bluuebunny/crossref_metadata_2025_split huggingface dataset:
Line-of-Sight Pure Pursuit Guidance Stability Analysis and Design Guideline for Car-Like Autonomous Ground Vehicles
Authors: Lin Letian , Zhu J. Jim 
Published: November 2019

Abstract
Pure pursuit guidance (PPG) has been used to solve the path following problem for car-like autonomous ground vehicles (CAGV). Most of the PPG guidance laws for CAGV guide the vehicle to follow a circular arc connecting the vehicle with a virtual target point on the path at a specified distance ahead of the vehicle, which could be called ARC PPG. Another type of PPG law for CAGV guides the vehicle by steering its velocity vector to align with the line-of-sight (LOS) connecting the vehicle and the virtual target. While some qualitative stability results exist on ARC PPG for some special types of curves of the path, such as straight and circular, a quantitative stability analysis on general paths is highly desirable but appears missing. Moreover, the existing guidance parameter selection methods depend highly on empirical tuning. In this work, the LOS PPG formulation is used to obtain a rigorous quantitative stability result stated as two theorems for general reference paths by treating the path curvature as a non-vanishing perturbation in a nonlinear context. The result shows that the ARC PPG is a special case of the LOS PPG, whereby establishing the generality of the theorems for PPG of CAGVs. Moreover, a geometric interpretation of the guidance parameters in relation to the path curvature is provided. By using the results of the stability analysis, a practical design guideline for LOS PPG is presented. Simulation results are shown to demonstrate the correctness of the stability analysis and the usefulness of the design guideline.
Towards Cooperative Transportation of Multiple Mecanum-Wheeled Automated Guided Vehicles
Authors: Peng Jih-Sien , Liu Yen-Chen 
Published: November 2019

Abstract
Utilizing multiple small-sized automated guided vehicles (AGVs) in cooperatively transport large and heavy objects in manufacturing factories or logistics is an emerging research direction. Flexibility and efficiency can be enhanced by using multi-AGV comparing to a large AGV with higher capacity especially in clutter environments. In this paper, a multi-AGV system by using Mecanum wheels to provide omnidirectional movement is proposed for cooperative transportation. Accordingly, the proposed Mecanum-wheeled automated guided vehicles (MWAGVs) composed of Mecanum wheels and a rotary platform provides not only non-constrained movement but also planar displacement for allowance of distance errors. In the proposed MWAGVs, the formation control with fixed geometry during operation is significant especially with unknown object information, dynamic uncertainties, and external disturbances. Therefore, the passivity-based adaptive synchronizing control algorithm is developed to ensure stability and tracking performance with uncertain dynamic parameters. Simulations and Experiments show the efficacy of designed Mecanum-wheeled AGV.
Experimental Validations on Vision-Based Path Tracking With Preview Four Wheel Steering Control
Authors: Peng Yansong , Wang Fengchen , Gurumoorthy Saikrishna , Chen Yan , Xin Mutian 
Published: November 2019

Abstract
In this paper, a vision-based path-tracking control strategy using four-wheel steering (4WS) is experimentally investigated via an automated ground vehicle (AGV). A low-cost monocular camera is used to continuously perceive the upcoming lane boundaries via capturing the preview road image frames. Based on the applied image processing algorithms, the vehicle lateral offset error with respect to the road center line and the heading angle error with respect to the road curvature are calculated in real time for the control purpose. The 4WS path-tracking controller is designed to minimize the two path-tracking errors of the AGV. The AGV with the 4WS system is utilized to perform the experimental tests on road to validate the path-tracking control design. For comparison, the road test is also conducted for the path-tracking control with only the front wheel steering. The experimental results show that the proposed 4WS is able to achieve better path-tracking performance.
Model Reference Control With Command Shaping for a Micro-Electromagnetic Actuator With Input Constraints
Authors: Eaglin Gerald , Vaughan Joshua 
Published: November 2019

