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A system for facial reconstruction using distraction and symmetry considerations

International Congress Series 2001年第C期1230卷 62-67页

作者： Burgert, O. Salb, T. Gockel, T. Dillmann, R. Hassfeld, S. Brief, J. Krempien, R. Walz, S. Mühling, J. Institute of Real-Time Computer Systems and Robotics University of Karlsruhe D-76128 Karlsruhe Gebaude 07.21 Kaiserstr. 12 Germany Department of Oral and Maxillofacial Surgery University of Heidelberg D-69120 Heidelberg Germany Department of Radiology University of Heidelberg D-69120 Heidelberg Germany

The goal of the system presented in this paper is to support several facial surgeries that are aiming to transform an unsymmetrical face to a symmetric one. There are two main techniques to achieve this goal: distraction of the lower jaw and adding or removing tissue or bone at certain facial regions. Both planning tasks are done based on segmented CT or MRI data. The distraction of the lower jaw is simulated by cutting the jaw, moving it in 3D along a distraction axis and choosing a distractor for this procedure after determining, which is the best result. Furthermore, we are working on consideration of soft tissue movement so the patient can see what he or she will look like after the surgery. For supporting implants in craniofacial surgery, we are proposing a tool based on symmetry considerations. Nowadays, if implants have to be fitted to the patient's bone, they are handmade while the surgery is running. This is quite time consuming and it would be helpful to shorten this procedure by producing the implants preoperatively. Our system allows to determine regions where implants should be set and proposes an initial contour for the implants. © 2001 Elsevier Science B.V.

关键词： Distraction Face Symmetry

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Robot assistant for dental implantology 4th

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4th International Conference on Medical Image Computing and computer-Assisted Intervention, MICCAI 2001

作者： Boesecke, R. Brief, J. Raczkowsky, J. Schorr, O. Daueber, S. Krempien, R. Treiber, M. Wetter, T. Hassfeld, S. TaMed GmbH Hufschmiedstr. ¼ WieslochD-69168 Germany Department of Oral and Maxillofacial Surgery University Hospital Heidelberg Germany Department of Radiology University Hospital Heidelberg Germany Institute of Real-Time Computer Systems and Robotics University of Karlsruhe Germany Department of Medical Informatics University Hospital Heidelberg Germany

ISBN: (纸本)3540426973

We introduce a method to apply a preoperative 3D plan for inserting dental implants with an assisting medical robot. The treatment plan is based on the 3D visualization of the CT data of the patient.s maxilla and mandible, and supplies the location of the implants in the patient.s coordinates. The plan is then transferred to the surgical robot.s coordinate system. The robot guides the tool, a drill guide. Position, orientation, and depth of the initial drilling is defined with the tool held by the robot while the surgeon drills. The robot assists the dentist, and the optimal treatment plan will be applied directly to the patient. © Springer-Verlag Berlin Heidelberg 2001.

关键词： Drills

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Implementation and evaluation of a best-effort scheduling algorithm in an embedded real-time system

Implementation and evaluation of a best-effort scheduling al...

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IEEE International Symposium on Performance Analysis of systems and Software

作者： Peng Li B. Ravindran T. Hegazy Real Time Systems Laboratory The Bradley Department of Electrical and Computer Engineering Virginia Polytechnic Institute and State University Blacksburg VA USA

ISBN: (纸本)0780372301

This paper describes an implementation and the performance evaluation of the DASA/ND best-effort scheduling algorithm [4] in the μClinux/μCsimm micro-controller system. Experimental results under synthetic workload show that in some cases, the DASA/ND scheduler outperforms both the EDF (Earliest Deadline First) and the RMS (Rate Monotonic Scheduling) schedulers [7]. Meanwhile, the system performance gracefully degrades as the aggregate CPU load increases. However, the scheduling overhead, in general, is not negligible, which may lead to poorer performance than non best-effort scheduling algorithms. It is found that the scheduling overhead strongly depends on the task set properties. Using the Regression Analysis technique, we developed a statistical model accounting for the scheduling overhead. We show that this model, combined with a simulation tool can well predict the system performance.

关键词： Scheduling algorithm real time systems Neodymium Predictive models System performance Degradation Aggregates Regression analysis Analytical models Operating systems

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Bounding the execution time of real-time tasks on modern processors 7

Bounding the execution time of real-time tasks on modern pro...

