This thesis is centered upon the published A Novel Method and Exoskeletons for Whole-arm Gravity Compensation (Turner, Hull 2020), and includes a novel concept for supporting the weight of a person's arm or robotic linkage. The design is capable of supporting weights held near the hand, and provides support regardless of position. This support is provided with a pantograph. The upper-arm and forearm bars are mirrored by smaller copies. Force applied to a pull point on the scaled copy of the arm is flipped and applied at a support point on the forearm or to a tool near the hand. Two exoskeletons, using different linkages make use of the pantograph design. These include the Panto-Arm Exo, which uses it's slim, reduced size to comfortably assist users in lifting their arm, and the Panto-Tool Exo which is designed for a support point that coincides with a mass representing a heavy tool. The differing topologies and purposes of these two devices resulted in different qualities regarding their ability to lift weight. The Panto-Arm Exo was specifically used in human subject testing, in which fourteen users wore electromyography electrodes and performed simple arm movements and holding tasks. While the Panto-Arm Exo did not undergo stringent design improvements or user-specific optimization, the device was shown to reduce muscle use in the measured upper-arm muscles for certain arm positions. / Master of Science / This thesis is centered upon the published A Novel Method and Exoskeletons for Whole-arm Gravity Compensation (Turner, Hull 2020), includes a new way to lift a person's arm or robotic linkage. The design can lift weights close to the hand regardless of arm placement. This support is provided with a pantograph. The pantograph design is based on a mirrored, smaller copy of the upper-arm and forearm bars, which is pulled downwards to create an upwards support force at chosen support point. This point is based underneath the forearm or at a heavy tool. The concept is similar to pushing down on a teeter-totter in order to prevent the other end from dropping. Two exoskeletons, using different linkages make use of this pantograph design. The Panto-Arm Exo is slim and light. It is made to help users in lift their arm by supporting its weight. The Panto-Tool Exo has a support point that located where a mass representing a heavy tool sits. The changes between both devices means that they display different lifting qualities. The Panto-Arm Exo was worn by 14 people, also wearing electrodes that measured muscle activation. These users held weights and moved their arms around while muscle activation was recorded. While the Panto-Arm Exo wasn't fine-tuned or adjusted for individual people, it was shown to reduce muscle activation in the measured upper-arm muscles for some of the arm placements.

We present and analyze two arm exoskeletons based on a pantograph linkage that allow for the support of 89~N (20~pounds) at the user's hand. Using a pantograph linkage allows for a constant force to be created at the hand in any orientation when a constant vertical force is supplied to the other side of the pantograph. We present several topologies and analyze them based on feasibility of manufacture and ability to provide a near vertical force to the pantograph linkage. Simulations are created using the best topologies and the resulting forces at the hand are reported. The mechanical design of an unpowered (passive) exoskeleton which uses a gas spring mechanism is presented. Additionally, simulations and block-CAD of a powered (active) exoskeleton which uses a motor for the supply of force are presented. The performance of the passive exoskeleton is qualitatively compared with simulations. / Master of Science / A wearable device or exoskeleton is presented which is designed to help a user support a weight of 20 pounds (89~N) at their hand. A pantograph linkage arm exoskeleton provides forces to the hand which are equal to the force provided to the linkage divided by the linkage's ratio. Providing a force to the linkage that is purely vertical will result in a purely vertical force at the hand. Layouts of the exoskeleton components which produce a near-vertical force for the linkage are explored. The more promising layouts are simulated and the forces are compared based on how vertical the forces are. The design of an unpowered exoskeleton is also presented, which uses a gas spring mechanism to provide force. Additionally, simulation results for the unpowered exoskeleton and the basic design and analysis of a powered exoskeleton are presented.

This thesis presents the design, simulation, and evaluation of a passive, wearable, and human-scale actuator that includes pulleys and uses polymers for energy storage. Repetitive tasks such as packing boxes on an assembly line may require high strength movements of the shoulder, arm, and hand and may result in musculoskeletal disorders. With the objective to offset the weight of the arm and thereby lower the forces on the muscles in the shoulder and arm, this actuator is able to provide gravity compensation for the upper extremities of workers, if used in conjunction with an arm exoskeleton. The actuator is passive, meaning that it does not use motors or sensors, but instead creates a force on a cable that is a function of the displacement of the cable. This thesis details the design of the actuator and the selection of an appropriate polymer for use with the actuator. To determine the best polymer for this application, tests were conducted on nine polymers to ind their average Young's modulus and their hysteresis. A 90A abrasion-resistant polyurethane rubber belt was used in the final design due to its high modulus and low hysteresis. The final actuator design was tested in an Instron machine to validate its performance. During testing, the actuator provided 720N in extension and 530N in retraction, which are roughly 112% and 83% of the torque required to lift a human arm, respectively. / Master of Science

