Denis Gracanin

Control architectures for autonomous underwater vehicles

Autonomous underwater vehicles (AUVs) share common control problems with other air, land, and water unmanned vehicles. In addition to requiring high-dimensional and computationally intensive sensory data for real-time mission execution, power and communication limitations in an underwater environment make it more difficult to develop a control architecture for an AUV. In this article, the four types of control architectures being used for AUVs (hierarchical, heterarchical, subsumption, and hybrid architecture) are reviewed. A summary of 25 existing AUVs and a review of 11 AUV control architecture systems present a flavor of the state of the art in AUV technology. A new sensor-based embedded AUV control system architecture is also described and its implementation is discussed.

A comparison of SOAP and REST implementations of a service based interaction independence middleware framework

This paper describes the conceptual design of an interaction independence middleware framework and describes the role that web services plays within it. We investigate two pervasive service-oriented architecture paradigms, SOAP and REST, in order to gauge their potential effectiveness in meeting underlying back-end data transmission requirements; provide implementations for the service-oriented architecture and data model; and, finally, critically evaluate both implementations with an emphasis on their performance with regard to both efficiency and scalability.

Interactive Visual Analysis of Families of Function Graphs

The analysis and exploration of multidimensional and multivariate data is still one of the most challenging areas in the field of visualization. In this paper, we describe an approach to visual analysis of an especially challenging set of problems that exhibit a complex internal data structure. We describe the interactive visual exploration and analysis of data that includes several (usually large) families of function graphs fi(x, t). We describe analysis procedures and practical aspects of the interactive visual analysis specific to this type of data (with emphasis on the function graph characteristic of the data). We adopted the well-proven approach of multiple, linked views with advanced interactive brushing to assess the data. Standard views such as histograms, scatterplots, and parallel coordinates are used to jointly visualize data. We support iterative visual analysis by providing means to create complex, composite brushes that span multiple views and that are constructed using different combination schemes. We demonstrate that engineering applications represent a challenging but very applicable area for visual analytics. As a case study, we describe the optimization of a fuel injection system in diesel engines of passenger cars

A service-centric model for wireless sensor networks

Most of the current research in wireless sensor networks (WSNs) is constraint driven and focuses on optimizing the use of limited resources (e.g., power) at each sensor. While such constraints are important, there is a energy for more general performance metrics to assess the effectiveness of WSNs. There is also a need for a unified formal model that would enable comparison of different types of WSNs and provide a framework for WSN operations. We propose a new service-centric model that focuses on services provided by a WSN and views a WSN as a service provider. A WSN is modeled at different levels of abstraction. For each level, a set of services and a set of metrics are defined. Services and their interfaces are defined in a formal way to facilitate automatic composition of services, and enable interoperability and multitasking of WSNs at the different levels. A two-way mapping between two neighboring levels is then defined as a decomposition (from higher to lower level) and composition (from lower to higher level). A composite mapping between metrics at different levels connects high-level, mission-oriented metrics and low-level, capability-oriented metrics. The service-centric model consists of mission, network, region, sensor, and capability layers. Each layer has associated semantics that use lower level components as syntactic units (except for the capability layer). Within each layer there are four planes or functionality sets; communication, management, application, and generational learning. The combination of layers and planes enables a service-based visualization paradigm that can provide better understanding of the WSN. The service-centric model provides a holistic approach to measuring and presenting WSNs effectiveness. In addition, it presents a general and flexible framework in which various more specific WSN models can be represented and evaluated.

Interactive Visual Steering - Rapid Visual Prototyping of a Common Rail Injection System

Interactive steering with visualization has been a common goal of the visualization research community for twenty years, but it is rarely ever realized in practice. In this paper we describe a successful realization of a tightly coupled steering loop, integrating new simulation technology and interactive visual analysis in a prototyping environment for automotive industry system design. Due to increasing pressure on car manufacturers to meet new emission regulations, to improve efficiency, and to reduce noise, both simulation and visualization are pushed to their limits. Automotive system components, such as the powertrain system or the injection system have an increasing number of parameters, and new design approaches are required. It is no longer possible to optimize such a system solely based on experience or forward optimization. By coupling interactive visualization with the simulation back-end (computational steering), it is now possible to quickly prototype a new system, starting from a non-optimized initial prototype and the corresponding simulation model. The prototyping continues through the refinement of the simulation model, of the simulation parameters and through trial-and-error attempts to an optimized solution. The ability to early see the first results from a multidimensional simulation space - thousands of simulations are run for a multidimensional variety of input parameters - and to quickly go back into the simulation and request more runs in particular parameter regions of interest significantly improves the prototyping process and provides a deeper understanding of the system behavior. The excellent results which we achieved for the common rail injection system strongly suggest that our approach has a great potential of being generalized to other, similar scenarios.

