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2010


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Using an Infinite Von Mises-Fisher Mixture Model to Cluster Treatment Beam Directions in External Radiation Therapy

Bangert, M., Hennig, P., Oelfke, U.

In pages: 746-751 , (Editors: Draghici, S. , T.M. Khoshgoftaar, V. Palade, W. Pedrycz, M.A. Wani, X. Zhu), IEEE, Piscataway, NJ, USA, Ninth International Conference on Machine Learning and Applications (ICMLA), December 2010 (inproceedings)

Abstract
We present a method for fully automated selection of treatment beam ensembles for external radiation therapy. We reformulate the beam angle selection problem as a clustering problem of locally ideal beam orientations distributed on the unit sphere. For this purpose we construct an infinite mixture of von Mises-Fisher distributions, which is suited in general for density estimation from data on the D-dimensional sphere. Using a nonparametric Dirichlet process prior, our model infers probability distributions over both the number of clusters and their parameter values. We describe an efficient Markov chain Monte Carlo inference algorithm for posterior inference from experimental data in this model. The performance of the suggested beam angle selection framework is illustrated for one intra-cranial, pancreas, and prostate case each. The infinite von Mises-Fisher mixture model (iMFMM) creates between 18 and 32 clusters, depending on the patient anatomy. This suggests to use the iMFMM directly for beam ensemble selection in robotic radio surgery, or to generate low-dimensional input for both subsequent optimization of trajectories for arc therapy and beam ensemble selection for conventional radiation therapy.

ei pn

Web DOI [BibTex]

2010


Web DOI [BibTex]


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Coherent Inference on Optimal Play in Game Trees

Hennig, P., Stern, D., Graepel, T.

In JMLR Workshop and Conference Proceedings Volume 9: AISTATS 2010, pages: 326-333, (Editors: Teh, Y.W. , M. Titterington ), JMLR, Cambridge, MA, USA, Thirteenth International Conference on Artificial Intelligence and Statistics, May 2010 (inproceedings)

Abstract
Round-based games are an instance of discrete planning problems. Some of the best contemporary game tree search algorithms use random roll-outs as data. Relying on a good policy, they learn on-policy values by propagating information upwards in the tree, but not between sibling nodes. Here, we present a generative model and a corresponding approximate message passing scheme for inference on the optimal, off-policy value of nodes in smooth AND/OR trees, given random roll-outs. The crucial insight is that the distribution of values in game trees is not completely arbitrary. We define a generative model of the on-policy values using a latent score for each state, representing the value under the random roll-out policy. Inference on the values under the optimal policy separates into an inductive, pre-data step and a deductive, post-data part. Both can be solved approximately with Expectation Propagation, allowing off-policy value inference for any node in the (exponentially big) tree in linear time.

ei pn

PDF Web [BibTex]

PDF Web [BibTex]


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Dzyaloshinskii-Moriya interactions in systems with fabrication induced strain gradients: ab-initio study

Beck, P., Fähnle, M

{Journal of Magnetism and Magnetic Materials}, 322, pages: 3701-3703, 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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On the nature of displacement bursts during nanoindentation of ultrathin Ni films on sapphire

Rabkin, E., Deuschle, J. K., Baretzky, B.

{Acta Materialia}, 58, pages: 1589-1598, 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Nanospheres generate out-of-plane magnetization

Amaladass, E., Ludescher, B., Schütz, G., Tyliszczak, T., Lee, M., Eimüller, T.

{Journal of Applied Physics}, 107, 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Absence of element specific ferromagnetism in Co doped ZnO investigated by soft X-ray resonant reflectivity

Goering, E., Brück, S., Tietze, T., Jakob, G., Gacic, M., Adrian, H.

In 200, Glasgow, Scotland, 2010 (inproceedings)

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DOI [BibTex]

DOI [BibTex]


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Probing the local magnetization dynamics in large systems with spatial inhomogeneity

Li, J, Lee, M.-S., Amaladass, E., He, W., Eimüller, T.

In 200, Glasgow, Scotland, 2010 (inproceedings)

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DOI [BibTex]

DOI [BibTex]


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Temperature dependence of the magnetic properties of L10-FePt nanostructures and films

Bublat, T., Goll, D.