Abstract
Model Reference Control is used to force a system to track the response of an assigned reference model, where the reference model is often designed to reflect the desired properties of the system. If a linear reference model is used, Model Reference Control has a linearizing effect for nonlinear plants, allowing it to be cascaded with linear controllers. Model Reference Control has been used to force nonlinear flexible systems to behave linearly such that input shaping can be used to limit residual vibration. However, when a system encounters saturation limits, the vibration limiting property of input shaping is degraded. This paper proposes Model Reference Control with an adaptive input shaping method to account for saturation by modifying the input shaper after saturation has been encountered. Simulations are presented to illustrate the effectiveness of this method in canceling residual vibration for a nonlinear electromagnetic actuator subject to input constraints.
Flight Dynamics and Control of a Farm of Tethered Energy Systems in a Turbulent Field
Authors: Siddiqui Ayaz , Ramaprabhu Praveen , Deese Joe , Vermillion Chris 
Published: November 2019

Abstract
In this paper, we present a combined flight dynamic, control system, and wake interaction model for an array (farm) of tethered energy systems, assessing the response of the array to a turbulent incoming flow field. The model presented herein constitutes the most detailed farm-level dynamic model for tethered energy systems to-date. In particular, the model accounts for more realistic approximations of tether dynamics and added mass effects, while characterizing the ability to control the system through both tethers and control surfaces. Focusing on a specific design and array geometry for ocean current energy harvesting, we analyze the dynamic performance of the array under a turbulent flow field that is representative of the turbulent environment in the Gulf Stream. We perform a frequency domain analysis of individual tethered systems in order to better understand the attenuation properties of the modeled system.
Path Following for the Soft Origami Crawling Robot
Authors: Angatkina Oyuna , Gustafson Kimberly , Wissa Aimy , Alleyne Andrew 
Published: November 2019

Abstract
Extensive growth of the soft robotics field has made possible the application of soft mobile robots for real world tasks such as search and rescue missions. Soft robots provide safer interactions with humans when compared to traditional rigid robots. Additionally, soft robots often contain more degrees of freedom than rigid ones, which can be beneficial for applications where increased mobility is needed. However, the limited number of studies for the autonomous navigation of soft robots currently restricts their application for missions such as search and rescue.
This paper presents a path following technique for a compliant origami crawling robot. The path following control adapts the well-known pure pursuit method to account for the geometric and mobility constraints of the robot. The robot motion is described by a kinematic model that transforms the outputs of the pure pursuit into the servo input rotations for the robot. This model consists of two integrated sub-models: a lumped kinematic model and a segmented kinematic model. The performance of the path following approach is demonstrated for a straight-line following simulation with initial offset. Finally, a feedback controller is designed to account for terrain or mission uncertainties.
Combining Reachability Analysis and Importance Sampling for Accelerated Evaluation of Highly Automated Vehicles at Pedestrian Crossing
Authors: Wang Xinpeng , Peng Huei , Zhao Ding 
Published: November 2019

Abstract
Publisher’s Note:
This paper was selected for publication in ASME Letters in Dynamic Systems and Control.
https://www.asmedigitalcollection.asme.org/lettersdynsys/article/doi/10.1115/1.4046610/1075844/Combining-Reachability-Analysis-and-Importance
Dynamic Control of Soft Robots Using Reinforcement Learning
Authors: Pawlowski Ben , Anderson Charles W. , Zhao Jianguo 
Published: November 2019

Abstract
Soft robots made from soft materials recently attracted tremendous research owing to their unique softness compared with rigid robots, making them suitable for applications such as manipulation and locomotion. However, also due to their softness, the modeling and control of soft robots present a significant challenge because of the infinite degree of freedom. In this case, although analytic solutions can be derived for control, they are too computationally intensive for real-time application. In this paper, we aim to leverage reinforcement learning to approach the control problem. We gradually increase the complexity of the control problems to learn. We also test the effectiveness and efficiency of reinforcement learning techniques to the control of soft robots for different tasks. Simulation results show that the control commands to be computed in milliseconds, allowing effective control of soft manipulators, up to trajectory tracking.
Safe, Aggressive Quadrotor Flight via Reachability-Based Trajectory Design
Authors: Kousik Shreyas , Holmes Patrick , Vasudevan Ram 
Published: November 2019

