Papers by Keyword: Spacecraft

Abstract: This for a spacecraft undergoing a continuous thruster maneuver, the spacecraft mass changes due to fuel consumption, and the liquid sloshing has time-varying property. However, the conventional applications in prior literature took these time-varying properties into consideration barely. The characteristics of residual fuel become an important drive for the coupled solid-liquid dynamics, especially in a partially filled tank. In this paper, dynamic equations of an equivalent pendulum model with variable parameters were developed by Lagrangian method. The calculation results showed that the time-varying properties influence the sloshing characteristics significantly. Finally, influences of draining flow rates, the thrust press during the sloshing motions, sloshing induced forces and torques were also investigated. The investigations here provided an effective way to deal with the delicate problem and to reveal the characteristics of the liquid sloshing dynamics in partially filled tank of a spacecraft.

Abstract: Even though carbon/epoxy composite materials have been widely used in aircraft for many years, different requirements are often required for composite materials in spacecraft application due to the space environment. Some of the considerations include modulus and thermal properties for spacecraft while as strength is important for aircraft. For heat pipe panels, space radiator, antennas or optical benches, thermal stability is required for the life of the satellite. In this study, long term creep behavior of high performance composite material is investigated with time-temperature shift factor. The fiber is pitch-based carbon which shows high thermal conductivity and high modulus. It was possible to predict creep compliance after 5 years from dynamic mechanical analysis data. This information is useful to understand the property change during the intended service life of the spacecraft.

Abstract: The problem of the dynamics of space lander landing on the surface of a celestial body with small gravitational field is considered in this paper. This report presents a sustainable solution to the problem of landing on a small celestial body based on the use of special pinch engines. The thrust value of pinch engines is considered to be constant in process of operation. The optimal time of inclusion of works of pinch engines, working conditions to ensure the stability of landing lander on the surface of small celestial bodies is defined in this paper, and influence of the thrust value of pinch engines on the stability of landing also investigated in this paper. The minimum value of the ratio of engine thrust to weight of space lander, at which make landing reliable and stable is presented.

Abstract: The standardized design of space products has become significant since the fast development of pace technology. Currently, the space products are mostly designed separately which brings the fact that the interfaces of these products differ from each other, thus it obstructs the quick integration and test. In order to deal with this issue, this paper presents the reconfigurable unit to unify the diverse interfaces and the application of this method can satisfy the demand of different space missions, thus the research and development period and the cost can be reduced.

Abstract: For complex spacecraft assembly conditions, how to play effective and flexible robotic characteristics, and improve production efficiency, is the problem needed to solve.this paper presents a flexible force control method on robotic assembly: a 6-axis force/torque sensor is mounted between tools and the end of robots, the operator operates the load by hands directly, and the system can obtain the force/torque information caused by operator’s hands through gravity compensation algorithm, then the force/torque information is used as input parameters to control the robots moving with the hands. The detailed scheme and algorithms are presented in this paper.

Abstract: The nonlinear backstepping adaptive controller is designed for the large angle fast attitude maneuver of spacecraft with uncertainties in the moment of inertia. Deviation between the actual position and command position is depicted by error quaternion. The nonlinear backstepping tracking function is employed to design the adaptive controller both of command torque and estimation of unknown moment inertia. And the stability is analyzed based on Lyapunovo function. By Matlab/Simulink programming, the simulation of spacecraft attitude manoeuver control is discussed, and its results demonstrate the effectiveness and feasibility of the proposed controller.

Abstract: Critical parameters of the bypass device thermocouple made of SME alloy are optimized on the base of the developed thermal model of Lithium-Ion storage battery (LISB) for space applications. It is shown that the terminal is the most dangerous element within LIAB. To ensure LIAB reliability in case of one cell failure, a temperature limit in the vicinity of the terminal is set to 100°C, and the bypass device action time – to 2–3 s, which corresponds to phase transitions temperature range of the thermocouple spring made of SME alloy.

Abstract: Based on the growing on-orbit servicing technology, replaceable techniques have been proposed agenda. Replaceable plug body is designed for such demand. On the basis of the structural design of the plug body, the kinetic analysis of the mechanism is made in ADAMS to test the feasibility of the structure. Establish Euler-Lagrange equations of the system to determine the impact of total energy of connecting rod on the mechanism, make great analysis to ensure that there is no coupling phenomenon, and optimize the design parameters.

Abstract: Random vibration is one of dynamic environments of spacecraft during launch. In engineering, design load was usually equivalent static load based on acceleration. A new equivalent static load based on strain or stress was presented by the writer. To validate the new equivalent static design method, random vibration test was designed including test article and test specification, and signal processing was in time domain; static test was designed to compare static yield strength and dynamic yield strength, and dynamic yield strength was 50% -80% higher than static yield strength; measured data in time domain was analyzed , and the equivalent static design of strain based on first passage model can be used to spacecraft structure design. And it will decrease the mass of spacecraft structure obviously.

Abstract: Spacecraft surface charge and discharge is an important reason for the failure of the spacecraft in the space environment. This paper introduces the principle of spacecraft surface charging and discharging , from the spacecraft surface charging discharging phenomenon found to the harm of charge and discharge, elaborated the spacecraft surface charging protection method.