• 제어로봇시스템학회논문지
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• 제19권12호
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• pp.1160-1166
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• 2013

This paper presents feedforward controllers to improve the control performance of the motion and grasping force of a surgical instrument used in an MIS (Minimally Invasive Surgery) robot. The surgical instrument has a long distance between the drive motors and its active joints. Therefore, the gripper on the instrument is controlled by a cable drive mechanism, which generates a coupled motion between the wrist joint and the grip direction. In order to solve the problem, this paper analyzes the pulley composition of the surgical instrument and proposes feedforward controllers to eliminate the coupled motion. Furthermore, feedforward controllers to regulate the grasping force are proposed to deal with another coupling problem between the grasping force of the instrument and the motion of the instrument joints. The experimental results demonstrate the improved control performance of the motion and grasping force of the instrument.

• 한국정밀공학회지
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• 제26권1호
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• pp.89-96
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• 2009

This paper describes the intelligent robot's hand with three finger sensors for a humanoid robot. In order to grasp an unknown object safely, the intelligent robot's hand should measure the mass of the object, and determine the grasping force using the mass, finally control the grasping force using the finger sensors and the controller. In this paper, the intelligent robot's hand for a humanoid robot was developed. First, the six-axis force/moment sensor was manufactured. second, three finger force sensors were designed and fabricated, third, the high-speed controller was manufactured using DSP(digital signal processor), finally, the characteristic test for determining a grasping force and for grasping an unknown object safely It is confirmed that the hand could grasp an unknown object safely.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 추계학술대회 학술발표 논문집
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• pp.568-576
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• 1998

In this thesis discuss with a flexible robotic finger design and controller which is used for the micro flexible robotic finger. So, miniaturization, precision, controller for the control of grasping force and actuator were needed. And, even if we develop a new actuator and controller, in order to use on real system, we must considerate of a many side problem. In a force control of micro flexible finger for grasping an object, the fingertip's vibration was more important task of accuracy control. And, controller were adopt the PD/PI mixed type fuzzy controller. The controller were consist of two part, one is a PD type fuzzy controller for increase the rising time response, the other is a PI type fuzzy controller for decrease of steady-state error. Especially, in a PD type fuzzy controller, we used only seven rules. And, for a PI controller, we adopt a reset factor for the control of input values. so, we have overcome the exceed of controller's input range. For the estimate of ontroller's utility and usefulness, we have experiment and computer simulation of three cases. First, we consider of unit force grasping control for a task object, which is 0.03N. Second, bounding grasping force control which is add to a sinusoidal force on the unit force. At this cases the task force is (0.03+0.01 sin wt N). And consider of following of rectangular forces.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.229-232
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• 2002

This paper describes the development of robot's finger 3-axis force sensor that detects the Fx, Fy, and Fz simultaneously fur stably grasping an unknown object. In order to safely grasp an unknown object using the robot's fingers, they should detect the force of gripping direction and the force of gravity direction, and perform the force control using the detected farces. The 3-axis force sensor that detects the Fx, Fy, and Fz simultaneously should be used for accurately detecting the weight of an unknown object of gravity direction. Thus, in this paper, robot's finger for stably grasping an unknown object is developed. And, the 3-axis farce sensor that detects the Fx, Fy, and Fz simultaneously fur constructing a robot's finger is newly modeled using several parallel-plate beams, and is fabricated. Also, it is calibrated, and evaluated.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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• pp.601-610
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• 1993

With the purpose of labour reduction in tea plucking operation with portable type machine, the influence of frame angles and tea leaves weight on the grasping forces of each finger were investigated. At the measurement of the grasping force of each finger except for thumb, grip strength dynamometers were attached at the grasping position of the frame instead of handle grips. A series of measurement was carried out changing frame angles of the tea plucking machine and the weight of tea leaves. With the obtained results of the experiments , the influences of the frame angles and the weight of the tea leaves on the grasping forces of each finger were analyzed. Some reasonable suggestions for the labour reduction in the tea plucking operation with portable type machine were obtained in the aspect of normalizing the balance of the grasping force on each finger and these suggestions are expected to contribute the labour reduction of the tea plucking operation.

