• International Journal of Control, Automation, and Systems
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• 제5권1호
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• pp.1-7
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• 2007

In this paper, the necessary and sufficient conditions for strict positive realness of the rational transfer functions directly from basic definitions in the frequency domain are studied. A new frequency domain approach is used to check if a rational transfer function is a strictly positive real or not. This approach is based on the Taylor expansion and the Maximum Modulus Principle which are the fundamental tools in the complex functions analysis. Four related common statements in the strict positive realness literature which is appeared in the control theory are discussed. The drawback of these common statements is analyzed through some counter examples. Moreover a new necessary condition for strict positive realness is obtained from high frequency behavior of the Nyquist diagram of the transfer function. Finally a more simplified and completed conditions for strict positive realness of single-input single-output linear time-invariant systems are presented based on the complex functions analysis approach.

• International Journal of Control, Automation, and Systems
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• 제3권2호
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• pp.195-201
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• 2005

This paper discusses the problem of positive real control for uncertain 2-D linear discrete time singular Roesser models (2-D SRM) with time-invariant norm-bounded parameter uncertainty. The purpose of this study is to design a state feedback controller such that the resulting closed-loop system is acceptable, jump modes free and stable, and achieves the extended strictly positive realness for all admissible uncertainties. A version of positive real lemma for the 2-D SRM is given in terms of linear matrix inequalities (LMIs). Based on the lemma, a sufficient condition for the solvability of the positive real control problem is derived in terms of bilinear matrix inequalities (BMIs) and an iterative procedure for solving the BMIs is proposed.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1424-1429
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• 2003

In this paper, the design method of sliding mode control (SMC) system for SISO linear system is discussed. First, we consider the similarity between the design method of sliding mode hyper plane using the strict positive realness and the characteristics of zeros of feedback system and the design method of simple adaptive control. Based on such a consideration, we propose the new design method of SMC system using parallel dynamic compensator. As a result, SMC system can be constructed only with the derivative of output signal for controlled plant. The performance of SMC system designed by proposed method is confirmed through the numerical example.

• 제어로봇시스템학회논문지
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• 제4권5호
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• pp.574-578
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• 1998

This paper considers the robust positive real problem for linear systems with linear fractional-type norm-bounded repeated scalar block parameter uncertainty. It is shown that the robust positive real problem can be converted into the standard positive real problem without uncertainty that can be used for the analysis of the given uncertain linear system and the synthesis of a controller that robustly stabilizes and achieves the extended strict positive realness property of the closed-loop transfer function. These results can be also applied to the linear system with general structured uncertainty containing repeated scalar block parameters and are extensions of the previous works that consider only norm-boundedness of the affine unstructured uncertainty.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1999년도 제14차 학술회의논문집
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• pp.1-4
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• 1999

This paper presents a design scheme of robust parallel compensator for plants with multiple uncertainty, which realizes strict positive realness of the closed-loop system by using static output feedback. Further, an ap-proximate relation between the static output feedback control system with the proposed compensator and the PID$.$‥D$\^$r-1 control system is shown.

• 한국교육학연구
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• 제23권1호
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• pp.35-56
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• 2017

이 연구는 가상현실 학습공간에서 동작인식 인터페이스의 적용효과를 검증하기 위한 것이다. 동작인식 인터페이스는 사용자의 동작을 인식해서 작동하는 방식이므로 기존의 인터페이스와는 달리 신체적인 움직임을 자연스럽게 표현한다는 장점을 갖고 있다. 이러한 특징 때문에 동작인식 인터페이스가 가상현실과 같은 실감형 학습환경에서 실제로 긍정적인 효과를 나타내는지 검증하기 위하여 이 연구가 수행되었다. 특히, 동작기반 인터페이스가 가상현실 학습공간의 실감형 디스플레이와 함께 사용될 때 어떤 영향을 미치는지를 검증하였다. 이 연구를 44명의 대학생이 참여했으며 디스플레이의 실감성 수준(착용형 vs. 모니터)과 동작기반 인터페이스의 적용여부(동작기반 vs. 조이스틱)에 따른 적용효과를 검증했다. 연구결과에 따르면 공간구조가 적용되지 않은 학습내용에서는 동작기반 인터페이스가 긍정적인 영향을 미치는 것으로 나타났다. 반면에 공간구조가 적용된 학습내용에서는 조이스틱을 활용하는 것이 더 효과적이었다. 또한 착용형 디스플레이와 같이 실감성이 높은 매체와 함께 동작기반 인터페이스를 함께 활용한다고 하더라도 실감성을 더 높이지 않는 것으로 나타났다. 이 연구에서는 동작기반 인터페이스의 장점과 가상현실 학습공간에서 어떻게 활용될 수 있을 것인지에 대해서 논의하였다.