Testning av flygkontroller på en verklig kvadrokopter är en farlig och utmanande process eftersom kvadrokoptern kan krascha om flygkontrollern inte fungerar eller ifall operatören saknar flygerfarenheter. Den nuvarande lösningen är att montera kvadrokoptern i en mekanisk anordning som möjliggör testning av flygkontroller i säkra miljöer. Problemet med de befintliga testanordningarna är att de inte kan ge realistiska simuleringsförhållanden eftersom de i viss mån påverkar kvadrokopterns rörelse med följden att flygkontroller som utvecklas har begränsad grad av kontroll på kvadrokoptern. Syftet är att utforma en mekanisk anordning som ska ge möjlighet att både testa samt övningsflyga kvadrokoptern utan risk för personliga och materiella skador. Målet är att ta fram ritningar som ska kunna utgöra underlag för framtagning av en testprototyp. En litteraturstudie på befintliga testanordningar genomfördes som användes som underlag tillsammans med kvalitetshuset för att ta fram en kravspecifikation. Därefter genererades ett antal koncept som utvärderades med hjälp av beslutsmatris. Det valda konceptet modellerades sedan i CAD-programmet och utifrån den virtuella modellen konstruerades en verklig modell i trä som testades för att verifiera dess funktion. Resultatet är en fjäderbalanserad testanordning med sex frihetsgrader. Det är en konstruktion i aluminium innehållande en mekanisk arm som ger tre translationsfrihetsgrader, ett kulledsfäste som ger tre rotationsfrihetsgrader samt dragfjädrar för att tyngdkraftskompensera systemet. Testning av trä-modellen uppvisar att kvadrakoptern måste framföras i full fart för att styras tillsammans med armen eftersom friktionen mellan testanordningens leder är hög. Under förutsättning att friktionen mellan lederna kan hanteras verkar det att testanordningen uppfyller de ställda teoretiska förutsättningarna för att inte ha någon väsentlig påverkan på kvadrokoptern. Ändå kravs det kvalificerade tester innan något påstående att testanordningen inte påverkar kvadrokopterns rörelse och därmed kan ge realistiska flygsimuleringsförhållanden, ska kunna anges. / Testing of autonomous flight controllers on a real quadrocopter is a dangerous and challenging process because the quadrocopter can crash in case the flight controller does not function properly or in case the operator has no flight experience. The current solution is to mount the quadrocopter on a teststand, which allow the testing of flight controller in safe environments. The problem with the existing teststands is that they cannot provide realistic free flight conditions as they, to some extent, affect quadrocopter’s movement. Consequently, the developed flight controller is partially able to control the quadrocopter. The purpose with this study is to design a mechanical device for use in testing and learning to fly a quadrocopter without the risk of crashing the flying model or harming the people involved. The goal is to provide drawings for developing a test prototype.In order to understand the problem a literature review of previous test devices was carried out. The findings from the literature review were used in combination with Quality Function Deployment technique to create a House of Quality and thus develop a set of engineering specifications. After that, a number of concepts was generated and then evaluated by Pugh’s method. The selected concept was modeled in the CAD-software and based on the virtual model, a real model made of wood was constructed and tested in order to verify the function of the testbed. The final result is a spring-balanced test device with six degrees of freedom. It is a structure consisting of a mechanical arm providing three translational degrees of freedom, a swivel joint with three rotational degrees of freedom and a set of extension springs to achieve gravity balancing. The experimental results from the wooden model shows that the quadrocopter is required to fly at full speed in order for it to operate with the arm due to the high friction between the joints. Under the condition that the friction between the joints can be managed, the test device seems to fulfill the theoretical requirements for simulating free flight condition. Nevertheless, it requires specialized and advanced testing before any assertion that the test device does not affect the dynamics of quadrocopter and thus it can provide completely realistic flight conditions, can be made.

