检索结果-内蒙古大学图书馆

IEEE International Conference on Robotics and Automation (ICRA)

作者： Daniel Kappler Jeannette Bohg Stefan Schaal Autonomous Motion Department at the Max-Planck-Institute for Intelligent Systems Tübingen Germany Computational Learning and Motor Control lab at the University of Southern California Los Angeles CA USA

We propose a new large-scale database containing grasps that are applied to a large set of objects from numerous categories. These grasps are generated in simulation and are annotated with different grasp stability metrics. We use a descriptive and efficient representation of the local object shape at which each grasp is applied. Given this data, we present a two-fold analysis: (i) We use crowdsourcing to analyze the correlation of the metrics with grasp success as predicted by humans. The results show that the metric based on physics simulation is a more consistent predictor for grasp success than the standard υ-metric. The results also support the hypothesis that human labels are not required for good ground truth grasp data. Instead the physics-metric can be used to generate datasets in simulation that may then be used to bootstrap learning in the real world. (ii) We apply a deep learning method and show that it can better leverage the large-scale database for prediction of grasp success compared to logistic regression. Furthermore, the results suggest that labels based on the physics-metric are less noisy than those from the υ-metric and therefore lead to a better classification performance.

关键词： Databases Robots Shape Three-dimensional displays Stability analysis Noise measurement

来源：评论

学校读者我要写书评

暂无评论

Inverse kinematics for humanoid robots

Inverse kinematics for humanoid robots

引用

IEEE International Conference on Robotics and Automation (ICRA)

作者： G. Tevatia S. Schaal Kawato Dynamic Brain Project ERATO Japan Science and Technology Agency Kyoto Japan Computational Learning and Motor Control Laboratory University of Southern California Los Angeles CA USA

Real-time control of the end-effector 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 humanoid robot.

关键词： Humanoid robots Jacobian matrices Robot kinematics Optimization methods Manipulators Motion control Orbital robotics Actuators Null space motor drives

来源：评论

学校读者我要写书评

暂无评论

Parameter learning for improving binary descriptor matching

Parameter learning for improving binary descriptor matching

引用

IEEE/RSJ International Conference on Intelligent Robots and Systems

作者： Bharath Sankaran Srikumar Ramalingam Yuichi Taguchi Computational Learning and Motor Control Lab University of Southern California Los Angeles 90089 United States of America Mitsubishi Electric Research Labs Cambridge MA 02139 United States of America

ISBN: (纸本)9781509037636

Binary descriptors allow fast detection and matching algorithms in computer vision problems. Though binary descriptors can be computed at almost two orders of magnitude faster than traditional gradient based descriptors, they suffer from poor matching accuracy in challenging conditions. In this paper we propose three improvements for binary descriptors in their computation and matching that enhance their performance in comparison to traditional binary and non-binary descriptors without compromising their speed. This is achieved by learning some weights and threshold parameters that allow customized matching under some variations such as lighting and viewpoint. Our suggested improvements can be easily applied to any binary descriptor. We demonstrate our approach on the ORB (Oriented FAST and Rotated BRIEF) descriptor and compare its performance with the traditional ORB and SIFT descriptors on a wide variety of datasets. In all instances, our enhancements outperform standard ORB and are comparable to SIFT.

关键词： Hamming distance Lighting Standards Training data Feature extraction Measurement Real-time systems

来源：评论

学校读者我要写书评

暂无评论

Dependence of orientation tuning on recurrent excitation and inhibition in a network model of V1

Dependence of orientation tuning on recurrent excitation and...

引用

22nd Annual Conference on Neural Information Processing Systems, NIPS 2008

作者： Wimmer, Klaus Stimberg, Marcel Martin, Robert Schwabe, Lars Mariño, Jorge Schummers, James Lyon, David C. Sur, Mriganka Obermayer, Klaus Bernstein Center for Computational Neuroscience Technische Universität Berlin Germany Dept of Computer Science and Electrical Engineering University of Rostock Germany Dept of Medicine Neuroscience and Motor Control Group Univ. A Coruña Spain Dept of Brain and Cognitive Sci Picower Ctr for Learning and Memory MIT Cambridge United States Dept of Anatomy and Neurobiology University of California Irvine United States

ISBN: (纸本)9781605609492

The computational role of the local recurrent network in primary visual cortex is still a matter of debate. To address this issue, we analyze intracellular recording data of cat V1, which combine measuring the tuning of a range of neuronal properties with a precise localization of the recording sites in the orientation preference map. For the analysis, we consider a network model of Hodgkin-Huxley type neurons arranged according to a biologically plausible two-dimensional topographic orientation preference map. We then systematically vary the strength of the recurrent excitation and inhibition relative to the strength of the afferent input. Each parametrization gives rise to a different model instance for which the tuning of model neurons at different locations of the orientation map is compared to the experimentally measured orientation tuning of membrane potential, spike output, excitatory, and inhibitory conductances. A quantitative analysis shows that the data provides strong evidence for a network model in which the afferent input is dominated by strong, balanced contributions of recurrent excitation and inhibition. This recurrent regime is close to a regime of "instability", where strong, self-sustained activity of the network occurs. The firing rate of neurons in the best-fitting network is particularly sensitive to small modulations of model parameters, which could be one of the functional benefits of a network operating in this particular regime.

