Author Topic: Problem Homing  (Read 73 times)

sheaton

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Problem Homing
« on: February 20, 2021, 08:34:52 PM »
I bought an RV1s about a year ago and have found some time to bring it back to life now.  I have not seen it working.

The problem I have is with the homing the arm for the first time.


I have run armtest.exe and found the following (see also image attached, arm.jpg) :

>>

Analog input 6 (X Res) reduces from 255 to around 6 and the tick in box 6 appears when the forearm is rotated around its elbow and the angle between the forearm and upper arm is approximately 135 degrees.

Analog input 7 (Y Res) reduces from 255 to around 6 and the tick in box 7 appears when the arm is rotated around its shoulder and the angle between the north-south axis of the base and the upper arm is approximately 20 degrees, with the elbow to the left of the line.

>>



My problem comes when I run RVplace and open the file Demo-pcb.job.

The machine finds the limits for the Z and rotation axes successfully, but I am having problems with X and Y.


With the upper arm starting in the E-W direction and the forearm in the N-S direction, the homing movement commences clockwise at the shoulder (away from the Y limit switch position) and has to be stopped before the elbow hits the back of the cabinet. 


1. I would like help with confirmation that the X and Y limit switches (optos ?) are operating in the correct location when running armtest.exe (in my attached image arm.jpg) ? 

2. If this is all correct, am I starting with the arm in the correct position (arm position 1 in the attached file park.jpg) ?

3. If this is all correct, surely the should the arm should not commence rotating at the shoulder clockwise (away from the Y limit switch) ?

4. I have tried starting with the arm in position 2, and in this case it finds the Y limit successfully.  But I don't think this starting position is correct.  And what the arm does afterwards is worrying me and I have to emergency stop it.


I would be grateful for any help with this as I am struggling with the fundamantals.

Many thanks.



Further to the above, I have removed the baseplate front cover and see that each pulley has two areas with slots.  Each pulley has a single slot, and also two slots about 5mm apart further around the pulley.  This means that during armtest.exe there are two positions where the limit switches are activated.  I have added a drawing (limits.jpg) if this helps.





 


phonoplug

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Re: Problem Homing
« Reply #1 on: February 20, 2021, 11:15:14 PM »
Your "arm park position 1" is actually it's resting position when it's running. When you close the program it goes to 'park' the arm at the back left of the machine, a little forward (towards the user) of the single index slot points you have found for both x and y.

Try moving the arm over there then opening rvplace with a job. Hopefully that will resolve your start up homing problem.

sheaton

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Re: Problem Homing
« Reply #2 on: February 20, 2021, 11:58:25 PM »
So more like the attached image ?

Does it matter the angle of the forearm ?  Closer to the midline or away more from the midline ?  Or doesn't really matter.

I will give this a try tomorrow.  Thanks for your help.

Steve.


phonoplug

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Re: Problem Homing
« Reply #3 on: February 21, 2021, 12:06:39 AM »
The black part of the arm is correct but the grey part needs to be pointing to the left, maybe more 10 o'clock than 9 o'clock. I can take a photo of my machine on Monday if you need it still by then.

sheaton

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Re: Problem Homing
« Reply #4 on: February 21, 2021, 12:35:01 AM »
I am understanding like this :

Jason

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Re: Problem Homing
« Reply #5 on: February 21, 2021, 03:11:43 PM »
My Lower arm is about 275 degrees, upper arm is about 320 degrees when parked.

HTH,
  Jason

sheaton

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Re: Problem Homing
« Reply #6 on: February 21, 2021, 03:33:02 PM »
Thank you both.  I managed to home the machine this morning.  I can now let go of the Emergency Stop button.

Below are my findings for anyone who has not seen their machine working before purchase.

Steve.

alanambrose

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Re: Problem Homing
« Reply #7 on: February 22, 2021, 01:53:06 PM »
Thanks for properly documenting that Steve. Every bit increases the value of the archive to us RV-people :)

Alan

phonoplug

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Re: Problem Homing
« Reply #8 on: February 22, 2021, 05:25:40 PM »
This is what it looks like on my machine. Excuse the dust.... it does actually get used quite a lot!