While reinforcement learning (RL) has become a more popular approach for robotics, designing sufficiently informative reward functions for complex tasks has proven to be extremely difficult due their inability to capture human intent and policy exploitation. Preference based RL algorithms seek to overcome these challenges by directly learning reward functions from human feedback. Unfortunately, prior work either requires an unreasonable number of queries implausible for any human to answer or overly restricts the class of reward functions to guarantee the elicitation of the most informative queries, resulting in models that are insufficiently expressive for realistic robotics tasks. Contrary to most works that focus on query selection to \emph{minimize} the amount of data required for learning reward functions, we take an opposite approach: \emph{expanding} the pool of available data by viewing human-in-the-loop RL through the more flexible lens of multi-task learning. Motivated by the success of meta-learning, we pre-train preference models on prior task data and quickly adapt them for new tasks using only a handful of queries. Empirically, we reduce the amount of online feedback needed to train manipulation policies in Meta-World by 20$\times$, and demonstrate the effectiveness of our method on a real Franka Panda Robot. Moreover, this reduction in query-complexity allows us to train robot policies from actual human users. Videos of our results and code can be found at https://sites.google.com/view/few-shot-preference-rl/home.

元强化学习（RL）方法可以使用比标准RL少的数据级的元培训策略，但元培训本身既昂贵又耗时。如果我们可以在离线数据上进行元训练，那么我们可以重复使用相同的静态数据集，该数据集将一次标记为不同任务的奖励，以在元测试时间适应各种新任务的元训练策略。尽管此功能将使Meta-RL成为现实使用的实用工具，但离线META-RL提出了除在线META-RL或标准离线RL设置之外的其他挑战。 Meta-RL学习了一种探索策略，该策略收集了用于适应的数据，并元培训策略迅速适应了新任务的数据。由于该策略是在固定的离线数据集上进行了元训练的，因此当适应学识渊博的勘探策略收集的数据时，它可能表现得不可预测，这与离线数据有系统地不同，从而导致分布变化。我们提出了一种混合脱机元元素算法，该算法使用带有奖励的脱机数据来进行自适应策略，然后收集其他无监督的在线数据，而无需任何奖励标签来桥接这一分配变化。通过不需要在线收集的奖励标签，此数据可以便宜得多。我们将我们的方法比较了在模拟机器人的运动和操纵任务上进行离线元rl的先前工作，并发现使用其他无监督的在线数据收集可以显着提高元训练政策的自适应能力，从而匹配完全在线的表现。在一系列具有挑战性的域上，需要对新任务进行概括。

强化学习（RL）需要访问刺激行为正确的行为的奖励功能，但这些都是非常难以指定复杂的任务。基于偏好RL提供了一种替代方案：用学习老师的偏好，而不用预先定义的奖励，从而克服与奖赏有关的工程关注的政策。然而，这是很难量化基于偏好-RL的进展，由于缺乏一个普遍采用的基准。在本文中，我们介绍了B-县：基准专为基于偏好-RL设计。这样的标杆的一个关键挑战是提供快速评估候选算法的能力，这使得依靠真正的人类输入的评价望而却步。与此同时，人类模拟输入作为给完美的喜好地面实况奖励功能是不现实的。 B-县通过一系列广泛的非理性的模拟教师缓解这一，并提出不仅仅是性能也为稳健性这些潜在的不合理性指标。我们用它来分析算法的设计选择，如选择信息查询，为国家的最先进的基于偏好的RL算法展示B-县的效用。我们希望B-县可以作为起点，以诚为本偏好研究RL更系统常见的。源代码可以在https://github.com/rll-research/B-Pref。

