A design for a novel tubular high-precision direct-drive brushless linear motor has been developed. The novelty of the design lies in the orientation of the magnets in the mover. In conventional linear motors the magnets of the armature are arranged such that the attractive poles are adjacent throughout, in an NS-NS-NS orientation, where N denotes the north pole and S denotes the south pole of the magnet. In the new design, the magnets in the moving part are oriented in an NS-NS-SN-SN orientation. This change in orientation yields greater magnetic field intensity near the like-pole region. The magnets of the mover are encased within a brass tube, which slides through a three-phase array of current-carrying coils. As the coils are powered, they induce a force on the permanent magnets according to the Lorentz force equation. The primary advantages of the motor are its compact nature, fast, precise positioning due to its low-mass moving part, direct actuation, extended travel range, and ability to extend beyond its base. The linear motor is used in conjunction with a position sensor, power amplifiers, and a controller to form a complete solution for positioning and actuation requirements. Controllers were developed for two applications, with a lead-lag as the backbone of each. For the first application, the principal requirements are for fast rise and settling times. For the second application, the primary requirement is for near-zero overshoot. With the controller for application 1, the motor has a rise time of 55 ms, a settling time of 600 ms, and 65% overshoot. With the controller for application 2 implemented, the motor has a rise time of 1 s, a settling time of 2.5 s, and 0.2% overshoot. The maximum force capability of the motor is measured to be 26.4 N. The positioning resolution is 35 ?m. This thesis discusses the motor's physical design, construction, implementation, testing, and tuning. It includes specifications of the components of the motor and other necessary equipment, desired and actual motor performance, and the primary limitations on the precision of the system.

Damage to motor areas of the brain, caused by stroke, can produce devastating motor deficits, including aberrant control of force. After stroke, reorganization of the brain’s motor system has been identified as one of the fundamental mechanisms involved in recovery of motor control after stroke. Yet, few studies have investigated how force production and modulation are encoded in the brain after stroke and how this relates to motor outcome. Thus, the purpose of this study was to (1) understand how past neuroimaging literature has contributed to establishing common patterns of brain reorganization during both relative and absolute force production after stroke, (2) examine how brain function is reorganized during force production and modulation in individuals with stroke, and (3) relate this task-related reorganization of brain function to the amount of paretic arm use after stroke. In the second chapter, we systematically reviewed all relevant literature examining brain activation during force production after stroke. The following chapters (chapters 3 and 4) applied functional magnetic resonance imaging (fMRI) to examine the neural correlates of force production and modulation after stroke. Chapter 2 supports differences in task-related brain activation dependent on features of stroke, such as severity and chronicity, as well as influence of rehabilitation. In addition, results suggest that activation of common motor areas of the brain during force production can be identified in relation to functional outcome after stroke. Results from the subsequent two chapters (3 and 4), demonstrate that brain function reorganizes in terms of absolute, and not relative force production after stroke. Specifically, stroke participants exhibit greater activation of motor areas than healthy controls when matched for absolute force production. Moreover, there is a relationship between paretic arm usage and brain activation, where stroke participants having less paretic arm use, as measured using wrist accelerometers, exhibit higher brain activation. Results of this thesis suggest that during absolute force production, brain activation may approach near maximal levels in stroke participants at lower forces than healthy controls. Furthermore, this effect may be amplified even further in subjects with less paretic arm usage, as increased activation in motor areas occurs in participants with less arm use after stroke. Ultimately, the results from this thesis will contribute to research relevant to brain reorganization in individuals with stroke and may lead to the development of new, beneficial therapeutic interventions that optimize brain reorganization and improve functional recovery after stroke.

A novel toroidal pneumatic motor (rotary actuator or rotary engine) has been developed and tested. The motor is designed with a ring torus (or revolved circular cross-section) working chamber, which is formed by two rotors and sections of a casing (or stator). The rotors are designed with an equal number of pistons, an arrangement of one-way bearings (to transfer torque from the rotors to a common drive shaft), and an impact mechanism to operably control the positioning of the rotors relative to ports located within the stationary casing. This design is aimed at improving the power density (power per unit mass), efficiency and torque output at low shaft speeds, when compared to conventional vane motors. Dynamometer test results are presented, showing the torque output of the motor with compressed air supply pressures of 10 to 80 psi at 10 psi increments.

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Numerous studies have investigated motor learning by examining the adaptation of reaching movements to visuomotor perturbations that alter the mapping between actual and visually perceived hand position. The picture of the visuomotor transformation from visual input to motor input that has developed consists of three broad phases: integration of hand and target locations in a common reference frame, calculation of a movement vector between hand and target, and transformation of this movement vector from the common reference frame into motor commands. The process of adapting to a visuomotor rotation is generally viewed as an alteration of the vectorial representation of reach planning. When visual feedback is rotated, the motor and visual directions no longer coincide and the motor command executed is remapped to the subsequent visual direction produced. In the current set of studies, we examined how learning a visuomotor rotation while reaching to a target with a curved hand path generalizes to straight path reaching and novel target directions. We found that there is very little to no generalization of learning between curved reaches and straight reaches when given only endpoint feedback. With continuous visual feedback, we found partial transfer. This suggests that in the absence of visual feedback, the vectorial adaptation hypothesis is insufficient and adaptation to a visuomotor rotation is mediated by the later stages of the visuomotor transformation, when the motor commands specific to the hand path used are being generated. / Thesis (Master, Psychology) -- Queen's University, 2009-04-16 15:42:40.872

The ability to safely react to dangerous situations, or exploit opportunities within a dynamically changing world is fundamental for our survival. In order to respond to such changes in the environment, sensory information must first be received and processed by the nervous system before an appropriate motor response can be planned and executed. However, relatively little is known about how the central nervous system computes such sensory to motor transformations that are so critical for guiding efficient behavior. This thesis explores some of the neural mechanisms that underlie the visuomotor transformations that guide eye movements. Specifically, this thesis studied saccades (rapid eye movements critical for visual orienting in primates) and examined the relationships between visual and motor signals in the primate Superior Colliculus (SC, a midbrain structure located at the nexus between visual input and motor output that is critical for visual orienting). I recorded extracellular action potentials (spikes) from single neurons related to: 1) the appearance of visual saccade targets; 2) saccade planning and preparation; and 3) the execution of precise saccades that orient to visual targets. In this thesis I present four studies that examine the relationships between visual and motor related responses in the SC during visually guided saccades. In chapter 2 I examined the alignment between visual and motor response fields and concluded that they were well aligned. In chapters 3 and 4 I explored how visual responses were modulated by stimulus intensity and how this modulation influenced saccade behavior. I concluded that luminance modulated multiple properties of the visual response including the timing and maximum discharge rate and these changes were highly correlated to changes in saccade latency and metrics. In the fifth chapter I applied some of the knowledge gained from the previous chapters to develop a neural network model of the SC that was capable of simulating saccadic sensory to motor transformations and predict saccadic reaction time. I concluded that saccade latency was strongly dependant on the spatial interactions of visual and saccade related signals in the SC. Together, these findings provide novel insight into the neural mechanisms underlying saccadic sensorimotor transformations. / Thesis (Ph.D, Neuroscience Studies) -- Queen's University, 2011-03-03 08:36:14.559

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