Sistem ve Kontrol Mühendisliği
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Browsing Sistem ve Kontrol Mühendisliği by Subject "Autonomous robots."
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Item Design and simulation of a multi-agent autonomous robot system for industrial facilities(Thesis (M.S.)-Bogazici University. Institute for Graduate Studies in Science and Engineering, 2006., 2006.) Özkan, Sarp Baran.; Akın, H. Levent.In this study we aim to observe the usage of multi-agent autonomous robots in industrial facilities and the related alternative application details of this usage. The purpose of the utilization of multi-agent autonomous robots in manufacturing plants is to pass over the bottlenecks existing in the usage of Automated Guided Vehicle (AGV) systems, which are being used in transportation of materials in such systems. Multi-agent autonomous robots are a current research issue in the field of robotics. Unlike AGV systems, determining their routes without using fixed transmitters, autonomous robots will be able to move liberally between loading and unloading points. Mobility in manufacturing environment very frequently causes the blockage of the route of AGV systems or gives way to the impossibility of using such environment for other activities. In case of interruption of paths by fixed obstacles or dynamic obstacles described as workers, robots will be able to continue towards their targeted destination either by maneuvers of avoidance or by determining a new route. Consequently this situation will provide a new facility for a more flexible manufacturing. For modeling the environment in our study, we have applied Webots, a 3-D simulation program that, both with its graphical interface and its C, C++ and Java programming units, is used to create a test environment for the applications of units, various production environment layouts, robotic elements trials, robot architecture and different path planning and task assignment strategies. In our studies, robots and production environment have been modeled and programmed. Conclusions of simulations have all been evaluated to measure the proposed system’s responsiveness to flexible manufacturing. The files and instructions necessary to run the simulation program are available in the appendix CD which is attached inside the back cover of the thesis. Information related to the content and usage of the appendix CD is in the Read.Me text file.Item Developing a probabilistic post perception module for mobile robotics(Thesis (M.S.)-Bogazici University. Institute for Graduate Studies in Science and Engineering, 2009., 2009.) Kavaklıoğlu, Can.; Akın, H. Levent.All autonomous robots need to gather information about their surroundings. Once information about the environment is accurately extracted a great deal of further research is possible ranging from human computer interaction to high level action planning. However experience indicates achieving accurate perception can be a challenging problem. One of the problems is erroneous perception of the unrelated features of the environment as landmarks. Due to imperfect nature of sensors, methods should be developed to compensate for the uncertainties introduced by the low level perception algorithms. Looking from this point of view, the self localization literature may be seen as an effort to resolve the uncertainties introduced by lower level perception algorithms. This thesis proposes an algorithm to work between low level visual detection algorithms and higher level modules of a robot. The algorithm aims to select and remove erroneous perception information generated due to misplaced landmarks. Defining landmarks and correct locations for landmarks might sound very environment dependent at first. However this is not the case due to the generic de nition of a landmark and correct location. Using the meta pose instead of a specific pose as the state space, the method becomes easily portable with a few alterations in the parameters of the underlying probabilistic framework. Experiments are performed in two different environments to show general nature of the proposed algorithm.Item Development of a multi-sensored autonomous ground vehicle(Thesis (M.S.)-Bogazici University. Institute for Graduate Studies in Science and Engineering, 2009., 2009.) Daniş, Fahri Serhan.; Akın, H. Levent.In this study, we investigated the problem of constructing a small sized driveby- wire ground vehicle with sensors and the problem of its autonomous navigation in unstructured outdoor environments. Although different sensor installations were tried on the vehicle, the focus was on the camera that would imitate the human perception using monocular cues in the acquired images. A high importance was given to a depth perception algorithm that is used to estimate the relative maximum distances of the obstacles around. A study on the importance of the features extracted from the images was also included so that the running time of the algoritm could be decreased, which would enable the system run in real world. We have seen that lesser number of features could well be used to estimate the depths in an image. The experiments were done on a rough terrain with trees and bushes around where the robot also had to cope with the physical conditions while trying to find the best direction to follow. The results were encouraging; the vehicle travelled longer distances; and even traversed the whole test area as the used methods got more developed, however, when the system is considered as a whole, we made an inference that more feasible models are required to compensate for erroneous estimations and, in the end, to make the navigation safer, since the final decision of the vehicle depends on many sequential parameters.Item Development of a vacuum cleaner mobile robot(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1998., 1998.) Sardağ, Alp.; Akın, H. Levent.This study presents the results of the development of an autonomous mobile robot which is a domestic autonomous vacuum cleaner. The robot is designed according to some new concepts established in this field during the last decade. These principles are artificial life, subsumption architecture and other bottom-up methodologies. These ideas have been applied to the complete robot design, spanning from the shape of the robot to the sensors, from the electronics to the software control structure. We have built the robot and programmed it to perform various reactive behaviours. The autonomous vacuum cleaner performs area coverage in a room by combining distinct behaviors. The robot has 11 sensors which are used in the algorithms examined. The robot behaviors allow it to avoid obstacles, follow walls, break out of confined areas, detect floor and find a docking area. The performance tests are done through a dedicated simulator and by observation. The experiments performed here were both in the simulator and real-time it appears that the best area coverage algorithm among those tried consisted of a random walk with a probability of 0.10 for following a wall after each encounter with an obstacle.Item Implementation of continuous POMDP algorithms on autonomous robots(Thesis (M.S.)-Bogazici University. Institute for Graduate Studies in Science and Engineering, 2008., 2008.) Sezen, Derya.; Akın, H. Levent.Uncertainty is a fundamental problem for autonomous agents in a partially observable real world, where the sensors are not able to give the complete state of the environment. Although the outcomes of actions are not predictable, the agents must behave rationally. Furthermore, continuous nature of the environment makes the problem more difficult to model. Markov Decision Process (MDP) is a way to model this kind of problems. Partially observable Markov decision process (POMDP) is an extension of MDP which can be used in environments which are not fully observable. In order to model the real world, the continuous states must be converted to discrete states. The aim of this work is to model the real world environment and implement ARKAQ learning algorithm which is suitable for Partially observable Markov decision problems (POMDPs). The experiments are realized with Sony AIBO four-legged robotic pets under Webots simulation environment. Two problems are studied: ``Ball Approaching'' and ``Scoring Goal''. The predefined targets are achieved by the robots and the results in goal scoring show that ARKAQ is clearly much more successful compared to random actions. The optimality of the results are discussed and the parameters that affect the optimality are explained.