The Experts below are selected from a list of 14634 Experts worldwide ranked by ideXlab platform
Sunil K. Agrawal - One of the best experts on this subject based on the ideXlab platform.
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human movement training with a cable driven arm exoskeleton Carex
IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2015Co-Authors: Ying Mao, Xin Jin, Geetanjali Gera Dutta, John P Scholz, Sunil K. AgrawalAbstract:In recent years, the authors have proposed lightweight exoskeleton designs for upper arm rehabilitation using multi-stage cable-driven parallel mechanism. Previously, the authors have demonstrated via experiments that it is possible to apply “assist-as-needed” forces in all directions at the end-effector with such an exoskeleton acting on an anthropomorphic machine arm. A human–exoskeleton interface was also presented to show the feasibility of Carex on human subjects. The goals of this paper are to 1) further address issues when Carex is mounted on human subjects, e.g., generation of continuous cable tension trajectories 2) demonstrate the feasibility and effectiveness of Carex on movement training of healthy human subjects and a stroke patient. In this research, Carex is rigidly attached to an arm orthosis worn by human subjects. The cable routing points are optimized to achieve a relatively large “tensioned” static workspace. A new cable tension planner based on quadratic programming is used to generate continuous cable tension trajectory for smooth motion. Experiments were carried out on eight healthy subjects. The experimental results show that Carex can help the subjects move closer to a prescribed circular path using the force fields generated by the exoskeleton. The subjects also adapt to the path shortly after training. Carex was also evaluated on a stroke patient to test the feasibility of its use on patients with neural impairment. The results show that the patient was able to move closer to a prescribed straight line path with the “assist-as-needed” force field.
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real time estimation of glenohumeral joint rotation center with cable driven arm exoskeleton Carex a cable based arm exoskeleton
Journal of Mechanisms and Robotics, 2014Co-Authors: Sunil K. AgrawalAbstract:In the past few years, the authors have proposed several prototypes of a Cable-driven upper ARm EXoskeleton (Carex) for arm rehabilitation. One of the assumptions of Carex was that the glenohumeral joint rotation center (GH-c) remains stationary in the inertial frame during motion, which leads to inaccuracy in the kinematic model and may hamper training performance. In this paper, we propose a novel approach to estimate GH-c using measurements of shoulder joint angles and cable lengths. This helps in locating the GH-c center appropriately within the kinematic model. As a result, more accurate kinematic model can be used to improve the training of human users. An estimation algorithm is presented to compute the GH-c in real-time. The algorithm was implemented on the latest prototype of Carex. Simulations and preliminary experimental results are presented to validate the proposed GH-c estimation method.
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transition from mechanical arm to human arm with Carex a cable driven arm exoskeleton Carex for neural rehabilitation
International Conference on Robotics and Automation, 2012Co-Authors: Sunil K. AgrawalAbstract:Rehabilitation robotic devices have been actively explored for training patients with impaired neural functions or assisting those with weak limbs due to aging or diseases. In recent years, the authors have proposed light-weight exoskeleton designs for the upper arm, in which rigid links of the exoskeleton are replaced by lightweight cuffs attached to the moving limb segments of the human arm. Cables, driven by motors, are routed through these cuffs to move the limb segments. However, a scientific limitation of a cable driven system is that cables can only pull but not push. Previously, the authors have demonstrated by experiments with Carex mounted on a robotic arm that it is possible to achieve forces in all directions at the wrist. The goal of this paper is to demonstrate via experiments that Carex is able to apply similar forces at the end-effector with healthy subjects in the device. In this research, Carex was rigidly attached to an arm orthosis which can be tightly strapped on the human arm. The cable routing points were optimized for large “tensioned” workspace of the arm for typical Activities of Daily Living (ADLs). An orientation sensor was used to measure shoulder joint angles. Experiments are presented to validate the new sensor implementation and show the performance of Carex on healthy subjects.
Sunil Kumar Agrawal - One of the best experts on this subject based on the ideXlab platform.
