• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.528-532
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• 1991

Having very small linear displacement, piezoelectric actuators have been restricted in robotic application as positioning devices. In this paper, a mechanical amplifier was developed to enhance the displacement of piezoelectric actuator and the corresponding driving circuit was designed. This equipment was integrated as a robotic wrist having 2 D.O.F micropositioning capability. Each joint was analysed in mechanical and dynamic view points. Experimental result showed that this device has Some hysteresis but could be used as vibratory robotic wrist with relatively high frequency. For more fine positioning control, a closed loop approach must be taken into account.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5587-5594
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• 2012

Determination of the soil-water characteristic curve is one of the most important things to solve geotechnical engineering problems. Expecially, convenient and reliable method to measure the soil-water characteristic curve during drying and wetting cycles is required with lower labor input, more independence from operator experience, and shorter testing time than other available methods. Many measurement methods including the flow pump system have been developed to characterize the soil-water characteristic curve for the several decades. This study measured the soil-water characteristic curve during drying and wetting cycles using a suction control technique with the flow pump system. Two test materials were used for determination of the soil-water characteristic curve, and it is concluded that suction control technique is suitable for determination of the soil-water characteristic curve and characterization of the hydraulic hysteresis with varying test conditions. Especially, the suction control technique can reduce error of measurement and save time in measuring the soil-water characteristic curve due to automated system and high degree of precision.

• Journal of Electrical Engineering and Technology
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• v.3 no.4
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• pp.538-545
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• 2008

This paper attempts to summarize torque control strategy for high performance SR drive. There are primarily two strategies for torque control. One method is direct torque control, which uses the simple control scheme and hysteresis controller to reduce the torque ripple. Another method is indirect torque control, which uses the complicated algorithms or simple distribution function to distribute each phase torque and obtain current command. The current controller is used to control phase torque by a given current command. In order to compare these two strategies of torque control, five torque control methods are introduced. The advantages and disadvantages of each method are presented. At last, they are verified by some simulations and experimental results.

• International Journal of Control, Automation, and Systems
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• v.4 no.6
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• pp.756-762
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• 2006

Shape Memory Alloy(SMA) actuators, which have the ability to return to a predetermined shape when heated, have many potential applications such as aeronautics, surgical tools, robotics and so on. Although the conventional PID controller can be used with slow response systems, there has been limited success in precise motion control of SMA actuators, since the systems are disturbed by unknown factors beside their inherent nonlinear hysteresis and changes in the surrounding environment of the systems. This paper presents a new development of a SMA position control system by using a self-tuning fuzzy PID controller. This control algorithm is used by tuning the parameters of the PID controller thereby integrating fuzzy inference and producing a fuzzy adaptive PID controller, which can then be used to improve the control performance of nonlinear systems. The experimental results of position control of SMA actuators using conventional and self-tuning fuzzy PID controllers are both included in this paper.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.10
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• pp.1529-1535
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• 2012

This paper presents the application algorithm for speed control of Switched Reluctance Motor. The conventional PI controller has been widely used in industrial applications. But it is very difficult to find the optimal PI control gain. Fuzzy control does not need any model of plant. It is based on plant operator experience and heuristics. The proposed fuzzy logic modifier increases the control performance of conventional PI controller. Simulation and experimental results show that the proposed fuzzy control method was superior to the conventional PI controller in the respect of system performance. The experiments are performed to verify the capability of proposed control method on 6/4 salient type SRM.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.615-619
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• 2000

This paper presents an implementation of digital motion control system of Surface Permanent-Magnet Synchronous Motor(SPMSM) vector drives with a direct torque control(DTC) using the 16bit DSP TMS320F240 The DSP controller enable enhanced real time algorithm and cost-effective design of intelligent control for motors which can be yield enhanced operation fewer system components lower system cost increased efficiency and high performance The system presented are stator flux and torque observer of stator flux feedback model that inputs are current and voltage sensing of motor terminal and angle for a low speed operating area two hysteresis band controllers an optimal switching look-up table and IGBT voltage source inverter by using fully integrated control software. The developed control system are shown a good motion control response characteristic results and high performance features using 1.0Kw purposed servo drive SPMSM.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.277-280
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• 2001

This paper presents a speed sensorless implementation of digital speed control system of Surface Permanent-Magnet Synchronous Motor(SPMSM) drives with a direct torque control(DTC). The system presented are stator flux and torque observer of stator flux feedback control model that inputs are current and voltage sensing of motor terminal with estimated rotor angle for a low speed operating area, two hysteresis band controllers, an optimal switching look-up table, rotor speed estimator, and IGBT voltage source inverter by using fully integrated control software. The developed speed sensorless control system are shown a good motion control response characteristic results and high performance features using 1.0Kw purposed servo drive SPMSM.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.397-400
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• 2001

This paper presents a implementation of digital sensorless position control system of surface permanent-magnet synchronous motor (SPMSM) drive with a direct torque control (DTC). The system are stator flux and torque observer of stator flux feedback control model that inputs are current and voltage sensing of motor terminal with estimated rotor angle for a low speed operating area, two hysteresis band controllers, an optimal switching look-up table, rotor speed estimator, and IGBT voltage source inverter by using fully integrated control software. The developed sensorless control system are shown a good motion control response characteristic results and high performance features using 1.0 (kW) purposed servo drive SPMSM.

• Korean Journal of Materials Research
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• v.10 no.10
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• pp.703-708
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• 2000

As the engine design changes to get high efficiency and performance of commercial diesel engine, surface w wear of the earn follower becomes an important issue as applied load increasing at the contact face between cam follower and cam. We developed the ceramic cam follower made of sili$\infty$n nitride ceramic which was more wear resistant than the cast iron or sintered metal cam follower. Ceramic cam follower was made by direct brazing of thin ceramic disk to steel body using an active brazing alloy without the interlayer. In-situ crowning(R), resulted from the difference of thermal expansion coefficient between ceramic and carbon steel after direct brazing without any stress-relieving inter]ayer, could be controlled. When a earbon steel was heated above $A_{c1}$ point and then c$\infty$led, the expansion curve represented a hysteresis. Appropriate crowning was achieved below the $A_{c1}$ point(about $723^{\circ}C$) and crowning increased with brazing temperature exponentially above the $A_{c1}$ point. Optimum brazing temperature range was from 700 to $720^{\circ}C$. We developed successfully the ceramic cam follower having appropriate crowning and being inexpensive. Also we could successfully control the crowning of ceramic earn follower by hysteresis behavior of thermal expansion of earbon steel during direct brazing process.

• Journal of Power Electronics
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• v.5 no.1
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• pp.11-19
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• 2005

This paper describes the two control techniques to perform the sensorless vector control of a PMSM by injecting the high frequency voltage to the stator terminal. The first technique is the estimation algorithm of the initial rotor position. A PMSM possesses the saliency which produces the ellipse of the stator current when the high frequency voltage is injected into the motor terminal. The major axis angle of the current ellipse gives the rotor position information at a standstill. The second control technique is a sensorless control algorithm that injects the high frequency voltage to the stator terminal in order to estimate the rotor position and speed. The rotor position and speed for sensorless vector control is calculated by appropriate signal processing to extract the position information from the stator current at low speeds or standstill. The proposed sensorless algorithm using the double-band hysteresis controller exhibits excellent reference tracking and increased robustness. Experimental results are presented to verify the feasibility of the proposed control schemes. Speed, position estimation and vector control were carried out on the floating point processor TMS320VC33.