• 로봇학회논문지
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• 제12권3호
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• pp.356-364
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• 2017

This paper presents a force control based on the observer without taking any force or torque measurement from the robot which allows realizing more stable and robust human robot interaction for the developed multi-functional upper limb rehabilitation robot. The robot has four functional training modes which can be classified by the human robot interaction types: passive, active, assistive, and resistive mode. The proposed observer consists of internal disturbance observer and external force observer for distinctive performance evaluation. Since four training modes can be quantitatively identified as impedance variation, position-based impedance control with feedback and feedforward controller was applied to the assistive training mode. The results showed that the proposed sensorless observer estimated cleaner and more accurate force compared to the force sensor and the impedance controller embedded with the proposed observer completed the assistive training mode safely and properly.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1407-1410
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• 1997

Advanced sensor design and filtering technology have been studied to obtain information for condition monitoring and diagnostics inmachining processes. To develope and economic monitoring system in end milling processes, indirect and reliable type of cutting force estimators were required. In this paper, an estimation method of cutting forces during end milling processes was studied through the measurement of current signals obtained from spindle and feeddrive motors. Cutting force and torque models were derived from the cutting geometry in down milling processes. Relationships between motor currents and cutting forces were also developed in the form of AC and DC components from the developed force models. The validity of the cutting force estimator was confirmed by the experiments under various cutting conditions.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.249-253
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• 1994

In machine tools, frictional force exists between the table and the bed, and in ballscrews. In this paper, feed motor current is used to measure the motor torque and frictional force. A hall sensor is used to measure the feed motor current. Some frictional pheonomina in feed drice systems, such as, the relationship between feedrate and frictional force, lubrication conditions and frictional force, and feed direction and frictional force, are obtained. Generally, the friction behavior is in good agreement with Stribeck's curve. However, the data shows significant scatter when feedrate is high.

• 대한기계학회논문집A
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• 제34권6호
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• pp.771-780
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• 2010

본 논문에서는 제작이 용이한 십자형 구조를 기본구조로 사용하여 판스프링 고정단을 가진 유연한 6축 로드셀을 설계하였다. 이를 위하여 유한요소법해석을 이용하여 강체 고정단과 판스프링 고정단에 대한 변형 분석을 하였으며 이로부터 특성이 우수한 6축 힘/토크 센서를 설계하였다. 변형률 분포를 이용하여 각 축의 하중에 대한 출력변형률이 비슷한 수준이 되도록 스트레인 게이지 위치를 정하고 상호간섭 변형률이 최소화 되도록 이들로 연결된 브리지회로를 구성하였다. 강체 고정단 대신에 스프링판 고정단을 이용하면 고정 경계부의 조건을 변화시킬 수 있어서 십자형 로드셀의 특성을 획기적으로 개선시킬 수 있었다. 치수 변경을 통하여 설계된 6축 로드셀에 대한 상호 간섭오차는 모든 축에서 0으로 계산되었으며 각 축에서 발생하는 출력변형률 값도 $400\;{\mu}m/m$의 비슷한 수준으로 결정되었다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.694-697
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• 1996

The aim of this work for 5 years from 1994 is to develop a multi-fingered robot hand and its control system for grasp and manipulation of objects dexterously. Since the robot hand is still being developed, a commercialized robot hand from Barrett Company is utilized to implement a hand controller and control algorithm. For this, VME based motion control and interface boards are developed and multi-sensors such as encoder, force/torque sensor, dynamic sensor and artificial skin sensor are partly developed and employed for the grasping control algorithm. In oder to handle uncertainties such as mechanical idleness and backlash, a fuzzy rule based grasping algorithm is also considered and tested with the developed control system.

• 한국전자통신학회논문지
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• 제19권1호
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• pp.85-92
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• 2024

본 논문에서는 로봇팔의 선단을 잡고 원하는 위치로 이동시켜서 작업을 직접 교시하는 직감적인 교시 및 제어를 시스템을 개발하였다. 개발된 시스템은 로봇팔 선단부의 위치 방향 및 자세 방향 힘을 측정하는 6축힘 센서, 선단부에서 측정된 힘에 의한 로봇팔 관절 속도제어 명령어 생성 알고리즘, 자체 제작한 6축 로봇팔 및 제어 시스템으로 구성된다. 선단부 핸들러에 부착된 힘센서를 통해 로봇팔 조작자가 핸들러를 조종하는 위치 자세의 6차원의 힘/토크를 감지하고 이를 선단부 조종속도 명령으로 변환하여 6축 로봇팔을 제어한다. 연구 방법의 검증은 자체 제작된 6축 로봇으로 실행하였으며, 조종자의 핸들러 조정을 통한 작업교시에 의한 실험을 통해 제안한 힘 센서기반 로봇 선단 제어 방법이 성공적으로 동작함을 확인하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.1169-1172
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• 1995

In this paper, the external force control and hybrid force control algorithms are proposed to apply Deburring process. the purpose of adjust which can be implemented to on unknown environments, adaptive control law(MRAC) is adopted. IF a model system is given, the plant system can be controlled on the way which we will introduce to. We showed the validation and the possibility of Deburring process with multi-dimensional force control through experiments. the experimental result show the validity of Deburring in the robot manipulator.

• 산업기술연구
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• 제24권B호
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• pp.207-214
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• 2004

An active stick which supplies force feedback to the operator is developed in this study. A mathematical model of the active stick is derived, and compared with the experimental result. It turns out that the frictional torque due to the mechanical contacts of several parts of the stick is one of the major barriers to achieve high precision operation of the stick. The frictional effect of the stick is cancelled out by using a friction observer. The efficacy of the friction observer is verified through the numerical simulation. Because of the observer dynamics, there are some limitations in exact recovering the static friction and Stribeck effect. However, the friction observer follows the real friction on the average. It's anticipated that the application of the friction observer to the closed loop control of the active stick improves the performance of the displacement versus force characteristics, which will be proved experimentally in the further study.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.32-34
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• 1997

For a given brushless DC linear motor, we suggest the numerical prediction methods to analyze it's thrust characteristics. First, we calculate the magnetic flux density by the finite element method, and we then compute the maximum thrust with three computational methods - a Lorentz equation, a Maxwell stress method and a virtual work method. To confirm the accuracy of the computational methods, we measure the thrust of the linear motor made by our laboratory with a force-torque sensor. Also, we calculate the thrust by the measured back electromotive force. To choose the appropriate method for a specified application, we compare the maximum thrusts of the computational method and the calculation by the back electromotive force with the measured one. We conclude that the Maxwell stress method is turned out the best because it has the most accurate results among three computational methods and it is more convenient than the calculation method by the back electromotive force.

• 대한의용생체공학회:의공학회지
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• 제32권2호
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• pp.93-104
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• 2011

The purpose of this study was to investigate lower-limb joint torque of the two groups as it changed by somatosensory stimulation during the descent down three stairs of different heights and to describe the difference between the two groups, which are young people group and elderly people group. Subjects of each groups climbed down a stair at four stimulation conditions, which are non-stimulation, tibialis anterior tendon stimulation, achilles tendon stimulation, tibialis anterior - achilles tendon stimulation. Motion capture data were collected using 3D optoelectric motion tracking system that utilizes active infrared LEDs, near infrared sensor and force plate. The obtained motion capture data was used to build 3D computer simulation model. The results show that lower-limb joint torque of the two groups changed with somatosensory stimulation as they descended the stairs and the joint torque of the two groups differed from each other.