Author Topic: accel and velocity  (Read 13071 times)

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Offline prototype

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Re: accel and velocity
« Reply #10 on: January 30, 2012, 07:10:24 PM »
Would I be able to list all of my data and you be able to get me in the ball park?

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Offline RICH

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Re: accel and velocity
« Reply #11 on: January 30, 2012, 11:07:35 PM »
I don't don't use servos and the tuning is different than tuning steppers. That said, post if you wish and see
where it goes.

RICH

Offline Hood

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Re: accel and velocity
« Reply #12 on: January 31, 2012, 01:14:53 AM »
Accel is impossible to say, its machine/motor/drive /tuning dependant, Velocity should be possible to give a close value for but again servo tuning could affect that.
Hood.

Offline RICH

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Re: accel and velocity
« Reply #13 on: January 31, 2012, 06:38:48 AM »
HMMM....so we are right back to what the orignal question was and instead of echoing what has been posted i'll try again.
Yes, one can calculate, but one must be aware of what and how  the calculations are made and what they are telling them based on
varying inputs.

In practical applications one defines an acceleration desired and finds what is required to achieve it …or … accepts the value based on some other parameters.

That said, if one has all of the information required they could use one of the computer programs to calculate / evaluate a system. The problem is that unless
the data is very close to what the program uses for information and comparison ( motor / drive  system ) you will just be playing with numbers. The manufactures
programs provide a motor choice to fit the conditions, but in the end only actual testing ( motor tuning ) confirms the reliablility.  The three M's all interelated.

Maybe try out one of the programs and see if you really have the data and understanding required.

Have fun,
RICH


Offline prototype

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Re: accel and velocity
« Reply #14 on: February 01, 2012, 07:16:10 PM »
Thanks for the input guys. I will just start playing with settings and making adjustments. Someone had mentioned to me ( in person ) that I need to be careful of "noise" in the lines and possibly getting some type of magnet to put at the pc connection and the servo connections. But he doesn't know what the magnets are called so I have yet been able to find them.  I am going to find them and put them on. What other precautions can I take to reduce my risk of noise causing problems?

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Offline Hood

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Re: accel and velocity
« Reply #15 on: February 02, 2012, 03:05:35 AM »
I would imagine the "magnets" he was talking about were in fact ferrites and not magnets.
Hood

Offline RICH

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Re: accel and velocity
« Reply #16 on: February 02, 2012, 06:40:29 AM »
Quote
What other precautions can I take to reduce my risk of noise causing problems?


Shielded cables. Eliminate or reduce the noise source if possible. Using chokes, those ferrite magnet things , can help but depends on what is actualy happening.

RICH

Offline prototype

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Re: accel and velocity
« Reply #17 on: February 02, 2012, 09:03:28 PM »
Im going to measure my wires and order Ferrites tomorrow.  My system uses differentials ( I think its what they are called) to run the 4 wires from the encoder to an rj45 plug. Then cat 5 wires to the drives. Do they sell shielded wire for cat 5?

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Offline Hood

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Re: accel and velocity
« Reply #18 on: February 03, 2012, 03:33:40 AM »
If your encoders are differential then shielding is not really required as the differential signalling is very noise immune.
Hood

Offline prototype

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Re: accel and velocity
« Reply #19 on: February 03, 2012, 04:33:05 PM »
That's what they are. Differential line drivers. Where else may a noise issue come from?  All of my step and direction signals are ran through the flex that the servos were wired through with its original setup.

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