3145025
Quantitative Evaluation of the Exploration Strategies of a Mobile Robot
This article describes an experimental investigation into the map-building and exploration capabilities of a mobile robot. Two types of map are used: a set of line and point features, and a grid-based free-space map. Potential features are ex tracted from sonar range readings and classed as "confirmed" if detected repeatedly. The free-space map is derived from the set of confirmed features. A distance-transform algorithm is then used to plan paths on this map. The confirmed features are used by a Kalman filter to estimate the robot's position relative to known objects. This research places exceptional stress on the need for practical experimentation and quantitative, statistical evaluation of the results. For this to be possible, it is essential to have a clearly defined measure of map quality. A novel metric is defined that predicts the effectiveness of the robot if it were to use the map to execute a set of test tasks. Exploration strategies are tested experimentally in a range of environments and starting positions. The results are eval uated and compared statistically. The tested strategies range from those that are totally reactive, such as wall-following, to those that use the developing map to focus attention on the un examined parts of the environment. The most promising results are observed from hybrid exploration strategies that combine the robustness of reactive navigation and the directive power of map-based strategies.
42038608
A low-cost system using sparse vision for navigation in the urban environment
Abstract Established mobility aids, such as the long cane, enable visually impaired users to travel safely in urban environments. This paper describes continuing work to enhance this mobility by providing a series of high-level navigational goals. In particular, we describe algorithms to detect doorways and to facilitate centre-path travel. To maintain high performance at low cost, both algorithms use sparsely-sampled images from a single camera. Doorway detection is achieved by the detection of characteristic patterns of near-vertical and near-horizontal lines. The direction of travel along a path is determined by locating the dominant vanishing point of the lines in the image. Experimental results are presented for both algorithms.
12480757
Robotic sensing for the partially sighted
Partial sightedness is a sensory disability which can to some extent be alleviated by artificial aids. Many of the sensory methods used in robotics can be applied in attempts to recapture some of the sensory information a partially sighted person has lost. This paper describes a device which uses sonar and stereo vision sensors for this task. The device is portable, and is worn by the user, giving them freedom of movement over kerbs, stairs and rough ground. Sensor motion during walking is measured using visual egomotion recovery and odometry, and has been modelled to allow compensation in the sensor readings. A ground position estimate is continually updated by scene ground-plane fitting, or from the walk-motion model, and is used to classify scene features as obstacles or parts of the ground. Methods for the robust reconstruction of image points and lines into scene features are developed. The recognition of world objects of exceptional significance to a mobile person - kerbs and stairs - is given particular attention. A user interface, which has undergone limited real world testing, is also described. Experimental results are presented for the various parts of the system.
16301640
A stereo vision-based aid for the visually impaired
This paper describes a portable vision-based obstacle detection system, intended for use by blind people. The system combines an obstacle detection system designed for AGVs with recalibration of ground position and a Kalman Filter based model of the person's walking movement. The system uses stereo vision. Obstacle detection is achieved through comparison of the disparity seen with that expected from the position of the ground. Recalibration of ground position is made by plane fitting in the ground region. Motion estimation using two visual methods and the use of an inclinometer is described. The results show satisfactory success in all parts of the system.
7421438
A reliable position estimation method of the service robot by map matching
In this paper, a reliable position estimation method of the indoor service robot is proposed. The service robot PSR1 is a wheeled mobile manipulator which navigates in office buildings. Our localization method is a map-matching scheme using scanned range data, without using any artificial landmark. The proposed algorithm can provide solutions for both a global localization problem and a local position tracking. A probabilistic position estimation scheme is designed based on MCL (Monte Carlo localization). Two measure functions are developed for computing positional probabilities. The robot automatically decides whether it uses geometric pattern matching (i.e. walls, pillars) by Hough transform. The proposed scheme shows reliable performance in both polygonal environments and non-polygonal environments even there exist many obstacles. Experimental results demonstrate the validity and feasibility of the proposed localization algorithm for the service robot to navigate in an office building, using the natural environmental characteristics.
445935
The TIGR rice genome annotation resource: annotating the rice genome and creating resources for plant biologists
Rice is not only a major food staple for the world's population but it also is a model species for a major group of flowering plants, the monocotyledonous plants. Draft genomic sequence of two subspecies of rice, Oryza sativa spp. japonica and indica ssp. are publicly available. To provide the community with a resource to data-mine the rice genome, we have constructed an annotation resource for rice (http://www.tigr.org/tdb/e2k1/osa1/). In this resource, we have annotated the rice genome for gene content, identified motifs/domains within the predicted genes, constructed a rice repeat database, identified related sequences in other plant species, and identified syntenic sequences between rice and maize. All of the data is available through web-based interfaces, FTP downloads, and a Distributed Annotation System.
17062756
Toward alternative measures for ranking venues: a case of database research community
Ranking of publication venues is often closely related with important issues such as evaluating the contributions of individual scholars/research groups, or subscription decision making. The development of large-scale digital libraries and the availability of various meta data provide the possibility of building new measures more efficiently and accurately. In this work, we propose two novel measures for ranking the impacts of academic venues an easy-to-implement seed-based measure that does not use citation analysis, and a realistic browsing-based measure that takes an article reader's behavior into account. Both measures are computationally efficient yet mimic the results of the widely accepted Impact Factor. In particular, our proposal exploits the fact that: (1)in most disciplines, there are "top" venues that most people agree on; and (2) articles that appeared in good venues are more likely to be viewed by readers. Our proposed measures are extensively evaluated on a test case of the Database research community using two real bibliography data sets - ACM and DBLP. Finally, ranks of venues by our proposed measures are compared against the Impact Factor using the Spearman's rank correlation coefficient, and their positive rank order relationship is proved with a statistical significance test.
36921568
A Study on Key Distribution and ID Registration in the AAA System for Ubiquitous Multimedia Environments
Media environment has been rapidly changed these days. Internet provides multimedia environment and has become a part of our everyday life as a new advertisement media. Authentication methods typically involve an authentication server in the home network from the authentication server of the external network, and then the external network is notified with the authentication result in the home authentication server. This paper discusses and proposes a key distribution protocol that ca be used when the user moves the external network and to ensure secure communication with the external authentication server. As the proposed technology does not receive the reissue of authentication from the home authentication server in case moving between the external authentications servers, authentication server overload can be reduced and the home network can be made to issue the key using the registered password.
36612071
SPY-TEC: An efficient indexing method for similarity search in high-dimensional data spaces
Most of all index structures based on the R-tree have failed to support eAcient indexing mechanisms for similarity search in high-dimensional data spaces. This is due to the fact that most of the index structures commonly use balanced split strategy in order to guarantee storage utilization and the shape of queries for similarity search is a hypersphere in high-dimensional spaces. In this paper, we propose the Spherical Pyramid-Technique (SPY-TEC), an eAcient indexing method for similarity search in high-dimensional data space. The SPY-TEC is based on a special partitioning strategy, which is to divide the d-dimensional data space first into 2d spherical pyramids, and then cut the single spherical pyramid into several spherical slices. This partition provides a transformation of d-dimensional space into one-dimensional space as the Pyramid-Technique [14] does. Thus, we are able to use a B a -tree to manage the transformed one-dimensional data. We also propose the algorithms to process hyperspherical range queries on the data space partitioned by this partitioning strategy. Finally, we show that the SPY-TEC clearly outperforms other related techniques including the Pyramid-Technique in processing hyperspherical range queries through various experiments using synthetic and real data. ” 2000 Elsevier Science B.V. All rights reserved.