Abstract-In cooperative multiagent systems, agents interact to solve tasks. Global dynamics of multiagent teams result from local agent interactions, and are complex and difficult to predict. Evolutionary computation has proven a promising approach to the design of such teams. The majority of current studies use teams composed of agents with identical control rules ("genetically homogeneous teams") and select behavior at the team level ("team-level selection"). Here we extend current approaches to include four combinations of genetic team composition and level of selection. We compare the performance of genetically homogeneous teams evolved with individual-level selection, genetically homogeneous teams evolved with team-level selection, genetically heterogeneous teams evolved with individual-level selection, and genetically heterogeneous teams evolved with team-level selection. We use a simulated foraging task to show that the optimal combination depends on the amount of cooperation required by the task. Accordingly, we distinguish between three types of cooperative tasks and suggest guidelines for the optimal choice of genetic team composition and level of selection.
Abstract-In this paper we present the design and implementation of Rapyuta1 , an open source cloud robotics platform. Rapyuta helps robots to offload heavy computation by providing secured customizable computing environments in the cloud. The computing environments also allow the robots to easily access the RoboEarth knowledge repository. Furthermore, these computing environments are tightly interconnected, paving the way for deployment of robotic teams. We also describe three typical use cases, some benchmarking and performance results, and two proof-of-concept demonstrations.Note to Practitioners-Rapyuta allows to outsource some or all of a robot's onboard computational processes to a commercial data center. Its main difference to other, similar frameworks like the Google App Engine is that it is specifically tailored towards multi-process high-bandwidth robotics applications/middlewares and provides a well documented open source implementation that can be modified to cover a large variety of robotic scenarios. Rapyuta supports the outsourcing of almost all of the current 3000+ ROS packages out of the box and is easily extensible to other robotic middleware. A pre-installed Amazon Machine Image (AMI) is provided that allows to launch Rapyuta in any of Amazon's data center within minutes. Once launched, robots can authenticate themselves to Rapyuta, create one or more secured computational environments in the cloud, and launch the desired nodes/processes. The computing environments can also be arbitrarily connected to build parallel computing architectures on the fly. The WebSocket-based communication protocol, which provides synchronous and asynchronous communication mechanisms, allows not only ROS based robots, but also browsers and mobiles phones to connect to the ecosystem. Rapyuta's computing environments are private, secure, and optimized for data throughput. However, its performance is in large part determined by the latency and quality of the network connection and the performance of the data center. Optimizing performance under these constraints is typically highly application specific. The paper illustrates an example of performance optimization in a collaborative real-time 3D mapping application. Other target applications include collaborative 3D mapping, task/grasp planning, object recognition, localization, and teleoperation, among others.
Abstract-This paper presents an architecture, protocol, and parallel algorithms for collaborative 3D mapping in the cloud with low-cost robots. The robots run a dense visual odometry algorithm on a smartphone-class processor. Key-frames from the visual odometry are sent to the cloud for parallel optimization and merging with maps produced by other robots. After optimization the cloud pushes the updated poses of the local key-frames back to the robots. All processes are managed by Rapyuta, a cloud robotics framework that runs in a commercial data center. The paper includes qualitative visualization of collaboratively built maps, as well as quantitative evaluation of localization accuracy, bandwidth usage, processing speeds, and map storage.Note to Practitioners-This paper presents an architecture for cloud-based collaborative 3D mapping with low-cost robots. The low-cost robots used in this work consist mainly of a mobile base, a smart phone class processor, an RGB-D sensor and a wireless interface. Each robot runs its own visual odometry algorithm, which estimates the pose of the robot using the color and the depth frames (images) from the RGB-D sensor. The dense visual odometry algorithm presented herein uses no image features and requires no specialized hardware. In addition to pose estimation, the visual odometry algorithm also produces key-frames, which is a subset of frames that in a way summarizes the motion of the robot. These key-frames are sent to the cloud for further optimization and merging with the key-frames produced by other robots. By sending only the key-frames (instead of all the frames produced by the sensor), bandwidth requirements are significantly reduced. Each robot is connected to the cloud infrastructure using a WebSocket-based bidirectional full duplex communication channel. The cloud infrastructure is provided using Rapyuta, a Platform-as-a-Service framework for building scalable cloud robotics applications. The key-frame pose optimization and the merging processes are parallelized in order to make them scalable. The updated key-frame poses are eventually sent back to the robot to improve its localization accuracy. In addition to describing the architecture and the design choices, the paper provides qualitative and quantitative evaluations of the integrated system.
Between Zintl and Wiberg: The tetrahedral silicon cluster [(MesCu)2Si4]4− was obtained from the reaction of K6Rb6Si17 and MesCu (Mes=2,4,6‐Me3C6H2) in liquid ammonia. Through stabilization with transition metal fragments, highly charged silicon clusters can thus be transferred and handled in solution.
Abstract-In this paper we present the design and implementation of Rapyuta 1 , the RoboEarth Cloud Engine. Rapyuta is an open source Platform-as-a-Service (PaaS) framework designed specifically for robotics applications. Rapyuta helps robots to offload heavy computation by providing secured customizable computing environments in the cloud. The computing environments also allow robots to easily access the RoboEarth knowledge repository. Furthermore, these computing environments are tightly interconnected, paving the way for deployment of robotic teams. We also describe specific use case configurations and present some performance results.
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