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Machines, Volume 1, Issue 1 (June 2013), Pages 1-62

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Research

Open AccessArticle OpenOrbiter: A Low-Cost, Educational Prototype CubeSat Mission Architecture
Machines 2013, 1(1), 1-32; doi:10.3390/mach1010001
Received: 16 December 2012 / Accepted: 21 January 2013 / Published: 24 January 2013
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Abstract
The preliminary design for the Open Prototype for Educational NanoSats (OPEN) demonstration spacecraft, OpenOrbiter, is presented. OPEN is designed to facilitate the formation of CubeSat development programs nationally and worldwide via providing a publically-available set of spacecraft design documents, implementation and testing plans.
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The preliminary design for the Open Prototype for Educational NanoSats (OPEN) demonstration spacecraft, OpenOrbiter, is presented. OPEN is designed to facilitate the formation of CubeSat development programs nationally and worldwide via providing a publically-available set of spacecraft design documents, implementation and testing plans. These documents should allow the creation of a 1-U CubeSat with a parts budget of approximately $ 5,000. This allows spacecraft development to be incorporated in regular curriculum and supported from teaching (as opposed to research) funds. The OPEN design, implemented by OpenOrbiter, has an innovative internal structure, separates payload and operations processing and includes features to ease and highlight errors in integration. Full article
Open AccessArticle Multiple Estimation Architecture in Discrete-Time Adaptive Mixing Control
Machines 2013, 1(1), 33-49; doi:10.3390/machines1010033
Received: 11 March 2013 / Revised: 29 April 2013 / Accepted: 20 May 2013 / Published: 29 May 2013
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Abstract
Adaptive mixing control (AMC) is a recently developed control scheme for uncertain plants, where the control action coming from a bank of precomputed controller is mixed based on the parameter estimates generated by an on-line parameter estimator. Even if the stability of the
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Adaptive mixing control (AMC) is a recently developed control scheme for uncertain plants, where the control action coming from a bank of precomputed controller is mixed based on the parameter estimates generated by an on-line parameter estimator. Even if the stability of the control scheme, also in the presence of modeling errors and disturbances, has been shown analytically, its transient performance might be sensitive to the initial conditions of the parameter estimator. In particular, for some initial conditions, transient oscillations may not be acceptable in practical applications. In order to account for such a possible phenomenon and to improve the learning capability of the adaptive scheme, in this paper a new mixing architecture is developed, involving the use of parallel parameter estimators, or multi-estimators, each one working on a small subset of the uncertainty set. A supervisory logic, using performance signals based on the past and present estimation error, selects the parameter estimate to determine the mixing of the controllers. The stability and robustness properties of the resulting approach, referred to as multi-estimator adaptive mixing control (Multi-AMC), are analytically established. Besides, extensive simulations demonstrate that the scheme improves the transient performance of the original AMC with a single estimator. The control scheme and the analysis are carried out in a discrete-time framework, for easier implementation of the method in digital control. Full article
(This article belongs to the Special Issue Advances in Control Engineering)
Figures

Open AccessArticle Mass Estimate for a Lunar Resource Launcher Based on Existing Terrestrial Electromagnetic Launchers
Machines 2013, 1(1), 50-62; doi:10.3390/machines1010050
Received: 16 May 2013 / Revised: 9 June 2013 / Accepted: 12 June 2013 / Published: 20 June 2013
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Abstract
Economic exploitation of lunar resources may be more efficient with a non-rocket approach to launch from the lunar surface. The launch system cost will depend on its design, and on the number of launches from Earth to deliver the system to the Moon.
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Economic exploitation of lunar resources may be more efficient with a non-rocket approach to launch from the lunar surface. The launch system cost will depend on its design, and on the number of launches from Earth to deliver the system to the Moon. Both of these will depend on the launcher system mass. Properties of an electromagnetic resource launcher are derived from two mature terrestrial electromagnetic launchers. A mass model is derived and used to estimate launch costs for a developmental launch vehicle. A rough manufacturing cost for the system is suggested. Full article

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