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https://www.readbyqxmd.com/read/28814011/adaptive-control-of-an-exoskeleton-robot-with-uncertainties-on-kinematics-and-dynamics
#1
Brahim Brahmi, Maarouf Saad, Cristobal Ochoa-Luna, Mohammad H Rahman
In this paper, we propose a new adaptive control technique based on nonlinear sliding mode control (JSTDE) taking into account kinematics and dynamics uncertainties. This approach is applied to an exoskeleton robot with uncertain kinematics and dynamics. The adaptation design is based on Time Delay Estimation (TDE). The proposed strategy does not necessitate the well-defined dynamic and kinematic models of the system robot. The updated laws are designed using Lyapunov-function to solve the adaptation problem systematically, proving the close loop stability and ensuring the convergence asymptotically of the outputs tracking errors...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28814002/joint-based-velocity-feedback-to-virtual-limb-dynamic-perturbations
#2
Eric J Earley, Kyle J Kaveny, Reva E Johnson, Levi J Hargrove, Jon W Sensinger
Despite significant research developing myoelectric prosthesis controllers, many amputees have difficulty controlling their devices due in part to reduced sensory feedback. Many attempts at providing supplemental sensory feedback have not significantly aided control. We hypothesize this is because the feedback provided contains redundant information already provided by vision. However, whereas vision provides egocentric, position-based feedback, sensory feedback tied to joint coordinates may provide information complementary to vision...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813997/dynamic-elasticity-measurement-for-prosthetic-socket-design
#3
Yujin Kim, Junghoon Kim, Hyeryon Son, Youngjin Choi
The paper proposes a novel apparatus to measure the dynamic elasticity of human limb in order to help the design and fabrication of the personalized prosthetic socket. To take measurements of the dynamic elasticity, the desired force generated as an exponential chirp signal in which the frequency increases and amplitude is maintained according to time progress is applied to human limb and then the skin deformation is recorded, ultimately, to obtain the frequency response of its elasticity. It is referred to as a Dynamic Elasticity Measurement Apparatus (DEMA) in the paper...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813929/soft-brain-machine-interfaces-for-assistive-robotics-a-novel-control-approach
#4
Lucia Schiatti, Jacopo Tessadori, Giacinto Barresi, Leonardo S Mattos, Arash Ajoudani
Robotic systems offer the possibility of improving the life quality of people with severe motor disabilities, enhancing the individual's degree of independence and interaction with the external environment. In this direction, the operator's residual functions must be exploited for the control of the robot movements and the underlying dynamic interaction through intuitive and effective human-robot interfaces. Towards this end, this work aims at exploring the potential of a novel Soft Brain-Machine Interface (BMI), suitable for dynamic execution of remote manipulation tasks for a wide range of patients...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813901/adaptive-control-based-on-an-on-line-parameter-estimation-of-an-upper-limb-exoskeleton
#5
Akram Riani, Tarek Madani, Abdelhafid El Hadri, Abdelaziz Benallegue
This paper presents an adaptive control strategy for an upper-limb exoskeleton based on an on-line dynamic parameter estimator. The objective is to improve the control performance of this system that plays a critical role in assisting patients for shoulder, elbow and wrist joint movements. In general, the dynamic parameters of the human limb are unknown and differ from a person to another, which degrade the performances of the exoskeleton-human control system. For this reason, the proposed control scheme contains a supplementary loop based on a new efficient on-line estimator of the dynamic parameters...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813879/interaction-force-and-motion-estimators-facilitating-impedance-control-of-the-upper-limb-rehabilitation-robot
#6
Aitziber Mancisidor, Asier Zubizarreta, Itziar Cabanes, Pablo Bengoa, Je Hyung Jung
In order to enhance the performance of rehabilitation robots, it is imperative to know both force and motion caused by the interaction between user and robot. However, common direct measurement of both signals through force and motion sensors not only increases the complexity of the system but also impedes affordability of the system. As an alternative of the direct measurement, in this work, we present new force and motion estimators for the proper control of the upper-limb rehabilitation Universal Haptic Pantograph (UHP) robot...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813876/design-control-and-validation-of-the-variable-stiffness-exoskeleton-flexo
#7
Sariah Mghames, Marco Laghi, Cosimo Della Santina, Manolo Garabini, Manuel Catalano, Giorgio Grioli, Antonio Bicchi
In this paper we present the design of a one degree of freedom assistive platform to augment the strength of upper limbs. The core element is a variable stiffness actuator, closely reproducing the behavior of a pair of antagonistic muscles. The novelty introduced by this device is the analogy of its control parameters with those of the human muscle system, the threshold lengths. The analogy can be obtained from a proper tuning of the mechanical system parameters. Based on this, the idea is to control inputs by directly mapping the estimation of the muscle activations, e...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813866/a-single-session-of-perturbation-based-gait-training-with-the-a-tpad-improves-dynamic-stability-in-healthy-young-subjects