我们开发了一种新的持续元学习方法，以解决连续多任务学习中的挑战。在此设置中，代理商的目标是快速通过任何任务序列实现高奖励。先前的Meta-Creenifiltive学习算法已经表现出有希望加速收购新任务的结果。但是，他们需要在培训期间访问所有任务。除了简单地将过去的经验转移到新任务，我们的目标是设计学习学习的持续加强学习算法，使用他们以前任务的经验更快地学习新任务。我们介绍了一种新的方法，连续的元策略搜索（Comps），通过以增量方式，在序列中的每个任务上，通过序列的每个任务来消除此限制，而无需重新访问先前的任务。 Comps持续重复两个子程序：使用RL学习新任务，并使用RL的经验完全离线Meta学习，为后续任务学习做好准备。我们发现，在若干挑战性连续控制任务的旧序列上，Comps优于持续的持续学习和非政策元增强方法。

For an autonomous agent to fulfill a wide range of user-specified goals at test time, it must be able to learn broadly applicable and general-purpose skill repertoires. Furthermore, to provide the requisite level of generality, these skills must handle raw sensory input such as images. In this paper, we propose an algorithm that acquires such general-purpose skills by combining unsupervised representation learning and reinforcement learning of goal-conditioned policies. Since the particular goals that might be required at test-time are not known in advance, the agent performs a self-supervised "practice" phase where it imagines goals and attempts to achieve them. We learn a visual representation with three distinct purposes: sampling goals for self-supervised practice, providing a structured transformation of raw sensory inputs, and computing a reward signal for goal reaching. We also propose a retroactive goal relabeling scheme to further improve the sample-efficiency of our method. Our off-policy algorithm is efficient enough to learn policies that operate on raw image observations and goals for a real-world robotic system, and substantially outperforms prior techniques. * Equal contribution. Order was determined by coin flip.

Meta-Renifiltive学习（Meta-RL）已被证明是利用事先任务的经验，以便快速学习新的相关任务的成功框架，但是，当前的Meta-RL接近在稀疏奖励环境中学习的斗争。尽管现有的Meta-RL算法可以学习适应新的稀疏奖励任务的策略，但是使用手形奖励功能来学习实际适应策略，或者需要简单的环境，其中随机探索足以遇到稀疏奖励。在本文中，我们提出了对Meta-RL的后视抢购的制定，该rl抢购了在Meta培训期间的经验，以便能够使用稀疏奖励完全学习。我们展示了我们的方法在套件挑战稀疏奖励目标达到的环境中，以前需要密集的奖励，以便在Meta训练中解决。我们的方法使用真正的稀疏奖励功能来解决这些环境，性能与具有代理密集奖励功能的培训相当。

Poor sample efficiency continues to be the primary challenge for deployment of deep Reinforcement Learning (RL) algorithms for real-world applications, and in particular for visuo-motor control. Model-based RL has the potential to be highly sample efficient by concurrently learning a world model and using synthetic rollouts for planning and policy improvement. However, in practice, sample-efficient learning with model-based RL is bottlenecked by the exploration challenge. In this work, we find that leveraging just a handful of demonstrations can dramatically improve the sample-efficiency of model-based RL. Simply appending demonstrations to the interaction dataset, however, does not suffice. We identify key ingredients for leveraging demonstrations in model learning -- policy pretraining, targeted exploration, and oversampling of demonstration data -- which forms the three phases of our model-based RL framework. We empirically study three complex visuo-motor control domains and find that our method is 150%-250% more successful in completing sparse reward tasks compared to prior approaches in the low data regime (100K interaction steps, 5 demonstrations). Code and videos are available at: https://nicklashansen.github.io/modemrl

Meta-reinforcement learning algorithms can enable robots to acquire new skills much more quickly, by leveraging prior experience to learn how to learn. However, much of the current research on meta-reinforcement learning focuses on task distributions that are very narrow. For example, a commonly used meta-reinforcement learning benchmark uses different running velocities for a simulated robot as different tasks. When policies are meta-trained on such narrow task distributions, they cannot possibly generalize to more quickly acquire entirely new tasks. Therefore, if the aim of these methods is enable faster acquisition of entirely new behaviors, we must evaluate them on task distributions that are sufficiently broad to enable generalization to new behaviors. In this paper, we propose an open-source simulated benchmark for meta-reinforcement learning and multitask learning consisting of 50 distinct robotic manipulation tasks. Our aim is to make it possible to develop algorithms that generalize to accelerate the acquisition of entirely new, held-out tasks. We evaluate 7 state-of-the-art meta-reinforcement learning and multi-task learning algorithms on these tasks. Surprisingly, while each task and its variations (e.g., with different object positions) can be learned with reasonable success, these algorithms struggle to learn with multiple tasks at the same time, even with as few as ten distinct training tasks. Our analysis and open-source environments pave the way for future research in multi-task learning and meta-learning that can enable meaningful generalization, thereby unlocking the full potential of these methods. 1