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7th International Conference on real time Computing systems and Applications

作者： Petters, SM Institute for Real-Time Computer Systems Germany Technische Universität München Germany

ISBN: (纸本)0769509304

Finding a fight estimate on the execution time of tasks in embedded hard real-time systems is gaining complexity and importance. Uptodate processors are equipped with acceleration techniques to bridge the gap between the fast core frequency of the processors and the comparably slow main memory. On the other hand the application field of real-time systems is continuously widening to more complex systems. To keep up with the evolution of processors it is proposed to bay more weight on measurement and less an modeling. By analyzing the control flow graph the compiler uses for optimization, systematic information an how the code has to be measured can be gained. Using this information the code can be automatically instrumented and measured to bound the execution time of the real-time tasks.

关键词： Acceleration Automatic control Bridges Control system analysis Control systems Flow graphs Frequency Information analysis real time systems Weight measurement

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3D norm data: The first step towards semiautomatic virtual craniofacial surgery

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computer Aided Surgery 2001年第5期5卷

作者： J. Brief S. Hassfeld S. Däuber A. Pernozzoli J. Münchenberg T. Redlich M. Walz R. Krempien H. Weisser C. Poeckler J. Raczkowsky O. Burgert T. Salb B. Kotrikova U. Rembold H. Wörn R. Dillmann J. Mühling Departments of Oral and Maxillofacial Surgery (J.B. S.H. A.P. T.R. B.K. J.Müh.) and Radiology (R.K.) University of Heidelberg Heidelberg Department of Radiology University of Heidelberg Mannheim (M.W. H.W. C.P.) and Institute of Real-Time Computer Systems and Robotics University of Karlsruhe Karlsruhe (S.D. J.Mün. J.R. O.B. T.S. U.R. H.W. R.D.) Germany

When planning craniofacial surgical interventions, the ideal appearance of the patient is very important. The final appearance should be as close as possible to that which the patient would have if he/she were without defects. Our first step towards achieving this is to build a database containing sets of three-dimensional CT images that allows for comparison of the shape of a patient with defects to the typical shape of an age- and sex-matched “average” person without defects. We started to collect CT data from patients without pathologies and, in co-operation with two radiology institutes (in Mannheim and Heidelberg), over 100 CT data sets have now been collected and classified according to age and sex. It is necessary to choose an appropriate statistical method to calculate the norm data from the different data sets. Based on the statistical method, an age- and sex-matched “average” model of the anatomy will be created. Comp Aid Surg 5:353–358 (2000). © 2000 Wiley-Liss, Inc.

关键词： 3D norm data virtual healing virtual craniofacial surgery

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real-time obstacle avoidance using an MPEG-processor-based optic flow sensor

Real-time obstacle avoidance using an MPEG-processor-based o...

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15th International Conference on Pattern Recognition, ICPR 2000

作者： Stöffler, Norbert O. Burkert, Tim Farber, Georg Institute for Real-Time Computer Systems Technische Universität München MünchenD-80333 Germany

ISBN: (纸本)0769507506

This paper Describes a vision system for obstacle detection in mobile robot navigation. The system uses an image processing board equipped with an MPEG motion estimation processor that calculates a robust optic-flow-like vector field in real-time. This field is then evaluated by algorithms running in software on the host PC. As the solutions to the general problem of structure and motion from optic flow are too instable for the use in this application, the typical constraints of mobile robotics are exploited, i.e. A reduced set of motion parameters and a known ground plane. Ego-motion can then be reconstructed with robust one dimensional methods. A new criterion for obstacles that copes well with the noise properties of the motion field is introduced. For vectors belonging to obstacles the 3D information is reconstructed allowing not only qualitative detection of obstacles but quantitative path planning. © 2000 IEEE.

关键词： Motion estimation

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End user specication of RoboCup teams 3rd

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3rd Robot World Cup Soccer Games and Conferences, RoboCup 1999

作者： Scerri, Paul Ydrén, Johan Real-time Systems Laboratory Department of Computer and Information Science Linköpings Universitet LinköpingS-581 83 Sweden Institute for Computer Science Linkpings Universitet Sweden

ISBN: (纸本)9783540410430

Creating complex agents for simulation environments has long been the exclusive realm of AI experts. However it is far more desirable that experts in the particular application domain, rather than AI experts, are empowered to specify agent behavior. In this paper an approach is presented that allows domain experts to specify the high-level team strategies of agents for RoboCup. The domain experts’ specications are compiled into behavior based agents. The 1999 RoboCup World Cup provided an interesting basis for evaluation of the approach. We found that for RoboCup it is not necessary to allow a user to change low level aspects of the agents’ behavior in order for them to create a range of different, interesting teams. We also found that the modular nature of behavior based architectures make them an ideal target architecture for compiling enduser specications. © Springer-Verlag Berlin Heidelberg 2000.

