AIRCC PUBLISHING CORPORATION
A Rapid Deployment Big Data Computing Platform For Cloud Robotics
Leigh Duggan1, James Dowzard2, Jayantha Katupitiya3, and Ka C. Chan4
1,2,3,4Department of Mechatronic Engineering, University of New South Wales, Australia
4Department of Computer Science and Information Technology, La Trobe University, Australia
The primary contribution of this research is the production of a general cloud robotics architecture that leverages the established and evolving big data technologies. Prior research in this area has not released all details of their deployed architectures, which prevents experimental results from being replicated and verified. By providing a general-purpose architecture, it is hoped that this framework will allow future research to build upon and begin to create a standardised platform, where research can be easily repeated, validated and compared.The secondary contribution is the critical evaluation of the design of cloud robotic architectures. Whilst prior research has demonstrated that cloud-based robotic processing is achievable via big data technologies, such research has not discussed the choice in design. With the ecosystem of big data technologies expanding in recent years, a review of the most relevant technologies for cloud robotics is appropriate to demonstrate and validate the proposed architectural design.
Cloud robotics, big data, OpenStack, Apache, ROS.
Cloud robotics possesses enormous potential for furthering the capabilities and applications of robots in existing and new challenging environments. The designed architecture detailed in this paper has the potential to dramatically change the affordability of features and capabilities currently available to high performance and expensive robots. Cloud robotics and cloud-based deployments of big data systems share similar objectives and features. The more established and mature big data frameworks have the potential to be leveraged by cloud robotics, which prior research has demonstrated through the implementation of cloud-based processing with such technologies.
Since the original Cloud Robotic framework of DAvinCi , few cloud robotic architectures have validated their choice of design, or explored the growing ecosystem of big data software and frameworks.
The objective of this research is to:
The approach to achieve this objective is to:
2. Related Work
The primary cloud robotic projects that have utilized aspects of big data include:
DAvinCi was a privately funded project in 2010, that utilised a cloud-based infrastructure to demonstrate the advantages of moving heavy computational processes such as SLAM and mapping to the cloud. The project utilised Robot Operating System (ROS) software for data collection from sensors and forwarding to the cloud architecture, and a Hadoop cluster to store and process this data with localisation and mapping algorithms. The project demonstrated the scalability of Hadoop, and its impact on the time to perform robotic algorithms .
2.2 Roboearth Platform
The RoboEarth Platform is a collection of software components that aims to create and facilitate the ‘World Wide Web for Robots’ . The platform’s aim was for robots to exchange their acquired data to enable robots to collectively learn from one another. Big data techniques are used to learn and extract useful information such as acquired data, and make this available to robots in RoboEarth’s online database. This database houses a variety of robot-centric information including software components, maps, and task knowledge and object recognition models. Such information can be used by a robot (and its hardware) to extend a robots sensing, reasoning and functionality. Rapyuta   is an open-source cloud computing component that creates a Platform-as-a-Service (PaaS) framework to move computational intensive activities from robots into the cloud. Each robot running Rapyuta creates a virtual container in the cloud that can be used to store data, to run computational intensive tasks, exchange information with other Rapyuta containers, and connect to the RoboEarth knowledge database .
2.3 Cloud Based Robot Grasping
The Cloud Based Robot Grasping project was developed to facilitate the sharing and learning of objects and grasping functions . The project allowed a robot to send a picture of an object to the cloud for processing, which would attempt to identify it within its database, returning the information on the item if found. This information allowed a robot to understand and perform the appropriate grasping manoeuvre, the results of which were stored in the cloud for future reference.
3. Design Justification
Whilst the introduction of big data conjures the characteristics of scalability, reliability, durability and fault tolerance, the overall characteristics of an end-to-end architecture must be appropriated as not all components will require such functionality. The characteristics of a general framework come from the need to make an architecture open and accessible to the widest audience possible, and to limit barriers to its use. A general architecture should also be modular and allow for components to be interchanged with alternative or more relevant technologies as they evolve and mature. Finally, a general architecture must have relevance to the area of study, but also be trending up within their uptake and use; this brings longevity to a general architecture. The characteristics of the proposed cloud robotic architecture to adhere to is summarised in Table 1.
Table 1.Characteristics for a generic cloud robotic architecture.
