The future of deep space exploration depends upon technological advancement towards improving spacecraft's autonomy and versatility. This study aims to examine the feasibility of autonomous orbit ...determination using advanced accelerometer measurements. The objective of this research is to ascertain specific sensor requirements to meet pre‐defined mission navigation error budgets. Traditional inertial navigation (dead reckoning and external aiding) is not considered. Instead, measurements from pairs of advanced, highly sensitive accelerometers (e.g., cold atom accelerometers) are used onboard to determine gravity field gradients, which are then correlated to onboard gravity maps and used to determine orbital information. Linear Covariance Theory helps to efficiently conduct an error budget analysis of the system. This error budget analysis helps to determine the effect of specific error sources in the sensor measurements, thereby providing information to rank and compare relevant sensor parameters and determine an optimal sensor configuration for a given space mission. The procedure is repeated to evaluate different accelerometer configurations and sensor parameters.
Digital devices and ubiquitous online access contribute to the nature and amount of digital labour conducted by school staff. Drawing on more than 40 interviews with staff at one Australian secondary ...school, the general nature of this digital labour is presented, then Clancy's notion of temporal autonomous spaces is introduced and applied to theorise why some teachers used digital technologies constantly in their teaching. The article highlights how some teachers invested their time in learning about and using digital technologies because it enhanced their sense of autonomy and increased their sense of freed time. It theorises how teachers who invest their time into developing their knowledge and effective use of digital technologies in their teaching practice do so because of the perceived benefits that temporal autonomous space brings. Therefore, their practice is sustained as a high temporal priority.
For the past four years autonomous spaces that vary in nature but are run by virtually the same group of people have been operating in Kaunas, Lithuania. In the Lithuanian context, they are one of ...the most prominent recent attempts at continuous radical leftist political infrastructure. In the Central and Eastern European context, they are peculiar for not being connected to public housing struggles. This article draws an outline of their modes of operation and paradigmatic shifts by examining their history as well as theoretical and sociological material and using extensive interviews conducted with participants. Awareness of the complicated relation between meaningful separation and broader participation is suggested as a reflexive means of becoming hubs of political involvement.
The research attempts to deal with the autonomous space systems incorporating new automated maneuvers strategies in the presence of parameters uncertainties. The main subject behind the investigation ...is to realize the high-resolution small amplitude orbital maneuvers via the first control strategy. And subsequently to realize the large amplitude orbital maneuvers via the second control strategy, as well. There is a trajectory optimization to provide the three-axis referenced commends for the aforementioned overactuated autonomous space system to be able to transfer from the initial orbit to its final ones, in finite burn, as long as the uncertainties of key parameters of the system such as the thrust vector, the center of the gravity, the moments of the inertia and so on are taken into real consideration. The strategies performances are finally considered through a series of experiments and a number of benchmarks to be tangibly verified.
•A number of automated maneuvers strategies are designed.•A set of parameters uncertainties of the system are considered.•A trajectory optimization is proposed to deal with the orbital process.•A series of experiments are carried out to verify the investigated outcomes.
The research addresses a Lyapunov-based constrained control strategy to deal with the autonomous space system in the presence of large disturbances. The aforementioned autonomous space system under ...control is first represented through a dynamics model and subsequently the proposed control strategy is fully investigated with a focus on the three-axis detumbling and the corresponding pointing mode control approaches. The three-axis detumbling mode control approach is designed to deal with the unwanted angular rates of the system to be zero, while the saturations of the actuators are taken into consideration. Moreover, the three-axis pointing mode control approach is designed in the similar state to deal with the rotational angles of the system to be desirable. The contribution of the research is mathematically made to propose a control law in connection with a new candidate of Lyapunov function to deal with the rotational angles and the related angular rates of the present autonomous space system with respect to state-of-the-art. A series of experiments are carried out to consider the efficiency of the proposed control strategy, as long as a number of benchmarks are realized in the same condition to verify and guarantee the strategy performance in both modes of control approaches.
•A class of autonomous space systems is considered in the presence of large disturbances.•A Lyapunov-based constrained control strategy is proposed to deal with the angular rotations and the angular rates.•A number of control approaches including the detumbling and the pointing are realized.•A series of experiments is carried out with different scenarios to consider the strategy efficiency.
Physiological and methodological principles of the organization of physical training (PT) and its computerization during a space flight to Mars under the conditions of autonomous activity of the ...crew, including interaction with onboard medical systems, self-maintenance of health, preventive measures, diagnostic examinations, and, if necessary, treatment, are discussed. The conditions of unusually long-term autonomous space flights make the ground-based monitoring of the state of health of crew members substantially more difficult, which calls for computerization of the control over the crew members' health, including prophylactic measures. The situation is further complicated because it is impossible to receive the necessary information from, and transmit it to, the spacecraft in a real-time mode or to quickly return the crew to Earth in case of an emergency. Under these conditions, physical prevention should be based on an onboard automated expert system ensuring the control over the activities of all crew members aimed at optimizing their psychophysical state. The problems of the control of training, including the use of an onboard automated expert system, are discussed.
This paper describes an end-to-end control system for autonomous navigation of a small vehicle at a remote place, e.g. in space for planetary exploration. Due to a realistic background of this study ...the
proposed method has to deal with limited knowledge about the environment as well as limited system resources and operational boundary conditions, especially a very large time delay in the communication
between the ground control station and the space segment. To overcome these constraints the remote system has to act in a very autonomous way. Ground support minimizes the computational load of the remote
system. High-level information interchange reduces the communication bandwidth requirements.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
This study addresses the issue of vision-based navigation for space rendezvous with non-cooperative targets. After a brief description of the scenario and its peculiarities, the theory underlying ...monocular edges-based tracking for pose estimation is recalled and an innovative tracking algorithm is formally developed and implemented. This algorithm is coupled with a dynamic Kalman Filter propagating the dynamics which underlies a space rendezvous. The navigation filter increases the robustness of target position and attitude estimation, and allows the estimation of target translational velocity and rotation rate using only pose measurements. Moreover, the filter implements a computationally efficient delay management technique that allows merging the delayed and infrequent measurements typical of vision-based navigation. The performance of the algorithm is tested in different scenarios with high fidelity synthetic images.
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