• Journal of Internet Computing and Services
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• v.12 no.2
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• pp.47-53
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• 2011

When some sensors under Wireless Sensor Networks fail or become energy-exhausted, redundant mobile sensors might be moved to recover the sensing holes. Within rugged terrain where wheeled sensors are unsuitable, other type of mobile sensors, such as hopping sensors, are needed. In this paper, we address the problem of relocating hopping sensors to the detected sensing holes. Recent study for this work considered the relocation using the shortest path between clusters; however, the shortest path might be used repeatedly and create other sensing holes. In order to overcome the mentioned problem, we propose relocation schemes using the most disjointed paths or multi-paths. Simulation results show that the proposed schemes guarantee more balanced migration distributions of efficient sensors and higher movement success ratios of required sensors than those of the shortest path-based scheme.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.32.4-32
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• 2002

We consider inertial navigation system (INS) sensor redundancy and propose a method which uses singular value decomposition to detect and isolate faults when even two sensors have faults simultaneously. When redundant sensor configuration is given, such as symmetric configuration in INS, the range space and null space of configuration matrix are determined. We use null space of configuration matrix and define 21 reference fault vectors which include 6 one-fault vectors and 15 two-fault vectors. Measurements are projected into null space of measurement matrix and compared with 21 normalized reference fault vectors, which determines fault detection and isolation.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.792-796
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• 1992

Readings from robotic sensors are somewhat uncertain. This uncertainty problem makes it difficult to employ the sensor feedback controlled robots widely in real industrial sites, In this paper, redundant sensor fusion techniques are discussed to effectively overcome the sensor uncertainty, A weighted averaging technique is proposed under static and dynamic sensing environments. Proposed technique is tested by the experiments of stereoscopic 3d position measurements.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.321-325
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• 2001

Servo drives with microcomputer control provide the possibility of using modem and sophisticated control algorithms. As an additional feature it is possible to implement parallel and/or redundant software and hardware structures to realise safe motion or similar security functions. Unfortunately microcomputer control also has some impact on the behaviour of servo drives. Control algorithm, cycle time, sensors and interface have to be perfectly synchronised. Special control schemes are necessary on the line side (power supply) to meet the actual requirements concerning EMC. This contribution presents experiences and results obtained from a modem digital drive system pointing out the influences of low and high accuracy position sensors and the interdependencies mentioned above.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.321-328
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• 1998

A controller and sensor fault tolerant system jot a steam generator is designed with fuzzy logic. A structure of the : proposed fault tolerant redundant system is composed of a supervisor and two fuzzy weighting modulators. A supervisor alternatively checks a controlled and a sensor induced performances to identify Which Part, a controller or a sensor, is faulty. In order to analyze controller induced performance both an error and a charge in error of the system output an chosen as fuzzy variables. The fuzzy logic jot a sensor induced performance uses two variables : a deviation between two sensor outputs and its frequency, Fuzzy weighting modulator generates an output signal compensated for faulty input signal. Simulations show that the : proposed fault tolerant control scheme jot a steam generator regulates welt water level by suppressing fault effect of either controllers or sensors. Therefore through duplicating sensors and controllers with the proposed fault tolerant scheme, both a reliability of a steam generator control and sensor system and that of a power plant increase even mote.

• Journal of the Korea Society of Computer and Information
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• v.21 no.2
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• pp.25-32
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• 2016

In this paper, we design a middleware for context-awareness which provides compound contexts from diverse sensors on a mobile device. Until now, most of context-aware application developers have taken responsibility for context processing from sensing data. Such application-level context processing causes heavily redundant data processing and leads to significant resource waste in energy as well as computing. In the proposed scheme, we define primitive and compound context map which consists of relavant sensors and features. Based on the context definition, each application demands a context of interest to the middleware, and thus similar context-aware applications inherently share context information and procesing within the middleware. We show that the proposed scheme significantly reduces the resource amounts of cpu, memory, and battery, and that the performance gain gets much more when multiple applications which need similar contexts are running.

• Journal of Power Electronics
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• v.2 no.1
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• pp.25-31
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• 2002

Servo drives with microcomputer control provide the possibility of using modern and sophisticated control algorithms. As an additional feature it is possible to implement parallel and/or redundant software and hardware structures to realise safe motion or similar security functions. Unfortunately microcomputer control also has some impact on the behaviour of servo drives. Control algorithm, cycle time, sensors and interface have to be perfectly synchronised. Special control schemes are necessary on the line side (power supply) to meet the actual requirements concerning EMC. This contribution presents experiences and results obtained from a modern digital drive system pointing out the influences of low and high accuracy position sensors and the interdependencies mentioned above.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1993.06a
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• pp.1001-1004
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• 1993

The Multisensor Fusion Problem (MFP) deals with the methodologies involved in effectively combining together homogeneous or non-homegeneous information obtained from multiple redundant or disparate sensors in order to perform a task more accurately, efficiently, and reliably. The inherent uncertainties in the sensory information are represented using Fuzzy Numbers, -numbers, and the Uncertainty-Reductive Fusion Technique (URFT) is introduced to combine the multiple sensory information into one consensus -number. The MFP is formulated from the Information Theory perspective where sensors are viewed as information sources with a fixed output alphabet and systems are modeled as a network of information processing and processing and propagating channels. The performance of the URFT is compared with other fusion techniques in solving the 3-Sensor Problem.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.113-118
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• 2005

Robots today have wider application fields than they ever have before. They need to work close to humans and fluid and compliable motions are expected of them. This requires redundant degrees of freedom for completing specific task. And conventional motion teaching method cannot be applied to redundant link structures. In this paper, the authors present a proficient, cost-effective and intuitive method for motion teaching. New software to apply this method to a humanoid is also presented. This new method utilizes current sensors to determine which joints to rotate. The experiment shown in this paper is a case of closed link where arms cannot move independently due to the restrictions in between the hands. After the input of several passing points of motion trajectory, the curve fitting is performed by the developed software. This software can insert new points, delete erroneous points and modify existing points. The developed motion teaching method is applied to the Kumdo robot, which is developed by the authors.

• Proceedings of the KIEE Conference
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• 2008.04a
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• pp.199-200
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• 2008

Demand for reliability and safety in modem systems has been increased in the research on fault detection and isolation. At traditional approaches to fault detection, redundant sensors have been used. More advanced methods are the residual analysis of signals which are created by the comparison between the actual plant behavior and the output response of a mathematical model. However, mathematical system models are difficult to obtain by using physical laws. These problems can be solved by system identification. In this paper, the transfer function of a direct current motor is estimated by using the system identification. And, the efficiency of the fault detector design is verified by using experiments.