• Transactions on Control, Automation and Systems Engineering
• /
• v.4 no.4
• /
• pp.277-282
• /
• 2002

This paper proposes a nonlinear adaptive controller based on back-stepping method for tracking reference substrate concentration by manipulating dilution rate in a continuous baker's yeast cultivating process in stirred tank bioreactor. Control law is obtained from Lyapunov control function to ensure asymptotical stability of the system. The Haldane model for the specific growth rate depending on only substrate concentration is used in this paper. Due to the uncertainty of specific growth rate, it has been modified as a function including the unknown parameter with known bounded values. The substrate concentration in the bioreactor and feed line are measured. The deviation from the reference is observed when the external disturbance such as the change of the feed is introduced to the system. The effectiveness of the proposed controller is shown through simulation results in continuous system.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2000.10a
• /
• pp.299-303
• /
• 2000

A brushless linear motor is suitable for operation with higher speed and precision. Since it does not involve mechanical coupling, linear driving force can be applied directly. Conventional PID and fuzzy controllers are implemented and performance results using those controllers are compared. Along with better simulated performance observed using fuzzy controller, further fabrication is to be included with various empirical results. Several system operational characteristics have been observed. Typical nonlinearities as friction, cogging and torque or thrust ripple that might deteriorate system performance would be tackled using presumably effective method such as neural network based learning controller.

• Journal of Institute of Control, Robotics and Systems
• /
• v.18 no.2
• /
• pp.87-93
• /
• 2012

In this paper, a formation guidance method for UAVs (Unmanned Aerial Vehicles) to simulate the formation flight of birds proposed. The proposed method solves all issues of approaching for formation, formation keeping, and scarce chance to be collided with each UAV during formation process. Also, we design the feedforward controller to compensate the change of speed and heading for maneuvering of the leader UAV and the feedback controller to consider the response lag of the system. The stability and performance of the proposed controller is verified via numerical simulations of the full 6-Dof model of UAV.

• Proceedings of the KIEE Conference
• /
• 1991.07a
• /
• pp.771-776
• /
• 1991

In this paper. an indirect adaptive controller for manipulator which is composed of two controller structure is considered. One is feedforward controller in which the dynamics equation solved and the other is feedback controller in which the output error compensated. This controller has a good performance, but the computation burden of the feed forward controller keep from real time control. At this point, we proposed the two time adaptive controller where the sampling time of the feedforward controller is quite longer than that of the feedback controller. By the computer simulation, this proposed two time adaptive controller shows good performance in the view of accuracy in spite of decreasing computational burden.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.13 no.3
• /
• pp.322-327
• /
• 2003

The water level of a steam generator of pressurized light water nuclear Power generator is known as a subject whose control is difficult because of a shrinking and swelling effect that is been mutually contradictory in a variation of feed water. In this paper, a neural network model selects first coordinative controller by a inappropriate gain of two PI controllers and the selected controller＇s gain is tuned by a fuzzy self-tuner. Model inputs consist of the water level, the feed water, and the stream flow. One controller of both coupling controllers whose gain is handled firstly is decided based upon above data. The proposed method can analyze patterns of signals using the characteristic of neural networks and select one controller that needs to be tuned through the observed result in this paper. If one controller between both the water level controller and the feed water controller is selected by the neural network model then a gain of the PI controller is suitably tuned by the fuzzy self-tuner. Rules of the fuzzy self-tuner drew from the pattern of input and output data. In the summary, the goal of this Paper is to select the suitable controller and tune the control gain of the selected controller suitably through such two processes.

