游戏历史悠久的历史悠久地作为人工智能进步的基准。最近,使用搜索和学习的方法在一系列完美的信息游戏中表现出强烈的表现,并且使用游戏理论推理和学习的方法对特定的不完美信息扑克变体表示了很强的性能。我们介绍游戏玩家,一个通用算法,统一以前的方法,结合导游搜索,自助学习和游戏理论推理。游戏播放器是实现大型完美和不完美信息游戏中强大实证性能的第一个算法 - 这是一项真正的任意环境算法的重要一步。我们证明了游戏玩家是声音,融合到完美的游戏,因为可用的计算时间和近似容量增加。游戏播放器在国际象棋上达到了强大的表现,然后击败了最强大的公开可用的代理商,在头上没有限制德克萨斯州扑克(Slumbot),击败了苏格兰院子的最先进的代理人,这是一个不完美的信息游戏,说明了引导搜索,学习和游戏理论推理的价值。
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In recent years, nonlinear model predictive control (NMPC) has been extensively used for solving automotive motion control and planning tasks. In order to formulate the NMPC problem, different coordinate systems can be used with different advantages. We propose and compare formulations for the NMPC related optimization problem, involving a Cartesian and a Frenet coordinate frame (CCF/ FCF) in a single nonlinear program (NLP). We specify costs and collision avoidance constraints in the more advantageous coordinate frame, derive appropriate formulations and compare different obstacle constraints. With this approach, we exploit the simpler formulation of opponent vehicle constraints in the CCF, as well as road aligned costs and constraints related to the FCF. Comparisons to other approaches in a simulation framework highlight the advantages of the proposed approaches.
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Flexible robots may overcome the industry's major problems: safe human-robot collaboration and increased load-to-mass ratio. However, oscillations and high dimensional state space complicate the control of flexible robots. This work investigates nonlinear model predictive control (NMPC) of flexible robots -- for simultaneous planning and control -- modeled via the rigid finite element method. Although NMPC performs well in simulation, computational complexity prevents its deployment in practice. We show that imitation learning of NMPC with neural networks as function approximator can massively improve the computation time of the controller at the cost of slight performance loss and, more critically, loss of safety guarantees. We leverage a safety filter formulated as a simpler NMPC to recover safety guarantees. Experiments on a simulated three degrees of freedom flexible robot manipulator demonstrate that the average computational time of the proposed safe approximate NMPC controller is 3.6 ms while of the original NMPC is 11.8 ms. Fast and safe approximate NMPC might facilitate the industry's adoption of flexible robots and new solutions for similar problems, e.g., deformable object manipulation and soft robot control.
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Besides the recent impressive results on reinforcement learning (RL), safety is still one of the major research challenges in RL. RL is a machine-learning approach to determine near-optimal policies in Markov decision processes (MDPs). In this paper, we consider the setting where the safety-relevant fragment of the MDP together with a temporal logic safety specification is given and many safety violations can be avoided by planning ahead a short time into the future. We propose an approach for online safety shielding of RL agents. During runtime, the shield analyses the safety of each available action. For any action, the shield computes the maximal probability to not violate the safety specification within the next $k$ steps when executing this action. Based on this probability and a given threshold, the shield decides whether to block an action from the agent. Existing offline shielding approaches compute exhaustively the safety of all state-action combinations ahead of time, resulting in huge computation times and large memory consumption. The intuition behind online shielding is to compute at runtime the set of all states that could be reached in the near future. For each of these states, the safety of all available actions is analysed and used for shielding as soon as one of the considered states is reached. Our approach is well suited for high-level planning problems where the time between decisions can be used for safety computations and it is sustainable for the agent to wait until these computations are finished. For our evaluation, we selected a 2-player version of the classical computer game SNAKE. The game represents a high-level planning problem that requires fast decisions and the multiplayer setting induces a large state space, which is computationally expensive to analyse exhaustively.
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We present an approach for safe trajectory planning, where a strategic task related to autonomous racing is learned sample-efficient within a simulation environment. A high-level policy, represented as a neural network, outputs a reward specification that is used within the cost function of a parametric nonlinear model predictive controller (NMPC). By including constraints and vehicle kinematics in the NLP, we are able to guarantee safe and feasible trajectories related to the used model. Compared to classical reinforcement learning (RL), our approach restricts the exploration to safe trajectories, starts with a good prior performance and yields full trajectories that can be passed to a tracking lowest-level controller. We do not address the lowest-level controller in this work and assume perfect tracking of feasible trajectories. We show the superior performance of our algorithm on simulated racing tasks that include high-level decision making. The vehicle learns to efficiently overtake slower vehicles and to avoid getting overtaken by blocking faster vehicles.