• 대한기계학회논문집A
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• 제41권5호
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• pp.415-420
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• 2017

과소 구동 전동의수는 가벼우며 비교적 경제적이라는 장점이 있다. 본 연구에서는 적응파지가 가능한 과소 구동 전동의수를 대상으로 경제적인 파지력 제어 시스템을 제안하였다. 근전도 신호로 구동되는 메인 케이블의 장력으로 파지력이 결정되므로 장력에 따라 사용자의 피부에 부착된 진동모터를 구동하는 촉감기반 피드백 시스템을 구성하였다. 진동 신호에 대한 사용자의 감각적 판단을 기반으로 파지력을 추정하고 제어하기 위하여 파지력과 진동 신호 간의 적절한 변환 관계를 수립하고 시제품 성능시험을 하였다. 최소한의 훈련으로 사용자들은 비교적 정확하게 파지력을 제어할 수 있었다.

• 센서학회지
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• 제15권6호
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• pp.411-416
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• 2006

This paper describes the development of a 3-axis finger force sensor to grasp an unknown object safely in an intelligent robot's hand. In order to safely grasp an unknown object, robot's hand should measure the weight of an object and the force of grasping direction simultaneous. But, in the published papers, the grippers and hands equippd with the force sensor that could only measure the force of grasping direction, and grasped objects using their sensors. These grippers and hands can't safely grasp unknown objects, because they can't measure the weight of it. Thus, it is necessary to develop 3-axis force sensor that can measure the weight of an object and the force of grasping direction for an intelligent gripper. In this paper, 3-axis finger force sensor to grasp an unknown object safely in an intelligent robot's hand was developed. In order to fabricate a 3-axis finger force sensor, the sensing elements were modeled using parallel plate beams, and the theoretical analysis was performed to determine the size of sensing elements, then the 3-axis finger force sensor was fabricated. Also, the characteristic test of the developed 3-axis finger force sensor was performed.

• Transactions on Control, Automation and Systems Engineering
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• 제4권1호
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• pp.2-8
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• 2002

This paper discusses haptic display for grasping a virtual object by two fingers. Much research has been done on fundamental analysis for stability of haptic display. But it is difficult to apply the results immediately to grasping situations by two fingers, since the studies usually deal with a single device and a single object and the fingertip force in grasping situations has two components, internal and external components. The conventional methods, which specify the coupling impedance at each contact point separately, have no other alternative but to specify the impedance for the sum of the internal and external components. So even if only the impedance for the external force should be changed, the impedance for the internal force is also changed at the same time. In this paper, a new method, in which the coupling impedance is specified separately for the internal and external forces, is proposed and the stability of the proposed method is discussed using passivity analysis for 1 -DOF(Degree-Of-Freedom) system. Finally, some experiments are performed to study the effects of the proposed method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 추계학술대회 논문집 학회본부
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• pp.455-458
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• 1988

In this paper, a grasping force control of robot hand is presented with consideration of workpiece dynamics. It is difficult to control a manipulator without the knowledge of Its dynamics, because its handling with unknown workpiece may bring about overshoots and vibrations. Then it is necessary to adjust control gains according to the handling workpieces in order to achieve good control performances. The authors propose a new control strategy which uses adaptive observer and VSS (${\underline{V}}ariable$ ${\underline{S}}tructure$ ${\underline{S}}ystem$) controller to subdue these overshoots and vibrations. Some simulations of the proposed method are carried out for a grasping system to control the grasping force to various workpieces, whose dynamics cannot be known in advance.

• 한국산업융합학회 논문집
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• 제18권3호
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• pp.173-180
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• 2015

In this paper, we propose a new precise control technology of robotic gripper for assembling and handling of part. When a robot manipulator interacts mechanically with its environment to perform tasks such as assembly or edge-finishing, the end-effector is thereby constrained by the environment. Therefore grasping force control is very important, since it increases safety due to monitoring of contact force. A comparison of various force control architecture is reported. Different force control methods can often be configured to achieve similar results for a given task, and the choice of control algorithm depends strongly on the application or on the characteristics of a particular robot. In the research, the adjustable gripping force can be controlled and improved the accuracy using the artificial intelligence techniques.