Three-dimensional dynamic surface grasping with dry adhesion

2015 ◽  
Vol 35 (8) ◽  
pp. 943-958 ◽  
Author(s):  
Elliot W. Hawkes ◽  
Hao Jiang ◽  
Mark R. Cutkosky
Keyword(s):  
Three Dimensional ◽  
Normal Direction ◽  
Curved Surfaces ◽  
Space Craft ◽  
Solar Panels ◽  
Dynamic Surface ◽  
Large Panels ◽  
Dry Adhesion ◽  
Normal And Tangential Loads ◽  
Gripping Force

Most robotic grasping research focuses on objects that are either not large in comparison to the gripper or have small graspable features; however, there are important applications that involve large flat or gently curved surfaces. Examples include robots that grasp the solar panels of space craft, handle large panels in manufacturing, or climb or perch on surfaces. We present a solution for grasping such surfaces consisting of groups of tiles coated with a controllable gecko-inspired adhesive. The tiles are loaded with two sets of tendons: one for distributing the forces evenly while grasping and the other for release. The gripper is passive and can attach and detach with little effort so that it does not disturb either the robot or the object to be grasped. The maximum gripping force in the normal direction can be over 1000 times greater than the required detaching force. The gripper is also fast, allowing a flying quadrotor to attach to a surface milliseconds after the tiles make contact. We present a model of the gripping mechanism and use the model to design the layout of the tiles to best support anticipated normal and tangential loads.

scholarly journals Stretchable micro-scale concentrator photovoltaic module with 15.4% efficiency for three-dimensional curved surfaces

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Daisuke Sato ◽  
Taizo Masuda ◽  
Kenji Araki ◽  
Masafumi Yamaguchi ◽  
Kenichi Okumura ◽  
...  
Keyword(s):  
Concentration Ratio ◽  
Power Conversion ◽  
Three Dimensional ◽  
Thin Film Solar Cells ◽  
Photovoltaic Module ◽  
Silicon Compound ◽  
Curved Surfaces ◽  
Power Sources ◽  
Micro Scale ◽  
Module Design

AbstractStretchable photovoltaics are emerging power sources for collapsible electronics, biomedical devices, and buildings and vehicles with curved surfaces. Development of stretchable photovoltaics are crucial to achieve rapid growth of the future photovoltaic market. However, owing to their rigidity, existing thin-film solar cells based predominantly on silicon, compound semiconductors, and perovskites are difficult to apply to 3D curved surfaces, which are potential real-world candidates. Herein, we present a stretchable micro-scale concentrator photovoltaic module with a geometrical concentration ratio of 3.5×. When perfectly fitted on a 3D curved surface with a sharp curvature, the prototype module achieves an outdoor power conversion efficiency of 15.4% and the daily generated electricity yield improves to a maximum of 190% relative to a non-concentration stretchable photovoltaic module. Thus, this module design enables high areal coverage on 3D curved surfaces, while generating a higher electricity yield in a limited installation area.

Motion Analysis and Simulation of Complex Curved Surface WEDM System

2008 ◽  
Vol 392-394 ◽  
pp. 151-155
Author(s):  
Tong Wang ◽  
K. Jiang ◽  
Shu Qiang Xie ◽  
Shuang Shuang Hao
Keyword(s):  
Electrical Discharge Machining ◽  
Three Dimensional ◽  
Simulation Method ◽  
Curved Surface ◽  
Polar Coordinates ◽  
Curved Surfaces ◽  
Machining Quality ◽  
Motion Parameters ◽  
Dimensional Graph ◽  
Analysis Of Motion

In this paper, the characteristics and general laws of cutting complex curved surface by wire electrical discharge machining (WEDM) system are studied. Based on analysis of motion parameters the universal mathematical model of polar coordinates is derived. Moreover, the simulation of WEDM system is introduced, which is carried out by using language Visual C++ and the three dimensional graph software OpenGL.This simulation method is helpful in improving machining quality and productivity of complex curved surfaces, and is fundation for establishing CAD/CAPP/CAM technology in WEDM.