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Design of a 7-DOF Cable-Driven Arm Exoskeleton (Carex-7) and a Controller for Dexterous Motion Training or Assistance
IEEE ASME Transactions on Mechatronics, 2017Co-Authors: Xiang Cui, Weihai Chen, Xin Jin, Sunil Kumar AgrawalAbstract:Abstract: The training for both translation and rotation of the hand is desirable for patients with impairments. This paper focuses on the design and control of a 7-degree-of-freedom cable-driven arm exoskeleton (Carex-7), used for dexterous motion (including translation and rotation) training or assistance of the whole-arm. The Carex-7 includes an additional wrist module compared with Carex, and eight cables are routed through the exoskeleton cuffs to drive the whole-arm motion. Based on the “assist-as-needed” paradigm, a novel wrench-field controller was designed to regulate a needed wrench (force and torque) on the hand for assisting its dexterous manipulation. Healthy subjects participated in path-tracking experiments while wearing Carex-7. The experimental results show that the Carex-7 with the new wrench-field controller can help the subjects to follow the path more closely, and this demonstrates the effectiveness of the device. The current design of Carex-7 is unique and offers significant improvements and new functionality over the existing Carex. The novel features are the following: 1) Carex-7 is an exoskeleton for the full human arm, including shoulder, elbow, and the wrist, with new design issues; and 2) controller of Carex-7 builds on a screw-theoretic approach and assists both translation and rotation of the hand, allowing for dexterous hand reorientation, which is required in everyday tasks.
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Design of a cable-driven arm exoskeleton (Carex) for neural rehabilitation
IEEE Transactions on Robotics, 2012Co-Authors: Ying Mao, Sunil Kumar AgrawalAbstract:Abstract—Rehabilitation robots are, currently, being explored for training of neural impaired subjects or for assistance of those with weak limbs. Intensive training of neurally impaired subjects, with quantifiable outcomes, is the eventual goal of these robot ex- oskeletons. Conventional arm exoskeletons for rehabilitation are bulky and heavy. In recent years, the authors have proposed to make lightweight exoskeletons for rehabilitation by replacing the rigid links of the exoskeletonwith lightweight cuffsfixedto themov- ing limb segments of the human arm. Cables are routed through these cuffs, which are driven by motors, to move the limb seg- ments relative to each other. However, a scientific limitation of a cable-driven system is that each cable can only pull but not push. This paper is the first to demonstrate via experiments with cable- driven arm exoskeleton (Carex) that it is possible to achieve desired forces on the hand, i.e., both pull and push, in any direction as re- quired in neural training. In this research, an anthropomorphic arm was used to bench test the design and control concepts pro- posed inCarex.As described in this paper,Carexwas attached to the limb segments of a five degree-of-freedom anthropomorphic arm instrumented with joint sensors. The cuffs of Carex were designed to have adjustable cable routing points to optimize the “tensioned” workspace of the anthropomorphic arm. Simulation results of force field for training and rehabilitation of the arm are first presented. Experiments are conducted to show the perfor- mance of a Carex force field controller when human subjects pull the end-effector of the anthropomorphic arm to travel on pre- scribed paths. The human–exoskeleton interface is also presented at the end of this paper to demonstrate the feasibility of Carex on human arm.
Bruce A Ford - One of the best experts on this subject based on the ideXlab platform.
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why are there so many sedges sumatroscirpeae a missing piece in the evolutionary puzzle of the giant genus Carex cyperaceae
Molecular Phylogenetics and Evolution, 2018Co-Authors: Etienne Leveillebourret, Julian R Starr, Bruce A FordAbstract:For over a century, the origins and mechanisms underlying the diversification of the enormous temperate genus Carex (>2100 species; Cariceae, Cyperaceae) have remained largely speculative. Characteristics such as its diverse ecology, varied biogeography, and intriguing cytology have made Carex a powerful model for studying plant evolution, but its uncertain sister-group relationships hinder its use in studies that depend on accurate ancestral state estimates and biogeographic inferences. To identify the sister to Carex, we estimated the phylogeny of all genera in the Cariceae-Dulichieae-Scirpeae clade (CDS) using three plastid and two nuclear ribosomal markers. Ancestral state reconstructions of key characters were made, and a time-calibrated tree estimated. Carex is strongly supported as sister to the rare East Asian Sumatroscirpus, sole genus of a new tribe, Sumatroscirpeae trib. nov. Believed to be unique to Carex, the perigynium (prophyllar bract enclosing a flower) is in fact a synapomorphy shared with this small tribe (∼4 species) that appeared 36 Mya. We thus suggest the initial key innovation in the remarkable diversification of Carex is not the perigynium, but could be the release of mechanical constraints on perigynia through spikelet truncation, resulting in novel adaptive morphologies. Monoecy, chromosomal change, and rapid inflorescence development enabling phenological isolation may also be involved. The tiny tribe Sumatroscirpeae will provide unprecedented insights into the inflorescence homology, evolution, diversification, and biogeographic history of its sister-group Carex, one of the world's most diverse plant lineages.