{Journal of Applied Physics}, 108(11), 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Wetting of grain boundaries in Al by the solid Al3Mg2 phase

Straumal, B. B., Baretzky, B., Kogtenkova, O. A., Straumal, A. B., Sidorenko, A. S.

In 45, pages: 2057-2061, Athens, Greek, 2010 (inproceedings)

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DOI [BibTex]

DOI [BibTex]


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Damping of near-adiabatic magnetization dynamics by excitations of electron-hole pairs

Seib, J., Steiauf, D., Fähnle, M.

In 200, Karlsruhe, Germany, 2010 (inproceedings)

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DOI [BibTex]

DOI [BibTex]


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Magnetic properties of Fe nanoclusters on Cu(111) studied with X-ray magnetic circular dichroism

Fauth, K., Ballentine, G., Praetorius, C., Kleibert, A., Wilken, N., Voitkans, A., Meiwes-Broer, K.-H.

{Physica Status Solidi B}, 247(5):1170-1179, 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Statics and dynamics of simple fluids on chemically patterned substrates

Dörfler, F.

Universität Stuttgart, Stuttgart, Germany, 2010 (phdthesis)

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link (url) [BibTex]

link (url) [BibTex]


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Nanoscale imaging using deep ultraviolet digital holographic microscopy

Faridian, A., Hopp, D., Pedrini, G., Eigenthaler, U., Hirscher, M., Osten, W.

{Optics Express}, 18(13):14159-14164, 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Metal-organic frameworks for hydrogen storage

Hirscher, M., Panella, B., Schmitz, B.

{Microporous and Mesoporous Materials}, 129, pages: 335-339, 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Samarium-cobalt 2:17 magnets: analysis of the coercive field of Sm2(CoFeCuZr)17 high-temperature permanent magnets

Goll, D., Stadelmaier, H. H., Kronmüller, H.

{Scripta Materialia}, 63, pages: 243-245, 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Low-temperature growth of silicon nanotubes and nanowires on amorphous substrates

Mbenkum, B. N., Schneider, A. S., Schütz, G., Xu, C., Richter, G., van Aken, P. A., Majer, G., Spatz, J. P.

{ACS Nano}, 4(4):1805-1812, 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Physisorption in porous materials

Hirscher, M., Panella, B.

In Handbook of Hydrogen Storage, pages: 39-62, WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2010 (incollection)

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[BibTex]

[BibTex]


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Formation and mobility of protonic charge carriers in methyl sulfonic acid-water mixtures: A model for sulfonic acid based ionomers at low degree of hydration

Telfah, A., Majer, G., Kreuer, K. D., Schuster, M., Maier, J.

{Solid State Ionics}, 181, pages: 461-465, 2010 (article)

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[BibTex]

[BibTex]


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Magnetization reversal of Fe/Gd multilayers on self-assembled arrays of nanospheres

Amaladass, E., Eimüller, T., Ludescher, B., Tyliszczak, T., Schütz, G.

In 200, Glasgow, Scotland, 2010 (inproceedings)

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DOI [BibTex]

DOI [BibTex]


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Continuous photobleaching to study the growth modes of focal adhesions

de Beer, A. G. F., Majer, G., Roke, S., Spatz, J. P.

{Journal of Adhesion Science and Technology}, 24, pages: 2323-2334, 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Magnetic antivortex-core reversal by circular-rotational spin currents

Kamionka, T., Martens, M., Chou, K. W., Curcic, M., Drews, A., Schütz, G., Tyliszczak, T., Stoll, H., Van Waeyenberge, B., Meier, G.

{Physical Review Letters}, 105, 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Extension of Yafet\textquotesingles theory of spin relaxation to ferromagnets

Steiauf, D., Illg, C., Fähnle, M.

{Journal of Magnetism and Magnetic Materials}, 322, pages: L5-L7, 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Lateral transport of thermal capillary waves

Smith, T. H. R., Vasilyev, O., Maciolek, A., Schmidt, M.

