• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.41 no.2
• /
• pp.107-119
• /
• 2013

We study three axis attitude control method including two axis high agile maneuver using four reaction wheels and two control moment gyros. We investigate singularity conditions due to two control moment gyros and propose singularity escape method. Based on this, we propose actuator control algorithm for high agile maneuver. Also, we propose actuator momentum management method which preserves momentum of reaction wheels and control moment gyroscopes before and after satellite attitude control. Through numerical simulation, we show that our method achieves three axis attitude control including two axis high agile maneuver and preserves actuators' momentum.

• Journal of Auto-vehicle Safety Association
• /
• v.5 no.1
• /
• pp.37-43
• /
• 2013

This paper describes an investigation into coordinated control of electronic stability control (ESC) and active roll control system (ARS). The coordinated control is suggested to improve the vehicle stability and agility features by yaw rate control. The proposed integrated chassis control algorithm consists of a supervisor, control algorithms, and a coordinator. The supervisor monitors the vehicle status and determines desired vehicle motions such as a desired yaw rate and desired roll motion based on control modes to improve vehicle stability. According to the corresponding the desired vehicle dynamics, the control algorithm calculated a desired yaw moment and desired roll moment, respectively. Based on the desired yaw moment and the desired roll moment, the coordinator determines the brake pressures and the ARC motor torques based on control strategies. Closed loop simulations with a driver-vehicle-controller system were conducted to investigate the performance of the proposed control strategy using CarSim vehicle dynamics software and the integrated controller coded using Matlab/Simulink.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.7 no.7
• /
• pp.221-228
• /
• 1999

A full-time four wheel drive vehicle is driven literally full time by the front and the rear wheels. Front and rear drive shafts are rotated rapidly in the extremely torsional state, which can cause various vibration and noise problems. The purpose of this study is to reduce the vibration and the noise of the full -time four wheel drive vehicle. In this paper, both the causes and the methods for reduction of torsional vibration are suggested. For this study, the characteristics of the torsional vibration are analyzed by free and forced torsional vibration simulation. And this paper described the influence upon the torsional vibration with emphasis shafting system. The validity of simulation models is checked by the field test. The forced vibration simulation with the variations of shaft design factors are performed by the checked models. According to the simulation , the resonance region shifts and the torque fluctuation varies in the system,. Finally, the methods and the effects for the torsional vibration reduction in driveline are proposed.

• 한국초전도학회:학술대회논문집
• /
• v.9
• /
• pp.310-314
• /
• 1999

A prototype of Flywheel Energy Storage System with high Tc superconducting bearings was fabricated and tested to verify its applicability for the energy industry. The moment of inertia of assembled wheel with rotor magnets is about 1.072${\times}$10$^{-1}$ Kg-m$^2$. The wheel was designed to withstand its integrity up to the rotation speed of 20,000 rpm. YBCO bulk superconductors prepared by seed growth method were used as bearing to levitate and stabilize the rotating wheel. High speed rotation of the flywheel without mechanical contact was achieved by using specially designed Halbach type motor. The flywheel system showed very high stability during test operation performed up to the speed of about 10,000rpm. The energy loss measured by free decay test performed between 9,300 rpm and 7,000 rpm was calculated as about 45 W.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.49 no.8
• /
• pp.459-466
• /
• 2000

In this paper, we propose an attitude controller for an unstructured object using CMG(Control Moment of Gyro) subsystem, which has a stabilizer function. The CMG subsystem consists of one motor for spinning the wheel and the other motor for turning the outer gimbal. While the wheel of CMG subsystem is spinning at high speed, applying force to the spin axis of the wheel leads the torque about the vertical axis. We utilize the torque to control the attitude of object in this study. For the stabilizer function, in additiion, holding the load at the current position, the power applied to the gimbal motor of CMG will be cut, which result in the braking force to stop the load by gyro effect. However, due to the gear reduction connected to outer gimbal, slow load motion cannot generate the braking force. Thus, in this study, we are willing to make a holding force by applying control power to the gimbal motor from the signal of piezoelectric gyroscopic sensor that detected the angular velocity of the load. These two features are demonstrated in experiment, carrying a beam with crane. As a result, load was started to rotate by controlling gimbal positiion and was stopped by turning off the gimbal power. Moreover, slow movement of the load was also rejected by additional control with gyroscopic sensor.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.22 no.3
• /
• pp.244-252
• /
• 2012