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megaphylogenetic specimen level approaches to the Carex cyperaceae phylogeny using its ets and matk sequences implications for classification
Systematic Botany, 2016Co-Authors: Pedro Jimenezmejias, Julian R Starr, Bruce A Ford, Marcial Escudero, Marlene Hahn, Kate Lueders, Bethany H Brown, Brianna N Chouinard, Kyong Sook Chung, K A FordAbstract:Abstract We present the first large-scale phylogenetic hypothesis for the genus Carex based on 996 of the 1983 accepted species (50.23%). We used a supermatrix approach using three DNA regions: ETS, ITS and matK. Every concatenated sequence was derived from a single specimen. The topology of our phylogenetic reconstruction largely agreed with previous studies. We also gained new insights into the early divergence structure of the two largest clades, core Carex and Vignea clades, challenging some previous evolutionary hypotheses about inflorescence structure. Most sections were recovered as non-monophyletic. Homoplasy of characters traditionally selected as relevant for classification, historical misunderstanding of how morphology varies across Carex, and regional rather than global views of Carex diversity seem to be the main reasons for the high levels of polyphyly and paraphyly in the current infrageneric classification.
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three new early diverging Carex cariceae cyperaceae lineages from east and southeast asia with important evolutionary and biogeographic implications
Molecular Phylogenetics and Evolution, 2015Co-Authors: Julian R Starr, Francesco H Janzen, Bruce A FordAbstract:Traditional Cariceae and Carex (1966 spp.) classifications recognised five genera (Carex, Cymophyllus, Kobresia, Schoenoxiphium, Uncinia) and four subgenera (Carex, Vignea, Vigneastra, Psyllophora). However, molecular studies have shown that only Carex, divided into five major lineages (the Core Carex, Schoenoxiphium, Core Unispicate, Vignea and Siderostictae Clades), is natural. These studies have also suggested that many early diverging tribal lineages are East Asian in origin, but the sampling of East Asian groups has been poor, and support for relationships within and among major Cariceae clades has been weak. To test deep patterns of relationship in Carex we assembled the longest sequence dataset yet (ITS, ETS 1f, matK, ndhF, rps16; ca. 4400bp) with taxonomic sampling focused on critical East and Southeast Asian Carex sections that have blurred subgeneric limits (Decorae, Graciles, Mundae) or have been at the heart of theories on tribal origins (Hemiscaposae, Indicae, Surculosae, Euprepes, Mapaniifoliae, Hypolytroides). Results indicate that subg. Vigneastra is highly polyphyletic (in five of seven major lineages recognised), and they provide the strongest support yet seen for all previously recognised major Cariceae clades in a single analysis (⩾93% BS). Moreover, results provide strong evidence for three previously unrecognised early diverging East and Southeast Asian lineages: a "Hypolytroides Clade" (sect. Hypolytroides) sister to the Siderostictae Clade, and for a "Dissitiflora Lineage" (sect. Mundae) and a morphologically diverse "Small Core Carex Clade" (sects. Graciles, Decorae, Mapaniifoliae, Euprepes, Indicae) as successive sisters to approximately 1400 species in the Core Carex Clade. Our findings also suggest that morphological diversification may have occurred in clades dominated by Asian species followed by canalization to a narrower range of morphologies in species-rich, cosmopolitan lineages.
