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Unknown WO weight

laov
laov ✭
in RAPID Programming
Hello,

My robot is trying to pick up WO of unknown weight. The weight can varry from small to close to carrying limit.

Is it possible to measure WO weight during a pick and define it as gripped load?


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Best Answer

  • graemepaulin
    graemepaulin mod
    Answer ✓
    You might be able to use the motor torque on say axis 3 ( using the Rapid command GetMotorTorque) to deduce the mass of the payload.
    You would have to pick up a range of sizes of the product collecting the motor torque and manual measuring the mass - if it is a linear correlation then you can use the torque reading to get the mass.
    This mass can then be written into the loaddata for example, load1.mass:= CalculatedMass;

Answers

  • lemster68
    lemster68 ✭✭✭
    You will need to define unique loaddatas for each object picked and run the LoadID service routine for each.
    Lee Justice
  • laov
    laov ✭
    lemster68 said:
    You will need to define unique loaddatas for each object picked and run the LoadID service routine for each.
    That is not an option. As I said the load is an unknown and varriable.
  • laov
    laov ✭
    graemepaulin said:
    You might be able to use the motor torque on say axis 3 ( using the Rapid command GetMotorTorque) to deduce the mass of the payload.
    You would have to pick up a range of sizes of the product collecting the motor torque and manual measuring the mass - if it is a linear correlation then you can use the torque reading to get the mass.
    This mass can then be written into the loaddata for example, load1.mass:= CalculatedMass;
    Thank you for the direction. I will hopefully get the chance to try it and post the ressults.
  • laov
    laov ✭
    laov said:
    graemepaulin said:
    You might be able to use the motor torque on say axis 3 ( using the Rapid command GetMotorTorque) to deduce the mass of the payload.
    You would have to pick up a range of sizes of the product collecting the motor torque and manual measuring the mass - if it is a linear correlation then you can use the torque reading to get the mass.
    This mass can then be written into the loaddata for example, load1.mass:= CalculatedMass;
    Thank you for the direction. I will hopefully get the chance to try it and post the ressults.
    This is possible but to have any semblance of reliability you will need to have a constant target at which you will measure your torque as torque measurements for the same axes at different targets using the same mass can be vastly different. This is also in no way precise but good enough to tell apart 10, 100, 200 kg mass.

    However for my use case it was not possible to fully implrement this as a constant target only apears close to the destination and at that point this measurement seems to be pointless for a movement of less than 1m and no demand for precision at the target (+-1 cm is good enough).
  • Newman
    Newman ✭
    I've used the motor torque from axis 3 to place fiberboards in stacks with unknown height. But as mentioned before, the torque varies a lot depending on where the stack is located and in my case if the pallet was close to full or close to empty.

    I logged torque values and position with "Errwrite\I" and then made a function to set threshhold depending on current height.
    -----------------
    David
    Swedish freelance ABB robot programmer

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