#8
Dario Martelli, Jiyeon Kang, Sunil K Agrawal
Gait and balance disorders are among the most common causes of falls in older adults. Most falls occur as a result of unexpected hazards while walking. In order to improve the effectiveness of current fall-prevention programs, new balance training paradigms aim to strengthen the control of the compensatory responses required after external perturbations. The aim of this study was to analyze the adaptions of reactive and proactive strategies to control stability after repeated exposures to waist-pull perturbations delivered while walking...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813846/closed-loop-emg-informed-model-based-analysis-of-human-musculoskeletal-mechanics-on-rough-terrains
#9
C Varotto, Z Sawacha, L Gizzi, D Farina, M Sartori
This work aims at estimating the musculoskeletal forces acting in the human lower extremity during locomotion on rough terrains. We employ computational models of the human neuro-musculoskeletal system that are informed by multi-modal movement data including foot-ground reaction forces, 3D marker trajectories and lower extremity electromyograms (EMG). Data were recorded from one healthy subject locomoting on rough grounds realized using foam rubber blocks of different heights. Blocks arrangement was randomized across all locomotion trials to prevent adaptation to specific ground morphology...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813840/a-novel-protocol-to-evaluate-ankle-movements-during-reaching-tasks-using-pedianklebot
#10
Francesca Martelli, Eduardo Palermo, Stefano Rossi
The aim of the study is to design a novel protocol to characterize the ankle movements during dorsal and plantar flexion reaching tasks using the pediAnklebot. Five healthy children were instructed to control a pointer and hit targets appearing on the monitor, by moving their ankle alternatively up and down. The protocol consisted of 60 targets, 30 up and 30 down, reachable via dorsiflexion and plantarflexion movements, respectively. Ankle angular displacements and torques were gathered by encoders and load cells embedded in the robot...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813821/gait-training-assist-system-of-a-lower-limb-prosthetic-visualizing-muscle-activation-pattern-using-a-color-depth-sensor
#11
Kunihiro Ogata, Tomoki Mita, Toshiaki Tsuji, Yoshio Matsumoto
Some unilateral lower-limb amputees load the intact limb more than the prosthetic limb. This can cause chronic pains, fatigue, lumbago, and joint diseases, including knee osteoarthritis. To avoid and counteract these symptoms it is necessary to improve their asymmetric gait. Increasing the function of the hip abductor muscle is important to maintaining symmetrical weight distribution. Therefore, the purpose of this study is to develop a training assist system, which estimates and visualizes an abductor muscle by using a color-depth sensor...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813816/computational-rehabilitation-of-neglect-using-state-space-models-to-understand-the-recovery-mechanisms
#12
Giulia Sedda, Marcella Ottonello, Elena Fiabane, Caterina Pistarini, Anna Sedda, Vittorio Sanguineti
Unilateral spatial neglect is a neuropsychological syndrome often observed in right hemisphere stroke patients. The symptoms differ from subject to subject. A few rehabilitation approaches, e.g. prism adaptation, have demonstrated some effect in reducing the symptoms, but the underlying mechanisms are still largely unclear. Recently, neural models have been proposed to qualitatively describe cortical lesions, the resulting neglect symptoms and the effects of treatment. However, these predictions are qualitative and cannot be used to compare different hypotheses or to interpret symptoms at individual subjects level...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813789/simulating-the-impact-of-sensorimotor-deficits-on-reaching-performance
#13
Sean M Sketch, Cole S Simpson, Frederic Crevecoeur, Allison M Okamura
The healthy human nervous system accurately and robustly controls movements despite nonlinear dynamics, noise, and delays. After a stroke, motor ability frequently becomes impaired. To provide insight into the relative impact of specific sensorimotor deficits on motor performance, we modeled neural control of reaching with the human upper limb as a near-optimally feedback-controlled two-degree-of-freedom system with biologically based parameters. We added three sensorimotor impairments commonly associated with post-stroke hemiparesis - abnormal joint coupling, increased noise on internally modeled dynamics, and muscular weakness - and examined the impact on reaching performance...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813603/modeling-optical-spectra-of-large-organic-systems-using-real-time-propagation-of-semiempirical-effective-hamiltonians
#14
Soumen Ghosh, Amity Andersen, Laura Gagliardi, Christopher J Cramer, Niranjan Govind
We present an implementation of a time-dependent semiempirical method (INDO/S) in NWChem using real-time (RT) propagation to address, in principle, the entire spectrum of valence electronic excitations. Adopting this model, we study the UV-visible spectra of medium-sized systems like P3B2, f-coronene, and in addition much larger systems like ubiquitin in the gas phase and the betanin chromophore in the presence of two explicit solvents (water and methanol). RT-INDO/S provides qualitatively and indeed often quantitatively accurate results when compared with RT- TDDFT or experimental spectra...
