2626294
Computation of shape through controlled active exploration
Accurate knowledge of depth continues to be of critical importance in robotic systems. Without accurate depth knowledge, tasks such as inspection, tracking, grasping, and collision-free motion planning prove to be difficult and often unattainable. Traditional visual depth recovery has relied upon techniques that require the solution of the correspondence problem or require known lighting conditions and Lambertian surfaces. In this paper, we present a technique for the derivation of depth from feature points on a target's surface using the controlled active vision framework. We use a single visual sensor mounted on the end-effector of a robotic manipulator to automatically select feature points and to derive depth estimates for those features using adaptive control techniques. Movements of the manipulator produce displacements that are measured using a sum-of-squared difference (SSD) optical flow. The measured displacements are fed into the controller to alter the path of the manipulator and to refine the depth estimate.<<ETX>>
5822992
Active Deformable Models Using Density Estimation
This paper introduces a new approach to active deformable models. The paper starts with a brief review of the relevant approaches. We then use the Expectation Maximization and Parzen Window techniques to develop a more robust formulation for pressure snakes. The generic nature of the proposed model allows it to perform well on complex colored images. We show, by several examples, the enhanced performance of the snake under the new formulation, compared to the performance of other known snake formulations.
41677043
Unknown object grasping using statistical pressure models
Grasping is one of the most fundamental and challenging tasks in robotics. Applications range from space missions (e.g., collection of rock samples) to industrial automation. In this work, we use a camera mounted on the end-effector of a manipulator to grasp an unknown object in the workspace. A novel deformable contour model is used to determine plausible grasp axes of the target object. Potential grasp point pairs are generated, ranked based upon measurements taken from the contour, and a vision-guided grasp of the object using the highest ranked grasp point pair is executed. Several experimental results are presented.
42411588
Computer vision issues during eye-in-hand robotic tasks
Our previous work has introduced the framework of controlled active vision that provides a bridge between computer vision and control theory. This paper presents some of the computer vision techniques that were employed in order to detect targets, automatically select features, measure feature displacements, and evaluate measurements during the various applications of the controlled active vision framework. We experimented with a lot of different techniques, but the most robust proved to be the sum-of-squared differences (SSD) optical flow technique. Search optimizations and dynamic pyramiding are proposed in order to provide real-time performance. In addition, several techniques for the evaluation of the measurements are presented. One important characteristic of these techniques is that they can also be used for the selection of features for tracking in conjunction with several numerical criteria that guarantee the robustness of the servoing. These techniques are important aspects of our work since they can be implemented either on-line or off-line. The paper concludes with results from the application of these techniques to real images.
14452564
Eye Tracking Using Active Deformable Models
Developing a robust, non-intrusive, inexpensive eye tracker is quite a challenge in the computer vision field. This paper introduces a new eye tracking approach based on an enhanced formulation of the statistical pressure snakes. Using a head-mounted camera, to eliminate the effect of head movements, we can detect and track the eye pupil robustly. Experimental results on video sequences for normal and blinking eyes are presented with high accuracy.
14698101
Experiences with electronic and voice mail
Organizational computing tools are often developed and managed with an eye toward increasing efficiency. Two of today's most widespread tools are electronic mail and voice mail. They are often considered similar asynchronous communication systems, one less rich than the other. We report usage results from a single firm which adopted both electronic mail and voice mail at the same time. Survey respondents view technologies as vital to accomplishing business, but use them in quite different ways. Electronic mail was utilized to communicate with all personnel equally. In contrast, respondents communicated with their peers using voice mail more than they did up or down the corporate hierarchy. The technologies were used differently for internal and external communication. Both of these results fly in the face of information richness theory.
9601024
Using COTS to Construct a High Performance Robot Arm
In this paper we present a design study and technical specifications of a high performance robotic manipulator to be used for ball catching experiments using commercial off-the-shelf (COTS) components. Early evaluation shows that very good performance can be achieved using standardized PowerCube actuator modules from Amtec and a standard workstation using CAN bus communication. Implementation issues of low-level control and software platform are also described, as well as early experimental evaluation of the system.
16135450
Software Performance AntiPatterns; Common Performance Problems and their Solutions
A pattern is a common solution to a problem that occurs in many different contexts. Pat- terns capture expert knowledge about "best practices" in software design in a form that allows that knowledge to be reused and applied in the design of many different types of software. Antipatterns are conceptually similar to patterns in that they document recurring solutions to common design problems. They are known as antipatterns because their use (or misuse) produces negative consequences. Antipatterns document common mistakes made during software development as well as their solutions. While both patterns and antipatterns can be found in the literature, they typically do not explicitly consider performance consequences. This paper explores antipatterns from a performance perspective. We propose four new performance antipatterns that often occur in software systems.
10892913
Web Application Scalability: A Model-Based Approach
Scalability is one of the most important quality attributes of today’s software systems. Yet, despite its importance, scalability in applications is poorly understood. This paper presents a model-based view of scalability in Web and other distributed applications that is aimed at removing some of the myth and mystery surrounding this important software quality. We review four models of scalability and show how they relate to Web and other distributed applications. The applicability of these models is demonstrated with a case study.
10134033
SPE Evaluation of a Client/Server Application
This paper presents the results of a software performance evaluation of a client/server application in an Open Systems environment. Some interesting features of the design and the graphical user interface are described and their performance characteristics are evaluated. The evaluation uses a new Software Performance Engineering (SPE) tool to create software models and evaluate design alternatives.