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2022

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Autonomous Motion Conference Paper Fast and efficient incremental learning for high-dimensional movement systems Vijayakumar, S., Schaal, S. In International Conference on Robotics and Automation (ICRA2000), San Francisco, April 2000, 2000, clmc
We introduce a new algorithm, Locally Weighted Projection Regression (LWPR), for incremental real-time learning of nonlinear functions, as particularly useful for problems of autonomous real-time robot control that re-quires internal models of dynamics, kinematics, or other functions. At its core, LWPR uses locally linear models, spanned by a small number of univariate regressions in selected directions in input space, to achieve piecewise linear function approximation. The most outstanding properties of LWPR are that it i) learns rapidly with second order learning methods based on incremental training, ii) uses statistically sound stochastic cross validation to learn iii) adjusts its local weighting kernels based on only local information to avoid interference problems, iv) has a computational complexity that is linear in the number of inputs, and v) can deal with a large number ofâ??possibly redundant and/or irrelevantâ??inputs, as shown in evaluations with up to 50 dimensional data sets for learning the inverse dynamics of an anthropomorphic robot arm. To our knowledge, this is the first incremental neural network learning method to combine all these properties and that is well suited for complex on-line learning problems in robotics.
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Autonomous Motion Conference Paper Fast learning of biomimetic oculomotor control with nonparametric regression networks Shibata, T., Schaal, S. In International Conference on Robotics and Automation (ICRA2000), 3847-3854, San Francisco, April 2000, 2000, clmc
Accurate oculomotor control is one of the essential pre-requisites of successful visuomotor coordination. Given the variable nonlinearities of the geometry of binocular vision as well as the possible nonlinearities of the oculomotor plant, it is desirable to accomplish accurate oculomotor control through learning approaches. In this paper, we investigate learning control for a biomimetic active vision system mounted on a humanoid robot. By combining a biologically inspired cerebellar learning scheme with a state-of-the-art statistical learning network, our robot system is able to acquire high performance visual stabilization reflexes after about 40 seconds of learning despite significant nonlinearities and processing delays in the system.
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Autonomous Motion Conference Paper Humanoid Robot DB Kotosaka, S., Shibata, T., Schaal, S. In Proceedings of the International Conference on Machine Automation (ICMA2000), 21-26, 2000, clmc BibTeX
Autonomous Motion Article Interaction of rhythmic and discrete pattern generators in single joint movements Sternad, D., Dean, W. J., Schaal, S. Human Movement Science, 19(4):627-665, 2000, clmc
The study investigates a single-joint movement task that combines a translatory and cyclic component with the objective to investigate the interaction of discrete and rhythmic movement elements. Participants performed an elbow movement in the horizontal plane, oscillating at a prescribed frequency around one target and shifting to a second target upon a trigger signal, without stopping the oscillation. Analyses focused on extracting the mutual influences of the rhythmic and the discrete component of the task. Major findings are: (1) The onset of the discrete movement was confined to a limited phase window in the rhythmic cycle. (2) Its duration was influenced by the period of oscillation. (3) The rhythmic oscillation was "perturbed" by the discrete movement as indicated by phase resetting. On the basis of these results we propose a model for the coordination of discrete and rhythmic actions (K. Matsuoka, Sustained oscillations generated by mutually inhibiting neurons with adaptations, Biological Cybernetics 52 (1985) 367-376; Mechanisms of frequency and pattern control in the neural rhythm generators, Biological Cybernetics 56 (1987) 345-353). For rhythmic movements an oscillatory pattern generator is developed following models of half-center oscillations (D. Bullock, S. Grossberg, The VITE model: a neural command circuit for generating arm and articulated trajectories, in: J.A.S. Kelso, A.J. Mandel, M. F. Shlesinger (Eds.), Dynamic Patterns in Complex Systems. World Scientific. Singapore. 1988. pp. 305-326). For discrete movements a point attractor dynamics is developed close to the VITE model For each joint degree of freedom both pattern generators co-exist but exert mutual inhibition onto each other. The suggested modeling framework provides a unified account for both discrete and rhythmic movements on the basis of neuronal circuitry. Simulation results demonstrated that the effects observed in human performance can be replicated using the two pattern generators with a mutually inhibiting coupling.
