动物行为是由与不同控制策略并行工作的多个大脑区域驱动的。我们提出了基础神经节中损失钢筋学习的生物学上合理的模型,该模型可以在这种建筑中学习。该模型说明了与动作相关的多巴胺活动调制,该调制不是由实现政策算法的以前模型捕获的。特别是,该模型预测,多巴胺活动标志着奖励预测误差(如经典模型)和“动作惊喜”的组合,这是对动作相对于基础神经节的当前政策的意外程度的衡量标准。在存在动作惊喜项的情况下,该模型实现了Q学习的近似形式。在基准导航和达到任务上,我们从经验上表明,该模型能够完全或部分由其他策略(例如其他大脑区域)学习。相比之下,没有动作惊喜术语的模型在存在其他政策的情况下遭受了损失,并且根本无法从完全由外部驱动的行为中学习。该模型为多巴胺活性提供了许多实验发现,提供了一个计算说明,这是基础神经节中的经典增强模型无法解释的。这些包括背侧和腹侧纹状体中不同水平的动作惊喜信号,通过实践减少了运动调节的多巴胺活性的量以及多巴胺活性的动作起始和运动学的表示。它还提供了进一步的预测,可以通过纹状体多巴胺活性的记录进行测试。
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在本文中,我们通过神经生成编码的神经认知计算框架(NGC)提出了一种无反向传播的方法,以机器人控制(NGC),设计了一种完全由强大的预测性编码/处理电路构建的代理,体现计划的原则。具体而言,我们制作了一种自适应剂系统,我们称之为主动预测性编码(ACTPC),该系统可以平衡内部生成的认知信号(旨在鼓励智能探索)与内部生成的仪器信号(旨在鼓励寻求目标行为)最终学习如何使用现实的机器人模拟器(即超现实的机器人套件)来控制各种模拟机器人系统以及复杂的机器人臂,以解决块提升任务并可能选择问题。值得注意的是,我们的实验结果表明,我们提出的ACTPC代理在面对稀疏(外部)奖励信号方面表现良好,并且具有竞争力或竞争性或胜过几种强大的基于反向Prop的RL方法。
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Synaptic plasticity allows cortical circuits to learn new tasks and to adapt to changing environments. How do cortical circuits use plasticity to acquire functions such as decision-making or working memory? Neurons are connected in complex ways, forming recurrent neural networks, and learning modifies the strength of their connections. Moreover, neurons communicate emitting brief discrete electric signals. Here we describe how to train recurrent neural networks in tasks like those used to train animals in neuroscience laboratories, and how computations emerge in the trained networks. Surprisingly, artificial networks and real brains can use similar computational strategies.
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在人类中,感知意识促进了来自感官输入的快速识别和提取信息。这种意识在很大程度上取决于人类代理人如何与环境相互作用。在这项工作中,我们提出了主动神经生成编码,用于学习动作驱动的生成模型的计算框架,而不会在动态环境中反正出错误(Backprop)。具体而言,我们开发了一种智能代理,即使具有稀疏奖励,也可以从规划的认知理论中汲取灵感。我们展示了我们框架与深度Q学习竞争力的几个简单的控制问题。我们的代理的强劲表现提供了有希望的证据,即神经推断和学习的无背方法可以推动目标定向行为。
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Deep reinforcement learning is poised to revolutionise the field of AI and represents a step towards building autonomous systems with a higher level understanding of the visual world. Currently, deep learning is enabling reinforcement learning to scale to problems that were previously intractable, such as learning to play video games directly from pixels. Deep reinforcement learning algorithms are also applied to robotics, allowing control policies for robots to be learned directly from camera inputs in the real world. In this survey, we begin with an introduction to the general field of reinforcement learning, then progress to the main streams of value-based and policybased methods. Our survey will cover central algorithms in deep reinforcement learning, including the deep Q-network, trust region policy optimisation, and asynchronous advantage actor-critic. In parallel, we highlight the unique advantages of deep neural networks, focusing on visual understanding via reinforcement learning. To conclude, we describe several current areas of research within the field.
