• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.2
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• pp.30-37
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• 2012

Pneumatic Active Engine Mount(PAEM) with open-loop control system has been developed to reduce the transmission of the idle-shake vibration induced by engine effectively and economically. A solenoid valve installed between PAEM and vacuum tank is on-off switched by the Pulse Width Modulate(PWM) control signal to decrease the dynamic stiffness of the engine mount. This paper presents the methodology to identify the optimal values of control parameters of a PAEM, i.e, turn-on timing and duty ratio of PWM signal for 6 different idle driving conditions. A scanning algorithm was first applied to the vehicle test to obtain the approximate optimal control parameters minimizing the vibration at front seat rail and at steering wheel. Then the PAEM system identification was fulfilled to find accurate optimal control parameters by using multi-layer neural networks of Levenberg-Marquardt algorithm with vehicle test data.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.5
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• pp.389-397
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• 2021

The control characteristics after the failure of the control moment gyros, the actuators for satellite attitude control, were analyzed. In particular, the situation where one out of four failed was considered. For the most commonly used pyramids and box-90 structures, the singularities and singular surfaces after failure were analyzed and compared. Dynamic equations for the process of reducing the wheel speed after the failure were derived. The process of stabilizing the angular velocity of a satellite while absorbing the momentum of the faulty module by the three normal modules was analyzed. For singular shapes, the remaining CMGs may be locked or excessively shake. The authors proposed that it can be prevented by rearranging the gimbal angles.