Hoist positioning

[seppoalanen]

Hej seppoalanen

I have looked at your S7-image, and I am wondered what is the "SIFT" parameter for.

Jesper.

 

[lauu]

Hej seppoalanen

Have patience with me, I still don't get it(SIFT)?

Is it to compensate for overshooting target because of load inertia?

Jesper

 

[seppoalanen]

Yes, there are a few tools for exacting stopping to target position. Usually motor have fit with el-mech. brake and it takes 100-200ms before it works.

Lower Min-spd gives better precision, stop-command cames when motor have allmost zero-spd, so Window-size can be smaller also.
I have done cart who max-spd is 3000 mm/s, 2500 kg mass with Laser location measure. Cart stops to same location from both direction, exacting is the same (1mm) than in Laser. It takes around 1,5 seconds from 3000 mm/s to zero.

br. Seppo

 

[lauu]

Hej Seppo

There is a el-mech. brake on the motor, but have does the "SIFT" parameter works do you subtract the Target position with "Stif"?

Jesper

 

[seppoalanen]

Hej Seppo

There is a el-mech. brake on the motor, but have does the "SIFT" parameter works do you subtract the Target position with "Stif"?

Jesper

Hej Jesper
Library file is 375k http://www.plctalk.net/qanda/attachment.php?attachmentid=4807&stc=1 so I publish it here.

 

[lauu]

Thank you.

I will have a closer look at that!

Jesper.

 

[lauu]

Hej Seppo

I think I am on the track!

Jesper

 

[lauu]

Hej Seppo

In your Example the SPD_REF will always bee MN_SPD(I think) so I made this, right/rong?

Jesper

 

[Tech7]

Sick Laser

Lauu, I know for a fact that sick makes a laser measuring device that connects directly to profibus. The idea of using the drive to do the positioning is a very good one as long as the Micro Master has or will accept a positioning module.

Tech7

 

[seppoalanen]

Jesper, See Network 4:

MOVES ZERO TO #SPD_REF when IN THE WINDOW

Try put L#4995 to A_LOC input or growing up the WIN_SZ
ps. Please edit symbolic name "SQR_SPD_REF_Vacon" and description to SQR declaration ramp for the Vacon VFD

Ps. MicroMaster uses +/- 32.000 or something like that, see the manual and change MX_SPD/MN_SPD. Try different MUL input value for Micro Master.

Send SPD_REF to your MicroMaster VFD-program block as input.

br. Seppo

 

[lauu]

Hej

Tech7
That the one I will bee using, but all the positioning is to bee don in the PLC. No need for special position module.

Seppo
I have seen network 4 and I now what is does, but I still think that the SPD_REF will always bee = MN_MIN in your example (when it is not in WIN_Z).

In the image below(the original FC) The SPD_REF should bee 10000, if I understand it right. You compare the calculatet result with MX_SPD and MN_SPD but the calculation will always bee less than 500:

Speed = SQR(5000-0) * 3.14 - 5 = 217

I can raise the "MUL" parameter, but I don't think that is the way to go, am I right?

Jesper

 

[seppoalanen]

In the image below(the original FC) The SPD_REF should bee 10000, if I understand it right. Right, it is max Output.

You can freely play with MUL.
Speed = SQR(5000-0) * 140 - 5 = 9889.6
On the field I used multiplayer 140.0. The speed ref was +/-100 in original program and later I have added more exactness becourse in slow motion 1 Hz change is much (from 2Hz to 1Hz), 0.01Hz is better. SHIFT was 400.0 in last time on the field. Seems that 5000 mm distance is the point when dec. starts.