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Autonomous Motion Conference Paper Inverse kinematics for humanoid robots Tevatia, G., Schaal, S. In International Conference on Robotics and Automation (ICRA2000), 294-299, San Fransisco, April 24-28, 2000, 2000, clmc
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 methods of resolved motion rate control (RMRC) that employ optimization criteria to resolve kinematic redundancies. In particular we focus on two established techniques, the pseudo inverse with explicit optimization and the extended Jacobian method. We prove that the extended Jacobian method includes pseudo-inverse methods as a special solution. In terms of computational complexity, however, pseudo-inverse and extended Jacobian differ significantly in favor of pseudo-inverse methods. Employing numerical estimation techniques, we introduce a computationally efficient version of the extended Jacobian with performance comparable to the original version . Our results are illustrated in simulation studies with a multiple degree-of-freedom robot, and were tested on a 30 degree-of-freedom robot. 
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Physical Intelligence Article Investigation of Virtual Reality Interface for AFM-based Nano Manipulation Horiguchi, S., Sitti, M., Hashimoto, H. IEEJ Transactions on Electronics, Information and Systems, 120(12):1948-1956, The Institute of Electrical Engineers of Japan, 2000 BibTeX
Autonomous Motion Conference Paper Locally weighted projection regression: An O(n) algorithm for incremental real time learning in high dimensional spaces Vijayakumar, S., Schaal, S. In Proceedings of the Seventeenth International Conference on Machine Learning (ICML 2000), 1:288-293, Stanford, CA, 2000, clmc
Locally weighted projection regression is a new algorithm that achieves nonlinear function approximation in high dimensional spaces with redundant and irrelevant input dimensions. At its core, it uses locally linear models, spanned by a small number of univariate regressions in selected directions in input space. This paper evaluates different methods of projection regression and derives a nonlinear function approximator based on them. This nonparametric local learning system i) learns rapidly with second order learning methods based on incremental training, ii) uses statistically sound stochastic cross validation to learn iii) adjusts its weighting kernels based on local information only, iv) has a computational complexity that is linear in the number of inputs, and v) can deal with a large number of - possibly redundant - inputs, as shown in evaluations with up to 50 dimensional data sets. To our knowledge, this is the first truly incremental spatially localized learning method to combine all these properties.
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Physical Intelligence Article Macro to Nano Tele-Manipulation Towards Nanoelectromec hanical Systems Sitti, M., Hashimoto, H. Journal of Robotics and Mechatronics, 12(3):209-217, FUJI TECHNOLOGY PRESS LTD., 2000 BibTeX
Autonomous Motion Conference Paper On-line learning for humanoid robot systems Conradt, J., Tevatia, G., Vijayakumar, S., Schaal, S. In Proceedings of the Seventeenth International Conference on Machine Learning (ICML 2000), 1:191-198, Stanford, CA, 2000, clmc
Humanoid robots are high-dimensional movement systems for which analytical system identification and control methods are insufficient due to unknown nonlinearities in the system structure. As a way out, supervised learning methods can be employed to create model-based nonlinear controllers which use functions in the control loop that are estimated by learning algorithms. However, internal models for humanoid systems are rather high-dimensional such that conventional learning algorithms would suffer from slow learning speed, catastrophic interference, and the curse of dimensionality. In this paper we explore a new statistical learning algorithm, locally weighted projection regression (LWPR), for learning internal models in real-time. LWPR is a nonparametric spatially localized learning system that employs the less familiar technique of partial least squares regression to represent functional relationships in a piecewise linear fashion. The algorithm can work successfully in very high dimensional spaces and detect irrelevant and redundant inputs while only requiring a computational complexity that is linear in the number of input dimensions. We demonstrate the application of the algorithm in learning two classical internal models of robot control, the inverse kinematics and the inverse dynamics of an actual seven degree-of-freedom anthropomorphic robot arm. For both examples, LWPR can achieve excellent real-time learning results from less than one hour of actual training data.
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Theory of Inhomogeneous Condensed Matter Article Oxygen-related muon species in crystalline silicon Schefzik, M., Schimmele, L., Seeger, A., Herlach, D., Kormann, O., Major, J., Röck, A. Physica B, 289-290:521-524, 2000 BibTeX
Micro, Nano, and Molecular Systems Article Phenomenological damping in optical response tensors Buckingham, A., Fischer, P. PHYSICAL REVIEW A, 61(3), 2000
Although perturbation theory applied to the optical response of a molecule or material system is only strictly valid far from resonances, it is often applied to ``near-resonance{''} conditions by means of complex energies incorporating damping. Inconsistent signs of the damping in optical response tensors have appeared in the recent literature, as have errors in the treatment of the perturbation by a static held. The ``equal-sign{''} convention used in a recent publication yields an unphysical material response, and Koroteev's intimation that linear electro-optical circular dichroism may exist in an optically active liquid under resonance conditions is also flawed. We show that the isotropic part of the Pockels tensor vanishes.