Cette thèse traite de la compensation magnétique de pesanteur. Tout d’abord, des expériences de lévitation magnétique de fluides sont interprétées à l’aide d’un potentiel magnéto-gravitationnel SL. Puis, l’utilisation d’une méthode générale d’analyse de la force magnétique grâce aux harmoniques du champ magnétique est développée. Elle souligne l’importance et le rôle de chacun des trois premiers harmoniques du champ magnétique sur les configurations de forces résultantes inhérentes à la compensation magnétique de pesanteur. En géométrie cylindrique (invariante par translation) diverses combinaisons de forces d’origines magnétique, gravitationnelle et centrifuge offrent des perspectives nouvelles pour la lévitation magnétique. Une combinaison judicieuse des forces magnétiques et centrifuges permet de compenser exactement la pesanteur sur des matériaux diamagnétiques. En géométrie axisymétrique (invariante par rotation), le dimensionnement de stations de lévitation d’oxygène, techniquement réalisables (NbTi@4,2K), est présenté. Ces stations permettent de léviter des volumes d’oxygène supérieurs à 1 litre avec des inhomogénéités inférieures à 1%. La constitution de ces stations rend possible les variations spatiales et temporelles des configurations d’accélérations résultantes. Enfin, la compensation magnétique dynamique de gravité, à l’aide d’une station de lévitation réelle, est étudiée afin de simuler des phases d’accélération ou de décélération d’engins spatiaux / The thesis deals with magnetic gravity compensation. First of all magnetic levitation experiments are explained with the help of a magneto-gravitational potential SL. Next, a general analysis method of the magnetic force is developed which employs magnetic field harmonics. The method underlines both the significance and role of the first three magnetic field harmonics on the resulting forces inherent in magnetic gravity compensation. In cylindrical geometry – with translational invariance – various combination of magnetic, gravitational and centrifugal forces open new possibilities for the magnetic levitation. A suitable combination of both magnetic and centrifugal forces allows exactly compensating gravity on diamagnetic materials. In axisymmetric geometry – with rotational invariance – designs of feasible oxygen magnetic levitation stations are introduced (NbTi@4,2K). Levitation of oxygen volumes more than one litre with inhomogeneities less than 1% can be accomplished within these magnetic levitation facilities. The constitution of the stations makes possible both spatial and temporal variations of the resulting acceleration configurations. At last the dynamic magnetic compensation of gravity with a real coil system is studied so as to simulate both acceleration and deceleration of spaceships

Ce travail présente le développement d’un robot exosquelette du membre supérieur pour des applications expérimentales dans le domaine des neurosciences. Le premier chapitre présente une description générale de l’anatomie du bras humain et introduit les principaux mouvements de l’épaule, du coude, et du poignet. Puis, l’état de l’art en matière d’exosquelettes et leurs différentes applications, fonctionnalités et limitations sont dressés. Le deuxième chapitre traite la conception mécanique et la plateforme électronique de notre prototype. Le calibrage et le traitement des signaux de commande et des retours codeurs sont abordés. Les modèles géométriques et cinématiques ainsi que les modèles dynamiques théoriques du robot sont calculés, simulés, et validés. Dans le troisième chapitre, la procédure d’identification des paramètres dynamiques de base du robot est présentée. Elle permet d’aboutir à une estimation du modèle dynamique réel utilisé dans la commande de l’exosquelette. Ensuite, une nouvelle méthode pour la compensation de gravité du robot est développée et validée, elle offre une alternative de commande plus simple et plus robuste et permet d’exécuter des manipulations dans un mode passif et transparent. Dans le dernier chapitre, la commande de l’exosquelette est abordée, trois stratégies de commande sont présentées, testées, et comparées. Une commande basée sur la compensation de la gravité et des frottements s’est avérée particulièrement appropriée pour nos manipulations. Puis, un protocole expérimental est mis au point pour un échantillon de douze personnes. Il permet l’évaluation des habilités visuelles et proprioceptives de l’homme à reconnaitre explicitement et implicitement ses propres mouvements reconstruits parmi d’autres. Enfin, une analyse statistique exhaustive des résultats est menée. Elle met en évidence une discrimination implicite entre les mouvements de soi et d’autrui, traduite par un avantage substantiel dans la reconnaissance des spécificités des mouvements reconstruits de soi par rapport à d’autrui. / This work presents the development of an upper extremity exoskeleton for experimental applications in the neuroscience field. The first chapter gives a general description of the anatomy of the human arm and introduces the major movements of the shoulder, elbow, and wrist joints. Then, the state of the art of exoskeletons and their different applications, features, and limitations are presented. The second chapter presents the mechanical design and the electronic platform our prototype. The calibration and signal processing procedures of the control and encoder feedback signals are discussed. The geometric, kinematic and dynamic models of the robot are calculated, simulated and validated. In the third chapter, the identification of the dynamic parameters of the robot is treated. It leads to an estimate of the real dynamic model employed in the control of the exoskeleton. Then, a new method for the gravity compensation of serial robots is developed and validated. It offers a simple and robust control alternative and the possibility to operate in a passive and transparent mode. In the last chapter, the control of the exoskeleton is addressed, three control strategies are presented, tested and compared. A control based on the gravity and friction compensation was particularly appropriate for our applications. Then, an experimental protocol is developed and applied on a sample of twelve persons. It allows the evaluation of the visual and proprioceptive abilities of humans to explicitly or implicitly recognize their own movements. Finally, an exhaustive statistical analysis of the results is conducted. It gives substantial evidence of an implicit discrimination between self and others’ movements manifested by a clear advantage in the recognition of the specificities of ones own movements reconstructed among others.