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在双替代强制选择任务中,先验知识可以提高性能,特别是在靠近心理物理阈值的操作时。例如,如果主题知道一个选择比另一个更有可能更有可能,则可以在证据疲软时使其选择。这些任务的常见假设是先前储存在神经活动中。在这里,我们提出了一个不同的假设:之前的储存在突触强度中。我们研究国际脑实验室任务,其中光栅出现在屏幕的右侧或左侧,鼠标必须移动一个轮子将光栅带到中心。相反,光栅通常是低的,这使得任务相对困难,并且光栅出现在右侧的现有概率是80%或20%,其(无罪)的约50试验块。我们将其模拟作为增强学习任务,使用前馈神经网络将状态映射到动作,并调整网络的权重以最大化奖励,通过策略梯度学习。我们的模型使用内部状态来存储对光栅和信心的估计,并遵循贝叶斯更新,并且可以在接合和脱离状态之间切换以模仿动物行为。该模型再现主要实验发现 - 在大约10个试验中,块开关后的对比度变化的心理曲线。此外,如在实验中所见,在我们的模型中,右侧块和左块中的神经元活动的差异很小 - 如果噪声约为2%,几乎不可能将块结构从单一试验中的活动中解码。难以测试的假设难以测试,但该技术应该在不遥远的未来中提供。
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强化学习(RL)和脑电脑接口(BCI)是过去十年一直在增长的两个领域。直到最近,这些字段彼此独立操作。随着对循环(HITL)应用的兴趣升高,RL算法已经适用于人类指导,从而产生互动强化学习(IRL)的子领域。相邻的,BCI应用一直很感兴趣在人机交互期间从神经活动中提取内在反馈。这两个想法通过将BCI集成到IRL框架中,将RL和BCI设置在碰撞过程中,通过将内在反馈可用于帮助培训代理商来帮助框架。这种交叉点被称为内在的IRL。为了进一步帮助,促进BCI和IRL的更深层次,我们对内在IRILL的审查有着重点在于其母体领域的反馈驱动的IRL,同时还提供有关有效性,挑战和未来研究方向的讨论。
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AI的一个关键挑战是构建体现的系统,该系统在动态变化的环境中运行。此类系统必须适应更改任务上下文并持续学习。虽然标准的深度学习系统实现了最先进的静态基准的结果,但它们通常在动态方案中挣扎。在这些设置中,来自多个上下文的错误信号可能会彼此干扰,最终导致称为灾难性遗忘的现象。在本文中,我们将生物学启发的架构调查为对这些问题的解决方案。具体而言,我们表明树突和局部抑制系统的生物物理特性使网络能够以特定于上下文的方式动态限制和路由信息。我们的主要贡献如下。首先,我们提出了一种新颖的人工神经网络架构,该架构将活跃的枝形和稀疏表示融入了标准的深度学习框架中。接下来,我们在需要任务的适应性的两个单独的基准上研究这种架构的性能:Meta-World,一个机器人代理必须学习同时解决各种操纵任务的多任务强化学习环境;和一个持续的学习基准,其中模型的预测任务在整个训练中都会发生变化。对两个基准的分析演示了重叠但不同和稀疏的子网的出现,允许系统流动地使用最小的遗忘。我们的神经实现标志在单一架构上第一次在多任务和持续学习设置上取得了竞争力。我们的研究揭示了神经元的生物学特性如何通知深度学习系统,以解决通常不可能对传统ANN来解决的动态情景。
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We adapt the ideas underlying the success of Deep Q-Learning to the continuous action domain. We present an actor-critic, model-free algorithm based on the deterministic policy gradient that can operate over continuous action spaces. Using the same learning algorithm, network architecture and hyper-parameters, our algorithm robustly solves more than 20 simulated physics tasks, including classic problems such as cartpole swing-up, dexterous manipulation, legged locomotion and car driving. Our algorithm is able to find policies whose performance is competitive with those found by a planning algorithm with full access to the dynamics of the domain and its derivatives. We further demonstrate that for many of the tasks the algorithm can learn policies "end-to-end": directly from raw pixel inputs.
