Search results for "geometric modeling"
showing 10 items of 19 documents
A new approach to simulate coating thickness in cold spray
2020
Abstract In the process of cold spray on complex components, the coating thickness is an important indicator to monitor and control. Current methods such as destructive tests or direct mechanical measurements can only be performed after spraying. Besides, these methods lead to production shutdown and additional costs . This article presents a novel approach predicting coating thickness for components with complex curved surfaces, especially in the case of shadow effects. Firstly, a three-dimensional geometric model of the coating profile based on Gaussian distribution was developed. In addition, the relative deposition efficiency (RDE) resulting from the different robot kinematic parameters…
An associative link from geometric to symbolic representations in artificial vision
1991
Recent approaches to modelling the reference of internal symbolic representations of intelligent systems suggest to consider a computational level of a subsymbolic kind. In this paper the integration between symbolic and subsymbolic processing is approached in the framework of the research work currently carried on by the authors in the field of artificial vision. An associative mapping mechanism is defined in order to relate the constructs of the symbolic representation to a geometric model of the observed scene.
Conversion d'un carreau de Bézier rationnel biquadratique en un carreau de cyclide de Dupin quartique
2006
Dupin cyclides were introduced in 1822 by the French mathematician C-P. Dupin. They are algebraic surfaces of degree 3 or 4. The set of geometric properties of these surfaces has encouraged an increasing interest in using them for geometric modeling. A couple of algorithmes is already developed to convert a Dupin cyclide patch into a rational biquadratic Bezier patch. In this paper, we consider the inverse problem: we investigate the conditions of convertibility of a Bezier patch into a Dupin cyclide one, and we present a conversion algorithm to compute the parameters of a Dupin cyclide with the boundary of the patch that corresponds to the given Bezier patch.
Computation of Yvon-Villarceau circles on Dupin cyclides and construction of circular edge right triangles on tori and Dupin cyclides
2014
Ring Dupin cyclides are non-spherical algebraic surfaces of degree four that can be defined as the image by inversion of a ring torus. They are interesting in geometric modeling because: (1) they have several families of circles embedded on them: parallel, meridian, and Yvon-Villarceau circles, and (2) they are characterized by one parametric equation and two equivalent implicit ones, allowing for better flexibility and easiness of use by adopting one representation or the other, according to the best suitability for a particular application. These facts motivate the construction of circular edge triangles lying on Dupin cyclides and exhibiting the aforementioned properties. Our first contr…
New Geometric Constraint Solving Formulation: Application to the 3D Pentahedron
2014
Geometric Constraint Solving Problems (GCSP) are nowadays routinely investigated in geometric modeling. The 3D Pentahedron problem is a GCSP defined by the lengths of its edges and the planarity of its quadrilateral faces, yielding to an under-constrained system of twelve equations in eighteen unknowns. In this work, we focus on solving the 3D Pentahedron problem in a more robust and efficient way, through a new formulation that reduces the underlying algebraic formulation to a well-constrained system of three equations in three unknowns, and avoids at the same time the use of placement rules that resolve the under-constrained original formulation. We show that geometric constraints can be …
Solution isolation strategies for the Bernstein polytopes-based solver
2013
The Bernstein polytopes-based solver is a new method developed to solve systems of nonlinear equations, which often occur in Geometric Constraint Solving Problems. The principle of this solver is to linearize nonlinear monomials and then to solve the resulting linear programming problems, through linear programming. However, without any strategy for the isolation of the many solutions of multiple-solution systems, this solver is slow in practice. To overcome this problem, we propose in this work, a study of several strategies for solution isolation, through the split of solution boxes into several subboxes, according to three main steps answering the questions: when, where, and how to perfo…
Building 3D Geometric and Kinematic Models of Five-Axis Machine-Tools for Manufacturing Prosthetic Devices
2015
The paper presents the process of building and testing a geometric and kinematic model of a five-axis machining center, which can be used for accurate cutting processes simulation of complex parts. After building the model, it was be tested by simulating the machining process of a hip joint prosthetic device. The prosthetic device was chosen because of its complex shape and because it was obtained by a 3D scanning process, which means that the part was reconstructed using meshes, instead of surfaces, which makes the toolpath control more difficult.
Modeling and simulation of a VCM micromotor and its potential applications
2013
This paper presents the modeling and simulation of a VCM electrostatic micromotor with a new FEM analysis and implementation method, in order to determine the electrical parameters of the model and the generated electrostatic torque. Both the modeling and the simulation have been achieved using several software programs. In particular, the geometric model created with AUTOCAD has been imported to the FEMM program for the finite-element-method analysis. Then, with the LUA and MATLAB simulation programs, the parameters of the model and the related electrostatic torque have been calculated. The results obtained from this work have been compared with those reported in other scientific papers, s…
REDUCTION OF CONSTRAINT SYSTEMS
1993
Geometric modeling by constraints leads to large systems of algebraic equations. This paper studies bipartite graphs underlaid by systems of equations. It shows how these graphs make possible to polynomially decompose these systems into well constrained, over-, and underconstrained subsystems. This paper also gives an efficient method to decompose well constrained systems into irreducible ones. These decompositions greatly speed up the resolution in case of reducible systems. They also allow debugging systems of constraints.
Assembly and Speed in Ion-Exchange-Based Modular Phoretic Microswimmers.
2017
We report an experimental study on ion-exchange-based modular microswimmers in low-salt water. Cationic ion-exchange particles and passive cargo particles assemble into self-propelling complexes, showing self-propulsion at speeds of several micrometers per second over extended distances and times. We quantify the assembly and speed of the complexes for different combinations of ion-exchange particles and cargo particles, substrate types, salt types and concentrations, and cell geometries. Irrespective of the experimental boundary conditions, we observe a regular development of the assembly shape with increasing number of cargo. Moreover, the swimming speed increases stepwise upon increasing…