• International Journal of Aeronautical and Space Sciences
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• v.15 no.1
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• pp.82-90
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• 2014

In this paper, the effect of Lorentz force on the stability of attitude orientation of a charged spacecraft moving in an elliptic orbit in the geomagnetic field is considered. Euler equations are used to derive the equations of attitude motion of a charged spacecraft. The equilibrium positions and its stability are investigated separately in the pitch, roll and yaw directions. In each direction, we use the Lorentz force to identify an attitude stabilization parameter. The analytical methods confirm that we can use the Lorentz force as a stabilization method. The charge-to-mass ratio is the main key of control, in addition to the components of the radius vector of the charged center of the spacecraft, relative to the center of mass of the spacecraft. The numerical results determine stable and unstable equilibrium positions. Therefore, in order to generate optimum charge, which may stabilize the attitude motion of a spacecraft, the amount of charge on the surface of spacecraft will need to be monitored for passive control.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.8
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• pp.758-765
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• 2015

This paper proposes an attitude control system to keep the balance for a two-wheeled mobile manipulator which consists of a mobile platform and a three D.O.F. manipulator. In the conventional control scheme, complicated dynamics of the manipulator need to be derived for balancing control of a mobile manipulator. The method proposed in this paper, however, three links are considered as one body of mass and the dynamics are derived easily by using an inverted pendulum model. One of the best advantage of a sliding mode controller is low sensitivity to plant parameter variations and disturbances, which eliminates the necessity of exact modeling to control the system. Therefore the sliding mode control algorithm has been adopted in this research for the attitude control of mobile platform along the pitch axis. The center of gravity for the whole mobile manipulator is changing depending on the motion of the manipulator. And the orientation variation of center of gravity is used as reference input for the sliding mode controller of the pitch axis to maintain the center of gravity in the middle of robot to keep the balance for the robot. To confirm the performance of controller, MATLAB Simulink has been used and the resulting algorithms are applied to a real robot to demonstrate the superiority of the proposed attitude control.

• International Journal of Computer Science & Network Security
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• v.23 no.7
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• pp.79-90
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• 2023

Leadership development corresponds to the focus on the individual's success and competitiveness strategy. This is the optimal direction of the organization of attitude development because it covers two aspects of the student's personality development, professionally-oriented and self-centric. The aim of the study is to identify and compare the leadership level in second-and fourth-year students to see dynamics of development and implementation of the leadership phenomenon in the professional and personal making up of future specialists. Based on the theoretical analysis of the issue, the authors developed an objective and subjective diagnostic model for leadership skills. In this study, data of the objective diagnostic technique are the key. Subjective diagnostic technique for leadership skills provides insights for problem interpretation. At the level of the first group of respondents, the average Leadership Skills Level of the second-year students was quite low and was found within the medium level. The second group of respondents consisting of the fourth-year students showed a slight but effective improvement. The Leadership Skills of this group were found at a sufficient level. Positive dynamics was revealed for all criteria of leadership skills as a result of applying objective diagnostic methods: decreased percentage of students with negative and relatively low markers of Leadership Skills Level and corresponding increase in percentage of applicants with positive markers of Leadership Skills Level. Further research can be organized in the direction of identifying and developing successful universal and professionally-oriented tactics for leadership development in students as part of attitude development.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.2
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• pp.222-231
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• 2016

This paper proposes a new method achieving computationally efficient attitude reference system for low cost strapdown sensors and microprocessor platform. The main idea in this method is to define and compare velocity differential vectors, geometrically computed from INS and GPS data with different update rate, for generating attitude error measurements which is further used for filter construction. A quaternion based Kalman filter configuration is applied for the attitude estimation with the adapted measurement model of differential vector comparison. Linearized model for Extended Kalman Filter and low pass filtered characteristics of measurement greatly extend the affordability of the proposed algorithm to the field of simple low cost embedded systems. For performance verification, experiment are done employing a practical low cost MEMS IMU and GPS receiver specification. Performance comparison with a high grade navigation system demonstrated good estimation result.