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深度强化学习(RL)导致了许多最近和开创性的进步。但是,这些进步通常以培训的基础体系结构的规模增加以及用于训练它们的RL算法的复杂性提高,而均以增加规模的成本。这些增长反过来又使研究人员更难迅速原型新想法或复制已发表的RL算法。为了解决这些问题,这项工作描述了ACME,这是一个用于构建新型RL算法的框架,这些框架是专门设计的,用于启用使用简单的模块化组件构建的代理,这些组件可以在各种执行范围内使用。尽管ACME的主要目标是为算法开发提供一个框架,但第二个目标是提供重要或最先进算法的简单参考实现。这些实现既是对我们的设计决策的验证,也是对RL研究中可重复性的重要贡献。在这项工作中,我们描述了ACME内部做出的主要设计决策,并提供了有关如何使用其组件来实施各种算法的进一步详细信息。我们的实验为许多常见和最先进的算法提供了基准,并显示了如何为更大且更复杂的环境扩展这些算法。这突出了ACME的主要优点之一,即它可用于实现大型,分布式的RL算法,这些算法可以以较大的尺度运行,同时仍保持该实现的固有可读性。这项工作提出了第二篇文章的版本,恰好与模块化的增加相吻合,对离线,模仿和从演示算法学习以及作为ACME的一部分实现的各种新代理。
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We propose a conceptually simple and lightweight framework for deep reinforcement learning that uses asynchronous gradient descent for optimization of deep neural network controllers. We present asynchronous variants of four standard reinforcement learning algorithms and show that parallel actor-learners have a stabilizing effect on training allowing all four methods to successfully train neural network controllers. The best performing method, an asynchronous variant of actor-critic, surpasses the current state-of-the-art on the Atari domain while training for half the time on a single multi-core CPU instead of a GPU. Furthermore, we show that asynchronous actor-critic succeeds on a wide variety of continuous motor control problems as well as on a new task of navigating random 3D mazes using a visual input.
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This work is an exploratory research concerned with determining in what way reinforcement learning can be used to predict optimal PID parameters for a robot designed for apple harvest. To study this, an algorithm called Advantage Actor Critic (A2C) is implemented on a simulated robot arm. The simulation primarily relies on the ROS framework. Experiments for tuning one actuator at a time and two actuators a a time are run, which both show that the model is able to predict PID gains that perform better than the set baseline. In addition, it is studied if the model is able to predict PID parameters based on where an apple is located. Initial tests show that the model is indeed able to adapt its predictions to apple locations, making it an adaptive controller.
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Adequately assigning credit to actions for future outcomes based on their contributions is a long-standing open challenge in Reinforcement Learning. The assumptions of the most commonly used credit assignment method are disadvantageous in tasks where the effects of decisions are not immediately evident. Furthermore, this method can only evaluate actions that have been selected by the agent, making it highly inefficient. Still, no alternative methods have been widely adopted in the field. Hindsight Credit Assignment is a promising, but still unexplored candidate, which aims to solve the problems of both long-term and counterfactual credit assignment. In this thesis, we empirically investigate Hindsight Credit Assignment to identify its main benefits, and key points to improve. Then, we apply it to factored state representations, and in particular to state representations based on the causal structure of the environment. In this setting, we propose a variant of Hindsight Credit Assignment that effectively exploits a given causal structure. We show that our modification greatly decreases the workload of Hindsight Credit Assignment, making it more efficient and enabling it to outperform the baseline credit assignment method on various tasks. This opens the way to other methods based on given or learned causal structures.
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We present temporally layered architecture (TLA), a biologically inspired system for temporally adaptive distributed control. TLA layers a fast and a slow controller together to achieve temporal abstraction that allows each layer to focus on a different time-scale. Our design is biologically inspired and draws on the architecture of the human brain which executes actions at different timescales depending on the environment's demands. Such distributed control design is widespread across biological systems because it increases survivability and accuracy in certain and uncertain environments. We demonstrate that TLA can provide many advantages over existing approaches, including persistent exploration, adaptive control, explainable temporal behavior, compute efficiency and distributed control. We present two different algorithms for training TLA: (a) Closed-loop control, where the fast controller is trained over a pre-trained slow controller, allowing better exploration for the fast controller and closed-loop control where the fast controller decides whether to "act-or-not" at each timestep; and (b) Partially open loop control, where the slow controller is trained over a pre-trained fast controller, allowing for open loop-control where the slow controller picks a temporally extended action or defers the next n-actions to the fast controller. We evaluated our method on a suite of continuous control tasks and demonstrate the advantages of TLA over several strong baselines.
