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Consecutive scanning scheme: applications to localization and navigation for mobile robots in a dynamic environment
Abstract
This thesis presents a mobile robot localization and obstacle detection algorithm based on consecutive range sensor scans. For a known environment, a mobile robot may scan the environment using a range sensor which can rotate 360o. The mobile robot stops during the scanning, and it moves a small distance between scans. By moving only a small distance, systematic errors in dead reckoning of relative position are ignored. The robot scans the environment once again. The edges of the environment will be determined from the range sensor data. Then, deducing intersections of observed edges, the knowledge of environment allows localization. Furthermore, the consecutive scanning data set provides obstacle information in unknown environment. When obstacles are in the environment, the range data contains information about robot position through the environment module and obstacle position. By comparing two data sets, the movement of an obstacle can be extracted. By using information from consecutive scans of the sensor, coupled with robot kinematics, correlations of the range data can improve robot localization and detection of moving obstacles as compared to a single scan. The algorithm is presented with both simulation and experimental results. With 2 scans, the velocity and movement direction of the moving obstacle can be approximated. The possibility of collision between the two moving objects can be determined from the predefined robot path and estimated obstacle path. As the robot travels, the uncertainty region grows because of the systematic errors. For the obstacle, uncertainty region grows because of the approximation error. If the error sources follow Gaussian distribution, the uncertainty regions are shown as ellipse shape. By tracking both paths of two moving objects and corresponding error ellipses, the collision possibility is calculated on the basis of probability distribution. The probability distribution of the common area between these two ellipses is regarded as the possibility as the collision. The collision predictor decides whether to make change on the robot path or not. Once there is a collision warning from the collision predictor, path replanner regenerates the mobile robot path to avoid the possible collision.
Description
Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references (leaves 49-52).
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Citation
Lee, Jae Yong (2002). Consecutive scanning scheme: applications to localization and navigation for mobile robots in a dynamic environment. Master's thesis, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /ETD -TAMU -2002 -THESIS -L445.
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