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Theory of Inhomogeneous Condensed Matter Article Radio-frequency \muSR investigations on paramagnetic muonium centres in crystalline silicon Kormann, O., Major, J., Reid, I. D., Röck, A., Schefzik, M., Schimmele, L., Seeger, A., Herlach, D. Physica B, 289-290:530-533, 2000 BibTeX
Autonomous Motion Conference Paper Real-time robot learning with locally weighted statistical learning Schaal, S., Atkeson, C. G., Vijayakumar, S. In International Conference on Robotics and Automation (ICRA2000), San Francisco, April 2000, 2000, clmc
Locally weighted learning (LWL) is a class of statistical learning techniques that provides useful representations and training algorithms for learning about complex phenomena during autonomous adaptive control of robotic systems. This paper introduces several LWL algorithms that have been tested successfully in real-time learning of complex robot tasks. We discuss two major classes of LWL, memory-based LWL and purely incremental LWL that does not need to remember any data explicitly. In contrast to the traditional beliefs that LWL methods cannot work well in high-dimensional spaces, we provide new algorithms that have been tested in up to 50 dimensional learning problems. The applicability of our LWL algorithms is demonstrated in various robot learning examples, including the learning of devil-sticking, pole-balancing of a humanoid robot arm, and inverse-dynamics learning for a seven degree-of-freedom robot.
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Theory of Inhomogeneous Condensed Matter Ph.D. Thesis Selbst- und Fremddiffusion in amorphem Si28C36N36 und Si3N4 Matics, S. Universität Stuttgart, Stuttgart, 2000 URL BibTeX
Theory of Inhomogeneous Condensed Matter Article The interaction of positive muons with photogenerated charge carriers in crystalline silicon Scheuermann, R., Major, J., Seeger, A., Schimmele, L., Schmidl, J., Herlach, D. Physica B, 289-290:534-537, 2000 BibTeX
Micro, Nano, and Molecular Systems Article Three-wave mixing in chiral liquids Fischer, P., Wiersma, D., Righini, R., Champagne, B., Buckingham, A. PHYSICAL REVIEW LETTERS, 85(20):4253-4256, 2000
Second-order nonlinear optical frequency conversion in isotropic systems is only dipole allowed for sum- and difference-frequency generation in chiral media. We develop a single-center chiral model of the three-wave mixing (sum:frequency generation) nonlinearity and estimate its magnitude. We also report results from ab initio calculations and from three- and four-wave mixing experiments in support of the theoretical estimates. We show that the second-order susceptibility in chiral liquids is much smaller than previously thought.
DOI BibTeX
Physical Intelligence Article Two-dimensional fine particle positioning under an optical microscope using a piezoresistive cantilever as a manipulator Sitti, M., Hashimoto, H. journal of Micromechatronics, 1(1):25-48, Brill, 2000 BibTeX
Physical Intelligence Conference Paper Wing transmission for a micromechanical flying insect Fearing, R. S., Chiang, K. H., Dickinson, M. H., Pick, D., Sitti, M., Yan, J. In Robotics and Automation, 2000. Proceedings. ICRA’00. IEEE International Conference on, 2:1509-1516, 2000 BibTeX
Modern Magnetic Systems Article A review of the magnetic relaxation and its application to the study of atomic defects in α-iron and its diuluted alloys Blythe, H. J., Kronmüller, H., Seeger, A., Walz, F. {Physica Status Solidi (A)}, 181:233-345, 2000 BibTeX
Modern Magnetic Systems Master Thesis Ab-initio Berechnung von Spinwellenspektren in verschiedenen intermetallischen Verbindungen - Implementation einer full-spin LMTO-Methode. Ederer, C. Universität Stuttgart, Stuttgart, 2000 BibTeX
Modern Magnetic Systems Article Ab-initio calculation of the formation and migration energies for Monovacancies in Mg Krimmel, H., Fähnle, M. {Physical Review B}, 62:5489-5491, 2000 BibTeX
