Computation offloading has been widely recognized as an effective way to promote the capabilities of resource‐constrained mobile devices. Recent years have seen a renewal of the importance of this technology in the emerging field of mobile robots, supporting resource‐intensive robot applications. However, cooperating to solve complex tasks in the physical world, which is a significant feature of a robot swarm compared to traditional mobile computing devices, has not received in‐depth attention in research concerned with traditional computation offloading. In this study, we propose an approach named cooperation offloading, which offloads the intensive communication among robots as well as the computation for compute‐intensive and data‐intensive tasks. We analyze the performance gain of cooperation offloading by formalizing multirobot cooperative models; in addition, we study offloading decisions. Based on this approach, we design a cloud robotic framework named Cloudroid Swarm and develop several QoS‐aware mechanisms to provide a general solution to cooperation offloading with QoS assurance in multirobot cooperative scenes. We implement Cloudroid Swarm to transparently migrate multirobot applications to cloud servers without any code modification. We evaluate our framework using three different multirobot cooperative applications. Our results show that Cloudroid Swarm can be applied to various robotic applications and real‐world environments and bring significant benefits in terms of both network optimization and task performance. Besides, our framework has good scalability and can do support as many as 256 robot entities simultaneously.

Computation offloading has been widely recognized as an effective way to promote the capabilities of resource-constrained mobile devices. The past years have seen a renewed importance of this technology in the emerging field of mobile robots. However, a significant feature of robots compared to traditional mobile computing devices (e.g. smartphones) is that they must collaborate to solve complex tasks in the physical world in many cases, which implies intensive data exchange among the robot peers. This characteristic has not been dealt with in-depth in traditional computation offloading research. In this paper, we propose an approach called Cooperative Offloading, which takes into account the cooperation among mobile devices as well as the communication it brings in computation offloading. Firstly, we propose the offloading decision approach that deals with offloading from a set of robots that cooperate to finish a specific task. Secondly, we present a set of mechanisms to optimize the data transfer path on network topology in multi-robot applications, which can significantly reduce the bandwidth consumption of the robot wireless network. Based on the cooperative offloading approach, we realized a cloud robotics framework called Cloudroid Swarm. Evaluations based on real-life applications have shown that Cloudroid Swarm brings more than five times performance promotion compared to the setup without offloading or with individual computation offloading.

In the past decade, multi-robot simultaneous localization and mapping (SLAM) has been widely studied. However, the problem of collaborative SLAM with a large number of robots, such as dozens of robots, is far from being well solved. The challenges stem from not only the computation complexity in large-scale map merging but also the inefficiency to enable the parallel computing in this process, which is indispensable for us to make avail of the frontier of computing technology such as powerful cloud infrastructure. To effectively address these challenges, especially the latter one, we propose a scalable and real-time multi-robot visual SLAM framework based on the cloud robotic paradigm. The prominent feature of our framework is that it can distribute the SLAM process to multiple computing hosts in a cluster, which enables map building in parallel. To eliminate the bottleneck from data sharing between different sub-tasks, we also introduce diversified messaging pattern for various messaging scenarios, as well as the consistency policies for map data. The evaluations on the prototype of our framework, have shown that our method can do support as many as 256 robot entities simultaneously, without any compromising on the precision of poses estimation and map building.

We present an unsupervised learning framework for the task of monocular depth and camera motion estimation from video sequences. In common with recent work, we use an unsupervised end-to-end learning method, requiring monocular video sequences for training. What makes the difference is, our approach not only uses image reconstruction as the supervisory signal but also exploits the pose estimation method which was used in traditional SLAM approach to enhance the supervisory signal and add training constraints. In pose estimation, a continuous frame window is set to construct the pose graph. Our method uses single-view depth and multi-view pose networks, with a loss based on reconstructing nearby images to the target using the predicted depth and pose. During training, the networks are thus coupled by the loss but can be applied independently at test time. Our evaluation of experiments on the KITTI dataset proves the effectiveness of our method: 1) monocular depth performs superior to the supervised methods that use ground-truth depth data for training and the existing unsupervised learning method. Our method performs comparably with the supervised methods that use ground-truth pose data for training. 2) pose estimation performs almost the same compared to established SLAM systems under comparable input settings.

