The Experts below are selected from a list of 8136 Experts worldwide ranked by ideXlab platform
Yueqian Liang - One of the best experts on this subject based on the ideXlab platform.
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tangent vector field approach for Curved Path following with input saturation
Systems & Control Letters, 2017Co-Authors: Yueqian Liang, Yingmin JiaAbstract:Abstract Path following is an indispensable function for autonomous vehicles. Desired Paths may be of arbitrary shape, not just the mostly investigated straight lines and circles. This paper addresses the Path following problem of arbitrary twice differentiable curves using vector-field-based approach. A tangent vector field is constructed through coordinate transformation, and a sufficient condition for its feasibility concerning the input saturation is given out. A saturated turning velocity controller is designed and its Lyapunov stability is discussed in detail. Numerical simulation results show us that the Path following performance of the proposed approach is comparable with that of the literature while involving 5 less parameters to be set.
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Combined Vector Field Approach for 2D and 3D Arbitrary Twice Differentiable Curved Path Following with Constrained UAVs
Journal of Intelligent & Robotic Systems, 2015Co-Authors: Yueqian Liang, Yingmin JiaAbstract:Path following is an essential requirement for unmanned aerial vehicles (UAVs). Path following problems of 2-dimensional (2D) straight lines and planar circles have been studied and many approaches have been proposed during the past few years. In this paper the problem of following arbitrary twice differentiable Curved Paths in both 2D and 3D spaces is investigated. Based on the Helmholtz theorem, respective combined guidance vector fields for any given 2D and 3D arbitrary twice differentiable Curved Paths are constructed by trading off the respective conservative and solenoidal vector fields making use of the defined distance between the UAV and the desired Path. Conditions for the two combined vector fields to be globally feasible are given. UAV input constraints and constant wind disturbance are assumed to be present. By tracking the constructed combined vector fields, a saturated course rate controller for 2D Curved Path following and a jointly saturated course rate and climb rate controller for 3D Curved Path following are designed. The Lyapunov stability of the saturated course rate controller for 2D Curved Path following is proved. Numerical simulations are given to assess the proposed approach.
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combined vector field approach for planar Curved Path following with fixed wing uavs
Advances in Computing and Communications, 2015Co-Authors: Yueqian Liang, Yingmin Jia, Zhuo Wang, Fumitoshi MatsunoAbstract:In this paper the problem of planar Curved Path following using fixed-wing unmanned aerial vehicles (UAVs) is studied. UAV input constraints and constant wind disturbance are considered. A combined vector field is proposed by trading off a conservative vector field and a solenoidal vector field. Accordingly a saturated course rate controller is designed, and its stability is discussed through the Lyapunov stability theory. Simulation examples show us the effectiveness of the approach.
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vector field guidance for three dimensional Curved Path following with fixed wing uavs
Advances in Computing and Communications, 2015Co-Authors: Yueqian Liang, Yingmin Jia, Jun ZhangAbstract:This paper investigates the three-dimensional (3D) Curved Path following problem using fixed-wing unmanned aerial vehicles (UAVs) in the presence of constant wind disturbance. Vector field based approaches are used as the solution. Two vector fields are first developed, one is the tangent vector field based on Path tangent vector and coordinate transformation, and the other is the combined vector field based on the combination of a conservative vector field and a solenoidal vector field. A unified jointly saturated course rate and saturated climb rate controller is designed based on the proposed vector fields. Simulations are conducted to demonstrate the effectiveness of the proposed approach.
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ACC - Combined vector field approach for planar Curved Path following with fixed-wing UAVs
2015 American Control Conference (ACC), 2015Co-Authors: Yueqian Liang, Yingmin Jia, Zhuo Wang, Fumitoshi MatsunoAbstract:In this paper the problem of planar Curved Path following using fixed-wing unmanned aerial vehicles (UAVs) is studied. UAV input constraints and constant wind disturbance are considered. A combined vector field is proposed by trading off a conservative vector field and a solenoidal vector field. Accordingly a saturated course rate controller is designed, and its stability is discussed through the Lyapunov stability theory. Simulation examples show us the effectiveness of the approach.
Yingmin Jia - One of the best experts on this subject based on the ideXlab platform.
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tangent vector field approach for Curved Path following with input saturation
Systems & Control Letters, 2017Co-Authors: Yueqian Liang, Yingmin JiaAbstract:Abstract Path following is an indispensable function for autonomous vehicles. Desired Paths may be of arbitrary shape, not just the mostly investigated straight lines and circles. This paper addresses the Path following problem of arbitrary twice differentiable curves using vector-field-based approach. A tangent vector field is constructed through coordinate transformation, and a sufficient condition for its feasibility concerning the input saturation is given out. A saturated turning velocity controller is designed and its Lyapunov stability is discussed in detail. Numerical simulation results show us that the Path following performance of the proposed approach is comparable with that of the literature while involving 5 less parameters to be set.
