Göktürk Üçoluk

To Afford or Not to Afford: A New Formalization of Affordances Toward Affordance-Based Robot Control

The concept of affordances was introduced by J. J. Gibson to eXplain how inherent “values” and “meanings” of things in the environment can be directly perceived and how this information can be linked to the action possibilities offered to the organism by the environment. Although introduced in psychology, the concept influenced studies in other fields ranging from human—computer interaction to autonomous robotics. In this article, we first introduce the concept of affordances as conceived by J. J. Gibson and review the use of the term in different fields, with particular emphasis on its use in autonomous robotics. Then, we summarize four of the major formalization proposals for the affordance term. We point out that there are three, not one, perspectives from which to view affordances and that much of the confusion regarding discussions on the concept has arisen from this. We propose a new formalism for affordances and discuss its implications for autonomous robot control. We report preliminary results obtained with robots and link them with these implications.

Automatic reconstruction of broken 3-D surface objects

Abstract The problem of reconstruction of broken surface objects embedded in 3-D space is handled. A coordinate independent representation for the crack curves is developed. A new robust matching algorithm is proposed which serves for finding matching pieces even when some brittle pieces are missing. A prototype system having an X-based GUI has been developed. This system generates artifical wire–frame data of broken pieces (with some noise) for a pot-shaped 3-D object and then recombines it using the proposed algorithms.

Genetic Algorithm Solution of the TSP Avoiding Special Crossover and Mutation

Abstract Ordinary representations of permutations in Genetic Algorithms (GA) is handicapped with producing offspring which aze not permutations at all. The conventional solution for crossover and mutation operations of permutations is to device ‘special’ operators. Unfortunately these operators suffer from violating the nature of crossover. Namely, considering the gene positions on the chromosome, these methods do not allow n-point crossover techniques which are known to favour building-block formations. In this work, an inversion sequence is proposed as the representation of a permutation. This sequence allows repetitive values and hence is robust under ordinary (n-point) crossover. There is a one-to-one mapping from ordinary permutation representation to the inversion sequence representation. The proposed method is used for solving TSPs and is compared to the well known PMX special crossover method. It is observed that this method outperforms PMX in convergence rate by a factor which can be as high as 1...

A genetic algorithm approach for verification of the syllable-based text compression technique

Provided that an easy mechanism exists for it, it is possible to decompose a text into strings that have lengths greater than one and occur frequently. Having in one hand the set of such frequently occurring strings and in the other the set of letters and symbols, it is possible to compress the text using Huffman coding over an alphabet which is a subset of the union of these two sets. Observations reveal that, in most cases, the maximal inclusion of the strings leads to an optimal length of compressed text. However, the verification of this prediction requires the consideration of all subsets in order to find the one that leads to the best compression. A genetic algorithm is devised and used for this search process. In Turkish texts, because of the agglutinative nature of the language, a highly regular syllable formation provides a useful testbed.

Kaluza-Klein reduction of generalised theories of gravity and nonminimal gauge couplings

The Kaluza-Klein reduction of a generalised theory of gravity in D=5 dimensions is given. The form of the interactions among the gravitational, electromagnetic and massless scalar fields in four dimensional spacetime is exhibited.

A controlled genetic programming approach for the deceptive domain

Traditional genetic programming (GP) randomly combines subtrees by applying crossover. There is a growing interest in methods that can control such recombination operations in order to achieve faster convergence. In this paper, a new approach is presented for guiding the recombination process for genetic programming. The method is based on extracting the global information of the promising solutions that appear during the genetic search. The aim is to use this information to control the crossover operation afterwards. A separate control module is used to process the collected information. This module guides the search process by sending feedback to the genetic engine about the consequences of possible recombination alternatives.

Vision-Based Detection and Distance Estimation of Micro Unmanned Aerial Vehicles

Detection and distance estimation of micro unmanned aerial vehicles (mUAVs) is crucial for (i) the detection of intruder mUAVs in protected environments; (ii) sense and avoid purposes on mUAVs or on other aerial vehicles and (iii) multi-mUAV control scenarios, such as environmental monitoring, surveillance and exploration. In this article, we evaluate vision algorithms as alternatives for detection and distance estimation of mUAVs, since other sensing modalities entail certain limitations on the environment or on the distance. For this purpose, we test Haar-like features, histogram of gradients (HOG) and local binary patterns (LBP) using cascades of boosted classifiers. Cascaded boosted classifiers allow fast processing by performing detection tests at multiple stages, where only candidates passing earlier simple stages are processed at the preceding more complex stages. We also integrate a distance estimation method with our system utilizing geometric cues with support vector regressors. We evaluated each method on indoor and outdoor videos that are collected in a systematic way and also on videos having motion blur. Our experiments show that, using boosted cascaded classifiers with LBP, near real-time detection and distance estimation of mUAVs are possible in about 60 ms indoors (1032×778 resolution) and 150 ms outdoors (1280×720 resolution) per frame, with a detection rate of 0.96 F-score. However, the cascaded classifiers using Haar-like features lead to better distance estimation since they can position the bounding boxes on mUAVs more accurately. On the other hand, our time analysis yields that the cascaded classifiers using HOG train and run faster than the other algorithms.

Introduction to Programming Concepts with Case Studies in Python

The current text provides a clear introduction to Computer Science concepts in a programming environment. It is designed as suitable use in freshman- or introductory level coursework in CS and provides the fundamental concepts as well as abstract theorems for solving computational problems. The Python language serves as a medium for illustrating and demonstrating the concepts.

Design and Usage of a New Benchmark Problem for Genetic Programming

Not so many benchmark problems have been proposed in the area of Genetic Programming (GP). In this study, a new artificial benchmark problem is designed for GP. The different parameters that can be used to tune the difficulty of the problem are analyzed. Also, the initial experimental results obtained on different instances of the problem are presented.

Direct-curvature Yang-Mills field couplings induced by the Kaluza-Klein reduction of Euler form actions in seven dimensions

The Kaluza-Klein reduction of Euler form actions on M4*S3 is considered. Direct-curvature Yang-Mills field coupling terms in the reduced action of the generic types RF2 and RF3 are explicitly given.