延迟在迅速变化的环境中运行的自主系统的危害安全性,例如在自动驾驶和高速赛车方面的交通参与者的非确定性。不幸的是,在传统的控制器设计或在物理世界中部署之前,通常不考虑延迟。在本文中,从非线性优化到运动计划和控制以及执行器引起的其他不可避免的延迟的计算延迟被系统地和统一解决。为了处理所有这些延迟,在我们的框架中:1)我们提出了一种新的过滤方法,而没有事先了解动态和干扰分布的知识,以适应,安全地估算时间变化的计算延迟; 2)我们为转向延迟建模驱动动力学; 3)所有约束优化均在强大的管模型预测控制器中实现。对于应用的优点,我们证明我们的方法适合自动驾驶和自动赛车。我们的方法是独立延迟补偿控制器的新型设计。此外,在假设无延迟作为主要控制器的学习控制器的情况下,我们的方法是主要控制器的安全保护器。
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对于自动驾驶汽车而言,遍历交叉点是一个具有挑战性的问题,尤其是当交叉路口没有交通控制时。最近,由于其成功处理自动驾驶任务,深厚的强化学习受到了广泛的关注。在这项工作中,我们解决了使用新颖的课程进行深入增强学习的问题的问题。拟议的课程导致:1)与未经课程训练的代理人相比,增强剂学习代理的更快的训练过程和2)表现更好。我们的主要贡献是两个方面:1)提供一个独特的课程,用于训练深入的强化学习者,2)显示了所提出的课程在未信号的交叉遍历任务中的应用。该框架期望自动驾驶汽车的感知系统对周围环境进行了处理。我们在Comonroad运动计划模拟器中测试我们的TTTERTIONS和四向交集的方法。
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本文介绍了一个新颖的社会偏好意识分散的安全控制框架,以解决避免多机构碰撞的责任分配问题。考虑到代理不一定会以对称方式进行合作,本文着重于具有不同合作水平的异质代理之间的半合作行为。利用社会价值取向(SVO)来量化个人自私的思想,我们提出了一个新颖的责任相关社会价值取向(R-SVO)的新颖概念,以表达成对代理之间的预期相对社会含义。这用于根据相应的责任份额来重新定义每个代理商的社会偏好或个性,以促进协调方案,例如所有代理商以不对称方式互动的半合件碰撞避免。通过通过拟议的本地成对责任权重纳入这种相对的社会影响,我们为个人代理人开发了与责任相关的控制屏障功能的安全控制框架,并通过正式可证明的安全保证可以实现多代理碰撞的避免。提供了模拟来证明在多个多代理导航任务中所提出的框架的有效性和效率,例如位置交换游戏,自动驾驶汽车公路公路坡道合并方案以及圆形交换游戏。
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随着使用复杂非线性优化但计算资源有限的经济实惠的自动驾驶车辆,计算时间成为关注问题。其他因素,如执行器动力学和执行器命令处理成本也不可避免地导致延迟。在高速场景中,这些延迟对于车辆的安全至关重要。最近的作品将这些延迟单独考虑,但没有在自动驾驶的背景下统一它们。此外,最近的作品不恰当地考虑计算时间作为恒定或大的上限,这使得控制较少响应或过保守。要处理所有这些延迟,我们通过1)统一的框架,使用鲁棒管模型预测控制,3)使用新型Adaptive Kalman滤波器,无需假定已知的过程模型和噪声协方差,这使得控制器安全尽量减少保守性。在一次性的情况下,我们的方法可以作为独立控制器;在其他手上,我们的方法为高级控制器提供了一个安全防护装置,这不拖延。这可以用于在部署在简单环境中培训的黑匣子学习的控制器时补偿SIM-TO-REAL间隙,而不考虑实际车辆系统的延迟。
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Variational autoencoders model high-dimensional data by positing low-dimensional latent variables that are mapped through a flexible distribution parametrized by a neural network. Unfortunately, variational autoencoders often suffer from posterior collapse: the posterior of the latent variables is equal to its prior, rendering the variational autoencoder useless as a means to produce meaningful representations. Existing approaches to posterior collapse often attribute it to the use of neural networks or optimization issues due to variational approximation. In this paper, we consider posterior collapse as a problem of latent variable non-identifiability. We prove that the posterior collapses if and only if the latent variables are non-identifiable in the generative model. This fact implies that posterior collapse is not a phenomenon specific to the use of flexible distributions or approximate inference. Rather, it can occur in classical probabilistic models even with exact inference, which we also demonstrate. Based on these results, we propose a class of latent-identifiable variational autoencoders, deep generative models which enforce identifiability without sacrificing flexibility. This model class resolves the problem of latent variable non-identifiability by leveraging bijective Brenier maps and parameterizing them with input convex neural networks, without special variational inference objectives or optimization tricks. Across synthetic and real datasets, latent-identifiable variational autoencoders outperform existing methods in mitigating posterior collapse and providing meaningful representations of the data.
