• Journal of the Korean Society for Precision Engineering
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• v.18 no.8
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• pp.96-106
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• 2001

As the drilling depth increases, the cutting torque increases and fluctuates, which can lead to the machine tool vibration, severe tool wear, and catastrophic tool breakage. Hence, cutting torque control is very important to improve productivity in drilling. In this paper, a PID controller was designed to control the drilling torque. The plant including the feed drive system, cutting process and spindle drive system was modeled for controller design. The Ziegler-Nichols method was used to determine the controller gain and control action times and 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 method and the root locus plot. The performance of the designed controller and the effect of controller gain tuning were verified from experiments.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.363-366
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• 2009

The maximum output torque developed by the machine is dependent on the allowable current rating and maximum voltage that the inverter can supply to the machine. Therefore, to use the inverter capacity fully, it is desirable to use the control scheme considering the voltage and current limit condition, which can yield the maximum torque per ampere over the entire speed range. This controller is controlled speed and current using hybrid PI(HBPI) controller and estimation of speed using ANN. Also, this paper is proposed control of maximum torque per ampere(MTPA) of induction motor. This strategy is proposed which is simple in structure and has the honest goal of minimizing the stator current magnitude for given load torque. The performance of the proposed induction motor drive with maximum torque control using HBPI controller is verified by analysis results at dynamic operation conditions.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.812-815
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• 2003

Most of all, DTC drive is very simple in its implementation because it needs only two hysteresis comparator and switching vector table for both flux and torque control. The switching strategy of a conventional direct torque control scheme which is based on hysteresis comparator results in a variable switching frequency which depends on the speed, flux, stator voltage and the hysteresis of the comparator. The amplitude of hysteresis band greatly influences on the drive performance such as flux and torque ripple and inverter switching frequency. In this paper the influence of the amplitudes of flux and torque hysteresis bands and sampling time of control program on the torque and flux ripples are investigated. Simulation results confirm the superiority of the DTC under the proposed method over the conventional DTC.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.4
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• pp.268-277
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• 2009

This paper presents an DTC-PWM (Direct Torque Control-Pulse Width Modulation) of PMSM (Permanent Magnet Synchronous Motor). The proposed DTC-PWM method combines a conventional DTC and PWM approach for switching signal generation. The actual torque is estimated by the torque estimator in conventional method, but the switching signal is generated by PWM method according to the switching rules and torque error. A effective voltage vector and zero vector are used to generate the switching signals and asymmetric switching method is applied. A simple calculation of PWM without any complex determination of space vector can assure the constant switching frequency with an constant torque and flux. The proposed torque control scheme for PMSM is verified by experimental results.

• The Journal of Korea Robotics Society
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• v.5 no.1
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• pp.48-54
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• 2010

Ankle-foot orthosis with a pneumatic rubber actuator, which is intended for the assistance and the enhancement of ankle muscular activities was developed. In this study, the effectiveness of the system was investigated during plantarflexion motion of ankle joint. To find a effectiveness of the system, the subjects performed maximal voluntary isokinetic plantarflexion contraction on a Biodex-dynamometer. Plantarfexion torque of the ankle joint is assisted by subject's soleus muscle that is generated when ankle joint do plantarflexion motion. We used the muscular stiffness signal of a soleus muscle for feedback control of ankle-foot orthosis as physiological signal. For measurement of this signal, we made the muscular stiffness force sensor. We compared a muscular stiffness force of a soleus muscle between with feedback control and without it and a maximal plantarflexion torque between not wearing a ankle-foot orthosis, without feedback control wearing it and with feedback control wearing it in each ten elderly adults. The experimental result showed that a muscular stiffness force of a soleus muscle with feedback control was reduced and plantarflexion torque of an ankle joint only wearing ankle-foot orthosis was reduced but a plantarflexion torque with feedback control was increased. The amount of a increasing with feedback control is more higher than the amount of a decreasing only wearing it. Therefore, we confirmed the effectiveness of the developed ankle-foot orthosis with feedback control.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.4
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• pp.309-316
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• 2016

In this study, we described the design of a three-axis force/torque sensor for measuring the force and torque in a lower-limb rehabilitation robot. The three-axis force/torque sensor is composed of Fx force sensor, Fz force sensor and Tz torque sensor. The sensing element for Fx force sensor and Tz torque sensor is used in a two-step parallel plate beam, and that of Fz force sensor is used in a parallel plate beam. The rated loads of Fx force sensor, Tz torque sensor and Fz force sensor are 300 N, 15 N m and 100 N, respectively. The three-axis force/torque sensor was designed using the finite element method, and manufactured using strain-gauges. The three-axis force sensor was further characterized. As a result, the interference error of the three-axis force/torque sensor was < 1.24%, the repeatability error of each sensor was < 0.03%, and the non-linearity was < 0.02%.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.1
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• pp.9-16
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• 2011

Research on ISA(Integrated Starter/Alternator) receives wide attention as system voltage is increased to 42V Based on requirement of starter and alternator for the conventional vehicle, system requirement and specification are determined. Also to control proposed system, suitable control methods are proposed. Main control issues with ISA are whether torque assist is required and if so how much torque is needed. In this paper, vehicle performance with various control methods and capacity are simulated and simulation results are analyzed. Vehicle performance is analyzed with vehicle simulator. For the simulation, suitable ISA model is also developed.

• The Journal of Korea Robotics Society
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• v.13 no.3
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• pp.157-163
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• 2018

This paper deals with the development and application of control algorithms for series elastic relief robots for rescue operations in harsh environment like disasters or battlefield. The joint controller applied in this paper has a cascade structure combining inner loop for torque control and outer loop for position control. The torque loop contains feedforward and feedback controller and disturbance observer for independent, decentralized joint control. The effect of the elastic component and motor dynamics are treated as the nonlinear disturbance and compensated with the disturbance observer of torque controller. For the collision detection, Band Designed Disturbance Observer is configured to recognize/respond to external disturbance robustly in the continuously changing environment. The controller is applied to a 7-dof series elastic manipulator to evaluate the torque tracking and collision detection/response performance.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.99-102
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• 2006

This paper proposes a DITC(Direct Instantaneous Torque Control of SRM (Switched Reluctance Motor) using a novel 4-level converter for smooth torque control and high efficiency. DITC of SRM is very useful for smooth torque control, but the driving efficiency is low due to advanced current that does not produce torque. For the high efficiency control of SRM, fast excitation and demagnetization of phase current are required. A novel 4-level converter and a new control scheme are present to improve the driving efficiency. The proposed DITC of SRM using 4-level converter is verified by computer simulation.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.891-894
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• 2004

This paper estimate coefficient of adhesion through speed sensor-less vector control and load torque disturbance observer used for maximum tractive force control. And also proposes anti-slip control algorithm, which controls torque force of motor in order to keep the estimated adhesion force in maximum adhesion by controlling PI torque with the differential value of estimated adhesion force coefficient.