• Smart Structures and Systems
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• 제16권2호
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• pp.329-345
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• 2015

As commonly known, sensor errors and faulty signals may potentially lead structures in vibration to catastrophic failures. This paper presents a new approach to deal with sensor errors/faults in vibration control of structures by using the Fault detection and isolation (FDI) technique. To demonstrate the effectiveness of the approach, a space truss structure with semi-active devices such as Magneto-Rheological (MR) damper is used as an example. To address the problem, a Linear Matrix Inequality (LMI) based fixed-order $H_{\infty}$ FDI filter is introduced and designed. Modeling errors are treated as uncertainties in the FDI filter design to verify the robustness of the proposed FDI filter. Furthermore, an innovative Fuzzy Fault Tolerant Controller (FFTC) has been developed for this space truss structure model to preserve the pre-specified performance in the presence of sensor errors or faults. Simulation results have demonstrated that the proposed FDI filter is capable of detecting and isolating sensor errors/faults and actuator faults e.g., accelerometers and MR dampers, and the proposed FFTC can maintain the structural vibration suppression in faulty conditions.

• 항공우주기술
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• 제6권2호
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• pp.21-28
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• 2007

본 논문의 목표는 고장허용제어시스템에 대한 기반 연구로서 무인비행기 안전성 향상을 위하여 조종면 작동불능과 같은 고장에 대해 검출 방법을 제시하는 것이다. 조종면 고장검출을 위한 실시간 시스템식별 알고리듬은 퓨리에 변환기법을 사용하였으며 프로그램 성능 및 검증을 위해 HILS 시험과 비행시험을 수행하였다. 엘리베이터 조종면 고장은 피칭모멘트에 대한 조종면 효과를 나타내는 조종미계수를 실시간 추정하여 정상상태의 값과 비교함으로써 검출된다. 비행시험 결과를 통해 고장상태의 조종미계수 값은 정상상태의 값보다 작다는 것을 확인하였다.

• 전자공학회논문지B
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• 제29B권4호
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• pp.22-30
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• 1992

A redundant control scheme which can maintain its tracking capability in the case of a controller failure is proposed for the industrial applications which need high reliability with fault-tolerance. It consists of two identical controllers and a switching mechanism which includes failure detection and reconfiguration algorithm. The new detection method against controller failure using fuzzy logic enables the detection of controller failures without failure assumptions through the instability of the failed controller. The failed controller is smoothly removed from the control loop by reducing time weight of the failed controller.

• 대한기계학회논문집A
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• 제32권3호
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• pp.232-239
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• 2008

The position sensors used in a magnetic bearing system are desirable to provide some degree of fault-tolerance as the rotor position is necessary for the feedback control to overcome the open-loop instability. In this paper, we propose an inductive position sensor that can cope with a partial fault in the sensor. The sensor has multiple poles which can be combined to sense the in-plane motion of the rotor. When a high-frequency voltage signal drives each pole of the sensor, the resulting current in the sensor coil contains information regarding the rotor position. The signal processing circuit of the sensor extracts this position information. In this paper, we used the magnetic circuit model of the sensor that shows the analytical relationship between the sensor output and the rotor motion. The multi-polar structure of the sensor makes it possible to introduce redundancy which can be exploited for fault-tolerant operation. The proposed sensor is applied to a magnetically levitated turbo-molecular vacuum pump. Experimental results validate the fault-tolerance algorithm.

• Advances in aircraft and spacecraft science
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• 제5권4호
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• pp.459-475
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• 2018

In the field of aerospace engineering, accurate control of a spacecraft's orientation is often very important to mission success. Therefore, attitude control is a technically plentiful and extensively studied subject in controls literature during recent decades. This investigation of spacecraft attitude control is assumed to address two important aspects of the problem solutions. One sliding mode anti-disturbance control for utilization of faulty actuator components and another one disturbance observer based control to improve the pointing accuracy in the absence of anti-vibration equipment for the elastic appendages like a solar panel. Simultaneous occurrence of vibration due to flexible appendages and reaction degradation due to failure in attitude actuators complicates this case. The advantage of this method is acquisition proper control by the combination of disturbance observer and sliding mode compensation that form a fault tolerant control for the concerned satellite attitude control system. Furthermore, the proposed composite method indicates that occurrence the failure in actuators and even elastic solar panel vibration effect may be handled directly without reconfiguring the control components or providing piezoelectric devices. It's noteworthy, attitude quaternion and angular velocity commands are robustly tracked via controllers to become inclined to zero.