August 16, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28813574/dynamic-imaging-of-the-eye-optic-nerve-and-extraocular-muscles-with-golden-angle-radial-mri
#15
Saikat Sengupta, David S Smith, Alex K Smith, E Brian Welch, Seth A Smith
Purpose: The eye and its accessory structures, the optic nerve and the extraocular muscles, form a complex dynamic system. In vivo magnetic resonance imaging (MRI) of this system in motion can have substantial benefits in understanding oculomotor functioning in health and disease, but has been restricted to date to imaging of static gazes only. The purpose of this work was to develop a technique to image the eye and its accessory visual structures in motion. Methods: Dynamic imaging of the eye was developed on a 3-Tesla MRI scanner, based on a golden angle radial sequence that allows freely selectable frame-rate and temporal-span image reconstructions from the same acquired data set...
August 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28813442/a-parallel-metaheuristic-for-large-mixed-integer-dynamic-optimization-problems-with-applications-in-computational-biology
#16
David R Penas, David Henriques, Patricia González, Ramón Doallo, Julio Saez-Rodriguez, Julio R Banga
BACKGROUND: We consider a general class of global optimization problems dealing with nonlinear dynamic models. Although this class is relevant to many areas of science and engineering, here we are interested in applying this framework to the reverse engineering problem in computational systems biology, which yields very large mixed-integer dynamic optimization (MIDO) problems. In particular, we consider the framework of logic-based ordinary differential equations (ODEs). METHODS: We present saCeSS2, a parallel method for the solution of this class of problems...
2017: PloS One
https://www.readbyqxmd.com/read/28813296/couple-conflict-insights-from-an-attachment-perspective
#17
REVIEW
Judith A Feeney, Gery C Karantzas
The experience of conflict is often cited as a highly stressful relational phenomenon by romantic couples, and can have negative implications for relationship satisfaction and for the longevity of romantic relationships. In this paper, we review extant research on couple conflict in romantic relationships from an attachment theory perspective. The research we review is underpinned by two central tenets: firstly, severe or persistent conflict activates the attachment system; secondly, responses to couple conflict involve complex attachment dynamics, shaped by partners' attachment anxiety and avoidance...
February 2017: Current Opinion in Psychology
https://www.readbyqxmd.com/read/28813143/effect-of-structure-and-disorder-on-the-charge-transport-in-defined-self-assembled-monolayers-of-organic-semiconductors
#18
Thomas Schmaltz, Bastian Gothe, Andreas Krause, Susanne Leitherer, Hans-Georg Steinrück, Michael Thoss, Timothy Clark, Marcus Halik
Self-assembled monolayer field-effect transistors (SAMFETs) are not only a promising new type of organic electronic device but also allow uniquely detailed analyses of structure-property correlations. The influence of the morphology on the charge transport is particularly pronounced, due to the confined monolayer of 2D-π-stacked organic semiconductor molecules. The morphology, in turn, is governed by relatively weak van-der-Waals interactions and is thus prone to dynamic structural fluctuations. Accordingly, combining electronic and physical characterization and time-averaged X-ray analyses with the dynamic information available at atomic resolution from simulations, allows us to characterize self-assembled monolayer (SAM-) based devices in unprecedented detail...
August 16, 2017: ACS Nano
https://www.readbyqxmd.com/read/28813018/biophysical-and-computational-studies-of-the-vcci-vmip-ii-complex
#19
Anna F Nguyen, Nai-Wei Kuo, Laura J Showalter, Ricardo Ramos, Cynthia M Dupureur, Michael E Colvin, Patricia J LiWang
Certain viruses have the ability to subvert the mammalian immune response, including interference in the chemokine system. Poxviruses produce the chemokine binding protein vCCI (viral CC chemokine inhibitor; also called 35K), which tightly binds to CC chemokines. To facilitate the study of vCCI, we first provide a protocol to produce folded vCCI from Escherichia coli (E. coli.) It is shown here that vCCI binds with unusually high affinity to viral Macrophage Inflammatory Protein-II (vMIP-II), a chemokine analog produced by the virus, human herpesvirus 8 (HHV-8)...
August 16, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28812895/correlating-free-volume-hole-distribution-to-the-glass-transition-temperature-of-epoxy-polymers
#20
Amin Aramoon, Timothy D Breitzman, Christopher F Woodward, Jaafar A El-Awady
A new algorithm is developed to quantify the free-volume hole distribution and its evolution in coarse-grained molecular dynamics simulations of polymeric networks. This is achieved by analyzing the geometry of the network rather than a voxelized image of the structure to accurately and efficiently find and quantify free-volume hole distributions within large scale simulations of polymer networks. The free-volume holes are quantified by fitting the largest ellipsoids and spheres in the free-volumes between polymer chains...
August 16, 2017: Journal of Physical Chemistry. B
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