Bring the robot in safe position when starting a palletizing program

::heading=Context

When a palletizing program runs in operator mode, the operator cannot access UR move menu and cannot use UR freedrive, or robotiq active drive. 

Under this limitation the operator can have trouble restoring robot operation after an accidental stop (robot stuck in the pallet, robot colliding with something,... In most cases, the operator would need to move the robot up to get out of the problematic situation and move the robot away above the conveyor for example.

Adding a "homing" procedure in the before start section of the program can help to remove the robot from the problematic situation and give the possibility to the operator to restore operation without needing the assistance of the technician in charge of the machine. This article presents one way to achieve this.

::heading=Option 1: Move robot up at program start

Here under is a piece of program that can be added in the before start to move the robot up 100mm on program start.

The program tests if the robot has enough reach to move up to 200mm. We want the robot to have more than 100mm reach because after moving 100mm up the robot will start its trajectory to go to the pick position and will most likely initiate this trajectory with a vertical move. We need vertical reach to make this trajectory. Here we secure a 100mm extra vertical reach.

If the robot has a vertical reach of 200mm, we move the robot up of 100mm and the program starts from there.

::important=We can imagine that in the future we will implement something in our URCAP to avoid doing such a "homing" procedure. Be aware of the latest URCAP features before implementing this code.

::heading=Option 2: Add a home waypoint in the before start

If a home waypoint is added in the before start the operator will be prompted to move the robot at this position before starting the program. To move the robot the operator can directly go to this position or manually move the robot using the move menu (It is a bit strange because out of this situation, the operation cannot access the move menu...Anyway, that's helpful !).