• 한국산업융합학회 논문집
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• 제26권2_1호
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• pp.231-238
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• 2023

This paper develops the theory for a novel fault-tolerant, permanent magnet biased, 6-active-pole, homopolar magnetic bearing. The Lagrange Multiplier optimization with equality constraints is utilized to calculate the optimal distribution matrices for the failed bearing. some numerical examples of distribution matrices are provided to illustrate the new theory. Simulations show that very much the same dynamic responses (orbits or displacements) are maintained throughout failure events (up to any combination of 3 coils failed for the 6 pole magnetic bearing) while currents and fluxes change significantly. The overall load capacity of the bearing actuator is reduced as coils fail. The same magnetic forces are then preserved up to the load capacity of the failed bearing.

• 한국군사과학기술학회지
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• 제16권3호
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• pp.240-249
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• 2013

This paper discusses the maneuvering control algorithm based on all-wheel independent driving and steering control techniques for special purpose 6WD/WS vehicles. The maneuvering control algorithms considering superior dynamic characteristics of high power in-wheel motors and independent steering system are designed to perform driving, steering, vehicle stability, and fault tolerant control. The maneuvering controller applies sliding and optimal control theories considering optimal torque distribution and friction circle related to the vertical tire force. The fault tolerant control algorithm is applied to obtain the similar maneuverability to that of the non-faulty vehicle. The simulations using the Matlab/Simulink dynamics model and experiments using HIL simulator mounting the real controllers with the designed control algorithms prove the improved performances in terms of vehicle stability and maneuverability.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1263-1266
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• 1997

In a fault-tolerant modern manufacturing systms characterized by the configuration, in which automated redundant machines prone to unexpected failures are interconnected with other complex subsystems such as AGV's, robots, computer control systems to produce complete parts, faulures together with repairs and reconfigurations should be considered as the three basic events to be modeled for computing the performance of manufacturing systems. In this papre, transient analysis is applied to modular cell manufacturing systems form a performability viewpoint whose modeling adantage is that various performanc e measures can be evaluated compositely in the context of application. The hypothertical modular cells are modeled firstly with hybrid decomposition method and availability measures as special cases of performability are computed and comments on performabililty modeling analysis are mentioned.

• 한국통신학회논문지
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• 제21권8호
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• pp.1989-2002
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• 1996

In this paper, we describe several warm standby fault-tolerant models and their operation methods applicable to telephone switching control systems which have dual module structure and need high availability. Unavailabilities of the system implemented by four different methods for each model are computed by using the Markov state model, and then are compared for system performance evaluation. As the results ofsimulations, the warm standby model with triple processors is best in the aspect of data loss, while in most cases the warm standby model with doble processors based on no standby check method provides the highest system avaiability. Periodic changeover increases the system unavailability, but the preriodic standby check on standby module decreases the system unavailability of warm standby model with a single processor and with double processors. On the other hands, the variationas of warm standby model with a single processor and with double processors. On the other hand, the variations of data recovery time and personnel recovery rate have little effect on the system unavailtability.

• 한국통신학회논문지
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• 제34권11B호
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• pp.1133-1141
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• 2009

본 논문에서는 무선 센서 망으로 k-연결 (k+1)-감지 고장 감내 위상을 구성하는 분산 위상 제어 프로토콜을 제시한다. 센서 망에 있어 최근에 주목받고 있는 근본적인 문제는 최소한의 활동하는 노드들로 위상을 구성하며, 다양한 응용과 환경에 적합한 감지도와 망 연결수를 제공하는 것이다. 망의 수용 능력을 증대시키는 동시에 에너지 효율성을 개선하고 더불어 망의 연결성을 유지하기 위해서, 많은 위상 제어 알고리즘들이 제안되어 왔다. 대부분의 알고리즘들은 연결되는 링크들의 수를 줄임으로써, 노드들의 고장이나 파손시에 여분의 경로배정이 어렵게 되는 문제를 발생시킨다. 특정 감지도를 보장하며 이 문제를 해결하는 프로토콜이 제안되었으나, 감지도 계산을 위해서는 정확한 위치정보가 필요하고, k-감지인 경우에 대부분의 활동 센서들이 2k-연결을 유지한다. 우리는 감지범위의 반지름이 통신 범위의 반지름의 두 배인 조건이 연결이 감지범위를 함의하기 위한 필요충분조건임을 증명하고, 이에 기반하여 무선 센서 망에서 k-연결을 제공하며 (k+1)-감지를 보장하는 고장 감내 위상을 구성하는 프로토콜을 제시한다. 제안한 분산된 알고리즘은 정확한 위치정보 없이 (k+1)-감지를 보장하며, 복잡도는 O(1) 이다. 모의 실험하여 패킷손실율과 전송 지연시간 그리고 에너지 소비율을 분석 하였다.