Computer Games for Motor Speech Rehabilitation

This research investigates the problem of creating a system for interactive digital visual feedback of articulator kinematics measures for speech rehabilitation. Recent technology provides precise non-line-of-sight positional tracking of small sensors which affords exploration into the motion of articulators such as the tongue. By utilizing recent game development technology, articulation kinematics can be visualized in realtime. Using these technologies the basis for an interactive rehabilitation system is formed. The system is posed as both a research apparatus and a potential clinical rehabilitation delivery system. As such, this system provides an extensible software and design architecture for the creation of interactive feedback visualizations and kinematic speech metrics as well as a clinical research front end for the creation and delivery of speech motor rehabilitation protocols

Experimental Kinematic Analysis of Cadaver Knees Using a Knee Simulator and Surgical Navigation System

The objective of this thesis was to develop and implement a methodology to enable knee kinematics to be studied during an in vitro simulated squat. As an application of the methodology, it was used to examine the null hypothesis that a knee with a posterior cruciate ligament (PCL) retaining total knee arthroplasty (TKA) would show no differences in kinematics compared with a PCLsacrificing TKA. A surgical navigation system was used in combination with a knee simulator, and algorithms were developed to calculate knee kinematics from motion capture data and bone and implant landmarks. The methodology employed in this study produced kinematics for two knees obtained post-mortem from two primary TKAsubjects. The results demonstrated differences in kinematics between the two knees with different TKA designs that were corroborated by published in vitro and vivo studies of the same implant designs

Design and Validation of a Portable Wireless Data Acquisition System for Measuring Human Joint Angles in Medical Applications

A prototype sensor system to capture and measure human joint movements in medical applications was developed. An algorithm that uses measurements from two IMU sensors to estimate the angle of one human joint was developed. Custom-made hardware and software were developed. Validation results showed 0.67° maximum error in static condition, 1.56° maximum RMSE for dynamic measurements and 2.5° average error during fast movements’ tests. The prototype has been successfully used by medical teams

Validation of machine vision and action sport cameras for 3D motion analysis model reconstruction

The study investigated the feasibility of using action sport cameras for motion analysis research. Data acquired from two different marker-based motion capture systems and six different camera combinations were analyzed for motion reconstruction accuracy. Two different calibration procedures were used to determine the influence on marker position reconstruction. Static and dynamic calibration mean merit score differences between the reference and experimental camera systems were 0.4 mm and 1.3 mm, respectively. Angular displacement difference between the reference and experimental camera systems range between 0.1 and 2.0 degrees. A systematic bias (− 0.54 to 0.19 degrees) was determined between the reference and the experimental camera systems for range of motion. The mean of the multi-trial findings suggests the machine vision camera system calibrated with a dynamic procedure generated highly accurate three-dimensional reconstructed ROM data (0.5 degree) followed closely by the four action sport cameras implementing a static calibration procedure (0.5 degree). The overall findings suggest the selected machine vision and action sport camera systems produced comparable results to the reference motion analysis system. However, the combination of camera type, processing software, and calibration procedure can influence motion reconstruction accuracy

Spin correlations in p⃗p⃗→pnπ+\vec{p}\vec{p}\to pn\pi^{+} pion production near threshold

A first measurement of longitudinal as well as transverse spin correlation coefficients for the reaction $\vec{p}\vec{p}\to pn\pi^+$ was made using a polarized proton target and a polarized proton beam. We report kinematically complete measurements for this reaction at 325, 350, 375 and 400 MeV beam energy. The spin correlation coefficients $A_{xx}+A_{yy}, A_{xx}-A_{yy}, A_{zz}, A_{xz},$ and the analyzing power $A_{y},$ as well as angular distributions for $\sigma(\theta_{\pi})$ and the polarization observables $A_{ij}(\theta_{\pi})$ were extracted. Partial wave cross sections for dominant transition channels were obtained from a partial wave analysis that included the transitions with final state angular momenta of $l\leq 1$. The measurements of the ${\vec{p}\vec{p}\to pn\pi^{+}}$ polarization observables are compared with the predictions from the J\"ulich meson exchange model. The agreement is very good at 325 MeV, but it deteriorates increasingly for the higher energies. At all energies agreement with the model is better than for the reaction ${\vec{p}\vec{p}\to pp\pi^{0}}$.Comment: Preprint, 21 pp, submitted to Phys. Rev. C. Keywords: Mesons, Polarization, Spin Correlations, Few body system

A low-cost confocal microscope for the undergraduate lab

We demonstrate a simple and cost-efficient scanning confocal microscope setup for use in advanced instructional physics laboratories. The setup is constructed from readily available commercial products, and the implementation of a 3D-printed flexure stage allows for further cost reduction and pedagogical opportunity. Experiments exploring the thickness of a microscope slide and the surface of solid objects with height variation are presented as foundational components of undergraduate laboratory projects, and demonstrate the capabilities of a confocal microscope. This system allows observation of key components of a confocal microscope, including depth perception and data acquisition via transverse scanning, making it an excellent pedagogical resource

Machine Learning for Optical Motion Capture-driven Musculoskeletal Modelling from Inertial Motion Capture Data