强化学习（RL）算法有望为机器人系统实现自主技能获取。但是，实际上，现实世界中的机器人RL通常需要耗时的数据收集和频繁的人类干预来重置环境。此外，当部署超出知识的设置超出其学习的设置时，使用RL学到的机器人政策通常会失败。在这项工作中，我们研究了如何通过从先前看到的任务中收集的各种离线数据集的有效利用来应对这些挑战。当面对一项新任务时，我们的系统会适应以前学习的技能，以快速学习执行新任务并将环境返回到初始状态，从而有效地执行自己的环境重置。我们的经验结果表明，将先前的数据纳入机器人增强学习中可以实现自主学习，从而大大提高了学习的样本效率，并可以更好地概括。

无监督的表示学习的最新进展显着提高了模拟环境中培训强化学习政策的样本效率。但是，尚未看到针对实体强化学习的类似收益。在这项工作中，我们专注于从像素中启用数据有效的实体机器人学习。我们提出了有效的机器人学习（编码器）的对比前训练和数据增强，该方法利用数据增强和无监督的学习来从稀疏奖励中实现对实体ARM策略的样本效率培训。虽然对比预训练，数据增强，演示和强化学习不足以进行有效学习，但我们的主要贡献表明，这些不同技术的组合导致了一种简单而数据效率的方法。我们表明，只有10个示范，一个机器人手臂可以从像素中学习稀疏的奖励操纵策略，例如到达，拾取，移动，拉动大物体，翻转开关并在短短30分钟内打开抽屉现实世界训练时间。我们在项目网站上包括视频和代码：https：//sites.google.com/view/felfficited-robotic-manipulation/home

When robots learn reward functions using high capacity models that take raw state directly as input, they need to both learn a representation for what matters in the task -- the task ``features" -- as well as how to combine these features into a single objective. If they try to do both at once from input designed to teach the full reward function, it is easy to end up with a representation that contains spurious correlations in the data, which fails to generalize to new settings. Instead, our ultimate goal is to enable robots to identify and isolate the causal features that people actually care about and use when they represent states and behavior. Our idea is that we can tune into this representation by asking users what behaviors they consider similar: behaviors will be similar if the features that matter are similar, even if low-level behavior is different; conversely, behaviors will be different if even one of the features that matter differs. This, in turn, is what enables the robot to disambiguate between what needs to go into the representation versus what is spurious, as well as what aspects of behavior can be compressed together versus not. The notion of learning representations based on similarity has a nice parallel in contrastive learning, a self-supervised representation learning technique that maps visually similar data points to similar embeddings, where similarity is defined by a designer through data augmentation heuristics. By contrast, in order to learn the representations that people use, so we can learn their preferences and objectives, we use their definition of similarity. In simulation as well as in a user study, we show that learning through such similarity queries leads to representations that, while far from perfect, are indeed more generalizable than self-supervised and task-input alternatives.

