Performance characterization Don clausing C Don Clausing 1998 16881 Fig. 1
Performance characterization Don Clausing © Don Clausing 1998 16.881 Fig. 1
Failure modes Noises lead to failure modes (Fm) One set of noise values leads to fm Opposite set of noise values leads to FM, Simple problem solving chases the problem from Fm, to Fm, and back again, but does not avoid both fms with the same set of design values-endless cycles of build/test/fix (B/T/F) C Don Clausing 1998 16881 Fig 2
Failure modes • Noises lead to failure modes (FM) • One set of noise values leads to FM1 • Opposite set of noise values leads to FM2 • Simple problem solving chases the problem from FM1 to FM2 and back again, but does not avoid both FMs with the same set of design values – endless cycles of build/test/fix (B/T/F) © Don Clausing 1998 16.881 Fig. 2
Failure modes occurrence Failure modes occur when the essential performance characteristic deviates excessively from its ideal value Some failure modes are simply values that deviate so far that output is not useful; e.g voltage from power supply is too low Some failure modes are catastrophic; e.g paper that arrives too soon jams in copier C Don Clausing 1998 16881 Fig. 3
Failure modes occurrence • Failure modes occur when the essential performance characteristic deviates excessively from its ideal value • Some failure modes are simply values that deviate so far that output is not useful; e.g., voltage from power supply is too low • Some failure modes are catastrophic; e.g., paper that arrives too soon jams in copier © Don Clausing 1998 16.881 Fig. 3
Performance characteristic What is good performance characteristic to use when reducing the occurrence of failure modes? Dont merely count occurrence of failure modes Can't distinguish between following two cases C Don Clausing 1998 16881 Fig 4
Performance characteristic • What is good performance characteristic to use when reducing the occurrence of failure modes? • Don’t merely count occurrence of failure modes • Can’t distinguish between following two cases © Don Clausing 1998 16.881 Fig. 4
Case 1 -easy to fix Occurrence of failure mode FM FM C Don Clausing 1998 16881 Fig 5
Case 1 – easy to fix Occurrence of failure mode FM1 FM2 © Don Clausing 1998 16.881 Fig. 5