POST No. 2407533
current-based position control not equal in both directions?
2019-08-09 18:51:22 Flamestar


I am building a gripper with four XH430-V350-R.

My problem is, that the behavior in both directions is not equal when I am using the current-based position control.

Counterclockwise rotation has a good behavior when using 3x2.69mA and higher.

Clockwise rotation has a good behavior when using a very high current as 20 to 30x2.69mA and higher.

Do anyone know why the Dynamixels have this behavior?

Is it hardware-based or is it possible to calibrate the rotation?

I also added a plot of the behavior.

The first curve is turn counterclockwise followed by turn clockwise with 10x2.69mA.

The second curve is turn counterclockwise followed by turn clockwise with 12x2.69mA.

The third curve is turn counterclockwise followed by turn clockwise with 14x2.69mA.

I hope anyone is able to help me with this "issue".

2019-08-09 18:51:22
2019-08-12 17:57:49 Will Son


Thank you for reporting the issue.

In case of very low current operation, there could be some differences due to mechanical margin of error.

As mechanical parts run in(break in), this differences will become narrower, but it is recommended to use with enough current.

Please let me know the 4 digit QC number of the product so that I can request more information from the manufacturing department.

Thank you very much.

2019-08-12 17:57:49
2019-08-12 18:15:23 Melf Martens


the XH430-V350-R which i made the plot with has a Q.C. Pass sticker on it with the number 1747.

for the other numbers I have to disassemble the whole Gripper :/

If it's the bahavior of the hardware I can live with that. But in my opinion it's a huge difference for just being the rotation direction.

Thank you :) 

2019-08-12 18:15:23
2019-08-13 09:45:15 Will Son


Thank you very much for checking the QC number.

I'll check with the manufacturing department to see if it is a hardware issue and get back to you as soon as I hear from the department.

Thank you for your patience and understanding :)

2019-08-13 09:45:15
2019-08-14 09:35:49 Will Son


I was told that as core motor and internal gears worn out, the performance could be decreased.

But it seems your XH430-V350-R is slightly off from the normal product range in terms of low current operation.

If you have purchased it recently and the warranty isn't void, please feel free to request RMA service.

You can request the service either via your local distributor or website.


Thank you very much!

2019-08-14 09:35:49
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