• The Transactions of the Korean Institute of Power Electronics
• /
• v.9 no.3
• /
• pp.267-274
• /
• 2004

In this paper, a new on-line dead-time compensation method is proposed. The output voltage errors due to the dead-time effect is considered as disturbance voltages. The magnitude of the disturbance voltages is estimated using a time delay control technique and the disturbance voltages are calculated using the estimated values, measured currents, and position information. The calculated disturbance voltages are fed to voltage references in order to compensate the dead-time effect. The proposed method is applied to a PM synchronous motor drive system and implemented in a digital manner using a digital signal processor (DSP) TMS320C31. The experiments are carried out for this system to show the effectiveness of the proposed method and the results show the validity of the proposed method.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.9 no.3
• /
• pp.253-259
• /
• 2004

This paper presents a speed controller method based on the disturbance torque observer for high-performance speed control of the brushless DC (RLDC) motor. In case of the speed control of robot arms and tracking applications with lower stiffness, we cannot design the speed controller gain to be very large from the viewpoint of the system stability Thus, the feedforward compensation method using disturbance torque observer was proposed. This method can improve the speed characteristic without increasing the speed controller gain. The speed characteristic against disturbance torque can be improved when the bandwidth of the speed controller cannot be made large enough. Consequently, the speed control of the BLDC motor for the high-performance application become achieved.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.15 no.11 s.104
• /
• pp.1303-1310
• /
• 2005

Stabilization error of target aiming systems mounted on moving vehicles is an important performance because the error directly affects hit Probability. In a heavy load targetaiming system, the disturbance torque comes from mass unbalance and linear acceleration is a main source of stabilization error. This study suggests an experimental design method of disturbance feedforward compensation control to improve the stabilization performance of heavy load target aiming systems. The filtered_x least square(FxLMS) algorithm is used to estimate the compensator coefficients adaptively. The proposed control is applied to a simple experimental set-up which simulates dynamic characteristics of a real target aiming system. The feasibility of the proposedtechnique is illustrated, along with results of experiments.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.05a
• /
• pp.488-493
• /
• 2005

In gun stabilization systems, the torque comes from the unbalance mass of gun and the base acceleration is an important source of disturbance which degrades stabilization performance. Fatigue of gear train is another important factor affecting structural safety problems. In this paper, a feedback control gain is designed by optimal control weighting to difference between motor and gun velocity, and a feedforward controller using FXLMS algorithm is adopted to investigate those problems. Experimental results show that the feedforward compensator based on FXLMS can reduce the disturbance effects. The directional convergence property according to initial conditions of the FXLMS is also shown through experiments.

• Journal of Ocean Engineering and Technology
• /
• v.13 no.3B
• /
• pp.91-98
• /
• 1999

In order to reject the steady-state tracking error, it is common to introduce integral compensators in servosystems for constant reference signals. However, if the mathematical model of the plant is exact and no disturbance input exists, the integral compensation is not necessary. From this point of view, a two-degree-of-freedom(2DOF) servosystem has been proposed, in which the integral compensation is effective only when there is a modeling error or a disturbance input. The present paper considers a synthesis problems of this 32DOF servosystem with direct transfer term in the system representation. And, a method how we may obtain a gain such that desirable transient response is achieved, is proposed in the presence of the modelling error and disturbance input.

• Journal of Power System Engineering
• /
• v.3 no.1
• /
• pp.50-54
• /
• 1999

In order to reject the steady-state tracking error, it is common to introduce integral compensators in servosystems for constant reference signals. However, if the mathematical model of the plant is exact and no disturbance input exists, the integral compensation is not necessary. From this point of view, a two-degree-of-freedom(2DOF) servosystem has been proposed, in which integral compensation is effective only when there is modeling error for disturbance input. The present paper considers the design problem of 2DOF servosystem incorporating an observer. It is shown that if a state feedback gain and a observer gain satisfy a condition, the integral effect does not appear when modeling error or disturbance input exists. This result means that the servosystem does not behave as a 2DOF servosystem.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.53 no.8
• /
• pp.500-508
• /
• 2004

This paper presents a new sensorless vector control system for high performance induction motor drives fed by a matrix converter with non-linearity compensation and disturbance observer. The nonlinear voltage distortion that is caused by commutation delay and on-state voltage drop in switching device is corrected by a new matrix converter modeling. The lumped disturbances such as parameter variation and load disturbance of the system are estimated by the radial basis function network (RBFN). An adaptive observer is also employed to bring better responses at the low speed operation. Experimental results are shown to illustrate the performance of the proposed system.

• Journal of Institute of Control, Robotics and Systems
• /
• v.3 no.1
• /
• pp.1-8
• /
• 1997

In order to reject the steady-state tracking error, it is common to introduce integral compensators in servosystems for constant reference signals. However, if the mathematical model of the plant is exact and no disturbance input exists, the integral compensation is not necessary. From this point of view, a two-degree-of-freedom(2DOF) servosystem has been proposed, in which the integral compensation is effective only when there is a modeling error or a disturbance input. The present paper considers robust stability of this 2DOF servosystem incorporating an observer to the structured and unstructured uncertainties of the controlled plant. A robust stability condition is obtained using Riccati inequality, which is written in a linear matrix inequality (LMI) and independent of the gain of the integral compensator. This result impies that if the plant uncertainty is in the allowable set defined by the LMI condition, a high-gain integral compensation can be carried preserving robust stability to accelerate the tracking response.

• Journal of the Korean Society for Precision Engineering
• /
• v.17 no.1
• /
• pp.110-119
• /
• 2000

This paper presents simple and effective nonlinear friction compensation methods. When the direction of position command reverses, the integrator output of the PID controller does not change the sign of its output instantaneously, due to friction at zero velocity, i.e. stiction resulting tracking errors, that results in continuous push even though the command direction has been changed. To overcome this problem, we attempt to reverse the sign of the integrator output as the sign of velocity changes. The effectiveness of this approach is demonstrated by experiments on a 3-PRPS (Prismatic-Revolute-Prismatic-Shperical joints) in-parallel 6-D.O.F manipulator. The control strategy has been analyzed for stability. Also discussed are disturbance observer and velocity observer approaches for friction compensation.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.7
• /
• pp.1289-1294
• /
• 2010

In this paper, a new discrete integral static output feedback variable structure controller based on the a new integral dynamic-type sliding surface and output feedback discrete version of the disturbance observer is suggested for the control of uncertain linear systems. The reaching phase is completely removed by introducing a new proposed integral dynamic-type sliding surface. The output feedback discrete version of disturbance observer is presented for effective compensation of uncertainties and disturbance. A corresponding control with disturbance compensation is selected to guarantee the quasi sliding mode on the predetermined integral dynamic-type sliding surface for guaranteeing the designed output in the integral dynamic-type sliding surface from any initial condition for all the parameter variations and disturbances. Using discrete Lyapunov function, the closed loop stability and the existence condition of the quasi sliding mode is proved. Finally, an illustrative example is presented to show the effectiveness of the algorithm.