Manned Venus Flyby

This study is one of several being conducted at Bellcomm and in Manned Space Flight whose purpose is to give guidance to the Apollo Applications Program's technical objectives by focusing on a longer range goal. The assumed mission in this case is a three-man flyby of Venus launched in November, 1973 on a single standard Saturn V. The selected flight configuration includes a Command and Service Module similar in some respects to Apollo, an Environmental Support Module which occupies the adapter area and a spent S-IVB stage which is utilized for habitable volume and structural support of a solar cell electrical power system. The total injected weight, 106,775 lbs., is within the capability of a single Saturn V of the early 1970's. The study is focused on the selection of subsystem technologies appropriate to long duration flight. The conclusions are reported in terms of the technical characteristics to be achieved as part of the Apollo Applications Program's long duration objectives

Solving the nearest rotation matrix problem in three and four dimensions with applications in robotics

Aplicat embargament des de la data de defensa fins ei 31/5/2022Since the map from quaternions to rotation matrices is a 2-to-1 covering map, this map cannot be smoothly inverted. As a consequence, it is sometimes erroneously assumed that all inversions should necessarily contain singularities that arise in the form of quotients where the divisor can be arbitrarily small. This misconception was clarified when we found a new division-free conversion method. This result triggered the research work presented in this thesis. At first glance, the matrix to quaternion conversion does not seem to be a relevant problem. Actually, most researchers consider it as a well-solved problem whose revision is not likely to provide any new insight in any area of practical interest. Nevertheless, we show in this thesis how solving the nearest rotation matrix problem in Frobenius norm can be reduced to a matrix to quaternion conversion. Many problems, such as hand-eye calibration, camera pose estimation, location recognition, image stitching etc. require finding the nearest proper orthogonal matrix to a given matrix. Thus, the matrix to quaternion conversion becomes of paramount importance. While a rotation in 3D can be represented using a quaternion, a rotation in 4D can be represented using a double quaternion. As a consequence, the computation of the nearest rotation matrix in 4D, using our approach, essentially follow the same steps as in the 3D case. Although the 4D case might seem of theoretical interest only, we show in this thesis its practical relevance thanks to a little known mapping between 3D displacements and 4D rotations. In this thesis we focus our attention in obtaining closed-form solutions, in particular those that only require the four basic arithmetic operations because they can easily be implemented on microcomputers with limited computational resources. Moreover, closed-form methods are preferable for at least two reasons: they provide the most meaningful answer because they permit analyzing the influence of each variable on the result; and their computational cost, in terms of arithmetic operations, is fixed and assessable beforehand. We have actually derived closed-form methods specifically tailored for solving the hand-eye calibration and the pointcloud registration problems which outperform all previous approaches.Dado que la función que aplica a cada cuaternión su matrix de rotación correspondiente es 2 a 1, la inversa de esta función no es diferenciable en todo su dominio. Por consiguiente, a veces se asume erróneamente que todas las inversiones deben contener necesariamente singularidades que surgen en forma de cocientes donde el divisor puede ser arbitrariamente pequeño. Esta idea errónea se aclaró cuando encontramos un nuevo método de conversión sin división. Este resultado desencadenó el trabajo de investigación presentado en esta tesis. A primera vista, la conversión de matriz a cuaternión no parece un problema relevante. En realidad, la mayoría de los investigadores lo consideran un problema bien resuelto cuya revisión no es probable que proporcione nuevos resultados en ningún área de interés práctico. Sin embargo, mostramos en esta tesis cómo la resolución del problema de la matriz de rotación más cercana según la norma de Frobenius se puede reducir a una conversión de matriz a cuaternión. Muchos problemas, como el de la calibración mano-cámara, el de la estimación de la pose de una cámara, el de la identificación de una ubicación, el del solapamiento de imágenes, etc. requieren encontrar la matriz de rotación más cercana a una matriz dada. Por lo tanto, la conversión de matriz a cuaternión se vuelve de suma importancia. Mientras que una rotación en 3D se puede representar mediante un cuaternión, una rotación en 4D se puede representar mediante un cuaternión doble. Como consecuencia, el cálculo de la matriz de rotación más cercana en 4D, utilizando nuestro enfoque, sigue esencialmente los mismos pasos que en el caso 3D. Aunque el caso 4D pueda parecer de interés teórico únicamente, mostramos en esta tesis su relevancia práctica gracias a una función poco conocida que relaciona desplazamientos en 3D con rotaciones en 4D. En esta tesis nos centramos en la obtención de soluciones de forma cerrada, en particular aquellas que solo requieren las cuatro operaciones aritméticas básicas porque se pueden implementar fácilmente en microcomputadores con recursos computacionales limitados. Además, los métodos de forma cerrada son preferibles por al menos dos razones: proporcionan la respuesta más significativa porque permiten analizar la influencia de cada variable en el resultado; y su costo computacional, en términos de operaciones aritméticas, es fijo y evaluable de antemano. De hecho, hemos derivado nuevos métodos de forma cerrada diseñados específicamente para resolver el problema de la calibración mano-cámara y el del registro de nubes de puntos cuya eficiencia supera la de todos los métodos anteriores.Postprint (published version

ACS Without an Attitude

The book (ACS without an Attitude) is an introduction to spacecraft attitude control systems. It is based on a series of lectures that Dr. Hallock presented in the early 2000s to members of the GSFC flight software branch, the target audience being flight software engineers (developers and testers), fairly new to the field that desire an introductory understanding of spacecraft attitude determination and control

Kinematics nomenclature for physiological accelerations with special reference to vestibular applications

Kinematics nomenclature for physiological accelerations and special reference to vestibular apparatu

AAS/GSFC 13th International Symposium on Space Flight Dynamics

This conference proceedings preprint includes papers and abstracts presented at the 13th International Symposium on Space Flight Dynamics. Cosponsored by American Astronautical Society and the Guidance, Navigation and Control Center of the Goddard Space Flight Center, this symposium featured technical papers on a wide range of issues related to orbit-attitude prediction, determination, and control; attitude sensor calibration; attitude dynamics; and mission design

On-Manifold Preintegration for Real-Time Visual-Inertial Odometry

Current approaches for visual-inertial odometry (VIO) are able to attain highly accurate state estimation via nonlinear optimization. However, real-time optimization quickly becomes infeasible as the trajectory grows over time, this problem is further emphasized by the fact that inertial measurements come at high rate, hence leading to fast growth of the number of variables in the optimization. In this paper, we address this issue by preintegrating inertial measurements between selected keyframes into single relative motion constraints. Our first contribution is a \emph{preintegration theory} that properly addresses the manifold structure of the rotation group. We formally discuss the generative measurement model as well as the nature of the rotation noise and derive the expression for the \emph{maximum a posteriori} state estimator. Our theoretical development enables the computation of all necessary Jacobians for the optimization and a-posteriori bias correction in analytic form. The second contribution is to show that the preintegrated IMU model can be seamlessly integrated into a visual-inertial pipeline under the unifying framework of factor graphs. This enables the application of incremental-smoothing algorithms and the use of a \emph{structureless} model for visual measurements, which avoids optimizing over the 3D points, further accelerating the computation. We perform an extensive evaluation of our monocular \VIO pipeline on real and simulated datasets. The results confirm that our modelling effort leads to accurate state estimation in real-time, outperforming state-of-the-art approaches.Comment: 20 pages, 24 figures, accepted for publication in IEEE Transactions on Robotics (TRO) 201

Aerospace medicine and biology: A continuing bibliography with indexes, supplement 129, June 1974

This special bibliography lists 280 reports, articles, and other documents introduced into the NASA scientific and technical information system in May 1974