LinuxCNC S-Curve Accelerations

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30 Apr 2025 19:24 #327378 by PCW
Replied by PCW on topic LinuxCNC S-Curve Accelerations
Indeed if you set acceleration to 200, the scurve max acceleration will be 400 at inflection point.
Exceeding your max acc off 240.


I get the same error even if all accelerations are set to 100 in the ini file
The following user(s) said Thank You: Grotius

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01 May 2025 12:12 #327419 by Grotius
Replied by Grotius on topic LinuxCNC S-Curve Accelerations
@Pcw,

Thanks for reporting this.  For now i will keep this in mind, and will test this later on.

The [TRAJ] section is responsible for setting the planners max-acceleration values.
The planner doesn't look at the individual joint max acceleration values. Maybe that is causing trouble.

@All,

Ok, for the cia-402 component i made a home sequence intrusion in the homemod.so component.
It basicly enables external homing, and not triggering following error etc during this procedure.
All is done with a few hal pins.

When using the servo's internal home sequence the lcnc home sequence can now be done by a connecting a few hal pins.

For each joint, you can activate the cia-402 home sequence.
In this way, a non cia-axis, can be homed by lcnc's original method as usual.
 

1. You can set pin for enabling the cia-402 internal servo drive home sequence.
Set this flag "setp" in the .hal file after you load the cia component for example.

2. The cia-402 recieves a home command from homemod.so
Connect the cia-402 home command pin (input) -> homemod home-drive (output)

3. The cia-402 servo pos feebback is passed to the homemod.so when the servo is homing and changing position.
Connect the cia-402 pos-feedbak (output) -> homemod.so pos-fb

4. When the cia-402 drive is homed, it updates a flag in homemod.so wich set homed = 1.
Connect the cia-402 is homed flag (output) -> homemod.so drive-is-homed.

libhome

source code intrusion

Sinds i have no cia hardware, i tested this ok in a linuxcnc simulation config.
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01 May 2025 13:08 #327428 by PCW
Replied by PCW on topic LinuxCNC S-Curve Accelerations
I did set the acceleration in the TRAJ section, it does affect the acceleration
but the scaling seems not to be correct. The Acceleration/Velocity bounds are important
since they are per joint physical limitations.

(sorry if I am getting out the sandpaper when construction is at the chainsaw stage)

It is great so see  a jerk limited profile working with LinuxCNC as it fixes the inevitable
following error at the start/end of motion due to the impossibility of having instant force
application in any real drive system.
The following user(s) said Thank You: tommylight

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