Some quite precise teleoperated navigation of a simple radio controlled robotic vehicle can be achieved by providing colour video camera based stereo vision feedback to the remote operator. With a little practice the ...
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Some quite precise teleoperated navigation of a simple radio controlled robotic vehicle can be achieved by providing colour video camera based stereo vision feedback to the remote operator. With a little practice the operator is able to experience a degree of telepresence sufficient to render the navigation task natural and safe. This paper details the components of the systems and describes its use for teleoperated lawn mowing of a typical domestic backyard. This development is to be regarded as an intermediate stage between direct human control and fully autonomous operation, between which modes it is intended that the operator withdraw gracefully from the task at hand.< >
Texture is an important preattentive cue in region-based segmentation of images. In this paper, we discuss the use of circular-Mellin features for segmenting an image into homogenous regions. The circular-Mellin opera...
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Texture is an important preattentive cue in region-based segmentation of images. In this paper, we discuss the use of circular-Mellin features for segmenting an image into homogenous regions. The circular-Mellin operators represent the spectral decomposition of the image scene in the polar-log coordinate system and are invariant to both scale and orientation of the target. Coupled with the unique shift invariance property of the correlator architecture, these circular-Mellin operators can be used for rotation- and scale-invariant feature extraction. We note that while both these feature extractors have similar functional form to the Gabor functions, the distortion-invariant characteristics of the circular-Mellin operators make them preferable for texture segmentation. Segmentation results to demonstrate their salient properties are presented.< >
A binocular robot head, BETH, with ten degrees of freedom (DOF) has been developed for research in active vision. To complement BETH, a graphical simulation and visualization environment has also been developed. The o...
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A binocular robot head, BETH, with ten degrees of freedom (DOF) has been developed for research in active vision. To complement BETH, a graphical simulation and visualization environment has also been developed. The objective of building the graphical system is to create a comprehensive design tool to design and study the dynamic behavior of sensory-motor systems and their interactions with the environment. This environment integrates perception and motor actions and features complete kinematic simulation of BETH, it's sensors and it's workspace. We demonstrate the utility of this environment in systematic and extensive experimental development of computational frameworks and algorithms for 3D active vision systems which utilizes multiple passive depth cues (stereo, vergence, and depth from focusing).< >
This paper describes one aspect of a project whose goal is to move a robot in an unknown environment and find pipes to decommission. While moving through the environment a low level map, in the form of an occupancy gr...
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This paper describes one aspect of a project whose goal is to move a robot in an unknown environment and find pipes to decommission. While moving through the environment a low level map, in the form of an occupancy grid, along with detailed location of pipes in the environment are obtained. This paper deals only with the low level "reflex" of obstacle avoidance that is performed while the robot moves along its path as well as some of the higher level tasks involved in path planning and robot motion in order to negotiate through a hazardous environment. The overall high level interaction with the system is made as simple and user friendly as possible using a graphical interface to control high level tasks. All low level communications and processing are transparent. The robot used for experimentation is a wheeled mobile platform equipped with many different sensors including ultrasonic range sensors and cameras. A quick and efficient obstacle avoidance algorithm has been developed using sixteen ultrasonic range sensor and one infrared proximity sensor.< >
In this paper we present a computational approach for extracting three-dimensional structure of controllable resolution, depth of field, and accuracy, all made available at real-time speeds. This approach utilizes the...
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In this paper we present a computational approach for extracting three-dimensional structure of controllable resolution, depth of field, and accuracy, all made available at real-time speeds. This approach utilizes the spatial and the temporal gradients of the streams of images acquired using an actively controlled camera. Depending on the requirements of a particular task, appropriate parameters such as disparity value sought, the inter-frame camera displacement, and number of frames in a stream, are chosen to control the resolution, depth of field, and accuracy. The acquisition and processing of the image stream are done in real-time on a pipeline architecture based processor. Extensive experiments are presented to demonstrate the accuracy, controllability of depth of field and resolution, and ability to perform successfully in a variety of scenes. The system operated with no latency between the image acquisition and processing. The total acquisition and processing time in these experiments is in the range of 0.27 to 1.56 sec. The depth results have an accuracy of 85% to 92%.< >
A real-time correspondence based tracking algorithm is detailed. The system uses a pipeline processor, a general purpose processor, a camera and a display. The Minimum Noise and Correlation Energy (MINACE) filter is u...