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With water quality management processes, identifying and interpreting relationships between features, such as location and weather variable tuples, and water quality variables, such as levels of bacteria, is key to gaining insights and identifying areas where interventions should be made. There is a need for a search process to identify the locations and types of phenomena that are influencing water quality and a need to explain why the quality is being affected and which factors are most relevant. This paper addresses both of these issues through the development of a process for collecting data for features that represent a variety of variables over a spatial region, which are used for training and inference, and analysing the performance of the features using the model and Shapley values. Shapley values originated in cooperative game theory and can be used to aid in the interpretation of machine learning results. Evaluations are performed using several machine learning algorithms and water quality data from the Dublin Grand Canal basin.
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Prior work has looked at applying reinforcement learning and imitation learning approaches to autonomous driving scenarios, but either the safety or the efficiency of the algorithm is compromised. With the use of control barrier functions embedded into the reinforcement learning policy, we arrive at safe policies to optimize the performance of the autonomous driving vehicle. However, control barrier functions need a good approximation of the model of the car. We use probabilistic control barrier functions as an estimate of the model uncertainty. The algorithm is implemented as an online version in the CARLA (Dosovitskiy et al., 2017) Simulator and as an offline version on a dataset extracted from the NGSIM Database. The proposed algorithm is not just a safe ramp merging algorithm but a safe autonomous driving algorithm applied to address ramp merging on highways.
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Recent work in large language modeling (LLMs) has used fine-tuning to align outputs with the preferences of a prototypical user. This work assumes that human preferences are static and homogeneous across individuals, so that aligning to a a single "generic" user will confer more general alignment. Here, we embrace the heterogeneity of human preferences to consider a different challenge: how might a machine help people with diverse views find agreement? We fine-tune a 70 billion parameter LLM to generate statements that maximize the expected approval for a group of people with potentially diverse opinions. Human participants provide written opinions on thousands of questions touching on moral and political issues (e.g., "should we raise taxes on the rich?"), and rate the LLM's generated candidate consensus statements for agreement and quality. A reward model is then trained to predict individual preferences, enabling it to quantify and rank consensus statements in terms of their appeal to the overall group, defined according to different aggregation (social welfare) functions. The model produces consensus statements that are preferred by human users over those from prompted LLMs (>70%) and significantly outperforms a tight fine-tuned baseline that lacks the final ranking step. Further, our best model's consensus statements are preferred over the best human-generated opinions (>65%). We find that when we silently constructed consensus statements from only a subset of group members, those who were excluded were more likely to dissent, revealing the sensitivity of the consensus to individual contributions. These results highlight the potential to use LLMs to help groups of humans align their values with one another.
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Large language models (LLMs) have been shown to be able to perform new tasks based on a few demonstrations or natural language instructions. While these capabilities have led to widespread adoption, most LLMs are developed by resource-rich organizations and are frequently kept from the public. As a step towards democratizing this powerful technology, we present BLOOM, a 176B-parameter open-access language model designed and built thanks to a collaboration of hundreds of researchers. BLOOM is a decoder-only Transformer language model that was trained on the ROOTS corpus, a dataset comprising hundreds of sources in 46 natural and 13 programming languages (59 in total). We find that BLOOM achieves competitive performance on a wide variety of benchmarks, with stronger results after undergoing multitask prompted finetuning. To facilitate future research and applications using LLMs, we publicly release our models and code under the Responsible AI License.
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Manual prescription of the field of view (FOV) by MRI technologists is variable and prolongs the scanning process. Often, the FOV is too large or crops critical anatomy. We propose a deep-learning framework, trained by radiologists' supervision, for automating FOV prescription. An intra-stack shared feature extraction network and an attention network are used to process a stack of 2D image inputs to generate output scalars defining the location of a rectangular region of interest (ROI). The attention mechanism is used to make the model focus on the small number of informative slices in a stack. Then the smallest FOV that makes the neural network predicted ROI free of aliasing is calculated by an algebraic operation derived from MR sampling theory. We retrospectively collected 595 cases between February 2018 and February 2022. The framework's performance is examined quantitatively with intersection over union (IoU) and pixel error on position, and qualitatively with a reader study. We use the t-test for comparing quantitative results from all models and a radiologist. The proposed model achieves an average IoU of 0.867 and average ROI position error of 9.06 out of 512 pixels on 80 test cases, significantly better (P<0.05) than two baseline models and not significantly different from a radiologist (P>0.12). Finally, the FOV given by the proposed framework achieves an acceptance rate of 92% from an experienced radiologist.
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