Spatial Geometric Cells — Quasipolyhedra

2021 ◽  
pp. 30-38
Author(s):  
A. Efremov ◽  
T. Vereschagina ◽  
Nina Kadykova ◽  
Vyacheslav Rustamyan
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Elementary Cell ◽  
Convex Polyhedra ◽  
Curved Surfaces ◽  
Ancient Times ◽  
Graphical Algorithm ◽  
Opening Up ◽  
Hyperbolic Paraboloids ◽  
Three Dimensional Space

Tiling of three-dimensional space is a very interesting and not yet fully explored type of tiling. Tiling by convex polyhedra has been partially investigated, for example, works [1, 15, 20] are devoted to tiling by various tetrahedra, once tiling realized by Platonic, Archimedean and Catalan bodies. The use of tiling begins from ancient times, on the plane with the creation of parquet floors and ornaments, in space - with the construction of houses, but even now new and new areas of applications of tiling are opening up, for example, a recent cycle of work on the use of tiling for packaging information [17]. Until now, tiling in space has been considered almost always by faceted bodies. Bodies bounded by compartments of curved surfaces are poorly considered and by themselves, one can recall the osohedra [14], dihedra, oloids, biconuses, sphericon [21], the Steinmetz figure [22], quasipolyhedra bounded by compartments of hyperbolic paraboloids described in [3] the astroid ellipsoid and hyperbolic tetrahedra, cubes, octahedra mentioned in [6], and tiling bodies with bounded curved surfaces was practically not considered, except for the infinite three-dimensional Schwartz surfaces, but they were also considered as surfaces, not as bodies., although, of course, in each such surface, you can select an elementary cell and fill it with a body, resulting in a geometric cell. With this work, we tried to eliminate this gap and described approaches to identifying geometric cells bounded by compartments of curved surfaces. The concept of tightly packed frameworks is formulated and an approach for their identification are described. A graphical algorithm for identifying polyhedra and quasipolyhedra - geometric cells are described.

Prediction of Residual Stress on Cold-Formed Curvature Plates by Elastoplastic Material Model

2020 ◽  
pp. 1-15
Author(s):  
Yue Lin ◽  
Wei Shen ◽  
Lifei Song ◽  
Enqian Liu
Keyword(s):  
Residual Stress ◽  
Sheet Metal ◽  
Production Efficiency ◽  
Three Dimensional ◽  
Elastoplastic Material ◽  
Curved Surfaces ◽  
Automatic Production ◽  
Cold Forming ◽  
Metal Parts ◽  
Sheet Metal Parts

To meet the demand of automatic production, the multisquare punch forming has been improved to process complex curved plates. However, the improved forming equipment improves the processing quality to the maximum extent, and springback and residual stresses are inevitable phenomena in the cold bending process. Residual stress is an important factor that causes fatigue crack and stress corrosion crack. And the residual stress in machining will seriously affect the fatigue life of cold-pressed parts. Therefore, it is necessary to quantitatively and qualitatively analyze the residual stress caused by the cold forming equipment. Through theoretical derivation and finite element simulation methods, the residual stress distribution for thick plates in the cold forming process was analyzed and compared in this article. Meanwhile, the variation law of residual stress peak with thickness and forming radius was further discussed. The results show that the residual stress distributions obtained by the two theoretical models are in good agreement with the numerical results. The maximum error of peak residual stress is about 10%, which verifies the reliability of theoretical formulas. 1. Introduction A large number of complex curved sheet metal parts are used in aerospace, marine structure, automobile, and other manufacturing industries, which makes the processing and forming of complex curved sheet metal parts attract much attention. In the process of ship construction, the forming and processing of hull plates is an important part of the low intelligence, time-consuming, and serious constraint on shipbuilding automation. Strictly speaking, most of the parts in the hull plate are three-dimensional curved surfaces, most of which are composed of complex undevelopable spatial curved surfaces. It is a very difficult and urgent key technology to process a ship's steel plate into complex three-dimensional curved surface shapes. such as saddle shape or sailed shape (see Fig. 1A), to create a streamlined outer body of the ship. For many years, bending of plates with complex curvatures has been carried out by manual operation, i.e., the combination of heat line forming and rolling bending (see Fig. 1B). However, the production efficiency of the thermoforming process is relatively low, and environmental pollution is relatively serious with bad working conditions and high labor intensity. Moreover, the forming quality depends more on the experience of technicians, and quality cannot be guaranteed. With the increasing demand for automation, the multipoint forming equipment was developed and used for stamping and forming of curved plates.

