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2001


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Wing transmission for a micromechanical flying insect

Yan, J., Avadhanula, S., Birch, J., Dickinson, M., Sitti, M., Su, T., Fearing, R.

Journal of Micromechatronics, 1(3):221-237, Brill, 2001 (article)

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[BibTex]

2001


[BibTex]


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Spontaneous L12 order at Ni90Al10(110) surfaces: An X-ray and first-principles-calculation study

Drautz, R., Reichert, H., Fähnle, M., Dosch, H., Sanchez, J. M.

{Physical Review Letters}, 87(23), 2001 (article)

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[BibTex]

[BibTex]


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Magnetic viscosity and demagnetization behaviour in isotropic nanocrystalline Pr12Fe82B6 ribbons

Zhang, H. W., Zhang, S. Y., Shen, B. G., Goll, D., Kronmüller, H.

{Chinese Physics}, 10(12):1169-1171, 2001 (article)

mms

[BibTex]

[BibTex]


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Materials analysis with monolayer depth resolution using MeV ion beams

Carstanjen, H. D.

In 117, Las Vegas, USA, 2001 (inproceedings)

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[BibTex]

[BibTex]


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Strain relaxation and internal friction in the range of the glass transition

Ege, M., Ulfert, W., Kronmüller, H.

{Zeitschrift f\"ur Metallkunde}, 92(7):690-694, 2001 (article)

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[BibTex]

[BibTex]


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Hardness-depth profiling on nanometer scale

Kunert, M., Baretzky, B., Baker, S. P., Mittemeijer, E. J.

{Metallurgical and Materials Transactions A-Physical Metallurgy and Materials Science}, 32(5):1201-1209, 2001 (article)

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[BibTex]

[BibTex]


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Compound formation and abrasion resistance of ion-implanted Ti6Al4V

Schmidt, H., Schminke, A., Schmiedgen, M., Baretzky, B.

{Acta Materialia}, 49(3):487-495, 2001 (article)

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[BibTex]

[BibTex]


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Influence of vortex-vortex interaction on critical currents across low-angle grain boundaries in YBa2Cu3O7-δthin films

Albrecht, J., Leonhardt, S., Kronmüller, H.

{Physical Review B}, 63, 2001 (article)

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[BibTex]

[BibTex]


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Structure of superconducting [BaCuOx]2/[CaCuO2]n superlattices on SrTiO3(001) investigated by x-ray scattering

Aruta, C., Zegenhagen, J., Cowie, B., Balestrino, G., Pasquini, G., Medaglia, P. G., Ricci, F., Luebbert, D., Baumbach, T., Riedo, E., Ortega, L., Kremer, R., Albrecht, J.

{Physica Status Solidi (A)}, 183, pages: 353-364, 2001 (article)

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[BibTex]

[BibTex]


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Flux-line pinning in low-angle grain boundaries.

Albrecht, J., Leonhardt, S., Kronmüller, H.

In Proceedings 10th International Workshop on Critical Currents (IWCC 2001), pages: 41-43, Göttingen, Germany, 2001 (inproceedings)

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[BibTex]

[BibTex]


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Transmission X-ray microscopy using X-MCD

Eimüller, T., Fischer, P., Köhler, M., Scholz, M., Guttmann, P., Denbeaux, G., Glück, S., Bayreuther, G., Schmahl, G., Attwood, D., Schütz, G.

{Applied Physics A}, 73, pages: 697-701, 2001 (article)

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[BibTex]

[BibTex]


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Soft X-ray microscopy to 25 nm with applications to biology and magnetic materials

Denbeaux, G., Anderson, E., Chao, W., Eimüller, T., Johnson, L., Köhler, M., Larabell, C., Legros, M., Fischer, P., Pearson, A., Schütz, G., Yager, D., Attwood, D.

