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    Ma Z-B, Yang Y, Liu Y-X, Bharath AAet al., 2016,

    Recurrently Decomposable 2-D Convolvers for FPGA-Based Digital Image Processing

    Pantic M, Evers V, Deisenroth M, Merino L, Schuller Bet al., 2016,

    Social and Affective Robotics Tutorial

    , 24th ACM Multimedia Conference (MM), Publisher: ASSOC COMPUTING MACHINERY, Pages: 1477-1478
    Shaloudegi K, Gyorgy A, Szepesvari C, Xu Wet al., 2016,

    SDP relaxation with randomized rounding for energy disaggregation

    , The Thirtieth Annual Conference on Neural Information Processing Systems (NIPS), Publisher: Neutral Information Processing Systems Foundation, Inc.

    We develop a scalable, computationally efficient method for the task of energydisaggregation for home appliance monitoring. In this problem the goal is toestimate the energy consumption of each appliance over time based on the totalenergy-consumption signal of a household. The current state of the art is to modelthe problem as inference in factorial HMMs, and use quadratic programming tofind an approximate solution to the resulting quadratic integer program. Here wetake a more principled approach, better suited to integer programming problems,and find an approximate optimum by combining convex semidefinite relaxationsrandomized rounding, as well as a scalable ADMM method that exploits the specialstructure of the resulting semidefinite program. Simulation results both in syntheticand real-world datasets demonstrate the superiority of our method.

    de Montjoye YKJV, Rocher L, Pentland AS, 2016,

    bandicoot: an open-source Python toolbox to analyze mobile phone metadata

    , Journal of Machine Learning Research, Vol: 17, ISSN: 1532-4435

    bandicoot is an open-source Python toolbox to extract more than 1442 features from standard mobile phone metadata. bandicoot makes it easy for machine learning researchers and practitioners to load mobile phone data, to analyze and visualize them, and to extract robust features which can be used for various classification and clustering tasks. Emphasis is put on ease of use, consistency, and documentation. bandicoot has no dependencies and is distributed under MIT license

    Calandra R, Ivaldi S, Deisenroth MP, Peters Jet al., 2015,

    Learning torque control in presence of contacts using tactile sensing from robot skin

    , Pages: 690-695, ISSN: 2164-0572

    © 2015 IEEE. Whole-body control in unknown environments is challenging: Unforeseen contacts with obstacles can lead to poor tracking performance and potential physical damages of the robot. Hence, a whole-body control approach for future humanoid robots in (partially) unknown environments needs to take contact sensing into account, e.g., by means of artificial skin. However, translating contacts from skin measurements into physically well-understood quantities can be problematic as the exact position and strength of the contact needs to be converted into torques. In this paper, we suggest an alternative approach that directly learns the mapping from both skin and the joint state to torques. We propose to learn such an inverse dynamics models with contacts using a mixture-of-contacts approach that exploits the linear superimposition of contact forces. The learned model can, making use of uncalibrated tactile sensors, accurately predict the torques needed to compensate for the contact. As a result, tracking of trajectories with obstacles and tactile contact can be executed more accurately. We demonstrate on the humanoid robot iCub that our approach improve the tracking error in presence of dynamic contacts.

    Calandra R, Ivaldi S, Deisenroth MP, Rueckert E, Peters Jet al., 2015,

    Learning inverse dynamics models with contacts

    , Pages: 3186-3191, ISSN: 1050-4729

    © 2015 IEEE. In whole-body control, joint torques and external forces need to be estimated accurately. In principle, this can be done through pervasive joint-torque sensing and accurate system identification. However, these sensors are expensive and may not be integrated in all links. Moreover, the exact position of the contact must be known for a precise estimation. If contacts occur on the whole body, tactile sensors can estimate the contact location, but this requires a kinematic spatial calibration, which is prone to errors. Accumulating errors may have dramatic effects on the system identification. As an alternative to classical model-based approaches we propose a data-driven mixture-of-experts learning approach using Gaussian processes. This model predicts joint torques directly from raw data of tactile and force/torque sensors. We compare our approach to an analytic model-based approach on real world data recorded from the humanoid iCub. We show that the learned model accurately predicts the joint torques resulting from contact forces, is robust to changes in the environment and outperforms existing dynamic models that use of force/ torque sensor data.

