I have an incremental encoder with single-phase output. Is there any way to use it for position control(not speed) while only one signal exist at encoder's output?

I mean is there any way to decode encoder's position with only one signal?

 

The problem is detecting direction of motion. You can use a counter to see how far the encoder has moved in one direction. However, if the motion reverses direction, the counter will see this as just more motion, not subtract increments to record the negative direction movement.

So, if you always advance, and never move back, you can control postion with a counter.

Eric
www.icpdas-usa.com

 

With a single phase you can measure distance (rotation)
but not direction and the resolution will be 1/4 that of a
quadrature output. You can, however measure speed.
You would use a simple counter rather than a quadrature
decoder and counter.

Regards
cww

 

Such type encoder doesn't allow you to define direction of rotation that is possible with two encoder's channels only. And because that it intends for speed control only.

 

No, in general you cannot keep track of position by decoding only one phase of a quadrature encoder. That is because looking at one phase you cannot tell when the direction reverses, so your counter would not know when to count up and when to count down. However, if you have an application where the rotation is always in one direction and reversal or stopping does not happen, then you could know position by counting the pulses on one phase.

Robert Scott
Real-Time Specialties
Embedded Systems Consulting

 

I don't know how you will use just one pulse output. but here is a couple of ideas.

You can figure out how far you have traveled by counting pulses but with just one pulse how will you be able to sense direction of travel?
You could use an Up/Down counter if you know the direction but that can get out of sync when you change.

Having said that, I thing printers sometimes use a single pulse to determine the location of the print head on the page. i.e. related to a home position switch.

Hope this helps
Roy

 

Some of the very early disk drives successfully used a single phase pulse technique for position control. As Roy said, you have to always reference it to a home position. The direction of motion can generally be determined by the direction of motion commanded to the prime mover, and of course this assumes that all motion is as a result of the prime mover. Once the final position is attained, some kind of mechanical stop or brake is necessary to keep everything where you think it is. By today's standards, its crude, but it does work!