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HKT22 optical encoder newbie question / integration

Posted: Wed Jun 05, 2019 2:34 pm
by nm17

I am considering HKT22 optical encoder, had a very good look on Phidgets website but wasn't sure how it integrates (or doesn't) with other Phidgets.

My setup currently is stepper + controller + encoder, wanting to drive stepper to up to +-0.15mm precision.

Ideally, I would like to use rotary optical encoder and have a closed loop on the Phidgets board. That is, I plug HKT22 optical encoder into to Phidgets controller board (eg DCC1000_0) then set the stepper target to eg 100 and the controller board uses encoder to figure out if any missteps have happened and adds steps until it reaches the target position of 100.

Is this possible / available to buy? If yes, what do I need in terms of controllers?

I understand I can use my own software to read the optical encoder and then instruct controller/stepper motor. This is all fine but introduces unnecessary delays in communication and many components that could fail in the process (from hardware to software).

If control loop with custome software is the only way, is it possible to connect HKT22 to Phidgets InterfaceKit 1010 as (presumably digital) input?

Thank you

Re: HKT22 optical encoder newbie question / integration

Posted: Thu Jun 06, 2019 1:35 pm
by jdecoux
We do not currently have a stepper controller with built-in encoder input. The only way to do what you are looking for with a stepper motor is using an encoder interface and custom software.

I would recommend the ENC1000 Quadrature Encoder Phidget to accurately read the position of your encoder.

Digital inputs on Phidgets like the Phidget Interface Kits are intended for use with slower signals, such as detecting if a button is pressed, and are not suited to high-frequency operation.

Re: HKT22 optical encoder newbie question / integration

Posted: Mon Aug 12, 2019 11:05 am
by fitchett
Our Stepper Controllers don't do closed loop control; but our newer DC Motor Controllers do. DCC1000 and DCC1002 both accept an encoder input, and using the Proportional API object, you get a interface similar to a stepper motor, but using a DC Motor. Depending on your application, DC Motors can be much more predictable than stepper motors. Internally, we've used DC Motors to control linear motion, closing the loop with a linear encoder. Incredible accuracy.

There is some extra complexity to getting the Proportional controller set up in your software, but this is still way simpler than implementing an external control loop on a stepper motor.