Recursive dynamics for flexible multibody systems using spatial operators

Due to their structural flexibility, spacecraft and space manipulators are multibody systems with complex dynamics and possess a large number of degrees of freedom. Here the spatial operator algebra methodology is used to develop a new dynamics formulation and spatially recursive algorithms for such flexible multibody systems. A key feature of the formulation is that the operator description of the flexible system dynamics is identical in form to the corresponding operator description of the dynamics of rigid multibody systems. A significant advantage of this unifying approach is that it allows ideas and techniques for rigid multibody systems to be easily applied to flexible multibody systems. The algorithms use standard finite-element and assumed modes models for the individual body deformation. A Newton-Euler Operator Factorization of the mass matrix of the multibody system is first developed. It forms the basis for recursive algorithms such as for the inverse dynamics, the computation of the mass matrix, and the composite body forward dynamics for the system. Subsequently, an alternative Innovations Operator Factorization of the mass matrix, each of whose factors is invertible, is developed. It leads to an operator expression for the inverse of the mass matrix, and forms the basis for the recursive articulated body forward dynamics algorithm for the flexible multibody system. For simplicity, most of the development here focuses on serial chain multibody systems. However, extensions of the algorithms to general topology flexible multibody systems are described. While the computational cost of the algorithms depends on factors such as the topology and the amount of flexibility in the multibody system, in general, it appears that in contrast to the rigid multibody case, the articulated body forward dynamics algorithm is the more efficient algorithm for flexible multibody systems containing even a small number of flexible bodies. The variety of algorithms described here permits a user to choose the algorithm which is optimal for the multibody system at hand. The availability of a number of algorithms is even more important for real-time applications, where implementation on parallel processors or custom computing hardware is often necessary to maximize speed

Trends on interactive platforms for social media through Web2.0

With the rapid development of the Internet, social networking on Web2.0 becomes a novel social media for mass communication. It relies on new online technologies and practices to enable ordinary people to share opinions, insights, expertise, experiences, and interests with each other and further reduce the barriers to collaboration, skill-building and discovery. Web2.0 as the next generation of networking services emphasizes social interaction and share of user-generated content in a collaborative environment. It has evolved and transferred the Internet into a platform by supporting rich digital media technology for the development of innovative business, educational, and cultural applications. In conjunction with Web 3D technology, social networking has already begun to foster an intuitive and immersive system that allows effective visual communication and delivers real time natural interactive experience for enhancing user motivation and engagement compared with the traditional static and text-oriented online information systems and content management systems

Real-time comparisons of ionospheric data with outputs from the UAF eulerian parallel polar ionosphere model

Thesis (M.S.) University of Alaska Fairbanks, 2007The UAF theoretical polar ionospheric model (UAF EPPIM) solves 3D equations of mass, momentum, and energy balance for multiple ion species to determine ion and electron parameters in the polar ionosphere region using a parallel numerical code on an Eulerian grid. Real time operation of the model is very important because users are interested in current space weather conditions. Real-time validation of this model with available experimental data is an important task for the following reasons. (1) Real-time validation can provide much information about the model quality and define the directions of improvement. (2) Real-time comparisons help to determine trusted intervals for the model parameters for future data assimilation tasks. In this work, we have developed an operational real-time comparisons capability which assimilates HAARP (High frequency Active Auroral Research Program) experimental data for the model validation purposes. Software has been developed to emulate Total Electron Content (TEC). Results are then compared with real-time data from HAARP. Further, we have developed a Computerized Ionospheric Tomography (ClT) model which provides ionosphere tomography images covering five different stations in Alaska along the geomagnetic latitude (50-78 degrees). Then these images are compared with real-time ionosphere tomography images obtained at the HAARP website.1. Introduction -- 2. Coordinate systems overview -- 3. The ionosphere and its monitoring -- 4. GPS total electron content comparisons -- 5. Ionospheric tomography -- 6. Software development -- 7. Summary, conclusions, and future work -- References -- Appendix: NOAA format data file

Partitioned time integration methods for hardware in the loop based on linearly implicit L-Stable Rosenbrock methods

