Active vision for reliable ranging: Cooperating focus,stereo, and vergence

This article addresses the problem of measuring reliabily the absolute three-dimensional position of objects in an unknown and cluttered scene. It circumvents the limitations of a single sensor or single algorithm by using several range recovery techniques together, so that they cooperate in visual behaviors similar to those exhibited by the human visual system. Implemented visual behaviors include (i) aperture adjustment to vary depth of field and contrast, (ii) focus ranging followed by fixation, (iii) stereo ranging followed by focus ranging, and (iv) focus ranging followed by disparity prediction followed by focus ranging. The main contribution is a demonstration that two particular visual ranging processes—focusing and stereo—can cooperate to improve measurement reliability. The results of 75 experiments processing close to 3000 different object points lying at distances between 1 and 3 meters demonstrate that the computed range values are highly reliable.     

Single-viewpoint, catadioptric cone mirror omnidirectional imaging theory and analysis

A family of catadioptric imaging systems has been developed that can achieve omnidirectional viewing with a single planar imager while still being able to recover perspective images, provided that they satisfy the single-viewpoint (SVP) constraint. It has been shown that the only mirror shapes that can have SVP when paired with a sole focusing planar imager camera are the surfaces of revolution of conic section curves. However, the special case of such a surface, the cone-shaped mirror itself, has not been deemed a viable SVP mirror shape. We present a comprehensive imaging theory of the cone mirror in its SVP configuration. We show that the SVP, cone mirror catadioptric system not only is practical but also has unique advantages for certain applications. The detailed theory explains why and how a practical SVP cone configuration can be set up, the merits and weaknesses of such systems, and how one can remedy the weaknesses to create a workable imaging system. We also derive the tolerance formula for estimating effects of alignment errors. A prototype has been constructed, and experimental results validate our theory.     

A methodology for evaluation of task performance in robotic systems: a case study in vision-based localization

We investigated the performance of an agent that uses visual information in a partially unknown and changing environment in a principled way. We propose a methodology to study and evaluate the performance of autonomous agents. We first analyze the system theoretically to determine the most important system parameters and to predict error bounds and biases. We then conduct an empirical analysis to update and refine the model. The ultimate goal is to develop self-diagnostic procedures. We show that although simple models can successfully predict some major effects, empirically observed performance deviates from theoretical predictions in interesting ways.     

Effect of Moisture on the Insulation Condition of Twisted Coils

Method IEEE 841 is used to test endurance of insulation system of stators to 100% humidity at 40 ℃ for168 h. Insulation resistance after this test between phases or between phase and frame has not been lover as 5 × 10^6 Ohm. Some producers of motors use this method for determining quality of impregation resin. On such test insulation resistance between phases was lover as between phase and frame. Because between phases is only wire insulation impregnating resins on insulation resistance of insulation system an impregnating resin we observe influence of type of wires and after humidity test. With diagnostic of insulation, the state is dealt. We compare our impregnation resin with competitive impregnation resin. We made test on twisted coils prepared after STN IEC from two parallel wires. In this test, we succeed in demonstrating that the main influence on insulation resistance of insulation system wire and impregnation resin has insulation of wire. Impregnation resin has influenced on data dispersion.     

Revisiting active perception

Despite the recent successes in robotics, artificial intelligence and computer vision, a complete artificial agent necessarily must include active perception. A multitude of ideas and methods for how to accomplish this have already appeared in the past, their broader utility perhaps impeded by insufficient computational power or costly hardware. The history of these ideas, perhaps selective due to our perspectives, is presented with the goal of organizing the past literature and highlighting the seminal contributions. We argue that those contributions are as relevant today as they were decades ago and, with the state of modern computational tools, are poised to find new life in the robotic perception systems of the next decade.     

Detection of diffuse and specular interface reflections and inter-reflections by color image segmentation

We present a computational model and algorithm for detecting diffuse and specular interface reflections and some inter-reflections. Our color reflection model is based on the dichromatic model for dielectric materials and on a color space, called S space, formed with three orthogonal basis functions. We transform color pixels measured in RGB into the S space and analyze color variations on objects in terms of brightness, hue and saturation which are defined in the S space. When transforming the original RGB data into the S space, we discount the scene illumination color that is estimated using a white reference plate as an active probe. As a result, the color image appears as if the scene illumination is white. Under the whitened illumination, the interface reflection clusters in the S space are all aligned with the brightness direction. The brightness, hue and saturation values exhibit a more direct correspondence to body colors and to diffuse and specular interface reflections, shading, shadows and inter-reflections than the RGB coordinates. We exploit these relationships to segment the color image, and to separate specular and diffuse interface reflections and some inter-reflections from body reflections. The proposed algorithm is effications for uniformly colored dielectric surfaces under singly colored scene illumination. Experimental results conform to our model and algorithm within the liminations discussed.     

Active Learning for Vision-Based Robot Grasping

Reliable vision-based grasping has proved elusive outside of controlled environments. One approach towards building more flexible and domain-independent robot grasping systems is to employ learning to adapt the robot's perceptual and motor system to the task. However, one pitfall in robot perceptual and motor learning is that the cost of gathering the learning set may be unacceptably high. Active learning algorithms address this shortcoming by intelligently selecting actions so as to decrease the number of examples necessary to achieve good performance and also avoid separate training and execution phases, leading to higher autonomy. We describe the IE-ID3 algorithm, which extends the Interval Estimation (IE) active learning approach from discrete to real-valued learning domains by combining IE with a classification tree learning algorithm (ID-3). We present a robot system which rapidly learns to select the grasp approach directions using IE-ID3 given simplified superquadric shape approximations of objects. Initial results on a small set of objects show that a robot with a laser scanner system can rapidly learn to pick up new objects, and simulation studies show the superiority of the active learning approach for a simulated grasping task using larger sets of objects. Extensions of the approach and future areas of research incorporating more sophisticated perceptual and action representation are discussed     

Discrete event modeling of visually guided behaviors

When visual behaviors are combined to provide a specific functionality needed for a task, the combination is often based on heuristic rules. In this article we show that by adopting the Discrete-Event Systems (DES) formalism for describing the interaction between visual behaviors it is possible to provide systems that have well-defined properties in terms of observability and controllability. The method is in particular suited for describing the coupling between action and perception. An introduction to the use of DES is provided and it is demonstrated how DES are used for modeling behaviors and controlling a mobile robot equipped with a binocular camera head and some additional sensors.     

CITRIS and data and knowledge engineering: What is old and what is new?

We survey the issues involved in knowledge capture and representation for the humanities and outline the design of a modern information system, which will permit humanities researchers to easily publish, share, view and process data. This system takes advantage of recent advances in the capture, representation, indexing and search of text and media data, including representations of three-dimensional images and three-dimensional enhancements of two-dimensional images. We suggest the exploitation of modern networking technologies to make electronic publication accessible to non-technologists. Finally, we discuss the problem of privacy in data mining and outline possible solutions from the recent literature.