Page 29 - Sayı-08

RISK ASSESSMENT OF UNDERWATER GLIDERS USING 27
UNCERTAINTY ANALYSIS AND FAULT TOLERANT CONTROL

Detection Table 4: Detection Table Ranking
Absolute Likelihood of Detection by Design
uncertainty 10
Very remote Cannot detect
Remote 9
Very low Very remote chance of detection 8
Low Remote chance of detection 7
Moderate Very low chance of detection 6
Moderate high Low chance of detection 5
High Moderate chance of detection 4
Very high Moderately high chance of detection 3
Almost certain High chance of detection 2
Very high chance of detection 1
Design control will detect the failure

The possible failure modes in the navigation system are determined in sub-system basis. In the
ballast mechanism there are ballast pump, tank and coupler parts. Main control unit is made of
mother board. Pitch Motion system has pitch motor, shaft and coupler. Roll motion system is
made of servo and a coupler. Energy unit has batteries and cables. Antenna is a part of
communication system. Pressure sensor, altimeter, gyro and collision sensor are parts of sensory
unit. Lastly, wings are included under hull sections. When all of those sub-systems are
investigated the most possible failure types can be understood and the effect of the failure can be
derived from there using experience or computer simulation methods. If we group all the
information for FMEA in a table, Table 5 appears.

Figure 4. A generic underwater glider with sections used in navigation

Sayı 8, 2017 GiDB|DERGi