    Deisenroth MP, Fox D, Rasmussen CE, 2015,

    Gaussian Processes for Data-Efficient Learning in Robotics and Control.

    , IEEE Trans Pattern Anal Mach Intell, Vol: 37, Pages: 408-423

    Autonomous learning has been a promising direction in control and robotics for more than a decade since data-driven learning allows to reduce the amount of engineering knowledge, which is otherwise required. However, autonomous reinforcement learning (RL) approaches typically require many interactions with the system to learn controllers, which is a practical limitation in real systems, such as robots, where many interactions can be impractical and time consuming. To address this problem, current learning approaches typically require task-specific knowledge in form of expert demonstrations, realistic simulators, pre-shaped policies, or specific knowledge about the underlying dynamics. In this paper, we follow a different approach and speed up learning by extracting more information from data. In particular, we learn a probabilistic, non-parametric Gaussian process transition model of the system. By explicitly incorporating model uncertainty into long-term planning and controller learning our approach reduces the effects of model errors, a key problem in model-based learning. Compared to state-of-the art RL our model-based policy search method achieves an unprecedented speed of learning. We demonstrate its applicability to autonomous learning in real robot and control tasks.

    Deisenroth MP, Ng JW, 2015,

    Distributed Gaussian processes

    , Pages: 1481-1490

    Copyright © 2015 by the author(s). To scale Gaussian processes (GPs) to large data sets we introduce the robust Bayesian Committee Machine (rBCM), a practical and scalable product-of-experts model for large-scale distributed GP regression. Unlike state-of-the-art sparse GP approximations, the rBCM is conceptually simple and does not rely on inducing or variational parameters. The key idea is to recursively distribute computations to independent computational units and, subsequently, re-combine them to form an overall result. Efficient closed-form inference allows for straightforward parallelisation and distributed computations with a small memory footprint. The rBCM is independent of the computational graph and can be used on heterogeneous computing infrastructures, ranging from laptops to clusters. With sufficient computing resources our distributed GP model can handle arbitrarily large data sets.

    Deisenroth MP, Ng JW, 2015,

    Distributed Gaussian Processes

    , 2015 International Conference on Machine Learning (ICML), Publisher: Journal of Machine Learning Research

    To scale Gaussian processes (GPs) to large datasets we introduce the robust Bayesian CommitteeMachine (rBCM), a practical and scalableproduct-of-experts model for large-scaledistributed GP regression. Unlike state-of-theartsparse GP approximations, the rBCM is conceptuallysimple and does not rely on inducingor variational parameters. The key idea is torecursively distribute computations to independentcomputational units and, subsequently, recombinethem to form an overall result. Efficientclosed-form inference allows for straightforwardparallelisation and distributed computations witha small memory footprint. The rBCM is independentof the computational graph and canbe used on heterogeneous computing infrastructures,ranging from laptops to clusters. With sufficientcomputing resources our distributed GPmodel can handle arbitrarily large data sets.

    Hu X, Prashanth LA, Gyorgy A, Szepesvari Cet al., 2015,

    (Bandit) Convex Optimization with Biased Noisy Gradient Oracles

    , 8th NIPS Workshop on Optimization for Machine Learning

    For bandit convex optimization we propose a model, where a gradient estimation oracle acts as anintermediary between a noisy function evaluation oracle and the algorithms. The algorithms cancontrol the bias-variance tradeoff in the gradient estimates. We prove lower and upper bounds forthe minimax error of algorithms that interact with the objective function by controlling this oracle.The upper bounds replicate many existing results (capturing the essence of existing proofs) while thelower bounds put a limit on the achievable performance in this setup. In particular, our results implythat no algorithm can achieve the optimal minimax error rate in stochastic bandit smooth convexoptimization.

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