{Europhysics Letters}, 89(1), 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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The formation and propagation of flux avalanches in tailored MgB2 films

Treiber, S., Albrecht, J.

{New Journal of Physics}, 12, 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Direct imaging of current induced magnetic vortex gyration in an asymmetric potential well

Bisig, A., Rhensius, J., Kammerer, M., Curcic, M., Stoll, H., Schütz, G., Van Waeyenberge, B., Chou, K. W., Tyliszczak, T., Heyderman, L. J., Krzyk, S., von Bieren, A., Kläui, M.

{Applied Physics Letters}, 96, 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Induced magnetism of carbon atoms at the graphene/Ni(111) interface

Weser, M., Rehder, Y., Horn, K., Sicot, M., Fonin, M., Preobrajenski, A. B., Voloshina, E. N., Goering, E., Dedkov, Y. S.

{Applied Physics Letters}, 96, 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Photon counting system for time-resolved experiments in multibunch mode

Puzic, A., Korhonen, T., Kalantari, B., Raabe, J., Quitmann, C., Jüllig, P., Bommer, L., Goll, D., Schütz, G., Wintz, S., Strache, T., Körner, M., Markó, D., Bunce, C., Fassbender, J.

{Synchrotron Radiation News}, 23(2):26-32, 2010 (article)

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link (url) DOI [BibTex]

link (url) DOI [BibTex]


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Coupling of Fe and uncompensated Mn moments in exchange-biased Fe/MnPd

Brück, S., Macke, S., Goering, E., Ji, X., Zhan, Q., Krishnan, K. M.

{Physical Review B}, 81(13), 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Remarks about spillover and hydrogen adsorption - Comments on the contributions of A.V. Talyzin and R.T. Yang

Hirscher, M.

{Microporous and Mesoporous Materials}, 135, pages: 209-210, 2010 (article)

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DOI [BibTex]


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Grain boundary ridges and triple lines

Straumal, B. B., Sursaeva, V. G., Baretzky, B.

{Scripta Materialia}, 62(12):924-927, 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Contact angles by the solid-phase grain boundary wetting (coverage) in the Co-Cu system

Straumal, B. B., Kogtenkova, O. A., Straumal, A. B., Kuchyeyev, Y. O., Baretzky, B.

In 45, pages: 4271-4275, Glasgow, Scotland, 2010 (inproceedings)

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DOI [BibTex]

DOI [BibTex]


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Expanding micelle nanolithography to the self-assembly of multicomponent core-shell nanoparticles

Mbenkum, B. N., D\’\iaz-Ortiz, A., Gu, L., van Aken, P. A., Schütz, G.

{Journal of the American Chemical Society}, 132(31):10671-10673, 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Entnetzung verspannter Filme

Reindl, A.

Universität Stuttgart, Stuttgart, 2010 (mastersthesis)

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[BibTex]

[BibTex]


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Advanced ferromagnetic nanostructures

Goll, D.

Universität Stuttgart, Stuttgart, 2010 (phdthesis)

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[BibTex]

[BibTex]


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Wasserstoff in funktionellen Dünnschichtsystemen

Honert, J.

Universität Stuttgart, Stuttgart, 2010 (mastersthesis)

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[BibTex]

[BibTex]


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Hydrogen spillover measurements of unbridged and bridged metal-organic frameworks - revisited

Campesi, R., Cuevas, F., Latroche, M., Hirscher, M.

{Physical Chemistry Chemical Physics}, 12, pages: 10457-10459, 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Relating Gilbert damping and ultrafast laser-induced demagnetization

Fähnle, M., Seib, J., Illg, C.

{Physical Review B}, 82, 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Ferromagnetic properties of the Mn-doped nanograined ZnO films

Straumal, B. B., Protasova, S. G., Mazilkin, A. A., Myatiev, A. A., Straumal, P. B., Schütz, G., Goering, E., Baretzky, B.

{Journal of Applied Physics}, 108, 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Unusual super-ductility at room temperature in an ultrafine-grained aluminum alloy

Valiev, R. Z., Murashkin, M. Y., Kilmametov, A., Straumal, B., Chinh, N. Q., Langdon, T.

