Payload & Inertias

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.

I've written programs to dynamically change the payload via system variables, but never had a chance to test them.

Really it comes down to what Lemster said.

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.

Quote from Nation

I've written programs to dynamically change the payload via system variables, but never had a chance to test them.

Really it comes down to what Lemster said.

does that actually work?

I've always understood the system variables are just the last (or first) step, and other actions are needed to really make the controller use the new data.

Quote from rf103

does that actually work?

I've always understood the system variables are just the last (or first) step, and other actions are needed to really make the controller use the new data.

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:

: !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] ;

Calling the code:

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

Quote from JordanOlsen

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?

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.

Quote from JordanOlsen

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?

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.

Hello All,

I'am new in the blog and on robot.

It's possibile to change the robot payload from the PLC?

Quote from FelBire99

Hello All,

I'am new in the blog and on robot.

It's possibile to change the robot payload from the PLC?

hi,

Yes you need to declare in Comm Network PLC/ROBOT a Go/Gi and link in your program the value.

In the last exemple you need to link your Gi (Group Input robot, OutPut PLC a Word or a Byte as you wish) with the AR[1] = Weight of payload (kg)

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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How did you get the *980 into the program? What is the 980 doing? I ran this code and it did work, but I didn't think it did because I didn't have the 980 in there. My values were so small that I couldn't even see them in the motion parameter because there was two decimals places in front of the values.