• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.1675-1678
• /
• 1997

In this paper, an attitude determination system(ADS) for KOMPSAT using GPS LI carrier phase measurements is considered. The baseline vector is estimated by the Exetnded Kalman Filter (EKF) which used the double differenced carrier phased measuremenmts made by three GPS receivers mounted on the spaceraft. The attitude angles of three axes of spacecrat are computed by the estimated baseline vectors, directly. The proposed ADS is verified by the simulation results.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.1881-1886
• /
• 2005

This paper proposes a novel approach of a precision attitude determination algorithm using UVF (Unit Vector Filter) measurements. The proposed method is superior to the conventional QUEST measurements based approaches because the estimation performance can be greatly enhanced by selecting brighter stars having better noise characteristics. The performance comparison with QUEST measurements is made to verify the usefulness of the proposed algorithm.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.167.5-167
• /
• 2001

Single point attitude determination method provides an optimal attitude minimizing the Wahba loss function. However, for the insufficient number of measurement vectors, the conventional single point methods has no unique solution. Thus, we introduce the sequential method to and an optimal attitude minimizing the windowed loss function. In this paper, this function is de ned as the sum of square errors for all measurement vectors within the axed sliding window. For simple implementation, the proposed algorithm is rewritten as a recursive form. Moreover, the covariance matrix is derived and expressed as a recursive form. Finally, we apply this algorithm to the attitude determination system with three LOS measurement sensors.

• 제어로봇시스템학회:학술대회논문집
• /
• 2000.10a
• /
• pp.5-5
• /
• 2000

Some of Spacecraft's structures are flexible so that a certain expected disturbance can easily excite a low frequency vibration on these structures, having very low natural damping. Such vibration will degrade the performance of the system, which should to be kept in a specific shape or attitude against the undesired vibration, In this paper, LQG/LTR controller is developed using an additional dynamic model to increase the performance of the frequency responses at low frequency area,

• Bulletin of the Korean Space Science Society
• /
• 1995.10a
• /
• pp.28-28
• /
• 1995

No Abstract, See Full Text

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1997.10a
• /
• pp.391-395
• /
• 1997

The transmission of sound and vibration through structures is of interest in many noise control problems, including architectural acoustics, sound transmission through air craft, spacecraft and ship, and the transmission of noise through machinery and engine enclosures. Statistical Energy Analysis provides a simple and accurate method of approaching these problems. In this paper, comparing the measured coupling loss factor of plate-beam with measured coupling loss factor of mass on the junction will be inspected.

• Advances in aircraft and spacecraft science
• /
• v.10 no.1
• /
• pp.1-18
• /
• 2023

This paper investigates the integrated control of an air-breathing hypersonic vehicle considering the safety of propulsion system under acceleration. First, the vehicle/engine coupling model that contains a control-oriented vehicle model and a quasi-one-dimensional dual-mode scramjet model is established. Next, the coupling process of the integrated control system is introduced in detail. Based on the coupling model, the integrated control framework is studied and an integrated control system including acceleration command generator, vehicle attitude control loop and engine multivariable control loop is discussed. Then, the effectiveness and superiority of the integrated control system are verified through the comparison of normal case and limiting case of an air-breathing hypersonic scramjet coupling model. Finally, the main results show that under normal acceleration case and limiting acceleration case, the integrated control system can track the altitude and speed of the vehicle extremely well and adjust the angle deflection of elevator to offset the thrust moment to maintain the attitude stability of the vehicle, while assigning the two-stage fuel equivalent ratio to meet the thrust performance and safety margin of the engine. Meanwhile, the high-acceleration requirement of the air-breathing hypersonic vehicle makes the propulsion system operating closer to the extreme dangerous conditions. The above contents demonstrate that considering the propulsion system safety will make integrated control system more real and meaningful.

• Advances in aircraft and spacecraft science
• /
• v.7 no.5
• /
• pp.459-473
• /
• 2020

The aircraft nose landing gear (NLG) can suffer of an unstable vibration called shimmy that is responsible of discomfort and of fatigue stress on the gear strut components. An adaptive controller is proposed in this paper to cope with the aforementioned problem. It is based on a method called Modified Simple Adaptive control (MSAC) which is able of governing the NLG motion by using a feedback signal that relies on just one output of the plant. The MSAC only asks for the passivity of the controlled plant. With this aim, a parallel feedforward compensator is employed in this work to let the system satisfies the almost strictly passivity (ASP) requirements. The nonlinear equations that govern the aircraft NLG shimmy vibration behavior are used to analyzed the controlled system transient response undergoing an initial disturbance and taking into account different taxiing speed values.

• Journal of computational fluids engineering
• /
• v.12 no.3
• /
• pp.62-68
• /
• 2007

A conceptual thermal design is performed for the optical payload system of a geostationary satellite. The optical payload considered in this paper is GOCI(Geostationary Ocean Color Imager) of COMS of Korea. The radiative thermal control system is employed in order to expect a small thermal gradient in the telescope structure of GOCl. Two design margins are applied to the dedicated radiator dimensioning, and three kinds of configuration to the heater power sizing. A Monte-Carlo ray tracing method and a network analysis method are utilized to calculate radiative couplings and thermal responses respectively. At the level of conceptual design, sizing thresholds are presented for the radiator and heater on the purpose of determining the mass and power budget of the spacecraft.

• Advances in aircraft and spacecraft science
• /
• v.2 no.1
• /
• pp.77-94
• /
• 2015

The paper focuses on the integration of a non-linear one-dimensional model of Synthetic Jet (SJ) actuator in a well-assessed numerical simulation method for turbulent compressible flows. The computational approach is intended to the implementation of a numerical tool suited for flow control simulations with affordable CPU resources. A strong compromise is sought between the use of boundary conditions or zero-dimensional models and the full simulation of the actuator cavity, in view of long-term simulation with multiple synthetic jet actuators. The model is integrated in a multi-domain numerical procedure where the controlled flow field is simulated by a standard CFD method for compressible RANS equations, while flow inside the actuator is reduced to a one-dimensional duct flow with a moving piston. The non-linear matching between the two systems, which ensures conservation of the mass, momentum and energy is explained. The numerical method is successfully tested against three typical test cases: the jet in quiescent air, the SJ in cross flow and the flow control on the NACA0015 airfoil.