Publications
Gait Analysis Using Pervasive Motion Tracking and Mechanomyography Fusion
R Woodward, S Shefelbine, R Vaidyanathan
IEEE Transactions on Mechatronics
DOI: 10.1109/TMECH.2017.2715163
Publication Year: 2017 , Page(s): 12 pp vol.
Tags: Gait Analysis, Wearable Sensors, Mechanomyography, Inertial Measurement Unit, Pervasive Monitoring, Heterogeneous Sensing
Journal Article
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Muscle activity and human motion are useful parameters to map the diagnosis, treatment, and rehabilitation of neurological and movement disorders. In laboratory and clinical environments, electromyography (EMG) and motion capture systems enable the collection of accurate, high resolution data on human movement and corresponding muscle activity. However, controlled surroundings limit both the length of time and the breadth of activities that can be measured. Features of movement, critical to understanding patient progress, can change during the course of a day and daily activities may not correlate to the limited motions examined in a laboratory. We introduce a system to measure motion and muscle activity simultaneously over the course of a day in an uncontrolled environment with minimal preparation time and ease of implementation that enables daily usage. Our system combines a bespoke inertial measurement unit (IMU) and mechanomyography (MMG) sensor, which measures the mechanical signal of muscular activity. The IMU can collect data continuously, and transmit wirelessly, for up to 10 hours. We describe the hardware design and validation and outline the data analysis (including data processing and activity classification algorithms) for the sensing system. Furthermore, we present two pilot studies to demonstrate utility of the system, including activity identification in six able-bodied subjects with an accuracy of 98%, and monitoring motion/muscle changes in a subject with cerebral palsy and of a single leg amputee over extended periods (~5 hours). We believe these results provide a foundation for mapping human muscle activity and corresponding motion changes over time, providing a basis for a range of novel rehabilitation therapies.

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Telehealth, Wearable Sensors, and the Internet: Will They Improve Stroke Outcomes Through Increased Intensity of Therapy, Motivation, and Adherence to Rehabilitation Programs?
Burridge JH, Lee ACW, Turk R, Stokes M, Whitall J, Vaidyanathan R, Clatworthy P, Hughes AM, Meagher C, Franco E, Yardley L
Journal of Neurologic Physical Therapy
DOI: 10.1097/NPT.0000000000000183
Publication Year: 2017 , Page(s): S32-S38 vol.41
Tags: Rehabilitation, Wearable Sensors, Muscle Myography, Stroke, Telehealth
Journal Article
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BACKGROUND AND PURPOSE:

Stroke, predominantly a condition of older age, is a major cause of acquired disability in the global population and puts an increasing burden on health care resources. Clear evidence for the importance of intensity of therapy in optimizing functional outcomes is found in animal models, supported by neuroimaging and behavioral research, and strengthened by recent meta-analyses from multiple clinical trials. However, providing intensive therapy using conventional treatment paradigms is expensive and sometimes not feasible because of social and environmental factors. This article addresses the need for cost-effective increased intensity of practice and suggests potential benefits of telehealth (TH) as an innovative model of care in physical therapy.

SUMMARY OF KEY POINTS:

We provide an overview of TH and present evidence that a web-supported program, used in conjunction with constraint-induced therapy (CIT), can increase intensity and adherence to a rehabilitation regimen. The design and feasibility testing of this web-based program, "LifeCIT," is presented. We describe how wearable sensors can monitor activity and provide feedback to patients and therapists. The methodology for the development of a wearable device with embedded inertial and mechanomyographic sensors, algorithms to classify functional movement, and a graphical user interface to present meaningful data to patients to support a home exercise program is explained.

RECOMMENDATIONS FOR CLINICAL PRACTICE:

We propose that wearable sensor technologies and TH programs have the potential to provide most-effective, intensive, home-based stroke rehabilitation.

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A Wearable Automated System to Quantify Parkinsonian Symptoms Enabling Closed Loop Deep Brain Stimulation
P. Angeles, M. Mace, M. Admiraal, E. Burdet, N. Pavese, and R. Vaidyanathan
Towards Autonomous Robotic Systems
DOI: 10.1007/978-3-319-40379-3_2
Publication Year: 2016 , Page(s): 8-19 vol.9716
Tags: Parkinson
Conference Proceedings
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This study presents (1) the design and validation of a wear- able sensor suite for the unobtrusive capture of heterogeneous signals indicative of the primary symptoms of Parkinson’s disease; tremor, bradykinesia and muscle rigidity in upper extremity movement and (2) a model to characterise these signals as they relate to the symptom sever- ity as addressed by the Movement Disorder Society Unified Parkinson’s Disease Rating Scale (MDS-UPDRS).

