Design and Analysis of Reduced Degree of Freedom Modular Snake Robot

2017 ◽  
Author(s):  
Peter Racioppo ◽  
Wael Saab ◽  
Pinhas Ben-Tzvi
Keyword(s):  
Three Dimensional ◽  
Cross Sectional ◽  
Design Synthesis ◽  
Snake Robot ◽  
Routing Schemes ◽  
Revolute Joints ◽  
Modular Units ◽  
A Chain ◽  
The Moment ◽  
And Control

This paper presents the design and analysis of an underactuated, cable driven mechanism for use in a modular robotic snake. The proposed mechanism is composed of a chain of rigid links that rotate on parallel revolute joints and are actuated by antagonistic cable pairs and a multi-radius pulley. This design aims to minimize the cross sectional area of cable actuated robotic snakes and eliminate undesirable nonlinearities in cable displacements. A distinctive feature of this underactuated mechanism is that it allows planar serpentine locomotion to be accomplished with only two modular units, improving the snake’s ability to conform to desired curvature profiles and minimizing the control complexity involved in snake locomotion. First, the detailed mechanism and cable routing scheme are presented, after which the kinematics and dynamics of the system are derived and a comparative analysis of cable routing schemes is performed, to assist with design synthesis and control. The moment of inertia of the mechanism is modeled, for future use in the implementation of three-dimensional modes of snake motion. Finally, a planar locomotion strategy for snake robots is devised, demonstrated in simulation, and compared with previous studies.

Synthesizing Mechanical Chains for Morphing Between Spatial Curves

2019 ◽  
Author(s):  
Yucheng Li ◽  
Andrew P. Murray ◽  
David H. Myszka
Keyword(s):  
Three Dimensional ◽  
Two Dimensions ◽  
Revolute Joints ◽  
Morphometric Analyses ◽  
Helical Segment ◽  
Varying Length ◽  
A Chain ◽  
Curvature And Torsion ◽  
Synthesis Methodology ◽  
Spatial Curves

Abstract This work investigates the kinematic synthesis methodology for designing a chain of three-dimensional bodies to match a set of arbitrary spatial curves. The bodies synthesized can be one of three types: a rigid segment, a helical segment with constant curvature and torsion but varying length, and a growth segment that maintains its geometry but may be scaled to become larger or smaller. To realize mechanical chains, only rigid and helical segments are used. After designing the segments, they may be aligned with the original spatial curves with their ends connected via an optimization. For two curves, these connections may be made with revolute joints to obtain high accuracy. For three or more curves, spherical joint connections allow for the best accuracy. To compare curves as is useful in morphometry, all three segment types may be employed. In this case, an accurate description of the changes between curves is important, and optimizing to connect the segments is not needed. The procedure for redefining the curves in a way that the techniques in this paper may be applied, as well as the methodologies for synthesizing the three segment types are presented. Examples include a continuum robot problem and the morphometric analyses of chochlear curves and the lambdoidal suture. This work extends the established planar techniques for synthesizing mechanisms and addressing morphometric issues that are motivated with curves in two-dimensions.

scholarly journals Characterization and Control for the Laminar Flow of Liquid Polyurethane System in a Wide Angle Diffuser with Transversely Arrayed Obstacles

2020 ◽  
Vol 10 (4) ◽  
pp. 1228
Author(s):  
Son ◽  
Lee ◽  
Chang
Keyword(s):  
Laminar Flow ◽  
Flow Velocity ◽  
Three Dimensional ◽  
Flow Uniformity ◽  
Cross Sectional ◽  
Lumped Parameter ◽  
Vorticity Vector ◽  
Rms Error ◽  
Sectional Shape ◽  
And Control

