In robot planning problems, the complete coverage path planning refers to the problem of determining a path that a robot must take in order to pass over each point in an environment and avoid obstacles. Applications i...
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ISBN:
(纸本)9781424402588
In robot planning problems, the complete coverage path planning refers to the problem of determining a path that a robot must take in order to pass over each point in an environment and avoid obstacles. Applications include demining, sweeping, cleaning, vacuuming, inspection robots. For this kind of problem, not only the complete coverage should be performed, but an efficient path is highly desired. Using traditional sweeping line strategy often requires several relocation moves, leading to poor efficiency. In this paper we describe a geometric algorithm for generating paths by using a modified sweeping line strategy that attempts to minimize extra relocation moves. Several examples are used in the paper to show the advantage of our algorithm over traditional approaches.
For digitizations a grid is given, usually it is considered as Z2. The digital image of a real object depends on the respective position of the object and the grid. In this paper we consider the simplest objects of th...
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One of the most effective methods for reducing milling exit burrs is to prevent the tool from exiting the workpiece. Exit here refers the condition in which a cutting edge is moving out of the workpiece while removing...
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One of the most effective methods for reducing milling exit burrs is to prevent the tool from exiting the workpiece. Exit here refers the condition in which a cutting edge is moving out of the workpiece while removing material. Only entrance burrs can occur under this circumstance, which are usually considered burr-free. This study proposes a set of geometric algorithms for avoiding tool exits in planar milling. Two distinct approaches are developed for tool path planning of 2-D polygons. The first approach generates exit-free tool paths by offsetting the workpiece edges with appropriate widths of cut. The second one adjusts tool positions locally on given tool paths. In addition, a two-stage algorithm is designed for 2-D free-form contours. The cutter locations causing the tool to exit the workpiece are first detected;then a heuristic scheme is applied to generate new cutter locations with no tool exits. Experimental results show that edge quality is significantly improved using the proposed methods. This work provides a feasible way for suppressing burr formation in an automatic manner, and thus reduces the need for deburring.
We propose an efficient and exact method for the adaptive sign detection of 4x4 determinants using a standard arithmetic unit. The entities of determinants are variable length integers (integers of arbitrary bit lengt...
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We propose an efficient and exact method for the adaptive sign detection of 4x4 determinants using a standard arithmetic unit. The entities of determinants are variable length integers (integers of arbitrary bit length). The integers are expressed in 16-bit data units, and the sign detection is reduced to the computation of 4x4 determinants of 16-bit integers. To accelerate the computation, the calculation is performed by using a standard arithmetic unit. We have implemented our method and confirmed that it significantly improves the computation time of 4x4 determinants. The method can be applicable to many geometric algorithms that need the exact sign evaluation of 4x4 determinants, especially to construct robust geometric algorithms.
The nofit polygon is a powerful and effective tool for handling the geometry required for a range of solution approaches to two-dimensional irregular cutting-stock problems. However, unless all the pieces are convex, ...
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The nofit polygon is a powerful and effective tool for handling the geometry required for a range of solution approaches to two-dimensional irregular cutting-stock problems. However, unless all the pieces are convex, it is widely perceived as being difficult to implement, and its use has therefore been somewhat limited, The primary purpose of this paper is to correct this misconception by introducing a new method of calculating the nofit polygon. Although it is based on previous approaches which use the mathematical concept of Minkowski sums, this new method can be stated as a set of simple rules that can be implemented without an indepth understanding of the underlying mathematics. The result is an approach that is both very general and easy to use. Scope and purpose Cutting and packing problems involving irregular shapes are common in industries ranging from clothing and footware to engineering and shipbuilding. An important feature of any automated solution technique for such problems is the way in which the geometric calculations are handled. One of the most efficient approaches is to pre-process many of the calculations using a concept known as the nofit polygon (NFP). However, use of the NFP has been limited due to the difficulty in its calculation for arbitrary irregular pieces, This paper outlines the concept of the NFP in the context of the irregular cutting-stock problem and introduces a new simplified approach to its calculation. The aim is to make this powerful concept more easily accessible to those involved in the cutting and packing of irregular shapes, (C) 2000 Elsevier Science Ltd. All rights reserved.