Abstract
Quadrotors can provide services such as infrastructure inspection and search-and-rescue, which require operating autonomously in cluttered environments. Autonomy is typically achieved with receding-horizon planning, where a short plan is executed while a new one is computed, because sensors receive limited information at any time. To ensure safety and prevent robot loss, plans must be verified as collision free despite uncertainty (e.g, tracking error). Existing spline-based planners dilate obstacles uniformly to compensate for uncertainty, which can be conservative. On the other hand, reachability-based planners can include trajectory-dependent uncertainty as a function of the planned trajectory. This work applies Reachability-based Trajectory Design (RTD) to plan quadrotor trajectories that are safe despite trajectory-dependent tracking error. This is achieved by using zonotopes in a novel way for online planning. Simulations show aggressive flight up to 5 m/s with zero crashes in 500 cluttered, randomized environments.
Switched Linear Model of a Stratified Hot Water Tank for Control of Micro-CHP Systems
Authors: Bird Trevor , Weaver Catherine , Jain Neera 
Published: November 2019

Abstract
We present a switched linear system approach for modeling the complex nonlinear dynamics associated with temperature inversion occurring in thermally stratified hot water tanks. Such tanks are commonly used for thermal energy storage, particularly in low- to medium-temperature waste heat recovery applications. By separating the influence of temperature inversion from the internal heat transfer between states in the governing differential equations, we paramaterize the nonlinearity using a vector of discrete variables. This vector is then used to define the switching between a set of linear, discrete time models. The proposed switched model is validated against a reduced-order nonlinear model of the thermal energy storage and then integrated with a fuel cell model to capture the dynamics of a micro-combined heat and power system. Simulation results demonstrate the importance that temperature inversion has on the stratification dynamics which in turn has implications for control of such systems.
On Receding Horizon Chance Constraint Motion Planning for Uncertain Multi-Agent Systems
Authors: Bagla Yash , Srivastava Vaibhav 
Published: November 2019

Abstract
We propose and study a motion planning algorithm for multi-agent autonomous systems to navigate through uncertain and dynamic environments. We use a receding horizon chance constraint framework that allows for tuning the trade-off between the risk of collision and the infeasibility of paths. We consider sampling-based incremental planning algorithms and extend them to the case of multiple agents and dynamic and uncertain environments. The receding horizon control framework is used to incorporate sensor measurements at a fixed interval of time to reduce uncertainty about agents’ state and environment. Our presentation focuses on rapidly-exploring random trees (RRTs) and the assumption of Gaussian noise in the uncertainty model. Our algorithm is illustrated using several examples.
Regional multidisciplinary team intervention programme to improve colorectal cancer outcomes: study protocol for the Yorkshire Cancer Research Bowel Cancer Improvement Programme (YCR BCIP)
Authors: Taylor John , Wright Penny , Rossington Hannah , Mara Jackie , Glover Amy , West Nick , Morris Eva , Quirke Phillip 
Published: November 2019

IntroductionAlthough colorectal cancer outcomes in England are improving, they remain poorer than many comparable countries. Yorkshire Cancer Research has, therefore, established a Bowel Cancer Improvement Programme (YCR BCIP) to improve colorectal cancer outcomes within Yorkshire and Humber, a region representative of the nation. It aims to do this by quantifying variation in practice, engaging with the colorectal multidisciplinary teams (MDTs) to understand this and developing educational interventions to minimise it and improve outcomes.Methods and analysisInitially, routine health datasets will be used to quantify variation in the demographics, management and outcomes of patients across the Yorkshire and Humber region and results presented to MDTs. The YCR BCIP is seeking to supplement these existing data with patient-reported health-related quality of life information (patient-reported outcome measures, PROMs) and tissue sample analysis. Specialty groups (surgery, radiology, pathology, clinical oncology, medical oncology, clinical nurse specialists and anaesthetics) have been established to provide oversight and direction for their clinical area within the programme, to review data and analysis and to develop appropriate educational initiatives.Ethics and disseminationThe YCR BCIP is aiming to address the variation in practice to significantly improve colorectal cancer outcomes across the Yorkshire and Humber region. PROMs and tissue sample collection and analysis will help to capture the information required to fully assess care in the region. Engagement of the region’s MDTs with their data will lead to a range of educational initiatives, studies and clinical audits that aim to optimise practice across the region.
Do BRCA1 and BRCA2 gene mutation carriers have a reduced ovarian reserve? Protocol for a prospective observational study
Authors: Winship Amy Louise , Willson Chris , Hansen Karl R , Hutt Karla J , Hickey Martha 
Published: November 2019

