• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.2
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• pp.297-304
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• 1997

This paper presents a systematic design method of an anti-swing control law for overhead cranes. A velocity servo system for the trolley of a crane is designed based on the dynamics of the trolley and its load. The velocity servo system compensates for the effects of load swing on the trolley dynamics so that the velocity servo is independent of load swing. The velocity servo system is used for the design of a position servo system for the trolley via the loop shaping method. The position servo system and the swing dynamics of the load are then used to design an angle control system for load swing based on the root locus method. The combined position servo and the angle control systems constitute the overall control system. In the presence of low frequency disturbances, the proposed control law guarantees accurate position control for the trolley and fast damping for load swing. Furthermore, the performance of the proposed control law is independent of the mass of the load. Experimental results on a prototype crane show the effectiveness of the proposed anti-swing control law.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.2
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• pp.124-130
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• 2003

The electro-hydraulic servo system with a servo valve is applied widely in force control. However, the composition of control system using a servo valve is difficult due to nonlinearities in the servo valve, such as square-root terms in flow equation. The electro-hydraulic servo system using a DDV(Direct Drive Valve) instead of a servo valve was proposed and it's characteristics was estimated. The DDV and whole system are modelled by parameter identification using the input-and-output data, then the models are verified by the comparison of simulation with experiment. Also, the state feedback controller has been designed based on this model, then the performance of the electro-hydraulic force servo system using a DDV is evaluated by simulation and experimental results.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.7
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• pp.1186-1192
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• 1994

This paper presents an algorithm to design a robust digital model following servo control system in which optimal linear quadratic regulator problem is used to design the control system that make the step/ramp response of the plant kept close to a specified ideal step/ramp response of the model. The quadratic criterion function for a continuous system is used to design the robust digital servo control system. The feasibility of the design technique is shown by the simulation and the proposed method is applied to the speed control of DC servo motor.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.12
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• pp.45-56
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• 2002

A pneumatic servo system requiring a fine gap control in a photo-electric sensor which is used for a LCD array detection device is introduced. The gap controlled by the pneumatic servo system remains within around 50~80 ${\mu}{\textrm}{m}$, and the system possesses an effect to eliminate undesirable particles on the LCD plate by blowing air out. The air flow rate is initially controlled by a servo valve and expanded by a booster valve, thus the controlled air pressure contributes to maintaining an appropriate gap between the LCD plate and photo-electric sensor An air floating plate of two degrees of freedom is designed and fabricated, and a fine tilting motion control is also implemented by assigning different gap commands. The pressure control and direct gap control are proposed, and each performance is verified experimentally.

• IEMEK Journal of Embedded Systems and Applications
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• v.14 no.6
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• pp.339-346
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• 2019

Multi-axis servo systems are widely used in various fields such as industiral systems for improving production efficiency, robotics and complex systems where many mechanical devices and sensor systems are connected. Such a servo system requires that the servo control technique to realize the synchronization of the drive shaft in the steady state and transient conditions and to control so as to follow the target track in order to improve product precision and production efficiency. In addition, embedded type hardware is required for smooth control of the entire multi-axis system. Therefore, this paper uses hardware based on FPGA which is widely used in digital signal processing field and various control system because hardware design change is easy and parallel processing is possible. In addition, Labview based servo motor control program was studied that can control the servo motor by ensuring the performance and flexibility of the FPGA and follow the target trajectory according to various speed processing and accurate timing synchronization.

• Journal of Drive and Control
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• v.16 no.1
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• pp.29-35
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• 2019

The control performance of hydraulic systems is basically influenced by the performance of electrohydraulic servo valve incorporated in a hydraulic control system. In this study, a control design was proposed to improve the control performance of a servo valve with a non-contact eddy current type position sensor. A mathematical model for the valve was obtained through an experimental identification process. A PI-D control together with a feedforward (FF) control was applied to the valve. To further improve the dynamic response of the servo valve, an input shaping filter (ISF) was incorporated into the valve control system. Finally, the effectiveness of the proposed control system was verified experimentally.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.4
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• pp.277-283
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• 2003

Recently, near-field recording (NFR) disk drive schemes have been proposed with a view to increasing recording densities of hard disk drives. Compared with hard disk drives. NFR disk drives have narrower track pitches and are exposed to more severe periodic disturbances resulting from eccentric rotation of the disk. It is difficult to meet servo system design specifications for NFR disk drives with conventional VCM actuators in that the servo system for an NFR disk drive generally requires a feater gain and higher bandwidth. To tackle the problem various dual-stage actuator systems composed of a microactuator mounted on top of a conventional VCM actuator have been proposed. This article deals with the problem of designing a tracking servo system far an NFR disk drive adopting a dual-stage actuator. We summarize design constraints pertaining to the dual-stage servo system and present a new servo scheme using iterative teaming control. We design feedback compensators and an iterative teaming controller for a target plant and verify the validity of the proposed control scheme through a computer simulation.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.2
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• pp.121-126
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• 2000

In the fast sampling limit the delta operator model tends to the analog system model. This fundamental property of the delta operator model unifies continuous and discrete time control system. In this paper we study robust linear optimal model following servo system in the presence of disturbances and parameter perturbations. A technique to directly design the generalized differential operator based unified control system that covers both differential operator based continuous time and delta operator based discrete time case is presented. The quadratic criterion function for a linear system is used to design the robust unified servo control system The characteristics of the proposed servo system are analysed and simulated to verify the robustness.

• Journal of Power Electronics
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• v.4 no.4
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• pp.228-236
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• 2004

This paper describes the optimal current-control of a permanent magnet synchronous motor by the use of robust and simple current controllers, based upon the analytical procedure known as the inverse LQ (ILQ) design method. The ILQ design method is a strategy for finding the optimal gains based on pole assignment without solving the Riccati equation. It is very important to keep the motor in robust servo-lock. By experiments and simulations, we will show that the ILQ optimal servo-system with servo-lock is more insensitive at low speeds to variations in armature inductance than the standard PI servo-system. Variations in armature inductance have the greatest influence on the responses of a servo-system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.424-427
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• 2002

Pneumatic control systems have the potential to provide high output power to weight and size ratios at a relatively low cost. However, they are mainly employed in open-loop control applications where positioning repeatability is not of great importance. This paper presents precision positioning control of pneumatic servo cylinder with on-off valve, Pneumatic low-friction cylinder with servo valve and DC servo motor under parameter variations. Basically positioning control uses PID controller, where needs a linearized model. A neural network is added to a PID controller to compensator nonlinearity of the system and an influence of friction force is consider as disturbance. The performances of the proposed algorithms were compared by experiments with them of PID controller. From those experiments is was shown that the proposed algorithms are more efficient about settling time, steady 7tate error and overshoot than PID control algorithm.