Modern Magnetic Systems Article Ab-initio statistical mechanics for alloy phase diagrams and ordering phenomena including the effect of vacancies Lechermann, F., Fähnle, M. {Physical Review B}, 63, 2000 BibTeX
Modern Magnetic Systems Article Ab-initio treatment of noncollinear spin systems within the atomic-sphere approximation and beyond Grotheer, O., Ederer, C., Fähnle, M. {Physical Review B}, 62:5601-5608, 2000 BibTeX
Modern Magnetic Systems Book Chapter Age-momentum correlation (AMOC) Stoll, H. In Construction and Use of an Intense Positron Source at new Linac Facilities in Germany, FZR-295:44-49, Wissenschaftlich-Technische Berichte, 2000 BibTeX
Modern Magnetic Systems Article Analysis of the electronic structure of intermetallic compounds and application to structural defects in B2 phases Börnsen, N., Meyer, B., Bester, G., Fähnle, M. {Journal of Alloys and Compounds}, 308:1-14, 2000 BibTeX
Modern Magnetic Systems Article Anisotropic flux pinning in thin YBCO-films by substrate modifications Leonhardt, S., Warthmann, R., Albrecht, J., Jooss, C., Kronmüller, H., Haage, T., Zegenhagen, J., Habermeier, H. {Physica C}, 332:214-218, 2000 BibTeX
Modern Magnetic Systems Article Channeling of high-energy particles in bent crystals - experiments at the CERN SPS Baurichter, A., Biino, C., Clement, M., Doble, N., Elsener, K., Fidecaro, G., Freund, A., Gatignon, L., Grafström, P., Gyr, M., Hage-Ali, M., Herr, W., Keppler, P., Kirsebom, K., Klem, J., Major, J., Medenwaldt, R., Mikkelsen, U., Moller, S. P., Siffert, P., et al. {Nuclear Instruments and Methods in Physics Research B}, 164-165:27-43, 2000 BibTeX
Modern Magnetic Systems Article Charge transport mechanisms in single crystalline yttrium iron garnet as resolved by magnetic relaxation Walz, F., Torres, L., Iñiguez, J., Kronmüller, H. {Physica Status Solidi (A)}, 180:507-522, 2000 BibTeX
Modern Magnetic Systems Article Comment on "Point Defect Behaviour in High Temperature Region in the B 2-Type Intermetallic Compound FeAl" by Kogachi, M., Haraguchi, T. and S.M. Kim Fähnle, M., Meyer, B., Bester, G. {Intermetallics}, 7:1307-1308, 2000 BibTeX
Modern Magnetic Systems Article Computational micromagnetism of magnetic structures and magnetization processes in small particles Kronmüller, H., Hertel, R. {Journal of Magnetism and Magnetic Materials}, 215-216:11-17, 2000 BibTeX
Modern Magnetic Systems Article Correlated molecular-field theory of amorphous ferromagnets and the Gibbs free energy Fähnle, M. {Journal of Magnetism and Magnetic Materials}, 210:L 1-L 4, 2000 BibTeX
Modern Magnetic Systems Article Corrosion behaviour of the protective and decorative TiN coatings on large area steel strips Vershinin, N., Filonov, K., Straumal, B., Gust, W., Wiener, I., Rabkin, E., Kazakevich, A. {Surface and Coatings Technology}, 125:229-232, 2000 BibTeX
Modern Magnetic Systems Article Corrosion resistance of the vacuum arc deposited Ti, TiN and TiO2 coatings on large area glass substrates Vershinin, N., Filonov, K., Straumal, B., Gust, W., Dimitriou, R., Kovalev, A., Camacho, J. {Surface and Coatings Technology}, 125:223-228, 2000 BibTeX
Modern Magnetic Systems Book Chapter Critical behaviour of V2H in a defective near-surface skin layer Trenkler, J., Moss, S. C., Reichert, H., Paniago, R., Gebhardt, U., Carstanjen, H. D., Metzger, T. H., Peisl, J. In Exploration of Subsurface Phenomena by Particle Scattering, 155-164, International Advanced Studies Institute IASI Press, North East/MD, 2000 BibTeX
Modern Magnetic Systems Article Current densities in low-angle grain boundaries of YBCO Albrecht, J., Warthmann, R., Leonhardt, S., Kronmüller, H. {Physica C}, 341-348:1459-1460, 2000 BibTeX
Modern Magnetic Systems Article Decay kinetics of nonequilibrium Al-Si solid solutions Sluchanko, N. E., Glushkov, V. V., Demishev, S. V., Kondrin, M. V., Ischenko, T. V., Gust, W., Brazhkin, V. V., Straumal, B. B., Bruynseraede, Y., Moshchalkov, V. V. {Physical Review B}, 61:6019-6027, 2000 BibTeX
