A Software Architecture for Sharing Distributed Virtual Worlds

This study is concerned with semantic modelling of virtual environments (VEs). A semantic model of a VE provides an abstract and high level representation of main aspects of the environment: ontological structures, behaviours and interactions of entities, etc. Furthermore, such a semantic model can be explored by artificial agents to exhibit human-like behaviours or to assist users in the VE. Previous research focused on formalising a knowledge layer that is a conceptual representation of scene content or application's entities. However, there still lacks of a semantic representation of spatial knowledge. This paper proposes to integrate a semantic model of directional knowledge into VEs. Such a directional model allows to specify relationships such as left, right, above or north, south that are critical in many applications of VEs (e.g., VEs for training, navigation aid systems). We focus particularly on modelling, computing, and visualising directional relationships. First, we propose a theoretical model of direction in VEs that enables the specification of direction both from a first- and third-person perspective. Second, we propose a generic architecture for modelling direction in VEs using a meta-modelling approach. Directional relationships are described in a qualitative manner and at a conceptual level, and thus are abstract from metrical details of VEs. Finally, we show how our semantic model of direction can be used in a cultural heritage application to specify behaviours of artificial agents and to visualise directional constraints.

The goal of the proposed device and software architecture is to apply the functionality of mixed reality (MR) in order to make a virtual environment that is more accessible to the visually-impaired. We propose a glove-based system for MR that will use finger and hand movement tracking along with tactile feedback so that the visually-impaired can interact with and obtain a more detailed sense of virtual objects and potentially even virtual environments. The software architecture makes current MR frameworks more accessible by augmenting the existing software and extensive 3D model libraries with both the interfacing of the glove-based system and the audibly navigable user interface (UI) of a virtual environment we have developed. We implemented a circuit with finger flexion/extension tracking for all 5 fingers of a single hand and variable vibration intensities for the vibromotors on all 5 fingertips of a single hand. The virtual environment can be hosted on a Windows 10 application. The virtual hand and its fingers can be moved with the system's input and the virtual fingertips touching the virtual objects trigger vibration motors (vibromotors) to vibrate while the virtual objects are being touched. A rudimentary implementation of picking up and moving virtual objects inside the virtual environment is also implemented. In addition to the vibromotor responses, text to speech (TTS) is also implemented in the application for when virtual fingertips touch virtual objects and other relevant events in the virtual environment.

Although various publications confirm the need for a generic DRM software architecture, we observe that current efforts to define a DRM architecture do not always provide sufficient support to enable the creation and management of DRM systems and content distribution applications. This is a considerable problem that implies a crucial challenge for the evolution of DRM, given the impact of a software architecture on the functional and non-functional qualities of the implemen- tation. This paper (1) presents a generic DRM architecture, (2) evaluates it in the context of interoperability, extendability, and modifiability, and (3) compares it to related work in the Digital Media Project (DMP). To the best of our knowledge, the proposed architecture is more detailed than related work published so far.

Over the past two decades, scholars developed various unmanned sailboat platforms, but most of them have specialized designs and controllers. Whereas these robotic sailboats have good performance with open-source designs, it is actually hard for interested researchers or fans to follow and make their own sailboats with these open-source designs. Thus, in this paper, a generic and flexible unmanned sailboat platform with easy access to the hardware and software architectures is designed and tested. The commonly used 1-m class RC racing sailboat was employed to install Pixhawk V2.4.8, Arduino Mega 2,560, GPS module M8N, custom-designed wind direction sensor, and wireless 433 Mhz telegram. The widely used open-source hardware modules were selected to keep reliable and low-cost hardware setup to emphasize the generality and feasibility of the unmanned sailboat platform. In software architecture, the Pixhawk V2.4.8 provided reliable states’ feedback. The Arduino Mega 2,560 received estimated states from Pixhawk V2.4.8 and the wind vane sensor, and then controlled servo actuators of rudder and sail using simplified algorithms. Due to the complexity of introducing robot operating system and its packages, we designed a generic but real-time software architecture just using Arduino Mega 2,560. A suitable line-of-sight guidance strategy and PID-based controllers were used to let the autonomous sailboat sail at user-defined waypoints. Field tests validated the sailing performance in facing WRSC challenges. Results of fleet race, station keeping, and area scanning proved that our design and algorithms could control the 1-m class RC sailboat with acceptable accuracy. The proposed design and algorithms contributed to developing educational, low-cost, micro class autonomous sailboats with accessible, generic, and flexible hardware and software. Besides, our sailboat platform also facilitates readers to develop similar sailboats with more focus on their missions.