{Nuclear Instruments and Methods in Physics Research A}, 467-468, pages: 841-844, 2001 (article)

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[BibTex]

[BibTex]


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Study of in-plane magnetic domains with magnetic transmission X-ray microscopy

Fischer, P., Eimüller, T., Schütz, G., Köhler, M., Bayreuther, G., Denbeaux, G., Attwood, D.

{Journal of Applied Physics}, 89, pages: 7159-7161, 2001 (article)

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[BibTex]

[BibTex]


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Influence of vortex-vortex interaction on critical currents across low-angle grain boundaries in YBa2Cu3O7-δthin films

Albrecht, J., Leonhardt, S., Kronmüller, H.

{Physical Review B}, 63, 2001 (article)

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[BibTex]

[BibTex]


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Non-symmetric influences in the total electron yield X-ray magnetic circular dichroism signal in applied magnetic fields

Goering, E., Gold, S., Bayer, A., Schütz, G.

{Journal of Synchrotron Radiation}, 8, pages: 434-436, 2001 (article)

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DOI [BibTex]

DOI [BibTex]


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Effect of Ga substitution on the magnetocrystalline anisotropy of arc-melted Sm2Co17-xGax (x\textequals5,6) compounds

Liang, B., Kleinschroth, I., Kronmüller, H.

{Journal of Applied Physics}, 89(1):488-491, 2001 (article)

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[BibTex]

[BibTex]


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Influence of grain boundary phase transitions on the properties of Cu-Bi polycrystals

Straumal, B. B., Sluchanko, N.E., Gust, W.

In Defects and Diffusion in Metals III: An Annual Retrospective III, 188-1, pages: 185-194, Defect and Diffusion Forum, 2001 (incollection)

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[BibTex]

[BibTex]


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Learning inverse kinematics

D’Souza, A., Vijayakumar, S., Schaal, S.

In IEEE International Conference on Intelligent Robots and Systems (IROS 2001), Piscataway, NJ: IEEE, Maui, Hawaii, Oct.29-Nov.3, 2001, clmc (inproceedings)

Abstract
Real-time control of the endeffector of a humanoid robot in external coordinates requires computationally efficient solutions of the inverse kinematics problem. In this context, this paper investigates learning of inverse kinematics for resolved motion rate control (RMRC) employing an optimization criterion to resolve kinematic redundancies. Our learning approach is based on the key observations that learning an inverse of a non uniquely invertible function can be accomplished by augmenting the input representation to the inverse model and by using a spatially localized learning approach. We apply this strategy to inverse kinematics learning and demonstrate how a recently developed statistical learning algorithm, Locally Weighted Projection Regression, allows efficient learning of inverse kinematic mappings in an incremental fashion even when input spaces become rather high dimensional. The resulting performance of the inverse kinematics is comparable to Liegeois ([1]) analytical pseudo inverse with optimization. Our results are illustrated with a 30 degree-of-freedom humanoid robot.

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link (url) [BibTex]

link (url) [BibTex]


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Biomimetic smooth pursuit based on fast learning of the target dynamics

Shibata, T., Schaal, S.

In IEEE International Conference on Intelligent Robots and Systems (IROS 2001), 2001, clmc (inproceedings)

Abstract
Following a moving target with a narrow-view foveal vision system is one of the essential oculomotor behaviors of humans and humanoids. This oculomotor behavior, called ``Smooth Pursuit'', requires accurate tracking control which cannot be achieved by a simple visual negative feedback controller due to the significant delays in visual information processing. In this paper, we present a biologically inspired and control theoretically sound smooth pursuit controller consisting of two cascaded subsystems. One is an inverse model controller for the oculomotor system, and the other is a learning controller for the dynamics of the visual target. The latter controller learns how to predict the target's motion in head coordinates such that tracking performance can be improved. We investigate our smooth pursuit system in simulations and experiments on a humanoid robot. By using a fast on-line statistical learning network, our humanoid oculomotor system is able to acquire high performance smooth pursuit after about 5 seconds of learning despite significant processing delays in the syste

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link (url) [BibTex]

link (url) [BibTex]


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Biomimetic oculomotor control

Shibata, T., Vijayakumar, S., Conradt, J., Schaal, S.