3.1 Robot Component
Utilising the robot middleware ROS (Robot Operating System) is ubiquitous when it comes to the research field of robotics. This platform is well established, actively supported, implemented upon basic robots right through to industrial implementations, and offers the greatest form of flexibility and features than any other robot middleware. Therefore, the robot component will not be exposed to an analysis.
3.2 Integration And Message System Component
The messaging system must satisfy a range of requirements to ensure it is suitable for a cloud robotics architecture and compatible with its interfacing components as seen in Fig. 1.
Figure.1 Messaging system framework between the ROS robot platform and Apache Spark big data platform
Table 2. Requirements for the messaging system and comparison between network implementations.
The IoT Cloud system  was first developed in 2012 as an open source cloud-compatible messaging system that utilises a combination of open source software that enables movement between sensor-centric devices and cloud-based system for data processing and storage. The system allows for both data and control messages to be sent between systems, and the handling of both block and streaming data in near real-time. The architecture includes Apache Zoo Keeper for device coordination, and a choice of supported message brokers (i.e. Active MQ, Rabbit MQ, Apache Kafka) to manage the movement of data into the cloud.
3.2.2 Message Broker
In terms of middleware communications, there are four main options which are compared in Table 3 below
Table 3. Comparison of middleware communication options and their functionalities.
From these options, Apache Flume and Apache Kafka were exposed to a deeper analysis as they are the most viable options for the messaging component of the architecture. This is detailed in Table 4 and the analysis below.
Table 4. Deeper comparison between Apache Flume and Apache Kafka.
Apache Flume is a more mature system with greater development, support, built-in integration to sources and sinks, and basic in-stream processing, however the system is geared towards one-way ingestion to a Highly Distributed File System (HDFS) datastore. This results in a lack of reliability, durability and spike handling capabilities compared to Apache Kafka, which creates a robust and versatile messaging system. The variable speed of Apache Kafka’s streams and the ease at which data can be consumed by multiple applications creates a flexible architecture in which sensor data of varying sizes and velocities can be saved or processed in different ways.
One limitation of Kafka as a general purpose messaging system is its support of only byte messages without any headers. Metadata about messages cannot be added as a header, and therefore when such metadata is required to be sent, a wrapper must beutilised such as Apache Thrift.
Figure.2 Updated message broker diagram demonstrating the use of IoTCloud and Apache Kafka in both client and cloud forms.
3.3 Big Data Processing Component
3.3.1 Processing Engine
For the last few years, debate in stream processing has been greatly contested between Apache Storm and Apache Spark Streaming. These two processing engines within the Apache ecosystem are also offered as services in the cloud, and contained within big data distributions, with both possessing their strengths and limitations. Storm and Spark among other competitors for the processing engine are compared in Table 4 below.
Table 4. Suitability of Apache products to serve as a cloud robotics engine
Storm possesses superior processing speed, with sub-second latency. Spark Streaming can only offer latency measured in seconds, however, the inherent latency with network communications reduces the importance of latency for cloud robotics.
Stateful operations are the ability for an engine to possess persistent memory and utilise this within stream processing for dynamic decision making. Spark Streaming possesses stateful operations by default, however Storm requires the use of third-party components or the use of Storm Trident in order to provide statefulness. Since statefulness is not built into the Storm architecture, such customisations may not be covered by Storm’s reliability and durability measures.Both Apache projects possess some of the most active Apache development communities, indicating both their popularity and relevance. Both projects are also offered in common big data distributions and are available as services by cloud service providers.
Lastly, the requirement for a consistent code-base for both batch and stream processing is becoming an important factor when selecting big data frameworks. The individual benefits that batch and stream processing provide have led to an acknowledgement that both forms of processing must exist. A single framework for query implementation and maintenance reduces the time and cost involved with development and support. Whilst this research has a focus on stream processing for initial cloud robotic processing, it is acknowledged that other forms of processing (i.e. batch, machine learning) will have their place. Storm requires development quite different from batch processing, whereas Spark provides a consistent development platform for multiple processing paradigms.
Due to Apache Spark Streaming’s stateful operation, single code-base and reduced importance placed on latency, this distributed stream processing engine will be chosen as the engine for use by the cloud robotics general architecture.
