• Journal of Magnetics
• /
• v.15 no.2
• /
• pp.78-84
• /
• 2010

A 3-D.O.F. spherical PM motor has 3 degrees of freedom in its motion by tilting and rotating of a shaft, which can be applied in a range of fields. The back-EMF is proportional to the field flux and angular velocity. The back-EMF constant in conventional rotating machine has a uniform value. However, in a spherical PM motor, the back-EMF constant of the coils varies according to the tilting conditions regardless of whether the angular speed is constant. Consideration of the back-EMF constant is useful for designing 3-D.O.F. spherical PM motors. In this study, the back-EMF constant of the spherical PM motor was considered carefully.

• Proceedings of the Korea Institute of Convergence Signal Processing
• /
• 2003.06a
• /
• pp.177-182
• /
• 2003

The robust output tracking control problem of general nonlinear MIMO systems is discussed. The robustness against parameter uncertainties is considered. In this paper, we proposed the robust output tracking control scheme for a class of MIMO nonlinear dynamical systems using output feedback linearization method. The presented control scheme is based on the VSS. We assume that the nonlinear dynamical system is minimum phase, the relative degree of the system is r$_{1}$＋r$_{2}$＋…r$_{m}$$\leq$ n and zero dynamics is stable. It is shown that the outputs of the closed-loop system asymptotically track given output trajectories despite the uncertainties while maintaining the boundedness of all signals inside the loop. And we verified that the proposed control scheme is then applied to the control of a two degree of freedom (DOF) robotic manipulator with payload.d.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 1999.11a
• /
• pp.262-266
• /
• 1999

In this paper, we consider to apply of 2-DOF (Degree of Freedom) PID controller at D.C servo motor system. Many control system use I-PD, PID control system, but the position control system have difficulty in controling variable load and changing parameter. We propose neural network 2-DOF PID control system having feature for removal disturbrances and tracking function in the target value point. The back propagation algorithm of neural network used for tuning the 2-DOF parameter ($\alpha$, $\beta$, ${\gamma}$, η). We investigate the 2-DOF PID control system in the position control system and verify the effectiveness of proposal method through the result of computer simulation.

• Earthquakes and Structures
• /
• v.13 no.2
• /
• pp.165-176
• /
• 2017

Multi-Axial Testing System (MATS) is a 6-DOF loading system located at National Center for Research on Earthquake Engineering (NCREE) in Taiwan for advanced seismic testing of structural components or sub-assemblages. MATS was designed and constructed for a large variety of structural testing, especially for the specimens that require to be subjected to vertical and longitudinal loading simultaneously, such as reinforced concrete columns and lead rubber bearings. Functionally, MATS consists of a high strength self-reacting frame, a rigid platen, and a large number of servo-hydraulic actuators. The high strength self-reacting frame is composed of two post-tensioned A-shape reinforced concrete frames interconnected by a steel-and-concrete composite cross beam and a reinforced concrete reacting base. The specimen can be anchored between the top cross beam and the bottom rigid platen within a 5-meter high and 3.25-meter wide clear space. In addition to the longitudinal horizontal actuators that can be installed for various configurations, a total number of 13 servo-hydraulic actuators are connected to the rigid platen. Degree-of-freedom control of the rigid platen can be achieved by driving these actuators commanded by a digital controller. The specification and information of MATS in detail are described in this paper, providing the users with a technical point of view on the design, application, and limitation of MATS. Finally, future potential application employing advanced experimental technology is also presented in this paper.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.12 no.1
• /
• pp.33-38
• /
• 2002

In this paper, a Two-Degree-of-Freedom-Controller(TDFC) for DC motors based on inverse dynamics and the fuzzy technique is presented. The proposed controller includes the inverse dynamic model of a DC motor system, a prefilter and a fuzzy compensator. The model of the system is characterized by a nonlinear equation with coulomb friction. The prefilter eliminates high frequency effects occurring when the inverse dynamic model is implemented. The fuzzy compensator is designed for tracking the change of the reference input and simultaneously regulating the error between the reference input and the system output which can be caused by disturbances. The optimal parameters of both the model and the compensator are identified by a real-coded genetic algorithm. An experimental work on a DC motor system is carried out to verify the performance of the proposed controller.