关键词： Neurons

来源：评论

学校读者我要写书评

暂无评论

Probabilistic Recurrent State-Space Models

arXiv

引用

arXiv 2018年

作者： Doerr, Andreas Daniel, Christian Schiegg, Martin Nguyen-Tuong, Duy Schaal, Stefan Toussaint, Marc Trimpe, Sebastian Bosch Center for Artificial Intelligence Renningen Germany Max Planck Institute for Intelligent Systems Stuttgart/Tübingen Germany Computational Learning and Motor Control Lab University of Southern California United States Machine Learning and Robotics Lab University of Stuttgart Germany

State-space models (SSMs) are a highly expressive model class for learning patterns in time series data and for system identification. Deterministic versions of SSMs (e.g. LSTMs) proved extremely successful in modeling complex time series data. Fully probabilistic SSMs, however, are often found hard to train, even for smaller problems. To overcome this limitation, we propose a novel model formulation and a scalable training algorithm based on doubly stochastic variational inference and Gaussian processes. In contrast to existing work, the proposed variational approximation allows one to fully capture the latent state temporal correlations. These correlations are the key to robust training. The effectiveness of the proposed PR-SSM is evaluated on a set of realworld benchmark datasets in comparison to stateof-the-art probabilistic model learning methods. Scalability and robustness are demonstrated on a high dimensional problem. Copyright © 2018, The Authors. All rights reserved.

关键词： State space methods

来源：评论

学校读者我要写书评

暂无评论

Reinforcement learning of impedance control in stochastic force fields

Reinforcement learning of impedance control in stochastic fo...

引用

IEEE International Conference on Development and learning, ICDL

作者： Freek Stulp Jonas Buchli Alice Ellmer Michael Mistry Evangelos Theodorou Stefan Schaal Computational Learning and Motor Control Laboratory University of Southern California Los Angeles CA USA Department of Advanced Robotics Italian Institute of Technology Genova Italy Disney Research Pittsburgh PA USA

Variable impedance control is essential for ensuring robust and safe physical interaction with the environment. As demonstrated in numerous force field experiments, humans combine two strategies to adapt their impedance to external perturbations: 1) if perturbations are unpredictable, subjects increase their impedance through co-contraction; 2) if perturbations are predictable, subjects learn a feed-forward command to counter the known perturbation. In this paper, we apply the force field paradigm to a simulated 7-DOF robot, by exerting stochastic forces on the robot's end-effector. The robot `subject' uses our model-free reinforcement learning algorithm PI2 to simultaneously learn the end-effector trajectories and variable impedance schedules. We demonstrate how the robot learns the same two-fold strategy to perturbation rejection as humans do, resulting in qualitatively similar behavior. Our results provide a biologically plausible approach to learning appropriate impedances purely from experience, without requiring a model of either body or environment dynamics.

关键词： computational modeling Noise measurement

来源：评论

学校读者我要写书评

暂无评论

Robot arm pose estimation through pixel-wise part classification

Robot arm pose estimation through pixel-wise part classifica...

引用

IEEE International Conference on Robotics and Automation (ICRA)

作者： Jeannette Bohg Javier Romero Alexander Herzog Stefan Schaal Autonomous Motion Department Perceiving Systems Max-Planck-Institute for Intelligent Systems Tübingen Germany Computational Learning and Motor Control lab University of Southern California Los Angeles CA USA

We propose to frame the problem of marker-less robot arm pose estimation as a pixel-wise part classification problem. As input, we use a depth image in which each pixel is classified to be either from a particular robot part or the background. The classifier is a random decision forest trained on a large number of synthetically generated and labeled depth images. From all the training samples ending up at a leaf node, a set of offsets is learned that votes for relative joint positions. Pooling these votes over all foreground pixels and subsequent clustering gives us an estimate of the true joint positions. Due to the intrinsic parallelism of pixel-wise classification, this approach can run in super real-time and is more efficient than previous ICP-like methods. We quantitatively evaluate the accuracy of this approach on synthetic data. We also demonstrate that the method produces accurate joint estimates on real data despite being purely trained on synthetic data.

关键词： Joints Three-dimensional displays Robot sensing systems Estimation Training data Kinematics

来源：评论

学校读者我要写书评

暂无评论

Toward simple control for complex, autonomous robotic applications: Combining discrete and rhythmic motor primitives

Toward simple control for complex, autonomous robotic applic...