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The short-term prediction of precipitation is critical in many areas of life. Recently, a large body of work was devoted to forecasting radar reflectivity images. The radar images are available only in areas with ground weather radars. Thus, we aim to predict high-resolution precipitation from lower-resolution satellite radiance images. A neural network called WeatherFusionNet is employed to predict severe rain up to eight hours in advance. WeatherFusionNet is a U-Net architecture that fuses three different ways to process the satellite data; predicting future satellite frames, extracting rain information from the current frames, and using the input sequence directly. Using the presented method, we achieved 1st place in the NeurIPS 2022 Weather4Cast Core challenge. The code and trained parameters are available at \url{https://github.com/Datalab-FIT-CTU/weather4cast-2022}.
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机器学习与服务(MLAAS)已成为广泛的范式,即使是通过例如,也是客户可用的最复杂的机器学习模型。一个按要求的原则。这使用户避免了数据收集,超参数调整和模型培训的耗时过程。但是,通过让客户访问(预测)模型,MLAAS提供商危害其知识产权,例如敏感培训数据,优化的超参数或学到的模型参数。对手可以仅使用预测标签创建模型的副本,并以(几乎)相同的行为。尽管已经描述了这种攻击的许多变体,但仅提出了零星的防御策略,以解决孤立的威胁。这增加了对模型窃取领域进行彻底系统化的必要性,以全面了解这些攻击是成功的原因,以及如何全面地捍卫它们。我们通过对模型窃取攻击,评估其性能以及探索不同设置中相应的防御技术来解决这一问题。我们为攻击和防御方法提出了分类法,并提供有关如何根据目标和可用资源选择正确的攻击或防御策略的准则。最后,我们分析了当前攻击策略使哪些防御能力降低。
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我们提出了一种新颖的方法来通过使用具有不同个性类型的代理来生成脚本。为了管理脚本中的字符交互,我们采用了模拟的戏剧网络。关于多个标准的自动和人类评估表明,我们的方法的表现优于基于香草-GPT2的基线。我们进一步引入了一个新的指标,以根据自然语言推论评估对话一致性并证明其有效性。
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高数据质量对于当今基于AI的系统至关重要。但是,尽管数据质量一直是研究的对象,但显然缺乏对潜在数据质量问题的研究(例如,模棱两可的,无关的价值)。这些问题本质上是潜在的,因此通常不明显。然而,它们可能与基于AI的系统(例如技术债务,数据引起的故障)的未来问题的风险增加有关。作为软件工程中代码气味的对应物,我们指的是数据气味的问题。本文概念化了数据的气味,并在基于AI的系统的背景下的原因,后果,检测和使用。此外,出现了36个数据气味的目录,分为三类(即可信度的气味,可理解的气味,一致性的气味)。此外,该文章概述了用于检测数据气味的工具支持,并提出了240多个现实世界数据集中初始气味检测的结果。
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We develop new theoretical results on matrix perturbation to shed light on the impact of architecture on the performance of a deep network. In particular, we explain analytically what deep learning practitioners have long observed empirically: the parameters of some deep architectures (e.g., residual networks, ResNets, and Dense networks, DenseNets) are easier to optimize than others (e.g., convolutional networks, ConvNets). Building on our earlier work connecting deep networks with continuous piecewise-affine splines, we develop an exact local linear representation of a deep network layer for a family of modern deep networks that includes ConvNets at one end of a spectrum and ResNets, DenseNets, and other networks with skip connections at the other. For regression and classification tasks that optimize the squared-error loss, we show that the optimization loss surface of a modern deep network is piecewise quadratic in the parameters, with local shape governed by the singular values of a matrix that is a function of the local linear representation. We develop new perturbation results for how the singular values of matrices of this sort behave as we add a fraction of the identity and multiply by certain diagonal matrices. A direct application of our perturbation results explains analytically why a network with skip connections (such as a ResNet or DenseNet) is easier to optimize than a ConvNet: thanks to its more stable singular values and smaller condition number, the local loss surface of such a network is less erratic, less eccentric, and features local minima that are more accommodating to gradient-based optimization. Our results also shed new light on the impact of different nonlinear activation functions on a deep network's singular values, regardless of its architecture.
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