In 45, pages: 4718-4724, Seattle, WA, USA, 2010 (inproceedings)

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DOI [BibTex]

DOI [BibTex]


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Demagnetization on the fs time-scale by the Elliott-Yafet mechanism

Steiauf, D., Illg, C., Fähnle, M.

In 200, Karlsruhe, Germany, 2010 (inproceedings)

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DOI [BibTex]

DOI [BibTex]


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Ubiquity of ferromagnetic signals in common diamagnetic oxide crystals

Khalid, M., Setzer, A., Ziese, M., Esquinazi, P., Spemann, D., Pöppl, A., Goering, E.

{Physical Review B}, 81(21), 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Calculation of the Gilbert damping matrix at low scattering rates in Gd

Seib, J., Fähnle, M.

{Physical Review B}, 82, 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Adsorption technologies

Schmitz, B., Hirscher, M.

In Hydrogen and Fuel Cells, pages: 431-445, WILEY-VCH, Weinheim, 2010 (incollection)

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[BibTex]

[BibTex]


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Swift heavy ions for controlled modification of soft magnetic properties of Fe0.85N0.15 thin film

Gupta, R., Gupta, A., Bhatt, R., Rüffer, R., Avasthi, D. K.

{Journal of Physics: Condensed Matter}, 22(22), 2010 (article)

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DOI [BibTex]

DOI [BibTex]


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Constrained Accelerations for Controlled Geometric Reduction: Sagittal-Plane Decoupling for Bipedal Locomotion

Gregg, R., Righetti, L., Buchli, J., Schaal, S.

In 2010 10th IEEE-RAS International Conference on Humanoid Robots, pages: 1-7, IEEE, Nashville, USA, 2010 (inproceedings)

Abstract
Energy-shaping control methods have produced strong theoretical results for asymptotically stable 3D bipedal dynamic walking in the literature. In particular, geometric controlled reduction exploits robot symmetries to control momentum conservation laws that decouple the sagittal-plane dynamics, which are easier to stabilize. However, the associated control laws require high-dimensional matrix inverses multiplied with complicated energy-shaping terms, often making these control theories difficult to apply to highly-redundant humanoid robots. This paper presents a first step towards the application of energy-shaping methods on real robots by casting controlled reduction into a framework of constrained accelerations for inverse dynamics control. By representing momentum conservation laws as constraints in acceleration space, we construct a general expression for desired joint accelerations that render the constraint surface invariant. By appropriately choosing an orthogonal projection, we show that the unconstrained (reduced) dynamics are decoupled from the constrained dynamics. Any acceleration-based controller can then be used to stabilize this planar subsystem, including passivity-based methods. The resulting control law is surprisingly simple and represents a practical way to employ control theoretic stability results in robotic platforms. Simulated walking of a 3D compass-gait biped show correspondence between the new and original controllers, and simulated motions of a 16-DOF humanoid demonstrate the applicability of this method.

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link (url) DOI [BibTex]

link (url) DOI [BibTex]


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Inverse dynamics with optimal distribution of ground reaction forces for legged robot

Righetti, L., Buchli, J., Mistry, M., Schaal, S.

In Proceedings of the 13th International Conference on Climbing and Walking Robots (CLAWAR), pages: 580-587, Nagoya, Japan, sep 2010 (inproceedings)

Abstract
Contact interaction with the environment is crucial in the design of locomotion controllers for legged robots, to prevent slipping for example. Therefore, it is of great importance to be able to control the effects of the robots movements on the contact reaction forces. In this contribution, we extend a recent inverse dynamics algorithm for floating base robots to optimize the distribution of contact forces while achieving precise trajectory tracking. The resulting controller is algorithmically simple as compared to other approaches. Numerical simulations show that this result significantly increases the range of possible movements of a humanoid robot as compared to the previous inverse dynamics algorithm. We also present a simplification of the result where no inversion of the inertia matrix is needed which is particularly relevant for practical use on a real robot. Such an algorithm becomes interesting for agile locomotion of robots on difficult terrains where the contacts with the environment are critical, such as walking over rough or slippery terrain.

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DOI [BibTex]

DOI [BibTex]