| 1. |
- Siddiqi, Afreen, et al.
(författare)
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Reconfigurability in planetary surface vehicles : Modelling approaches and case study
- 2006
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Ingår i: JBIS - Journal of the British Interplanetary Society. - London : British Interplanetary Society. - 0007-084X. ; 59:12, s. 450-460
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Tidskriftsartikel (refereegranskat)abstract
- Reconfigurability is being recognized as increasingly important for space systems for reasons of efficiency, extensibility and mission robustness. Planetary Surface Vehicles (PSVs), that may be used in future manned exploration missions, can especially benefit from reconfigurability. Two frameworks for studying reconfigurable systems are proposed that allow for analyzing systems that undergo changes over time. The first framework, using Non-Homogeneous Markov Models (NHMM), allows for identifying useful configurations or states. The second framework, based on control theory, enables issues such as reconfiguration time, and dynamics of the reconfiguration process to be assessed. The application of these models is shown for a PS V in a future human exploration mission that can reconfigure to respond to changing terrain conditions. The results for the specific case considered show that reconfigurability improves the performance of the vehicle over the course of a simulated sortie by approximately 30%.
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| 2. |
- Simpson, Timothy W., et al.
(författare)
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Platform-based design and development : Current trends and needs in industry
- 2006
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Ingår i: Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference - 2006. - New York, : American Society of Mechanical Engineers. ; , s. 801-810
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Konferensbidrag (refereegranskat)abstract
- Many companies constantly struggle to find cost-effective solutions to satisfy the diverse demands of their customers. In this paper, we report on two recent industry-focused conferences that emphasized platform design, development, and deployment as a means to increase variety, shorten lead-times, and reduce development and production costs. The first conference, Platform Management for Continued Growth, was held November-December 2004 in Atlanta, Georgia, and the second, 2005 Innovations in Product Development Conference - Product Families and Platforms: From Strategic Innovation to Implementation, was held in November 2005 in Cambridge, Massachusetts. The two conferences featured presentations from academia and more than 20 companies who shared their successes and frustrations with platform design and deployment, platform-based product development, and product family planning. Our intent is to provide a summary of the common themes that we observed in these two conferences. Based on this discussion, we extrapolate upon industry's needs in platform design, development, and deployment to stimulate and catalyze future work in this important area of research.
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| 3. |
- Sou, Kin Cheong, et al.
(författare)
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Fast time-domain simulation for large-order linear time-invariant state space systems
- 2005
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Ingår i: International Journal for Numerical Methods in Engineering. - : Wiley. - 0029-5981 .- 1097-0207. ; 63:5, s. 681-708
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Tidskriftsartikel (refereegranskat)abstract
- Time-domain simulation is essential for both analysis and design of complex systems. Unfortunately, high model fidelity leads to large system size and bandwidths, often causing excessive computation and memory saturation. In response we develop an efficient scheme for large-order linear time-invariant systems. First, the A matrix is block diagonalized. Then, subsystems of manageable dimensions and bandwidth are formed, allowing multiple sampling rates. Each subsystem is then discretized using a O(n(s)) scheme, where n(s) is the number of states. Subsequently, a sparse matrix O(n(s)) discrete-time system solver is employed to compute the history of the state and output. Finally, the response of the original system is obtained by superposition. In practical engineering applications, closing feedback loops and cascading filters can hinder the efficient use of the simulation scheme. Solutions to these problems are addressed in the paper. The simulation scheme, implemented as a MATLAB function fast1sim, is benchmarked against the standard LTI system simulator 1sim and is shown to be superior for medium to large systems. The algorithm scales close to O(n(s)(2)) for a set of benchmarked systems. Simulation of a high-fidelity model (n ≈ 2200) of the Space Interferometry Mission spacecraft illustrates real world application of the method.
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