In the manufacturing process of hard-board poly-urethane foams, the uniformity is a very important issue for the raw compound of the liquid poly-urethane system flow for the quality control of such products. One of the universal methods to generate more uniform flow is that some obstacles are located inside the diffuser at the end of injector. For the regime of non-Newtonian laminar flow, better flow uniformity can be achieved with the enhancement of mixing in the wake after the resistive obstacles. In this research, the parametric study is made for the gap interval between adjacent obstacle components as well as the cross-sectional shape with a computational fluid dynamics (CFD) technique. The flow fields around circular and elliptic cylinders are visualized for flow velocity and vorticity with the comparison of root-mean-square (RMS) error for the deviation of velocity at the outlet as a lumped parameter to estimate flow uniformity and mixing. When the blockage ratio is fixed 0.3 for the pipe of Reynolds number 58.5 based on its diameter, eliminating the effect of wall boundary ratio with the classical Blasius velocity profile, the RMS error is reduced 77% to 92% from the baseline case in the case of 60%-diameter gaps for the figure of circles and 2:1 longitudinal ellipse, respectively. The flow is visualized around obstacle components with vorticity as well as flow velocity where the three-dimensional components of vorticity vector are also elucidated in physics for the evolution of complex multi-dimensional flow wake.

scholarly journals Position and Singularity Analysis of a Class of Planar Parallel Manipulators with a Reconfigurable End-Effector

Machines ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 7
Author(s):  
Tommaso Marchi ◽  
Giovanni Mottola ◽  
Josep M. Porta ◽  
Federico Thomas ◽  
Marco Carricato
Keyword(s):  
Inverse Kinematics ◽  
Kinematic Chain ◽  
Experimental Tests ◽  
Parallel Manipulators ◽  
Singularity Analysis ◽  
Parallel Robots ◽  
End Effector ◽  
Revolute Joints ◽  
A Chain ◽  
And Control

Parallel robots with configurable platforms are a class of robots in which the end-effector has an inner mobility, so that its overall shape can be reconfigured: in most cases, the end-effector is thus a closed-loop kinematic chain composed of rigid links. These robots have a greater flexibility in their motion and control with respect to rigid-platform parallel architectures, but their kinematics is more challenging to analyze. In our work, we consider n-RRR planar configurable robots, in which the end-effector is a chain composed of n links and revolute joints, and is controlled by n rotary actuators located on the base of the mechanism. In particular, we study the geometrical design of such robots and their direct and inverse kinematics for n=4, n=5 and n=6; we employ the bilateration method, which can simplify the kinematic analysis and allows us to generalize the approach and the results obtained for the 3-RRR mechanism to n-RRR robots (with n>3). Then, we study the singularity configurations of these robot architectures. Finally, we present the results from experimental tests that have been performed on a 5–RRR robot prototype.

scholarly journals Three-dimensional evaluation of upper airway changes following rapid maxillary expansion: A retrospective comparison with propensity score matched controls

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0261579
Author(s):  
Hussein Aljawad ◽  
Kyung-Min Lee ◽  
Hoi-Jeong Lim
Keyword(s):  
Propensity Score ◽  
Three Dimensional ◽  
Upper Airway ◽  
Rapid Maxillary Expansion ◽  
Control Group ◽  
Case Group ◽  
Maxillary Expansion ◽  
Cross Sectional ◽  
Skeletal Pattern ◽  
And Control

Background The aim of this study is to evaluate upper airway changes three-dimensionally following rapid maxillary expansion (RME) and compare the changes with matched controls. Materials and methods Seventeen patients (mean age 12.6 ± 1.8 years) with maxillary transverse deficiency were treated with RME. Using the propensity score matching method, 17 patients (mean age 12.3 ± 1.5 years) were selected from a non-RME control group of 33. Case-control matching was performed based on 5 covariates: age, gender, CBCT scan interval, sagittal skeletal pattern, and tongue posture. Airway volumes of nasopharynx and oropharynx and minimum cross-sectional areas (MCA) of oropharynx were measured and compared between the case and control groups in CBCT scan images. Results In the case group, significant increases from before to after RME were found in all measurements except MCA of the retroglossal segment of oropharynx. Before treatment, there were no significant differences between case group and control group. While comparing the case group with the control group after treatment showed overall greater increases in the case group. In particular, MCA of retropalatal segment showed statistically significant differences. Conclusion The results of this study indicate that RME causes an increase in upper airway dimensions.