Adaptive Behavior, 9(3/4):189-207, 2001, clmc (article)

Abstract
Oculomotor control in a humanoid robot faces similar problems as biological oculomotor systems, i.e., capturing targets accurately on a very narrow fovea, dealing with large delays in the control system, the stabilization of gaze in face of unknown perturbations of the body, selective attention, and the complexity of stereo vision. In this paper, we suggest control circuits to realize three of the most basic oculomotor behaviors and their integration - the vestibulo-ocular and optokinetic reflex (VOR-OKR) for gaze stabilization, smooth pursuit for tracking moving objects, and saccades for overt visual attention. Each of these behaviors and the mechanism for their integration was derived with inspiration from computational theories as well as behavioral and physiological data in neuroscience. Our implementations on a humanoid robot demonstrate good performance of the oculomotor behaviors, which proves to be a viable strategy to explore novel control mechanisms for humanoid robotics. Conversely, insights gained from our models have been able to directly influence views and provide new directions for computational neuroscience research.

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link (url) [BibTex]

link (url) [BibTex]


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Development of a scaled teleoperation system for nano scale interaction and manipulation

Sitti, M., Aruk, B., Shintani, H., Hashimoto, H.

In Robotics and Automation, 2001. Proceedings 2001 ICRA. IEEE International Conference on, 1, pages: 860-867, 2001 (inproceedings)

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[BibTex]

[BibTex]


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Irradiation-induced electron tunnelling and small-polaron hopping in single-crystalline YIG

Walz, F., Brabers, J. H. V. J., Torres, L., Kronmüller, H.

{Physica Status Solidi B-Basic Research}, 228(3):717-730, 2001 (article)

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[BibTex]

[BibTex]


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Kernspinresonanzuntersuchungen zur Diffusion von Wasserstoff in den Di- und Trihydriden der Übergangsmetalle

Gottwald, J.

Universität Stuttgart, Stuttgart, 2001 (phdthesis)

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[BibTex]


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Hexagonally ordered 100 nm period nickel nanowire arrays

Nielsch, K., Wehrspohn, R. B., Barthel, J., Kirschner, J., Gösele, U., Fischer, S. F., Kronmüller, H.

{Applied Physics Letters}, 79(9):1360-1362, 2001 (article)

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[BibTex]

[BibTex]


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Magnetization processes in isotropic and textured Nd2Fe14B- films

Melsheimer, A., Kronmüller, H.

{Physica B}, 299(3-4):251-259, 2001 (article)

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[BibTex]

[BibTex]


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Critical magnetic properties of disordered Cr-rich FeCr alloys

Fischer, S. F., Kaul, S. N., Kronmüller, H.

{Journal of Magnetism and Magnetic Materials}, 226(Sp. Iss. SI):540-541, 2001 (article)

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[BibTex]

[BibTex]


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Fast ab initio methods for the calculation of adiabatic spin wave spectra in complex systems

Grotheer, O., Ederer, C., Fähnle, M.

{Physical Review B}, 63(10):100401-100401, 2001 (article)

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[BibTex]

[BibTex]


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Hydrogen storage in sonicated carbon materials

Hirscher, M., Becher, M., Haluska, M., Dettlaff-Weglikowska, U., Quintel, A., Duesberg, G. S., Choi, Y. M., Downes, P., Hulman, M., Roth, S., Stepanek, I., Bernier, P.

{Applied Physics A-Materials Science \& Processing}, 72(2):129-132, 2001 (article)

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[BibTex]

[BibTex]


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Measurement of the low-temperature self-diffusivity of lithium by elastic recoil detection analysis

Wieland, O., Carstanjen, H. D.