scholarly journals Computer-Aided Sketching: Incorporating the Locus to Improve the Three-Dimensional Geometric Design

Symmetry ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1181 ◽  
Author(s):  
José Ignacio Rojas-Sola ◽  
David Hernández-Díaz ◽  
Ricardo Villar-Ribera ◽  
Vicente Hernández-Abad ◽  
Francisco Hernández-Abad
Keyword(s):  
Computational Geometry ◽  
Computer Aided Design ◽  
Three Dimensional ◽  
Geometric Design ◽  
Curved Surfaces ◽  
Two Dimensional ◽  
Technical Design ◽  
Computer Aided ◽  
Aided Design

This article presents evidence of the convenience of implementing the geometric places of the plane into commercial computer-aided design (CAD) software as auxiliary tools in the computer-aided sketching process. Additionally, the research considers the possibility of adding several intuitive spatial geometric places to improve the efficiency of the three-dimensional geometric design. For demonstrative purposes, four examples are presented. A two-dimensional figure positioned on the flat face of an object shows the significant improvement over tools currently available in commercial CAD software, both vector and parametric: it is more intuitive and does not require the designer to execute as many operations. Two more complex three-dimensional examples are presented to show how the use of spatial geometric places, implemented as CAD software functions, would be an effective and highly intuitive tool. Using these functions produces auxiliary curved surfaces with points whose notable features are a significant innovation. A final example provided solves a geometric place problem using own software designed for this purpose. The proposal to incorporate geometric places into CAD software would lead to a significant improvement in the field of computational geometry. Consequently, the incorporation of geometric places into CAD software could increase technical-design productivity by eliminating some intermediate operations, such as symmetry, among others, and improving the geometry training of less skilled users.

Function and three-dimensional structure of intervessel pit membranes in angiosperms: a review

IAWA Journal ◽  
2019 ◽  
Vol 40 (4) ◽  
pp. 673-702 ◽  
Author(s):  
Lucian Kaack ◽  
Clemens M. Altaner ◽  
Cora Carmesin ◽  
Ana Diaz ◽  
Mirko Holler ◽  
...  
Keyword(s):  
Water Transport ◽  
Three Dimensional ◽  
Cellulose Microfibrils ◽  
Dimensional Structure ◽  
High Porosity ◽  
Dynamic Surface ◽  
Three Dimensional Structure ◽  
Pit Membrane ◽  
Bordered Pits ◽  
20 Nm

