Relationship between LU (Length Unit) and Encoder Resolution

Hi all,

Can anyone explain the relationship between LU and Encoder Resolution? As i understand the accuracy of the controller depends on the resolution of the encoder, for example i have an 10 bit absolut encoder that means resolution is 360/1024 = 0.35 degree, how is the value of LU?

Thanks

An LU is what ever you want it to be.

For example, if you decide that 1 LU = 1.0 degrees, then your pulses/LU would be 2.844.

If you decide that 1 LU = 0.1 degrees, then pulse per LU would be 0.2844.

All of your axis calculations would be done in terms of LU's.  If your LU = 1.0 degrees and you want to move 30.5 degrees, then you would move 30.5 LU's.  If your LU was 0.1 degrees, you would move 305 LU's.  The purpose is to de-couple PPR from the engineering units.

I understand the LU concept clearly. But i want some more clarification. In the explanation its mentioned that resolution depends on the encoder. What i understand is, its based on the number of pulses. But how can select my resolution based on the encoder type and pulse values.

Example: I have 512 PPR encoder, and Gear Ratio 1:1. So i can not control the position of the load more accurate than 360/512= 0,7 degree?

In starter has a term Fine Resolution that i don't really understand how can i choose this value? because the definition of LU = Encoder PPR * Fine Resolution * Gear Ratio.

When Fine Resolution =1 is every thing clear. But when >1 i don't understand how can i determine this value

Thanks.