X-Ray Replication of Submicrometer Linewidth Patterns

1977 ◽  
Vol 35 ◽  
pp. 136-137
Author(s):  
Henry I. Smith ◽  
D.C. Flanders
Keyword(s):  
Electron Beam Lithography ◽  
Cross Sectional ◽  
X Ray ◽  
Electron Backscattering ◽  
Spatial Frequencies ◽  
Cross Sectional Profile ◽  
Carbon Foils ◽  
Sectional Profile ◽  
And Control ◽  
Soft Radiation

Scanning electron beam lithography has been used for a number of years to write submicrometer linewidth patterns in radiation sensitive films (resist films) on substrates. On semi-infinite substrates, electron backscattering severely limits the exposure latitude and control of cross-sectional profile for patterns having fundamental spatial frequencies below about 4000 Å(l),Recently, STEM'S have been used to write patterns with linewidths below 100 Å. To avoid the detrimental effects of electron backscattering however, the substrates had to be carbon foils about 100 Å thick (2,3). X-ray lithography using the very soft radiation in the range 10 - 50 Å avoids the problem of backscattering and thus permits one to replicate on semi-infinite substrates patterns with linewidths of the order of 1000 Å and less, and in addition provides means for controlling cross-sectional profiles. X-radiation in the range 4-10 Å on the other hand is appropriate for replicating patterns in the linewidth range above about 3000 Å, and thus is most appropriate for microelectronic applications (4 - 6).

ROLE OF PHARMACIST INTERVENTION ON COPD PATIENTS OF SELECTED AREAS IN CHITRADURGA: A KAP STUDY

2019 ◽  
Vol 8 (2) ◽  
Author(s):  
Melvin K Mathews ◽  
Abubaker Siddiq ◽  
Bharathi D R
Keyword(s):  
Illness Perceptions ◽  
Pharmacist Intervention ◽  
Cross Sectional Study ◽  
Chronic Obstructive ◽  
Cross Sectional ◽  
Obstructive Pulmonary Disease ◽  
Copd Patients ◽  
Post Test ◽  
Knowledge Practice ◽  
And Control

Background: Chronic obstructive pulmonary disease (COPD) is preventable and treatable disease state characterized by air flow limitation that is not fully reversible. Severity of the symptoms is increased during exacerbations. Objectives: The purpose of the study is to assess and improve the knowledge regarding COPD among study subjects. Materials and Methods: A Cross-sectional interventional study was carried out among the peoples in selected areas of the Chitradurga city for a period of six months. Result: A total 207 subjects enrolled in the study in that 155 male and 52 females. In our study mean score of post test was more (5.87±1.68) when compare to pre-test (2.63±1.46) which show significant increase in their knowledge after educating them (p=0.000). A total of 207 subjects were enrolled into the study. SPSS Software was used to calculate the statistical estimation. Paired t-test was used to detect the association status of different variables. Conclusion: The relatively good level of COPD awareness needs to be maintained to facilitate future prevention and control of the disease. This study had identified that negative illness perceptions should be targeted, so that they will not avoid patients from seeking for COPD treatment and adhere to it. Key words: Cross sectional study, Knowledge, practice, COPD.

Hubungan Antara Menyusui Dengan Involusi Uterus Pada Ibu Nifas Fisiologis Di RSIA Aura Syifa Kabupaten Kediri

1970 ◽  
Vol 5 (2) ◽  
pp. 64
Author(s):  
Eny Sendra ◽  
Dewi Indriani
Keyword(s):  
Breast Feeding ◽  
Sampling Technique ◽  
Chi Square ◽  
Cross Sectional ◽  
Fisher Test ◽  
Key Word ◽  
Chi Square Test ◽  
The Moment