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Combined Vector Field Approach for 2D and 3D Arbitrary Twice Differentiable Curved Path Following with Constrained UAVs
Journal of Intelligent & Robotic Systems, 2015Co-Authors: Yueqian Liang, Yingmin JiaAbstract:Path following is an essential requirement for unmanned aerial vehicles (UAVs). Path following problems of 2-dimensional (2D) straight lines and planar circles have been studied and many approaches have been proposed during the past few years. In this paper the problem of following arbitrary twice differentiable Curved Paths in both 2D and 3D spaces is investigated. Based on the Helmholtz theorem, respective combined guidance vector fields for any given 2D and 3D arbitrary twice differentiable Curved Paths are constructed by trading off the respective conservative and solenoidal vector fields making use of the defined distance between the UAV and the desired Path. Conditions for the two combined vector fields to be globally feasible are given. UAV input constraints and constant wind disturbance are assumed to be present. By tracking the constructed combined vector fields, a saturated course rate controller for 2D Curved Path following and a jointly saturated course rate and climb rate controller for 3D Curved Path following are designed. The Lyapunov stability of the saturated course rate controller for 2D Curved Path following is proved. Numerical simulations are given to assess the proposed approach.
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combined vector field approach for planar Curved Path following with fixed wing uavs
Advances in Computing and Communications, 2015Co-Authors: Yueqian Liang, Yingmin Jia, Zhuo Wang, Fumitoshi MatsunoAbstract:In this paper the problem of planar Curved Path following using fixed-wing unmanned aerial vehicles (UAVs) is studied. UAV input constraints and constant wind disturbance are considered. A combined vector field is proposed by trading off a conservative vector field and a solenoidal vector field. Accordingly a saturated course rate controller is designed, and its stability is discussed through the Lyapunov stability theory. Simulation examples show us the effectiveness of the approach.
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vector field guidance for three dimensional Curved Path following with fixed wing uavs
Advances in Computing and Communications, 2015Co-Authors: Yueqian Liang, Yingmin Jia, Jun ZhangAbstract:This paper investigates the three-dimensional (3D) Curved Path following problem using fixed-wing unmanned aerial vehicles (UAVs) in the presence of constant wind disturbance. Vector field based approaches are used as the solution. Two vector fields are first developed, one is the tangent vector field based on Path tangent vector and coordinate transformation, and the other is the combined vector field based on the combination of a conservative vector field and a solenoidal vector field. A unified jointly saturated course rate and saturated climb rate controller is designed based on the proposed vector fields. Simulations are conducted to demonstrate the effectiveness of the proposed approach.
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ACC - Combined vector field approach for planar Curved Path following with fixed-wing UAVs
2015 American Control Conference (ACC), 2015Co-Authors: Yueqian Liang, Yingmin Jia, Zhuo Wang, Fumitoshi MatsunoAbstract:In this paper the problem of planar Curved Path following using fixed-wing unmanned aerial vehicles (UAVs) is studied. UAV input constraints and constant wind disturbance are considered. A combined vector field is proposed by trading off a conservative vector field and a solenoidal vector field. Accordingly a saturated course rate controller is designed, and its stability is discussed through the Lyapunov stability theory. Simulation examples show us the effectiveness of the approach.
Jun Zhang - One of the best experts on this subject based on the ideXlab platform.
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vector field guidance for three dimensional Curved Path following with fixed wing uavs
Advances in Computing and Communications, 2015Co-Authors: Yueqian Liang, Yingmin Jia, Jun ZhangAbstract:This paper investigates the three-dimensional (3D) Curved Path following problem using fixed-wing unmanned aerial vehicles (UAVs) in the presence of constant wind disturbance. Vector field based approaches are used as the solution. Two vector fields are first developed, one is the tangent vector field based on Path tangent vector and coordinate transformation, and the other is the combined vector field based on the combination of a conservative vector field and a solenoidal vector field. A unified jointly saturated course rate and saturated climb rate controller is designed based on the proposed vector fields. Simulations are conducted to demonstrate the effectiveness of the proposed approach.
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ACC - Vector field guidance for three-dimensional Curved Path following with fixed-wing UAVs
2015 American Control Conference (ACC), 2015Co-Authors: Yueqian Liang, Yingmin Jia, Jun ZhangAbstract:This paper investigates the three-dimensional (3D) Curved Path following problem using fixed-wing unmanned aerial vehicles (UAVs) in the presence of constant wind disturbance. Vector field based approaches are used as the solution. Two vector fields are first developed, one is the tangent vector field based on Path tangent vector and coordinate transformation, and the other is the combined vector field based on the combination of a conservative vector field and a solenoidal vector field. A unified jointly saturated course rate and saturated climb rate controller is designed based on the proposed vector fields. Simulations are conducted to demonstrate the effectiveness of the proposed approach.
