布料的机器人操作的应用包括织物制造业到处理毯子和洗衣。布料操作对于机器人而言是挑战,这主要是由于它们的高度自由度,复杂的动力学和折叠或皱巴巴配置时的严重自我闭合。机器人操作的先前工作主要依赖于视觉传感器,这可能会对细粒度的操纵任务构成挑战,例如从一堆布上抓住所需数量的布料层。在本文中,我们建议将触觉传感用于布操作;我们将触觉传感器(Resin)连接到弗兰卡机器人的两个指尖之一,并训练分类器,以确定机器人是否正在抓住特定数量的布料层。在测试时间实验中,机器人使用此分类器作为其政策的一部分,使用触觉反馈来掌握一两个布层,以确定合适的握把。实验结果超过180次物理试验表明,与使用图像分类器的方法相比,所提出的方法优于不使用触觉反馈并具有更好地看不见布的基准。代码,数据和视频可在https://sites.google.com/view/reskin-cloth上找到。
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最近的工作表明,2臂“ Fling”运动对于服装平滑可能是有效的。我们考虑单臂弹性运动。与几乎不需要机器人轨迹参数调整的2臂fling运动不同,单臂fling运动对轨迹参数很敏感。我们考虑一个单一的6多机器人臂,该机器人臂学习跨越轨迹以实现高衣覆盖率。给定服装抓握点,机器人在物理实验中探索了不同的参数化fling轨迹。为了提高学习效率,我们提出了一种粗到精细的学习方法,该方法首先使用多军匪徒(MAB)框架有效地找到候选动作,然后通过连续优化方法来完善。此外,我们提出了基于Fling Fall结果不确定性的新颖培训和执行时间停止标准。与基线相比,我们表明所提出的方法显着加速学习。此外,由于通过自学人员收集的类似服装的先前经验,新服装的MAB学习时间最多减少了87%。我们评估了6种服装类型:毛巾,T恤,长袖衬衫,礼服,汗衫和牛仔裤。结果表明,使用先前的经验,机器人需要30分钟以下的时间才能为达到60-94%覆盖率的新型服装学习一项动作。
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使用单个参数化动态动作操纵可变形物体对蝇钓,宽毯和播放洗牌板等任务非常有用。此类任务作为输入所需的最终状态并输出一个参数化的开环动态机器人动作,它向最终状态产生轨迹。这对于具有涉及摩擦力的复杂动态的长地平轨迹尤其具有挑战性。本文探讨了平面机器人铸造的任务(PRC):其中握住电缆一端的机器人手腕的一个平面运动使另一端朝向所需的目标滑过平面。 PRC允许电缆达到机器人工作区以外的点,并在家庭,仓库和工厂中具有电缆管理的应用。为了有效地学习给定电缆的PRC策略,我们提出了Real2Sim2Real,一个自动收集物理轨迹示例的自我监督框架,以使用差分演进调谐动态模拟器的参数,生成许多模拟示例,然后使用加权学习策略模拟和物理数据的组合。我们使用三种模拟器,ISAAC健身房分段,ISAAC健身房 - 混合动力和Pybullet,两个功能近似器,高斯工艺和神经网络(NNS),以及具有不同刚度,扭转和摩擦的三个电缆。结果每条电缆的16个举出的测试目标表明,使用ISAAC健身房分段的NN PRC策略达到中位误差距离(电缆长度的百分比),范围为8%至14%,表现优于真实或仅培训的基线和政策。只有模拟的例子。 https://tinyurl.com/robotcast可以使用代码,数据和视频。
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In this paper, we propose a new approach to learned optimization. As common in the literature, we represent the computation of the update step of the optimizer with a neural network. The parameters of the optimizer are then learned on a set of training optimization tasks, in order to perform minimisation efficiently. Our main innovation is to propose a new neural network architecture for the learned optimizer inspired by the classic BFGS algorithm. As in BFGS, we estimate a preconditioning matrix as a sum of rank-one updates but use a transformer-based neural network to predict these updates jointly with the step length and direction. In contrast to several recent learned optimization approaches, our formulation allows for conditioning across different dimensions of the parameter space of the target problem while remaining applicable to optimization tasks of variable dimensionality without retraining. We demonstrate the advantages of our approach on a benchmark composed of objective functions traditionally used for evaluation of optimization algorithms, as well as on the real world-task of physics-based reconstruction of articulated 3D human motion.
