How to setup gearbox/reducer

Hello,
I have AC servo motor which has harmonic gearbox with ratio is 80:1
How can I setup LCNC to work correctly with the gearbox ratio ?.
Thank you.

Depending on if your a controling your servo closed loop or open loop in Linuxcnc. You have to calculate the encoder counts or steps per unit of measure that you wish to use with this joint. The units could be inches, mm or other if the joint is linear, or if the joint is rotary the units would be degrees, radians, revolutions, or other.

If for example this joint is for a rotary C-axis in degrees and your servo motor is closing the loop to Linuxcnc with a 2000 line encoder directly coupled to the motor and the motor is directly connected to your 80:1 gearbox. You would use 2000(4)*80/360=1777.777778 counts/degree. So in your ini file you'd put ENCODER_SCALE = 1777.777778

Hi Tommylight,
My system is:
- Drive: AC Servo EtherCAT drive
- Motor is installed in SCARA robot
- The encoder: 17 bit optical absolute multi-turn. Its resolution is 131072, so I understand it has 131072 counts for one turn.
- The mechanical gearbox ratio is 80:1, fixed with motor.
Hope it is all you need Thank you.

Hello Todd,
I understand that you make example of "incremental encoder" with quadrature.
My encoder is 17 bit absolute multi-turn type, so the counts for one turn is huge value 131072.
I calculate: 131072*80/360 = 29127.111111. Is it still correct to apply ?.

I put ENCODER_SCALE = 29127.111111 to INI file, but nothing happen.
I understand need to revise HAL file to use ENCODER_SCALE, but it seem encoder component is only suitable to incremental encoder type.
linuxcnc.org/docs/devel/html/man/man9/encoder.9.html

Please advise Thank you.

Hello Aciera,
Can you share your note here ?.
I searched in DH-parameters for Genserkins and Vismach/Melfa-sim, could not find your note or anything mentioned about absolute encoder
Thank you.

Hello Aciera,
I have no "nyx" hardware to test, so I chose other option.
I revise "pos-scale" of cia402: "gear ratio" * "encoder counts" / 360 degreeIt runs well this moment.

Have you triedin EtherCAT option ?.
I think it is better solution. My drive does not support, so I could not try. Please share your experience.
Thank you.

DPFlex wrote:

Hello Todd,
I understand that you make example of "incremental encoder" with quadrature.
My encoder is 17 bit absolute multi-turn type, so the counts for one turn is huge value 131072.
I calculate: 131072*80/360 = 29127.111111. Is it still correct to apply ?.

I put ENCODER_SCALE = 29127.111111 to INI file, but nothing happen.
I understand need to revise HAL file to use ENCODER_SCALE, but it seem encoder component is only suitable to incremental encoder type.
linuxcnc.org/docs/devel/html/man/man9/encoder.9.html

Please advise Thank you.
 

This is a little bit of late reply, the encoder component documentation you referenced is a software encoder counting component applicable for reading an encoder via gpio such as through a parallel port. This would not be applicable to your situation with Ether CAT. But it sounds like you are on the right track now.
(I have no experience with Ether CAT.)