A generic flexible and scalable framework for hierarchical parallelization of population-based metaheuristics

In this paper, a general architecture is proposed for developing embodied conversational agents with fuzzy ontology knowledge base. The proposed architecture enables agents to interact with the user via multimodal channels in a virtual reality environment for the purpose of language learning. The agents play the role of emotional, rational, and friendly partners who provide a specific domain of knowledge based on user's queries in natural language. These queries are performed by an optimized fuzzy search engine. Two scenarios including two virtual airports and a virtual electronic gadget shop are implemented in this architecture to improve users' oral skills. The results show the users' average oral skills improved 11%. Moreover, 80% of the users ranked agents' logical sequence of actions and the total speed of responses as very good, and 90% of them evaluated agents' appropriateness of responses as very good based on Likert scale.

The U.S. Army Research Institute is investigating the use of virtual environment (VE) technologies to train personnel in distributed simulations. As part of this endeavor, we compared the communication activities of 2 team types as they completed a series of missions in a common VE. Local teams were comprised of 2 members situated in the same physical location, whereas distributed team members were separated geographically and had no opportunity for face-to-face communication. Following the first 7 (of 8 total) missions, communications were recorded as each team completed an after action review of their performance. Analyses of the amount and type of communication acts revealed no significant differences between local and distributed teams, even though significant performance differences were found for these team types during the VE missions. Results suggest that nonverbal communication likely mediated the relationship between networking condition and team performance.

Virtual and physical rapid prototyping of mobile robots is often necessary not only in the development of research platforms, but also for validating commercial and customized mobile robot applications. The design of a robot involves specialized knowledge from mechanical, electrical and software engineering. Despite summarizing the wide variety of tools and knowledge is a challenging task, this chapter presents the main guidelines and recommendations for the design and rapid prototyping of mobile robots. The chapter reviews basic design rules, the fundamental robot components, the general hardware and software architecture. The discussion includes aspects that are key to the selection of those components that ensure the robot prototype meets the motion specifications, such as the selection of computing platforms, the main types of mechanical transmissions, efficiency issues, the role of bearings and other aspects concerning stability, overturning margins, controllability and the motion dynamics. Finally, all the concepts and guidelines are employed in the design of a skid-steer mobile robot, which is presented as an example of rapid mobile robot prototyping. A summary of the main conclusions and suggestions for further reading is presented in the last section.

Future onboard computing applications require significantly greater computing performance than is currently provided by standard space qualified onboard computers. Examples of such applications include onboard data analysis and (rendezvous) navigation tasks. Therefore, the German Aerospace Center is currently developing Scalable On-board Computing for Space Avionics (ScOSA). The aim of the ScOSA onboard computing platform is to deliver high performance, reliability, scalability and cost-efficiency.
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\nTo reach these properties, a distributed computing platform approach is used, by which reliable radiation hardened computing nodes (LEON3's) are combined with several high performance computing nodes (Xilinx Zynq), connected over a high-bandwidth SpaceWire network. The execution platform consists of a distributed task-based framework.
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\nIn this paper, the architecture, features and capabilities of the ScOSA onboard computing platform are presented from an application developer's view. A brief summary of the design goals and the general hardware and software architecture of the ScOSA system will be introduced. This is followed by a description of the programming model and the application interface, with a focus on how the distributed nature of the ScOSA system is handled. It will also be shown how an existing application can be integrated in the ScOSA system.
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\nThe main part of this paper will focus on the computing performance attainable from the ScOSA platform. There will be a comparison of the computing performance of an example application executed on the ScOSA system versus a standard PC. It will also be demonstrated how the performance of an application can be improved by adapting it to the distributed computing architecture of the ScOSA platform. Furthermore, a short overview of the failure detection and recovery features of the ScOSA platform are described and how they can be integrated into an application.

