Tuning an optical encoder with a linear actuator

[kmhijazi]

Hello everyone!

I am trying to get an optical encoder (5 lead single ended, incorperated into an Ultramotion D2 series linear actuator) to read the position of the linear actuator's position to 4 decimal figures precision (0.0001), and the DAQ I am using is NI cDAQ 9121 with 2 channels. I decided to use the 65 mV configuration. The encoder has ground, channels A and B, index and 5V leads, of which I have omitted using the index and channel B. Channel A is connected to the AI+. The linear actuator has a scaling of 20,000 steps per revolution and a movement of 4mm per revolution (point to point configuration of the stepper motor drive ST5-S, by Applied Motion). 

I am not sure if the above configuration is suitable, but I am limited to the current equipment. I have coded the program using LabVIEW 2014 and, while it seems to give a good estimation of the displacement to the nearest 1 mm,  it is not recording the fractions and counts anything that is 1mm or less as simply 1.

My question is actually threefolds:

1) How can I tune the encoder to read the exact measurement to the nearest 0.0001 accuracy?

2) Am I using an appropriate configuration for the leads?

3) If the problem is not one of the above, could it be something concerning the DAQ software settings and/or the code itself?

Thanks for your advice in advance!

[Danubio]

Hey kmhijazi,

Here I share the most general documentation about using encoders with DAQ devices:

Using Quadrature Encoders with E Series DAQ Boards

https://www.ni.com/en/support/documentation/supplemental/21/using-quadrature-encoders-with-e-series-...

Then, here’s a second resource where you can find more details that you can adjust to improve the measurement (i.e the Decoding type, which will however depend on your encoder specifically):

Encoder Measurements: How-To Guide

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA03q000000x1riCAA&l=en-US

I hope this can help.

Regards,

>>Daniel C.