Payload & Inertias

Hey guys,

I am new to Fanuc. We are implementing robot operated cells into our production. I am currently working on programming a Fanuc r2000ib 165f to run a Haas ST30 and a Mitsubishi GD30 Gear hobber. In this application, our R2000ib will experience 7 different payloads throughout one cycle:

Base load for our grippers and mounting plates;

base load with 1 raw part;

base load with a half turned part;

baseload with full turned part and blank part;

base load with full turned part only;

Base load with hobbed part only;

and base load with fully turned part and hobbed part.

We are looking for variability in this area and a way to quickly change the payload values whenever we switch jobs. Every new job will have different weights, lengths and ODs. This changes all the payload values. Doing the Payload Ident takes far too long for production to change to the next job. All the videos I have watched only talk about setting payloads for the tooling they are using. I have not been able to find and videos for payload setting for machine tending or pick and place. Any help would be greatly appreciated. Thanks guys! We do not have access to roboguide either.

Quote from Lemster68

How much do these gears weigh? If you are talking a couple kilograms the percentage of the robot's handling capacity will be so small that the robot would hardly notice. Now if you are talking tens, twenty or more, then sure.

Depending on the job, material, OD, length these parts can weigh between 10-40 kilos. and there is instances where the robot will have a part in both grippers at the same time.

Quote from Nation

I've ran into that as well, especially in force control applications. So I decided to test it in roboguide.

Trial 1 (Payload set to 1kg programmatically on a R2000iC/210F running V8.30 HandlingPro):

Trial 2 (Payload set to 150kg programmatically on a R2000iC/210F running V8.30 HandlingPro):

Appears to work.

The Code:

Code

: !Program Description: Rewrites ;
: !payload id 1, and sets it. ;
: !Takes the following arguments: ;
: ! AR[1] = Weight of payload (kg) ;
: ! AR[2-4] = CoG (cm). ;
: ! AR[5-7] = Inertias (kgfcm^2). ;
: ;
: !Payload in kg. ;
: $PLST_GRP1[1].$PAYLOAD=(AR[1]) ;
: !Payload CoG in cm. ;
: $PLST_GRP1[1].$PAYLOAD_X=(AR[2]) ;
: $PLST_GRP1[1].$PAYLOAD_Y=(AR[3]) ;
: $PLST_GRP1[1].$PAYLOAD_Z=(AR[4]) ;
: !Payload inertia in kgfcm^2. ;
: $PLST_GRP1[1].$PAYLOAD_IX=(AR[5]*980) ;
: $PLST_GRP1[1].$PAYLOAD_IY=(AR[6]*980) ;
: $PLST_GRP1[1].$PAYLOAD_IZ=(AR[7]*980) ;
: PAYLOAD[1] ;

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Calling the code:

Code

38:  CALL SET_PAYLOAD(35,0,5,20,0,0,20) 

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I'm apologize for asking but we do not have Roboguide, is there any way you could possibly explain a little more in depth what your pictures are showing. Also would we need HandlingPro software to be able to run a program like this?

Quote from byrol

I did a similar study with an "R-2000" robot. However, even if you set the "upload/ident" settings as much as you want in the robot software, the robot does not make an accurate measurement of any of the loads below 5 kg. In addition, measuring a kilogram of this load to a robot leads to a serious waste of time, and over time, servo drives begin to make meaningless movements. Then we connected an analog weight reading sensor to the head that we wanted the robot to hold and weigh its weight, and this sensor to the PLC and received a DO output from the PLC with the desired weight values in the internal software and made a signal input to the robot. Indeed, when we do this with PLC and sensor "loadcell", it is not slow as I feared, but on the contrary, it works very fast. That's how I found a solution.

Using this method will input the new data for mass, COG, and the inertias into our selected payloads? such as payload 1 or payload 2 and so on...

Quote from Nation

You don't need roboguide to run this. The code posted is regular TP code that can run on the pendant.

I ran it in roboguide because I have never tested it before. In roboguide you can generated TCP traces and color them by various means. In the pictures, I colored them by acceleration, as when a robot has a higher payload, it will accelerate slower. It was a means to verify the untested code was having an effect.

Thank you this helps I will be trying this in a few minutes. I do have a question regarding the inertias though. I noticed you entered 0 for both your inertia in x and y. Was this only for the sake of your example or are the inertias not as important? Also do you know of an equation to get the unit kgfcm^2 I have never seen kgf as a unit before so not too sure where to start with that. and in your call program, You are able to simply enter in the values just by placing them in parenthesis separated by a comma?

Quote from Nation

That was just for the example. Ideally you want to have as an accurate payload as possible.

Kgf is kilogram force. I have no idea why Fanuc decided on that weird unit. 1 Kg m² is equal to 10.20408163 Kgf cm s², or 1 Kgf cm s² is equal to 0.098 Kg m².

Hey man thanks a lot for all the info! seriously helped me out a bunch. Appreciate it