引用

作者： Degallier, Sarah Righetti, Ludovic Gay, Sebastien Ijspeert, Auke CNBI Laboratory School of Engineering EPFL Ecole Polytechnique Fédérale de Lausanne Lausanne 1015 Switzerland Biorobotics Laboratory School of Engineering EPFL Ecole Polytechnique Fédérale de Lausanne Lausanne 1015 Switzerland Computational Learning and Motor Control Lab Computer Science Neurosciences and Biomedical Engineering University of Southern California Los Angeles CA 90089 United States

Vertebrates are able to quickly adapt to new environments in a very robust, seemingly effortless way. To explain both this adaptivity and robustness, a very promising perspective in neurosciences is the modular approach to movement generation: Movements results from combinations of a finite set of stable motor primitives organized at the spinal level. In this article we apply this concept of modular generation of movements to the control of robots with a high number of degrees of freedom, an issue that is challenging notably because planning complex, multidimensional trajectories in time-varying environments is a laborious and costly process. We thus propose to decrease the complexity of the planning phase through the use of a combination of discrete and rhythmic motor primitives, leading to the decoupling of the planning phase (i.e. the choice of behavior) and the actual trajectory generation. Such implementation eases the control of, and the switch between, different behaviors by reducing the dimensionality of the high-level commands. Moreover, since the motor primitives are generated by dynamical systems, the trajectories can be smoothly modulated, either by high-level commands to change the current behavior or by sensory feedback information to adapt to environmental constraints. In order to show the generality of our approach, we apply the framework to interactive drumming and infant crawling in a humanoid robot. These experiments illustrate the simplicity of the control architecture in terms of planning, the integration of different types of feedback (vision and contact) and the capacity of autonomously switching between different behaviors (crawling and simple reaching). © 2011 Springer Science+Business Media, LLC.

关键词： Anthropomorphic robots

来源：评论

学校读者我要写书评

暂无评论

control of legged robots with optimal distribution of contact forces

Control of legged robots with optimal distribution of contac...

引用

IEEE-RAS International Conference on Humanoid Robots

作者： Ludovic Righetti Jonas Buchli Michael Mistry Stefan Schaal Computational Learning and Motor Control Laboratory University of Southern California Los Angeles CA USA Department of Advanced Robotics Italian Institute of Technology Genova Italy Disney Research Pittsburgh Pittsburgh PA USA

The development of agile and safe humanoid robots require controllers that guarantee both high tracking performance and compliance with the environment. More specifically, the control of contact interaction is of crucial importance for robots that will actively interact with their environment. Model-based controllers such as inverse dynamics or operational space control are very appealing as they offer both high tracking performance and compliance. However, while widely used for fully actuated systems such as manipulators, they are not yet standard controllers for legged robots such as humanoids. Indeed such robots are fundamentally different from manipulators as they are underactuated due to their floating-base and subject to switching contact constraints. In this paper we present an inverse dynamics controller for legged robots that use torque redundancy to create an optimal distribution of contact constraints. The resulting controller is able to minimize, given a desired motion, any quadratic cost of the contact constraints at each instant of time. In particular we show how this can be used to minimize tangential forces during locomotion, therefore significantly improving the locomotion of legged robots on difficult terrains. In addition to the theoretical result, we present simulations of a humanoid and a quadruped robot, as well as experiments on a real quadruped robot that demonstrate the advantages of the controller.

关键词： Torque Dynamics Acceleration Redundancy Legged locomotion Joints

来源：评论

学校读者我要写书评

暂无评论

Combining learned and analytical models for predicting action effects from sensory data

arXiv

引用

arXiv 2017年

作者： Kloss, Alina Schaal, Stefan Bohg, Jeannette Autonomous Motion Department Max Planck Institute for Intelligent Systems Germany Computational Learning and Motor Control Lab University of Southern California United States Department of Computer Science Stanford University United States

One of the most basic skills a robot should possess is predicting the effect of physical interactions with objects in the environment. This enables optimal action selection to reach a certain goal state. Traditionally, dynamics are approximated by physics-based analytical models. These models rely on specific state representations that may be hard to obtain from raw sensory data, especially if no knowledge of the object shape is assumed. More recently, we have seen learning approaches that can predict the effect of complex physical interactions directly from sensory input. It is however an open question how far these models generalize beyond their training data. In this work, we investigate the advantages and limitations of neural network based learning approaches for predicting the effects of actions based on sensory input and show how analytical and learned models can be combined to leverage the best of both worlds. As physical interaction task, we use planar pushing, for which there exists a well-known analytical model and a large realworld dataset. We propose to use a convolutional neural network to convert raw depth images or organized point clouds into a suitable representation for the analytical model and compare this approach to using neural networks for both, perception and prediction. A systematic evaluation of the proposed approach on a very large real-world dataset shows two main advantages of the hybrid architecture. Compared to a pure neural network, it significantly (i) reduces required training data and (ii) improves generalization to novel physical interaction. Copyright © 2017, The Authors. All rights reserved.

关键词： Forecasting

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：