On 04/03/2016 10:14 AM, Nicklas Karlsson wrote: >> On 04/03/2016 09:31 AM, Nicklas Karlsson wrote: >>>> Lets say there are three different G Code files, A, B and C. >>>> >>>> In file A, the coordinates are such: X x.x Y x.x >>>> >>>> In file B, the coordinates are such: X x.xx Y x.xx >>>> >>>> In file C, the coordinates are such: X x.xxx Y x.xxx >>>> >>>> For simplicity's sake, no Z axis and the units are inches. >>>> >>>> Using file A for example, with the coordinates only given with 0.1" >>>> precision, what exactly does the controller do? Does it actually work >>>> to 0.1" precision or does it work to moreprecision, vis-a-vis when >>>> making moves? >>>> >>>> Is file C, with precision to three decimal places the standard precision >>>> in controllers, or do we just use three decimal places in the G Code >>>> because it's good enough for gummint workand the controller can actually >>>> make more precise moves (dependent of course on the machine, the >>>> mechanics and the electronics)? >>>> >>>> Mark >>> Machine resolution depend on for example: Movement for each step or micro >>> step for a stepper motor. Resolution of encoder for a motor with encoder. >>> Resolution may be degraded from this but if number of encoder pulses is >>> sent back to linuxcnc this should be the maximum resolution. >>> >>> >>> Then it might be worth noting: Float point according to IEEE 754 is 23 bits >>> and double 53 bits regardless of decimal point position. Float work great >>> for values read from an analog to digital converter since number of >>> significant bits will be the same regardless of decimal point position >>> which vary depending on what value is representing. >>> >>> For float it may also be worth noting values will be closer together for >>> small values. >>> >>> Then unit is changed decimal point will be moved and there will be some >>> rounding errors so then using for machine control the question between >>> float and double will be. Is 23 bits resolution enough? Or is 53 bits >>> resolution needed? Are there any difference in computational speed? >>> >>> >>> Regards Nicklas Karlsson >> I get that, but let's assume the theoretically perfect machine. >> Disregard the shortcomings of the stepper/drive, servo/drive, or any >> slop and inaccuracy that would exist in the typical machine hardware >> like bearings, etc. > Machine accuracy because hardware is not perfect is a hard problem. > > > Nicklas Karlsson
That's why in this theoretical discussion I asked to disregard the actual machine accuracy and presume you had the so-called perfect machine. What I was looking for was how precise/accurate/resolute the controller would be. Mark ------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://pubads.g.doubleclick.net/gampad/clk?id=278785471&iu=/4140 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