Modern Magnetic Systems Article Deflection of 32.8 TeV/c fully stripped Pb ions by means of a bent Si crystal Biino, C., Clement, M., Doble, N., Elsener, K., Gatignon, L., Grafström, P., Herr, W., Keppler, P., Major, J., Mikkelsen, U., Taratin, A., Velasco, M. {Nuclear Instruments and Methods in Physics Research B}, 160:536-543, 2000 BibTeX
Modern Magnetic Systems Ph.D. Thesis Diffusion von Wasserstoff in Lavesphasen / Diffusion von Wasserstoff in heterogenen Systemen. Herrmann, A. Universität Stuttgart, Stuttgart, 2000 BibTeX
Modern Magnetic Systems Article Electron focusing in metals and semimetals Heil, J., Böhm, A., Gröger, A., Primke, M., Wyder, P., Keppler, P., Major, J., Bender, H., Schönherr, E., Wendel, H., Wolf, B., Würz, U., Grill, W., Herrenberger, S., Knauth, S., Lenzner, J. {Physics Reports}, 323:387-455, 2000 BibTeX
Modern Magnetic Systems Article Evidence for near-grain boundary lattice rotations in an Fe(Si) alloy. Rabkin, E., Semenov, V., Bischoff, E. {Zeitschrift f\"ur Metallkunde}, 91:165-170, 2000 BibTeX
Modern Magnetic Systems Conference Paper Evolution of microstructure and microchemistry in the high-temperature Sm(Co, Fe, Cu, Zr)z magnets Zhang, Y. W., Hadjipanayis, G. C., Goll, D., Kronmüller, H., Chen, C., Nelson, C., Krishnan, K. In Proceedings of the 16th International Workshop on Rare-Earth Magnets and Their Applications, 169-178, Sendai, Japan, 2000 BibTeX
Modern Magnetic Systems Conference Paper Experimental and theoretical study of the Verwey transition in magnetite Brabers, V. A. M., Brabers, J. H. V. J., Walz, F., Kronmüller, H. In Proceedings 8th International Conference on Ferrites, 123-125, Japan Society of Powder and Powder Metallurgy, 2000 BibTeX
Modern Magnetic Systems Article Formation and evolution of the transverse anisotropy with nanocrystallization in amorphous Fe73.5CuNb3Si13.5B9 ribbons Guo, H. Q., Kronmüller, H., Dragon, T., Cheng, Z. H., Shen, B. G. {Physical Review}, 62:5760-5764, 2000 BibTeX
Modern Magnetic Systems Conference Paper Fundamental investigations and industrial applications of magnetostriction Hirscher, M., Fischer, S. F., Reininger, T. In Modern Trends in Magnetostriction Study and Application. Proceedings of the NATO Advanced Study Institute on Modern Trends in Magnetostriction, 5:307-329, NATO Science Series: II: Mathematics, Physics and Chemistry, Kluwer Academic Publishers, Kyiv, Ukraine, 2000 BibTeX
Modern Magnetic Systems Conference Paper High-performance nanocrystalline PrFeB-based bonded permanent magnets Goll, D., Kleinschroth, I., Kronmüller, H. In Proceedings of the 16th International Workshop on Rare-Earth Magnets and Their Applications, 641-650, Japan Institute of Metals, 2000 BibTeX
Modern Magnetic Systems Article High-performance permanent magnets Goll, D., Kronmüller, H. {Naturwissenschaften}, 87:423-438, 2000 BibTeX
Modern Magnetic Systems Article Hydrogen-induced phase transition of GdZn1-xMgx compounds Reule, H., Hirscher, M. {Journal of Alloys and Compounds}, 298:1-8, 2000 BibTeX
Modern Magnetic Systems Article Influcence of vortex-vortex interaction on critical currents across low-angle grain boundaries in YBa2Cu3O7-δ Albrecht, J., Leonhardt, S., Kronmüller, H. {Physical Review B}, 63, 2000 BibTeX
Modern Magnetic Systems Article Influence of substrate irradiation on critical density and microstructure in YBCO thin films Leonhardt, S., Albrecht, J., Warthmann, R., Habermeier, H., Kronmüller, H. {Physica C}, 341-348:1979-1980, 2000 BibTeX
Modern Magnetic Systems Article Interface-structure studies by atomic-resolution electron microscopy, order-disorder phenomena, and atomic diffusion in gas-phase-synthesized nanocrystalline solids Schaefer, H., Reimann, K., Straub, W., Phillipp, F., Tanimoto, H., Brossmann, U., Würschum, R. {Materials Science and Engineering A}, 286:24-33, 2000 BibTeX