TY - JOUR T1 - Task Transition Scheduling for Data-Adaptable Systems JF - ACM Transactions on Embedded Computing Systems (TECS) Y1 - 2017 A1 - Nathan Sandoval A1 - Casey Mackin A1 - Sean Whitsitt A1 - Gopinath, Vijay Shankar A1 - Sachidanand Mahadevan A1 - Milakovich, Andrew A1 - Merry, Kyle A1 - Jonathan Sprinkle A1 - Roman Lysecky KW - Data adaptability KW - hardware/software codesign KW - model-based design KW - runtime transition scheduling AB -
Data-adaptable embedded systems operate on a variety of data streams, which requires a large degree of configurability and adaptability to support runtime changes in data stream inputs. Data-adaptable reconfigurable embedded systems, when decomposed into a series of tasks, enable a flexible runtime implementation in which a system can transition the execution of certain tasks between hardware and software while simultaneously continuing to process data during the transition. Efficient runtime scheduling of task transitions is needed to optimize system throughput and latency of the reconfiguration and transition periods. In this article, we provide an overview of a runtime framework enabling the efficient transition of tasks between software and hardware in response to changes in system inputs. We further present and analyze several runtime transition scheduling algorithms and highlight the latency and throughput tradeoffs for two data-adaptable systems. To evaluate the task transition selection algorithms, a case study was performed on an adaptable JPEG2000 implementation as well as three other synchronous dataflow systems characterized by transition latency and communication load.
VL - 16 UR - http://doi.acm.org/10.1145/3047498 ER - TY - CONF T1 - Automatic Verification of Dynamic Constraints in LTI Control Systems Through Model Transformations T2 - NSF Young Professionals Workshop on Exploring New Frontiers in Cyber-Physical Systems Y1 - 2014 A1 - Sean Whitsitt KW - Controls KW - Dynamic Constraints KW - Model Transformations JF - NSF Young Professionals Workshop on Exploring New Frontiers in Cyber-Physical Systems PB - NSF CY - Washington, DC ER - TY - CONF T1 - Generating Model Transformations for Mending Dynamic Constraint Violations in Cyber Physical Systems T2 - The 14th Workshop on Domain-Specific Modeling Y1 - 2014 A1 - Sean Whitsitt A1 - Jonathan Sprinkle A1 - Roman Lysecky AB -Cyber physical systems by definition involve design constraints addressing the computation and communication necessary to control physical systems. These systems have been modeled using domain specific modeling languages, but some limitations exist in the continued application of such a modeling approach to more complex, or safety-critical, systems. Specifically, it is well known how to formulate constraints in a domain-specific modeling language in order to prevent users from building invalid structures, but existing constraint-based techniques do not take into consideration design requirements that may require analysis in the physical domain (i.e. dynamic constraints). Those analysis results, when interpreted by a domain expert, can inform changes to the model: unfortunately, this process does not scale. This paper presents an approach to integrating dynamic constraints that cannot be enforced using structural model constraints. The technique uses expert blocks to analyze systems and generates model transformations specific to the system using the results of those analyses to fix constraint violations. The paper describes a Dynamic Constraint Feedback (DCF) methodology for integrating this technique into existing systems from a generic perspective. Specific examples in this paper are derived from the domain of data adaptable reconfigurable embedded systems (DARES).
JF - The 14th Workshop on Domain-Specific Modeling UR - http://dx.doi.org/10.1145/2688447.2688454 ER - TY - CONF T1 - A Hybrid Controller for Autonomous Vehicle Lane Changing with Epsilon Dragging T2 - American Control Conference Y1 - 2014 A1 - Sean Whitsitt A1 - Jonathan Sprinkle AB -Trajectory control for a ground vehicle typically utilizes the error from the desired path or trajectory (i.e., crosstrack error) to produce velocity and steering commands. If an obstacle is in the path, previous techniques have synthesized a new trajectory that avoids the obstacles, and the vehicle directly follows this new path. This approach has drawbacks at high velocity, because the synthesized trajectory must satisfy the stability criteria of the vehicle. This paper introduces a technique which we call epsilon dragging The approach modifies the existing trajectory by some value ε in order to avoid an obstacle at high speeds, while preserving the original trajectory as the desired path. Epsilon dragging is performed by inducing an additional error to the crosstrack error of the vehicle; this induced error can be bounded in order to stay within the velocity/turnrate profile that governs safe behavior at high speeds. The paper provides a method to construct epsilon such that a vehicle can avoid an obstacle at high speeds without the need to verify the trajectory’s curvature before it is synthesized. The technique is demonstrated in completing a lane-change maneuver at different velocities, and verifying that the velocity/turnrate profiles are not exceeded.