Hardware in the loop based on dynamic substructuring was conceived to be a hybrid numerical-experimental technique to simulate the non-linear behaviour of an emulated structure. Its challenge is to ensure that both numerical and physical substructures interact in real time by means of actuators –transfer systems-. With this objective in mind, the development and implementation of partitioned real-time compatible Rosenbrock algorithms are presented in this paper. In detail, we shortly introduce monolithic linearly implicit L-stable algorithms with two stages; and in view of the analysis of complex emulated structures, we present a novel interfield partitioned algorithm. Both the stability and accuracy properties of the proposed algorithm are examined through analytical and numerical studies carried out on Single-DoF model problems. Moreover, a novel test rig conceived to perform both linear and nonlinear substructure tests is introduced, and tests on a two-DoF split-mass system are illustrated. The drawbacks of this algorithm are underlined and improvements are introduced on a companion solution procedure

Validation of the Parlay API through prototyping

The desire within the telecommunications world for new and faster business growth has been a major drive towards the development of open network API. Over the past 7 years several (semi) standardization groups have announced work on network API, including TINA-C, JAIN, IEEE P1520, INforum, 3GPP, JAIN, Parlay. The Parlay group seems most successful in attracting industry awareness with their API, called the Parlay API. The rational behind the Parlay API is that it attracts innovation from third parties that are outside the network operator's domain to build and deploy new network-hosted applications. This also means that the public telecommunication network is opened for niche and short-lived applications as well as for applications that possibly integrate telephones with other terminals such as PC. The Parlay group has successfully passed the first two phases of success, namely publishing their API on the right moment in time and attracting a critical mass within the telecommunication industry with their results. Prototyping the API on a real network execution platform is the only way to show its technical feasibility. Such an exercise was executed internally within Lucent Technologies and raised a number of questions as well as recommendations on both the technical and the semantical behavior for systems that will be interconnected via the Parlay API. We share these results, showing the drawbacks and advantages as well as challenges for this AP

A Hardware-in-the-Loop Platform for DC Protection

With the proliferation of power electronics, dc-based power distribution systems can be realized; however, dc electrical protection remains a significant barrier to mass implementation dc power distribution. Controller Hardware-in-the-loop (CHiL) simulation enables moving up technology readiness levels (TRL) quickly. This work presents an end-to-end solution for dc protection CHiL for early design exploration and verification for dc protection, allowing for the rapid development of dc protection schemes for both Line-to-Line (LL) and Line-to-Ground (LG) faults. The approach combines using Latency Based Linear Multistep Compound (LB-LMC), a real-time simulation method for power electronic, and National Instruments (NI) FPGA hardware to enable dc protection design with CHiL. A case study is performed for a 1.5 MW Voltage Source Rectifier (VSR) under LL and LG faults in an ungrounded system. The deficiency in real-time simulation resolution of Commercial-off-the-Shelf (COTS) for dc fault transients is shown, and addressed by using LB-LMC RT solver inside NI FPGA hardware to achieve 50 ns resolution of dc fault transients

Leveraging Intellect in a Small Business: Designing an Infrastructure to Support Today's Knowledge Worker

The intensity of competition and pace with which knowledge becomes obsolete are heralding an era where leadership, structure and control systems must increasingly focus on management of knowledge and skills. Such an environment requires management to systematically design an infrastructure that is tailored to the needs of an increasingly mobile knowledge worker and supports organizational learning in areas of strategic concern. Small businesses face  a unique challenge in this environment as they often do not have the time or a sufficient ''mass " of employees to sustain sophisticated recruiting, development or performance management programs. In the following article, the authors argue the real world imperative of crafting an infrastructure that supports organizational learning from the very inception of a business, and provide some manageable approaches to this task for any small business

