The kinematics of curved profiles mating with a caged idle roller - higher-path curvature analysis

2021 ◽  
Vol 164 ◽  
pp. 104414
Author(s):  
M. Cera ◽  
M. Cirelli ◽  
E. Pennestrì ◽  
P.P. Valentini
Keyword(s):  
Curvature Analysis ◽  
Path Curvature

Higher Path-Curvature Analysis in Plane Kinematics

1965 ◽  
Vol 87 (2) ◽  
pp. 184-190 ◽  
Author(s):  
F. Freudenstein
Keyword(s):  
Kinematic Analysis ◽  
Algebraic Curve ◽  
Point Contact ◽  
Rates Of Change ◽  
Curvature Analysis ◽  
Synthesis Of Mechanisms ◽  
Analysis And Synthesis ◽  
Path Curvature ◽  
Motion Characteristics

Classical kinematics furnishes us with powerful techniques for the determination of the motion characteristics of a rigid body, or “plane,” or link. The present analysis is concerned more with the motion characteristics of the path generated by a point on a link, rather than with the link as a whole. For four infinitesimal displacements, it is shown that the locus of all points on a link with a prescribed ratio of path-evolute curvature to path curvature is a higher algebraic curve, the “quartic of derivative curvature.” For five infinitesimal displacements, five points on a moving link can in general be found having five-point contact with an arbitrary, prescribed curve. For circular motion, these results reduce to the classical theories of Burmester and Mueller. Equations have been derived for the first and second rates of change of path curvature in terms of the evolutes to the path. The results are applicable to the kinematic analysis and synthesis of mechanisms and are illustrated, specifically, for the generation of involute, parabolic, and elliptic arcs.

Engagement time constrained formation generation guidance following a non-manoeuvring leader

2020 ◽  
Vol 234 (8) ◽  
pp. 1414-1432
Author(s):  
Shalini Suresh ◽  
Ashwini Ratnoo
Keyword(s):  
Equilibrium Point ◽  
Vehicle Dynamics ◽  
Direct Method ◽  
Lyapunov Direct Method ◽  
Speed Limits ◽  
Extensive Simulation ◽  
Curvature Analysis ◽  
Path Curvature ◽  
Turn Rate ◽  
Simulation Exercises

This paper addresses the problem of formation generation of two UAVs with constraints on engagement time. A leader–follower scenario with the leader being non-manoeuvring is considered. The work uses track guidance method for generating a class of follower spatial paths and combines it with a speed profile that works to minimize the error with respect to the desired follower position. Path curvature analysis is carried out and set of feasible spatial paths which abide by the UAV turn rate constraint is obtained. The equilibrium point of the resulting nonlinear system is found to be the desired formation geometry and stability analysis using Lyapunov direct method guarantees convergence to the equilibrium point. The set of achievable engagement times is deduced with closed-form limits. Extensive simulation exercises are carried out incorporating follower speed limits, wind and vehicle dynamics, and presence of obstacles. The work highlights a flexible guidance method which effectively uses one design parameter and analytic conditions for formation generation.

scholarly journals Initial Clinical Experience With a New Conformable Abdominal Aortic Endograft: Aortic Neck Coverage and Curvature Analysis in Challenging Aortic Necks

2021 ◽  
pp. 152660282199672
Author(s):  
Alice Finotello ◽  
Richte Schuurmann ◽  
Sara Di Gregorio ◽  
Gian Antonio Boschetti ◽  
Nabil Chakfé ◽  
...  
Keyword(s):  
Aortic Wall ◽  
Surface Coverage ◽  
Infrarenal Aorta ◽  
Technical Success ◽  
Curvature Analysis ◽  
Average Curvature ◽  
Aortic Neck ◽  
Abdominal Aortic ◽  
Shortest Distance ◽  
New Generation

