon the QFD-analysis, a specification was generated to be used as guidance to generate ideas of how to solve the problem. A number of brainstorming methods were used and students from Karlstad University and Rolls-Royce AB participated in those sessions. Overall, some twenty ideas were gathered and five of those were considered feasible concepts. For further development, two of those concepts were chosen, using relative and weighted decision matrixes. This development consisted of solid modelling, based on current propeller arrangement designs, and stress calculations of the new parts of the system. Both concepts consist of an electrical engine, powering a trapezoid screw, which moves the crosshead. In Concept 1, the screw is mounted directly into the crosshead while in Concept 2; a push rod is used to transmit the motion. Both concepts appeared to meet up to the objectives, though Concept 1 fulfilled more demands and to a greater extent. For further development of this product, customer inquiries with closer customer contacts need to be conducted. It will also be necessary to contact the concerned classing societies, since current classification rules not can be applied to electromechanically controlled propellers. / Detta examensarbete har utförts för examen på Innovations- och designingenjörsprogrammet vid Karlstads universitet och motsvarar 22,5 hp. Projektet har genomförts tillsammans med Rolls-Royce AB i Kristinehamn. Baserad på en virtuell order på en superyacht har målet varit att utveckla en justerbar propeller som regleras helt med elektromekanik. Detta för att eliminera användandet av hydraulolja och därmed risken för läckage till havsvattnet. Förstudien har bestått av de två första faserna av QFD-studie (Quality Function Deployment). Den första fasen består av insamlande av kundernas önskemål. Olika representanter inom företaget, som fått representera slutkunden, intervjuades och de önskemål som kom fram användes för att hitta produktegenskaper och funktioner. Resultaten sammanställdes i två kvalitetshus (House of Quality). Det första visar förhållandet mellan önskemål och egenskaper/funktioner samt deras respektive relevans i förhållande till varandra. Hus två beskriver på samma sätt förhållandet mellan egenskaper/funktioner och konstruktionslösningar. Utifrån QFD-studien sammanställdes en specifikation som användes som mall för att generera idéer kring lösningen av problemet. Ett antal olika kreativitetsmetoder användes och studenter från Karlstads universitet samt anställda från Rolls-Royce AB deltog i sessionerna. Totalt togs ett tjugotal idéer fram och fem av dessa bedömdes vara genomförbara koncept. Två av koncepten valdes ut, med hjälp av en relativ viktad kriterievalsmatris, för att utvecklas vidare. Utvecklingen bestod i att göra solidmodeller, baserat på de befintliga delarna i propellerarrangemanget, samt hållfasthetsberäkningar av de nya delar som kom att ingå i systemet. Båda koncepten bygger på att en trapetsgängad skruv, driven av en elmotor, förflyttar kolvstångshuvudet. I koncept 1 är skruven monterad direkt i detta och i koncept 2 överförs rörelsen via en tryckstång. Båda koncepten föreföll sig lösa det uppsatta problemet även om koncept 1 visade sig uppfylla fler önskemål och i högre utsträckning. För att komma vidare med produkten bör kundundersökningar med närmare kontakter till kunden genomföras. Det är också nödvändigt att kontakta berörda klassningssällskap, då dagens klassningsregler ej kan appliceras på elektromekaniska propellrar.

Spasticity is a neurological impairment that presents itself in the form of a continuous muscle contraction, with the key motor deficit being impaired hand function. Hand exoskeleton technologies play a vital role in the therapeutic rehabilitation of this condition. The optimal design of these devices is currently a challenge due to the limited availability of actuation devices that are light weight, portable, and aesthetically pleasing. Natural muscles have many favourable characteristics, such as their high power-to-weight ratio, efficient energy conversion, and fast actuation times. Unfortunately, traditional systems such as pneumatics muscles and electromagnetic motors have yet to attain similar properties. These traditional actuators exhibit hysteretic performance, high manufacturing cost, low stroke, and limited cycle life. In recent years a new category of actuators has been developed from highly twisted and coiled low-cost nylon fibres such as fishing line and conductive sewing thread. These muscles produce a high specific work per cycle with a reversible contraction. This thesis develops and tests these twisted and coiled polymer (TCP) actuators using various nylon and polyethylene polymers in order to establish a foundation for their implementation as a novel actuation device in a spastic hand exoskeleton. An initial comprehensive experimental evaluation of several nylon fibres is completed by attempting to reproduce the work of previous researchers. Subsequently, the information obtained is taken and adapted to the development of UHMWPE TCPs and other types of nylon monofilament. This thesis characterizes the contractility and force output of these novel actuation devices.

abstract: The human shoulder plays an integral role in upper limb motor function. As the basis of arm motion, its performance is vital to the accomplishment of daily tasks. Impaired motor control, as a result of stroke or other disease, can cause errors in shoulder position to accumulate and propagate to the entire arm. This is why it is a highlight of concern for clinicians and why it is an important point of study. One of the primary causes of impaired shoulder motor control is abnormal mechanical joint impedance, which can be modeled as a 2nd order system consisting of mass, spring and damper. Quantifying shoulder stiffness and damping between healthy and impaired subjects could help improve our collective understanding of how many different neuromuscular diseases impact arm performance. This improved understanding could even lead to better rehabilitation protocols for conditions such as stroke through better identification and targeting of damping dependent spasticity and stiffness dependent hypertonicity. Despite its importance, there is a fundamental knowledge gap in the understanding of shoulder impedance, mainly due to a lack of appropriate characterization tools. Therefore, in order to better quantify shoulder stiffness and damping, a novel low-inertia shoulder exoskeleton is introduced in this work. The device was developed using a newly pioneered parallel actuated robot architecture specifically designed to interface with complex biological joints like the shoulder, hip, wrist and ankle. In addition to presenting the kinematics and dynamics of the shoulder exoskeleton, a series of validation experiments are performed on a human shoulder mock-up to quantify its ability to estimate known impedance properties. Finally, some preliminary data from human experiments is provided to demonstrate the device’s ability to collect the measurements needed to estimate shoulder stiffness and damping while worn by a subject. / Dissertation/Thesis / Doctoral Dissertation Mechanical Engineering 2020