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Q uantitative E valuation of E mbedded S ystems. Dataflow and Max-Plus Algebra. Exercise: Model a car manufacturing line. Consider a car manufacturing line consisting of. Four assembly robots: A,B,C and D A production unit that needs 20 minutes to produce a chassis
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Quantitative Evaluation of Embedded Systems Dataflow and Max-Plus Algebra
Exercise: Model a car manufacturing line Consider a car manufacturing line consisting of... • Four assembly robots: A,B,C and D • A production unit that needs 20 minutes to produce a chassis • A production unit that needs 10 minutes to produce a steering installation • A production unit that needs 10 minutes to produce a breaking system • A production unit that needs 20 minutes to produce a body • Three painting units that each need 30 minutes to paint a body • A production unit that needs 15 minutes to produce a radio • Robot A compiles the chassis and the steering installation in 4 min. and sends it to B • Robot B adds the breaking system in 3 min. and sends it to C • Robot C adds a painted body in 5 min. and sends it to D • Robot D adds a radio in 1 min. and sends the car out of the factory • For safety reasons, there can be at most 3 ‘cars’ between A and C, and only 2 between B and D • Every robot can only deal with one of each of the assembled components at a time
Answer: Model a car manufacturing line Exercise: calculate the first 3 firings of each actor 30min 20min 10min A B D C 5min 3min 4min 1min 15min Disclaimer: no actual car assembly line was studied in order to make this model. 20min 20min 10min
The algebraic approach: Measuring traffic 30min 20min 10min 5min 3min 4min 1min 15min 20min 20min 10min
Counters v.s. Loggers Tokens Tokens Tokens Counting tokens Logging events Time (s) Time (s) Time (s)
Logging traffic A B C x2 y u x1 x3 15ms 10ms x5 x4 25ms
Logging traffic A B C x2 y u x1 x3 15ms 10ms x5 x4 25ms
Logging traffic A B C x2 y u 15ms 10ms x4 x’4 25ms
Matrix equations A B C x2 y u 15ms 10ms x4 x’4 25ms
Matrix equations A B C x2 y u 15ms 10ms x4 x’4 25ms
Matrix equations A B C x2 The entries in a (max,+) algebra matrix represent the longest* token-free pathsfrom one initial token to another. * Where ‘longest’ is means ‘greatest total execution time’. y u 15ms 10ms x4 x’4 25ms
Exercise: Determine the matrix equations y D C E B A F u 0 ms 1 ms 5 ms 7 ms 2 ms 15 ms
y u 0 ms 1 ms 5 ms 2 7 ms D C E B A F 2 ms 15 ms 3