• Journal of Mechanical Science and Technology
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• 제18권7호
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• pp.1131-1139
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• 2004

A new impedance controller is proposed for bilateral teleoperation under a time delay. The proposed controller does not need to measure or estimate the time delay in the communication channel using the force loop-back. In designing a stable impedance controller, absolute stability is used as a stability analysis tool, which results in a less conservative controller than the passivity concept. Moreover, in order to remove the conservatism associated with the assumption of infinite port impedances, the boundaries of human and environment impedance are set to finite values. Based on this, this paper proposes a parameter design procedure for stable impedance controllers. The validity of the proposed control scheme is demonstrated by experiments with a 1-dof master/slave system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.333-335
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• 2006

This paper presents a force-reflecting teleoperation scheme with time delay. In reciprocal systems, to improve the stability and performance of the tleleoperation system, the network provides a wide bandwidth, no congestion. However, as use of Internet increases, congestion situation of network increased and transmission time and packet loss increased accordingly. This can make system unstable at remote control. In this paper, we present a passive control scheme for a force reflecting bilateral teleoperation system via the Internet and we investigated how a varying time delay affects the stability of a teleoperation system. A new approach based on a passive control scheme was designed for the system. The simulation results and the tracking performance of the implemented system are presented in this paper.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.122-124
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• 2007

Master and slave of teleoperation control system through internet or long distance cable must keep stable. If one part becomes unstable or time delay happens in network, the all system can become unstable. Usually stability of teleoperation control system can distinguish by passivity. In this paper, we implemented bilateral teleopcration control system that load passivity controller to keep stability of system. Composed by manipulator that trillion this sricks and horizontal manufacturing that have force reflecting function are available and embodied so that control through wireless LAN may be available. And distinguished stability through an experiment and manufacturing performance.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.32.5-32
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• 2001

There has been many teleoperation systems handling the micro object. However, the stability problem for these systems has not been mentioned yet. Historically, Lawrence[1] proposed the Transparency-Optimized Architecture and passivity theorem for stability analysis of bilateral teleoperation. He claimed that unless the task(or environment) impedance contains significance inertial behavior, Passivity condition for Transparency-optimized architecture is not satisfied. In this paper we propose one method which satisfies passivity condition for the micro-teleoperation system handling a insignificant inertial object and is based on the structure of Lawrence and Hashtrudi-Zaad[2] and velocity-force scaling.

• 전자공학회논문지SC
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• 제46권1호
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• pp.22-27
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• 2009

인터넷과 같은 네트워크 시스템에서 네트워크 혼잡, 대역폭, 거리에 따라 발생하는 시변 시간지연을 해결하는 것은 양방향 원격제어 시스템을 설계할 때 해결해야할 문제이다. 불규칙적인 시간 지연은 전체 시스템의 성능을 저하시키거나 불안정하게 만들 수 있기 때문이다. 이러한 안정성 문제를 해결하기 위해 양방향 원격 제어 시스템에서 수동성 이론이 사용되어져 왔다. 본 논문에서는 시간 지연의 변화율에 따라 전송 제어기에 시변 이득을 적용하여 수동성을 확보할 수 있는 알고리즘을 제안하였다. 그리고 시뮬레이션을 통해 제안한 시스템의 성능 결과를 보였다.

• 제어로봇시스템학회지
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• 제17권2호
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• pp.27-35
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• 2011

This paper presents the state of the art of control strategies for bilateral teleoperation systems under time delays. In the bilateral teleoperation that has force feedback, the time delay in the communication channel is the main source of instability. To cope with this problem. a number of control methods have been proposed. Among many control strategies. key aspects of the recent passivity-based methods are mainly summarized for approaches with wave variables. PO/PC (passivity observer/passivity controller), simple PD, and energy bounds.

• 제어로봇시스템학회논문지
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• 제6권4호
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• pp.295-304
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• 2000

In the teleoperation system, force and velocity signals are communicated between a master and a slave robot. The addition of force feedback to a teleoperation system benefits the operator by providing more information to perform given tasks especially for tasks requiring contact with environment. When the master and slave arms are located in different places, time delay is unavoidable and it is well known that the system can become unstable when even a small time delay exists in the communication channel. The control scheme proposed in this paper is based on the estimator with virtual master model. Delayed signal from the master robot can be replaced by the estimated signal with the virtual master model. This control scheme makes the teleoperation system stable for the given time delay while the conventional scheme is not. This new control scheme is verified through numerical simulations and an experiments using the dual axis testbed of the teleoperation system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.336-341
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• 2004

In this paper, a hybrid stabilization approach involving both passivity observer/passivity controller and wave variables is addressed to stabilize a teleoperation system with fixed time delay. To guarantee the stability of master or slave side, passivity observer/passivity controller are applied. But, passivity observer/passivity controller cannot deal with communication delay, and thus even small communication delay cause the system to be unstable. To cope with this problem, wave variables are additionally employed to have robustness to fixed communication delays. To show the validity of our proposed approach, several computer simulation results are illustrated.

• 대한기계학회논문집A
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• 제27권11호
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• pp.1967-1978
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• 2003

Transparency has been considered as a performance measure in bilateral teleoperation system. Therefore, many issues of transparency have been studied. This paper investigates the transparency in two-channel control architectures. At first, we show the feasibility using analytic transparency-conditions and present the two classes of two-channel control architecture, which are perfectly transparent under ideal situation. In addition, remedies to problems due to impedance model estimation errors under real situation are introduced. They are as fellows; design guideline of control parameters to reduce the effect of model estimation error effect and introduction of time delay estimation for unknown dynamics. From these analyses, the systematic control scheme, which is stable and well transparent under real implementation, is proposed in two-channel control architecture. Finally, the proposed scheme is applied to a 2 D.O.F master-slave system and the experimental results show the validity of the theoretical work.

• Transactions on Control, Automation and Systems Engineering
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• 제4권1호
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• pp.100-107
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• 2002

The advanced bilateral control algorithm, which can enlarge a reflected force by combining force reflection and compliance control, greatly enhances workability in teleoperation. In this scheme the maximum boundaries of a compliance controller and a force reflection gain guaranteeing stability and good task performance greatly depend upon characteristics of a slave arm, a master arm, and an environment. These characteristics, however, are generally unknown in teleoperation. It is, therefore, very difficult to determine such maximum boundary of the gain. The paper presented a novel method for design of an advanced bilateral controller. The factors affecting task performance and stability in the advanced bilateral controller were analyzed and a design guideline was presented. The neurofuzzy compliance model (NFCM)-based bilateral control proposed herein is an algorithm designed to automatically determine the suitable compliance for a given task or environment. The NFCM, composed of a fuzzy logic controller (FLC) and a rule-learning mechanism, is used as a compliance controller. The FLC generates compliant motions according to contact forces. The rule-learning mechanism, which is based upon the reinforcement learning algorithm, trains the rule-base of the FLC until the given task is done successfully. Since the scheme allows the use of large force reflection gain, it can assure good task performance. Moreover, the scheme does not require any priori knowledge on a slave arm dynamics, a slave arm controller and an environment, and thus, it can be easily applied to the control of any telerobot systems. Through a series of experiments effectiveness of the proposed algorithm has been verified.