In Proceedings of DIMAT 2000, the Fifth International Conference on Diffusion in Materials, 194/199, pages: 35-41, Defect and Diffusion Forum, Scitec Publications Ltd., Paris, France, 2001 (inproceedings)

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[BibTex]

[BibTex]


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Co(NH3)2Cl2 and Co(ND3)2Cl2: Order-Disorder Behaviour of N(H,D)3 and Antiferromagnetic Structure

Leineweber, A., Jacobs, H., E\ssmann, P., Allenspach, F., Fauth, F., Fischer, P.

{Zeitschrift f\"ur Anorganische und Allgemeine Chemie}, 627, pages: 2063-2069, 2001 (article)

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[BibTex]

[BibTex]


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Critical magnetic properties of disordered polycrystalline Fe75Fe25 and Cr70Fe30 alloys

Fischer, S. F., Kaul, S. N., Kronmüller, H.

{Physical Review B}, 65, 2001 (article)

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[BibTex]

[BibTex]


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From the electronic structure to the macroscopic behaviour: a multi-scale analysis of plasticity in intermetallic compounds

Fähnle, M., Kohlhammer, S., Bester, G.

In Influences of Interface and Dislocation Behavior on Microstructure Evolution, 652, pages: Y.4.5.1-Y.4.5.12, Materials Research Society Symposium Proceedings, MRS, Boston, Mass., 2001 (inproceedings)

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[BibTex]

[BibTex]


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Enhancement of the critical current density of YBa2Cu3O7-8-films by substracte irradiation

Leonhardt, S., Albrecht, J., Warthmann, R., Kronmüller, H.

In High-Tc Superconductors and Related Applications: Materials Science, Fundamental Properties, and Some Future Electronic Applications. Proceedings of the NATO Advanced Study Institute, 86, pages: 529-534, NATO Science Series 3. High Technology, Kluwer Academic Publishers, Albena, Bulgaria, 2001 (inproceedings)

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[BibTex]

[BibTex]


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Diffusion of 23Na and 35K in the eutectic melt Na0.32K0.69

Feinauer, A., Majer, G.

{Physical Review B}, 64, 2001 (article)

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[BibTex]

[BibTex]


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AMOC studies of positronium in fine MgO powder

van Waeyenberge, B., Dauwe, C., Stoll, H.

In Positron Annihilation. Proceedings of the 12th International Conference on Positron Annihilation, 363/365, pages: 401-403, Materials Science Forum, Trans Tech Publications Ltd., München, 2001 (inproceedings)

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[BibTex]

[BibTex]


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Influence of nanocrystallization on the evolution of domain patterns and the magnetoimpedance effect in amorphous Fe73.5Cu1Nb3Si13.5B9 ribbons

Guo, H. Q., Kronmüller, H., Dragon, T., Cheng, Z. H., Shen, B. G.

{Journal of Applied Physics}, 89(1):514-520, 2001 (article)

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[BibTex]

[BibTex]


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Ab-initio statistical mechanics for the phase diagram of NiAl including the effect of vacancies

Lechermann, F., Fähnle, M.

{Physica Status Solidi (B)}, 224, pages: R4-R6, 2001 (article)

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[BibTex]

[BibTex]


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Atomic defects and electronic structure of B2-FeAl, CoAl and NiAl

Fähnle, M., Meyer, B., Bester, G., Majer, J., Börnsen, N.

In Proceedings of DIMAT 2000, the Fifth International Conference on Diffusion in Materials, 194/199, pages: 279-285, Defect and Diffusion Forum, Scitec Publications Ltd., Paris, France, 2001 (inproceedings)

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[BibTex]

[BibTex]

1993


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Learning passive motor control strategies with genetic algorithms

Schaal, S., Sternad, D.

