> 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 ------------------------------------------------------------------------------ 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