JF - American Control Conference PB - IEEE CY - Portland, Oregon UR - http://dx.doi.org/10.1109/ACC.2014.6859450 ER - TY - THES T1 - A Methodology for Mending Dynamic Constraint Violations in Cyber Physical Systems By Generating Model Transformations Y1 - 2014 A1 - Sean Whitsitt PB - University of Arizona CY - Tucson, AZ VL - PhD ER - TY - CONF T1 - Efficient Reconfiguration Methods to Enable Rapid Deployment of Runtime Reconfigurable Systems T2 - Asilomar Conference on Signals, Systems and Computers Y1 - 2013 A1 - Roman Lysecky A1 - Nathan Sandoval A1 - Sean Whitsitt A1 - Casey Mackin A1 - Jonathan Sprinkle JF - Asilomar Conference on Signals, Systems and Computers PB - IEEE CY - Pacific Grove, CA UR - http://dx.doi.org/10.1109/ACSSC.2013.6810401 ER - TY - CONF T1 - Generating a ROS/JAUS Bridge for an Autonomous Ground Vehicle T2 - Proceedings of the 2013 ACM workshop on Domain-specific modeling (DSM ’13) Y1 - 2013 A1 - Patrick Morley A1 - Alex Warren A1 - Ethan Rabb A1 - Matthew Bunting A1 - Sean Whitsitt A1 - Jonathan Sprinkle KW - autonomous vehicles KW - Code Generation AB -Robotic systems have truly benefitted from standardized middleware that can componentize the development of new capabilities for a robot. The popularity of these robotic middleware systems has resulted in sizable libraries of components that are now available to roboticists. However, many robotic systems (such as autonomous vehicles) must adhere to externally defined standards that are not blessed with such a large repository of components. Due to the real-time and safety concerns that accompany the domain of unmanned systems, it is not trivial to interface these middleware systems, and previous attempts to do so have succeeded at the cost of ad hoc design and implementation. This paper describes a domain-specific approach to the synthesis of a bridge between the popular Robotic Operating System (ROS) and the Joint Architecture for Unmanned Systems (JAUS). The domain-specific nature of the approach permits the bridge to be limited in scope by the application’s specific messages (and their attribute mappings between JAUS/ROS), resulting in smaller code size and overhead than would be incurred by a generic solution. Our approach is validated by tests performed on an unmanned vehicle with and without the JAUS/ROS bridge.
JF - Proceedings of the 2013 ACM workshop on Domain-specific modeling (DSM ’13) PB - ACM CY - Indianapolis, IN UR - http://dx.doi.org/10.1145/2541928.2541931 ER - TY - CONF T1 - Model Based Development with the Skeleton Design Method T2 - 20th IEEE International Conference and Workshops on the Engineering of Computer Based Systems Y1 - 2013 A1 - Sean Whitsitt A1 - Jonathan Sprinkle A1 - Roman Lysecky JF - 20th IEEE International Conference and Workshops on the Engineering of Computer Based Systems UR - http://dx.doi.org/10.1109/ECBS.2013.16 ER - TY - JOUR T1 - Modeling Autonomous Systems JF - AIAA Journal of Aerospace Information Systems Y1 - 2013 A1 - Sean Whitsitt A1 - Jonathan Sprinkle VL - 10 UR - http://dx.doi.org/10.2514/1.I010039 ER - TY - CONF T1 - Runtime Hardware/Software Task Transition Scheduling for Runtime-Adaptable Embedded Systems T2 - International Conference on Field-Programmable Technology (ICFPT) Y1 - 2013 A1 - Nathan Sandoval A1 - Casey Mackin A1 - Sean Whitsitt A1 - Roman Lysecky A1 - Jonathan Sprinkle JF - International Conference on Field-Programmable Technology (ICFPT) UR - http://dx.doi.org/10.1109/FPT.2013.6718382 ER - TY - CONF T1 - System Throughput Optimization and Runtime Communication Middleware Supporting Dynamic Software-Hardware Task Migration in Data Adaptable Embedded Systems T2 - Engineering of Computer Based Systems (ECBS), 2013 20th IEEE International Conference and Workshops on the Y1 - 2013 A1 - Nathan Sandoval A1 - Casey Mackin A1 - Sean Whitsitt A1 - Roman Lysecky A1 - Jonathan Sprinkle KW - combinatorial explosion KW - Data adaptability KW - data adaptable design methodology KW - data adaptable embedded systems KW - data configurations KW - data handling KW - Data models KW - data profile correlation KW - design time optimization KW - dynamic software-hardware task migration KW - embedded systems KW - Field programmable gate arrays KW - FIFO queues KW - Firing KW - Hardware KW - hardware accelerators KW - hardware-software codesign KW - hardware-software communication wrapper KW - hardware/software codesign KW - hardware/software communication middleware KW - heuristic programming KW - heuristic search methodology KW - middleware