Dynomotion

Group: DynoMotion Message: 10344 From: ericncn Date: 10/20/2014
Subject: preventing error accumulation

I would like to know if the Kmotion/Kflop system could have any tendency to generate error accumulation.


I mean, I assume that the G0/G1 moves are floating point quantities that are converted (rounded) to an integer number of steps via the counts/inch parameter. I would like to know if the rounding generated in each move, adds up to previous roundings so that after a certain numeber of moves, one or more steps could be lost (or added).


What I really want to know is, as I'm very likely going to add a reduction ratio between servos and screws, if _any_ ratio would work or in order to prevent error accumulation there are ratios to avoid.


For example, it seems me that if the count/inch value resulting from the chosen ratio isn't an integer number, there will necessarily be some error accumulation.

Are there other known conditions to avoid?


Thank you, regards

EC
Group: DynoMotion Message: 10355 From: Tom Kerekes Date: 10/20/2014
Subject: Re: preventing error accumulation
Hi EC,

You shouldn't need to worry about that.  The counts/inch value doesn't need to be an integer number.  Positions are calculated using absolute floating point operations (that's where the name KFLOP comes from).  At the final stage the "step" position is chosen that is closest to the desired destination.  Using absolute calculations avoids errors accumulating.  For example to move to an absolute position of say 1 inch will always calculate to the exact same integer step position irregardless of how many previous moves were made.

HTH
Regards
TK