• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.287-290
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• 1996

Fault diagnosis problem is currently the subject of extensive research and numerous survey paper can be found. Although several works are studied on the fault detection and isolation observers and the residual generators, those are concerned with only the detection of actuator failures or sensor failures. So, the perfect detection and isolation is strongly required for practical applications. In this paper, a, strategy of fault diagnosis using multiple proportional integral (PI) observers including the magnitude of actuator failures is provided. It is shown that actuator failures are detected and isolated perfectly by monitoring the integrated error between actual output and estimated output by a PI observer. Also in presence of complex actuator and sensor failures, these failures are detected and isolated by multiple PI observers.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.483-487
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• 1996

We consider the estimation of the position and orientation of 6 DOF motion bed (Stewart platform) from the measured cylinder length. The solution of forward kinematics is not solved yet as a useful realtime application tool because of the complity of the equation with multiple solutiple solutions. Hence we suggest an algorithm for the estimation of forward kinematics solution using Luenberger observer withnonlinear error correction term. The Luenberger observer withlinear model shows that the estimation error does not go to zero in steadystate due to the linearization error of the dynamic model. Hence the linear observer is modified using nonlinear measurement error equation and we prove thd practical stability of the estimation error dynamics of the proposed observer using lyapunov function.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.127-135
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• 2021

The goal of this study was to explore the use of multiple SNS platforms and determine whether the number of used platforms affects one's online self-presentations across the said platforms and if there is any difference in one's online and offline self-presentations based on how many SNS platforms are used. This work studied online self-presentations, compared the on/offline ones and tried to find out if the inconsistencies of one's own (observer's) self-presentations both online (across platforms) and on/offline affected the observer's impression formation (likability, trustworthiness and hypocrisy) of others. The study also aimed to find out if the impression of the others' inconsistency both online and offline would differ based on the level of intimacy between the observer and the discussant. Three levels of intimacy were studied in order to do this: friends, acquaintances and strangers (online-only friends). The results showed that the more platforms people used the more inconsistent their online self-presentations got. Even though the results of the study showed barely significant relationship between the number of SNS accounts and one's online and offline self-presentation, and partial connection between observer's inconsistent self-presentations and impression formation of others, interestingly enough, the results managed to find significant differences between the impressions based on the level of intimacy between the observer and the discussants.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.3
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• pp.281-292
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• 2014

We propose a novel cooperative guidance law design method based on the finite time disturbance observer (FTDO) for multiple near space interceptors (NSIs) with impact time control. Initially, we construct a cooperative guidance model with head pursuit, and employ the FTDO to estimate the system disturbance caused by target maneuvering. We subsequently separate the cooperative guidance process into two stages, and develop the normal acceleration command based on the super-twisting algorithm (STA) and disturbance estimated value, to ensure the convergence of the relative distance. Then, we also design the acceleration command along the line-of-sight (LOS), based on the nonsingular fast terminal sliding mode (NFTSM) control, to ensure that all the NSIs simultaneously hit the target. Furthermore, we prove the stability of the closed-loop guidance system, based on the Lyapunov theory. Finally, our simulation results of a three-to-one interception scenario show that the proposed cooperative guidance scheme makes all the NSIs hit the target at the same time.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2230-2232
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• 2004

A residual generation scheme that can be employed in the process fault detection and isolation systems for a class of nonlinear (control) systems is suggested. Although the scheme is a kind of observer scheme, the design of the observers employed for residual generation is very simple and the order of the observer is very low. In spite of the simplicity, the residual generation scheme provides the same information for the detection and isolation of the anticipated faults as the conventional multiple observer based schemes. The residuals may be structured so that fault isolation can be performed by pre-selected logic. An FDIS using the residual generation scheme is constructed and evaluated for a nonlinear DC motor system.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.6
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• pp.241-251
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• 2002

The effect of sensor faults in direct torque control(DTC) based induction motor drives is analyzed and a new Instrument fault detection isolation scheme(IFDIS) is proposed. The proposed IFDIS, which operated in real-time, detects and isolates the incipient fault(s) of speed sensor and current sensors that provide the feedback information. The scheme consists of an adaptive gain scheduling observer as a residual generator and a special sequential test logic unit. The observer provides not only the estimate of stator flux, a key variable in DTC system, but also the estimates of stator current and rotor speed that are useful for fault detection. With the test logic, the IFDIS has the functionality of fault isolation that only multiple estimator based IFDIS schemes can have. Simulation results for various type of sensor faults show the detection and isolation performance of the IFDIS and the applicability of this scheme to fault tolerant control system design.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1196-1198
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• 2000

In this paper, a new approach for digital feedback control of PWM inverter is proposed, in which an output DB(Dead-Beat) control is achieved combined with a simple disturbance observer. The deadbeat controller, which is constructed multiple loop control scheme for PWM inverter, is used for fast transient response. The disturbance observer can make the disturbances be cancelled by adding feedforward compensating loop in controller. The simulation result show the proposed control scheme can achieved good voltage regulation against large load variations.

• IEMEK Journal of Embedded Systems and Applications
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• v.19 no.3
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• pp.123-130
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• 2024

This paper proposes an EMPC (Explicit Model Predictive Controller) for temperature tracking control based on heat load prediction by an ESO (Extended State Observer) for a variable cooling circulation system with multiple indoor units connected to one outdoor unit. In this system, heat transfer and heat loss relative to the input temperature are modeled using system dynamics. Using this model, we design an EMPC based on an ESO that is robust to temperature changes and depends on airflow. To determine the stability of both the controller and the observer, asymptotic stability is verified through Lyapunov stability analysis. Finally, to validate the performance of the proposed controller, simulations are conducted under three scenarios with varying airflow, set temperature, and heat load.

• Korean Journal of Radiology
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• v.25 no.4
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• pp.325-327
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• 2024

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.05a
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• pp.437-441
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• 1999

In this paper, a fault diagnosis method using unknown-input proportional integral (PI) observers including the magnitude of actuator failures is proposed. It is shown that actuator failures are detected and isolated perfectly by monitoring the integrated error between the actual output and the estimated output using an unknown-input PI observer. Also in presence of complex actuator and sensor failures, these failures are detected and isolated by multiple unknown-input PI observers perfectly.