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phylogeny and evolution in cariceae cyperaceae current knowledge and future directions
Botanical Review, 2009Co-Authors: Julian R Starr, Bruce A FordAbstract:The goal of this study was to review the impact of DNA sequence analyses on our understanding of Cariceae phylogeny, classification and evolution. To explore character evolution, 105 taxa from four different studies were included in an nrDNA ITS + ETS 1f analysis of all recognized genera (Carex, Cymophyllus, Kobresia, Schoenoxiphium, Uncinia) and Carex subgenera (Carex, Psyllophora, Vignea, Vigneastra). As in previous analyses, four major Cariceae clades were recovered: (1) a “Core Carex Clade” (subg. Carex, Vigneastra, Psyllophora p.p); (2) A “Vignea Clade” (subg. Vignea, Psyllophora p.p.); (3) a “Schoenoxiphium Clade” (Schoenoxiphium, subg. Psyllophora p.p.), and (4) a “Core Unispicate Clade” (Uncinia, Kobresia, subg. Psyllophora p.p.). All studies provide strong support (86–100% BS) for the Core Carex and Vignea Clades, but only weak to moderate support (<50%–78% BS) for the Core Unispicate and Schoenoxiphium Clades. The relationships of these groups are unresolved. Studies suggest that Carex is either paraphyletic with respect to all Cariceae genera or to all genera except Schoenoxiphium. Kobresia is a grade, but Uncinia and possibly Schoenoxiphium are monophyletic. The monotypic Cymophyllus is indistinct from Carex subg. Psyllophora species. Character analyses indicate that inflorescence proliferation and reduction have occurred in all major clades, and that the Cariceae’s unisexual flowers have evolved from perfect flowers. The ancestor to Cariceae possessed a multispicate inflorescence with cladoprophylls and female spikelets with tristigmatic gynoecia and closed utricles. This morphology is most similar to extant Carex subg. Carex species, which contradicts the nearly unanimous assumption that the highly compound inflorescences of Schoenoxiphium are primitive. Since taxonomic sampling and statistical support for phylogenies have generally been poor, we advocate the temporary maintenance of the four traditional Carex subgenera with androgynous unispicate species placed within subg. Psyllophora and dioecious and gynaecandrous unispicate species distributed amongst subgenera Carex and Vignea. A collective effort focused on developing new nuclear markers, on increasing taxonomic and geographic sampling, and on studying development within the context of phylogeny, is needed to develop a phylogenetic classification of Cariceae.
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the phylogenetic position of Carex section phyllostachys and its implications for phylogeny and subgeneric circumscription in Carex cyperaceae
American Journal of Botany, 1999Co-Authors: Julian R Starr, Randall J Bayer, Bruce A FordAbstract:Wide speculation surrounds the origin and phylogenetic relationships of the most highly reduced sections in the genus Carex. In order to gain a better understanding of phylogeny in Carex, the relationship of the reduced sect. Phyllostachys to 12 putatively related sections, representing all four subgenera (PrimoCarex, IndoCarex, Carex, Vignea), was inferred from sequences of the ITS (internal transcribed spacer) region of nrDNA. Phylogenetic reconstructions identified two main clades: (1) a "compound" clade composed of sections from subg. IndoCarex, PrimoCarex, and a portion of subg. Carex, and (2) a "reduced" clade consisting of sections from subg. Carex (Phyllostachys) and PrimoCarex (Filifoliae and Firmiculmes). Subgenus IndoCarex was paraphyletic within the "compound" clade supporting classifications that have merged it within a wider subg. IndoCarex/Carex/PrimoCarex line. Subgenus PrimoCarex was polyphyletic. This result was consistent with theories that extreme reduction has occurred along several different evolutionary lines in Carex. Phylogenetic theories inferred from the presence or abnormal growth of the rachilla were not supported by tree topologies. Difficult sectional circumscriptions, such as the separation of sections Laxiflorae and Careyanae, were strongly upheld by sequence data. The ITS region is an effective tool for defining sectional limits and for estimating relationships among sections in Carex, but does not provide enough phylogenetic information to fully resolve relationships below the sectional level.
Julian R Starr - One of the best experts on this subject based on the ideXlab platform.
