• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.552-555
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• 1996

In this paper, we present a force control of a five-axes robot, using an impedance model. Tasks such as assembly, grinding, and deburring, which involve extensive contact with the environment, are better handled by controlling the forces of interaction between the manipulator and the environment. The five-link articulated robot is equipped with a wrist force sensor which consists of an array of strain gauges and can delineate the three components of the vector force along the three axes of the sensor coordinate frame, and the three components of the torque about these axes. For the precise control of the contact force, impedance models of a robot and the environment are defined. Experimental results are shown.

• Journal of Sensor Science and Technology
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• v.22 no.1
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• pp.28-37
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• 2013

This paper presents a fault-tolerant control technique for wind turbine systems with sensor and actuator faults. The control objective is to maximize power production and minimize turbine loads by calculating a desired pitch angle within their limits. Any fault with a sensor and actuator can cause significant error in the pitch position of the corresponding blade. This problem may result in insufficient torque such that the power reference cannot be achieved. In this paper, a fault-tolerant control technique using a robust dynamic inversion observer and control allocation is employed to achieve successful pitch control despite these faults in the sensor and actuator. The observer based detection method is used to detect and isolate sensor faults by checking whether errors are larger than threshold values. In addition, the control allocation technique is adopted to tolerate actuator fault. Control allocation is one of the most commonly used fault-tolerant control techniques, especially for over-actuated systems. Further, the control allocation method can be used to achieve the power reference even in the event of blade actuator fault by redistributing the lost torque due to erroneous pitch position into non-faulty blade actuators. The effectiveness of the proposed method is demonstrated through simulations with a benchmark model of the wind turbine.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.6
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• pp.650-657
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• 2013

This study uses a muscle activation sensor and elbow joint model to develop an estimation algorithm for human elbow joint torque for use in a human-robot interface. A modular-type MVS (Muscle Volume Sensor) and calibration algorithm are developed to measure the muscle activation signal, which is represented through the normalization of the calibrated signal of the MVS. A Hill-type model is applied to the muscle activation signal and the kinematic model of the muscle can be used to estimate the joint torques. Experiments were performed to evaluate the performance of the proposed algorithm by isotonic contraction motion using the KIN-COM$^{(R)}$ equipment at 5, 10, and 15Nm. The algorithm and its feasibility for use as a human-robot interface are verified by comparing the joint load condition and the torque estimated by the algorithm.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.4
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• pp.366-376
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• 2002

A sensor fault detection and isolation scheme(SFDIS) is adopted to improve the reliability of direct torque controlled induction motor drives and the experimental results are discussed. Major contributions include: experimental analysis of a few important sensor faults. design and implementation of the proposed SFDIS, and the fault tolerant control system(FTCS). Although the adopted SFDIS employs only one observer for residual generation, the system has the function of fault isolation that only multiple observer schemes can have. To verify the performance of the proposed scheme, the speed control system is designed for the 2.2kW direct torque controlled Induction motor. Hardware of the control system consists of a control board using TMS320OVC33 and a power stack using IPM. Experimental results for various type of sensor faults show the effectiveness of the SFDIS and the FTCS.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.6
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• pp.873-880
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• 2011

As environmental pollution, global warming, and exhaustion of fossil fuel become global issue recently, there has been strong research motivation to develop green energy technology. Along the same line of motivation, some research efforts have been put into the development of environment-friendly bicycle equipped with various smart energy technologies to increase the usability of the bicycle as short-distance transportation. Among the technologies related with new generation bicycle, PAS (power assist system) is one of the most important systems that are essential in efficiently integrating human power and the electrical power supplied by electric motor driven by battery. In this paper, a novel torque sensor technology which is core component for PAS is proposed. Unlike existing technologies, strain gauges are attached to rear shaft directly under the hub bearings, which eliminates the requirement of slip-ring, Furthermore, the sensor is able to not only measure the torque transmitted to driving axle by human but also estimate the position of the gear to which the chain is currently engaged.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.341-345
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• 2001

Recently, many examples of practical applications of the motors with reluctance torque, such as IPMSM, RM, etc. are reported. However, the problems of the torque ripple produced by the IPMSM, are also presented. The main reasons of the torque ripple generation are the structural imperfectness of the IPMSM and its control system, such as the cogging torque of the motor, the dead time of inverter, sensors offset, imbalance and non-linearity, and so on. In this paper, authors propose a suppression control method of the torque ripple for IPMSM utilizing the repetitive control with the Fourier transformer and a vibration signal detected by an acceleration sensor attached to the motor frame, considering periodicity of the motor torque ripple. An experimental system to simulate the compliant mechanical frame is constructed, and the effectiveness of the proposed method is confirmed by experimental results.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.12
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• pp.119-126
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• 2004

Permanent magnetic gears are magneto-mechanical devices that are widely used to replace the ordinary mechanical gear and to transmit torque without the mechanical contact. This study investigates the characteristics of touch free permanent magnetic gear according to the employing systems. The effect of the magnetic torque is analyzed by using 3 dimensional Finite Element Method (FEM). To estimate the transmission torque of FEM model, the numerical results are compared with the experimental results. The influences of geometry size, magnet number on transmission torque are obtained. As results of this paper, it is confirmed that the transmission torque behavior is associated with the configuration of the magnet numbers and the air gap between the two permanent magnetic gears.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.5
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• pp.407-412
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• 2015

This paper presents the design of a lab-built powered knee prosthesis based on a BLDC motor, a sensored impedance control using a force sensor, and a sensorless impedance control through torque estimation. Firstly, we describe the structure of the lab-built powered knee prosthesis and its limitations. Secondly, we decompose the gait cycle into five stages and apply the position-based impedance control for the powered knee prosthesis. Thirdly, we perform an experiment for the torque estimation and the sensorless impedance control of the prosthesis. The experimental results show that we can use the torque estimation to control the low impedance during the swing phase, although the estimated torque data has a delay compared with the measured torque by a load cell.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.3
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• pp.238-244
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• 2004

To monitor the torque of an induction motor using current, the accurate identification of the motor parameters is very important. In this study, the motor parameters such as rotor resistance, stator and rotor leakage inductance, mutual inductance are estimated for torque monitoring and indirect vector control. Estimated parameters are used to monitor the torque of vector controlled induction motor without any speed measuring sensor. Stator current is measured to estimate the magnetizing current which is used to calculate flux linkage, rotor velocity and motor torque. From the experiments, the proposed method shows a good estimation of the motor parameters and torque under the normal rotational speed.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.5
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• pp.99-105
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• 2004

Internet provides the useful method to monitor the current states of the machine tool no matter where a personnel monitors it. In this paper, a monitoring method of the torque of the machine tool's spindle induction motor using interne is suggested. To estimate the torque accurately, spindle driving system of an CNC lathe is divide into two parts, induction motor part and mechanical part attached to the induction motor spindle. Magnetizing current is calculated from the measured 3 phase currents without speed sensor used to estimate the torque generated by an induction motor. In mechanical part of the system, some of the torque is used to overcome friction and remaining torque is used to overcome cutting force. An equation to estimate friction torque is drawn as a function of cutting torque and rotation speed. Graphical programming is used to implement the suggested algorithm. to monitor the torque of an induction motor in real time and to make the estimated torque monitored on client computers. Torque of the spindle induction motor is well monitored on the client computers in about 3% error range under various cutting conditions.