• 제어로봇시스템학회:학술대회논문집
• /
• 2000.10a
• /
• pp.344-344
• /
• 2000

Recently, the demand for high precision and large stroke in linear positioning systems is increasing in industry. A coarse-fine position control system composed of a linear motor and a piezoelectric actuator has such characteristics. Many optimal control laws have been applied to the position control of coarse-fine actuators but most of them did not take account into constraints. In this study, model predictive control (MPC) method with constraints is applied to the position control of the coarse-fine actuator and the performance of MPC is compared with those of conventional control laws.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2002.04a
• /
• pp.149-154
• /
• 2002

In a high speed spindle system, it is very important to monitor the state of rotating rotor. Particularly in active control spindle system, the position sensor must provide feedback to the control system on the exact position of the rotor. In order to monitor the state of a high speed spindle exactly, high accuracy and wide frequency bandwidth of sensors are important. This paper observes the factors which has an effect on dynamic performances of inductive position sensor.

• Tribology and Lubricants
• /
• v.18 no.1
• /
• pp.49-54
• /
• 2002

In this study, the characteristics of the hydraulic servo mechanism for proportional position control of a hydraulic construction eguipment were analyzed using the developed analysis tool. The result were used in the others hydraulic system except construcdtion eguipment to improve the static performance of the system, the system parameter effects on the controllable region and the hydraulic servo mechanism variation were studied.

• Journal of Mechanical Science and Technology
• /
• v.20 no.7
• /
• pp.993-1001
• /
• 2006

In this paper, a method of accurate position control using a pneumatic cylinder driving apparatus is presented. To overcome the effect of friction force and transmission line, low friction type cylinder applied externally pressurized air bearing structure is used and two control valves attached both side of the cylinder directly. To compensate nonlinear characteristics of control valves, linearized control input derived from the relation between control input and effective area of control valve, and dither signal are applied to the valve. The controller applied to the pneumatic cylinder driving apparatus is composed of a state feedback controller and a disturbance observer. Experimental results show that the effectiveness of the proposed method and position control error of $5{\mu}m$ accuracy could be obtained easily.

• 제어로봇시스템학회:학술대회논문집
• /
• 1987.10b
• /
• pp.340-345
• /
• 1987

This paper is describes the improvement of the transient response of the electrohydraulic position control system which exhibit the over-damped characteristics. A new approach, Position Error Prefiltered Proportional (PEPP) control, is proposed and the computer simulation results for the transient responses are analyzed. Experimental results using Z-80 microprocessor are presented.

• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.2
• /
• pp.35-42
• /
• 2004

The control systems with friction cause the steady state error and slow response, because friction is a sensitive to the change of system condition and has highly nonlinear characteristics. To overcome these problems and do precise position control for a ball-screw system, we use Coulomb friction estimator and the sliding mode control(SMC) to compensate its negative effect. The applied SMC for tracking position has a characteristics of robust stability and reducing chattering, and is derived from the Lyapunov stability theorem and reaching condition. Compensating the estimated friction torque to the bounded disturbance term of the SMC's equivalent control input, it has a tracking performance better than the PID from the experimental results.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10a
• /
• pp.380-384
• /
• 1996

This paper represents an adaptive position controller with the disturbance observer for multi-axis servo system. The overall control system consists of three parts : the position controller, the disturbance observer with free parameters and cross-coupled controller which enhances contouring performance by reducing errors. Using two-degrees-of freedom conception, we design the command input response and the closed loop characteristics independently. The servo system can improve the closed loop characteristics without affecting the command input response. The characteristics of the closed loop system is improved by suppressing disturbance torque effectively with the disturbance observer. Moreover, the cross-coupled controller enhances tracking performance. Thus total position control performance is improved. Finally, the performance of the proposed controller shows that it improves the contouring performance along with the reference trajectory in the XY-table.

• 제어로봇시스템학회:학술대회논문집
• /
• 1987.10b
• /
• pp.364-369
• /
• 1987

It has recently shown that a solenoid valve can be utilized in a hydraulic position-control system by discontinuous control methods. The objective of this study is to investigate the effects of solenoid valves on the response characteristics of a hydraulic position-control system by applying two kinds of discontinued control methods i.e., Simple On-Off (SOF) and Pusating On-Off(POF) controls. Three types of solenoid valves i.e. low-frequency, closed-center type (LF/C), high-frequency, closed-center type (HF/C), low-frequency, tandem-center type(LF/T) were used in this study. Effects of loading conditions and control parameters on the response characteristics were experimentally examined and compared each other. Pressure transients within the actuator were also studied.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.22 no.3
• /
• pp.66-73
• /
• 2008

This paper presents a position sensorless control system of SRM over wide speed range. Due to the doubly salient structure of the SRM, the phase inductance varies along with the rotor position. Most of the sensorless control techniques are based on the fact that the magnetic status of the SRM is a function of the angular rotor position. The rotor position estimation of the SRM is somewhat difficult because of its highly nonlinear magnetizing characteristics. In order to estimate more accurate rotor position over wide speed range, Neural Network is used for this highly nonlinear function approximation. Magnetizing data patterns of the prototype 1-hp SRM are obtained from locked rotor test, and used for the Neural Network training data set. Through measurement of the flux-linkage and phase currents, rotor position is able to estimate from current-flux-rotor position lookup table which is constructed from trained Neural Network. Experimental results for a 1-hp SRM over 16:1 speed range are presented for the verification of the proposed sensorless control algorithm.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.26 no.9
• /
• pp.1795-1805
• /
• 2002

A position controller which can achieve a specified dynamic performance irrespective of the different operating position of the pneumatic cylinder is proposed. The position controller developed in this paper is composed of a nonlinear compensator and a disturbance observer. The nonlinear compensator which feeds back position, velocity and acceleration is derived from the nonlinear dominating equations of the position control system to compensate for variation of dynamic characteristics of a pneumatic cylinder according to the change of the operating position. The disturbance observer including a simplified linear model is designed to reduce the effect of model discrepancy in the low frequency range which cannot be suppressed by the nonlinear compensator. The results of the experiments show that the position control performance maintains a designed performance regardless of the variations of an operating position of the pneumatic cylinder.