Using External encoder with Omron Servo

[PLC Killer]

Hi there

I am working on a project where Omron servo drags a part to a certain position using belt mechanism, But to avoid any slippage we decided to put an external encoder directly on the part.

I was wondering what is the best to approach to drive the servo using the position of this external encoder. Is there any way that it can be configured directly with the servo? I am fairly new to coordinated motions, any help will be appreciated.

Thanks

[photovoltaic]

Depends on the servo drive. Do you have a G5 drive?

[PLC Killer]

Actually, I have 1S series drive.

[photovoltaic]

So the 1S doesn't support a fully closed loop. Off the top of my head:

1) Reach out to your Omron MSE regarding a function block to perform this

2) Use the second encoder for fine tuning with Jog or relative movement functions.

3) If this is backlash-related try the backlash compensation feature in the drive.

[Crossbow]

The encoder can be configured as an input motion axis.  Then you can look at the position of that axis for verification.

[PLC Killer]

@Crossbow  Hmm.... But I think I'll limited to only Jog commands. won't be able to use Move commands with this setup.

[Crossbow]

Encoders are input data.  You can use standard instructions to look at this data. Standard instructions like math and compare work with LREAL data, which is how the encoder axis position would be stored.

Encoders are not output data, so motion function blocks have no control of an encoder axis.  You can't jog an encoder...

[photovoltaic]

31 minutes ago, PLC Killer said:

@Crossbow  Hmm.... But I think I'll limited to only Jog commands. won't be able to use Move commands with this setup.

Not necessarily. I personally would use relative move instructions. The distance to move would simply be (desired position from field encoder - Current position from field encoder)

This is assuming you always do this on approach ie. backlash has been taken out of the system.

If the mechanical rigidity is such that this isn't accurate then jog would be best.

[PLC Killer]

1 hour ago, photovoltaic said:

Not necessarily. I personally would use relative move instructions. The distance to move would simply be (desired position from field encoder - Current position from field encoder)

This is assuming you always do this on approach ie. backlash has been taken out of the system.

If the mechanical rigidity is such that this isn't accurate then jog would be best.

That's very smart approach, never thought about that before.

Well, the only reason to get an external encoder was to overcome any mechanical slippage in the system (it is a belt mechanism driven by servo which pushes the part forward by friction). I better get the design changed and get G5 series drive for full closed loop.

Thanks everyone for your support!!!!!!!

[photovoltaic]

1 hour ago, PLC Killer said:

That's very smart approach, never thought about that before.

Well, the only reason to get an external encoder was to overcome any mechanical slippage in the system (it is a belt mechanism driven by servo which pushes the part forward by friction). I better get the design changed and get G5 series drive for full closed loop.

Thanks everyone for your support!!!!!!!

If the drives haven't been specced you can definitely look at a G5. Just be cautious - they are a bit scarce with the global supply issues at the moment and the encoder interface is pretty specific as to what types of encoders it supports.