• 제어로봇시스템학회:학술대회논문집
• /
• 1987.10b
• /
• pp.519-521
• /
• 1987

Among the gyroscopes used for SDINS, the dynamically turned gyroscope (DTG) covers a wide dynamic range while it is simple and small. In addition, it is a two-degree-of freedom gyro; it can detect two-axis input simultaneously. DTG, since its development in 1970's, is widely accepted for strapdown inertial systems. In the first year, we have concentrated on developing a two degree-of-freedom DIG. An interdisciplinary research team has been formed to accomplish the first year objective. Five departments in the College of Engineering, Seoul National University are involved. They are; 1) Department of Control and Instrumentation, 2) Department of Mechanical Design and Production, 3) Department of Electrical Engineering, 4) Department of Electronic Engineering, and 5) Department of Metallurgical Engineering. In addition, the Department of Precision Mechanical Engineering of Pusan National University is subcontracted to develop a test procedure for gyroscope and SDINS. Gyroscope is a key sensor for SDINS. Furthermore gyroscope itself is used as a. independent sensor for vehicle guidance and control and fire control system. Gyroscope and SDINS are an important for defense, aeronautical, and space industries that Korea is and will be actively involved. Upon the success of the project, they are expected to be manufactured in Korea under a cooperative effort between university and industry.

• Journal of the Institute of Electronics Engineers of Korea TE
• /
• v.42 no.4
• /
• pp.47-52
• /
• 2005

In this paper, the genetic algorithm is used to design a fixed order square decoupling $H_{\infty}$ controllers based on the Two-Degree-of-freedom standard model. The proposed decoupling $H_{\infty}$ controller which is minimizes the maximum energy in the output signal is designed to reduce the coupling properties between the input/output variables which make it difficult to control a system efficiently. A minimal set of assumptions for existence of the decoupling controller formula is described in the state-space formulas. It is verified by an example.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10b
• /
• pp.569-572
• /
• 1996

Explicit state-space formulate for an H$_{.inf}$ based two-degrees-of-freedom robust controller are derived in discrete-time. The controller provides robust stability against coprime factor uncertainty, and a degree of robust performance in the sense of making the closed-loop system match a prespecified reference model. It is shown that the controller consists of a plant observer, the chosen reference model, and a generalized state feedback law associated with the plant and model states. The controller structure is shown to be relatively simple and thus may reduce the computational load on the digital control processor.

• Smart Structures and Systems
• /
• v.3 no.1
• /
• pp.115-131
• /
• 2007

The electromechanical integrated toroidal drive is a new drive system. For the control of the drive, the torque fluctuation and the steady-state errors should be removed and the fast response to the input change should be achieved. In this paper, the torque fluctuation of the drive system is analyzed and expressed as Fourier series forms. The transfer function of the torque control for the drive system is derived from its electromechanical coupled dynamic equations. A 2-DOF control method is used to control the drive system. Using definite parameter relationship of the 2-DOF control system, the steady errors of the torque control for the drive system is removed. Influences of the drive parameters on the control system are investigated. Using proper drive parameters, the response time of the control system is reduced and the quick torque response of the drive system is realized. Using a compensated input voltage, the torque fluctuation of the drive system is removed as well. The compensated input voltage can be obtained from the torque fluctuation equation and the transfer function. These research results are useful for designing control system of the new drive.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.41 no.8
• /
• pp.791-797
• /
• 2017

Today, we are using computer simulations in various engineering disciplines to reduce the time and cost of product development. The scope of simulations is increasingly complex and diverse for different fields such as mechanical, electrical, thermal, and fluid. Thus, it is necessary to use integrated simulations. In order to overcome these problems, a language has been developed to effectively describe and implement simulations is Modelica. To model and simulate a system, physical models can be broadly divided into causal and acausal models. The most important feature of Modelica is acausal programming. In this study, we will introduce simple concepts and explain about the usage of Modelica. Furthermore, we will explain the vibration analysis of a two degree-of-freedom system and the design of appropriate parameters by using Modelica.