Traditionally, star sensors have used fairly large fields of view and bright stars to perform tra... more Traditionally, star sensors have used fairly large fields of view and bright stars to perform tracking and identification. Recent trends in space missions have brought out the need for smaller field-of-view sensors, capable of performing multiple functions that will reduce ...
In order to develop optimize star sensing and star identification with re- spect to continues ope... more In order to develop optimize star sensing and star identification with re- spect to continues operation and reliability, the concept of star catalogs with near uniform angular spacing between stars arises. Such catalogs are not characterized by the usual constant magnitude cutos. With a uniform star catalog we want to build a reference star catalog where the expectation of the
A system and method for using two authenticators to identify a player in a gaming environment is ... more A system and method for using two authenticators to identify a player in a gaming environment is disclosed, where the second authenticator is based on biometric data. The two authenticators allow a two-level authorization process providing very high assurance that a player at a gaming machine is who they claim to be, and where the second authenticator, being based on biometric data, enables a player to quickly and easily authenticate documents and/or authenticate age while continuing to play at game machines.
IEEE Transactions on Aerospace and Electronic Systems, 2008
ABSTRACT Star trackers are the most accurate attitude sensors to perform 3-axis attitude estimati... more ABSTRACT Star trackers are the most accurate attitude sensors to perform 3-axis attitude estimation of spacecraft. However, even though they are specifically designed to estimate attitude, they can also be used to estimate the local coordinates of the camera on the Earth as well as the direction of East. This requires us to align the camera optical axis with the local direction of the gravity and to have knowledge of the time, that can be provided by an accurate clock. The resulting system is the Compass Star Tracker (CST), that is, a star tracker used as a global surface navigation system. This system would certainly not substitute the Global Positioning System which, in turn, does not suffer of the limitation night-only operation and in clear weather conditions. On the contrary, the CST does not require any satellite information or other support from ground stations to be used in lieu of the traditional Global Positioning System.
12th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference, 2008
ABSTRACT This paper presents a robust algorithm for solving nonlinear equality constrained opti- ... more ABSTRACT This paper presents a robust algorithm for solving nonlinear equality constrained opti- mization problems by introducing a globally convergent homotopy method. The �rst order necessary condition for the equality constrained optimization is expressed as an orthogonal condition between the performance gradient vector and the null space vectors of the con- straint Jacobian matrix. By constructing a nonlinear system of equations consisting of the �rst order condition and the constraints, we utilize a probability-one homotopy method to search along the zero curve of the homotopy and solve for the optimal solution. Be- cause the integrated homotopy solution never leaves the constrained surface, the proposed algorithm needs neither a penalty function nor Lagrangian multipliers for �nding optimal solutions. The root solution histories are smooth and no arti�cial behaviors are introduced to force the satisfaction of the constraints. No Taylor expansions are introduced for either the performance index or the constraints so no problems arise because of approximated model assumptions. Several examples which could not be solved using `fmincon', which is a nonlinear optimization function in MATLAB7.0.1, are presented to demonstrate very encouraging results from the proposed algorithm.
Traditionally, star sensors have used fairly large fields of view and bright stars to perform tra... more Traditionally, star sensors have used fairly large fields of view and bright stars to perform tracking and identification. Recent trends in space missions have brought out the need for smaller field-of-view sensors, capable of performing multiple functions that will reduce ...
In order to develop optimize star sensing and star identification with re- spect to continues ope... more In order to develop optimize star sensing and star identification with re- spect to continues operation and reliability, the concept of star catalogs with near uniform angular spacing between stars arises. Such catalogs are not characterized by the usual constant magnitude cutos. With a uniform star catalog we want to build a reference star catalog where the expectation of the
A system and method for using two authenticators to identify a player in a gaming environment is ... more A system and method for using two authenticators to identify a player in a gaming environment is disclosed, where the second authenticator is based on biometric data. The two authenticators allow a two-level authorization process providing very high assurance that a player at a gaming machine is who they claim to be, and where the second authenticator, being based on biometric data, enables a player to quickly and easily authenticate documents and/or authenticate age while continuing to play at game machines.
IEEE Transactions on Aerospace and Electronic Systems, 2008
ABSTRACT Star trackers are the most accurate attitude sensors to perform 3-axis attitude estimati... more ABSTRACT Star trackers are the most accurate attitude sensors to perform 3-axis attitude estimation of spacecraft. However, even though they are specifically designed to estimate attitude, they can also be used to estimate the local coordinates of the camera on the Earth as well as the direction of East. This requires us to align the camera optical axis with the local direction of the gravity and to have knowledge of the time, that can be provided by an accurate clock. The resulting system is the Compass Star Tracker (CST), that is, a star tracker used as a global surface navigation system. This system would certainly not substitute the Global Positioning System which, in turn, does not suffer of the limitation night-only operation and in clear weather conditions. On the contrary, the CST does not require any satellite information or other support from ground stations to be used in lieu of the traditional Global Positioning System.
12th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference, 2008
ABSTRACT This paper presents a robust algorithm for solving nonlinear equality constrained opti- ... more ABSTRACT This paper presents a robust algorithm for solving nonlinear equality constrained opti- mization problems by introducing a globally convergent homotopy method. The �rst order necessary condition for the equality constrained optimization is expressed as an orthogonal condition between the performance gradient vector and the null space vectors of the con- straint Jacobian matrix. By constructing a nonlinear system of equations consisting of the �rst order condition and the constraints, we utilize a probability-one homotopy method to search along the zero curve of the homotopy and solve for the optimal solution. Be- cause the integrated homotopy solution never leaves the constrained surface, the proposed algorithm needs neither a penalty function nor Lagrangian multipliers for �nding optimal solutions. The root solution histories are smooth and no arti�cial behaviors are introduced to force the satisfaction of the constraints. No Taylor expansions are introduced for either the performance index or the constraints so no problems arise because of approximated model assumptions. Several examples which could not be solved using `fmincon', which is a nonlinear optimization function in MATLAB7.0.1, are presented to demonstrate very encouraging results from the proposed algorithm.
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Papers by John Junkins