3.4 Cloud Infrastructure
The chosen big data platform must address the shortcomings of prior cloud robotic architectures utilising big data software, which include:
The use of a big data distribution over individual pieces of software has many benefits for the field of cloud robotics:
Big Data distributions also possess advantages over cloud providers, as distributions offer greater flexibility in where they can be deployed (i.e. onsite hardware, or using software such as Cloud Break to deploy on cloud providers if additional resources are required). Cloud providers also incur a cost, which would increase the barriers to a general cloud robotics architecture.
3.4.1 Big Data Distribution
Of the big data distributions investigated, only Cloudera and Hortonworks offer their distributions for free. Cloudera’s free distribution however is a cut-down version of the enterprise distribution, charged annually on a per node basis . The free Cloudera distribution (Cloudera Express) also does not offer stream processing support, and is only supported by Amazon’s AWS platform .
The Horton Distribution Platform (HDP)  is an Open Enterprise Hadoop platform, released entirely as a free and open distribution. As one of the largest contributors to the open source big data community, the company understands the core Apache big data ecosystem (i.e. Hadoop, Ambari, Storm, Spark etc), and combines these core projects into a stable platform with enterprise robustness and features. HDP is also the only distribution to currently support a non-Linux operating system in the form of the Windows platform. The distribution is available as a standalone sandbox distribution, which allows for a rapid implementation of a multi-node Hadoop cluster on a virtual machine, or as a standard distribution for custom deployments and configurations.
HDP contains both Apache Spark Streaming and Apache Kafka, and includes Apache Ambari for rapid deployment and management of the cluster. Partnering with Microsoft Azure and Rackspace to provision cloud based HDP clusters, their Cloud break software provides great flexibility when a HDP deployment is required to be hosted by a cloud provider. The complete HDP ecosystem supports core data storage and access, but also offers components for governance, integration, security and operations.
The landscape of big data has changed dramatically over the last four years, with the creation of an ecosystem of software, distributions, and cloud based providers offering big data as a service. The use of a big data distribution in a cloud robotic architecture is a novel approach, justified from the many benefits a stable, well supported and flexible platform brings to a big data deployment. HDP was selected as the most appropriate distribution for a general cloud robotics architecture due to its distribution being free and open, created by active open source contributors, and possesses flexible and unique deployment options.
3.4.2 Cloud Deployment And Infrastructure
Horton works released Cloud Break (assisted through the acquisition of Sequence IQ ) which can automatically provision and scale HDP clusters upon major cloud providers. Cloud break implements a policy-based auto-scaling system compatible with Azure, AWS, Google Cloud Platform, and providers using OpenStack, which allows HDP to elastically expand and contract on demand. Cloud break achieves this functionality through the creation of cloud provider templates which integrate the auto-scaling settings to the chosen provider, and also the creation of an Ambari blueprint which declares the cluster’s architecture, which defines how the cluster will be scaled.
The advantages of Cloud Break include:
4. Complete Architecture
The developed architecture is visualised in Fig. 3 and broken down into its functional components in Table 5 below.
Figure.3 Physical layout of the designed architecture and the interfaces between the chosen components.
Table 5. Complete architecture breakdown with choices of each component and a description of the software’s functionality.
The use of mature big data technologies in the emerging field of cloud robotics is an area of research in its infancy. The field of cloud computing offers enormous potential to robotics by leveraging the prodigious processing resources, information and services available in the cloud, making more complex sensing and decision making accessible to low cost robots. Big data is a more mature technology that has already developed the ability to leverage the power of the cloud, and the abilities that the field of cloud robotics can benefit from.
Whilst prior research has implemented cloud robotic and architectures which utilise big data components, the architectures of instances which yielded positive results were found to be:
This research has examined the major components of cloud robotics and conducted a thorough analysis of available technologies, and determined the most suitable for the purposes of cloud robotics. These components were then assembled to produce general cloud robotics architecture.
The contributions made by this research include:
By critically evaluating and justifying the composition and developing an easily replicable cloud robotic architecture, it is hoped that this research will modernise the existing approaches. Cloud robotics has taken with regards to big data technologies, and facilitate collaboration and verification to see this area of research mature.
6. Future Work
The development of generic cloud robotics architecture creates many avenues in which future work can be taken, in addition to emphasise the existing areas of cloud robotics which could be explored.
As the big data ecosystem continues to expand and grow with additional capabilities and processing power, the future of cloud robotics is going to be very exciting. The merging of artificial intelligence, big data, and cloud computing provides us a foundation with intelligence and computing power and resources in demand to tackle virtually any creative and unforeseen applications.
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