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2000


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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 (article)

Abstract
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.

am

link (url) [BibTex]

2000


link (url) [BibTex]


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Influence of substrate irradiation on critical density and microstructure in YBCO thin films

Leonhardt, S., Albrecht, J., Warthmann, R., Habermeier, H.-U., Kronmüller, H.

{Physica C}, 341-348, pages: 1979-1980, 2000 (article)

mms

[BibTex]

[BibTex]


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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., Uggerhoj, E., Vilakazi, Z. Z., Weisse, E.

{Nuclear Instruments and Methods in Physics Research B}, 164-165, pages: 27-43, 2000 (article)

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[BibTex]

[BibTex]


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Magnetoelastic effects in ultrathin epitaxial Ni films: An ab-initio study

Komelj, M., Fähnle, M.

{Journal of Magnetism and Magnetic Materials}, 222, pages: L 245-L 250, 2000 (article)

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[BibTex]

[BibTex]


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Evidence for near-grain boundary lattice rotations in an Fe(Si) alloy.

Rabkin, E., Semenov, V., Bischoff, E.

{Zeitschrift f\"ur Metallkunde}, 91, pages: 165-170, 2000 (article)

mms

[BibTex]

[BibTex]


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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, pages: 387-455, 2000 (article)

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[BibTex]

[BibTex]


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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, pages: 1-14, 2000 (article)

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[BibTex]

[BibTex]


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Melt-spun precipitation-hardened Sm2(Co,Cu,Fe,Zr)17 magnets with abnormal temperature dependence of coercivity

Goll, D., Kleinschroth, I., Sigle, W., Kronmüller, H.

{Applied Physics Letters}, 76, pages: 1054-1056, 2000 (article)

mms

[BibTex]

[BibTex]


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Hydrogen-induced phase transition of GdZn1-xMgx compounds

Reule, H., Hirscher, M.

{Journal of Alloys and Compounds}, 298, pages: 1-8, 2000 (article)

mms

[BibTex]

[BibTex]


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The influence of a finite bandwidth on the Verwey transition in magnetite

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

{Journal of Physics: Condensed Matter}, 12, pages: 5437-5452, 2000 (article)

mms

[BibTex]

[BibTex]


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Dynamics of a bouncing ball in human performance

Sternad, D., Duarte, M., Katsumata, H., Schaal, S.

Physical Review E, 63(011902):1-8, 2000, clmc (article)

Abstract
On the basis of a modified bouncing-ball model, we investigated whether human movements utilize principles of dynamic stability in their performance of a similar movement task. Stability analyses of the model provided predictions about conditions indicative of a dynamically stable period-one regime. In a series of experiments, human subjects bounced a ball rhythmically on a racket and displayed these conditions supporting that they attuned to and exploited the dynamic stability properties of the task.

am

link (url) [BibTex]

link (url) [BibTex]


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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 (article)

pi

[BibTex]

[BibTex]


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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 (article)

mms

[BibTex]

[BibTex]


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Symmetrical Tilt Grain boundaries in body-centred cubic transition metals: An ab-initio local-density-functional study

Ochs, T., Beck, O., Elsässer, C., Meyer, B.

{Philosophical Magazine A}, 80, pages: 351-372, 2000 (article)

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[BibTex]

[BibTex]


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The liquid ferromagnet Co80Pd20 and its critical exponent γ

Bührer, C., Beckmann, M., Fähnle, M., Maier, K.

{Journal of Magnetism and Magnetic Materials}, 212, pages: 211-224, 2000 (article)

mms

[BibTex]

[BibTex]


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Irreversible magnetization processes in a soft magnetic platelet

Hertel, R., Kronmüller, H.

{Physica B}, 275, pages: 1-4, 2000 (article)

mms

[BibTex]

[BibTex]


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Measurement of the Zener relaxation in high-purity FeCr single crystals

Hirscher, M., Brossmann, U., Henes, R.

