• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.3
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• pp.260-269
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• 1988

Conventional torque and position control scheme is developed to control a robot manipulator using the knowing mass of links of load. This paper presents a torque and position control method which performs under unknown mass of links or load. This method takes full advantage of known parameters and servo error in joint coordinate space. We illutrate the theory with some simulations and show that the results is effective.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.450-455
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• 1989

In this paper we investigate the application to the motion control of n-link robotic manipulators of recently developed stable factorization approach to tracking and disturbance rejection. Given control scheme consists of an approximate "Computed Torque" based upon a simplified model together with additional state feedback and feedforward compensation, and then, nonlinear control gain has more useful than constant control gain to guarantee robustness to parameter uncertainty and external disturbance. At this stage, we design high gain nonlinear state feedback controller and simulate this controller at the SCARA type robot manipulator of two joint.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.559-563
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• 2000

In this paper we describe a method for aligning a robot gripper using image information. The region of gripper is represented from HSI color model that has major advantage of brightness independence. In order to extract the feature points for vision based position control, we find the corners of gripper shape using polygonal approximation method which determines the segment size and curvature of each points. We apply the vision based scheme to the task of alignment of gripper to reach the desired position by 2 RGB cameras. Experiments are carried out to exhibit the effectiveness of vision based control using feature points from polygonal approximation of gripper.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.4
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• pp.25-32
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• 1994

This paper presents a robust impedance controller design to coordinate a robot manipulator under system uncertainties while regulating external forces. By an impedance approach, the relationship between the motion and external forces is defined. Due to the system uncertainties, two kind of sliding mode control schemes based on the impedance approach are derived to ensure that the manipulator end-effector follows a desired trajectory and the force applied to end effector is regulated according to a target impendance. A stability condition is shown according to a sliding condition. To evaluate the devised control scheme, a numerical example is shown.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.3873-3879
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• 2010

Home service robot are not working in the fixed task such as industrial robot, because they are together with human in the same indoor space, but have to do in much more flexible and various environments. Most of them are developed on the base of the wheel-base mobile robot in the same method as a vehicle robot for factory automation. In these days, for holonomic system characteristics, omni-directional wheels are used in the mobile robot. A holonomicrobot, using omni-directional wheels, is capable of driving in any direction. But trajectory control for omni-directional mobile robot is not easy. Especially, azimuth control which sensor uncertainty problem is included is much more difficult. This paper develops trajectory controller of 3-wheels omni-directional mobile robot using fuzzy azimuth estimator. A trajectory controller for an omni-directional mobile robot, which each motor is controlled by an individual PID law to follow the speed command from inverse kinematics, needs a precise sensing data of its azimuth and exact estimation of reference azimuth value. It has imprecision and uncertainty inherent to perception sensors for azimuth. In this paper, they are solved by using fuzzy logic inference which can be used straightforward to perform the control of the mobile robot by means of the fuzzy behavior-based scheme already existent in literature. Finally, the good performance of the developed mobile robot is confirmed through live tests of path control task.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.229-232
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• 2005

In this paper, an image-based "approach-align -grasp" visual servo control design is proposed for the problem of object grasping, which is based on the binocular stand-alone system. The basic idea consists of considering a vision system as a specific sensor dedicated a task and included in a control servo loop, and we perform automatic grasping follows the classical approach of splitting the task into preparation and execution stages. During the execution stage, once the image-based control modeling is established, the control task can be performed automatically. The proposed visual servoing control scheme ensures the convergence of the image-features to desired trajectories by using the Jacobian matrix, which is proved by the Lyapunov stability theory. And we also stress the importance of projective invariant object/gripper alignment. The alignment between two solids in 3-D projective space can be represented with view-invariant, more precisely; it can be easily mapped into an image set-point without any knowledge about the camera parameters. The main feature of this method is that the accuracy associated with the task to be performed is not affected by discrepancies between the Euclidean setups at preparation and at task execution stages. Then according to the projective alignment, the set point can be computed. The robot gripper will move to the desired position with the image-based control law. In this paper we adopt a constant Jacobian online. Such method describe herein integrate vision system, robotics and automatic control to achieve its goal, it overcomes disadvantages of discrepancies between the different Euclidean setups and proposes control law in binocular-stand vision case. The experimental simulation shows that such image-based approach is effective in performing the precise alignment between the robot end-effector and the object.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.758-761
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• 2003

This paper introduces a method that can detect obstacles and corridor environments from the images captured by a CCD camera in an automobile or mobile robot is proposed. Processing the input dynamic images in real time requires high performance hardware as well as efficient software. In order to relieve these requirements for detecting the useful information from the images in real time, a "Moving Window" scheme is proposed. Therefore, detecting the useful information, it becomes possible to search the obstacles within the driving corridor of an automobile or mobile robot. The feasibility of the proposed algorithm is demonstrated through the simulated experiments of the corridor driving.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1966-1971
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• 2005

Though several previous anti-windup techniques have been proposed, they are limited to linear systems or friction is not considered. Thus this paper proposes a compensation scheme for input-constrained robot systems with friction to cope with the windup phenomenon and shows its effectiveness by simulations. Given a feedback linearizing controller for a robot system designed without considering its input constraint, an additional dynamic compensator is proposed to account for the constraint. The dynamic anti-windup is based on the minimization of a reasonable performance index, and properties of the resulting closed-loop are presented.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.532-535
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• 1997

This paper describes the design of a fuzzy-logic controller for a differential-drive mobile robots. This controller uses absolute position information to modify control parameters to compensate the orientation error. CC-Control method is compensated for the internal error by wheel encoders and the fuzzy-logic control provides compensation for external errors. The validities of the proposed scheme is evaluated using simulation.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.252-257
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• 1990

For the position control of BL-DC motors, 2.phi.-3.phi. conversion unit, hysteresis band device, and PWM pulse generation are required. By utilizing a single-chip processor INTEL 8097BH, we cover all required functions. As a result, no analogue device is employed in this control scheme, so that it makes BL-DC motor controller simple and flexible. Furthermore, the single-chip processor is utilized for the nonlinear coordinate transformation which is necessary for the linearization of the motor system.