Fumitoshi Matsuno - One of the best experts on this subject based on the ideXlab platform.
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combined vector field approach for planar Curved Path following with fixed wing uavs
Advances in Computing and Communications, 2015Co-Authors: Yueqian Liang, Yingmin Jia, Zhuo Wang, Fumitoshi MatsunoAbstract:In this paper the problem of planar Curved Path following using fixed-wing unmanned aerial vehicles (UAVs) is studied. UAV input constraints and constant wind disturbance are considered. A combined vector field is proposed by trading off a conservative vector field and a solenoidal vector field. Accordingly a saturated course rate controller is designed, and its stability is discussed through the Lyapunov stability theory. Simulation examples show us the effectiveness of the approach.
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ACC - Combined vector field approach for planar Curved Path following with fixed-wing UAVs
2015 American Control Conference (ACC), 2015Co-Authors: Yueqian Liang, Yingmin Jia, Zhuo Wang, Fumitoshi MatsunoAbstract:In this paper the problem of planar Curved Path following using fixed-wing unmanned aerial vehicles (UAVs) is studied. UAV input constraints and constant wind disturbance are considered. A combined vector field is proposed by trading off a conservative vector field and a solenoidal vector field. Accordingly a saturated course rate controller is designed, and its stability is discussed through the Lyapunov stability theory. Simulation examples show us the effectiveness of the approach.
Jessie M. Vanswearingen - One of the best experts on this subject based on the ideXlab platform.
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Spatiotemporal variability underlying skill in Curved-Path walking.
Gait & posture, 2018Co-Authors: Kaylynn Bland, Kristin A. Lowry, Alex C. Krajek, Taylor Woods, Jessie M. VanswearingenAbstract:Abstract Background Daily life walking frequently involves Curved Paths. While mean gait characteristics and orientation of the body during Curved Path walking have been described, little has been reported about spatiotemporal variability during Curved Path walking and its relation to the motor skill of walking in older adults. Research question Among community-dwelling older adults, is greater spatiotemporal variability during Curved Path walking related to better Curved Path walking ability? Methods Community dwelling older adults (n = 34) completed the Figure-of-8 Walk Test (F8W, a measure of Curved Path walking ability) and usual straight Path walking on an instrumented walkway. Standard deviations for step length, stride width and step time (step length variability, SLV, stride width variability, SWV, step time variability, STV) during both conditions were determined, along with time and number of steps to complete F8W. Associations were examined with Pearson r correlation coefficients, regressions determined contributions of variability during Curved Path walking to F8W performance, and AUC analyses were used to determine the ability of variability during Curved Path walking to distinguish better vs poorer F8W performance. Results F8W time and steps were negatively associated with both SLV (r’s = −0.37, p Significance Greater spatial variability, particularly SWV, was associated with better motor skill of Curved Path walking. It is important for clinicians to understand the variables that contribute to successful performance of complex walking tasks as these can be targets for rehabilitation. The findings suggest that practice of adjustment of stride width and step length during walking are important.
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Straight and Curved Path Walking Among Older Adults in Primary Care: Associations With Fall-Related Outcomes
PM & R : the journal of injury function and rehabilitation, 2015Co-Authors: Sarah A. Welch, Jessie M. Vanswearingen, Jennifer S. Brach, Rachel E. Ward, Laura A. Kurlinski, Dan K. Kiely, Richard Goldstein, Jonathan F. BeanAbstract:Abstract Background Most falls among community-dwelling older adults occur while walking. Simple walking tests that require little resources and can be interpreted quickly are advocated as useful screening tools for fall prone patients. Objective To investigate 2 clinically feasible walking tests consisting of straight- and Curved-Path walking and examine their associations with history of previous falls and fall-related outcomes among community-living older adults. Design A cross-sectional analysis was performed on baseline data from a longitudinal cohort study. Setting Participants were recruited through primary care practices. Participants Participants included 428 primary care patients ≥65 years of age at risk for mobility decline. Participants had a median age of 76.5 years, 67.8% were women, and 82.5% were white. Methods Straight-Path walking performance was measured as the time needed to walk a 4-meter straight Path at usual pace from standstill using a stopwatch (timed to 0.1 second). Curved-Path walking performance was timed while participants walked from standstill in a figure-of-8 pattern around two cones placed 5 feet apart. Main Outcome Measurements Multivariable negative binomial regression analyses were performed to assess the relationship between straight-Path walking or Curved-Path walking and self-reported history of number of falls. For fall-related injuries, and fall-related hospitalizations, logistic regression models were used. Results In the fully adjusted model, an increase of 1 second in straight Path walking time was associated with 26% greater rate of falls (rate ratio 1.26, 95% confidence interval 1.10-1.45). An increase in Curved-Path walking time was associated with 8% greater rate of falls (rate ratio 1.08, 95% confidence interval=1.03-1.14). Neither walk test was associated with history of fall-related injuries or hospitalizations. Conclusions Poor performance on straight- and Curved-Path walking performance was associated with a history of greater fall rates in the previous year but not with a history of fall-related injuries or hospitalizations. This information helps inform how previous fall history is related to performance on walking tests in the primary care setting.
