Thesis. 1977. Ph.D.--Massachusetts Institute of Technology. Dept. of Psychology. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND HUMANITIES. / Vita. / Includes bibliographies. / by Marc H. Raibert. / Ph.D.

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Introduction: Persons with Parkinson’s disease (PD) experience changes cortically, subcortically and behaviorally. This dissertation examines the asymmetry of motor behavior to explore the role of asymmetry in persons with PD and its connection to clinical symptoms. Purpose: Project 1: To assess the hand asymmetry difference in young adults versus older adults. Project 2: To investigate the difference in hand asymmetry in older adults and persons with PD. Project 3: To explore the correlation between function and clinical symptoms of persons with PD. Methods: 55 right-handed participants [Young Adults (YA) = 20, Female = 10; Older Adults (OA) = 20, Female = 10; Persons with PD = 15, Female = 5] were recruited and performed motor tasks: Purdue Pegboard test, grip strength test, response task, thumb opposition task, tapping task, three variations of timed-up-and-go test (TUG), single leg stance task (SLS), Weight Distribution test and Limits of Stability test. The two-way ANOVA was conducted to examine a variance between YA and OA. A separate two-way ANOVA was conducted comparing variance between OA and persons with PD. The purpose was to explore asymmetries, characterized by a significant difference between groups’ left and right sides. Pearson’s correlation was implemented to examine connection of clinical symptoms and motor behavior. Statistics: IBM SPSS 24 software was used. Two 2-way ANOVAs with the between group factor of group (Young vs. Older in Project 1; Older vs. PD in project 2), and within group factor of hand (Right vs. Left in Study 1 & Study 2) were used to examine if age (or PD) changes hand asymmetry. Pearson’s correlation coefficient was used to determine correlations between Unified Parkinson’s Disease Rating Scale (UPDRS) and motor tasks in PD patients (Study 3). Results: Project 1: Results indicate asymmetry reduces with age in fine motor tasks containing speed, dexterity and strength components. Project 2: The basal ganglia dysfunction does not overall further exacerbate the reduced asymmetry with age. Project 3: Clinical symptoms of PD measured by the UPDRS are generally not associated with fine motor tasks of this study.

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A conflicted and contentious literature has emerged from the proposal that visuospatial information from static images can automatically trigger associated motor representations. Curiously, investigations into this visual-motor relationship have predominantly focused on images of manipulable objects, while relatively little work has made use of images of body parts- whose referents are represented directly in the motor system. Limited work has made use of hand images as task-irrelevant primes, in an effort to determine whether a hand image automatically evokes a motor representation of the viewer’s corresponding limb. The results of these studies have provided diverging evidence and have resulted in competing theoretical accounts. Here, I present results from a series of stimulus-response compatibility experiments that were designed to probe the nature of representations generated by static hand images, while also addressing potential methodological weaknesses of the previous works. The results show that both stimulus properties and task demands influence the way in which an image of a hand is coded. Notably, I provide clear evidence that motor representations can be evoked automatically by depictions of particular hand postures, but that these representations are not an automatic, ineluctable component of the general processing of any hand image. These results not only contribute to a more unified account of hand representations, but also have wider implications for our understanding of the conditions under which static displays can engage motor representations. / Graduate

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This thesis presents a unified nonlinear optimization based speed and position estimation method in position sensorless control of interior permanent magnet synchronous motor (IPMSM) drives at wide speed range including standstill. The existing electromotive force (EMF) based sensorless methods are suitable for medium and high speed operation, but they can't be applied at low speed and standstill condition due to the reduced EMF values. The conventional saliency tracking based sensorless methods usually employ the continuous voltage or current injection at low speed including standstill condition. However, these methods degrade at high speed by introducing higher loss and torque ripples caused by the injection. Additionally, the initial rotor position needs to be detected at the machine startup to avoid the reverse rotation and to guarantee the delivery of the expected torque. Therefore, different position estimation techniques need to be combined in the controller at wide speed range, which increases the control system complexity. Hence, a unified nonlinear optimization based speed and position estimation method is proposed. At startup and standstill conditions, three steps are employed for initial position estimation. Step I employs pulse voltage injection in the stationary reference frame and a cost function which contains the knowledge of initial rotor position. The rotor position can be estimated by minimizing the cost function with injected voltage and induced current. Since the estimation results in Step I have an ambiguity of 180 degree, a generalized approach to magnetic polarity detection which exploits asymmetries in machine specific differential inductance profiles is employed as Step II. In order to improve the estimation accuracy, continuous sinusoidal voltage is injected in estimated rotor reference frame in Step III. A modified cost function is minimized based on the injected voltage and resulting current. At running state, cost functions which employ both speed and position as decision variables are proposed and utilized for estimation. The speed and position estimation can be delivered by minimizing the proposed cost functions based on the measurements of the stator voltage and current. Since only one position estimator exists in the drive system, the speed and position estimation is unified at wide speed range. The feasibility of the proposed estimation algorithms is validated with the prototype 5 KW IPMSM drives test bench. In order to benchmark the proposed estimation method, the performance of the proposed method was compared with existing sensorless control methods on the same prototype IPMSM drives test bench. Under the same test conditions, the proposed method outperforms with improved transient performance and steady state accuracy. Moreover, the proposed method is capable of delivering estimation with different voltage injection types and involving the nonlinear motor parameters, which makes this method more flexible in practice. Additionally, the capability of estimating speed and position with low sampling frequency also makes the application of the proposed method promising in high power AC motor drive systems. / Thesis / Doctor of Philosophy (PhD)

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