Objectives: Aim of this work was to investigate precision of deployment and conformability of a new generation GORE EXCLUDER Conformable Endoprosthesis with active control system (CEXC Device, W.L. Gore and Associates, Flagstaff, AZ, USA) by analyzing aortic neck coverage and curvature. Methods: All consecutive elective patients affected by abdominal aortic aneurysm or aortoiliac aneurysm treated at our institution between November 2018 and June 2019 with the new CEXC Device were enrolled. Validated software was adopted to determine the available apposition surface area into the aortic neck, apposition of the endograft to the aortic wall, shortest apposition length (SAL), shortest distance between the endograft fabric and the lowest renal arteries (SFD) and between the endograft fabric and the contralateral renal artery (CFD). Pointwise centerline curvature was also computed. Results: Twelve patients (10 men, median age 78 years (71.75, 81.0)) with available pre- and postoperative computed tomography angiography (CTA) were included. Technical success was obtained in all the cases. Preoperative median length of the proximal aortic neck was 16.1 mm (10.7, 21.7) and suprarenal (α) and infrarenal (β) neck angulation were, respectively, 28.9° (15.7°, 47.5°) and 75.0° (66.9°, 81.4°). Postoperative median apposition surface coverage was 79% (69.25%, 90.75%) of the available apposition surface. SFD and CFD were 1.5 mm (0.75, 5.25) and 7 mm (4.5, 21.5), respectively. Average curvature over the infrarenal aorta decreased from 25 m−1 (21.75, 29.0) to 22.5 m−1 (18.75, 24.5) postoperatively (p=0.02). Maximum curvature did not decrease significantly from 64.5 m−1 (54.25, 92.0) to 62 m−1 (41.75, 71.5) (p=0.1). Conclusions: Our early experience showed that deployment of the CEXC Device is safe and effective for patients with challenging proximal aortic necks. Absence of significant changes between pre- and postoperative proximal aortic neck angulations and curvature confirms the high conformability of this endograft.

scholarly journals Experimental Investigation on the Influence of Fiber Path Curvature on the Mechanical Properties of Composites

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2602
Author(s):  
Huaqiao Wang ◽  
Jihong Chen ◽  
Zhichao Fan ◽  
Jun Xiao ◽  
Xianfeng Wang
Keyword(s):  
Tensile Strength ◽  
Path Planning ◽  
Composite Laminates ◽  
Bending Strength ◽  
High Strength ◽  
Bending Test ◽  
Fiber Placement ◽  
Automated Fiber Placement ◽  
Fiber Path ◽  
Path Curvature

Automated fiber placement (AFP) has been widely used as an advanced manufacturing technology for large and complex composite parts and the trajectory planning of the laying path is the primary task of AFP technology. Proposed in this paper is an experimental study on the effect of several different path planning placements on the mechanical behavior of laminated materials. The prepreg selected for the experiment was high-strength toughened epoxy resin T300 carbon fiber prepreg UH3033-150. The composite laminates with variable angles were prepared by an eight-tow seven-axis linkage laying machine. After the curing process, the composite laminates were conducted by tensile and bending test separately. The test results show that there exists an optimal planning path among these for which the tensile strength of the laminated specimens decreases slightly by only 3.889%, while the bending strength increases greatly by 16.68%. It can be found that for the specific planning path placement, the bending strength of the composite laminates is significantly improved regardless of the little difference in tensile strength, which shows the importance of path planning and this may be used as a guideline for future AFP process.

Path Curvature in Workspace and in Joint Space: Evidence for Coexisting Coordinative Rules in Aiming

Motor Control ◽  
1998 ◽  
Vol 2 (4) ◽  
pp. 331-351 ◽  
Author(s):  
Edwin Van Thiel ◽  
Ruud G.J. Meulenbroek ◽  
Wouter Hulstijn
Keyword(s):  
Joint Space ◽  
Line Production ◽  
Vertical Movements ◽  
Space Planning ◽  
Aiming Movements ◽  
Trajectory Formation ◽  
Straight Line ◽  
Bottom Left ◽  
Path Curvature ◽  
Point To Point

In this study we tried to establish whether point-to-point aiming movements are planned in workspace, joint space, or both. Eight right-handed subjects performed horizontal, vertical, and diagonal aiming movements on a transversal plane. Movements were performed at several speeds. Curvature variations of the hand and corresponding joint-space paths were investigated as a function of position, direction, and speed. Straightness of hand paths predominated for vertical movements but was systematically violated for horizontal and top-right to bottom-left movements. Furthermore, the hand-path curvature of the latter movements increased with speed. Joint-space paths showed more deviation from a straight line than hand paths except for top-left to bottom-right movements in which the paths were equally curved. A comparison of normalized path curvatures at the hand and joint level indicated that in aiming, the coordinative rule of straight-line production seems to apply to both workspace and joint-space planning. The present findings confirm Kawato's (1996) views that optimization processes operate concurrently at the two control levels of arm-trajectory formation under study.

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