IntroductionBRCA1/2 gene mutations increase risk of breast and/or ovarian cancer and may have implications for reproductive health. Indirect biomarkers of the ovarian primordial follicle pool (anti-Müllerian hormone (AMH)) and one small study in female cadavers suggest that ovarian reserve may be reduced in BRCA mutation carriers, but findings are conflicting and association between circulating AMH and primordial follicle number is not established. The aim of this study is to measure primordial follicle density in premenopausal ovarian tissue samples from women with BRCA1/2 gene mutations versus age-matched comparison group.Methods and analysisProspective observational study measuring associations between BRCA gene mutation status, premenopausal ovarian primordial follicle density and serum AMH concentrations versus age-matched premenopausal women from the general population. Primordial follicle density will be measured in cortical sections from ovarian tissue collected at the time of risk-reducing bilateral salpingo-oophorectomy (RRBSO) in 88 BRCA1 gene mutation carriers, 65 BRCA2 gene mutation carriers and 157 non-mutation carriers. Primordial follicle density will be determined by counting follicles in a known volume of ovarian cortical tissue using light microscopy. Follicles will be identified by immunohistochemical staining for oocyte marker mouse vasa homologue. To inform the mechanisms underlying reduced ovarian reserve, the proportion of follicles containing oocytes with DNA damage will be determined by immunohistochemical staining for phosphorylated histone H2AX and terminal deoxynucleotidyl transferase dUTP nick end labelling assay to identify apoptotic cells. Follicle density will be correlated with circulating AMH concentrations quantified in the same cohort, using an electrochemiluminescence immunoassay on an automated platform.Ethics and disseminationEthics approval has been granted by Peter MacCallum Cancer Centre to access biobanks, including; The Kathleen Cuningham Foundation Consortium for Research into Familial Breast Cancer (kConFab-HREC#97_27) and the What Happens after Menopause? (HREC12PMCC24-12/90) and Melbourne IVF.
Psychometric properties of the global rating of change scales in patients with neck disorders: a systematic review with meta-analysis and meta-regression
Authors: Bobos Pavlos , MacDermid Joy , Nazari Goris , Furtado Rochelle 
Published: November 2019

ObjectiveThe purpose of this systematic review was to critically appraise and synthesise the psychometric properties of Global Rating of Change (GROC) scales for assessment of patients with neck pain.DesignSystematic review.Data sourcesA search was performed in four databases (MEDLINE, EMBASE, CINAHL, SCOPUS) until February 2019.Data extraction and synthesisEligible articles were appraised using Consensus-based Standards for the selection of health Measurement Instruments checklist and the Quality Appraisal for Clinical Measurement Research Reports Evaluation Form.ResultsThe search obtained 16 eligible studies and included in total 1533 patients with neck pain. Test–retest reliability of global perceived effect (GPE) was very high (intraclass correlation coefficient=0.80 to 0.92) for patients with whiplash. Pooled data of Pearson’s r indicated that GROC scores were moderately correlated with neck disability change scores (0.53, 95% CI: 0.47 to 0.59). Pooled data of Spearman’s correlations indicated that GROC scores were moderately correlated with neck disability change scores (0.56, 95% CI: 0.41 to 0.68).ConclusionsThis study found excellent quality evidence of very good-to-excellent test–retest reliability of GPE for patients with whiplash-associated disorders. Evidence from very good-to-excellent quality studies found that GROC scores are moderately correlated to an external criterion patient-reported outcome measure evaluated pre-post treatment in patients with neck pain. No studies were found that addressed the optimal form of GROC scales for patients with neck disorders or compared the GROC to other options for single-item global assessment.PROSPERO registration numberCRD42018117874.
Patients with low Alberta Stroke Program Early CT Score (ASPECTS) but good collaterals benefit from endovascular recanalization
Authors: Broocks Gabriel , Kniep Helge , Schramm Peter , Hanning Uta , Flottmann Fabian , Faizy Tobias , Schönfeld Michael , Meyer Lukas , Schön Gerhard , Aulmann Linda , Machner Björn , Royl Georg , Fiehler Jens , Kemmling Andre 
Published: November 2019