{Materials Transactions, JIM}, 41, pages: 82-86, 2000 (article)

mms

[BibTex]

[BibTex]


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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 (article)

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[BibTex]


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Reactions in TiO2/Ti3Al and TiO2/TiAl bilayers: Application of target-factor analysis in auger electron spectroscopy

van Lier, J., Baretzky, B., Zalar, A., Mittemeijer, E. J.

{Surface and Interface Analysis}, 30, pages: 124-129, 2000 (article)

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[BibTex]

[BibTex]


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Ab-initio treatment of noncollinear spin systems within the atomic-sphere approximation and beyond

Grotheer, O., Ederer, C., Fähnle, M.

{Physical Review B}, 62, pages: 5601-5608, 2000 (article)

mms

[BibTex]

[BibTex]


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Is d-Al-Cu-Co a random tiling?

Zeger, G., Plachke, D., Carstanjen, H. D., Trebin, H. R.

{Materials Science and Engineering A}, 294, pages: 291-294, 2000 (article)

mms

[BibTex]

[BibTex]


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Nonlinear magnetoelastic coupling coefficients in Fe from an ab-initio calculation

Komelj, M., Fähnle, M.

{Journal of Magnetism and Magnetic Materials}, 220, pages: L 7-L 12, 2000 (article)

mms

[BibTex]

[BibTex]


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Current densities in low-angle grain boundaries of YBCO

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

{Physica C}, 341-348, pages: 1459-1460, 2000 (article)

mms

[BibTex]

[BibTex]


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The hydrogen desorption kinetics of Pd-coated LaNi5-type films

Cuevas, F., Hirscher, M.

{Journal of Alloys and Compounds}, 313, pages: 269-275, 2000 (article)

mms

[BibTex]

[BibTex]


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The structure of the trihydride GdH3

Ellner, M., Reule, H., Mittemeijer, E. J.

{Journal of Alloys and Compounds}, 309, pages: 127-131, 2000 (article)

mms

[BibTex]

[BibTex]


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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, pages: 223-228, 2000 (article)

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[BibTex]

[BibTex]


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Is the insulator-metal transition in perovskites associated with the bulk magnetic phase transition?

Baszynski, J., Walz, F., Tolinski, T.

{Sensors and Actuators}, 81, pages: 37-39, 2000 (article)

mms

[BibTex]

[BibTex]


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Correlated molecular-field theory of amorphous ferromagnets and the Gibbs free energy

Fähnle, M.

{Journal of Magnetism and Magnetic Materials}, 210, pages: L 1-L 4, 2000 (article)

mms

[BibTex]

[BibTex]


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Pinning mechanism of vortices at antiphase boundaries in YBa2Cu3O7-δ

Jooss, C., Warthmann, R., Kronmüller, H.

{Physical Review B}, 61, pages: 12433-12446, 2000 (article)

mms

[BibTex]

[BibTex]


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Spectral distribution of activation energies in YBa2Cu3O7-δthin films

Warthmann, R., Albrecht, J., Kronmüller, H., Joos, C.

{Physical Review B}, 62, pages: 15226-15229, 2000 (article)

mms

[BibTex]

[BibTex]


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Ab-initio calculation of the formation and migration energies for Monovacancies in Mg

Krimmel, H., Fähnle, M.

{Physical Review B}, 62, pages: 5489-5491, 2000 (article)

mms

[BibTex]

[BibTex]


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Controlled pushing of nanoparticles: modeling and experiments

Sitti, M., Hashimoto, H.

IEEE/ASME transactions on mechatronics, 5(2):199-211, IEEE, 2000 (article)

pi

[BibTex]

[BibTex]


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Investigation of strain softening of icosahedral AlPdMn single quasicrystals

Brunner, D., Plachke, D., Carstanjen, H. D.