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why are there so many sedges sumatroscirpeae a missing piece in the evolutionary puzzle of the giant genus Carex cyperaceae
Molecular Phylogenetics and Evolution, 2018Co-Authors: Etienne Leveillebourret, Julian R Starr, Bruce A FordAbstract:For over a century, the origins and mechanisms underlying the diversification of the enormous temperate genus Carex (>2100 species; Cariceae, Cyperaceae) have remained largely speculative. Characteristics such as its diverse ecology, varied biogeography, and intriguing cytology have made Carex a powerful model for studying plant evolution, but its uncertain sister-group relationships hinder its use in studies that depend on accurate ancestral state estimates and biogeographic inferences. To identify the sister to Carex, we estimated the phylogeny of all genera in the Cariceae-Dulichieae-Scirpeae clade (CDS) using three plastid and two nuclear ribosomal markers. Ancestral state reconstructions of key characters were made, and a time-calibrated tree estimated. Carex is strongly supported as sister to the rare East Asian Sumatroscirpus, sole genus of a new tribe, Sumatroscirpeae trib. nov. Believed to be unique to Carex, the perigynium (prophyllar bract enclosing a flower) is in fact a synapomorphy shared with this small tribe (∼4 species) that appeared 36 Mya. We thus suggest the initial key innovation in the remarkable diversification of Carex is not the perigynium, but could be the release of mechanical constraints on perigynia through spikelet truncation, resulting in novel adaptive morphologies. Monoecy, chromosomal change, and rapid inflorescence development enabling phenological isolation may also be involved. The tiny tribe Sumatroscirpeae will provide unprecedented insights into the inflorescence homology, evolution, diversification, and biogeographic history of its sister-group Carex, one of the world's most diverse plant lineages.
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megaphylogenetic specimen level approaches to the Carex cyperaceae phylogeny using its ets and matk sequences implications for classification
Systematic Botany, 2016Co-Authors: Pedro Jimenezmejias, Julian R Starr, Bruce A Ford, Marcial Escudero, Marlene Hahn, Kate Lueders, Bethany H Brown, Brianna N Chouinard, Kyong Sook Chung, K A FordAbstract:Abstract We present the first large-scale phylogenetic hypothesis for the genus Carex based on 996 of the 1983 accepted species (50.23%). We used a supermatrix approach using three DNA regions: ETS, ITS and matK. Every concatenated sequence was derived from a single specimen. The topology of our phylogenetic reconstruction largely agreed with previous studies. We also gained new insights into the early divergence structure of the two largest clades, core Carex and Vignea clades, challenging some previous evolutionary hypotheses about inflorescence structure. Most sections were recovered as non-monophyletic. Homoplasy of characters traditionally selected as relevant for classification, historical misunderstanding of how morphology varies across Carex, and regional rather than global views of Carex diversity seem to be the main reasons for the high levels of polyphyly and paraphyly in the current infrageneric classification.
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three new early diverging Carex cariceae cyperaceae lineages from east and southeast asia with important evolutionary and biogeographic implications
Molecular Phylogenetics and Evolution, 2015Co-Authors: Julian R Starr, Francesco H Janzen, Bruce A FordAbstract:Traditional Cariceae and Carex (1966 spp.) classifications recognised five genera (Carex, Cymophyllus, Kobresia, Schoenoxiphium, Uncinia) and four subgenera (Carex, Vignea, Vigneastra, Psyllophora). However, molecular studies have shown that only Carex, divided into five major lineages (the Core Carex, Schoenoxiphium, Core Unispicate, Vignea and Siderostictae Clades), is natural. These studies have also suggested that many early diverging tribal lineages are East Asian in origin, but the sampling of East Asian groups has been poor, and support for relationships within and among major Cariceae clades has been weak. To test deep patterns of relationship in Carex we assembled the longest sequence dataset yet (ITS, ETS 1f, matK, ndhF, rps16; ca. 4400bp) with taxonomic sampling focused on critical East and Southeast Asian Carex sections that have blurred subgeneric limits (Decorae, Graciles, Mundae) or have been at the heart of theories on tribal origins (Hemiscaposae, Indicae, Surculosae, Euprepes, Mapaniifoliae, Hypolytroides). Results indicate that subg. Vigneastra is highly polyphyletic (in five of seven major lineages recognised), and they provide the strongest support yet seen for all previously recognised major Cariceae clades in a single analysis (⩾93% BS). Moreover, results provide strong evidence for three previously unrecognised early diverging East and Southeast Asian lineages: a "Hypolytroides Clade" (sect. Hypolytroides) sister to the Siderostictae Clade, and for a "Dissitiflora Lineage" (sect. Mundae) and a morphologically diverse "Small Core Carex Clade" (sects. Graciles, Decorae, Mapaniifoliae, Euprepes, Indicae) as successive sisters to approximately 1400 species in the Core Carex Clade. Our findings also suggest that morphological diversification may have occurred in clades dominated by Asian species followed by canalization to a narrower range of morphologies in species-rich, cosmopolitan lineages.