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设计加固学习(RL)代理通常是一个艰难的过程,需要大量的设计迭代。由于多种原因,学习可能会失败,并且标准RL方法提供的工具太少,无法洞悉确切原因。在本文中,我们展示了如何将价值分解整合到一类广泛的参与者批评算法中,并使用它来协助迭代代理设计过程。价值分解将奖励函数分为不同的组件,并学习每个组件的价值估计值。这些价值估计提供了对代理商的学习和决策过程的见解,并使新的培训方法可以减轻常见问题。作为演示,我们介绍了SAC-D,这是一种适合价值分解的软角色批评(SAC)的变体。 SAC-D保持与SAC相似的性能,同时学习一组更大的价值预测。我们还介绍了基于分解的工具来利用此信息,包括新的奖励影响指标,该指标衡量了每个奖励组件对代理决策的影响。使用这些工具,我们提供了分解用于识别和解决环境和代理设计问题的几种证明。价值分解广泛适用,易于将其纳入现有算法和工作流程中,使其成为RL从业人员的工具箱中的强大工具。
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Deep Reinforcement Learning is emerging as a promising approach for the continuous control task of robotic arm movement. However, the challenges of learning robust and versatile control capabilities are still far from being resolved for real-world applications, mainly because of two common issues of this learning paradigm: the exploration strategy and the slow learning speed, sometimes known as "the curse of dimensionality". This work aims at exploring and assessing the advantages of the application of Quantum Computing to one of the state-of-art Reinforcement Learning techniques for continuous control - namely Soft Actor-Critic. Specifically, the performance of a Variational Quantum Soft Actor-Critic on the movement of a virtual robotic arm has been investigated by means of digital simulations of quantum circuits. A quantum advantage over the classical algorithm has been found in terms of a significant decrease in the amount of required parameters for satisfactory model training, paving the way for further promising developments.
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由于数据量增加,金融业的快速变化已经彻底改变了数据处理和数据分析的技术,并带来了新的理论和计算挑战。与古典随机控制理论和解决财务决策问题的其他分析方法相比,解决模型假设的财务决策问题,强化学习(RL)的新发展能够充分利用具有更少模型假设的大量财务数据并改善复杂的金融环境中的决策。该调查纸目的旨在审查最近的资金途径的发展和使用RL方法。我们介绍了马尔可夫决策过程,这是许多常用的RL方法的设置。然后引入各种算法,重点介绍不需要任何模型假设的基于价值和基于策略的方法。连接是用神经网络进行的,以扩展框架以包含深的RL算法。我们的调查通过讨论了这些RL算法在金融中各种决策问题中的应用,包括最佳执行,投资组合优化,期权定价和对冲,市场制作,智能订单路由和Robo-Awaring。
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In this paper we consider deterministic policy gradient algorithms for reinforcement learning with continuous actions. The deterministic policy gradient has a particularly appealing form: it is the expected gradient of the action-value function. This simple form means that the deterministic policy gradient can be estimated much more efficiently than the usual stochastic policy gradient. To ensure adequate exploration, we introduce an off-policy actor-critic algorithm that learns a deterministic target policy from an exploratory behaviour policy. We demonstrate that deterministic policy gradient algorithms can significantly outperform their stochastic counterparts in high-dimensional action spaces.
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从意外的外部扰动中恢复的能力是双模型运动的基本机动技能。有效的答复包括不仅可以恢复平衡并保持稳定性的能力,而且在平衡恢复物质不可行时,也可以保证安全的方式。对于与双式运动有关的机器人,例如人形机器人和辅助机器人设备,可帮助人类行走,设计能够提供这种稳定性和安全性的控制器可以防止机器人损坏或防止伤害相关的医疗费用。这是一个具有挑战性的任务,因为它涉及用触点产生高维,非线性和致动系统的高动态运动。尽管使用基于模型和优化方法的前进方面,但诸如广泛领域知识的要求,诸如较大的计算时间和有限的动态变化的鲁棒性仍然会使这个打开问题。在本文中,为了解决这些问题,我们开发基于学习的算法,能够为两种不同的机器人合成推送恢复控制政策:人形机器人和有助于双模型运动的辅助机器人设备。我们的工作可以分为两个密切相关的指示:1)学习人形机器人的安全下降和预防策略,2)使用机器人辅助装置学习人类的预防策略。为实现这一目标,我们介绍了一套深度加强学习(DRL)算法,以学习使用这些机器人时提高安全性的控制策略。
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一种被称为优先体验重播(PER)的广泛研究的深钢筋学习(RL)技术使代理可以从与其时间差异(TD)误差成正比的过渡中学习。尽管已经表明,PER是离散作用域中深度RL方法总体性能的最关键组成部分之一,但许多经验研究表明,在连续控制中,它的表现非常低于参与者 - 批评算法。从理论上讲,我们表明,无法有效地通过具有较大TD错误的过渡对演员网络进行训练。结果,在Q网络下计算的近似策略梯度与在最佳Q功能下计算的实际梯度不同。在此激励的基础上,我们引入了一种新颖的经验重播抽样框架,用于演员批评方法,该框架还认为稳定性和最新发现的问题是Per的经验表现不佳。引入的算法提出了对演员和评论家网络的有效和高效培训的改进的新分支。一系列广泛的实验验证了我们的理论主张,并证明了引入的方法显着优于竞争方法,并获得了与标准的非政策参与者 - 批评算法相比,获得最先进的结果。
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