有效的探索是深度强化学习的关键挑战。几种方法，例如行为先验，能够利用离线数据，以便在复杂任务上有效加速加强学习。但是，如果手动的任务与所证明的任务过度偏离，则此类方法的有效性是有限的。在我们的工作中，我们建议从离线数据中学习功能，这些功能由更加多样化的任务共享，例如动作与定向之间的相关性。因此，我们介绍了无国有先验，该先验直接在显示的轨迹中直接建模时间一致性，并且即使在对简单任务收集的数据进行培训时，也能够在复杂的任务中推动探索。此外，我们通过从政策和行动之前的概率混合物中动态采样动作，引入了一种新颖的集成方案，用于非政策强化学习中的动作研究。我们将我们的方法与强大的基线相提并论，并提供了经验证据，表明它可以在稀疏奖励环境下的长途持续控制任务中加速加强学习。

Exploration in environments with sparse rewards has been a persistent problem in reinforcement learning (RL). Many tasks are natural to specify with a sparse reward, and manually shaping a reward function can result in suboptimal performance. However, finding a non-zero reward is exponentially more difficult with increasing task horizon or action dimensionality. This puts many real-world tasks out of practical reach of RL methods. In this work, we use demonstrations to overcome the exploration problem and successfully learn to perform long-horizon, multi-step robotics tasks with continuous control such as stacking blocks with a robot arm. Our method, which builds on top of Deep Deterministic Policy Gradients and Hindsight Experience Replay, provides an order of magnitude of speedup over RL on simulated robotics tasks. It is simple to implement and makes only the additional assumption that we can collect a small set of demonstrations. Furthermore, our method is able to solve tasks not solvable by either RL or behavior cloning alone, and often ends up outperforming the demonstrator policy.

Adversarial imitation learning (AIL) has become a popular alternative to supervised imitation learning that reduces the distribution shift suffered by the latter. However, AIL requires effective exploration during an online reinforcement learning phase. In this work, we show that the standard, naive approach to exploration can manifest as a suboptimal local maximum if a policy learned with AIL sufficiently matches the expert distribution without fully learning the desired task. This can be particularly catastrophic for manipulation tasks, where the difference between an expert and a non-expert state-action pair is often subtle. We present Learning from Guided Play (LfGP), a framework in which we leverage expert demonstrations of multiple exploratory, auxiliary tasks in addition to a main task. The addition of these auxiliary tasks forces the agent to explore states and actions that standard AIL may learn to ignore. Additionally, this particular formulation allows for the reusability of expert data between main tasks. Our experimental results in a challenging multitask robotic manipulation domain indicate that LfGP significantly outperforms both AIL and behaviour cloning, while also being more expert sample efficient than these baselines. To explain this performance gap, we provide further analysis of a toy problem that highlights the coupling between a local maximum and poor exploration, and also visualize the differences between the learned models from AIL and LfGP.

有效的探索仍然是一个重要的挑战，这可以防止为许多物理系统部署加强学习。对于具有连续和高维状态和动作空间的系统尤其如此，例如机器人操纵器。挑战在稀疏奖励环境中强调，其中设计密集奖励设计所需的低级状态信息不可用。对手仿制学习（AIL）可以通过利用专家生成的最佳行为和基本上提供替代奖励信息的替代来部分克服这一屏障。不幸的是，专家示范的可用性并不一定能够改善代理商有效探索的能力，并且正如我们经常展现所在，可以导致效率低或停滞不前。我们从引导播放（LFGP）中展示了一个框架，其中我们利用了专家演示，除了主要任务，多个辅助任务。随后，使用修改的AIL过程来使用分层模型来学习每个任务奖励和策略，其中通过组合不同任务的调度程序强制对所有任务的探索。这提供了许多好处：具有挑战瓶颈转换的主要任务的学习效率得到改善，专家数据在任务之间可重复使用，并且通过重用学习辅助任务模型的传输学习成为可能。我们在一个具有挑战性的多任务机器人操纵域中的实验结果表明我们的方法有利地对监督模仿学习和最先进的AIL方法进行比较。代码可在https://github.com/utiasstars/lfgp获得。