The sensor suite and detection algorithms managed to distinguish between the non-mimicked and mimicked MDS-UPDRS tests on healthy subjects (p ≤ 0.15), for all the primary symptoms of Parkinson’s disease. Future trials will be conducted on Parkinsonian subjects receiving deep brain stimulation (DBS) therapy. Quantifying symptom severity and cor- relating severity ratings with DBS treatment will be an important step to fully automate DBS therapy.

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Fetal movements as a predictor of health
J Lai, N Nowlan, R Vaidyanathan, C J Shaw, C C Lees
Acta Obstetricia et Gynecologica Scandinavica (AOGS),
DOI: 10.1111/aogs.12944
Publication Year: 2016 , Page(s): 968-75 vol.95 (9)
Tags: Fetal Movement, Prenatal Health, Wearable Sensors, Ultrasound
Journal Article
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The key determinant to a fetus maintaining its health is through adequate perfusion and oxygen transfer mediated by the functioning placenta. When this equilibrium is distorted, a number of physiological changes, including reduced fetal growth, occur to favor survival. Technologies have been developed to monitor these changes with a view to prolong intrauterine maturity while reducing the risks of stillbirth. Many of these strategies involve complex interpretation, for example Doppler ultrasound for fetal blood flow and computerized analysis of fetal heart rate changes. However, even with these modalities of fetal assessment to determine the optimal timing of delivery, fetal movements remain integral to clinical decision-making. In high-risk cohorts with fetal growth restriction, the manifestation of a reduction in perceived movements may warrant an expedited delivery. Despite this, there has been little evolution in the development of technologies to objectively evaluate fetal movement behavior for clinical application. This review explores the available literature on the value of fetal movement analysis as a method of assessing fetal wellbeing, and demonstrates how interdisciplinary developments in this area may aid in the improvement of clinical outcomes.

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Movement decoding using neural synchronisation and inter-hemispheric connectivity from deep brain local field potentials
K Mamun, M Mace, M Lutman, J Stein, X Liu, T Aziz, R Vaidyanathan, S Wang
Journal of Neural Engineering
DOI: http://iopscience.iop.org/article/10.1088/1741-2560/12/5/056011/meta
Publication Year: 2015 , Page(s): 1-18 vol.12
Tags: Brain-Robot Interface, Local Field Potential, Grasp Control, Neural Recording
Journal Article
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Correlating electrical activity within the human brain to movement is essential for developing and refining interventions (e.g. deep brain stimulation (DBS)) to treat central nervous system disorders. It also serves as a basis for next generation brain–machine interfaces (BMIs). This study highlights a new decoding strategy for capturing movement and its corresponding laterality from deep brain local field potentials (LFPs). Approach. LFPs were recorded with surgically implanted electrodes from the subthalamic nucleus or globus pallidus interna in twelve patients with Parkinson's disease or dystonia during a visually cued finger-clicking task. We introduce a method to extract frequency dependent neural synchronization and inter-hemispheric connectivity features based upon wavelet packet transform (WPT) and Granger causality approaches. A novel weighted sequential feature selection algorithm has been developed to select optimal feature subsets through a feature contribution measure. This is particularly useful when faced with limited trials of high dimensionality data as it enables estimation of feature importance during the decoding process. Main results. This novel approach was able to accurately and informatively decode movement related behaviours from the recorded LFP activity. An average accuracy of 99.8% was achieved for movement identification, whilst subsequent laterality classification was 81.5%. Feature contribution analysis highlighted stronger contralateral causal driving between the basal ganglia hemispheres compared to ipsilateral driving, with causality measures considerably improving laterality discrimination. Significance. These findings demonstrate optimally selected neural synchronization alongside causality measures related to inter-hemispheric connectivity can provide an effective control signal for augmenting adaptive BMIs. In the case of DBS patients, acquiring such signals requires no additional surgery whilst providing a relatively stable and computationally inexpensive control signal. This has the potential to extend invasive BMI, based on recordings within the motor cortex, by providing additional information from subcortical regions.