A framework for multiuser distributed virtual environments

A framework for multi-user distributed virtual environments (DVEs) has been proposed. The proposed framework, incorporating two models (the functional model and the interconnection model), attempts to represent the common functionality, communication issues and requirements found in multi-user DVEs. The functional model concentrates on the DVEs functionality, while the interconnection model concentrates on how the components are interconnected to realize the required functionality. The models have been specified using the Unified Modeling Language (UML). An experimental case study demonstrates the applicability and generality of the proposed approach.

iPhone/iPod Touch as Input Devices for Navigation in Immersive Virtual Environments

iPhone and iPod Touch are multi-touch handheld devices that provide new possibilities for interaction techniques. We describe iPhone/iPod Touch implementation of a navigation interaction technique originally developed for a larger multi-touch device (i.e. Lemur). The interaction technique implemented on an iPhone/iPod Touch was used for navigation tasks in a CAVE virtual environment. We performed a pilot study to measure the control accuracy and to observe how human subjects respond to the interaction technique on the iPhone and iPod Touch devices. We used the preliminary results to improve the design of the interaction technique.

Interactive Visual Analysis of Multiple Simulation Runs Using the Simulation Model View: Understanding and Tuning of an Electronic Unit Injector

Multiple simulation runs using the same simulation model with different values of control parameters generate a large data set that captures the behavior of the modeled phenomenon. However, there is a conceptual and visual gap between the simulation model behavior and the data set that makes data analysis more difficult. We propose a simulation model view that helps to bridge that gap by visually combining the simulation model description and the generated data. The simulation model view provides a visual outline of the simulation process and the corresponding simulation model. The view is integrated in a Coordinated Multiple Views; (CMV) system. As the simulation model view provides a limited display space, we use three levels of details. We explored the use of the simulation model view, in close collaboration with a domain expert, to understand and tune an electronic unit injector (EUI). We also developed analysis procedures based on the view. The EUI is mostly used in heavy duty Diesel engines. We were mainly interested in understanding the model and how to tune it for three different operation modes: low emission, low consumption, and high power. Very positive feedback from the domain expert shows that the use of the simulation model view and the corresponding ;analysis procedures within a CMV system represents an effective technique for interactive visual analysis of multiple simulation runs.

Interactive visual analysis and exploration of injection systems simulations

Simulations often generate large amounts of data that require use of SciVis techniques for effective exploration of simulation results. In some cases, like 1D theory of fluid dynamics, conventional SciVis techniques are not very useful. One such example is a simulation of injection systems that is becoming more and more important due to an increasingly restrictive emission regulations. There are many parameters and correlations among them that influence the simulation results. We describe how basic information visualization techniques can help in visualizing, understanding and analyzing this kind of data. The Com Vis tool is developed and used to analyze and explore the data. Com Vis supports multiple linked views and common information visualization displays such as 2D and 3D scatter-plot, histogram, parallel coordinates, pie-chart, etc. A diesel common rail injector with 2/2 way valve is used for a case study. Data sets were generated using a commercially available AVL HYDSIM simulation tool for dynamic analysis of hydraulic and hydro-mechanical systems, with the main application area in the simulation of fuel injection systems.

Finger Walking in Place (FWIP): A Traveling Technique in Virtual Environments

In this paper we present a Finger Walking in Place (FWIP) interaction technique that allows a user to travel in a virtual world as her/his bare fingers slide on a multi-touch sensitive surface. Traveling is basically realized by translating and rotating the users viewpoint in the virtual world. The user can translate and rotate a viewpoint by moving her/his fingers in place. Currently, our FWIP technique can be used to navigate in a plane but it can be extended to navigate in the third axis, so that the user can move to any direction in a 3D virtual world. Since our FWIP technique only uses bare fingers and a multi-touch device, finger motions are not precisely detected, especially compared with the use of data gloves or similar sensing devices. However, our experiments show that FWIP can be used as a novel traveling technique even without accurate motion detection. Our experiment tasks include finding and reaching the target(s) with FWIP, and the participants successfully completed the tasks. The experiments illustrate our efforts to make the FWIP technique robust as a scaled-down walking-in-place locomotion technique, so that it can be used as a reliable traveling technique.