实现人类水平的灵活性是机器人技术中的重要开放问题。但是，即使在婴儿级别，灵巧的手动操纵任务也是通过增强学习（RL）的挑战。困难在于高度的自由度和异质因素（例如手指关节）之间所需的合作。在这项研究中，我们提出了双人灵感手基准（BI-DEXHANDS），这是一种模拟器，涉及两只灵巧的手，其中包含数十只双人操纵任务和数千个目标对象。具体而言，根据认知科学文献，BI-DEXHANDS中的任务旨在匹配不同级别的人类运动技能。我们在ISSAC体育馆里建造了Bi-Dexhands；这可以实现高效的RL培训，仅在一个NVIDIA RTX 3090中达到30,000+ fps。我们在不同的设置下为流行的RL算法提供了全面的基准；这包括单代理/多代理RL，离线RL，多任务RL和META RL。我们的结果表明，PPO类型的上车算法可以掌握简单的操纵任务，该任务等效到48个月的人类婴儿（例如，捕获飞行的物体，打开瓶子），而多代理RL可以进一步帮助掌握掌握需要熟练的双人合作的操作（例如，举起锅，堆叠块）。尽管每个任务都取得了成功，但在获得多个操纵技能方面，现有的RL算法无法在大多数多任务和少量学习设置中工作，这需要从RL社区进行更实质性的发展。我们的项目通过https://github.com/pku-marl/dexteroushands开放。

人类可以利用先前的经验，并从少数示威活动中学习新颖的任务。与旨在通过更好的算法设计来快速适应的离线元强化学习相反，我们研究了建筑归纳偏见对少量学习能力的影响。我们提出了一个基于及时的决策变压器（提示-DT），该变压器利用了变压器体系结构和及时框架的顺序建模能力，以在离线RL中实现少量适应。我们设计了轨迹提示，其中包含少量演示的片段，并编码特定于任务的信息以指导策略生成。我们在五个Mujoco控制基准中进行的实验表明，提示-DT是一个强大的少数学习者，而没有对看不见的目标任务进行任何额外的填充。提示-DT的表现优于其变体和强大的元线RL基线，只有一个轨迹提示符只包含少量时间段。提示-DT也很健壮，可以提示长度更改并可以推广到分布（OOD）环境。

我们研究了从机器人交互的大型离线数据集学习一系列基于视觉的操纵任务的问题。为了实现这一目标，人类需要简单有效地将任务指定给机器人。目标图像是一种流行的任务规范形式，因为它们已经在机器人的观察空间接地。然而，目标图像也有许多缺点：它们对人类提供的不方便，它们可以通过提供导致稀疏奖励信号的所需行为，或者在非目标达到任务的情况下指定任务信息。自然语言为任务规范提供了一种方便而灵活的替代方案，而是随着机器人观察空间的接地语言挑战。为了可扩展地学习此基础，我们建议利用具有人群源语言标签的离线机器人数据集（包括高度最佳，自主收集的数据）。使用此数据，我们学习一个简单的分类器，该分类器预测状态的更改是否完成了语言指令。这提供了一种语言调节奖励函数，然后可以用于离线多任务RL。在我们的实验中，我们发现，在语言条件的操作任务中，我们的方法优于目标 - 图像规格和语言条件仿制技术超过25％，并且能够从自然语言中执行Visuomotor任务，例如“打开右抽屉“和”移动订书机“，在弗兰卡·埃米卡熊猫机器人上。

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。

元加强学习（META-RL）是一种方法，即从解决各种任务中获得的经验被蒸馏成元政策。当仅适应一个小（或仅一个）数量的步骤时，元派利赛能够在新的相关任务上近距离执行。但是，采用这种方法来解决现实世界中的问题的主要挑战是，它们通常与稀疏的奖励功能相关联，这些功能仅表示任务是部分或完全完成的。我们考虑到某些数据可能由亚最佳代理生成的情况，可用于每个任务。然后，我们使用示范（EMRLD）开发了一类名为“增强元RL”的算法，即使在训练过程中获得了次优的指导，也可以利用此信息。我们展示了EMRLD如何共同利用RL和在离线数据上进行监督学习，以生成一个显示单调性能改进的元数据。我们还开发了一个称为EMRLD-WS的温暖开始的变体，该变体对于亚最佳演示数据特别有效。最后，我们表明，在包括移动机器人在内的各种稀疏奖励环境中，我们的EMRLD算法显着优于现有方法。