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Multi-modal locomotion: from animal to application
Lock, R. J., Burgess, S. C., Vaidyanathan, R.
Bioinspiration and Biomimetics
DOI: 10.1088/1748-3182/9/1/011001
Publication Year: 2014 , Page(s): 1-18 vol.9
Tags: Animals, Biomimetics/*instrumentation/*methods, Equipment Design, Gait/*physiology, Humans, Locomotion/*physiology, *Models, Biological, Robotics/*instrumentation/*methods
Journal Article
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The majority of robotic vehicles that can be found today are bound to operations within a single media (i.e. land, air or water). This is very rarely the case when considering locomotive capabilities in natural systems. Utility for small robots often reflects the exact same problem domain as small animals, hence providing numerous avenues for biological inspiration. This paper begins to investigate the various modes of locomotion adopted by different genus groups in multiple media as an initial attempt to determine the compromise in ability adopted by the animals when achieving multi-modal locomotion. A review of current biologically inspired multi-modal robots is also presented. The primary aim of this research is to lay the foundation for a generation of vehicles capable of multi-modal locomotion, allowing ambulatory abilities in more than one media, surpassing current capabilities. By identifying and understanding when natural systems use specific locomotion mechanisms, when they opt for disparate mechanisms for each mode of locomotion rather than using a synergized singular mechanism, and how this affects their capability in each medium, similar combinations can be used as inspiration for future multi-modal biologically inspired robotic platforms.

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A Bio-Inspired Condylar Hinge for Robotic Limbs
Etoundi, A. C.Burgess, S. C., Vaidyanathan, R.,
Journal of Mechanisms and Robotics-Transactions of the Asme
DOI: 10.1115/1.4024471
Publication Year: 2013 , Page(s): 1-8 vol.5
Tags: knee-joint, design, mechanism, flexion, ligaments, movement
Journal Article
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This paper presents a novel condylar hinge for robotic limbs which was inspired by the human knee joint. The ligaments in the human knee joint can be modeled as an inverted parallelogram four-bar mechanism. The knee joint also has a condylar cam mechanism between the femur and tibia bones. The bio-inspired joint mimics the four-bar mechanism and the cam mechanism of the human knee joint. The bio-inspired design has the same desirable features of a human knee joint including compactness, high mechanical advantage, high strength, high stiffness and locking in the upright position. These characteristics are important for robotic limbs where there are often tight space and mass limitations. A prototype hinge joint similar in size to the human knee joint has been designed and tested. Experimental tests have shown that the new condylar hinge joint has superior performance to a pin-jointed hinge in terms of mechanical advantage and stiffness. The prototype hinge has a mechanical advantage that is greater than a pin-jointed hinge by up to 35% which leads to a corresponding reduction in the peak force of the actuator of up to 35% for a squatting movement. The paper also presents a five-step design procedure to produce a combined inverted parallelogram mechanism with a cam mechanism.
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A Reflexive Control Architecture based on a Neural Model of the Cockroach Escape Response
R. Vaidyanathan, C. Chen, C. D. Jeong, C. Williams, R.E. Ritzmann, R.D Quinn.
Journal of Systems and Control Engineering
DOI: http://journals.sagepub.com/doi/abs/10.1177/0959651811428035
Publication Year: 2012 , Page(s): 699-718 vol.226
Tags: Autonomous Control, Bio-inspired Control
Journal Article
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This paper presents a biologically inspired architecture for rapid real-time control of autonomous or semi-autonomous vehicles based on a neural model of the escape response of the American cockroach, Periplaneta americana.  The architecture fuses exteroceptive and proprioceptive inputs in a manner similar to the insect to produce commands for collision avoidance and, in some cases, orientation for target strike.  It functions as a reflexive subsystem that integrates smoothly with higher-level planning and behavioral control systems.  The performance of the reflex is demonstrated in simulation and in hardware experiments on both air and ground vehicles, even in the presence of noisy, false or disruptive sensor data.  (AWARDED: BEST PAPER IN JOURNAL, 2012)

