DYNAMIC CHECKWEIGHER

Weighing in static mode assumed that m=P/g,

where m - mass of product obtained by weigher's readings ; P - weight force; g - gravity acceleration.

Weighing in dynamic mode could be expressed as m'=P/g+Pdyn(t),

where Pdyn(t) - additional dynamic factors/forces expressed here as function on time caused by impacts, vibrating due to a kinetic and a potential energy mutual conversions in a mechanical system "weigher - product", relative motion of system of coordinate where weighing had been performing.

Pdyn(t) is affecting weighing result and as a stochastic process cannot be ever determined completely.

Dear Caramba,

Thanks for sharing the usful information

Have a great Day.

NAK

Good morning

I used to work in a factory that made cd dvd. We used to use weigh machines to check if the disc and its contents where present. We found that the same product could weigh a few g under or over if we passed it over the scales a few times. Ifound that the position of the case on the belt caused this pproblem as we have the line speed faster so the sensor would trigger at diff times if the case was twisted. We also found that the guid rails where lowe and a build up of dirt under these would apply pressure and this also caused a problem.

Unfortunately it's inevitable for such kind of weighing technique. You could apply parallelogram design for scale platform to make it some less affected to case position. It's not panacea though.

Two or three weighing platforms installed one by one might improve accuracy.

May be an interesting experience result for you. problem was weighing on the fly up to 2kg with the lowest possible error. of course a dynamic weighing leads to errors. Most of them due to oscillations consequence of a steep load variation. the problem was to damp vibrations in a as short as possible laps of time.

I designed and we used an active damper velocity controlled and were able to go as down as 1/2000 error. the project was interrupted due to lack of founding but results were very very promising.

The approach is in fact possible to all loads not only as small as the considered one.

If you come across such a problem I could be of help.

Hello nick name,

Thank you,

I had had quite good results too and developed some ideas as well as some of them had been implemented. Indeed 1/2000 sounds as a very promising, but I'd think there should be predetermined conditions for better estimating for which e.g. weighing on ship(vessel), truck scales, conveyor scales, scales for cattle, scales as part of dispensing system etc. Or for either?

Weighing during flying? Yes I had similar theoretical and experimental researches (not so advanced as desired) for high speed conveyors when bulk material is flying between idlers and for short platform applied at truck scales.

Yes. I guessed at the time that such an intellectual measure as just active(controlled) dampening measure(device) should make a great difference for overall accuracy. Something like is applying for output signal dampening, but it's not just the same. Do you agree? Unfortunately, process of dynamic weighing is not linear, plus while it's oscillating it's barely strongly periodic.

I've stopped my researches due to similar reasons as you did. But I hadn't left a hope to continue one day. If I find ways for researching task formulating I'd ask you to have a look. I hope maybe it'll be interesting and profitable for you as well.

best regards,

caramba