Move Waypoint In One Direction Based On User Input?

zrehlander 2020-06-16

I have a UR10 that we want to use to tend a CNC lathe. I am wanting to teach the pallet sequence at the lowest spot on the table for a general program. For future uses I would like for the operator to be able to type in the Z dimension of the part that is being picked up and have the robot automatically offset that Z distance from the Lowest spot on the table that has already been taught. The X, Y, and rotations should remain the same. This way we would not have to reteach the pallet sequence for every job, rather we would just change the user input of part height and the program would do the rest for us.

I currently only use the polyscope tablet for programming our robot as I have not messed with any of the script programming to date.

What would be the best way to accomplish this?

zrehlander 2020-06-16

For Example:

I have my "Reference" position as p[-0.24712, -0.21240, -0.35914, 2.0482, 2.3821, 0.0057]. For example if I have a 50mm part I am trying to change this waypoint to p[-0.24712, -0.21240, -0.30914, 2.0482, 2.3821, 0.0057] to lift the grippers up off the table a bit.

I have tried making variables for Part Height, and placing that into the spot for Z in the new position but it does not seem to be working. When I look in my variables screen it shows the right pose numbers, but the arm is traveling way further down that what I am wanting.

jelms 2020-06-16

@zrehlander I defined a variable on the installation tab and this worked in the simulator. This should move to the waypoint and then z_offset away from it. Hope that helps.

 Program
   Robot Program
     Folder
       MoveJ
         Waypoint_1
       Wait: 2.0
     Folder
       w2≔pose_add(Waypoint_1, p[0,0,z_offset,0,0,0])
       MoveJ
         w2
       Wait: 1.0

zrehlander 2020-06-16

Thank you. That seems to work with the height offset. Do you know how I can get the nested inside of the pallet command? I have tried doing this for the Corner 1-4 but they are not able to be altered other than teaching the point. When I did it for the Approach and Pick points it seemed to work, but it would just keep returning to the first square and not index to the next position in the position.

jelms 2020-06-17

Yeah I don't think there is quite a way to do that. The best I can think of is defining the pallet at the highest z you would need to support and using an additional variable waypoint down before doing the operation. But this will move to the position on the originally defined pallet first so not the most efficient.

Using the simulator and saving this also generates a script that you could then modify. The code below generates a script that is attached.

Program
   Robot Program
     Pallet
       Pattern: Square
         Corner1_1
         Corner2_1
         Corner3_1
         Corner4_1
       PalletSequence
         anchor
         Wait: 1.0
         var_2≔pose_add(get_actual_tcp_pose(), p[0,0,z_offset,0,0,0])
         var_2
         Wait: 3.0
         'Do you gripper or whatever here'
         Exit

matthewd92 2020-06-17

Here is how we solve for palletizing, we do not use the built-in wizard as we generally want more control than that allows (file is attached, you can remove the .txt off the end and then use on the robot.

Setup the pallet with 4 columns and 4 rows spaced evenly 100mm apart in both X and Y

pallet_setup(x_offset = 0.1, y_offset =0.1, numInX = 4, numInY = 4)

Create a feature plane called `pallet_corner` the X axis should align with your rows, Y axis with the columns, Z aligned with the tool (generally pointing into the table)

These functions are based on 0 based indexing, so the first position you would go to would be position 0, in our example the last position would be 15 (4*4-1)

local nextPosition = pallet_nextPosition(someSpace) #This would always stay on the plane

local nextPosition = pallet_nextPositionAtHeight(space, z_offset) #This would allow you to define a new 
z_offset from the plane that was taught

If the robot does not move in the correct Z_position, simply flip the sign on what you are passing in. We assume that the positive number should come off the plane and so we reverse the sign in function

You would simply then use that nextPosition in your move using a variable as the waypoint type. You could also calculate your over pick position like this

local overPickPosition = pose_trans(nextPosition, p[0,0,-0.05,0,0,0] # This would be 50mm above the part (assuming Z points into the table, otherwise flip the sign on Z)