An Analysis of Spacecraft Dynamic Testing at the Vehicle Level


Book Description

The US space industry has accumulated a vast amount of expertise in the testing of spacecraft to ensure these vehicles can endure the harsh environments associated with launch and on-orbit operations. Even with this corporate experience, there remains a wide variation in the techniques utilized to test spacecraft during the development and manufacturing process, particularly with regard to spacecraft level dynamics testing. This study investigates the effectiveness of sinusoidal vibration, random vibration, acoustic noise and transient methods of spacecraft dynamic testing. An analysis of test failure and on-orbit performance data for acceptance testing indicates that the acoustic test is the most perceptive workmanship screen at the vehicle level and that additional dynamics tests do not result in an increase in acceptance test effectiveness. For spacecraft qualification, acoustic testing is almost universally employed for qualification in the high frequency environment. For the low frequency environment, data collected from a variety of spacecraft test programs employing sinusoidal sweep, random vibration and transient testing methods shows that a transient base excitation provides the most accurate simulation for the purpose of design verification. Furthermore, data shows that sinusoidal vibration testing provides an unrealistic simulation of the flight environment and results in an increased potential for overtesting.




Spacecraft System Design


Book Description

Drawing on practical engineering experience and latest achievements of space technology in China, this title investigates spacecraft system design and introduces several design methods based on the model development process. A well-established space engineering system with spacecraft as the core is integral to spaceflight activities and missions of entering, exploring, developing and utilizing outer space. This book expounds the key phases in the workflow of spacecraft development, including task analysis, overall plan design, external interface, configuration and assembly design and experimental verification. Subsystems that function as the nuclei of spacecraft design and important aspects in the model development process are then examined, such as orbit design, environmental influence factors, reliability design, dynamics analysis, etc. In addition, it also discusses the digital environment and methods to improve the efficiency of system design. The title will appeal to researchers, students, and especially professionals interested in spacecraft system design and space engineering.




Automatic Control in Aerospace 1992


Book Description

Space vehicles have become increasingly complex in recent years, and the number of missions has multiplied as a result of extending frontiers in the exploration of our planetary system and the universe beyond. The advancement of automatic control in aerospace reflects these developments. Key areas covered in these proceedings include: the size and complexity of spacecrafts and the increasingly stringent performance requirements to be fulfilled in a harsh and unpredictable environment; the merger of space vehicles and airplanes into space planes to launch and retrieve payloads by reusable winged vehicles; and the demand to increase space automation and autonomy to reduce human involvement as much as possible in manned, man-tended and unmanned missions. This volume covers not only the newly evolving key technologies but also the classical issues of guidance, navigation and control.







Spacecraft Dynamics and Control


Book Description

Spacecraft Dynamics and Control: The Embedded Model Control Approach provides a uniform and systematic way of approaching space engineering control problems from the standpoint of model-based control, using state-space equations as the key paradigm for simulation, design and implementation. The book introduces the Embedded Model Control methodology for the design and implementation of attitude and orbit control systems. The logic architecture is organized around the embedded model of the spacecraft and its surrounding environment. The model is compelled to include disturbance dynamics as a repository of the uncertainty that the control law must reject to meet attitude and orbit requirements within the uncertainty class. The source of the real-time uncertainty estimation/prediction is the model error signal, as it encodes the residual discrepancies between spacecraft measurements and model output. The embedded model and the uncertainty estimation feedback (noise estimator in the book) constitute the state predictor feeding the control law. Asymptotic pole placement (exploiting the asymptotes of closed-loop transfer functions) is the way to design and tune feedback loops around the embedded model (state predictor, control law, reference generator). The design versus the uncertainty class is driven by analytic stability and performance inequalities. The method is applied to several attitude and orbit control problems. - The book begins with an extensive introduction to attitude geometry and algebra and ends with the core themes: state-space dynamics and Embedded Model Control - Fundamentals of orbit, attitude and environment dynamics are treated giving emphasis to state-space formulation, disturbance dynamics, state feedback and prediction, closed-loop stability - Sensors and actuators are treated giving emphasis to their dynamics and modelling of measurement errors. Numerical tables are included and their data employed for numerical simulations - Orbit and attitude control problems of the European GOCE mission are the inspiration of numerical exercises and simulations - The suite of the attitude control modes of a GOCE-like mission is designed and simulated around the so-called mission state predictor - Solved and unsolved exercises are included within the text - and not separated at the end of chapters - for better understanding, training and application - Simulated results and their graphical plots are developed through MATLAB/Simulink code




Langley Aerospace Test Highlights, 1988


Book Description

Some of the significant tests which were performed during calendar year 1988 in Langley test facilities, a number of which are unique in the world are highlighted.