• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.2
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• pp.80-86
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• 2001

We design a sliding mode cascade observer to estimate derivatives of the output. In the 1st step of the observer, the output will be estimated, and the 1st order derivative of the output will be estimated via the 2nd step of the observer. Also, nth order derivative of the output will be estimated in the n+1th step of the observer. Exponential convergence of the estimation errors is shown under the bounded initial condition. Numerical examples will be presented to show the validity of the proposed observer.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2212-2214
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• 2003

We design a sliding mode cascade observer to estimate state of the output. In the 1st step of the observer, the output will be estimated, and the 1st order state of the output will be estimated via the 2nd step of the observer. Also, nth order state of the output will be estimated in the n+1th step of the observer. Therefore, this paper will be presented to design the slide mode observer of cascade based cascading convergence concept of state observer error.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2237-2239
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• 2001

Backstepping procedures for output-feedback of nonlinear systems are considered. For these systems, a sliding mode cascade observer to estimate derivatives of the output is builded. In the 1st step of the observer, the output is estimated, and the 1st order derivative of the output is estimated via the 2nd step of the observer. Also, n-th order derivative of the output is estimated in the n+1th step of the observer. Observer errors and tracking errors converge to a residual set close to zero asymptotically.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.2
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• pp.168-173
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• 2009

This paper investigates the estimation problem of vehicle velocity and propeller angular velocity on the underwater vehicle. Inspired by but different from a high-gain observer, the cascade observer features a cascade structure and adaptive observer gains. In doing so the cascade observer attempts to overcome some of the typical problems that may pose to a high-gain observer. As in the case of a high-gain observer, the cascade observer structure is simple and universal in the sense that it is independent of the system dynamics and parameters. A cascade observer is used for the estimation of velocity from measured position. In the 1st step of the observer, the output is estimated, and the 1st order derivative of measured output is estimated via the 2nd step of the observer. Also, nth order derivative of the output is estimated in the (n+1)th step of the observer. It is shown that the proposed observer guarantees globally asymptotical stability. By simulation results, the proposed observer scheme for the estimations of vehicle velocity and propeller angular velocity shows better performance than the scheme based on the existing observer.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1449-1455
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• 2017

The vector control technique using low-resolution Hall-effect sensors has been widely used especially in consumer electronics. Due to electrical and/or mechanical unevenness related to binary-type Hall sensors, the calculated or estimated position information has discontinuities so called bumps, which causes the deterioration of vector control performance. In order to obtain a linearly changing position signal from low-precision Hall-effect sensors, this paper proposes a simple bumps in position signal removal algorithm that consists of a first-order observer with low-pass filtering scheme. The proposed algorithm has the feature of no needs for system parameters and additional estimation processes. The validity of the proposed method is verified through simulation and experimental results.

• Journal of the Korea Safety Management & Science
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• v.14 no.2
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• pp.123-136
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• 2012

The validity of the results from observational methods such as RULA, REBA, OWAS has been one of major concerns due to their subjective characteristics in determining the posture of interests. There have been many studies regarding validity of the results from each checklist. However, most studies provided only fragmentary rather than comprehensive results in nature. This study specifically tried to analyze consistency of novice user based on intra-observer consistency and sensitivity of industrial types during MSDs(Musculoskekltal Disorders) evaluation with major checklists. In this study, twenty two novice subjects were participated to conduct MSDs evaluation for the forty five jobs from three types of industries(automobile, electronics, hospital). The main results for this study were summarized as follows; 1) The action level based on RULA was always higher than that from REBA and OWAS for all three types of industries., 2) The order of consistency from novice users was OWAS(72.7%(kappa=0.57)) RULA(54.3%(kappa=0.41)), REBA(41.0%(kappa=0.34))., 3) The percentage of agreement between 2nd and 3rd trials was higher than those between 1st and 2nd trials and between 1st and 3rd trials irrespective of industrial types during using RULA and REBA., 4) The average score of automobile industry was higher than those of hospital and electronics industries., 5) The types of jobs associated with five body parts(A1(Front), A2(Interior), A3(Rear), A4(Lower), A5(Door)) in automobile industry showed statistically significant differences in terms of MSDs scores for the body parts considered in each checklists.