An adaptive filter based fault detector applied to dynamic positioning system.pdf

FA5 - 12% AN ADAPTIVE FILTER BASED FAULT DETECTOR APPLIED M DYNAMIC POSITIONING SYSTEM J. Selkainaho and A . Halme Helsinki University of Technology, Laboratory of Automation Technology Otakaari 5 A, SF-02150 ESPOO, Finland Summary The paper introduces a fault detection method based on adaptive filtering of the sensor/actuator signals and shows how it has been applied in the simulated dynamic positioning system of a ship. Detection of faults is done by observing changes of statistical parameters in the innovation signals of the filter. Localization is based on a rule logic which takes into account the specific features of the physical system. Faults both in the sensor and actuator components can be detected and localized. The actuators form the thruster system of the ship which maintain controlability in the case one of the thruster faults. It is also demonstrated in the paper how post fault situation can be handled by making a proper change in the control policy. Introduction The main purpose of the dynamic positioning system is to keep the ship in a specified position by proper ac- tion of the propuhion system. Secure functioning of the system is very critical because considerable mate- rial, economic or even personal damages can easily happen if it fails. The idea of dynamic positioning is based on accurate position measurements made by local instruments like acoustic or taut wire sensors and a control system which compensates the drift effects caused by wind, waves, and sea currents. In addition to the position the ship course is measured by a gyro- compass. The faults which cause the system to fail can most probably happen either in the measurement or in the thruster part of the system. The computer which