• The Journal of Korea Robotics Society
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• v.8 no.2
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• pp.67-74
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• 2013

This paper presents interaction force control between a balancing robot and a human operator. The balancing robot has two wheels to generate movements on the plane. Since the balancing robot is based on position control, the robot tries to maintain a desired angle to be zero when an external force is applied. This leads to the instability of the system. Thus a hybrid force control method is employed to react the external force from the operator to guide the balancing robot to the desired position by a human operator. Therefore, when an operator applies a force to the robot, desired balancing angles should be modified to maintain stable balance. To maintain stable balance under an external force, suitable desired balancing angles are determined along with force magnitudes applied by the operator through experimental studies. Experimental studies confirm the functionality of the proposed method.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.340-345
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• 1994

Dynamic hybrid position/force control of flexible manipulators is proposed. First, a 2 D.O.F. flexible manipulator is modeled using the spring-mass model. Second, the equation of motion considering the tip constraints is derived. Third, hybrid position/force control algorithm is derived. In this control algorithm, the differentiable order of the desired trajectory and the stability condition are different from the case of rigid manipulators. Lastly, to verify the effectiveness of the proposed control algorithm, simulation results are presented.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.440-445
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• 1994

An application of H$_{\infty}$ synthesis to contact control of a manipulator is suggested. Based on computed torque linearization of a manipulator, a target dynamics for contact motion control is defined and used as a reference model. The target dynamics relates position and force errors through free motion impedance and force error compensators. The H$_{\infty}$ control synthesis is adopted to find an optimum the compensator for position tied force control in various directions of the end-effector. The optimization is performed on the augmented criteria, which trades off the sensitivity function of the errors and the input load at the joints. A design example of the compensator is provided that meets the design specifications.s.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.428-433
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• 1997

This paper presents a new control strategy for the position and force control of flexible manipulators. The governing equation of motion of a two-link flexible manipulator which features piezoceramic actuators bonded on each flexible beam is derived via Hamilton's principle. The control torque of the motor to command desired position and force is determined by a sliding mode controller on the basis of the rigid-mode dynamics. In the controller formulation, the sliding mode controller with perturbation estimation(SMCPE) is adopted to determine appropriate control gains. The SMCPE is then incorporated with the fuzzy technique to mitigate inherent chattering problem while maintaining the stability of the system. A set of fuzzy parameters and control rules are obtained from a relation between estimated perturbation and actual perturbation. During the commanded motion, undesirable oscillation is actively suppressed by applying feedback control voltages to the piezoceramic actuators. These feedback voltages are also determined by the SMCPE. Consequently, accurate force and position control of a two-link flexible manipulator are achieved. Computer simulations are undertaken in order to demonstrate the effectiveness of the proposed control methodology.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.12
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• pp.1034-1039
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• 2016

This paper presents the implementation and control of a small-scaled excavator system. The commercial miniature of an excavator system has been modified and its control hardware is embedded to access the feedback control. Encoder sensors are attached to the joint and a force sensor is mounted on the end-effector so that feedback position control is accessible as well as force control. The dynamic model of the excavator system is derived as a four linkage robot arm and its control performances are simulated. Experimental studies of contact force control tasks are conducted to test the control algorithm for the excavator system.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.2
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• pp.63-70
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• 2018

In this paper, the design of a novel 6-axis compliance device with force/torque sensing capability and the experiment results on force measurement are presented. Unlike the traditional control methods using a force/torque sensor with very limited compliance, the force control method employs a compliant device to provide sufficient compliance between an industrial robot and a rigid environment for more stable force control. The proposed compliance device is designed to have a diagonal stiffness matrix at the tip and uses strain gauge measurement which is robust to dust and oil. The measurement circuit is designed with low-cost IC chips however the force resolution is 0.04N.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.411-413
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• 1992

This paper proposes a simple and high performance hybrid position/force control of robots based on disturbance compensation by using the disturbance observer in task coordinate space. The disturbance observer linealizes system of robot manipulators in task coordinate space and realizes acceleration control. To realize the strict acceleration control, the disturbance observer whose input is a position signal by simple computation, works as if it were a disturbance detector. The inverse kinematics can be simplified, because the disturbance observer in task coordinate space compensates not only the disturbance but also the error due to the simplification of the inverse kinematics. The new strategy is applied to a three-degrees-of freedom direct drive robot. The robust and simple hybrid position/force control is realized experimentally.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.2
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• pp.207-216
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• 1991

In the case that the robot manipulator should respond to the variance and uncertainty of the environment in performing preforming precision tasks, it is indispensable that the robot utilizes the various sensors for intrlligence. In this paper, the robot force control method is implemented with a force/torque sensor, two personal computers, and a PUMA 560 manipulator for performing the various application tadks. The hybrid position/force control method is used to control the force and position axis separately. An interface board is designed to read the force/torque sensor output into the computer. Since the two computers should exchange the information quickly, a common memory board is designed. Before the algorithms of application tasks are developed, the basic force commands must be supplied. Thus, the MOVE-UNTIL command is used at the discrete time instant and, the MOVE-COMPLY is used at the continuous time instant for receiving the force feedback information. Using the two basic force commands, three application algorithms are developed and implemented for edge-following, insertion, and grinding tasks.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.539-542
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• 1996

The forces exerted on an object by the end-effectors of multi-manipulators are decomposed into the motion-inducing force and the internal force. Motion-inducing force effects the motion of an object and internal force can't effect it. The motion of an object can't track exactly the desired motion because of internal force component, therefore internal force component must be considered. In this paper using the resolved acceleration control method and the fact that internal force lies in the null space of jacobian matrix, we construct independently the position, motion-inducing force and internal force controller. Secondly we construct the robust controller to preserve the robustness with respect to the uncertainty of manipulator parameters.

• International Journal of Safety
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• v.1 no.1
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• pp.1-6
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• 2002

It is important to control the high accurate position and force to prevent unexpected accidents by a robot manipulator. Direct-drive robots are suitable to the position and force control with high accuracy, but it is difficult to design a controller because of the system's nonlinearity and link-interactions. This paper is concerned with the study of the stabilization force control of direct-drive robots. The proposed algorithm is consists of the feedback controllers and the neural networks. After the completion of learning, the outputs of feedback controllers are nearly equal to zero, and the neural networks play an important role in the control system. Therefore, the optimum adjustment of control parameters is unnecessary. In other words, the proposed algorithm does not need any knowledge of the controlled system in advance. The effectiveness of the proposed algorithm is demonstrated by the experiment on the force control of a parallelogram link-type robot.