62 research outputs found

    Multisensor knowledge systems: interpreting 3-D structure

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    Journal ArticleWe describe an approach which facilitates and makes explicit the organization of the knowledge necessary to map multisensor system requirements onto an appropriate assembly of algorithms, processors, sensors, and actuators. We have previously introduced the Multisensor Kernel System and Logical Sensor Specifications as a means for high-level specification of multisensor systems. The main goals of such a characterization are: to develop a coherent treatment of multisensor information, to allow system reconfiguration for both fault tolerance and dynamic response to environmental conditions, and to permit the explicit description of control. In this paper we show how Logical Sensors can be incorporated into an object-based approach for the interpretation of 3-D structure. Considering the inherent difficulties in interpreting general configurations of lines in space, and considering the ubiquitousness of special line configurations in man-made environments and objects, we advocate the use of computational units tuned to the occurrence of special configurations. The organized use of these units circumvents the inherent difficulties in interpreting general configurations of lines. After a brief examination of the problem of interpreting general configurations of lines in space, a number of computational units are proposed which are naturally derived from angular relations. The process of propagation (which allows interpretation to spread over the image) is also advocated. Such computational units and processes, which are simple and efficient, can be conveniently organized in a rule-based framework where the occurrence of the various special configurations can be tested. The Multisensor Knowledge System provides such a framework

    Proposal For a Study of Commonsense Physical Reasoning

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    This report describes research done at the Artificial Intelligence Laboratory of the Massachusetts Institute of Technology. Support for the laboratory's artificial intelligence research is provided in part by the Advanced Research Projects Agency of the Department of Defense under Office of Naval Research contract N00014-80-C-0505.Our common sense views of physics are the first coin in our intellectual capital; understanding precisely what they contain could be very important both for understanding ourselves and for making machines more like us. This proposal describes a domain that has been designed for studying reasoning about constrained motion and describes my theories about performing such reasoning. The issues examined include qualitative reasoning about shape and physical processes, as well as ways of using knowledge about motion other than "envisioning". Being a proposal, the treatment of these issues is necessarily cursory and incomplete.MIT Artificial Intelligence Laboratory Department of Defense Advanced Research Projects Agenc

    Knowledge-based 2-D vision system synthesis

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    technical reportA knowledge-based approach to computer vision provides the needed flexibility for performing recognition and inspection of objects in a complex environment. A system is described which uses knowledge about the environment, sensors, and performance requirements to construct a functional configuration of sensors and algorithms. The system uses an object-based approach to synthesize both the analytical model for an object and the executable application system

    Modelling Reactive Multimedia: Design and Authoring

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    Multimedia document authoring is a multifaceted activity, and authoring tools tend to concentrate on a restricted set of the activities involved in the creation of a multimedia artifact. In particular, a distinction may be drawn between the design and the implementation of a multimedia artifact. This paper presents a comparison of three different authoring paradigms, based on the common case study of a simple interactive animation. We present details of its implementation using the three different authoring tools, MCF, Fran and SMIL 2.0, and we discuss the conclusions that may be drawn from our comparison of the three approaches

    Discontinuity Preserving Regularization for Modeling Sliding in Medical Image Registration

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    Sliding effects often occur along tissue/organ boundaries. However, most conventional registration techniques either use smooth parametric bases or apply homogeneous smoothness regularization, and fail to address the sliding issue. In this study, we propose a class of discontinuity-preserving regularizers that fit naturally into optimization-based registration. The proposed regularization encourages smooth deformations in most regions, but preserves large discontinuities supported by the data. Variational techniques are used to derive the descending flows. We discuss general conditions on such discontinuity-preserving regularizers, and their properties based on an anisotropic filtering interpretation. Preliminary tests with 2D CT data show promising results.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/85986/1/Fessler234.pd

