Abstract: Improving the standards of the launch mechanisms and cutting down the launching costs is the prime objective here.
Abstract: The spacecraft-Pioneer 10 is the first man-made object which flew out of the solar system, you never get it back; the outer space adventure makes Human observe nine planets at close hand by means of the periodic return of Halley Comet, you may get it back. The outer space adventure by the Halley Comet which is safe, economic and environmental protection can explore extraterrestrial civilization.
Abstract: Based on time-varying characters of spacecraft propulsion system, which generates tremendous difficulty to establish diagnostic criteria artificially, the fault isolation method based on Analytical Redundancy Relations (ARRs) generating from Diagnostic Bond Graph (DBG) has been proposed. The ARRs for Spacecraft Propulsion System are built on time-invariant structural characters, which can overcome the challenges from artificially establishing time-varying diagnostic criteria beforehand. By the tendency analysis of the residuals of ARRs, the fault signature matrix can be established. Then faults are isolated by comparison of observed signature and fault signature. Through the analysis of isolation results of a spacecraft propulsion system, it shows that ARRs is valid and practicable at fault isolation with rapid rates.
Abstract: The main aim of this work was to construct and investigate an optical and electromagnetic coupling thruster for spacecraft propulsion. This thruster, called as laser-electromagnetic coupling plasma thruster (LEMPT), ablates solid propellants, ionizing the gaseous matter and forming a plasma jet to export impulse bit for the spacecraft. Firstly, tests were performed analyzing the influence of physical variables (initial voltage bias of capacitors, i.e., storage energy of capacitors and laser output repetition frequency) on the discharge characteristics which represents the performance of the thruster. Secondly, the stability quality of the thruster is tested and evaluated in experiment. Ethylene-vinyl acetate copolymer (known as EVA) is used as a propellant for the thruster in the experiments herein. The results have shown that this LEMPT can be used for spacecraft in the future.
Abstract: Experimental studies have been carried out using the in-house developed propellant samples at the atmospheric conditions to examine the influence of propellant surface orientation / attitude on burn rate. A series of burning tests are conducted with different grain orientations, viz., vertical, inverted and horizontal. We have observed 5 % burn rate augmentation on end-burning grains when the burning surface evolution was against the earth gravity compared to the normal vertical candle burning condition. We conjectured that the coupled effects of the instantaneous variations of the propellant burning surface attitude and the flight acceleration during the mission could alter the flame structure due to the local gravitational influence, which in turn alter the burn rate. This paper throws light for developing a suitable gravitational force dependant burn rate model for improving the performance prediction of solid rocket motors for aerospace applications.
Abstract: Inserting a satellite into different orbit of injection orbit require an orbital maneuver. In addition, the orbit maneuver needs a suitable control of upper stage. Providing required angles is the duty of this control and it must be able to come over disturbances. This paper, with looking over Attitude Control Systems (ACS) used in upper stages, introduces an algorithm for design and sizing of upper stage`s ACS considering requirements and constraints. The algorithm derives required ACS propellant mass, tanks value, feeding pressure, amount of thrust, combustion chamber pressure and total mass of ACS. Presented algorithm needs minimum inputs and estimates the outputs using accuracy experimental functions and scientific theorems. Finally the algorithm is validated by some real cases.
Abstract: In order to study the influence of electrode flare angle on the performance of Ablation Pulsed Plasma Thruster. Discharge character, plasma velocity and performance over different electrode flare angles of the Pulsed Plasma Thruster at 13.5J initial energy are measured experimentally, the effect of electrode flare angle on the electrode inductance gradient, equivalent circuit parameters and energy transfer efficiency are analyzed. It can be seen that the circuit parameters and inductance distribution are changed with electrode flare angle, the impulse bit, specific impulse, thruster efficiency and mean exhaust velocity increase non-linearly with flare angle increasing from 0 degree to 27 degree and the Pulsed Plasma Thruster gets the maximum thruster performance at 27 degree flare angle. It shows that with the increase of electrode flare angle the fraction of ablated mass accelerated magnetically and the impulse bit created by Lorentz force decrease are the reasons inducing the change in thruster performance.
Abstract: Signed Directed Graph (SDG) has been widely applied to model the cause and effect behavior of process systems in recent years. However, SDG-based diagnosis has poorly discriminatory ability, because of the information loss while going from quantitative to qualitative domain. In this paper, a new method combining SDG with quantitative knowledge is presented to improve the discriminatory ability. In the method, a hybrid reasoning (forward and backward) strategy based on assumption and verification was applied to find all the potential fault sources and corresponding consistent paths in SDG model. Then the SDG-based method was modified by integrating governing equation and temporal information of the system, in order to improve the discriminatory ability. The method has been validated by the artificial telemetry data, and the effectiveness of the method has been confirmed. The method proposed can provide important practical value for the development of on-board fault diagnosis system of spacecraft propulsion systems.
Abstract: This research reports on error identification and compensation of a special purpose CNC machine. The kinematic model of the machine was developed using rigid body kinematics and small angle approximation of the axes of the machine through homogenous transform matrices, and the equations describing the volumetric errors. The machine was calibrated to measure the axes errors, which were used in the kinematic model in order to determine compensation values. The model was evaluated by means of direct measurements of axis movements using a laser interferometer, as well as in cutting tests, where a large number of holes were drilled in plates and measured with a CMM. The results showed that the developed model achieved an average error reduction of 40%, for the X and Y axes.
Abstract: This paper is related to the development of ASIC for tactile sensing system in humanoid robots. First of all, it is necessary to choose the best sensor for tactile sensing in humanoid robots. A large number of sensors like capacitive, resistive, piezoresistive, tunnel effective, optical, ultrasonic, magnetism based, piezoelectric sensors are available in market for tactile sensing. Not all the sensors are suitable for tactile sensing at all locations of humanoid robotics. We need to use different sensors for different locations in humanoid robotics like fingerprints and belly. Fingerprints of robot are most important part where we need a huge number of sensors on a limited place. As we need a large amount of data for exact modeling of properties contact surface so we require data from a large number of tactile sensors and hence we need to develop an array of tactile sensors.