关键词： Artificial intelligence

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Integration of COTS components with a DSP coprocessor for microstereolithography machine control

Integration of COTS components with a DSP coprocessor for mi...

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IEEE Conference on Control Technology and Applications (CCTA)

作者： G. Burmberger C. Farber Institute for Real-time Computer Systems Technische Universitat Munchen Germany

Prototyping is a process of building pre-production models of a product to test various aspects of its design. Stereolithography (STL) is a rapid prototyping technique that allows us to quickly produce physical prototypes with the important benefit of reducing the time-to-market. The resulting design cost will be decreased considerably. Usually it has only an average precision of about 200 /spl mu/m and the machines are built of particularly expensive components. The paper presents an approach for the integration of commercial off-the-shelf (COTS) components with a PCI bus digital signal processor board for complete control of a highly precise microstereolithography machine. Two scanners and one acoustooptical modulator that are directly controlled by the DSP realize the deflection and switching of the laser beam. The main goal is to ensure real-time data flow throughout the whole process of exposure so that no missing coordinates or "hot spots" occur. During the development, we focused on the use of standard programming languages like C and C++, standard operating systems like Windows NT and hardware components for the well-introduced PCI bus. These endeavors lead to our prototype of a microstereolithographry machine that is suitable for the growing needs of the microsystem technology industry.

关键词： Digital signal processing Coprocessors Prototypes Standards development Buildings Testing Stereolithography time to market Costs Digital signal processors

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An evaluation of code generation strategies targeting hardware for the rapid prototyping of SDL specifications

An evaluation of code generation strategies targeting hardwa...

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International Workshop on Rapid System Prototyping (RSP)

作者： A. Muth T. Kolloch T. Maier-Komor G. Farber Institute for Real Time Computer Systems Technische Universitat Munchen Germany

The specification of an embedded system at the system level, together with co-joint hardware/software synthesis, is a goal of many rapid prototyping projects. SDL has been proposed as a formal and abstract specification language that is well-suited for this purpose. In the automated generation of hardware, however, SDL's asynchronous communication model (directly implemented in the so-called server model) can lead to large overheads in area and response time. The activity thread implementation model, on the other hand, is more similar to hardware description language concepts, with respect to its execution in hardware, due to its synchronous communication and execution scheme. This paper compares VHDL code generation from SDL using these two models, with regard to their implementation architectures, resource usage, throughput and response time. The integration in an existing rapid prototyping design process is presented, as well as results gained from several application examples.

关键词： Delay Embedded system Embedded software Software prototyping Specification languages Asynchronous communication Yarn Hardware design languages Throughput Prototypes

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Photo-realistic scene prediction of partially unknown environments for the compensation of time delays in telepresence applications

Photo-realistic scene prediction of partially unknown enviro...

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IEEE International Conference on robotics and Automation (ICRA)

作者： M. Barth T. Burkert C. Eberst N.O. Stoffler G. Farber Institute for Real-Time Computer Systems Technische Universitat Munchen Munich Germany

Predictive displays have proven their suitability to compensate time delays in visual feedback which impair the performance of teleoperation applications. Most current implementations employ simple computer graphics for the prediction of the visual feedback given to the operator who is controlling the remote manipulation. Furthermore, they require a well-known remote environment. The aim of the presented work is to improve the efficacy of the predictive display by increasing the degree of immersion and by enhancing the system's flexibility. Potential applications include maintenance and repair of machines located in remote plant- or office-type environments, which are typically non-static and a priori only partially known. Communication media are high- and medium-bandwidth LANs and WANs inducing round trip delays varying from 0.2 to 2 seconds. Additionally, a sufficient bandwidth cannot be assured during the entire remote operation. The paper describes a predictive display system which achieves photo-realism based on autonomously explored and updated scene models. Model acquisition is performed with a binocular CCD camera system. Photo-realism is obtained by using computer graphics techniques, especially the mapping of original, real textures. Besides the concepts, an early stage of implementation and first experimental results in scene reconstruction and photo-realistic scene prediction are presented.

关键词： Layout computer displays Feedback computer graphics Delay effects Application software Bandwidth Predictive models Charge coupled devices Charge-coupled image sensors

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