{Physica Status Solidi (A)}, 177, pages: 203-217, 2000 (article)

mms

[BibTex]

[BibTex]


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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, pages: 5760-5764, 2000 (article)

mms

[BibTex]

[BibTex]


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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, pages: 536-543, 2000 (article)

mms

[BibTex]

[BibTex]


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Replacing muons by protons: polarized beam NMR

Schüth, J., Eversheim, P.-D., Herzog, P., Maier, K., Majer, G., Meyer, P., Roduner, E.

{Physica B}, 289-290, pages: 672-675, 2000 (article)

mms

[BibTex]

[BibTex]


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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, pages: 507-522, 2000 (article)

mms

[BibTex]

[BibTex]


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Theory of self-diffusion in alkali metals I. Results for monovacancies in Li, Na, and K

Schott, V., Fähnle, M., Madden, P. A.

{Journal of Physics: Condensed Matter}, 12, pages: 1171-1194, 2000 (article)

mms

[BibTex]

[BibTex]


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Theory of self-diffusion in alkali metals II. The influence of divacancies in Li

Schott, V., Fähnle, M., Madden, P. A.

{Journal of Physics: Condensed Matter}, 12, pages: 1195-1198, 2000 (article)

mms

[BibTex]

[BibTex]


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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, pages: 6019-6027, 2000 (article)

mms

[BibTex]

[BibTex]


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Vacuum arc deposition of Ti coatings

Straumal, B., Gust, W., Vershinin, N., Dimitriou, R., Rabkin, E.

{Surface and Coatings Technology}, 125, pages: 157-160, 2000 (article)

mms

[BibTex]

[BibTex]


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Internal friction in Ni-rich B2-NiAl

Brossmann, U., Hirscher, M., Schaible, D., Kronmüller, H.

{Scripta Materialia}, 42, pages: 1193-1197, 2000 (article)

mms

[BibTex]

[BibTex]


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Spectral distribution of activation energies in YBa2Cu3O7-δthin films

Warthmann, R., Albrecht, J., Kronmüller, H., Joos, C.

{Physical Review B}, 62, pages: 15226-15229, 2000 (article)

mms

[BibTex]

[BibTex]


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Pre-treatment of large area strips with the aid of a high power hall current accelerator

Vershinin, N., Dimitriou, R., Benmalek, M., Straumal, B., Gust, W., Vivas, J., Shulga, J.

{Surface and Coatings Technology}, 125, pages: 35-39, 2000 (article)

mms

[BibTex]

[BibTex]

1996


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A Kendama learning robot based on bi-directional theory

Miyamoto, H., Schaal, S., Gandolfo, F., Koike, Y., Osu, R., Nakano, E., Wada, Y., Kawato, M.

Neural Networks, 9(8):1281-1302, 1996, clmc (article)

Abstract
A general theory of movement-pattern perception based on bi-directional theory for sensory-motor integration can be used for motion capture and learning by watching in robotics. We demonstrate our methods using the game of Kendama, executed by the SARCOS Dextrous Slave Arm, which has a very similar kinematic structure to the human arm. Three ingredients have to be integrated for the successful execution of this task. The ingredients are (1) to extract via-points from a human movement trajectory using a forward-inverse relaxation model, (2) to treat via-points as a control variable while reconstructing the desired trajectory from all the via-points, and (3) to modify the via-points for successful execution. In order to test the validity of the via-point representation, we utilized a numerical model of the SARCOS arm, and examined the behavior of the system under several conditions.

am

link (url) [BibTex]

1996


link (url) [BibTex]


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One-handed juggling: A dynamical approach to a rhythmic movement task

Schaal, S., Sternad, D., Atkeson, C. G.