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A real-time correspondence based tracking algorithm is detailed. The system uses a pipeline processor, a general purpose processor, a camera and a display. The Minimum Noise and Correlation Energy (MINACE) filter is used in the tracking algorithm as it provides a good combination of speed, accuracy and flexibility for the targeted hardware system. The system designed is fast and tracking is accomplished at a rate of 15 hz. The system is adaptive and does not rely on a previous model of the object; the training image for filter synthesis is acquired from previous image frames and the filter is synthesized online to accommodate 3-D variations of the target being tracked. The system tracks an object consistently as is demonstrated by the low deviation of the results in the evaluation. The correlation filter-based tracking algorithm has proved to be useful in our research in cooperative mobile robots. A visual servoing system has been implemented using this tracking algorithm for convoying of multiple mobile robots.< >
This paper presents a method to accurately and efficiently extract depth from a sequence of images. The method integrates two techniques of depth extraction, namely, spatial and temporal gradient analysis, and stereo ...
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This paper presents a method to accurately and efficiently extract depth from a sequence of images. The method integrates two techniques of depth extraction, namely, spatial and temporal gradient analysis, and stereo processing to enhance the reliability of the depth extraction. Spatial and temporal gradient analysis has been shown to provide depth in a highly efficient manner. However, due to the small image displacement used in this algorithm, depth with only limited precision can be computed. To enhance the precision, a stereo based matching is performed on the first frame and the last frame of the monocular sequence used in spatial and temporal gradient analysis. The stereo matching is limited to a small region, based on the results of the spatial and temporal gradient analysis. The performance of the approach is demonstrated through experiments with real scenes.< >
This paper presents a Radon transform-based approach to the detection of linear features in images characterized by high noise levels. This approach is based on the localized Radon transform where the intensity integr...
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This paper presents a Radon transform-based approach to the detection of linear features in images characterized by high noise levels. This approach is based on the localized Radon transform where the intensity integration is performed over short line segments rather than across the entire image. The algorithm, referred to as the feature space line detector (FSLD) algorithm, is tested on synthetic images of linear features with very high noise levels. The results of this testing demonstrate the algorithm's robustness in the presence of noise, as well as its ability to detect and localize linear features that are significantly shorter than the image dimensions or that display some curvature.< >
A distributed heterogeneous network of fuzzy control agents has been developed for reactive behavior-based control of an autonomous mobile robot This methodology allows the authors' vehicle, MARGE, to perform real...
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A distributed heterogeneous network of fuzzy control agents has been developed for reactive behavior-based control of an autonomous mobile robot This methodology allows the authors' vehicle, MARGE, to perform realistic tasks in unstructured environments. Control actions for the robot are generated by a colony of independent agents that compete and cooperate to determine the emergent motion of the vehicle. Fuzzy rules are used to implement a diverse array of real-time functions within one simple development environment. The authors' multi-layer approach differs from other methods that perform the fuzzy inference mapping in one step. Real-time control without special hardware is possible by using a singleton centroid calculation and by breaking complex behaviors down into simple modules.< >
A motion planning and self-referencing approach has been developed, simulated and applied to an actual robot. Although there are several novelties to these approaches, the fact that both are based on traversability ve...
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A motion planning and self-referencing approach has been developed, simulated and applied to an actual robot. Although there are several novelties to these approaches, the fact that both are based on traversability vectors (t-vectors) is one aspect of this research that is unique. Through their application it has been found that t-vectors enhance the detection of path obstructions and geometric beacons and expedite the identification of features that are visible (or hearable) to sensors in both static and dynamic environments. T-vectors also reduce the data size and complexity of standard V-graphs and variations thereof. This paper provides the t-vector models step-by-step so that the reader will be able to apply them to mobile robot motion planning and self-referencing.< >
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