• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.3
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• pp.388-395
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• 2009

Surveillance Radar System for naval vessels is a primary core sensor for command and fire control, and provides CFCS(Command and Fire Control System) information for 3-D surveillance and fire control. It's composed of Antenna, Transmitter/Receiver, Signal Processor, and Air drier, which are installed on and under deck. They should be designed and produced in order to endure at any operating circumstances. This paper analyzes load of a driving part for driving the antenna considering factors under external operating circumstances, and proposes a condition of load for maintaining fixed RPM through analyzing internal load of the driving part, and how to reduce the load to meet the condition. This paper is verified through experimental studies.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.910-914
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• 2005

In this paper an optimal method based on fuzzy logic for controlling parallel hybrid electric vehicles is presented. In parallel hybrid electric vehicles the required torque for deriving and operating the on-board accessories is generated by a combination of internal-combustion engine and an electric motor. The powersharing between the internal combustion engine and the electric motor is the key point for efficient driving. This is a highly nonlinear and time varying plant and its control strategy will be implemented with the use of fuzzy logic controller. The fuzzy logic controller will be designed based on the state of charge of batteries and the desired torque for driving. The output of controller controls the throttle of the combustion engine. The main contribution of this paper is the development of an optimal control based on fuzzy logic, which maximizes the output torque of the vehicle while minimizing fuel consumed by the combustion engine.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1424-1429
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• 2004

In this paper a mathematical framework for deriving acceleration bounds from given joint torque limits of multiple cooperating robots are described. Especially when the different frictional contacts for every contact are assumed and the torque limits are given in 2-norm sense, we show that the resultant geometrical configuration for the acceleration is composed of corresponding parts of ellipsoids. Since the frictional forces at the contacts are proportional to the normal squeezing forces, the key points of the work includes how to determine internal forces exerted by each robot in order not to cause slip at the contacts while the object is carried by external forces. A set of examples composed of two robot systems are shown with point-contact-with-friction model and insufficient or proper degree of freedom robots.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2717-2720
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• 2003

A mathematical framework for deriving acceleration bounds from given joint torque limits of two cooperating robots are described in this paper. Especially when the torque limits are given in 2-norm, the resultant geometrical configuration is ellipsoid(the ellipsoid is often called manipulability ellipsoid in many works). At first, the mathematical derivation starts from the dynamics of both object and robots as well as the kinematics of the robots, and is finally arranged in a form of equation relating joint torques to object acceleration through a complete constraint contact(or “very-soft contact”). To show the usefulness of the proposed method, two examples are included, and especially the case where friction effects the ellipsoid shape is also considered In the example.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.10
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• pp.887-898
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• 2004

In this paper a mathematical framework fur deriving acceleration bounds from given joint torque limits of multiple cooperating robots are described. Especially when the different frictional contacts for every contact are assumed and the torque limits are given in 2-norm sense, we show that the resultant geometrical configuration for the acceleration is composed of corresponding parts of ellipsoids. Since the frictional forces at the contacts are proportional to the normal squeezing forces, the key points of the work includes how to determine internal forces exerted by each robot in order not to cause slip at the contacts while the object is carried by external forces. A set of examples composed of two robot systems are shown with point-contact-with-friction model and insufficient or proper degree of freedom robots.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.490-492
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• 1998

An intention of this paper is design of a gyro actuator for the attitude control of an unstructured object. 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 pan can be used for control of the object, it is difficult to meet a desired control objectives. We, for this reason, propose a gyro actuator for the attitude control of an unstructured object. The proposed gyro actuator consists of two motors. The first motor is responsible to spin the wheel and the second motor is used to turn the outer gimbal. Appling the torque to the second motor, which results in the turn of the outer gimbal, torque about the vertical axis will be obtained while a wheel of the gyro is spinning constantly. This torque is used to control the attitude of the object attached. The aim of this paper is of deriving the transfer function of the actuator and presenting the guideline of the design parameters such as the weight and the dimension of the wheel, motors, and the load capacity. Simulations to the mathematical model which has a state feedback control are conducted to show the validity of the proposed gyro actuator.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.10
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• pp.1006-1013
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• 2011

In this paper, we propose an optimal posture control law for an unmanned bicycle by deriving linear bicycle model from fully nonlinear differential equations. We calculate each equilibrium point of a bicycle under any given turning radius and angular speed of rear wheel. There is only one equilibrium point when a bicycle goes straight, while there are a lot of equilibrium points in case of turning. We present an optimal equilibrium point which makes the leaning input minimum when a bicycle is turning. As human riders give rolling torque by moving center of gravity of a body, many previous studies use a movable mass to move center of gravity like humans do. Instead we propose a propeller as a new leaning input which generates rolling torque. The propeller thrust input makes bicycle model simpler and removes input magnitude constraint unlike a movable mass. The proposed controller can hold optimal equilibrium points using both steering input and leaning input. The simulation results on linear control for circular motion are demonstrated to show the validity of the proposed approach.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.4
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• pp.241-250
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• 2022

This paper addresses the Feasible Angular Momentum(FAM) chart that can be used as an indicator for maneuverability analysis of spacecraft installed with control moment gyros(CMGs). Recently, as the demands for high agility of spacecraft has been increasing in order to perform the space mission given to spacecraft more effectively, interest in CMGs, which is a high torque generator is increasing. However, since the CMG has a singularity problem that does not generate the control torque in the specific directions, in this paper, we consider the two pairs of parallel control moment gyros(TPCMGs) that follows the roof-type configuration. The Gimbal space was newly defined except for the space where singularity can be generated and the space where torque error is generated due to the hardware limits. The feasible angular momentum space is defined as a FAM chart, and it is very meaningful that it is possible to analyze the spacecraft's rotational maneuverability effectively by deriving the spacecraft's 3-axis parameters in the corresponding gimbal space mathematically.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.134-137
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• 2001

In this paper on-line model is derived from investigating via series of finite element process simulation. Some variables that little affect on non-dimensional parameters. ie. forward slip and torque factor. is extracted from composing on-line model Especially, this research focused on deriving on-line model which exactly predict roll force and roll power in the roughing mill process under small shape factor and small reduction ratio. The prediction accuracy of the proposed model is examined through comparison with predictions from a finite element process model

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.2
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• pp.270-277
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• 2013

Single phase induction motor(SPIM) is used widely because it is driven by single phase source. However, the efficiency of the motor is not good due to saturation of magnetic material. To analyze the motor accurately, the magnetic saturation characteristics should be considered in analysis of equivalent circuit. In this paper, lumped parameter of circuit are derived from multi phase induction motor using method of symmetrical coordinates. Also, we presents a method for the equivalent circuit analysis of SPIM using magnetic saturation rate. The magnetic nonlinearity is considered deriving magnetizing reactance from voltage-current saturation curve. As a results, current characteristic, torque, output and efficiency are shown through analysis of equivalent circuit. A simulation results of SPIM will be used to improve the characteristics and efficiency of motor.