Nelson Raymond Corby

Machine Vision for Robotics

This paper examines robotic vision and its relation to computer vision. The role of vision as a robotic sensory process is discussed and compared with the other robotic sensory processes. Some fundamentals of machine vision processing are discussed for the binary, gray-scale, and three-dimensional cases. The paper stresses the need for three-dimensional vision processing for robotic tasks. Architectures and control structures for several different vision processing approaches are explored.

Augmented reality telemanipulation system for nuclear reactor inspection

There has been an increasing need for faster and more reliable inspection of nuclear reactor vessels during scheduled inspection/refueling/repair outages. The inspection of such a complicated environment presents many challenges. During scheduled outages, the inspection platform (in our system a remotely operated miniature submarine) must be piloted efficiently to remote inspection locations, images and measurements of inspection locations presented to the human inspector, past information about this location recalled and viewed, and decisions made regarding repair activity scheduling. We are developing a new integrated system that employs augmented reality techniques to allow the inspection system operator to efficiently and reliably carry out these tasks. We describe a system that creates a realtime animated synthetic image of the underwater environment being inspected (drawn from CAD models of reactor components) in which a synthesized image of the inspection platform moves. The image is created with respect to an operator selected viewing point. A sensor measures the position and orientation of the actual mini-submarine, and these data are used by the graphics computer to continuously update the animated image. The images to be viewed can be either two or three dimensional. This information is used to assist in guiding the vehicle through the environment. The system display also integrates current inspection data (such as live video images) with past video frames or with past inspection reports and past data to allow fast and reliable inspection decisions to be made. Examples of typical operator display screens are included.

High-speed, high-resolution 3D range camera

There is a large class of machine vision inspection problems which requires detecting and characterizing voids in mostly diffuse materials. Typical examples include surface chips or gouges in ceramic parts, voids in powered metal components prior to sintering, and surface distress in construction and paving materials. There are two interrelated difficulties: achieving lighting which provides enough image contrast for reliable detection; developing image processing algorithms which can distinguish reliably between voids and image artifacts. The problems are particularly acute when inspecting composite materials containing dark inclusions which can be confused for voids, such as the aggregates in cementitious materials. We have examined this problem theoretically to understand the contrast-forming mechanisms. In this paper we present theoretical methods for modeling image contrast in images of small voids. We show how to use these methods to design appropriate illuminating systems and image processing algorithms. We validate the approach by comparing the theoretical results with experimental measurements. The prototype system we will discuss uses machine vision methods to measure air voids in cured and sectioned samples of portland cement concrete. These measurements allow estimation of air entrainment--a material property which, when properly controlled, can enhance the concretes ability to resist microcracking and structural deterioration during repeated cycles or freezing and thawing.

Signal-processing and acquisition challenges in realtime magnetic source imaging systems

As a result of a joint research agreement, we are currently building the data acquisition, visualization, analysis, and archiving systems for two research magnetic source imaging (MSI) systems to be placed at a new biomedical center in Europe. The MSI sensor heads are to be supplied by our partners. MSI is an emerging diagnostic modality which attempts to characterize the spatial and temporal electrical activity within the body (e.g. heart, brain, or spine) by noninvasive measurement of the external magnetic fields created by minute internal electrical currents. This paper briefly summarizes the nature of these signals and of MSI systems. It then develops the system design requirements suitable for clinical applications. The resulting heterogeneous, multiprocessor system based on these requirements is described.<<ETX>>