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phylogeny and evolution in cariceae cyperaceae current knowledge and future directions
Botanical Review, 2009Co-Authors: Julian R Starr, Bruce A FordAbstract:The goal of this study was to review the impact of DNA sequence analyses on our understanding of Cariceae phylogeny, classification and evolution. To explore character evolution, 105 taxa from four different studies were included in an nrDNA ITS + ETS 1f analysis of all recognized genera (Carex, Cymophyllus, Kobresia, Schoenoxiphium, Uncinia) and Carex subgenera (Carex, Psyllophora, Vignea, Vigneastra). As in previous analyses, four major Cariceae clades were recovered: (1) a “Core Carex Clade” (subg. Carex, Vigneastra, Psyllophora p.p); (2) A “Vignea Clade” (subg. Vignea, Psyllophora p.p.); (3) a “Schoenoxiphium Clade” (Schoenoxiphium, subg. Psyllophora p.p.), and (4) a “Core Unispicate Clade” (Uncinia, Kobresia, subg. Psyllophora p.p.). All studies provide strong support (86–100% BS) for the Core Carex and Vignea Clades, but only weak to moderate support (<50%–78% BS) for the Core Unispicate and Schoenoxiphium Clades. The relationships of these groups are unresolved. Studies suggest that Carex is either paraphyletic with respect to all Cariceae genera or to all genera except Schoenoxiphium. Kobresia is a grade, but Uncinia and possibly Schoenoxiphium are monophyletic. The monotypic Cymophyllus is indistinct from Carex subg. Psyllophora species. Character analyses indicate that inflorescence proliferation and reduction have occurred in all major clades, and that the Cariceae’s unisexual flowers have evolved from perfect flowers. The ancestor to Cariceae possessed a multispicate inflorescence with cladoprophylls and female spikelets with tristigmatic gynoecia and closed utricles. This morphology is most similar to extant Carex subg. Carex species, which contradicts the nearly unanimous assumption that the highly compound inflorescences of Schoenoxiphium are primitive. Since taxonomic sampling and statistical support for phylogenies have generally been poor, we advocate the temporary maintenance of the four traditional Carex subgenera with androgynous unispicate species placed within subg. Psyllophora and dioecious and gynaecandrous unispicate species distributed amongst subgenera Carex and Vignea. A collective effort focused on developing new nuclear markers, on increasing taxonomic and geographic sampling, and on studying development within the context of phylogeny, is needed to develop a phylogenetic classification of Cariceae.
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phylogenetic relationships in tribe cariceae cyperaceae based on nested analyses of four molecular data sets
Aliso, 2007Co-Authors: Marcia J Waterway, Julian R StarrAbstract:Phylogenelic reconstruction for Carex and relatives in tribe Cariceae is complicated by species richness and nearly cosmopolitan distribution. In this investigation, our main objective was to estimate evolutionary relationships in tribe Cariceae using DNA sequence data from two spacer regions in nuclear ribosomal genes (ITS and ETS-lf) combined with noncoding chloroplast DNA (trnL intron, tnrL-trnF intergenic spacer, and trnE-trnD intergenic spacers). Parsimony analyses of separate and combined data and Bayesian analysis of the combined data matrix revealed strong support for monophyly of tribe Cariceae and for monophyly of two major lineages, one comprising principally Carex subgen. Carex and Vigneastra, and the other representing subgen. Vignea. A third clade with representatives from Kabresia and Uncinia, along with Cymophyllus fraserianus, Carex curvula, and several unispicate Carex received weak-to-moderate support. A small clade comprising Schoenoxiphium and two unispicate carices was placed as sister to the clades comprising multispicate Carex species in the parsimony analysis, but sister to the clade of Kobresia, Uncinia, and unispicate Carex in the Bayesian analysis. Two large widespread groups within suhgen. Carex, sect. Hymenochlaenae and sect. Physocarpae S.I. ("bladder sedges"), were highly polyphyletic, while ten clades that grouped species from two or more sections were each strongly supported as monophyletic. Within suhgen. Vignea, three sections were strongly supported as monophyletic while sects. Phaestoglochin and Vulpinae were polyphyletic. Adding the variable ETS-1f region improved resolution and bootstrap support values over previous studies, but many of the characters supporting major branches came from the trnL region.
