• Journal of Astronomy and Space Sciences
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• v.16 no.2
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• pp.265-272
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• 1999

A thrusters modulation method is suggested for spacecraft attitude control with asymmetric configured thrusters during orbit adjustment maneuvers. Attitude is controlled by thrusters off-modulation during orbit maneuvers. Usual control method for symmetric configured thrusters cam not be applied for asymmetric configured thrusters. Disturbance induced from thrusters asymmetricity shall be compensated during pulsing. In this paper, a thrusters control method using null solution is suggested, which is shown working well without inducing disturbance.

• Journal of Power System Engineering
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• v.13 no.6
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• pp.129-136
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• 2009

A motor cylinder is widely used as an apparatus for transportation of a small scale load. It is, however, difficult for only one motor cylinder to transfer a large scale load such as a weir. The large scale load is transferred by two motor cylinders which are mounted on right and left of load itself. In this case, the displacement difference generated between two motor cylinders, namely, the synchronous error has a bad influence on the transportation. In this study, a synchronous control system is designed to restrain synchronous error caused by skew disturbance. The control system is composed of two disturbance observers and one synchronous controller. Each disturbance observer is designed to restrain the skew disturbance. And the synchronous controller is designed to achieve stable and accurate synchronization. Finally, the simulation results show that the designed control system is effective for the skew disturbance which lead to synchronous error.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.2
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• pp.349-356
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• 2018

In this study, the synchronous control system is designed to restrain the speed difference generated between two propellers, namely, synchronous error in a dual electric propulsion system of unmanned surface vehicle, fish finder boat, etc. The control system based on coupling structure is composed of pre-filters and speed controllers for each propulsion system and a synchronous controller cross-coupled between two propulsion systems. The pre-filter and speed controller are designed in order that the propulsion system may follow the speed reference without overshoot and input saturation. And the synchronous controller is designed in consideration of damping and quickness of the synchronous controller system after analyzing effect of the skew disturbance and mismatched dynamic characteristics on synchronous error. Finally, the simulation results show that the designed control system is effective for elimination of synchronous error.

• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.57-63
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• 2013

The mission of a lot of satellites on geostationary orbit is the communication and/or the broadcasting. These satellites need a big power, so these have a large solar array. Recently, the new satellite for Earth environment monitoring is developing on geostationary orbit. The payload of Earth monitoring satellite requires better thermal condition on detector. Therefore this satellite uses a boom for the attitude stability instead of rejecting one-side solar array as a heat source. The other hand, it uses some momentum wheels being a more momentum capacity to control the large disturbance by solar pressure due to the asymmetric solar array configuration. In this paper, the analysis on the wheel allocation and the wheel off-loading for COMS is summarized and the results are verified by telemetry of COMS. COMS has no boom and a perfectly asymmetric solar array configuration, and it is operating well on geostationary orbit.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.8
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• pp.706-711
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• 2015

The fighter aircraft uses several different loading configurations for air-to-surface and air-to-air combat missions. To maintain wings-level flight with an asymmetric weapon configuration, a pilot controls a roll trim system. However, it is difficult to apply an accurate roll trim input for wings-level flight in the actual flight under disturbance. The inaccurate roll trim input degrades the performance of the roll autopilot system. In this paper, to solve this problem, an integrator was additionally designed in the command part of the roll autopilot system. The initial transient response was improved by scheduling the limiter to restrict the roll attitude error. As a result of the evaluation of the simulation for the designed flight control law, the roll attitude following performance was found to be improved in the autopilot system operation under the inaccurate roll trim condition.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.5
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• pp.837-844
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• 2017

The weir to regulate water level in a tide generation tank is above and below carried by two electric cylinders which are mounted on right and left of weir itself. In this case, a movement difference between right and left cylinder causes unbalance of weir and friction between weir and guide. And then, the weir will not be sent to target point. In this study, a synchronous control system is developed to take accurate and quick equilibrium of the weir. The control system based on cross coupled structure consists of two I-PD controllers and a lead compensator. Each of the I-PD controllers is designed in order that the electric cylinder may exactly follow the reference signal without overshoot and input saturation. And the lead compensator is designed to achieve stable and accurate synchronization. Finally, the simulation result shows that the designed synchronous control system is effective for elimination of synchronous error.