AD SureServo Question

I've got an application where I need to move the drive to a target position, changing velocities 4 times along the way.

I figure either change the velocity control register (I'm using register-based positioning via modbus), or set up 4 indexes ahead of time and execute a blended move. Either is acceptable. In fact, I'd prefer the latter.

Thing is, AD support told me this can't be done. Now, I don't mean to question the experts, but the same fella told me you can't set an input to stop the drive and cancel the movement once initiated.

This seemed kinda hair-ball to me, and I checked for myself. The manual clearly says you can do this (page 5-50 and 6-11), so I don't trust what this guy has to say. I'll turn to the real experts here.

Can somebody tell me how to either change velocity on a movement under execution in Pr mode, or how to blend a set of four indexes without stopping between them?

Thanks!

TM

I haven't had an opportunity to work with the Sure Servo line yet, but there are many motion controllers where you can't change the velocity once you have initiated a positioninig move command.

There are a couple of ways that I have implemented what you want to do (on other servos).

1. Some servos have a feed rate override control that allows you to change the velocity on the fly. Look for something like that in the Sure Servo command set.

2. Put the servo into follower mode and control the master speed. You may be tempted to try to change the follower ratio on the fly, but many motion controllers won't let you do that either.

This is easy, but maybe not on a SureServo

TIm, you should post a link to the .pdf file of the manual. I looked at page 5-50 and it was about jitter. 6-11 was about position mode indexing. It looks to me like you need to be in velocity mode to change velocities on-the-fly.

I would hit the easy button and find a controller that has a speed at position command where one just needs to specify the postion and velocity at that position and the controller figures out the rest. This way you concentrate on the end result instead of how to achieve it. Then you are done in a couple minutes and ready for

Did they update it again?! Geez, wish they'd hold still.

My reference was to Parameter 2-50 :

Clear Position Mode​

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Range: 0 ~ 2 Units: n/a​

Default: 0 Control Modes: P​

• This parameter is used when a digital input is configured as a Clear Pulse function (DIx set to 4). (Refer to P2-10 ~ P2-17 to assign the DI functions.)​

Settings:​

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Despite the shortcomings - and it has a few (no high power drives, metric footprints incompatible with NEMA mountings on the motors) it does have internal positioning controls and is readily controlled with Modbus, and therefore Unitronics.

However, having finished a project with a Trio and a Yaskawa recently I've got a real affection for that combination, and am waffling about which way to go.

Incidentally Peter, while I have a moment, I owe you and Keith some serious thanks. The project in question was the one I asked you about torque control. I did it, implemented it, total rebuild, done in under three weeks... and landed a fat promotion for my efforts. Thanks guys.

TM

Sorry to bring this one back up a week later, but there was an addendum I felt I needed to put to it.

It seems the folks at Automation Direct are aware of this group, and saw my post, and moved right on it. I got phone calls and emails offering help for my questions, and all in all, I was very satisfied, even if the answer wasn't what I'd hoped for (No, still can't change velocity on the fly, although you can preset electronic gear ratios, and may be able to accomplish the same thing thataway. Hmm, more experiments...)

Anywho, you can really tell the quality of the service when the service comes looking for you. Great bunch over there, and I'm very happy to know they're here as well

C-ya,

TM

So how are you going to ramp the gear ratios up and down and still reach the desired location? I am curious.

Good question! And I haven't a clue. It was just one suggestion that was floated.

Basically, I wanted to let people know that these guys really went out of their usual way to try and help. While I like the SureServo, as I pointed out earlier, it has a few drawbacks. Suitable for some things, not for others.

Thanks!

TM