KW - model-based design KW - Pareto optimal configurations KW - Pareto optimisation KW - Runtime KW - runtime communication middleware KW - search problems KW - simulation-based methodology KW - system throughput optimization JF - Engineering of Computer Based Systems (ECBS), 2013 20th IEEE International Conference and Workshops on the ER - TY - CONF T1 - On the Extraction and Analysis of a Social Network with Partial Organizational Observation T2 - Proceedings of the 19th IEEE International Conference and Workshops on Engineering of Computer-Based Systems Y1 - 2012 A1 - Sean Whitsitt A1 - Abishek Gopalan A1 - Sangman Cho A1 - Jonathan Sprinkle A1 - Srinivasan Ramasubramanian A1 - Liana Suantak A1 - Jerzy Rozenblit AB -The behavior of an organization may be inferred based on the behavior of its members, their contacts, and their connectivity. One approach to organizational analysis is the construction and interpretation of a social network graph, where entities of an organization (persons, vehicles, locations, events, etc.) are nodes, and edges represent varying kinds of connectivity between entities. This paper describes a transformation based approach to the extraction of a social network graph, where the original data comprising (partial) observation of the organization are embedded on a graph with a different ontology, and with many entities and edges that are unrelated to the organization of interest. Social network extraction allows the inference of implied relationships, and the selection of relationships relevant for intended analysis techniques. The analysis of the resulting social network graph is based on organizational and individual analysis, in order to permit an advanced user to draw conclusions regarding the behavior of the organization, based on established social network graph metrics. The results of the paper include a discussion of the complexity of analysis, and how the observation data graph is pruned in order to scale the application of analysis algorithms.
JF - Proceedings of the 19th IEEE International Conference and Workshops on Engineering of Computer-Based Systems UR - http://dx.doi.org/10.1109/ECBS.2012.33 ER - TY - CONF T1 - Modeling and Code Generation with Autonomous Vehicles T2 - ACM/IEEE 15th International Conference on Model Driven Engineering Languages and Systems Doctoral Symposium Y1 - 2012 A1 - Sean Whitsitt JF - ACM/IEEE 15th International Conference on Model Driven Engineering Languages and Systems Doctoral Symposium CY - Innsbruck Austria ER - TY - CONF T1 - An Overseer Control Methodology for Data Adaptable Embedded Systems T2 - International Workshop on Multi-Paradigm Modeling (MPM) Y1 - 2012 A1 - Sean Whitsitt A1 - Jonathan Sprinkle A1 - Roman Lysecky JF - International Workshop on Multi-Paradigm Modeling (MPM) UR - http://dx.doi.org/10.1145/2508443.2508448 ER - TY - CONF T1 - A Passenger Comfort Controller for an Autonomous Ground Vehicle T2 - 51st IEEE Conference on Decision and Control Y1 - 2012 A1 - Sean Whitsitt A1 - Jonathan Sprinkle JF - 51st IEEE Conference on Decision and Control UR - http://dx.doi.org/10.1109/CDC.2012.6426049 ER - TY - CONF T1 - Constrained data acquisition for mobile citizen science applications T2 - Proceedings of the compilation of the co-located workshops on DSM’11, TMC’11, AGERE!’11, AOOPES’11, NEAT’11, & VMIL’11 Y1 - 2011 A1 - Sean Whitsitt A1 - Armando Barreto A1 - Maribel Hudson A1 - Hussain Al-Helal A1 - Diyang Chu A1 - Kamel Didan A1 - Jonathan Sprinkle KW - citizen scientist KW - domain-specific modeling KW - iphone KW - mobile phone programming AB -The popularity and ubiquity of personal mobile computing devices–-coupled with their powerful sensing capabilities–-allow their application in the structured collection of data for societal benefit and science applications. Citizen scientists are willing users and active contributors to scientific research and applications, but if they gather data in an unconstrained or ad hoc manner, their efforts may be of little scientific value. In this paper, we present a user interface for a mobile device which is properly constrained to permit the gathering of valid scientific data. This helps to achieve the goal that any individual with a basic familiarity of the device (but not of the science) should be able to obtain useful data with little learning required. As a use case for this concept, we present a mobile application that allows users to collect location-stamped images to supplement satellite data for climate change research.
