# Cycle time round up at Zero Speed

**URL:** <http://discourse.heig-vd.ch/t/cycle-time-round-up-at-zero-speed/282>\
**Category:** OpenCN Framework\
**Created:** [February 24, 2022, 3:31am UTC](http://discourse.heig-vd.ch/t/cycle-time-round-up-at-zero-speed/282 "2022-02-24T03:31:02Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![yakunix](http://discourse.heig-vd.ch/letter_avatar_proxy/v4/letter/y/bb73d2/32.png) [@yakunix](http://discourse.heig-vd.ch/u/yakunix)\
**Post date:** [February 24, 2022, 3:31am UTC](http://discourse.heig-vd.ch/t/cycle-time-round-up-at-zero-speed/282/1 "2022-02-24T03:31:02Z")

</div>

When the cutting stragety is used, the jerk used for NZ type curve did not consider the round up of the cycle time. That is, the duration of the whole motion is not an integral multiple of the cycle time. Will it cause vibration of the machine? Maybe we should adapt the jerk at runtime to round up the duration.

---

<div class="post-metadata">

**Author:** ![Raoul](http://discourse.heig-vd.ch/user_avatar/discourse.heig-vd.ch/raoul/32/21_2.png) [@Raoul](http://discourse.heig-vd.ch/u/Raoul)\
**Post date:** [February 24, 2022, 6:24am UTC](http://discourse.heig-vd.ch/t/cycle-time-round-up-at-zero-speed/282/2 "2022-02-24T06:24:05Z")

</div>

not sure if I understood your question.  
Are you talking about the “zero speed” handling using a constant pseudo-jerk ?

The start phase is not critical : at a certain moment the “zero speed algorithm” gives over to the standard feedrate planning.

The stop phase is more critical, since we _exactly_ aim zero speed and zero acceleration at an integer multiple of the sampling period.

---

<div class="post-metadata">

**Author:** ![yakunix](http://discourse.heig-vd.ch/letter_avatar_proxy/v4/letter/y/bb73d2/32.png) [@yakunix](http://discourse.heig-vd.ch/u/yakunix)\
**Post date:** [February 24, 2022, 6:31am UTC](http://discourse.heig-vd.ch/t/cycle-time-round-up-at-zero-speed/282/3 "2022-02-24T06:31:40Z")

</div>

The last two curve piece’s end type is NN and NZ.  
The NN type uses Taylor series for the evaluation. When uk \> 1.0, it will transit to the NZ curve. So the first deltaT for the NZ curve is less than one cycle time. I mean for the remaining part, is there any code to ensure the remaining time is an integer multiple of the cycle time?

---

<div class="post-metadata">

**Author:** ![Raoul](http://discourse.heig-vd.ch/user_avatar/discourse.heig-vd.ch/raoul/32/21_2.png) [@Raoul](http://discourse.heig-vd.ch/u/Raoul)\
**Post date:** [February 24, 2022, 7:20am UTC](http://discourse.heig-vd.ch/t/cycle-time-round-up-at-zero-speed/282/4 "2022-02-24T07:20:57Z")

</div>

ok, I understand your point.  
I’ll have to dive into the code; it might well be an issue.

Thanks for pointing out !