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#1

# question: I am in a debate concerning motion.

question: I am in a debate concerning motion.  I believe home means home.  As in you are resetting position to zero.  Then start.  Explain your opinion of home, and homed.
01-04-2014 03:29 AM
Top #2
My opinion is that home represents a known reference position. It need not be zero.
01-04-2014 05:41 AM
Top #3
I agree with that. Home is just a start point, correct? But when you are not at home, you should not indicate home? Or you say "homed"?
01-04-2014 07:47 AM
Top #4
So when you first "wake up" a motion system is does not know where it is. It needs to be "homed". Once you "home" it by moving it to a known, repeatable position it will remember where it is relative to that home position. In answer to your questions, my answer is that if you have performed the homing routine and the system has a valid reference (it knows where it is) it has been "homed", even though it may no longer be at the "home" position. Make sense?
01-04-2014 09:59 AM
Top #5
@Scott Baker your absolutely right. Home is not always the Zero point in a positioning system. It is the point all other positions in the system are based on. ie -Z +Z from "0" with zero being what is termed Home. Makes the math easier in 3+ co-ord systems. in actuality the encoder 0 (for incremental types) may be at one end or other of axis travel.
01-04-2014 12:17 PM
Top #6
Here is what sparked the debate. There is a machine coded with a button that lights up saying "Top Homed" and this stays on the whole time during operation of the servo. Then in the code, they use a sensor input for the "home" position. However, the output is " Top Homed" and that is sent to move the servo...but they seal it in so that it stays on the entire cycle. Thus, even if it homes, we don't really capture it at home...its just been homed. It was confusing the way it was written because the home sensor barely comes on, and then there is a servo reset and the same button is pushed to home that comes on all of the time.....so the operator pushes the button and the button lights up saying its home, but it doesnt move the servo. He has to go back in and move the actuator up and down and then reset the MCR and then reset and then home....the reset button breaks the seal on the home indicator...otherwise it never goes off. To me, "homed" should only come on if you made it home. It should not stay active the whole cycle.
01-04-2014 03:00 PM
Top #7
Hmm, actually sounds like you have a problem there. All machines that I have worked with that require a home did it automatically. What is the reason that the operator manually moves the actuator?
01-04-2014 05:21 PM
Top #8
I agree, not the best written program, presumably the lamp means " has been homed since the last power up/ E.Stop
01-04-2014 07:31 PM
Top #9
That's what it sounds like, by manual do you mean "jog" or physically moving the axis by hand.
01-04-2014 09:52 PM
Top #10
when we brake the MCR circuit, and then go to restart, we have to pull the piece up the linear actuator and then hit home. If its close to home, it won't go, so the operator has been pulling it up the tracks by hand and then rehoming.
01-05-2014 12:08 AM
Top #11
The "has been homed" is in the code as well, and it has to stay on for the whole cycle. Thus the confusion on my part when I went to try and fix it. The only time this realistically would happen is on rework or a jam, or if you have to go in to replace a sensor. Anytime the door to the cage is opened, the circuit stops. Seems like it loses where its at unless the guy pulls it up, so ...I don't know...had another idea, was going to try this week.