This paper presents the intelligent virtual animals that inhabit Omosa, a virtual learning environment to help secondary school students learn how to conduct scientific inquiry and gain concepts from biology. Omosa supports multiple agents, including animals, plants, and human hunters, which live in groups of varying sizes and in a predator-prey relationship with other agent types (species). In this paper we present our generic agent architecture and the algorithms that drive all animals. We concentrate on two of our animals to present how different parameter values affect their movements and inter/intra-group interactions. Two evaluations studies are included: one to demonstrate the effect of different components of our architecture; another to provide domain expert validation of the animal behavior.

The National Research Council report entitled ”Modeling and Simulation — Linking Entertainment and Defense” described a basic and applied research agenda applicable to both the virtual reality and entertainment research communities. The Naval Postgraduate School has developed an educational and research program in support of the report’s agenda with foci on technologies for immersion (low-cost 3D image generation, spatial tracking, game platform utilization, multimodal sensory presentation), networked simulation (high bandwidth networks, dynamically extensible network software architectures, area of interest management, techniques for latency reduction, standards for interoperability), and computer-generated autonomy (agent-based simulation, adaptability, learning, human behavior representations). In the presentation, we examine the future of networked entertainment and its requirements also useful for modeling, virtual environments and simulation. We then look at some particular efforts being carried out by the Naval Postgraduate School’s Modeling, Virtual Environments and Simulation (MOVES) Academic Group.

In order to use realistic image synthesis successfully in research and development as well as in commercial products, two important prerequisites have to be fulfilled. First of all, good, accurate, robust, and fast algorithms are required. Impressive progress has been made in this respect during the last years, which has also been documented in this workshop. The second step is the creation of a suitable and general software architecture, that offers an environment into which these rendering algorithms can be integrated.

Stereoscopic depth cues improve depth perception and increase immersion within virtual environments (VEs). However, improper display of these cues can distort perceived distances and directions. Consider a multi-user VE, where all users view identical stereoscopic images regardless of physical location. In this scenario, cues are typically customized for one "leader" equipped with a head-tracking device. This user stands at the center of projection (CoP) and all other users ("followers") view the scene from other locations and receive improper depth cues. This paper examines perceived depth distortion when viewing stereoscopic VEs from follower perspectives and the impact of these distortions on collaborative spatial judgments. Pairs of participants made collaborative depth judgments of virtual shapes viewed from the CoP or after displacement forward or backward. Forward and backward displacement caused perceived depth compression and expansion, respectively, with greater compression than expansion. Furthermore, distortion was less than predicted by a ray-intersection model of stereo geometry. Collaboration times were significantly longer when participants stood at different locations compared to the same location, and increased with greater perceived depth discrepancy between the two viewing locations. These findings advance our understanding of spatial distortions in multi-user VEs, and suggest a strategy for reducing distortion.

In the past decade, software architecture research has mainly focused on the concept formulation and the development of various architecture description languages. This field has now matured enough and thus requires more emphasis on techniques for developing and analyzing software architecture specifications. SAM is a general software architecture model for developing and analyzing software architectures. In this paper, we show how to integrate high-level Petri nets and first-order temporal logic as the foundation of SAM to establish a unified framework for specifying and analyzing all aspects of a software architecture. We provide a set of heuristics, which are supported by well-defined existing methods and techniques developed by other researchers as well as our own, for software architecture development and analysis. We demonstrate the application of this framework and the heuristics with an example.

Online telesupervision (OTS) is synchronous (real-time) audio and video interactions between a supervisor and a clinician who are not in the same physical location. The COVID-19 pandemic created an abrupt pivot to OTS, requiring systemic supervisors and clinicians to adopt and utilize technologies which were unfamiliar to many. To facilitate the effective adoption and implementation of OTS we draw attention to three distinct competencies critical to the effective use of OTS: technological, contextual, and relational. These competencies are in no way exhaustive but lay the ground work for systemic supervisors to engage and connect with supervisees using video conferencing technology. In addition to the competencies, specific techniques and strategies are suggested to assist supervisors hone their skills in OTS and subsequently improve the quality and effectiveness of supervision in a virtual environment.