Many robotic tasks require heavy computation, which can easily exceed the robot's onboard computer capability. A promising solution to address this challenge is outsourcing thecomputation to the cloud. However, exploiting the potential ofcloud resources in robotic software is difficult, because it in-volves complex code modification and extensive (re)configurationprocedures. Moreover, quality of service (QoS) such as timeliness, which is critical to robot's behavior, have to be considered. Inthis paper, we propose a transparent and QoS-aware softwareframework called Cloudroid for cloud robotic applications. Thisframework supports direct deployment of existing robotic soft-ware packages to the cloud, transparently transforming theminto Internet-accessible cloud services. And with the automati-cally generated service stubs, robotic applications can outsourcetheir computation to the cloud without any code modification. Furthermore, the robot and the cloud can cooperate to maintainthe specific QoS property such as request response time, evenin a highly dynamic and resource-competitive environment. Weevaluated Cloudroid based on a group of typical robotic scenariosand a set of software packages widely adopted in real-worldrobot practices. Results show that robots capability can beenhanced significantly without code modification and specific QoSobjectives can be guaranteed. In certain tasks, the "cloud + robot" setup shows improved performance in orders of magnitudecompared with the robot native setup.

Internet-based virtual computing environment (iVCE) has been proposed to combine data centers and other kinds of computing resources on the Internet to provide efficient and economical services. Virtual machines (VMs) have been widely used in iVCE to isolate different users/jobs and ensure trustworthiness, but traditionally VMs require a long period of time for booting, which cannot meet the requirement of iVCE’s large-scale and highly dynamic applications. To address this problem, in this paper we design and implement VirtMan, a fast booting system for a large number of virtual machines in iVCE. VirtMan uses the Linux Small Computer System Interface (SCSI) target to remotely mount to the source image in a scalable hierarchy, and leverages the homogeneity of a set of VMs to transfer only necessary image data at runtime. We have implemented VirtMan both as a standalone system and for OpenStack. In our 100-server testbed, VirtMan boots up 1000 VMs (with a 15 GB image of Windows Server 2008) on 100 physical servers in less than 120 s, which is three orders of magnitude lower than current public clouds.

In IaaS cloud environments, peak memory demand caused by hotspot applications in Virtual Machine (VM) often results in performance degradation within and outside of this VM. Some solutions such as host swapping and ballooning for memory consolidation and overcommitment have been proposed. These solutions, however, have no help for addressing guest swapping issues inside VM. Even though host holds sufficient memory pages, guest OS is unable to utilize free pages in host directly due to the semantic gap between VMM and it. Our goal is to alleviate the performance degradation by decreasing disk I/O operations generated by guest swapping. Based on the insight analysis of behavioral features of guest swapping, we design HybridSwap, a distributed scalable framework which organize surplus memory in all hosts within data center into virtual pools for swapping. This framework builds up a synthetic swapping mechanism in a peer-to-peer way, which VM can adaptively choose suitable pools for swapping. We implement the prototype of HybridSwap and evaluate it with different benchmarks. The results demonstrate that our solution has the ability to promote the guest swapping efficiency indeed. Even in some cases, it shows 2-5 times of performance promotion compared with the baseline setup.

Increasing Internet business and computing footprint motivate server consolidation in data centers. Through virtualization technology, server consolidation can reduce physical hosts and provide scalable services. However, the ineffective memory usage among multiple virtual machines (VMs) becomes the bottleneck in server consolidation environment. Because of inaccurate memory usage estimate and the lack of memory resource managements, there is much service performance degradation in data centers, even though they have occupied a large amount of memory. In order to improve this scenario, we first introduce VM's memory division view and VM's free memory division view. Based on them, we propose a hierarchal memory service mechanism. We have designed and implemented the corresponding memory scheduling algorithm to enhance memory efficiency and achieve service level agreement. The benchmark test results show that our implementation can save 30% physical memory with 1% to 5% performance degradation. Based on Xen virtualization platform and balloon driver technology, our works actually bring dramatic benefits to commercial cloud computing center which is providing more than 2,000 VMs' services to cloud computing users.