Marker-based Optical Motion Capture (OMC) systems and associated musculoskeletal (MSK) modelling predictions offer non-invasively obtainable insights into in vivo joint and muscle loading, aiding clinical decision-making. However, an OMC system is lab-based, expensive, and requires a line of sight. Inertial Motion Capture (IMC) systems are widely-used alternatives, which are portable, user-friendly, and relatively low-cost, although with lesser accuracy. Irrespective of the choice of motion capture technique, one needs to use an MSK model to obtain the kinematic and kinetic outputs, which is a computationally expensive tool increasingly well approximated by machine learning (ML) methods. Here, we present an ML approach to map experimentally recorded IMC data to the human upper-extremity MSK model outputs computed from ('gold standard') OMC input data. Essentially, we aim to predict higher-quality MSK outputs from the much easier-to-obtain IMC data. We use OMC and IMC data simultaneously collected for the same subjects to train different ML architectures that predict OMC-driven MSK outputs from IMC measurements. In particular, we employed various neural network (NN) architectures, such as Feed-Forward Neural Networks (FFNNs) and Recurrent Neural Networks (RNNs) (vanilla, Long Short-Term Memory, and Gated Recurrent Unit) and searched for the best-fit model through an exhaustive search in the hyperparameters space in both subject-exposed (SE) & subject-naive (SN) settings. We observed a comparable performance for both FFNN & RNN models, which have a high degree of agreement (ravg, SE, FFNN = 0.90+/-0.19, ravg, SE, RNN = 0.89+/-0.17, ravg, SN, FFNN = 0.84+/-0.23, & ravg, SN, RNN = 0.78+/-0.23) with the desired OMC-driven MSK estimates for held-out test data. Mapping IMC inputs to OMC-driven MSK outputs using ML models could be instrumental in transitioning MSK modelling from 'lab to field'.Comment: 23 pages, 12 figures, 5 table

IMU Validation Apparatus for Human Joints

ME450 Capstone Design and Manufacturing Experience: Fall 2020Inertial measurement units (IMUs) are small sensor packs that include accelerometers, gyroscopes, and magnetometers that are used to conduct movement analysis outside of a laboratory setting. IMUs use an integration process to determine absolute orientation and location of the object they are attached to, so error in their output is vulnerable to discrepancies from the effects of long-term data collection. Additional error can also be introduced through magnetic interference with the magnetometer readings. To combat this, calibration and post-processing algorithms can be made to adjust for these measurement errors, but ground truth angle data is needed to quantify their performance. This report outlines the requirements, specifications, evaluated concepts, verification methods, and developed solution for a device that is capable of measuring ground truth angles for comparison with angles derived from different IMU algorithms.Dr. Stephen Cain, Mechanical Engineering, University of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/164441/1/IMU_Validation_Apparatus_for_Human_Joints.pd

Visual perceptual skills and motor performance in gymnastics : the influence of task constraints

Esta dissertação teve como principal objetivo investigar a influência dos constrangimentos da tarefa nos comportamentos visual e motor de ginastas de nível elite. Para recolher dados dos comportamentos visual e motor num contexto ecológico representativo, foi validado um sistema de sensores inerciais para medir os ângulos articulares em 3D, durante uma tarefa gímnica. Três estudos foram realizados. O primeiro estudo investigou o comportamento visual durante a realização de quatro tarefas no mini trampolim e no mini-trampolim com mesa de saltos, aumentando progressivamente o nível de complexidade. O segundo estudo analisou a validade de um sistema de sensores inerciais na medição de ângulos articulares em 3D durante a realização de uma tarefa gímnica, utilizando um sistema optoelectrónico como referência. O estudo final examinou a influência dos constrangimentos da tarefa (presença e ausência da mesa de saltos) nos comportamentos visual e motor de ginastas de elite, durante a fase de corrida para o mini trampolim e mini-trampolim com mesa de saltos. O primeiro estudo sugeriu que os ginastas adaptaram o comportamento visual à complexidade da tarefa. O mini-trampolim foi a área de interesse mais fixada. O segundo estudo mostrou que o sistema de sensores inerciais apresentou boas correlações, erros aceitáveis e que não apresenta diferenças significativas para a maioria das articulações, comparando com o sistema optoelectrónico. O último estudo revelou que a presença da mesa de saltos influenciou o comportamento visual dos ginastas com menor expertise, enquanto que o comportamento motor foi diferentes nas duas tarefas para todos dos ginastas. Estas conclusões sugerem que o sistema de sensores inerciais é válido para fornecer dados cinemáticos aos treinadores e ginastas, e que os constrangimentos da tarefa influenciam o comportamento visual de ginastas de elite de forma distinta, consoante o nível de expertise.The main aim of this dissertation was to investigate the influence of task constraints on gaze and motor behaviours in elite gymnasts. To collect gaze and motor data in an ecological and representative context, an inertial measurement units system to measure 3D joint angles outside the laboratory was validated. To accomplish these goals, three studies were completed. In the first study, gaze behaviour was investigated during the performance of four gymnastics tasks on mini-trampoline and on mini-trampoline with vaulting table, while increasing the level of complexity. The second study analysed the validity of an inertial measurement units system in measuring 3D joint angles during a gymnastics task, using an optoelectronic system as a reference. The final study examined the influence of task constraint (i.e., presence and absence of vaulting table) on gaze and motor behaviours of elite gymnasts, during the approach run phase to the mini-trampoline and mini-trampoline with vaulting table. The first study showed that gymnasts adapted their gaze behaviours according to the level of complexity of the task and that the most fixated area of interest was the mini-trampoline. The second study demonstrated that the inertial measurement units system has very good and acceptable correlations, acceptable errors and no significant differences for the majority of the joint ankles. Finally, the last study revealed that the presence of the vaulting table influenced gaze behaviour only in elite gymnasts (compared to super-elite gymnasts), while different motor behaviours occurred across the two tasks, irrespective of gymnasts’ level of expertise. The findings indicate that the inertial measurement units system is valid to provide kinematics data, and task constraints (i.e., presence and absence of vaulting table) influence gaze behaviours of elite gymnasts differently, across varying levels of expertise