Post on 02-Jan-2016
description
Humble HubbleTeam 18 – Derek Pesyna
AbstractThe proposed project is a self-aiming
telescope. This telescope will obtain its global position and the local time via GPS. It will then automatically orient
itself to point at a user selected target (star) using a variety of onboard sensors.
Background: http://apod.nasa.gov/apod/image/1302/ngc1763_lake_1600.jpg
Definition of Criticality Levels
• λ - the predicted number of failures per 106 hours of operation • High: Injury to user and critical system failure (
10-9 )• Medium: Whole system needs
replaced/repaired ( 10-6 )• Low: PCB/single component can be easily
repaired ( 10-5 )
FMECA Chart
Failure No.
Failure Mode Possible Causes Failure Effects Method of Detection
Criticality Remarks
A1 Motor Output @ 100% (full on)
-H-Bridge Failure -Micro motor output stuck high
Telescope moves unexpectedly & continues moving
Observation Medium Worse case: telescope mount breaks
B1 Telescope does NOT point north and is NOT level during calibration
-Compass failure-Accel. Failure-Gyro Failure-Encoder Failure
Compass cannot be calibrated and thus will not function
Observation Low Component replaced on breakout module and/or sensor breakout PCB replaced
B2 Telescope does not point to correct celestial body
-Compass failure-Accel. Failure-Gyro Failure-Encoder Failure
Compass is not functional (manual control may be necessary)
Observation Low
C1 Telescope does not move
-269 Vex Motor Failure-Power supply not functional-Micro fried
Compass not functional
Observation Low/Medium