Breast feeding is giving milk to be drunk to the baby from the breast. Uterus involution is a process how the uterus return to the condition back, before pregnanting after bearing. At the moment of suckling, happens a stimulus and brings the hormones out, such as oksitosin uses not only to stimulate some muscles constraction but also to stimulate the uterus, so that the process of uterus involution happens foster. According to the explanations above, the research aimed to know about the correlation between breast feeding and uterus involution. This research’s design was, cross sectional by the population of all childbirth mothers approximately 50 persons / month. By using accidental sampling technique we got 21 sample respondents. The place of research in RSIA Aura Syifa in Kediri Regency on 16th until 22nd of June 2009. From this research’s result, we got 14 persons (66,67%) with normal uterus involution, suckled in a good way, one person (4,67%) with normal uterus involution, suckled in a wrong way, 2 persons (9,52%) with abnormal uterus involution, suckled in a good way and 4 persons (19,05%) with abnormal uterus involution, suckled in a wrong way. Statistic test which used chi-square test, counted the probability frequency in advance, from that we got 3 columns with the score, less than 5, so that chi-square can not be continued and by doing exact fisher test, the score was 0,001. Because P with the grade mistake 0,05 smaller, so the conclusion was “Ho” is rejected, it meant “there was correlation between suckling and uterus involution”. Key Word : Breast feeding, uterus involution

Cut off value of plasma 25-hydroxyvitamin D concentration for predicting metabolic syndrome

2019 ◽  
pp. 68-73
Author(s):  
Trong Nghia Nguyen ◽  
Thi Nhan Nguyen ◽  
Thi Dua Dao
Keyword(s):  
Metabolic Syndrome ◽  
Medical Center ◽  
Cross Sectional Study ◽  
Control Group ◽  
Cross Sectional ◽  
Hydroxyvitamin D ◽  
The Metabolic Syndrome ◽  
25 Hydroxyvitamin D ◽  
Key Words Metabolic Syndrome ◽  
And Control

Background: The metabolic syndrome is a constellation of cardiometabolic risk factors that tend to cluster together in affected individuals more often than predicted by chance. The presence of the metabolic syndrome substantially increases the risk of developing type 2 diabetes and cardiovascular disease, and is associated with a range of adverse clinical outcomes, many of which are closely associated with aging. Current estimates suggest that approximately 20 - 25% of the world’s population is affected by the metabolic syndrome. The prevalence of the metabolic syndrome rises with age and more than 45% of people aged over 60 years have the metabolic syndrome. Recent studies show that low vitamin D status is very common in the world and this is a risk factor of metabolic syndrome. Objective: (1) Plasma 25-hydroxyvitamin D concentration in subjects with metabolic syndrome. (2) Cut off value of plasma 25-hydroxyvitamin D concentration for predicting metabolic syndrome. Material and method: A cross-sectional study with control group on 318 adult subjects for health examinations at International Medical Center at Hue Central Hospital, including 139 subjects with metabolic syndrome and control group of 179 healthy subjects. Metabolic syndrome was defined according to the IDF, NHLBI, AHA, WHF, IAS, IASO (2009). Plasma hydroxyvitamin D concentration was measured using chemiluminescent microparticle immunoassay. Reciever operating characteristic (ROC) curve were generated to assess sensitivity and specificity for different cut off value of 25-hydroxyvitamin D concentration for predicting metabolic syndrome. Results: Plasma 25-hydroxyvitamin D concentration in subjects with metabolic syndrome was 26.4 ng/ml, incidence of plasma 25-hydroxyvitamin D deficiency (59.7%) was significantly higher than in control group (23.5%) (p < 0.001). The optimal cut off point for 25-OH-D concentration for predictor of metabolic syndrome as 26.4 ng/ml (AUC=0.657, sensitivity=53.4%, specificity=71.6%). Conclusion: In 139 subjects with metabolic syndrome, the plasma 25-hydroxyvitamin D concentration was 26.4 ng/ml and the incidence of 25-hydroxyvitamin D deficiency in the metabolic syndrome group was 59.7%. The optimal cut off point for plasma 25-hydroxyvitamin D concentration for predictor of metabolic syndrome as 26.4 ng/ml. Key words: Metabolic syndrome, 25-hydroxyvitamin D

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