Journal of Motor Behavior, 28(2):165-183, 1996, clmc (article)

Abstract
The skill of rhythmic juggling a ball on a racket is investigated from the viewpoint of nonlinear dynamics. The difference equations that model the dynamical system are analyzed by means of local and non-local stability analyses. These analyses yield that the task dynamics offer an economical juggling pattern which is stable even for open-loop actuator motion. For this pattern, two types of pre dictions are extracted: (i) Stable periodic bouncing is sufficiently characterized by a negative acceleration of the racket at the moment of impact with the ball; (ii) A nonlinear scaling relation maps different juggling trajectories onto one topologically equivalent dynamical system. The relevance of these results for the human control of action was evaluated in an experiment where subjects performed a comparable task of juggling a ball on a paddle. Task manipulations involved different juggling heights and gravity conditions of the ball. The predictions were confirmed: (i) For stable rhythmic performance the paddle's acceleration at impact is negative and fluctuations of the impact acceleration follow predictions from global stability analysis; (ii) For each subject, the realizations of juggling for the different experimental conditions are related by the scaling relation. These results allow the conclusion that for the given task, humans reliably exploit the stable solutions inherent to the dynamics of the task and do not overrule these dynamics by other control mechanisms. The dynamical scaling serves as an efficient principle to generate different movement realizations from only a few parameter changes and is discussed as a dynamical formalization of the principle of motor equivalence.

am

link (url) [BibTex]

link (url) [BibTex]


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In vivo diabetic wound healing with nanofibrous scaffolds modified with gentamicin and recombinant human epidermal growth factor

Dwivedi, C., Pandey, I., Pandey, H., Patil, S., Mishra, S. B., Pandey, A. C., Zamboni, P., Ramteke, P. W., Singh, A. V.

Journal of Biomedical Materials Research Part A, 106(3):641-651, March (article)

Abstract
Abstract Diabetic wounds are susceptible to microbial infection. The treatment of these wounds requires a higher payload of growth factors. With this in mind, the strategy for this study was to utilize a novel payload comprising of Eudragit RL/RS 100 nanofibers carrying the bacterial inhibitor gentamicin sulfate (GS) in concert with recombinant human epidermal growth factor (rhEGF); an accelerator of wound healing. GS containing Eudragit was electrospun to yield nanofiber scaffolds, which were further modified by covalent immobilization of rhEGF to their surface. This novel fabricated nanoscaffold was characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, and X‐ray diffraction. The thermal behavior of the nanoscaffold was determined using thermogravimetric analysis and differential scanning calorimetry. In the in vitro antibacterial assays, the nanoscaffolds exhibited comparable antibacterial activity to pure gentemicin powder. In vivo work using female C57/BL6 mice, the nanoscaffolds induced faster wound healing activity in dorsal wounds compared to the control. The paradigm in this study presents a robust in vivo model to enhance the applicability of drug delivery systems in wound healing applications. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 641–651, 2018.

pi

link (url) DOI [BibTex]


link (url) DOI [BibTex]


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Classified Regression for Bayesian Optimization: Robot Learning with Unknown Penalties

Marco, A., Baumann, D., Hennig, P., Trimpe, S.

Submitted to Journal (under review) (article)

Abstract
Learning robot controllers by minimizing a black-box objective cost using Bayesian optimization (BO) can be time-consuming and challenging. It is very often the case that some roll-outs result in failure behaviors, causing premature experiment detention. In such cases, the designer is forced to decide on heuristic cost penalties because the acquired data is often scarce, or not comparable with that of the stable policies. To overcome this, we propose a Bayesian model that captures exactly what we know about the cost of unstable controllers prior to data collection: Nothing, except that it should be a somewhat large number. The resulting Bayesian model, approximated with a Gaussian process, predicts high cost values in regions where failures are likely to occur. In this way, the model guides the BO exploration toward regions of stability. We demonstrate the benefits of the proposed model in several illustrative and statistical synthetic benchmarks, and also in experiments on a real robotic platform. In addition, we propose and experimentally validate a new BO method to account for unknown constraints. Such method is an extension of Max-Value Entropy Search, a recent information-theoretic method, to solve unconstrained global optimization problems.

PDF link (url) [BibTex]