In 1992 Lectures in complex systems, pages: 913-918, (Editors: Nadel, L.;Stein, D.), Addison-Wesley, Redwood City, CA, 1993, clmc (inbook)

Abstract
This study investigates learning passive motor control strategies. Passive control is understood as control without active error correction; the movement is stabilized by particular properties of the controlling dynamics. We analyze the task of juggling a ball on a racket. An approximation to the optimal solution of the task is derived by means of optimization theory. In order to model the learning process, the problem is coded for a genetic algorithm in representations without sensory or with sensory information. For all representations the genetic algorithm is able to find passive control strategies, but learning speed and the quality of the outcome are significantly different. A comparison with data from human subjects shows that humans seem to apply yet different movement strategies to the ones proposed. For the feedback representation some implications arise for learning from demonstration.

am

link (url) [BibTex]

1993


link (url) [BibTex]


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A genetic algorithm for evolution from an ecological perspective

Sternad, D., Schaal, S.

In 1992 Lectures in Complex Systems, pages: 223-231, (Editors: Nadel, L.;Stein, D.), Addison-Wesley, Redwood City, CA, 1993, clmc (inbook)

Abstract
In the population model presented, an evolutionary dynamic is explored which is based on the operator characteristics of genetic algorithms. An essential modification in the genetic algorithms is the inclusion of a constraint in the mixing of the gene pool. The pairing for the crossover is governed by a selection principle based on a complementarity criterion derived from the theoretical tenet of perception-action (P-A) mutuality of ecological psychology. According to Swenson and Turvey [37] P-A mutuality underlies evolution and is an integral part of its thermodynamics. The present simulation tested the contribution of P-A-cycles in evolutionary dynamics. A numerical experiment compares the population's evolution with and without this intentional component. The effect is measured in the difference of the rate of energy dissipation, as well as in three operationalized aspects of complexity. The results support the predicted increase in the rate of energy dissipation, paralleled by an increase in the average heterogeneity of the population. Furthermore, the spatio-temporal evolution of the system is tested for the characteristic power-law relations of a nonlinear system poised in a critical state. The frequency distribution of consecutive increases in population size shows a significantly different exponent in functional relationship.

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[BibTex]

[BibTex]


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Roles for memory-based learning in robotics

Atkeson, C. G., Schaal, S.

In Proceedings of the Sixth International Symposium on Robotics Research, pages: 503-521, Hidden Valley, PA, 1993, clmc (inproceedings)

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[BibTex]

[BibTex]


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Design concurrent calculation: A CAD- and data-integrated approach

Schaal, S., Ehrlenspiel, K.

Journal of Engineering Design, 4, pages: 71-85, 1993, clmc (article)

Abstract
Besides functional regards, product design demands increasingly more for further reaching considerations. Quality alone cannot suffice anymore to compete in the market; design for manufacturability, for assembly, for recycling, etc., are well-known keywords. Those can largely be reduced to the necessity of design for costs. This paper focuses on a CAD-based approach to design concurrent calculation. It will discuss how, in the meantime well-established, tools like feature technology, knowledge-based systems, and relational databases can be blended into one coherent concept to achieve an entirely CAD- and data-integrated cost information tool. This system is able to extract data from the CAD-system, combine it with data about the company specific manufacturing environment, and subsequently autonomously evaluate manufacturability aspects and costs of the given CAD-model. Within minutes the designer gets quantitative in-formation about the major cost sources of his/her design. Additionally, some alternative methods for approximating manu-facturing times from empirical data, namely neural networks and local weighted regression, are introduced.

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[BibTex]

[BibTex]


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Open loop stable control strategies for robot juggling

Schaal, S., Atkeson, C. G.

In IEEE International Conference on Robotics and Automation, 3, pages: 913-918, Piscataway, NJ: IEEE, Georgia, Atlanta, May 2-6, 1993, clmc (inproceedings)

Abstract
In a series of case studies out of the field of dynamic manipulation (Mason, 1992), different principles for open loop stable control are introduced and analyzed. This investigation may provide some insight into how open loop control can serve as a useful foundation for closed loop control and, particularly, what to focus on in learning control. 

am

link (url) [BibTex]

link (url) [BibTex]