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a comparison of straight and Curved Path walking tests among mobility limited older adults
Journals of Gerontology Series A-biological Sciences and Medical Sciences, 2013Co-Authors: Charles A Odonkor, Jessie M. Vanswearingen, Jennifer S. Brach, Julia C Thomas, Nicole Holt, Nancy K Latham, Suzanne G Leveille, Alan M Jette, Jonathan F. BeanAbstract:Mobility limitations affect 25% of adults more than 65 years and impede walking and physical activity in this population (1). A number of studies suggest that limitations in mobility are of increasingly greater concern among elderly adults because this ability remains central to maintaining functional independence (2). Therefore, tools that allow for early screening of those at risk for decline in mobility and performance-based walking are indispensable for both geriatric research and clinical care (3). Key among these tools is habitual gait speed (HGS), a measure of straight-Path walking, and a predictor of subsequent morbidity and mortality (4). Another important measure and a recently validated test of walking skill, the figure-of-8 walking test (F8WT), is theorized to more accurately assess walking during activities that require navigating around Curved Paths and avoiding obstacles (5). Some reports indicate that F8WT and HGS performance may be linked to tests of executive function (5). However, most of the studies evaluating the attributes that underlie walking performance have been completed among relatively small samples (N < 150 participants) and have not directly compared HGS and the F8WT across a wide array of attributes that may influence performance (6). Consequently, it remains unclear whether the two tests reflect different health attributes that underlie mobility limitations among community-dwelling older adults. We therefore sought to compare the physiologic, cognitive, and health attributes underlying performance of HGS and F8WT to better understand how the two tests contrast. Direct comparison of the two tests allows us to better understand the relationships among the attributes that influence mobility performance among elderly adults. To address this aim, we conducted an analysis of baseline data collected as part of the Boston Rehabilitative Impairment Study of the Elderly (Boston RISE). Boston RISE is a prospective cohort study among 430 primary care patients aged 65 and older, who are at risk for mobility decline and disability. Because F8WT consists of both curvilinear and straight patterns of walking, we expected that the Boston RISE study results would help delineate the contexts of care in which the respective walking tests would be most useful.
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Contributions of Cognitive Function to Straight- and Curved-Path Walking in Older Adults
Archives of physical medicine and rehabilitation, 2012Co-Authors: Kristin A. Lowry, Jennifer S. Brach, Robert D. Nebes, Stephanie A. Studenski, Jessie M. VanswearingenAbstract:Abstract Lowry KA, Brach JS, Nebes RD, Studenski SA, VanSwearingen JM. Contributions of cognitive function to straight- and Curved-Path walking in older adults. Objective To determine whether the cognitive function contribution to straight- and Curved-Path walking differs for older adults. Design Cross-sectional observational study. Setting Ambulatory clinical research training center. Participants People (N=106) aged 65 to 92 years, able to walk household distances independently with or without an assistive device, and who scored 24 or greater on the Mini-Mental State Examination. Interventions Not applicable. Main Outcome Measures Cognitive function was assessed using the Digit Symbol Substitution Test (DSST) as a measure of psychomotor speed, and Trail Making Test Parts A and B (TMT-A and TMT-B) and the Trail Making Test difference score (TMT-B-A) as executive function measures of complex visual scanning and set shifting. Gait speed recorded over an instrumented walkway was used as the measure of straight-Path walking. Curved-Path walking was assessed using the Figure-of-8 Walk Test (F8W) and recorded as the total time and number of steps for completion. Results Both DSST and TMT-A independently contributed to usual gait speed ( P P P Conclusions Curved-Path walking, as measured by the F8W, involves different cognitive processes compared with straight-Path walking. Cognitive flexibility and set-shifting processes uniquely contributed to how individuals navigated Curved Paths. The measure of Curved-Path walking provides different and meaningful information about daily life walking ability than usual gait speed alone.
