• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.2
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• pp.108-115
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• 1999

This paper proposes the robot inverse calibration method using a neural networks. A highorder networks called Pi-Sigma networks has been used. The Pi-Sigma networks uses linear summing units in the hidden layer and product unit in output layer. The inverse calibration model which compensates the difference of joint variables only between measuring value and analytic value about the desired pose(position orientation) of a robot is proposed. The compensated values are determined by using the weights obtained from the learning process of the neural networks previously. To prove the reasonableness the SCARA type direct drive robot(4-DOF) and anthropomorphic robot(6-DOF) are simulated. It shows that the proposed calibration method can reduce the errors of the joint variables from $\pm$3 to $\pm$0.1.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.331-336
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• 1995

In this past decade, industrial robot have substituted human workers successfully in certain areas, however, the applications are limited due to the shortcoming in their mechanism and control strategies. Many researchers, therefore, have focused on improving the mechanical and sensory capabilities. Developing mult-degree-of-freedom end effectors, in other words robot hands, is one of the topics that researchers have begun to improve the limitation. A set of direct drive type servo-pneumatic finger joint has been developed for a dexterous robot hand. To control the pneumatic finger joints, a prototype 4/3-way proportional control valve has been designed and tested as a preliminary, research for the control of the pneumatic finger joints. A series of experiments have been conducted to verify the performance characteristics of the valve and the conventional proportional error contral with minor-loop compensation has been used to control the anguar position of the finger joints.

• International Journal of Control, Automation, and Systems
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• v.6 no.1
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• pp.76-85
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• 2008

Motivated by the fact that in many industrial robots the joint velocity is estimated from position measurements, the trajectory tracking of robot manipulators with output feedback is addressed in this paper. The fact that robot actuators have limited power is also taken into account. Let us notice that few solutions for the torque-bounded output feedback tracking control problem have been proposed. In this paper we contribute to this subject by presenting a theoretical reexamination of a known controller, by using the theory of singularly perturbed systems. Motivated by this analysis, a redesign of that controller is introduced. As another contribution, we present an experimental evaluation in a two degrees-of-freedom revolute-joint direct-drive robot, confirming the practical feasibility of the proposed approach.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.12
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• pp.86-94
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• 1997

This paper proposes the robot inverse calibration method using a neural networks. A high-order networks called Pi-Sigma networks has been used. The Pi-Sigma networks uses linear summing units in the hidden layer and product unit in output layer. The inverse calibration model which compensates the diff- erence of joint variables only between measuring value and analytic value about the desired pose(position, orientation) of a robot is proposed. The compensated values are determined by using the weights obtained from the learning process of the neural networks previously. To prove the reasonableness, the SCARA type direct drive robot(4-DOF) and anthropomorphic robot(6-DOF) are simulated. It shows that the proposed calibration method can reduce the errors of the joint variables from .+-. 5 .deg. to .+-. 0.1 .deg. .

• Journal of Electrical Engineering and information Science
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• v.1 no.1
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• pp.39-44
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• 1996

In this paper, adaptive controller with switching action is designed for rigid body robot manipulators to ensure the uniform stability of the manipulator system without a priori knowledge of the unmodeled dynamics. It will be shown that the parameter estimates are bounded independent of the other closed-loop signals boundedness, and also shown that the tracking error belongs to the normalized error bound via mathematical analisys. The robustness and performance of the proposed adaptive controller is investigated for the two-link direct drive manipulator actuated by VRM(Variable Reluctance Motor).

• 제어로봇시스템학회:학술대회논문집
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• 1988.10b
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• pp.1006-1013
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• 1988

We have shown how unstructured modeling was used to derive a general stability condition in Part 1. In Part 2, we focus on the particular dynamics (structures modeling) of the robot manipulator and environment. Using rigid body dynamics, the stability condition for the direct drive robots has been achieved in terms of the Jacobian and robot tracking controller. Combining the structured and unstructured modeling, a stability condition for a particular application can be obtained. This approach has been used to analyze compliant motion on the University of Minnesota robot using a feedforward torque controller. We have obtained a stability condition for this application. Through both simulation and experiment, the sufficiency of this condition has been demonstrated. For a sufficient stability condition, recall that if the condition is satisfied, then the stability is guaranteed; however, if the condition is violated, no conclusion can be made.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.2
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• pp.232-240
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• 1998

This paper deals with a hybrid position/force control of a robot which is moving on the constrained object with constant force. The proposed controller is composed of a position and force controller. The position controller has a nonlinear compensator which is based on the dynamic robot model and the force controller is attached by feedforward element. A direct drive robot with hard nonlinearity which is controlled by the proposed algorithm has moved on the constrained object with a high stiffness and low stiffness. The results show that the proposed controller has more vibration suppression effects which is occurred to the constrained object with a high stiffness, than a existing feedback controller, and accurate force control can be obtained by comparatively a small feedback gain.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.11
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• pp.950-957
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• 1989

We have shown how unstructured modeling was used to derive a general stability condition in Part 1. In Part 2, we focus on the particular dynamics (structured modiling) of the robot manipulator and environment. Using rigid body dynamics, the stability condition for the direct drive robots has been achieved in terms of the Jacobian and robot tracking controller. Combining the structured and unstructured modeling, a stability condition for a particular application can be obtained. This approach has been used to analyze compliant motion on the University of Minnesota robot using a feedforward torque controller. We have obtained a stability condition for this application. Through both simulation and experiment, the sufficiency of this condition has been demonstrated. For a sufficient stability condition, recall that if the condition is satified, then the stability is guaranteed` however, if the condition is violated, no conclusion can be made.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.472-475
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• 1997

The principle objective of this paper is to explain and demonstrate the advantage of the output-feedback controller proposed by Ailon in [61 by using simulation and experimental results. Namely, the goal of this study is to design and implement a real-time controller for set-point regulation of a one-link rigid robot manipulator with unknown parameters using only position measurement. For implementation a direct drive one-link rigid robot manipulator is constructed and a TMS320C40 DSP systems board is used in implementing real-time control algorithm.

• Proceedings of the KIPE Conference
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• 1996.06a
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• pp.47-51
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• 1996

In this paper, we propose a method for compliance control of a SCARA type 2-freedom direct drive(DD) manipulator. Each joint of the manipulator is driven by a travelling ultrasonic motor(USM). The travelling USM has good some characteristics over conventional servo motors such as compact size, light weight, silent motion, high torque and high speed response. By controlling the elasticity and viscosity of robot joints, a robot can work in compliance with external environment. we control the elastic coefficient and the viscous coefficient of joint by adjusting the phase difference of the motor power. And we contemplate transient response of USM with adjusting the elastic coefficient and the viscous coefficient. To use the result, we can control the robot to reach its goal with compliance motion. It remains for further research to develop the impedance control of USM.