BackgroundBenefit of thrombectomy in patients with a low initial Alberta Stroke Program Early CT Score (ASPECTS) is still uncertain. We hypothesized that, despite low ASPECTS, patients may benefit from endovascular recanalization if good collaterals are present.MethodsIschemic stroke patients with large vessel occlusion in the anterior circulation and an ASPECTS of ≤5 were analyzed. Collateral status (CS) was assessed using a 5-point-scoring system in CT angiography with poor CS defined as CS=0–1. Clinical outcome was determined using the modified Rankin Scale (mRS) score after 90 days. Edema formation was measured in admission and follow-up CT by net water uptake.Results27/100 (27%) patients exhibited a CS of 2–4. 50 patients underwent successful vessel recanalization and 50 patients had a persistent vessel occlusion. In multivariable logistic regression analysis, collateral status (OR 3.0; p=0.003) and vessel recanalization (OR 12.2; p=0.009) significantly increased the likelihood of a good outcome (mRS 0–3). A 1-point increase in CS was associated with 1.9% (95% CI 0.2% to 3.7%) lowered lesion water uptake in follow-up CT .ConclusionEndovascular recanalization in patients with ASPECTS of ≤5 but good collaterals was linked to improved clinical outcome and attenuated edema formation. Collateral status may serve as selection criterion for thrombectomy in low ASPECTS patients.
Intracranial venous sinus stenosis: hemodynamic assessment with two-dimensional parametric parenchymal blood flow software on digital subtraction angiography
Authors: Almadidy Zayed , Brunozzi Denise , Nelson Jessica , Baumgart John , Atwal Gursant , Alaraj Ali 
Published: November 2019

ObjectiveIntracranial venous sinus stenosis (IVSS) is the most common finding associated with idiopathic intracranial hypertension. A pressure gradient >8–10 mm Hg across the stenosis is considered hemodynamically significant, and typically responds to endovascular stent treatment. Here we assess the venous hemodynamics with two-dimensional (2D) parametric parenchymal blood flow software (Siemens-Healthineers, Forchheim, Germany) and its ability to predict significant IVSS.MethodsPatients with IVSS treated at our institution between 2013 and 2018 were retrospectively reviewed. Measurements of contrast transit time on DSA were calculated with 2D parametric parenchymal blood flow software. Values were obtained proximally and distally to the stenotic region. Venous Stenosis Index (VSI) was defined as the ratio of the area under the curve (AUC) in the pre-stenotic vessel to the AUC in the post-stenotic vessel. VSI was compared between the stenotic and control groups at baseline, and before and after stent deployment in the stenotic group. The accuracy of VSI was assessed using the non-parametric receiver operating characteristic (ROC) curve.Results11 patients with IVSS treated with venous stent deployment were included. Patients in the control group were similar in age, gender, and absence of major comorbidities. VSI in the IVSS group was significantly higher at baseline compared with the control group (1.42 vs 0.97, p=0.01). Area under the ROC was 0.82. After stent deployment, VSI decreased significantly compared with baseline (1.04 vs 1.42, p<0.01).Conclusion2D parametric parenchymal blood flow software is a useful tool which can accurately evaluate significant hemodynamic venous stenosis without intracranial catheterization, added radiation exposure, additional contrast injection, and periprocedural risks.
Pea pollen viability and seed set response at high night temperatures
Authors: Jiang Yunfei , Davis Arthur R. , Warkentin Thomas D. , Bueckert Rosalind A. 
Published: November 2019

Field pea (Pisum sativum L.), a major pulse crop in western Canada, is sensitive to elevated temperature and possibly to high night temperature. Our objective was to examine if increasing night temperature while maintaining a constant daytime temperature affected pollen viability and seed set in two pea cultivars (CDC Golden and CDC Sage). Cultivars were exposed to 27/18, 27/22, 27/26 °C (day/night temperatures) for 7 d during flowering stage. Results indicated that increased night temperatures had no significant effect on pollen viability, the number of reproductive nodes and flowers, percentage of flower abortion, seed number per pod, and seed yield per plant.