• Journal of Biomedical Engineering Research
• /
• v.28 no.6
• /
• pp.768-776
• /
• 2007

A new type of the fluid circulation blood pressure simulator was proposed to enhance the blood pressure simulator used for the development and evaluation of automatic sphygmomanometers. Various pressure waveform of fluid flowing in the pipe was reproduced by operating the proportional control valve after applying a pressure on the fluid in pressurized oil tank. After that, appropriate fluid was supplied by operating the proportional control valve, which enabled to reproduce various pressure wave of the fluid flowing in the tube. To accomplish this work, the mathematical model was carefully reviewed in cooperating with the proposed simulator. After modeling the driving signal as input signal and the pressure in internal tube as output signal, the simulation on system parameters such as internal volume, cross-section of orifice and supply pressure, which are sensitive to dynamic characteristic of system, was accomplished. System parameters affecting the dynamic characteristic were analyzed in the frequency bandwidth and also reflected to the design of the plant. The performance evaluator of fluid dynamic characteristic using proportional control signal was fabricated on the basis of obtained simulation result. An experimental apparatus was set-up and measurements on the dynamic characteristic, nonlinearity, and rising and falling response was carried out to verify the characteristic of the fluid dynamic model. Controller was designed and thereafter, simulation was performed to control the output signal with respect to the reference input in the fluid dynamic model using the proposed proportional control valve. Hybrid controller combined with an proportional controller and feed-forward controller was fabricated after applying a disturbance observer to the control plant. Comparison of the simulations between the conventional proportional controller and the proposed hybrid simulator indicated that even though the former showed good control performance.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.28 no.1
• /
• pp.40-47
• /
• 2004

This paper proposes a three-axis coupling controller designed to improve the contouring accuracy in machining of 3D nonlinear contours. The proposed coupling controller is based on an innovative 3D contour error model and a PID control law. The novel contour error model provides almost exact calculation of contour errors in real-time for arbitrary contours and can be integrated with any type of existing interpolator. In the proposed method, three axes of motion are coordinated by the proposed coupling controller along with a proportional controller for each axis. The proposed contour error model and coupling controller are evaluated through computer simulations. The simulation results show that the proposed 3-axis coupling controller with the new contour error model substantially can improve the contouring accuracy by order of magnitude compared with the existing uncoupled controllers in high-speed machining of nonlinear contours.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2001.04a
• /
• pp.513-518
• /
• 2001

As the machining depth increases, the drilling torque increases and fluctuates and the risk of drill failure also increases. Hence, drilling torque control is very important to prevent the drill from failure. In this study, a PID controller was designed to control the drilling torque in a machining center. The plant including the feed drive system, cutting process, and spindle system was modeled for controller design. The Ziegler-Nichols rule was used to determine the controller gain and control action times. The root locus plot was used to tune the controller gain for a certain cutting condition. Also, suggested was a simple method to obtain the tuned controller gain for an arbitrary cutting condition not using the Ziegler-Nichols rule and root locus plot. The cutting torque control, performance of the designed controller and the effect of gain tuning on the control performance were examined.

• 제어로봇시스템학회:학술대회논문집
• /
• 1989.10a
• /
• pp.553-556
• /
• 1989

Nowadays in power plant feed water control, it is very important to retain the stable drum level though power changes very fast. For the stable drum level in power plant, we have to model our plants and get the system functions. We make the L.Q. controller by using these functions and apply it to these systems. And we get the more stable drum level which is controlled by feed water qualities.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.1 s.94
• /
• pp.265-271
• /
• 1999

In the feed drive systems or the spindle systems of machine tools that consist of many mechanical components, a torsional vibration is often generated because of its elastic elements in torque transmission-Generally, the accuracy of motion control system is strongly influenced by the dynamic behavior of coupled transmission components Especially, a torsional vibration caused by the elasticity of mechanical elements might deteriorate the quick movement of system and lead to shorten the life time of the mechanical transmission elements. So, it is necessary to analyze the electromechanical system mathematically to optimize the dynamic characteristics of the feed m1d spindle system. In this paper, based on the DC motor model, a model of electro-drive system with motor has been developed and an optimal criterion for tuning the gain of speed controller is discussed. The frequency bandwidth of the system and the damping ratio in time domain are optimal design specifications for the gain adjustment speed controller. The gains of PI speed controller are then derived from the bandwidth and damping ratio, and those relationships have been classified.