Ying Mao - One of the best experts on this subject based on the ideXlab platform.
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human movement training with a cable driven arm exoskeleton Carex
IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2015Co-Authors: Ying Mao, Xin Jin, Geetanjali Gera Dutta, John P Scholz, Sunil K. AgrawalAbstract:In recent years, the authors have proposed lightweight exoskeleton designs for upper arm rehabilitation using multi-stage cable-driven parallel mechanism. Previously, the authors have demonstrated via experiments that it is possible to apply “assist-as-needed” forces in all directions at the end-effector with such an exoskeleton acting on an anthropomorphic machine arm. A human–exoskeleton interface was also presented to show the feasibility of Carex on human subjects. The goals of this paper are to 1) further address issues when Carex is mounted on human subjects, e.g., generation of continuous cable tension trajectories 2) demonstrate the feasibility and effectiveness of Carex on movement training of healthy human subjects and a stroke patient. In this research, Carex is rigidly attached to an arm orthosis worn by human subjects. The cable routing points are optimized to achieve a relatively large “tensioned” static workspace. A new cable tension planner based on quadratic programming is used to generate continuous cable tension trajectory for smooth motion. Experiments were carried out on eight healthy subjects. The experimental results show that Carex can help the subjects move closer to a prescribed circular path using the force fields generated by the exoskeleton. The subjects also adapt to the path shortly after training. Carex was also evaluated on a stroke patient to test the feasibility of its use on patients with neural impairment. The results show that the patient was able to move closer to a prescribed straight line path with the “assist-as-needed” force field.
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Design of a cable-driven arm exoskeleton (Carex) for neural rehabilitation
IEEE Transactions on Robotics, 2012Co-Authors: Ying Mao, Sunil Kumar AgrawalAbstract:Abstract—Rehabilitation robots are, currently, being explored for training of neural impaired subjects or for assistance of those with weak limbs. Intensive training of neurally impaired subjects, with quantifiable outcomes, is the eventual goal of these robot ex- oskeletons. Conventional arm exoskeletons for rehabilitation are bulky and heavy. In recent years, the authors have proposed to make lightweight exoskeletons for rehabilitation by replacing the rigid links of the exoskeletonwith lightweight cuffsfixedto themov- ing limb segments of the human arm. Cables are routed through these cuffs, which are driven by motors, to move the limb seg- ments relative to each other. However, a scientific limitation of a cable-driven system is that each cable can only pull but not push. This paper is the first to demonstrate via experiments with cable- driven arm exoskeleton (Carex) that it is possible to achieve desired forces on the hand, i.e., both pull and push, in any direction as re- quired in neural training. In this research, an anthropomorphic arm was used to bench test the design and control concepts pro- posed inCarex.As described in this paper,Carexwas attached to the limb segments of a five degree-of-freedom anthropomorphic arm instrumented with joint sensors. The cuffs of Carex were designed to have adjustable cable routing points to optimize the “tensioned” workspace of the anthropomorphic arm. Simulation results of force field for training and rehabilitation of the arm are first presented. Experiments are conducted to show the perfor- mance of a Carex force field controller when human subjects pull the end-effector of the anthropomorphic arm to travel on pre- scribed paths. The human–exoskeleton interface is also presented at the end of this paper to demonstrate the feasibility of Carex on human arm.