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Spray deposited multilayered dielectric elastomer actuators
Araromi, O. A., Conn, A. T., Ling, C. S., Rossiter, J. M., Vaidyanathan, R., Burgess, S. C.
Sensors and Actuators a-Physical
DOI: 10.1016/j.sna.2011.03.004
Publication Year: 2011 , Page(s): 459-467 vol.167
Tags: dielectric elastomer, electroactive , polymers (eaps), unimorph actuators, spray deposition, dea fabrication, figure of merit
Journal Article
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Dielectric elastomer electroactive polymers are an emerging class of actuation technology which is inherently compliant and capable of large actuation stresses and strains. Despite promising performance characteristics, their fabrication has been inhibited by two significant factors: (i) the requirement for consistently thin dielectric layers, to minimise activation voltages; (ii) automated production of multilayered configurations, to increase the actuation power. This paper presents a robust, low-cost fabrication technique that overcomes these issues by utilising optimised spray deposition. Spray deposition of silicone dielectric elastomer actuators (DEAs) offers numerous benefits including scalability, flexibility for different DEA configurations and multilayered assembly with a high degree of automation. A predictive model based on the Gaussian distribution is used to characterise the profile of deposited elastomer layers for principal fabrication parameters. This model enables individual dielectric layers to be composed from multiple parallel depositions, which greatly increases scalability as demonstrated by fabricated DEA films with planar dimensions from 25 mm(2) to over 10,000 mm(2). Using the predictive model, a new figure of merit is introduced for analyzing DEA film profiles by considering the estimated mean Maxwell stress that is feasible for a specific dielectric breakdown strength. The analysis suggests that compared to a single deposition, a film composed of four parallel depositions will increase the maximum characteristic DEA dimension by an order of magnitude, while producing a comparable mean Maxwell stress. A significant advantage of the presented spray deposition technique is the semi-automated layering process, creating stratified solid-state actuators. By eliminating the stacking of layers from the fabrication process, inherent electrical isolation, good layer-to-layer bonding and capacity for more complex 3D geometries is achieved. A proof-of-concept multilayer unimorph and stack DEA is presented to validate the fabrication technique through static and dynamic displacement tests.

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A Feature Ranking Strategy to Facilitate Multivariate Signal Classification
Gupta, L., Kota, S., Murali, S., Molfese, D. L., Vaidyanathan, R.
Ieee Transactions on Systems Man and Cybernetics Part C-Applications and Reviews
DOI: 10.1109/Tsmcc.2009.2024648
Publication Year: 2010 , Page(s): 98-108 vol.40
Tags: curse of dimensionality, discrete cosine transform (dct), ear-pressure signal classification, event-related potential (erp), classification, feature ranking ,human-machine interface (hmi), multivariate signal classification, principal component transform
Journal Article
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A strategy is introduced to rank and select principal component transform (PCT) and discrete cosine transform (DCT) transform coefficient features to overcome the curse of dimensionality frequently encountered in implementing multivariate signal classifiers due to small sample sizes. The criteria considered for ranking include the magnitude, variance, interclass separation, and classification accuracies of the individual features. The feature ranking and selection strategy is applied to overcome the dimensionality problem, which often plagues the implementation and evaluation of practical Gaussian signal classifiers. The applications of the resulting PCT- and DCT-Gaussian signal classification strategies are demonstrated by classifying single-channel tongue-movement ear-pressure signals and multichannel event-related potentials. Through these experiments, it is shown that the dimension of the feature space can be decreased quite significantly by means of the feature ranking and selection strategy. The ranking strategy not only facilitates overcoming the dimensionality curse for multivariate classifier implementation but also provides a means to further select, out of a rank-ordered set, a smaller set of features that give the best classification accuracies. Results show that the PCT- and DCT-Gaussian classifiers yield higher classification accuracies than those reported in previous classification studies on the same signal sets. Among the combinations of the two transforms and four feature selection criteria, the PCT-Gaussian classifiers using the maximum magnitude and maximum variance selection criteria gave the best classification accuracies across the two sets of classification experiments. Most noteworthy is the fact that the multivariate Gaussian signal classifiers developed in this paper can be implemented without having to collect a prohibitively large number of training signals simply to satisfy the dimensionality conditions. Consequently, the classification strategies can be beneficial for designing personalized human-machine interface signal classifiers for individuals from whom only a limited number of training signals can reliably be collected due to severe disabilities.

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