• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.35.3-36
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• 2008

The ground-based spacecraft simulator is a useful tool to realize various space missions and satellite formation flying in the future. Also, the spacecraft simulator can be used to develop and verify new control laws required by modern spacecraft applications. In this research, therefore, Hardware-in-the-loop (HIL) simulator which can be demonstrated the experimental validation of the theoretical results is designed and developed. The main components of the HIL simulator which we focused on are the thruster system to attitude control and automatic mass-balancing for elimination of gravity torques. To control the attitude of the spacecraft simulator, 8 thrusters which using the cold gas (N2) are aligned with roll, pitch and yaw axis. Also Linear actuators are applied to the HIL simulator for automatic mass balancing system to compensate for the center of mass offset from the center of rotation. Addition to the thruster control system and Linear actuators, the HIL simulator for spacecraft attitude control includes an embedded computer (Onboard PC) for simulator system control, Host PC for simulator health monitoring, command and post analysis, wireless adapter for wireless network, rate gyro sensor to measure 3-axis attitude of the simulator, inclinometer to measure horizontality and battery sets to independently supply power only for the simulator. Finally, we present some experimental results from the application of the controller on the spacecraft simulator.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.173.3-173
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• 2001

In this paper, attitude control of autonomous system using bike based on variable structure control is discussed. Variable structure control is more than a promising technique in the field of nonlinear control. It permits the realization of very robust and simple regulators, with appealing sliding mode characteristics especially if the considered dynamics requires a very short sampling time. We derive dynamic equation of it and demonstrate that the designed controller stabilizes attitude simultaneously regardless of wheel position by computer simulation.

• Transactions on Control, Automation and Systems Engineering
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• v.3 no.4
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• pp.257-261
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• 2001

Nonlinear pulse width modulation (PWM) controlled system is considered to achieve control performance of thruster controlled spacecraft. The actual PWM controlled motions occur, very closely, around the average model trajectory. Furthermore nonlinear PWM controller design can be directly applied to thruster controlled spacecraft to determine thruster on-time. Sliding mode control for attitude tracking of three-axis thruster-controlled spacecraft is presented. Simulation results are shown which use modified Rodrigues parameters and sliding mode control law to achieve attitude tracking of a three-axis spacecraft with thrusters.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.8
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• pp.688-693
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• 2013

This paper proposes a new method on attitude control of an underwater robot by using five ABTs (Attitude Ballast Tank). A pipe is connected to the bottom of the ABTs and transfers water by a pump, while another pipe is connected to the top of the ABT to transfer air. The buoyancy center of the underwater robot can be changed by means of the water transfer. This way, the attitude of the underwater robot can be maintained and/or controlled as desired. The changes of the center of gravity and the buoyancy central are estimated by a Lagrangian function which is similar to that for an inverted pendulum. The controller in this paper is designed by modeling of the underwater robot and selecting suitable gains of a PD controller which has fast response characteristics. This paper shows the possibility of the attitude control of an underwater robot by changing the center of gravity and the buoyancy center of the robot. Moreover, experimental results verify that the controller is effective in maintaining Roll/Pitch of the underwater robot with very low power consumption.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.7
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• pp.556-562
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• 2003

This paper presents new attitude error differential equations to define attitude errors as the rotation vector for inertial navigation systems. Attitude errors are defined with the rotation vector between the reference coordinate frame and the platform coordinate frame, and Platform dynamics to the reference coordinate frame due to platform torque command errors are defined. Using these concepts for attitude error definition and platform dynamics, we have derived attitude error differential equations expressed in original nonlinear form for GINS and SDINS and showed that these are equivalent to attitude error differential equations expressed in known linear form. The relation between attitude errors defined by the rotation vector and attitude errors defined by quaternion is clearly presented as well.

• Journal of Advanced Navigation Technology
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• v.16 no.1
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• pp.1-7
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• 2012

In this research, a single-axis attitude control test bed is developed, and simulation and tests experiments are performed, as a preliminary research of a quad-rotor aerial vehicle development. A single-axis test bed with seesaw configuration is manufactured using two motors and propellers, and the aerodynamic parameters are derived by thrust tests. The response of the system is estimated with Matlab/Simulink, and experiments are performed with attitude control computer and an attitude sensor onboard the test bed. Comparing the results of simulated and tested data, factors of steady-state errors during experiments are found, and performances of used attitude control algorithm and the control computer were verified. In these process, essential preliminary data for attitude control of a quad-rotor unmanned aerial vehicle were acquired.

• Journal of Digital Convergence
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• v.19 no.8
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• pp.49-57
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• 2021

This paper aims to confirm the effect of self-control and organization-control on information security attitude. The research method is composed of a cross-design of locus of control and tightness culture. The measurement variables used in the assessment are information security actual attitude, compliace behavioral attitude, and information security efficacy. As a result, the locus of control had a significant effect on information security actual attitude, information security efficacy, information security efficacy, and it was found that influence of the internal-based condition was greater than the external-based condition. The tightness culture had a significant effect on compliace behavioral attitude, information security efficacy, and it was found that influence of the tight culture-based condition was greater than the loose culture-based condition. In addition, the discussion contatins the implications of information security direction that reflect these research results.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.11
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• pp.1104-1109
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• 2010

This paper deals with the attitude control of an underactuated spacecraft that has fewer than three actuators. Even though such spacecrafts are known as uncontrollable, restricted missions are possible with controlling two-axis attitude angles. A variable speed control moment gyroscope is considered as an actuator. It is a kind of momentum exchange device and it shows highly nonlinear dynamical properties. Speed commands are generated by kinematic equations represented by Euler angles. A control law, that is designed to make a spacecraft follow the speed commands, is derived by the backstepping method. Angular speeds are estimated from the attitude measurements. Several estimation methods have been compared.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.4
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• pp.675-684
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• 2004

The Helicopter system has a non-linearity and complexity. Futhermore, because of absence of its correct mathematical model. it is difficult to control accurately its attitudes for elevation angle and azimuth one. Therefore, we proposed a GA-PID control technique to control these angles efficiently. The proposed GA-PID controller can systematically generate optimal PID parameters by applying GA theory to a helicopter attitude control system. Through the computer simulation, the GA-PID technique shows better attitude control characteristic than traditional PID control technique.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.563-565
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• 1999

In this paper, we control attitude of an unstructured object with gyro actuator. It is well known that the attitude control of an object hanging with wire is not easy using usual actuators. Even though an actuator such as a fan can be used for control of the object, it is difficult to meet a desired control objectives. We, because of these reasons, make a gyro actuator with two motors. The first motor is responsible for spinning the wheel at high speed and the second motor is used to turn the inner gimbal. Applying the torque to the second motor, which results in the turn of the outer gimbal, torque about the vertical axis will be obtained while the wheel of the gyro is spinning constantly. This torque is used to control the attitude of the object attached. Gyro actuator utilize control unstructured object such as I-beam carrying by tower crane, and isolate construction workers from the dangerous environments. We derive a relationship of wheel and its motor, find a proper capacity of wheel motor in order to rotate a wheel. Through experiments of attitude control, we show to obtain desired control objectives.