    Temporal Reasoning About Robotics Applications: Refinement and Temporal Logic

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    The challenges of verifying the behaviour of robotics systems has motivated the development of various techniques and tools for supporting the advancement and verification of robotics systems. This is due to the complex nature of verifying robotics systems as part of the category of hybrid dynamical systems that combine discrete and continuous parts. In contrast to the commonly-known computer systems, robotic sys- tems operate in a physical, real-world environment that may include humans, which raises a reasonable question of concern about the safety of the systems. Currently, one of the promising solutions is effective, rigorous verification techniques and tools that verify and guarantee the safe operation of robotics systems. Along this line, formal methods provide mathematical models that support the de- velopment of rigorous verification techniques and tools. In this work, we use formal methods for the verification of temporal specifications of robotics systems. The process algebra tock-CSP provides textual notations for modelling discrete-time behaviours, with the support of various tools for verification. Also, tock-CSP has been used to give semantics to a domain-specific language for robotics, RoboChart. Similarly, automatic verification of Timed Automata (TA) is supported by the real-time verification toolbox Uppaal that facilitates verification of temporal specifications using Time Computation Tree Logic (TCTL). Timed Automata and tock-CSP differ in both modelling and verification approaches. For instance, liveness requirements are difficult to specify with the constructs of tock-CSP, but they are easy to verify in Uppaal. In this work, we add a step forward in translating tock-CSP into TA to take advantage of Uppaal. We have developed a translation technique and tool; our work uses rules for translating tock-CSP into a network of small TAs, which address the complexity of capturing the compositionality of tock-CSP. For the validation of our proposed con- tributions, we use an experimental approach based on finite approximations to trace sets. We consider trace semantics for validating the translation technique. Thus, we develop a technique for generating and comparing traces of tock-CSP and TA. In order to evaluate the translation technique and its corresponding tool, we use two forms of test cases: a large collection of small processes and case studies from the literature. We illustrate a plan for using mathematical proof to establish the correctness of the rules that will cover an infinite set of traces

    USSR Space Life Sciences Digest, issue 1

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    The first issue of the bimonthly digest of USSR Space Life Sciences is presented. Abstracts are included for 49 Soviet periodical articles in 19 areas of aerospace medicine and space biology, published in Russian during the first quarter of 1985. Translated introductions and table of contents for nine Russian books on topics related to NASA's life science concerns are presented. Areas covered include: botany, cardiovascular and respiratory systems, cybernetics and biomedical data processing, endocrinology, gastrointestinal system, genetics, group dynamics, habitability and environmental effects, health and medicine, hematology, immunology, life support systems, man machine systems, metabolism, musculoskeletal system, neurophysiology, perception, personnel selection, psychology, radiobiology, reproductive system, and space biology. This issue concentrates on aerospace medicine and space biology

    Robotic System Development for Precision MRI-Guided Needle-Based Interventions

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    This dissertation describes the development of a methodology for implementing robotic systems for interventional procedures under intraoperative Magnetic Resonance Imaging (MRI) guidance. MRI is an ideal imaging modality for surgical guidance of diagnostic and therapeutic procedures, thanks to its ability to perform high resolution, real-time, and high soft tissue contrast imaging without ionizing radiation. However, the strong magnetic field and sensitivity to radio frequency signals, as well as tightly confined scanner bore render great challenges to developing robotic systems within MRI environment. Discussed are potential solutions to address engineering topics related to development of MRI-compatible electro-mechanical systems and modeling of steerable needle interventions. A robotic framework is developed based on a modular design approach, supporting varying MRI-guided interventional procedures, with stereotactic neurosurgery and prostate cancer therapy as two driving exemplary applications. A piezoelectrically actuated electro-mechanical system is designed to provide precise needle placement in the bore of the scanner under interactive MRI-guidance, while overcoming the challenges inherent to MRI-guided procedures. This work presents the development of the robotic system in the aspects of requirements definition, clinical work flow development, mechanism optimization, control system design and experimental evaluation. A steerable needle is beneficial for interventional procedures with its capability to produce curved path, avoiding anatomical obstacles or compensating for needle placement errors. Two kinds of steerable needles are discussed, i.e. asymmetric-tip needle and concentric-tube cannula. A novel Gaussian-based ContinUous Rotation and Variable-curvature (CURV) model is proposed to steer asymmetric-tip needle, which enables variable curvature of the needle trajectory with independent control of needle rotation and insertion. While concentric-tube cannula is suitable for clinical applications where a curved trajectory is needed without relying on tissue interaction force. This dissertation addresses fundamental challenges in developing and deploying MRI-compatible robotic systems, and enables the technologies for MRI-guided needle-based interventions. This study applied and evaluated these techniques to a system for prostate biopsy that is currently in clinical trials, developed a neurosurgery robot prototype for interstitial thermal therapy of brain cancer under MRI guidance, and demonstrated needle steering using both asymmetric tip and pre-bent concentric-tube cannula approaches on a testbed
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