Linking number is a basic invariant of a closed curve in topology. In this paper, linking number is generalized in a computational way to reflect the spatial relationship between a point and a line segment, an are, a ...
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Linking number is a basic invariant of a closed curve in topology. In this paper, linking number is generalized in a computational way to reflect the spatial relationship between a point and a line segment, an are, a plane subdivision, a three-dimensional shape, a three-dimensional object and a three-dimensional space subdivision. An algebraic algorithm for the point-in-polygon test is devised on the base of the generalized linking number. The algorithm is characterized by the algebraic property that the linking number of a point to a polygon is merely the arithmetic sum of the linking numbers of the point to all the line segments of the polygon. The algorithm takes intersection into consideration, but no intersection is actually computed. It calculates the linking number, but no trigonometric function is processed. Detailed time complexity analysis shows that this algorithm greatly improves currently existing algorithms for the point-in-polygon test. Another achievement of this paper is the consistent and successful extension of the algebraic algorithm for the point-in-polygon test to point inclusion queries in two-dimensional objects, plane subdivisions, three-dimensional shapes, three-dimensional objects and three-dimensional space subdivisions. All these algorithms retain the algebraic character. (C) 2000 Elsevier Science Ltd. All rights reserved.
We propose a novel algorithm far the independent component analysis that reshapes a scatter diagram or the joint probability density function of the pixel values of the mixed signals. The detailed procedure of the alg...
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ISBN:
(纸本)0819432148
We propose a novel algorithm far the independent component analysis that reshapes a scatter diagram or the joint probability density function of the pixel values of the mixed signals. The detailed procedure of the algorithm is described and its performance is numerically evaluated. The present algorithmgeometrically separates original independent images from mixed images by the linear transformation, in which shift, shearing and rotation are performed to the scatter diagram. After the transformations and normalizations, the basis vectors of the independent signal become orthogonal and match the coordinates. In the implementation, it is shown that the algorithm can decompose two independent images from two mixed images. In additions, the proposed algorithm are compared to two conventional algorithms;[G. Burel: Neural Networks 5, 937 (1992)] and [A. Hyvarinen and E. Oja: Neural Comp. 9, 1483 (1997)], in calculation speed and extraction accuracy.
The paper deals with the modelling of unknown objects and location determination of known ones. The operator models objects using data issued from the video image and a time of flight infra red range finder. We presen...
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The paper deals with the modelling of unknown objects and location determination of known ones. The operator models objects using data issued from the video image and a time of flight infra red range finder. We present methods to build an embodying volume for unknown objects. These methods are available for polyhedral and conical objects, which represent the basis of most industrial environments. The location determination of known objects is determined using 2D clues obtained through video image. A two-step algorithm is implemented and assessed. The first step is available in case of object large motion, it is a geometric algorithm, which doesn't use redundant data;it provides a first estimate of the pose. The second step is available in case of object small motion. A linear approach is carried out to determine the pose. It allows the use of redundant data, so it improves the accuracy achieved after the first step.
作者：
DYER, METeesside Polytechnic
Dep of Mathematics & Statistics Middlesbrough Engl Teesside Polytechnic Dep of Mathematics & Statistics Middlesbrough Engl
$O(n)$ time algorithms for linear programming problems with two or three variables and n constraints are described. The approach uses convexity, dominance of linear functions and linear-time median finding algorithms....
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$O(n)$ time algorithms for linear programming problems with two or three variables and n constraints are described. The approach uses convexity, dominance of linear functions and linear-time median finding algorithms. The algorithms improve the previously known best bounds of $O(n\log n)$ time for both of these problems.
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