ESTIMATION OF VEHICLE MASS AND ROAD GRADE

This thesis describes development of a real-time-implementable algorithm for simultaneous estimation of a heavy vehicle\u27s mass and time-varying road grade and its verification with experimental data. Accurate estimate of a heavy vehicle\u27s mass is critical in several vehicle control functions such as in transmission and stability control. The goal is to utilize the standard signals on a vehicle in a model-based estimation strategy, as opposed to a more costly sensor-based approach. The challenge is that unknown road grade complicates model-based estimation of vehicle mass and therefore the time-varying grade should be estimated simultaneously. In addition an estimate of road grade may be used as a feedforward input to transmission control and cruise control systems enhancing their responsiveness. The vehicle longitudinal dynamics model (F=ma) forms the core of this model-based approach. Mathematically this is a single equation with one unknown parameter (mass) and one time-varying input disturbance (grade). The goal is to estimate the constant parameter and time-varying grade by using engine torque and speed, vehicle speed and transmission state. The problem is fundamentally difficult because of i) variation of grade over time ii) lack of ``rich\u27\u27 data during most of vehicle\u27s cruise time, iii) uncertainty about available traction force during gear-shift periods and braking, and iv) low signal-to-noise ratio for vehicle acceleration signal. We have tested two independent estimation schemes using experimental data sets provided by Eaton Corporation. The first algorithm uses recursive least square with two forgetting factors for simultaneous estimation of mass and grade. The second algorithm is a two-stage scheme which cascades a Lyapunov-based nonlinear estimator next to a recursive least square scheme. These algorithms were conceived in our group in the past; however they needed modification and refinements for robust real-time implementation. After these refinements, the modified algorithms are capable of generating estimates for mass and time-varying road grade which are more accurate in realistic scenarios and for most part of the vehicle run. More specifically we are able to generate very accurate estimates of road grade, when the clutch is fully engaged and we have proposed fixes that improve the quality of estimates even during periods of gear change. Provided persistence of excitations we are able to generate accurate estimates of mass which in turn improves the quality of grade estimate. It is important to robustify initialization of algorithm 1 further which is now sensitive to an initial batch size; a task listed in the future work. Algorithm 2 does not rely on an initial batch and therefore is expected to be adopted as the preferred approach for implementation

NASA JSC EV2 Intern Spring 2016 - Jennie Chung

Exploration Mission 2 (EM-2) is a mission to resume the manned exploration of the Solar System. This mission is the first crewed mission of NASAs Orion on the Space Launch System. The target for EM-2 is to perform a flyby of a captured asteroid in lunar orbit, which NASA plans to launch in 2023. As an intern working with EV-2 Avionics Systems Division in Johnson Space Center, we are developing flight instrumentation systems for EM-2 (MISL & RFID). The Modular Integrated Stackable Layer (MISL) is a compact space-related computer system that is modular, scalable and reconfigurable. The RFID (radio frequency identification) sensors are used to take lower frequency (TC) type measurements and be able to stream data real-time to an RF (radio frequency) interrogator upon demand. Our job, in EV-2, is to certify, test, manufacture/assemble and deliver flight EM-2 DFI System (MISL & RFID). Our goal is to propose a development effort to design low-mass wire and wireless data acquisition and sensor solutions for EM-2 DFI (Development Flight Instrumentation). The team is tasked to provide the most effective use of 75 pounds to acquire DFI data and to collect sensor data for 100-200 high priority DFI channels (mass driven)

Wearable Intrinsically Soft, Stretchable, Flexible Devices for Memories and Computing

A recent trend in the development of high mass consumption electron devices is towards electronic textiles (e-textiles), smart wearable devices, smart clothes, and flexible or printable electronics. Intrinsically soft, stretchable, flexible, Wearable Memories and Computing devices (WMCs) bring us closer to sci-fi scenarios, where future electronic systems are totally integrated in our everyday outfits and help us in achieving a higher comfort level, interacting for us with other digital devices such as smartphones and domotics, or with analog devices, such as our brain/peripheral nervous system. WMC will enable each of us to contribute to open and big data systems as individual nodes, providing real-time information about physical and environmental parameters (including air pollution monitoring, sound and light pollution, chemical or radioactive fallout alert, network availability, and so on). Furthermore, WMC could be directly connected to human brain and enable extremely fast operation and unprecedented interface complexity, directly mapping the continuous states available to biological systems. This review focuses on recent advances in nanotechnology and materials science and pays particular attention to any result and promising technology to enable intrinsically soft, stretchable, flexible WMC