• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1996.04a
• /
• pp.341-345
• /
• 1996

Many mechanical and electrocal systems use the number of motors to make multi degree of freedom motion. One method to reduce the number of motors is suggested by using the 3 D.O.F. motor. The 3 D.O.F. motor has advantages such as downsize, weight reduction, and simplification of the existing 3 D.O.F. systems. In this study, a mathematical model for the 3 D.O.F. motor is suggested and the dynamic equation is derived to analyze the 3 D.O.F. motion. Generallinear control methods are very hard to get the good performance because of the nonlinear terms of each degree of each degree of freedom. To control the motion properly, the nonlinear terms are decoupled using a feedback control law. Nonlinear feedback control law which can arrage the poles arbitrarily is derived. The effects of the gains are examined through computer simulations.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1996.04a
• /
• pp.398-402
• /
• 1996

This paper addresses the design and the gait control of quadruped walking robot. First, we concern the mechanical and electronical(control system) hardware of walking robot, and the second is the results of experiments. The walking robot is the most suitable form to substitute fot human being. So walking robot is worthy of research. The quadruped walking robot and control system is the simplest type of walking robot, therefore we designed a small seale robot for realization of static gait. The robot is designed commpactly and its legs are constructed parallel link type and able to move freely in space. Control system consists of one upper level controller and four lower level controllers. The upper level controller plans the walking path and commands the low level controllers to follow the planned path. The main function of low level cotrollers is control of motors. Total number of motors is twealve and they operate four legs. And robot is ordered to walk and realize static wave gait.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.621-625
• /
• 1997

Recently, wash plate type hydraulic axial piston motors are being in extensively used in the world, because of simple design, lightweight, effective cost. But the structural problem of swash plate type hydraulic axial piston motor is the limited angle of swash plate and lateral force having a undesirable effect in piston. To solve these problems. a connecting rod mechanism. which is commonly used in hent axis type motors, is considered to be applied the swash plate cype motor. In this paper, kinematic analysis is done on the connecting rod mechanism. A series of formula are derived and numerical calculations are done for a set of motor parameters.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2006.06a
• /
• pp.77-78
• /
• 2006

A mixed method between $H_2\;and\;H_{\infty}$ control are widely applied to systems which has parameter perturbation and uncertain model to obtain an optimal robust controller. Brushless Direct Current (BLDC) motors are widely used for high performance control applications. Conventional PID controller only provides satisfactory performance for set-point regulation. However, with the presence of nonlinearities, uncertainties and perturbations in the system, conventional PID is not sufficient to achieve an optimal robust controller. This paper presents an approach to ease designing a Mixed $H_2/H_{\infty}$ PID controller for controlling speed of Brushless DC motors and the genetic algorithm is used to solve the optimized problems. Numerical results are shown to prove that the performance in the proposed controller is better than that in the optimal PID controller using LQR approach.

• Journal of Advanced Marine Engineering and Technology
• /
• v.13 no.3
• /
• pp.56-63
• /
• 1989

In recent years, a.c servo motors have been gradually replacing d.c sevo motors in various high-performance demanded aplications such as machine tools and industrial robots. In particular, the high-performance slip-frequency control of an induction motor, which is often called the vector control, is considered one of the best a.c drive. In this paper, the transient state equation and vector control algrithms of an induction motor are described mathematically by using the two-axis theory(d-q coordinates). According to the result of these algorithms, we scheme the speed control system for an induction type ac servo motor in which vector control is adopted to give tha a.c motor high performance. Motor drive is a PWM inverter using power MOS-FET, and is controlled in order to let the actual input current of the motor track the current reference obtained from a microcomputer(8086 cpu). Driving experiments are performed in the range of 0 to 3000 rpm, and it is verified that high speed response is possible.

• Journal of Advanced Marine Engineering and Technology
• /
• v.31 no.1
• /
• pp.95-102
• /
• 2007

The issues of preventive and condition-based maintenance, online monitoring, system fault detection, diagnosis and prognosis are of increasing importance. This study introduces a technique to detect and identify faults in induction motors. Stator currents were measured and stored by time domain. The time domain is not suitable for representing current signals, so wavelet transform is used to convert the signals onto frequency domain. The raw signals can not show the significant feature, therefore difference values between the signal of the health conditions and that of the fault conditions are applied. The difference values were transformed by wavelet transform and the features are extracted from the transformed signals. The dynamic time warping method was used to identify the fault type. This study describes the results of detecting fault using wavelet analysis.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1996.04a
• /
• pp.276-280
• /
• 1996

This paper presents an indirect method for on-line measuring the cutting forces in contour NC milling processes by using the current signals of the servo drive motors. A Kaluman filler is used for estimating each of the load torques to the x, y-axis servo motors of a horizontal machining center. Then, the load torque induced by the friction force in the guidewayis estimated and subtracted from the total extermal torque, thus resulting in the load torque induced by the cutting force. A series of experimental works on the circular interpolated contour milling process shows good agrement between the cutting forces measured by the dynamometer and those estimated by the method presented in the paper.

• 제어로봇시스템학회:학술대회논문집
• /
• 1995.10a
• /
• pp.131-134
• /
• 1995

We developed a visual system that is able to track the moving objects within a certain range of errors. The visual system is driven by two DC servo motors that are controlled by a computer based on the visual data obtained from a CCD video camera. The software to track the moving objects is developed based on the PWM of the DC motors. Also, the problems how to implement a fuzzy logic control method and a neural network in this system, are also considered in order to check the control performance of tracking. The fuzzy logic algorithm is a powerful control technique for nonlinear dynamical system and also the neural network could be implemented in this system. In this paper, we present configuration of tracking system developed in our laboratory, the control methods of the visual system and the experimental results are shown.

• Journal of Institute of Control, Robotics and Systems
• /
• v.5 no.7
• /
• pp.862-867
• /
• 1999

In general, the realization of high performance brushless permanent magnet motors which are widely used in servo drive is focused on the linear control for ripple-free torque. This is also the main problem that should be solved in all AC motors including induction motor to achieve high performance control, and recent papers deal with this problem. In this paper, the novel optimal excitation scheme of brushless permanent magnet motor producing loss-minimized ripple-free torque based on the d-q-0 reference frame is presented including 3 phase unbalanced condition. The optimized phase current waveforms that are obtained by the proposed method can be a reference values and the motor winding currents are forced to track it by delta modulation technique. As a results, it can be shown that the proposed work can minimize the torque ripple by the optimal excitation current for brushless permanent magnet motor with any arbitrary phase back EMF waveform. Simulation and experimental results prove the validity and practical applications of the proposed control scheme.

• Proceedings of the KSR Conference
• /
• 2000.11a
• /
• pp.666-673
• /
• 2000

This paper describes the full load test results of IGBT VVVF inverter for the railway propulsion system. The 1,650kVA IGBT VVVF inverter has been developed. Therefore, the field test is performed in SMG 6 Line to confirm its the reliability and performance. The train consists of 4M4T(4 Motor car 4 Trailer Car) and the electrical equipment for field test are as follows VVVF inverter 4 sets, 16 traction motors and 2 SIVs. The propulsion system is composed with IC4M(1-Controller 4-Motors). The results of propulsion system which have the excellent acceleration/deceleration and the jerk characteristics as well as starting ability on slope are taken through the field test.