rePally knowledge base

The rePally URCap is a repalletizer edition of the Pally URCap.

License

The rePally URCap requires its own license. The file name has the following format: no.rocketfarm.urcap.repalletizer.RobotSerialNo.license

Test licenses have the following name: no.rocketfarm.urcap.repalletizer.license

Installation

Both Pally and rePally can be installed on the same robot simultaneously. In this case two separate license files are required.

When installing Pally and rePally on the same robot, make sure the Daemon Port Number settings for the pallet manager daemon are different. The daemon processes will fail to start if the port numbers are identical.

It is technically possible to install different versions of Pally and rePally on the same robot, however, some unknown compatibility issues may occur.

Calibration

The calibration process is similar to Pally. However, there are some differences to be considered.

Sensor placement and logic

When using sensors on the conveyor, inverse logic might be required for the drop position. This means the program can proceed with dropping when there are no other boxes in that position. Make sure to select the 'inverse' checkbox next to the IO signals where needed.

Be careful when mounting the sensors on the conveyor. The drop signal sensor should be placed in a position where it can indicate there is enough room for dropping the box.

Calibration points

When calibrating the pick position: make sure that the gripper foam is slightly pressed against the box surface.

When calibrating the drop position: make sure that the boxes will not collide with the conveyor. Leave a small gap between the gripper foam and the box surface during calibration.

The rePally URCap has a built-in force-controlled motion when picking boxes from the pallet. The robot moves above the box pick point and then vertically down until a specific force is detected. It is therefore recommended to calibrate the pallet positions with respect to this extra motion, i.e. leave a small gap between the gripper foam and the box surface during calibration.

Convert Pally program to rePally program

Converting an existing Pally calibration to rePally is easy; just follow the steps below:

• create a new rePally program node

• move the robot to each Pally calibration point by pressing 'Move here', then 

• select the corresponding calibration point in rePally and press 'Set point' 

• make sure to leave a small gap between the gripper foam and the box surface for each calibration point as described earlier

• deactivate or remove the old Pally program node when finished.

Functional differences

The rePally URCap can depalletize from one pallet position to a specific drop position, and palletize from a specific pick position to the other pallet position. No other operation modes are currently supported.

The left and right pattern and pallet size can be different:

Open

Typical repalletizer setup 1

Depalletizing and palletizing actions are not directly synchronized with each other inside the main program, and the sequence is always controlled by the installed sensor logic:

• If the drop position is not occupied: depalletize to the drop position,

• If the pick position is occupied: palletize from the pick position,

• If both of the above are true at the same time, palletizing and depalletizing actions will be performed alternatingly.

This makes it possible to add any kind of extra machinery between the pick and drop positions:

Open

Typical repalletizer setup 2

The operator has to confirm when a new pallet is available on the left or right position. The program starts using the specified pallet only after operator confirmation.

The following table shows the main differences in the Pally-rePally terminology.

Callbacks

Callbacks are fully supported by rePally. When using a custom path, however, there is a slight difference to be considered.

In a palletizing step:

• onNextTask: called before the calculations of the next box start. Set MovePerformed=True to be able to use custom movement towards the pick position on the conveyor.

• beforeGrab: called when the robot is about to pick a box from the conveyor. Use custom motion to the pick position if needed.

• afterGrab: called when the robot is holding a box. Use custom motion to the pallet position if needed.

• afterRelease: called when the robot has dropped the box on the pallet. Use custom motion back to the waiting position if needed.

In a depalletizing step:

• onNextTask: called before the calculations of the next box start. Set MovePerformed=True to be able to use custom movement towards the pick position on the pallet.

• beforeGrab: called when the robot is about to pick a box from the pallet. Use custom motion to the pick position if needed.

• afterGrab: called when the robot is holding a box. Use custom motion to the drop position (conveyor) if needed.

• afterRelease: called when the robot has dropped the box on the conveyor. Use custom motion back to the waiting position if needed.

Other limitations

Currently there are no other known limitations.

Convert Pally program do rePally with script

Sample script to convert Pally.urp:

cat Pally.urp | gunzip | sed 's/installation=\"/installation=\"rePally./g' | sed 's/installationRelativePath=\"/installationRelativePath=\"rePally./g' | sed 's/\"Pally\"/\"rePally\"/g' | sed 's/\.palletmanager\.Palletizer/\.repalletizer\.Repalletizer/g' | sed 's/\.palletmanager\.UserCallback/\.repalletizer\.UserCallback/g' | gzip > rePally.urp

Sample script to convert default.installation:

cat default.installation | gunzip | sed 's/fileName=\"/fileName=\"rePally./g' | sed 's/\"Pally\"/\"rePally\"/g' | sed 's/palletmanager/repalletizer/g' | sed 's/PalletManager/Repalletizer/g' |  gzip > rePally.default.installation

Please note: replace the file names in the scripts to your own file names accordingly.