ABSTRACTPit membranes in bordered pits of tracheary elements of angiosperm xylem represent primary cell walls that undergo structural and chemical modifications, not only during cell death but also during and after their role as safety valves for water transport between conduits. Cellulose microfibrils, which are typically grouped in aggregates with a diameter between 20 to 30 nm, make up their main component. While it is clear that pectins and hemicellulose are removed from immature pit membranes during hydrolysis, recent observations of amphiphilic lipids and proteins associated with pit membranes raise important questions about drought-induced embolism formation and spread via air-seeding from gas-filled conduits. Indeed, mechanisms behind air-seeding remain poorly understood, which is due in part to little attention paid to the three-dimensional structure of pit membranes in earlier studies. Based on perfusion experiments and modelling, pore constrictions in fibrous pit membranes are estimated to be well below 50 nm, and typically smaller than 20 nm. Together with the low dynamic surface tensions of amphiphilic lipids at air-water interfaces in pit membranes, 5 to 20 nm pore constrictions are in line with the observed xylem water potentials values that generally induce spread of embolism. Moreover, pit membranes appear to show ideal porous medium properties for sap flow to promote hydraulic efficiency and safety due to their very high porosity (pore volume fraction), with highly interconnected, non-tortuous pore pathways, and the occurrence of multiple pore constrictions within a single pore. This three-dimensional view of pit membranes as mesoporous media may explain the relationship between pit membrane thickness and embolism resistance, but is largely incompatible with earlier, two-dimensional views on air-seeding. It is hypothesised that pit membranes enable water transport under negative pressure by producing stable, surfactant coated nanobubbles while preventing the entry of large bubbles that would cause embolism.

scholarly journals Transparent Object Shape Measurement Based on Deflectometry

Proceedings ◽  
2018 ◽  
Vol 2 (8) ◽  
pp. 548
Author(s):  
Zhichao Hao ◽  
Yuankun Liu
Keyword(s):  
Data Acquisition ◽  
Phase Measurement ◽  
Focal Length ◽  
Three Dimensional ◽  
Normal Direction ◽  
Calibration Data ◽  
Actual Measurement ◽  
Temporal Phase ◽  
Convex Lens ◽  
Normal Orientation

This paper proposes a method for obtaining surface normal orientation and 3-D shape of plano-convex lens using refraction stereo. We show that two viewpoints are sufficient to solve this problem under the condition that the refractive index of the object is known. What we need to know is that (1) an accurate function that maps each pixel to the refraction point caused by the refraction of the object. (2) light is refracted only once. In the simulation, the actual measurement process is simplified: light is refracted only once; and the accurate one-to-one correspondence between incident ray and refractive ray is realized by known object points. The deformed grating caused by refraction point is also constructed in the process of simulation. A plano-convex lens with a focal length of 242.8571 mm is used for stereo data acquisition, normal direction acquisition, and the judgment of normal direction consistency. Finally, restoring the three-dimensional information of the plano-convex lens by computer simulation. Simulation results suggest that our method is feasibility. In the actual experiment, considering the case of light is refracted more than once, combining the calibration data acquisition based on phase measurement, phase-shifting and temporal phase-unwrapping techniques to complete (1) calibrating the corresponding position relationship between the monitor and the camera (2) matching incident ray and refractive ray.

BROADSIDE REFRACTION SHOOTING

Geophysics ◽  
1959 ◽  
Vol 24 (4) ◽  
pp. 725-748 ◽  
Author(s):  
T. C. Richards
Keyword(s):  
Approximate Method ◽  
Three Dimensional ◽  
Field Work ◽  
Significant Error ◽  
Curved Surfaces ◽  
Travel Times ◽  
The Relationship

The three‐dimensional refraction trajectories and travel times in seismic broadside refraction shooting across simple steeply dipping or faulted hypothetical structures are determined when the shotpoint is displaced from the axis. No curved surfaces are assumed and the diffractions to be expected from the structural discontinuities are evaluated. An approximate method for correcting arc time measurements taken over the opposite side to that of the shotpoint is investigated while the conversion of times to dip is discussed. Discussion is also given to the differences in the diffraction time curves caused by changing the shotpoint from the up to the down side of a fault and the relationship these curves have with the refraction time curves in both arc and broadside shooting. The results of these studies indicate the care that should be taken in distinguishing between refracted and diffracted events, and in relating a measured broadside time to a particular point on the refractor. The latter may lead to significant error when simple mid‐point depth computations, often resorted to in field work, are employed.

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