• 한국정밀공학회지
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• 제22권3호
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• pp.29-37
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• 2005

In this study, the control of the free surface deformation of a magnetic fluid for the change in electromagnetic force is discussed. The free surface of magnetic fluid is formed by the balance of surface force, gravity, pressure difference, magnetic normal pressure and magnetic body force. Magnetic fluid in characteristics of fluid adjusted to the opposite direction of the gravity direction. Thus, the device of a magnetic fluid proposed the complete zero-leakage sealing, oscillator for surface control, boundary layer control, MHD, flow control, flow using magnetic levitation system and surface actuator. This study show the deformation of surface rise due to the intensity of the magnetic field and possibility of two-dimensional control of magnetic fluid through the feedback data of hall sensor.

• 한국정밀공학회지
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• 제19권3호
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• pp.137-143
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• 2002

This paper presents the In-process compensation to control cutter runout and improve the machined surface quality. Cutter runout compensation system consists of the micro-positioning servo system with piezoelectric actuator which is embeded in the sliding table to manipulate radial depth of cut in real-time. Cutting force feedback control was proposed in the angle domain based upon repetitive learning control strategy to eliminate chip load variation in end milling process. Micro-positioning control due to adaptive actuation force response improves the machined surface quality by compensation runout effect induced cutting force variation. This result will provide lots of information to build-up the preciswion machining technology.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.575-578
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• 1995

In general, the control of robot manipulator is classified into position control and force control. Position controllers give adequate performance when a manipulator is following a trajectory through space and end-effector has no contact with environment. However for most tasks performed by robot manipulator in industry, contact is made between the end-effector and manipulator's environment, so position control may not suffice. The objective of this study is to control both position of a manipulator and the contact forces generated at the hand by using a conceptually simple control law. Position and force control problem is decoupled into subtasts via taskspace formulation and inverse dynamics. Then, the position controllers are designed for the task space variable which represent tangent motion and the forte controllers are designed for the lash space variables which represent normal force.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.605-609
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• 1996

Continuous sliding mode control is applied to turning process for cutting force regulation. The highest feedrate compatible with the allowable cutting force is applied in rough cutting process such that maximum productivity is ensured and tool breakage is avoided. The programmed feedrate is overridden after the control algorithm is carried out. However, most CNC lathe manufacturers offer limited number of data bits far feedrate override, thus resulting in nonlinear behavior of the machine tools. Such nonlinearity brings “quantized” effect, and the optimal faedrate is rounded off before being fed into the CNC system. To compensate for this problem, continuous sliding mode control is applied. Conventional switching control law at a sliding surface is replaced by a smooth control interpolation in a selected boundary layer to avoid the excitation of high-frequency dynamics. Simulation results are presented in comparison with those obtained by applying adaptive control.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 B
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• pp.657-660
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• 2003

Control of multi-link robot arms is a very difficult problem because of the highly nonlinear dynamics. Decentralized control scheme is developed for control of robot manipulators based on RBF(Radial Basis Function) Neural Networks. RBF Neural Networks is used to approximate the coupling forces among the joints, coriolis force, centrifugal force, gravitational force, and frictional force. The compensation controller is also proposed to estimate the bound of approximation error so that the chattering effect of the control effort can be reduced. The proposed scheme does not require an accurate manipulator dynamic, and it is proved that closed-loop system is asymptotic stable despite the gross robot parameter variations. Numerical simulations for two-link robot manipulator are included to show the effectiveness of controller.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1091-1096
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• 2007

This paper describes the development of a small lens molding system for manufacturing the small lens like lens of a cellular phone, a small digital camera and so on. In order to manufacture a small lens, firstly, the raw material for lens with spherical shape should be manufactured by processing a glass, secondly, the mold inserted the raw material for lens should be heated till its molding temperature in the electric furnace, finally, the small lens is manufactured by applying the force using pressuring control system. In this paper, the small lens molding system with the function of force control and velocity control was developed. It is composed of a electric furnace and its temperature control system, a pressuring control system, a body, and so on. The temperature characteristic test of the electric furnace, and the force and velocity characteristic test of the pressuring control system were carried out. It was confirmed that the developed system had good functions for manufacturing a small lens.

• 한국정밀공학회지
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• 제25권2호
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• pp.57-64
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• 2008

This paper describes the development of a small lens molding system for manufacturing the small lens like lens of a cellular phone, a small digital camera and so on. In order to manufacture a small lens, firstly, the raw material for lens with spherical shape should be manufactured by processing a glass material, secondly, the mold inserted the raw material for lens should be heated till its molding temperature in the electric furnace, finally, the small lens is manufactured by applying the force using pressuring control system. In this paper, the small lens molding system with the function of force control and velocity control was developed. It is composed of an electric furnace and its temperature control system, a pressuring control system, a body, and so on. The temperature characteristic test of the electric furnace, the force and velocity characteristic test of the pressuring control system were carried out. It was confirmed that the developed system had good functions for manufacturing a small lens.

• 대한기계학회논문집A
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• 제31권1호
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• pp.18-25
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• 2007

Linear motor is easily affected by load disturbance, force ripple, friction, and parameter variations because there is no mechanical transmission to reduce the effects of model uncertainties and external disturbance. These nonlinear effects have been reduced for high-speed/high-accuracy position control either through the better motor design or via the better control algorithm that can compensate the nonlinear effects. In this paper, a nonlinear adaptive control algorithm is designed and applied for the position control of permanent magnet linear synchronous motor. In order to estimate and compensate the nonlinear effects such as friction and force ripple, the estimation and the nonlinear adaptive control laws are derived based on the virtual control input and a suitable Lyapunov function. The proposed controller is evaluated through the computer simulations. The control algorithm is also implemented to a DSP board and interfaced to the PMLSM for verifying the realtime control performance.

• 드라이브 ㆍ 컨트롤
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• 제13권3호
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• pp.32-38
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• 2016

For this paper, the position-control performances of dual EHA(electro-hydrostatic actuator) systems were investigated according to two cases wherein the double-rod- and single-rod-type hydraulic cylinders were combined. Since the control performance is significantly dependent on the load conditions including external forces such as the inertia load, it is proposed here that the two sub-EHAs are driven by separate position and force controllers, instead of two identical position controllers. According to the simulation results, the best performance was achieved by the position-controlled single-rod-type EHA that was combined with a force-controlled double-rod-type EHA. As the force-controlled double-rod-type EHA compensated for the external loads on the position-controlled single-rod-type EHA, the position-control performance was not influenced by external forces including the inertia load. In addition, the position-controlled single-rod-type EHA contributed to the enhancement of the damping ratio by absorbing the pressure peaks through its internal accumulator. Due to the symmetrical piston areas, the double-rod-type EHA is more suitable for force control than the single-rod- type EHA.

• 제어로봇시스템학회논문지
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• 제21권7호
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• pp.595-601
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• 2015

This paper presents an unified chassis control with electronic stability control (ESC) and active front steering (AFS) under lateral force constraint on AFS. When generating the control yaw moment, an optimization problem is formulated in order to determine the tire forces, generated by ESC and AFS. With Karush-Kuhn-Tucker optimality condition, the optimum tire forces can be algebraically calculated. On low friction road, the lateral force in front wheels is easily saturation. When saturated, AFS cannot generate the required control yaw moment. To cope with this problem, new constraint on the lateral tire force is added into the original optimization problem. To check the effectiveness of the propose method, simulation is performed on the vehicle simulation package, CarSim.