• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.269-272
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• 2003

Industry is now seeing a dramatic increase in robot simulation and off-line programming. In order to use off-line programming effectively, the simulated workcell has to be identical to the real workcell. This requires an efficient and accurate method for the workcell calibration. Currently used techniques in the industry, however, are typically time-consuming, expensive and therefore not suitable for in-process application. This is because most of these techniques are based on the so-called “absolute calibration” method. In contrast to absolute method, relative calibration only measures the difference of an interested object relative to a standard reference. Owing to the small measurement range requirement, relative calibration method is very cheap and can achieve very high accuracy. In this paper the relative method is applied to calibrate an entire grinding workcell. Linear gauge is the only measurement device used. This workcell calibration includes tool center point (TCP) calibration and work object frame calibration. Due to the efficiency of the calibration algorithm and the simplicity of the calibration setup, the described calibration procedure can be done in process.

• 한국정밀공학회지
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• 제31권4호
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• pp.319-326
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• 2014

Accurate estimation of the robot's position has an important role in autonomous navigation. Odometry is one of the most widely used techniques for mobile robot positioning. However, odometry has a well-known drawback that the position errors are accumulated when the travel distance increases. The UMBmark method is the conventional odometry calibration scheme for two wheel differential mobile robots. In the UMBmark method, the approximations for small angles are used in order to simplify the calculations. In this paper, we propose the new calibration scheme by using experimental orientation errors. Kinematic parameters can be calculated accurately without approximations by using experimental orientation errors. The numerical simulation and experimental results show that the odometry accuracy can be improved by the proposed method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.813-816
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• 1991

Direct-drive SCARA-type industrial robots are increasingly used in the assembly process of small mechanical parts as well as electronic components, which uses direct-drive (DD) motors instead of reduction gear-type conventional motors for the actuators of manipulator arms. There are many advantages in using DD motors for robots, such as no backlash, low friction, high mechanical stiffness capability for fast and precise arm control, and high repeatability of positioning. However, there exist a number of difficulties which must be overcome to ensure proper construction and operation; increasing effects of load veriation and nonlinear and coupling dynamics, severe vibration caused by resonance of the manipulator components and low mechanical damping, etc. In order to handle these difficulties, lots of efforts have been made such as reduction of the arm inertia and elimination of the resonance, Performance evaluation of a recently developed, domestic DD robot shows that it works excellently compared with conventional robots. It, however, requires proved reliability and price competitiveness against its foreign counterparts.

• 동력기계공학회지
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• 제15권4호
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• pp.48-53
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• 2011

Upon reviewing recent trends for robots, it can be seen that robots are gradually being miniaturized. However, most commercially available speed reducers have limitations in terms of structure and vibration when applied to small robots. In this respect, a tooth profile manufactured using thin plates was designed using balls and data analyzed related to numerical and FEM analysis. The speed reducer was manufactured to check their performance. The manufactured thin plate type speed reducer imposes less compressive stress on its tooth profile and balls, which can greatly increase feasibility.

• 소음진동
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• 제7권3호
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• pp.387-392
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• 1997

This paper concerns a SCARA robot with the flexible forearm linked to the rigid upper arm. The equations of motion are derived by the Lagrangian mechanics. For controller design, the perturbation approach is taken to separate the original equations of motion into linear equations describing small perturbed motions and nonlinear equations describing purely rigid motion of the robot. To effect the desired payload motion, open loop control inputs are determined based on the inverse dynamics of the latter. In order to reduce the positional error during maneuver, an active vibration suppression is done. To this end, a feedback control is designed for robustness against disturbance on the basis of the linear equations and the LQR theory modified to have a prescribed degree of stability. The proposed control scheme shows satisfactory performances in experiments as well as in numerical simulations.

• 전력전자학회논문지
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• 제17권3호
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• pp.252-258
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• 2012

This paper studies the power line communication method with splitting of power transmission interval in the small DC power system using pulse width modulation. The method divides the entire interval for transmitting power and data into a power transmission interval where power is supplied to a load and a data transmission interval where power from the power supply to the load is disconnected. The circuit is designed for the implementation to separate the power line from the power supply and load. The results of tests show the feasibility of the proposed power line communication method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 D
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• pp.2806-2808
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• 2005

The Controller Area Network (CAN) is being widely used for real-time control application and small-scale distributed computer controller systems. When the stuff bits are generated by bit-stuffing mechanism in the CAN network, it causes jitter including variations in response time and delay. In order to eliminate this jitter, stuff bit must be controlled to minimize the response time and reduce the variation of data transmission time. At first, this paper shows that conventional CAN protocol causes the transmission time delay. Secondly, this paper proposes the method to reduce the stuff bits by restriction of available identifier. Finally, data manipulation method can be reduced the number of stuff-bits in the data field. The proposed restriction method of ID and manipulating data field are pretty useful to the real-time control strategy with respect to performance. These procedures are implemented in local controllers of the ISHURO (Inha Semyung Humanoid Robot).

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.246-248
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• 2005

The Controller Area Network (CAN) is being widely used for real-time control application and small-scale distributed computer controller systems. However, CAN may exhibit unfair behavior under heavy traffic conditions. When there are both high and low priority messages ready for transmission, the proposed precedence priority filtering method allows one low priority message to be exchanged between any two adjacent higher priority messages. In this way, the length of each transmission delays is upper bounded. These procedures are implemented as local controllers for the ISHURO (Inha Semyung Humanoid RObot).

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.168.4-168
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• 2001

A great many species of fish congregate in schools, reducing the risk of being eaten by predators and giving one of the considerable survival advantages for fishes. Such a fish school is self-organized only due to individual behaviors for matching the speed and direction with the neighboring fishes. It is interesting to simulate these fish school by small robots, because we can understand how the group structure emerges from the interaction among neighboring individuals. We use a nice simulator for Khepera robot presented by Oliver Michel. It is shown that the Khepera simulator is easily applied to fish school due to the algorithm introduced by I Aoki. The simulator includes sensor noise so appropriately that the simulator can be transferred easily to the real environment. The results of simulation are given as follows: (1) The stability as a group is shown by plotting mean deviations from the center of group ...

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국제학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.1014-1017
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• 1988

Direct-drive robots have excellent features including no backlash, small friction, and high mechanical stiffness. However, dynamic coupling among joints as well as nonlinear effects become more prominent than traditional robots with reducers. Another critical issue is that the robot becomes more sensitive to the change of load. In this paper, we develop a simple current feedback scheme for reducing the influence of dynamic coupling and load sensitivity on the direct-drive robots. The method is implemented on a 2 d.o.f. planar direct-drive robot. Then the validity of the method is demonstrated through experiments.