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We apply Physics Informed Neural Networks (PINNs) to the problem of wildfire fire-front modelling. The PINN is an approach that integrates a differential equation into the optimisation loss function of a neural network to guide the neural network to learn the physics of a problem. We apply the PINN to the level-set equation, which is a Hamilton-Jacobi partial differential equation that models a fire-front with the zero-level set. This results in a PINN that simulates a fire-front as it propagates through a spatio-temporal domain. We demonstrate the agility of the PINN to learn physical properties of a fire under extreme changes in external conditions (such as wind) and show that this approach encourages continuity of the PINN's solution across time. Furthermore, we demonstrate how data assimilation and uncertainty quantification can be incorporated into the PINN in the wildfire context. This is significant contribution to wildfire modelling as the level-set method -- which is a standard solver to the level-set equation -- does not naturally provide this capability.
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Object compositing based on 2D images is a challenging problem since it typically involves multiple processing stages such as color harmonization, geometry correction and shadow generation to generate realistic results. Furthermore, annotating training data pairs for compositing requires substantial manual effort from professionals, and is hardly scalable. Thus, with the recent advances in generative models, in this work, we propose a self-supervised framework for object compositing by leveraging the power of conditional diffusion models. Our framework can hollistically address the object compositing task in a unified model, transforming the viewpoint, geometry, color and shadow of the generated object while requiring no manual labeling. To preserve the input object's characteristics, we introduce a content adaptor that helps to maintain categorical semantics and object appearance. A data augmentation method is further adopted to improve the fidelity of the generator. Our method outperforms relevant baselines in both realism and faithfulness of the synthesized result images in a user study on various real-world images.
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Learning linear temporal logic (LTL) formulas from examples labeled as positive or negative has found applications in inferring descriptions of system behavior. We summarize two methods to learn LTL formulas from examples in two different problem settings. The first method assumes noise in the labeling of the examples. For that, they define the problem of inferring an LTL formula that must be consistent with most but not all of the examples. The second method considers the other problem of inferring meaningful LTL formulas in the case where only positive examples are given. Hence, the first method addresses the robustness to noise, and the second method addresses the balance between conciseness and specificity (i.e., language minimality) of the inferred formula. The summarized methods propose different algorithms to solve the aforementioned problems, as well as to infer other descriptions of temporal properties, such as signal temporal logic or deterministic finite automata.
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In cooperative Multi-Agent Planning (MAP), a set of goals has to be achieved by a set of agents. Independently of whether they perform a pre-assignment of goals to agents or they directly search for a solution without any goal assignment, most previous works did not focus on a fair distribution/achievement of goals by agents. This paper adapts well-known fairness schemes to MAP, and introduces two novel approaches to generate cost-aware fair plans. The first one solves an optimization problem to pre-assign goals to agents, and then solves a centralized MAP task using that assignment. The second one consists of a planning-based compilation that allows solving the joint problem of goal assignment and planning while taking into account the given fairness scheme. Empirical results in several standard MAP benchmarks show that these approaches outperform different baselines. They also show that there is no need to sacrifice much plan cost to generate fair plans.
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Animals run robustly in diverse terrain. This locomotion robustness is puzzling because axon conduction velocity is limited to a few ten meters per second. If reflex loops deliver sensory information with significant delays, one would expect a destabilizing effect on sensorimotor control. Hence, an alternative explanation describes a hierarchical structure of low-level adaptive mechanics and high-level sensorimotor control to help mitigate the effects of transmission delays. Motivated by the concept of an adaptive mechanism triggering an immediate response, we developed a tunable physical damper system. Our mechanism combines a tendon with adjustable slackness connected to a physical damper. The slack damper allows adjustment of damping force, onset timing, effective stroke, and energy dissipation. We characterize the slack damper mechanism mounted to a legged robot controlled in open-loop mode. The robot hops vertically and planar over varying terrains and perturbations. During forward hopping, slack-based damping improves faster perturbation recovery (up to 170%) at higher energetic cost (27%). The tunable slack mechanism auto-engages the damper during perturbations, leading to a perturbation-trigger damping, improving robustness at minimum energetic cost. With the results from the slack damper mechanism, we propose a new functional interpretation of animals' redundant muscle tendons as tunable dampers.
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Generative Adversarial Networks (GANs) have received wide acclaim among the machine learning (ML) community for their ability to generate realistic 2D images. ML is being applied more often to complex problems beyond those of computer vision. However, current frameworks often serve as black boxes and lack physics embeddings, leading to poor ability in enforcing constraints and unreliable models. In this work, we develop physics embeddings that can be stringently imposed, referred to as hard constraints, in the neural network architecture. We demonstrate their capability for 3D turbulence by embedding them in GANs, particularly to enforce the mass conservation constraint in incompressible fluid turbulence. In doing so, we also explore and contrast the effects of other methods of imposing physics constraints within the GANs framework, especially penalty-based physics constraints popular in literature. By using physics-informed diagnostics and statistics, we evaluate the strengths and weaknesses of our approach and demonstrate its feasibility.
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