• International Journal of Aeronautical and Space Sciences
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• v.8 no.2
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• pp.89-97
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• 2007

COMS(Communication, Oceanography, and Meteorology Satellite) is the first Korean multi-purpose satellite which is planned to be deployed at the altitude of geosynchronous orbit above the Korean peninsular. Noting that COMS is composed of the main BUS structure, two deployable solar panels, one yoke, five reactions wheels, COMS is treated as a collection of 9 bodies and its nonlinear equations of motion are obtained using the multi-body dynamics approach. Also, a computer program is developed to analyze the COMS motion during the various mission phase. Quite often, the equations of motion have to be derived repeatedly to reflect the fact that the spacecraft dynamics change as its configuration, and therefore its degree of freedom varies. However, the equations of motion and simulation software presented in this paper are general enough to represent the COMS dynamics of various configurations with a minimum change in input files. There is no need to derive the equations of motion repeatedly. To show the capability of the simulation program, the spacecraft motion during the solar array partial and full deployment has been simulated and the results are summarized in this paper.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.1
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• pp.54-63
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• 2016

A novel attitude tacking control method using Time Delay Control (TDC) scheme is developed to provide robust controllability of a rigid hexacopter in case of single or multiple rotor faults. When the TDC scheme is developed, the rotor faults such as the abrupt and/or incipient rotor faults are considered as model uncertainties. The kinematics, modeling of rigid dynamics of hexacopter, and design of stability and controllability augmentation system (SCAS) are addressed rigorously in this paper. In order to compare the developed control scheme to a conventional control method, a nonlinear numerical simulation has been performed and the attitude tracking performance has been compared between the two methods considering the single and multiple rotor faults cases. The developed control scheme shows superior stability and robust controllability of a hexacopter that is subjected to one or multiple rotor faults and external disturbance, i.e., wind shear, gust, and turbulence.

• Journal of Astronomy and Space Sciences
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• v.19 no.2
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• pp.107-122
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• 2002

Multi-body spacecraft attitude and configuration control formulations based on the use of collaborative control theory are considered. The control formulations are based on two-player, nonzero-sum, differential game theory applied using a Nash strategy. It is desired that the control laws allow different components of the multi-body system to perform different tasks. For example, it may be desired that one body points toward a fixed star while another body in the system slews to track another satellite. Although similar to the linear quadratic regulator formulation, the collaborative control formulation contains a number of additional design parameters because the problem is formulated as two control problems coupled together. The use of the freedom of the partitioning of the total problem into two coupled control problems and the selection of the elements of the cross-coupling matrices are specific problems ad-dressed in this paper. Examples are used to show that significant improvement in performance, as measured by realistic criteria, of collaborative control over conventional linear quadratic regulator control can be achieved by using proposed design guidelines.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.377-382
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• 2005

This paper presents a new method for the attitude control of planar space robots. In order to control highly constrained non-linear system such as a 3D space robot, the analytical formulation for the system with complex dynamics and effective control methodology based on the formulation, are not always obtainable. In the proposed method, correspondingly, a non-analytical but effective self-organizing modeling method for controlling a highly constrained system is proposed based on a polynomial data mining algorithm. In order to control the attitude of a planar space robot, it is well known to require inputs characterized by a special pattern in time series with a non-deterministic length. In order to correspond to this type of control paradigm, we adopt the Model Predictive Control (MPC) scheme where the length of the non-deterministic horizon is determined based on implementation cost and control performance. The optimal solution to finding the size of the input pattern is found by a solving two-stage programming problem.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.10
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• pp.956-960
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• 2004

The Vehicle Dynamic Simulator(VDS) is a key equipment of the performance verification of attitude control subsystem and it simulates the real dynamic environment that spacecraft undergoes during mission operation. All the software models and hardware interfaces necessary for the closed-loop simulation of the spacecraft dynamics are implemented. Using VDS, KOMPAT-2 attitude control logic functions and performance was verified. In this paper, the hardware and software configurations of KOMPSAT-2 VDS was described briefly and the information flow and exchanges between software models and actual hardwares during close loop simulation was described in the systematic point of view.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.3
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• pp.285-294
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• 2015

As a "kind of" mature ship form, planing hull has been widely used in military and civilian areas. Therefore, a reasonable design for planing hull becomes more and more important. For planing hull, resistance and trim are always the most important problems we are concerned with. It affects the planing hull's economic efficiency and maneuverability very seriously. Instead of the expensive towing tank experiments, the development of computer comprehensive ability allows us to previously apply computational fluid dynamics(CFD)to the ship design. In this paper, the CFD method and Goal Driven Optimization (GDO) were used in the estimations of planing hull resistance and running attitude to provide a possible method for performance computation of planing hull.