• Journal of the Institute of Convergence Signal Processing
• /
• v.4 no.3
• /
• pp.49-54
• /
• 2003

In this paper, we propose a controller with the self-organizing neural network compensator for compensating PID controller's response. PID controller has simple design method but needs a lot of trials and errors to determine coefficients. A neural network control method does not have optimal structure as the parameters are pre-specified by designers. In this paper, to solve this problem, we use a self-organizing neural network which has Back Propagation Network algorithm using a Gaussian Potential Function as an activation function of hidden layer nodes for compensating PID controller's output. Self-Organizing Neural Network's learning is proceeded by Gaussian Function's Mean, Variance and number which are automatically adjusted. As the results of simulation through the second order plant, we confirmed that the proposed controller get a good response compare with a PID controller. And we implemented the of controller performance hydraulic servo motor system using the DSP processor. Then we observed an experimental results.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.3
• /
• pp.74-80
• /
• 2006

This paper deals with the control and fault monitoring of a DDV hydraulic actuation system. A hydraulic servo system has a nonlinear dynamics of an orifice flow through a valve spool. A full nonlinear model for a DDV actuation system is driven, and linearized to a simple model which is convenient for a control loop and fault monitor design. A top level requirement on the performance and safety for the actuation system is introduced. A control system and fault monitoring structure which can meet these requirements are discussed. A simulation package for a DDV actuation system which has a triplex redundant structure is developed.

• Journal of Institute of Control, Robotics and Systems
• /
• v.14 no.5
• /
• pp.462-466
• /
• 2008

This paper proposes a stable gain scheduling method of linear time invariant controllers for tracking servo system. In order to read and write the data on the optical disc, the pick-up head should be moved to the exact track quickly and follow the track immediately. Two different controllers are used for each moving and track-following. In pull-in period, a transition period from moving to track-following, the head might slip and miss the target track. This brings on another searching process and increases the total time. One way to avoid slipping is to extend the bandwidth of the track-following controller. But, extending the bandwidth could degrade the following performance. More prevalent way is to use one more controller in this pull-in period and switch to the following controller. In general, however, switching or scheduling of stable controllers cannot guarantee the stability. This paper suggests an scheduling method guaranteeing the overall stability not only in a generalized form but also in special form for SISO system. The sufficient condition is derived from the fact that Q factor of a stable controller should be stay in $RH_{\infty}$ space. In the experiment, the proposed method shows better performance than the switching method such as shorter time and lower current consumption.

• Proceedings of the KIEE Conference
• /
• 1996.07a
• /
• pp.124-126
• /
• 1996

In this paper, the driving systems of the Fiber Optic Gyrocompass absolutely required a constant speed and a precise position control with fine step angle, are presented. One of the proposed systems is a stepping motor system with microstep driver, another one is a DC servo motor. Experimental results indicate that a low cost and simple FOG driving system using a stepping motor is capable of a satisfactory operation.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.34 no.3
• /
• pp.35-40
• /
• 2011

5-axis laser cutting has great advantages when it is applied to three dimensional machining requiring high cutting quality. For developing 5-axis CNC laser cutting systems, however, many problems such as rotating a laser head or a working table, 5-axis servo-control mechanism, tool path generation and post-processing, and collision avoidance between a laser head and a work-piece should be solved. In this paper, we deal with developing a motion simulator for 5-axis laser cutting machine with a nutating cutting head whose rotational axis is in an inclined plane. Two essential modules such as post-processor and cutting motion simulator was developed based on a commercial 3D CAD of UG-NX. The developed system was applied to three dimensional cutting products and showed the validity of the developed methods.

• Proceedings of the Korea Institute of Convergence Signal Processing
• /
• 2003.06a
• /
• pp.141-144
• /
• 2003

This paper proposes a design method of a CDBC(Continuous-time Deadbeat Controller)system that takes into account the response between the sampling instant and using second-order smoothing elements. The continuous deadbeat controller is composed of a serial integral compensator and a local feedback compensator introduced into the state feedback loop. A DC servo motor is chosen for implementing CDBC algorithm. Especially according to the variable input and disturbance, corresponding CDBC design method is suggested. A Matlab Simulink is used for simulation with the Motor parameter. By computer simulations, control inputs and system outputs are shown to have desirable property such as smoothness.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2007.05a
• /
• pp.379-382
• /
• 2007

The MEMS (Micro Electro Mechanical Systems) process is used in a micro/nano pattern manufacturing method. This method is based on the lithography technology. But the MEMS process has some problems such as complicated process, long processing time and high production costs. Many researchers are doing research in substitute manufacturing method to work out a solution to these problems. In this paper, we apply a dieless incremental forming technology to a substitute method of MEMS process. This dieless forming technology is using in the commercial scale sheet forming such as a prototype of automobile sheet parts. 5-axes CNC (Computerized Numeric Control) method are applied in this system to get a micro-scale dieless forming results. These 5-axes system are composed of precision AC servo motor stages (4-axes) and PZT actuator (1-axis). A PZT actuator is used in a precision actuating axis because it can be operated in the nano scale stroke resolution. This micro dieless incremental forming system has the advantage of minimization in manipulating distance and working space. As equipment and tools become smaller in size, minute inertia force and high natural frequency can be obtained. Therefore, high precision forming performance can be obtained. This allows the factory to quickly provide the customer with goods because the manufacturing system and process are reduced. To construct this micro manufacturing system, many technologies are necessary such as high stiffness frame, high precision actuating part, structural analysis, high precision tools and system control. To achieve the optimal forming quality, the micro dieless forming system is designed and made with high stiffness characteristic.

• Proceedings of the KIEE Conference
• /
• 1998.07b
• /
• pp.417-419
• /
• 1998

In a large diesel engine actuator position servo system, it is impossible to isolate an actuator fault from a load torque with conventional fault detection isolation (FDI) schemes because they are propagated through a channel. This paper deals with a parity equation based residual generation to isolate them in the system. The actuator fault is modelled by a multiplicative type fault that can be characterized as discrepancies between the nominal and actual plant parameters, whereas the load torque is modelled by an additive disturbance. The transformation implemented in the residual generator should be determined on-line to achieve the isolation. Simulation studies show the practical applicability of the FDI scheme.

• Proceedings of the KIEE Conference
• /
• 2002.07b
• /
• pp.897-899
• /
• 2002

BLDCM(Brushless D.C. Motor) is widely used industrial application because of high efficiency and high power density. Especially, In servo system and home appliance, BLDCM is very useful due to high control performance and low acoustic noise. In this paper, 2.5HP rated BLDCM controller and drive was developed for tread mill application. The prototype BLDCM has 4 poles rotor and 24 slots stator. Ferrite was used as a rotor magnet due to the cost and temperature characteristic. For the stable operation of tread mill, over current and high temperature can be detected by the DSP control1er. For the commutation signal, switching patterns from the sensorless circuit and hall sensor signal are used in the DSP controller.

• Proceedings of the KIEE Conference
• /
• 2004.11c
• /
• pp.738-740
• /
• 2004

The disturbance observer is effective in enhancing the performance of position control in high speed optical disk drive systems(ODDS). It is known that error based modified disturbance observer (EM-DOB) is more effective structure than general DOB. It has a simple structure and realization, but it loses robustness. We propose a dual modified disturbance observer(Dual mDOB). It consists of internal loop EM-DOB and external loop DOB. Those loops are designed for different objects. We see that the dual mDOB is an effective method for tracking performance.