JF - Proceedings of the compilation of the co-located workshops on DSM’11, TMC’11, AGERE!’11, AOOPES’11, NEAT’11, & VMIL’11 T3 - SPLASH ’11 Workshops PB - ACM CY - New York, NY, USA SN - 978-1-4503-1183-0 UR - http://dx.doi.org/10.1145/2095050.2095095 ER - TY - CONF T1 - Message Modeling for the Joint Architecture for Unmanned Systems (JAUS) T2 - Proceedings of the 8th IEEE Workshop on Model-Based Development for Computer-Based Systems Y1 - 2011 A1 - Sean Whitsitt A1 - Jonathan Sprinkle AB - The Joint Architecture for Unmanned Systems (JAUS) is a standard for sensing, control, and computational communication of components for unmanned systems. This paper presents a modeling environment capable of producing a domain-specific prototype of the software necessary for inter-computer communications. A metamodel is used to provide the domain-specific modeling language to model both the messages used in JAUS, and the shell interfaces for components that transmit and receive those messages. The produced artifacts are C and C++ code that can be used in unmanned systems and simulations of such systems, including tests that validate the structure and behavior of the generated code. The generated code is compatible with standard JAUS implementations, and is validated using the OpenJAUS open source API and framework. Future work describes the second spiral of features and behaviors (currently in the design phase). The case study and test environment for the software generated by this project is an autonomous ground vehicle, modeled on a Ford Escape Hybrid that is used in laboratory experiments. JF - Proceedings of the 8th IEEE Workshop on Model-Based Development for Computer-Based Systems UR - http://dx.doi.org/10.1109/ECBS.2011.17 ER - TY - THES T1 - Modeling the Messaging and Component Interfaces of Autonomous Systems Y1 - 2011 A1 - Sean Whitsitt PB - University of Arizona UR - http://bracton.ece.arizona.edu/svn/jmsgroup/trunk/public/whitsitt-thesis.pdf ER - TY - CONF T1 - Citizen Science in Support of Vegetation Index and Phenology Research T2 - Phenology Research and Observations of Southwest Ecosystems Symposium (PROSE) Y1 - 2010 A1 - Sean Whitsitt A1 - Armando Barreto A1 - Sundaresh Ram A1 - Hussain Al-Helal A1 - Maribel Hudson A1 - Diyang Chu A1 - Jonathan Sprinkle A1 - Kamel Didan AB -Vegetation indices (VIs) are simple transformations of images into proxy measures of greenness and vegetation health and change over time. They are also used to derive information about the land surface phenology status, providing extensive spatial coverage and direct support for global ecosystem models. These measurements however contain large uncertainties and errors. A new suite of mobile devices, equipped with geo-location, image capture, and transmission capabilities could aid with vegetation phenology observations and documentation. The iPhone, with its wide distribution and array of sensors, can contribute significantly to the field of citizen science. In this project we are developing an end-to-end system for the collection, processing, and visualization of land surface vegetation phenology. The system consists of a client-server application and a Google Earth based visualization model. The client side (an iPhone app) intuitively guides the observer to capture up to three images per location: a close-up image of leaves, flowers, or fruits, an individual plant image, and a panoramic landscape image. The iPhone automatically embeds location, orientation, date/time, and other metadata with the images and allows the observer to add text comments. The images are then transmitted to the server, where they are validated, post-processed, archived, and made available to the interactive visualization system. The images are separated into primary colors and processed into a greenness index comparable to the classical VI. These measurements are then plotted against satellite based VI time series to aid in their validation and the characterization of the location phenology. With this effort we hope to recruit global observers into contributing to the field of land surface vegetation change detection and characterization.
JF - Phenology Research and Observations of Southwest Ecosystems Symposium (PROSE) ER -