What is the minimal encoder resolution for a low speed rotation

Hello,

I am using a roboteq controler SDC2130 to drive a differential mobile robot.
Motors are DC Motors with a 71:1 gear box and a 7 Pulse per resolution encoder.

So taking into account my gear box, I have a 71*7 = 497 Pulse per Wheel resolution.

I need to be able to move slowly at something like 0.22 wheel revolution per seconds. (105 pulse per seconds).

I read that the internal control loop of my roboteq controler is at 1Khz (1 pulse every 10 controler loop !).

So my question is : Is there a minimal pulse count per controler loop ?

Or in other words : What is the relation between the speed accuracy, the control loop rate, and the pulse per revolution ?

Thanks

I will self reply thanks to a mail send to the support.

To measure velocity encoder will compare the coder value of the current cycle with the value 10 ms in the past (10 control loop at 1kHz).

This value is hard coded, and can't be changed.

At least one tick must occurs during the 10 ms period.

So minimal measurable velocity (in RPM) : 60 / (4 * PPR * 0.010)
4 : Because we use a quadrature encoder, And 0.010 is the 10 ms period.

So I need to change my encoders !