Recently, the speed of a train has been increased. So the trains are being exposed to wind more severely than before. Because of the operation of high speed trains and lightweight of the train, risks of train derailment have being increased. In this study, aerodynamic effects of a newly designed high speed train, HEMU-400x, are evaluated. For aerodynamic effect evaluation, analysis method is selected by examining the safety standards for high speed train. The condition of aerodynamic effects is selected by adverse effect conditions. In order to calculate $C_s$ coefficients, numerical analysis is conducted. Using $C_s$ coefficients, the side force is calculated. Through dynamics analysis, derailment and wheel unloading are obtained. Using these results, derailment evaluation is performed.

• Journal of Institute of Control, Robotics and Systems
• /
• v.21 no.11
• /
• pp.1064-1069
• /
• 2015

Control Moment Gyro (CMG) has been used as an indirect actuator of a single-wheel robot system GYROBO, developed at Chungnam National University. The flip motion of the gimbal system produces the gyroscopic motion onto the body system while the body motion also produces the gyroscopic motion onto the gimbal system inversely. In this paper, the intuitive equation of the inverse gyroscopic effect is derived as the direct relation between the rate of the body system and the rate of the gimbal system. Experiments on the inverse gyroscopic effect under the chaotically generated disturbance are conducted. Experimental data are approximated by a linear equation using the least square method.

• Proceedings of the KIPE Conference
• /
• 2013.11a
• /
• pp.69-70
• /
• 2013

By using differential force between left and right wheel, lateral motion can be controlled known as Direct Yaw-moment Control (DYC). In previous researches, DYC control is proposed to increase the stability of the vehicle, but maneuverability has not been discussed sufficiently. The car handling condition which is called the index parameter of maneuverability is dependent on the vehicle velocity and steering angle. To achieve the desired vehicle's cornering path, the car handling condition must be considered sufficiently. In this paper, the novel DYC method is proposed which gives the car handling condition regardless of the longitudinal speed. The proposed controller is based on the PI controller to feedback the curvature parameter. The controlled system shows the advantages of DYC regarding to the reference trajectory by the dual motor system. With respect to the uncontrolled model, the effectiveness of the proposed method is validated by numerical examples.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.6 no.2
• /
• pp.1-11
• /
• 1998

The 4WS system is usually developed to improve the maneuverability at low speed and the straight line stability at high speed, but it is found to have the severe understeer characteristics at high speed. Therefore a 4WS vehicle requires to turn the steering wheel much more than a 2WS vehicle at high speeds even a driver goes through the same curved road. In this study, to enhance the cornering performance of the 4WS vehicle at high speed, a DYC 4WS system is proposed based on the nonlinear 4WS system and direct yaw moment control system. Especially the proposed DYC 4WS system is able to realize a zero side slip angle for vehicles and a cornering performance similar to the 2WS vehicle at high speed.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.8 no.5
• /
• pp.165-172
• /
• 2000

The VDC(Vehicle Dynamic Control) is a control system whose target is to improve stability of a vehicle under lateral motion. A lateral vehicle motion, especially on a slippery road, can lead to a hazardous situation, and the situation can even worsen by the driver`s inappropriate response. In this paper, two VDC systems, a fuzzy-based controller and an LQR-based controller have been developed. The controllers take as input the yaw rate and the sideslip angle of either body or rear wheel, and they yield the direct yaw moment signal by which the vehicle can gain stability during cornering. Simulations have been conducted to evaluate the performance of the control system. The results indicated that the controllers can successfully improve vehicle stability under potentially dangerous driving conditions.