robin Posted January 19, 2022 Share Posted January 19, 2022 I have a can line, that can handle 3 types of can sizes.... 400gr, 850gr and 900gr. I have created a capsule, based on HI / LO limites (set in Asset Framework) and the CanSetpoint Now I want to calculate the standard deviation of the can weight. These are individual measurements and the timing depends on the line speed (unknown) I want to know the 10 minutes rolling standard deviation fill weight, within a capsule. So start capsule 400gr can - xx amount of can - time 00:00:00 till 00:10:00 - STD 1 minute later: 400gr can - xx amount of can - time 00:01:00 till 00:11:00 - STD etc... Suggestions ...? Link to comment Share on other sites More sharing options...

Seeq Team John Cox Posted January 19, 2022 Seeq Team Share Posted January 19, 2022 Hi Robin, I would use a Seeq formula similar to the one below, with the Can Weight signal and your existing Can Production capsules as inputs. The key functions used are aggregate(), periods(), and inside(). Note that you could also do the std deviation calculation using Signal from Condition, using a condition created in Formula with: periods(10min,1min).inside($CanProductionCapsules). $CanWeightSignal .aggregate(stdDev(), // std deviation statistic periods(10min,1min).inside($CanProductionCapsules), // do the calc over 10 min rolling window every minute // but only for 10 minute capsules fully inside CanProduction capsules endKey() // place the calculation result at the end of the 10 minute window , 0s) // max interpolation between data points, use 0s if you want discrete result Hope this helps! John Link to comment Share on other sites More sharing options...

robin Posted January 23, 2022 Author Share Posted January 23, 2022 Thanks for the reply... using the standard deviation, based on Signal from condition is a Time-Weighted STD and this will not work... It should be an event weighted Standard Deviation (each individual can) I will try your second suggestion.... Link to comment Share on other sites More sharing options...

robin Posted January 23, 2022 Author Share Posted January 23, 2022 @John Cox... almost... I found a signal that indicated the production status, independent of the Can Size. This is the right trigger to calculate the STD per can I decrease the function to calculate it every 5 minutes, 30s 2 things.... can we add a (stepped) line.... and how we close the gaps... Due to calibrations, every 18 minutes or production interrupts there a gaps in the STD signal... can we fix this... ?? but many thanks for now... getting closer 😉 Link to comment Share on other sites More sharing options...

Seeq Team John Cox Posted January 24, 2022 Seeq Team Share Posted January 24, 2022 Hi Robin, 1) To answer your earlier question, to avoid the time weighted standard deviation, all you need to do is change the signal to a discrete signal and then apply the same formula: $CanWeightSignal.toDiscrete() .aggregate(stdDev(), // std deviation statistic periods(10min,1min).inside($CanProductionCapsules), // do the calc over 10 min rolling window every minute // but only for 10 minute capsules fully inside CanProduction capsules endKey() // place the calculation result at the end of the 10 minute window , 0s) // max interpolation between data points, use 0s if you want discrete result 2) To answer your most recent question, to convert your current result to a stepped signal rather than the discrete results you now have on the trend, you can use a Formula function named .toStep(). Inside the parentheses, you enter the maximum amount of interpolation, the maximum amount of time you want to draw a line connecting your calculated results. For example, the function below sets a maximum interpolation between data points of 8 hours. .toStep(8hr) Hope this helps! John Link to comment Share on other sites More sharing options...

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