## Strange Trajectory Planner behaviour

Moderators: TomKerekes, dynomotion

gnrules
Posts: 11
Joined: Fri Jun 14, 2019 7:06 am

### Re: Strange Trajectory Planner behaviour

Hi Tom,
I added 4th decimal digit to my code and now it is very smooth without any dicontinuity even in limited velocity segments.
You were right about truncation/rounding error relative to decimal digits in g-code.

It was something that we would experiment because we use 0.5um glass scales, but now it is mandatory!!

Thank you for tour support.

Best regards

Giancarlo

GabrielR922
Posts: 79
Joined: Thu Aug 13, 2020 10:07 pm

### Re: Strange Trajectory Planner behaviour

Hi Tom and Giancarlo.

Let me see if I understood.

Even if I have a precision of ~0.01mm, it's best to post the code with 3 decimal cases? ig: 0.001?

Is there a tutorial to how plot the data like both you are doing?

Thanks,
Gabriel

TomKerekes
Posts: 1602
Joined: Mon Dec 04, 2017 1:49 am

### Re: Strange Trajectory Planner behaviour

Hi Gabriel,
Even if I have a precision of ~0.01mm, it's best to post the code with 3 decimal cases? ig: 0.001?
Yes it a good idea to have numerical resolution an order of magnitude better or more than the precision you are trying to achieve.

Is there a tutorial to how plot the data like both you are doing?
The charts I posted regarding the GCode segment lengths and angles were simply created by editing the GCode to remove non numeric characters (GXYZ) then pasting into Excel using text to columns. Then I calculated the Deltas. From deltas I calculated lengths and angles. Then deltas of those. I've attached it.

To capture data within KFLOP you might read the wiki here.
Attachments
GCodeNoise.xlsx
(39.9 KiB) Downloaded 15 times
Regards,

Tom Kerekes
Dynomotion, Inc.